Thermal image transfer recording medium
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a thermal image transfer recording medium capable of producing highly reliable transferred images having improved friction and scratch resistance and heat resistance, and chemical resistance. 
     2. Discussion of Background 
     There are conventionally known thermal image transfer recording media having an ink layer comprising an epoxy resin with a softening point of 60 to 110° C. and a coloring agent, as disclosed in Japanese Laid-Open Patent Application 60-59159. Such conventional thermal image transfer recording media can yield transferred images on a sheet of plain paper, a plastic film and a sheet of metallic foil in one coloring operation, and further, the thus transferred images have good preservability and wear-resisting properties. 
     However, since the ink layer of the above-mentioned conventional thermal image transfer recording medium comprises the epoxy resin having a softening point of 60 to 110° C., as previously mentioned, the thermal image transfer recording medium is poor in the friction-resisting properties at high temperatures. More specifically, the transferred images become blurred and illegible when rubbed with corrugated cardboard at high temperatures, for instance, at 70° C. 
     Further, images transferred on a recording sheet from the above-mentioned conventional recording medium containing epoxy resin do not have so much sufficient lubricating properties that they readily lift off the recording sheet when brought into contact with hard materials such as metal edge or a nail. 
     In addition, the conventional thermal image transfer recording medium has the shortcoming that the transferred images obtained are vulnerable to chemicals, for example, industrial alcohol, engine oil, brake oil, kerosene, car wax, toluene, xylene, and &#34;Perclene&#34; for dry-cleaning. 
     SUMMARY OF THE INVENTION 
     It is therefore a first object of the present invention to provide a thermal image transfer recording medium capable of producing highly reliable transferred images having excellent friction and scratch resistance and chemical resistance. 
     A second object of the present invention is to provide a thermal image transfer recording medium in which an ink layer does not readily lift off a substrate at low temperatures. 
     A third object of the present invention is to provide a thermal image transfer recording medium having an improved thermosensitivity. 
     The above-mentioned objects can be attained by a thermal image transfer recording medium comprising a substrate and an ink layer formed thereon, which ink layer comprises as the main components (i) a coloring agent and (ii) a copolymer consisting of at least one monomer selected from Group A consisting of acrylonitrile and methacrylonitrile and at least one monomer selected from Group B consisting of the monomers represented by formula (I); ##STR2## wherein R 1  represents hydrogen or a methyl group; and R 2  represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a glycidyl group, or a hydroxyalkyl group having 2 to 4 carbon atoms. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     According to the present invention, the following types of the thermal image transfer recording media can be provided: 
     (1) A thermal image transfer recording medium which is so constructed that an ink layer comprises as the main components (i) a coloring agent and (ii) a copolymer consisting of at least a monomer selected from the following group A and at least a monomer selected from the following group B. 
     Group A: acrylonitrile and methacrylonitrile. 
     Group B: a monomer represented by the following formula (I); ##STR3## wherein R 1  represents hydrogen or a methyl group; and R 2  represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a glycidyl group, or a hydroxyalkyl group having 2 to 4 carbon atoms. 
     (2) A thermal image transfer recording medium which is so constructed that a lubricating properties-imparting agent layer and the above-mentioned ink layer are successively overlaid in that order on a substrate. (3) A thermal image transfer recording medium which is so constructed that an adhesion-promoting agent layer is formed on the above-mentioned substrate, and then the ink layer as in the above-mentioned type (1), or the lubricating property imparting layer and the ink layer as in the above-mentioned type (2) are formed thereon. 
     (4) A thermal image transfer recording medium which is so constructed that a thermosensitivity-promoting agent layer comprising as the main components a thermofusible material and/or a heat-softening material is formed on the above-mentioned ink layer employed in the types (1), (2) and (3). 
     Examples of the substrate for use in the present invention are conventionally known plastic film and paper. For example, a plastic film having relatively high heat-resistance, such as polyester film, polycarbonate film, triacetyl cellulose film, nylon film and polyimide film; and a sheet of paper such as cellophane and perchment paper are appropriate. 
     It is preferable that the thickness of the substrate for use in the present invention be in the range of 2 to 15 μm, in the case where images are transferred from the thermal image transfer recording medium to a recording sheet, with the application of thermal energy to the recording medium by a thermal head. In such a case, a heat-resistant protective layer may be provided on the back side of the substrate, opposite to the ink layer, to improve the heat-resistant properties thereof. 
     Examples of the materials for the heat-resistant protective layer for use in the present invention are silicone resin, fluoroplastic, polyimide resin, epoxy resin, phenolic resin, melamine resin and nitrocellulose. 
     When a heat source, which can selectively heat a spot of the ink layer, such as a laser beam, is employed, there will be no limitation to the thickness of the substrate. 
     The coloring agent contained in the ink layer for use in the present invention can be appropriately selected from carbon black, organic pigments, inorganic pigments and dyes in compliance with the requests for the color tone of images. 
     The ink layer of the thermal image transfer recording medium according to the present invention comprises a copolymer of acrylonitrile and/or methacrylonitrile, and at least one comonomer of the previously mentioned formula (I). 
     Examples of the comonomer used in forming a copolymer together with the acrylonitrile or methacrylonitrile are methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, glycidyl methacrylate, glycidyl acrylate, 2-hydroxyethyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate and 2-hydroxypropyl methacrylate. 
     Examples of the thus formed copolymers are acrylonitrile-methyl methacrylate, acrylonitrile-methyl acrylate, acrylonitrile-ethyl methacrylate, acrylonitrile -ethyl acrylate, acrylonitrile-n-butyl methacrylate, acrylonitrile-glycidyl methacrylate, acrylonitrile-glycidyl acrylate, acrylonitrile-2-hydroxyethyl methacrylate, acrylonitrile-isobutyl methacrylate, acrylonitrile-tert-butyl methacrylate, acrylonitrile-2-hydroxypropyl methacrylate, methacrylonitrile-methyl methacrylate, methacrylonitrile-methyl acrylate, methacrylonitrile-ethyl methacrylate, methacrylonitrile-ethyl acrylate, methacrylonitrile-n-butyl methacrylate, methacrylonitrile-glycidyl methacrylate, methacrylonitrile -glycidyl acrylate, methacrylonitrile-2-hydroxyethyl methacrylate, methacrylonitrile-isobutyl methacrylate, methacrylonitrile-tert-butyl methacrylate, and methacrylonitrile-2-hydroxypropyl methacrylate. 
     Among the above copolymers, acrylonitrile-glycidyl methacrylate, acrylonitrile-methyl methacrylate and acrylonitrile-ethyl methacrylate are particularly superior to others, because their heat-, chemical- and friction-resistant properties are excellent, and further they can be easily manufactured. 
     Besides the above bipolymers, terpolymers can be employed by selecting a monomer from the groups A, B and C, respectively: 
     Group A: acrylonitrile and methacrylonitrile. 
     Group B: (meth)acrylic acid ester monomers represented by the following formula (II); ##STR4## R 1  represents hydrogen or a methyl group; and R 2  represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, or a hydroxyalkyl group having 2 to 4 carbon atoms. 
     Group C: glycidyl acrylate and glycidyl methacrylate. 
     Each comonomer of Group A, B or C has the following functions: 
     Group A: imparting the chemical-resistant and heat-resistant properties to the ink layer, and increasing the mechanical strength of the ink layer. 
     Group B: imparting thermal plasticity and chemical-resistant properties to the ink layer, and controlling the glass transition temperature (Tg) of the ink layer. 
     Group C: increasing the adhesion property of the ink layer to the substrate, promoting the crosslinking performance and imparting the heat-resistant property to the ink layer. 
     When the above-mentioned terpolymer is employed in the ink layer of the thermal image transfer recording medium according to the present invention, it is preferable that the composition ratio of the comonomers in the terpolymer be in the following range: ##EQU1## 
     When the terpolymer whose comonomer composition ratio is within the above range is employed in the ink layer, the thermal image transfer recording medium according to the present invention can exhibits sufficient mechanical strength and high chemical-resistant properties. In addition, the ink layer of the recording medium has the advantage in that it has no curling problem. 
     Depending on the molecular weight of the copolymer employed in the ink layer, the melt viscosity thereof varies, which affects the thermosensitivity of the thermal image transfer recording medium in the course of thermal printing. From the viewpoint of the thermosensitivity of the thermal image transfer recording medium, it is preferable that the weight-average molecular weight (Mw) of the copolymer on a basis of acrylonitrile or methacrylonitrile for use in the present invention be in the range of 2,000 to 1,000,000, more preferably in the range of 3,000 to 500,000. With respect to the number-average molecular weight (Mn), it is preferable that the above-mentioned copolymer employed have a number-average molecular weight ranging from 1,000 to 500,000, and more preferably ranging from 1,500 to 250,000. The above-mentioned weight-average molecular weight (Mw) and number-average molecular weight (Mn) are represented in terms of the respective values converted to polystyrene by gel permeation chromatography (GPC). 
     The foregoing copolymers can be easily obtained by the conventional methods. For example, the above-mentioned monomers are polymerized in a solvent at an appropriate temperature in the presence of a radical polymerization initiator such as benzoyl peroxide and azobisisobutyronitrile. For obtaining the copolymers, the conventional emulsion polymerization method can be employed. 
     When a copolymer having curable functional groups prepared by use of glycidyl methacrylate is employed, an appropriate thermosetting agent may be added to the composition of the ink layer. 
     Representative examples of the above-mentioned thermosetting agents are phenolics, such as phenolic resin; primary amine; secondary amine; complex compounds of amine, such as complex compounds of amine and Lewis acids, in particular, borontrifluoride, just like in the form of BF 3  ·C 2  H 5  ·NH 2  ; organic acids and organic acid anhydrides. 
     Stoichiometrically, the thermosetting agent may be added to the composition of the ink layer in an amount chemically equivalent to the amount of the glycidyl groups contained in the copolymer employed in the ink layer. 
     Furthermore, the friction and scratch resistance, heat resistance and chemical resistance of the thermal image transfer recording medium can be improved by use of a copolymer in the ink layer, which is prepared from (a) a monomer from the Group A, (b) a monomer from the Group B and (c) a monomer from the Group C, with at least part of the glycidy groups thereof being modified by alkanolamine. It is more preferable that the above-mentioned copolymer be used together with a blocked isocyanate in the ink layer. 
     An example of the above copolymer is represented by the following formula (III): ##STR5## wherein R 1 , R 2 , R 3  and R 4  each represent hydrogen or CH 3  ; R 5  represents hydrogen or a straight-chain or branched alkyl group having 1 to 4 carbon atoms, which is substituted by a hydroxyl group; and R 6  represents a straight-chain or branched alkyl group having 1 to 4 carbon atoms, which is substituted by a hydroxyl group. 
     When the above-mentioned copolymer of the formula (III) is employed in the ink layer of the thermal image transfer recording medium according to the present invention, it is preferable that the composition ratio by weight of (l):(m):(n):(x) be in the range (20 to 80%):(10 to 50%):(1 to 40%):(0 to 50%), and more preferably in the range of (40 to 60%):(20 to 40%):(10 to 30%):(0 to 30%). 
     When the copolymer whose comonomer composition ratio is within the above range is employed in the ink layer, the obtained thermal image transfer recording medium according to the present invention exhibits sufficient mechanical strength and high chemical-resistant properties. In addition, the ink layer of the recording medium is sufficiently flexible. 
     Depending on the molecular weight of the copolymer of formula (III) employed in the ink layer, the melt viscosity thereof varies, which affects the thermosensitivity of the thermal image transfer recording medium in the course of thermal printing. From the viewpoint of the thermosensitivity of the thermal image transfer recording medium, it is preferable that the copolymer of formula (III) have a weight-average molecular weight(Mw) ranging from 3,000 to 20,000 and a number-average molecular weight (Mw) ranging from 1,500 to 100,000, which are each represented in terms of the values converted to polystyrene by gel permeation chromatography (GPC). 
     The above-mentioned copolymer of formula (III) can be obtained by a conventional method including two steps. 
     At the first step, polymerization is carried out in a solvent at an appropriate temperature in the presence of a polymerization initiator such as benzoyl peroxide and azobisisobutyronitrile. 
     At the second step, at least part of glycidyl methacrylate is modified by alkanolamine. After the removal of unreacted monomers, ring opening reaction is initiated in such a manner that the glycidyl groups contained in the copolymer are allowed to react with alkanolamine in such a range that the amount of the alkanolamine is equimolar to that of the glycidyl groups in the copolymer. 
     Examples of the alkanolamine for use in the present invention are monoethanolamine and diethanolamine. From the viewpoint of reactivity, diethanolamine is preferable for use in the present invention. 
     By controlling the amount of the alkanolamine to be reacted for modification at the second step of the preparation of the copolymer, glycidyl methacrylate units can be partially remained as they are in the modified copolymer, so that the advantages of the glycidyl group can also be efficiently utilized in the recording layer. More specifically, when both of the glycidyl groups and the alkanolamine-modified groups exist in the copolymer at the same time, the advantages of the glycidyl groups, such as improved adhesion strength of the ink composition to a transferred sheet, high glass transition temperature (Tg) and excellent crosslinking properties, can coexist with the advantages of the alkanolamine-modified group, such as good flexibility of the ink layer and excellent reactivity with isocyanate. 
     When the above-mentioned copolymer is employed, the previously mentioned thermosetting agent may be contained in the ink layer. 
     The glycidyl group modified by alkanolamine exhibits excellent reactivity with isocyanate, because the characteristics of amine are imparted thereto by the modification so that the crosslinking thermosetting reaction can proceed smoothly. 
     The above-mentioned blocked isocyanate, serving as a crosslinking agent in this reaction, will now be explained in detail. 
     The blocked isocyanate, whose isocyanate group is protected therein, does not set during storage, and accordingly the thermosensitivity thereof does not deteriorate. 
     Examples of isocyanate for use in the present invention are tolylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, a dimer and a trimer of tolylene diisocyanate, hexamethylene diisocyanate, and an adduct of 2,4-tolylene diisocyanate with trimethylolpropane. As a blocking agent used for the blocked isocyanate, phenol, acetylacetone, caprolactone and oxime can be employed. Among them, oxime-type blocking agents are preferable from the viewpoint of the dissociation temperature and the stability at room temperature. 
     It is preferable that the above blocked isocyanate be contained in the ink layer composition in an equimolar amount to or in an amount of about 10% more than that of the hydroxyl groups in glycidyl-methacrylate-modified alcohol. 
     The crosslinking reaction of the above-mentioned isocyanate and the glycidyl group itself also proceeds with the formation of oxazolidone rings. This reaction is described in detail in M. E. Dyen; D. Swern: Chem. Rev. 67, 197(1967). 
     The present invention will now be explained in detail by referring to the lubricating properties-imparting agent. 
     The lubricating properties-imparting agent improves the lubricating properties of the surface of images thermally transferred on the recording sheet. The more improved the lubricating properties of the surface of the images, the lower the friction coefficient thereof when the images are brought into contact with the objects such as metal, corrugated board and wood. The lubricating properties-imparting agent has a function of preventing the stress from being concentrated at a spot of the transferred images. 
     Examples of the lubricating properties-imparting agents for use in the present invention are lubricants such as wax-type fatty amide and phosphate ester; waxes such as natural paraffin wax, candelilla wax and carnauba wax; oils such as silicone oil and perfluoroalkyl ether; resins such as silicone resin, fluoroalkyl ether resin; and lubricity-providing particles such as polytetrafluoroethylene (PTFE), SiO and SiO 2 . Among the above, carnauba wax is the most effective because it gives both mechanical strength and lubricating properties well-balancedly to the ink composition. 
     It is preferable that the amount of the lubricating properties-imparting agent be in the range of 1 to 30 wt. % of the amount of the aforementioned copolymer. 
     As a matter of course, the above lubricating properties-imparting agent may be added to the composition of the ink layer. The agent can further exert its effect when a lubricating properties-imparting agent layer comprising the above lubricating properties-imparting agent is independently interposed between the substrate and the ink layer. In this case, paraffin wax and carnauba wax are the most preferable. If carnauba wax is employed in the lubricating properties-imparting agent layer, the lubricating properties-imparting agent layer may be as thick as 0.3 to 2.0 μm. 
     Furthermore, additive components such as a flexibility-providing agent, a thermosensitivity-controlling agent and wear-resistance improving agent can be added to the composition for the ink layer. For example, the flexibility-providing agent such as dioctylphthalate (DOP); the thermosensitivity-controlling agent such as ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA) or synthetic rubber; and the wear-resistance improving agent such as thermoplastic resins of acrylic resin and polyester resin can be contained in the ink layer composition. 
     The thickness of the ink layer may be appropriately adjusted depending on the surface smoothness of the recording sheet employed. When a polyester film, which has a remarkably smooth surface, is used as the recording sheet, the 1.0 to 2.5-μm-thick ink layer is thick enough to produce the images invulnerable to friction and scratch, with sufficient thermosensitivity being maintained. When coated paper or high-quality paper is employed, the thickness of the ink layer may be set in the range of about 2.5 to 4.0 μm from the viewpoint of the image quality. Furthermore, in the case where a thermosensitivity-promoting agent layer, to be described later, is formed on the ink layer, it is preferable that the thickness of the ink layer be in the range of about 1.5 to 3.0 μm. 
     The present invention will be now explained in detail by referring to an adhesion-promoting agent layer. 
     In order to prevent the ink layer from falling off the substrate in the course of operation at low temperatures, for example, at 0° C., the above-mentioned adhesion-promoting agent layer can be provided. More specifically, in the case where the thermal image transfer recording medium type (1) according to the present invention is employed, the adhesion-promoting agent layer can be interposed between the substrate and the ink layer. When the thermal image transfer recording medium type (2) is employed, the adhesion-promoting agent layer can be interposed between the substrate and the lubrication properties-imparting agent layer. In any case, the adhesion-promoting agent layer may be transferred to the recording sheet together with the ink layer, or left on the substrate after thermal image transfer. 
     The materials which have a tendency to show flexibility at room temperatures are suitable for the adhesion-promoting agent. Examples of the adhesion-promoting agents for use in the present invention are resins such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl chloride copolymer, polyvinyl butyral, natural rubber, and synthetic rubber. 
     When the adhesion-promoting agent layer is designed to be transferred to the recording sheet, it is recommendable that some waxes having an appropriate melting point, such as paraffin wax and carnauba wax may be mixed together with the above-mentioned adhesion-promoting agent, in an amount ratio of 30 to 70 wt. %. It is preferable that the thickness of the adhesion-promoting agent layer be in the range of 0.2 to 1.0 μm. 
     The present invention will now be explained in detail by referring to a thermosensitivity-promoting agent layer. 
     The above-mentioned thermal image transfer recording media according to the present invention are capable of producing transferred images having improved friction and scratch-resistance and heat-resistance. To obtain further clear images, for instance, fine lines free from partial omission and dense solids, increased thermal energy is required to apply to the thermal image transfer recording medium. If thermal-printing is performed by using a commercially available printer under application of a platen pressure of 150 g/cm 2  at a printing speed of 10 cm/sec, clear images can be obtained on a highly smooth recording sheet such as a film sheet when a thermal energy of 20 mJ/mm 2  is delivered to the recording medium. In contrast, clear images cannot be obtained on a less smooth recording sheet such as mirror-coat paper until an energy attains no less than 25 mJ/mm 2 . 
     With the above taken into consideration, the thermosensitivity-promoting agent layer can be provided on the ink layer. By the aid of the thermosensitivity-promoting agent layer, the thermosensitivity of the ink layer is improved, with the friction and scratch-resistance and heat-resistance substantially maintained. 
     The thermosensitivity-promoting agent layer for use in the present invention comprises as the main components a thermofusible material and/or a heat-softening material. 
     The preferable thermofusible material has a melting point of 60 to 130° C., and shows a melt viscosity of 1000 cps or less at 140° C. Specific examples of the above thermofusible materials for use in the present invention are waxes such as paraffin wax, carnauba wax, candelilla wax and polyethylene wax; and fatty amide. The heat-softening materials which have high adhesion properties to a recording sheet are preferable, and examples of the heat-softening materials for use in the present invention are ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, acrylic resin, and polyester resin, in particular branched polyester resin. 
     The thermosensitive-promoting agent layer can exert its effect sufficiently when the above-listed heat-softening material is employed alone, but to meet the further requirements for the improvement in the surface properties of the recording medium, the increase in printing speed, and the improvement of image quality even on a recording sheet having a low surface-smoothness, the above-mentioned thermofusible materials may be mixed with the heat-softening material. 
     On the other hand, when the thermofusible material is employed alone in the thermosensitivity-promoting agent layer, it can function as a thermosensitivity-promoting agent in the case where the employed recording sheet has relatively low surface smoothness. However, as the surface smoothness of the employed recording sheet is getting higher, the obtained images become poor in the friction and scratch resistance. For example, the transferred images become vulnerable to the friction and scratch by a stainless steel edge and a pencil with a hardness of 2H, to be described later. In such a case, therefore, the thermofusible material and the heat-softening material may be used in combination. 
     The melt viscosity of the thermosensitivity-promoting agent, which determines the thermosensitivity of the recording medium, are preferably in the range of 50 to 5000 cps at 140° C., when measured by a B-type rotational viscometer. It is preferable that the mixing ratio of the thermofusible material and heat-softening material be in the range of (95 to 5) to (0 to 100). 
     When the employed recording sheet has relatively high surface smoothness, the thermosensitivity-promoting agent layer is preferably as thin as possible, as far as the thermosensitivity-promoting agent layer can bear the adhesion to the ink layer and the mechanical strength thereof is not deteriorated. In contrast to this, when images are transferred on the recording sheet with low surface smoothness, it is recommended that the thermosensitivity-promoting agent layer be designed as thick as possible, as far as the thermosensitivity thereof is not deteriorated, so that satisfactory thermal image transfer performance of the ink layer can be maintained in spite of unsmoothness of the recording sheet. From the above viewpoints, it is preferable that the thickness of the thermosensitivity-promoting agent layer for use in the present invention be in the range of 0.1 to 1.5 μm, more preferably in the range of 0.3 to 1.0 μm. 
     Other features of this invention will become apparent in the course of the following description of exemplary embodiments, which are given for illustration of the invention and are not intended to be limiting thereof. 
    
    
     EXAMPLE 1 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600]                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 1 according to the present invention was obtained. 
     EXAMPLE 2 
     The procedure for Example 1 was repeated except that methyl methacrylate-acrylonitrile copolymer employed in the ink layer coating liquid in Example 1 was replaced by the following copolymer, whereby a thermal image transfer recording medium No. 2 according to the present invention was obtained. 
     Copolymer: Methyl methacrylate-acrylonitrile (weight ratio=50:50) [Mw=7700, Mn=4100] 
     EXAMPLE 3 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               76                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600]                                      
Lubricating properties-                                                   
              Silicone oil      4                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 3 according to the present invention was obtained. 
     EXAMPLE 4 
     Formation of Lubricating Properties-imparting Agent Layer 
     A mixture of carnauba wax and paraffin wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
           Carbon black     20                                            
Copolymer: Methyl methacrylate -                                          
                            70                                            
           acrylonitrile copolymer                                        
           (weight ratio = 70:30)                                         
           [Mw = 6400, Mn = 3600]                                         
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 4 according to the present invention was obtained. 
     EXAMPLE 5 
     Formation of Adhesion-promoting Agent Layer 
     A mixture of ethylene-vinyl acetate copolymer having a melt index of 150 (40% of vinyl acetate) and carnauba wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare an adhesion-promoting agent layer coating liquid. 
     The thus prepared adhesion-promoting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 0.5 μm on a dry basis, and dried, so that an adhesion-promoting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing a solid portion of 20%: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600]                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared adhesion-promoting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 5 according to the present invention was obtained. 
     Even when the thus obtained thermal image transfer recording medium No. 5 was crumpled, the ink composition hardly fell off the recording medium and the adhesion promoting effect was confirmed. 
     EXAMPLE 6 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               57                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600]                                      
Additive agents:                                                          
Flexibility-providing                                                     
              Styrene butadiene rubber                                    
                                3                                         
agent:                                                                    
Thermosensitivity-                                                        
              Linear polyester resin                                      
                               10                                         
controlling agent:                                                        
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 6 according to the present invention was obtained. 
     EXAMPLE 7 
     The procedure for Example 1 was repeated except that methyl methacrylate-acrylonitrile copolymer employed in the ink layer coating liquid in Example 1 was replaced by the following copolymer, whereby a thermal image transfer recording medium No. 7 according to the present invention was obtained. 
     Copolymer: Glycidyl methacrylate-acrylonitrile (weight ratio=50:50) [Mw=8000, Mn=3900] 
     EXAMPLE 8 
     The procedure for Example 1 was repeated except that methyl methacrylate-acrylonitrile copolymer in the ink layer coating liquid employed in Example 1 was replaced by the following copolymer, whereby a thermal image transfer recording medium No. 8 according to the present invention was obtained. 
     Copolymer: Glycidyl methacrylate-methacrylonitrile (weight ratio=60:40) [Mw=10000, Mn=4900] 
     COMPARATIVE EXAMPLE 1 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in toluene to prepare an ink layer coating liquid containing 15% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
           Carbon black     20                                            
Binders:   Paraffin wax     40                                            
           (melting point of 68° C.)                               
           Carnauba wax     20                                            
           (melting point of 81° C.)                               
           Ethylene - vinyl acetate                                       
                            10                                            
           copolymer (28% of vinyl                                        
           acetate)                                                       
           [melt index = 250]                                             
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a comparative thermal image transfer recording medium No. 1 was obtained. 
     COMPARATIVE EXAMPLE 2 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
          Carbon black       20                                           
Binders:  Bisphenol A type-  80                                           
          epoxy resin (Trademark                                          
          &#34;Epicote 1002&#34; made by                                          
          Yuka Shell Epoxy K.K.)                                          
          softening point of                                              
          77 to 78° C.)                                            
          [disclosed in Japanese Patent                                   
          Publication 60-59159]                                           
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a comparative thermal image transfer recording medium No. 2 was obtained. 
     The above-prepared thermal image transfer recording media No. 1 to No. 8 according to the present invention and comparative thermal image transfer recording media No. 1 and No. 2 were subjected to a printing test under the following conditions: 
     Recording sheet: (1) a label-type polyester film (PET) with the back thereof treated to be adhesive, and further a release backing paper attached thereto. (2) coated paper (mirror-coat paper) 
     Thermal head : a thin-film type thermal head partially having a glaze layer. 
     Platen pressure : 150 g/cm 2   
     Peel-off angle of thermal image transfer recording medium : 30° away from a recording sheet 
     Peel-off torque : 200 g 
     Applied energy : 10 to 30 mJ/mm 2   
     Printing speed : 10 cm/sec 
     The following characteristics were measured and evaluated in the course of the printing test. 
     Thermosensitivity 
     Represented by the minimum applied energy at which fine lines transferred to the mirror-coat paper did not become blurred. 
     Friction resistance at high temperatures 
     Each printed sample was placed on a glass plate in a container where the temperature was maintained at 70° C. The printed sample was subjected to a reciprocating rubbing test by rubbing the printed surface of the sample with corrugated cardboard at a speed of 30 cm/sec, with a load of 60 g/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which images became illegible. 
     Scratch resistance to a pencil with a hardness of 2H 
     Each printed sample was rubbed by a pencil with a hardness of 2H, with a load of about 1 t/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Scratch resistance to a stainless steel edge 
     Each printed sample was rubbed by a stainless steel edge, with a load of about 1 t/cm 2  applied thereto. This characteristic was represented by the number of rubbing at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Chemical-resistance 
     Each printed sample in which images were formed on a PET film was rubbed by a cotton swab with 0.5 ml of each chemical, as listed below, absorbed, with a load of 10 g/mm 2  applied thereto. This characteristic was represented by the number of rubbing at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Chemicals 
     1. Ethanol 
     2. Brake oil 
     3. Kerosine 
     4. Compound-containing car wax 
     5. Toluene 
     6. Xylene 
     7. &#34;Perchlene&#34; for dry cleaning 
     
                                           TABLE 1                                 
__________________________________________________________________________
               Example No.                                                
               Example                                                    
               Test Items                          Comparative Example    
               1   2   3      4   5    6   7   8   1  2                   
__________________________________________________________________________
Thermosensitivity (mJ/mm.sup.2)                                           
                 25                                                       
                     26                                                   
                       25       24                                        
                                  26     25                               
                                             24                           
                                                 25                       
                                                   18 28                  
Friction resistance                                                       
           PET &gt;100                                                       
                   &gt;100                                                   
                       &gt;100   &gt;100                                        
                                  &gt;100 &gt;100                               
                                           &gt;100                           
                                               &gt;100                       
                                                   1  &gt;100(*)             
at high temperature    Appearance                     Appearance of       
(70° C.)        of scars                       stain and scars     
           Coated                                                         
               &gt;100                                                       
                   &gt;100                                                   
                       &gt;100   &gt;100                                        
                                  &gt;100 &gt;100                               
                                           &gt;100                           
                                               &gt;100                       
                                                   1  (*)                 
           paper       Appearance                     The same as         
                       of scars                       above               
Scratch resistance                                                        
           PET &gt;100                                                       
                   &gt;100                                                   
                       92     &gt;100                                        
                                  83    &gt;81                               
                                           &gt;100                           
                                               &gt;100                       
                                                   1  1                   
to a pencil with a                                                        
           Coated                                                         
               &gt;100                                                       
                   &gt; 100                                                  
                       98     &gt;100                                        
                                  87    &gt;89                               
                                           &gt;100                           
                                               &gt;100                       
                                                   1  4                   
hardness of 2H                                                            
           paper                                                          
Scratch resistance                                                        
           PET &gt;100                                                       
                   &gt;100                                                   
                       86     &gt;100                                        
                                  78    &gt;65                               
                                           &gt;100                           
                                               &gt;100                       
                                                   1  1                   
to a stainless                                                            
           Coated                                                         
               &gt;100                                                       
                   &gt;100                                                   
                       95     &gt;100                                        
                                  84    &gt;78                               
                                           &gt;100                           
                                               &gt;100                       
                                                   1  1                   
steel edge paper                                                          
Chemical-resistance                                                       
           1   &gt;100                                                       
                   &gt;100                                                   
                       &gt;100   &gt;100                                        
                                  &gt;100 &gt;100                               
                                           &gt;100                           
                                               &gt;100                       
                                                   25 36                  
           2   &gt;100                                                       
                     97                                                   
                       91     &gt;100                                        
                                  89     93                               
                                           &gt;100                           
                                               &gt;100                       
                                                   13 21                  
           3   &gt;100                                                       
                   &gt;100                                                   
                       &gt;100   &gt;100                                        
                                  &gt;100 &gt;100                               
                                           &gt;100                           
                                               &gt;100                       
                                                   3  38                  
           4   &gt;100                                                       
                   &gt;100                                                   
                       &gt;100   &gt;100                                        
                                  &gt;100 &gt;100                               
                                           &gt;100                           
                                               &gt;100                       
                                                   5  25                  
           5     63                                                       
                     54                                                   
                       58       60                                        
                                  59     46                               
                                            &gt;89                           
                                                &gt;92                       
                                                   1  3                   
           6     69                                                       
                     62                                                   
                       60       68                                        
                                  64     57                               
                                           &gt;100                           
                                               &gt;100                       
                                                   3  5                   
           7     51                                                       
                     48                                                   
                       55        48                                       
                                  57     51                               
                                            &gt;72                           
                                                &gt;81                       
                                                   3  3                   
__________________________________________________________________________
 (*)The corrugated board did not move on printed images smoothly because o
 their poor lubricating properties.                                       
 
    
     EXAMPLE 9 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              methacrylonitrile -                                         
              glycidyl acrylate                                           
              (weight ratio = 55:25:20)                                   
              [Mw = 6100, Mn = 3200)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 9 according to the present invention was obtained. 
     EXAMPLE 10 
     The procedure for Example 9 was repeated except that methyl methacrylate-methacrylonitrile-glycidyl acrylate in the ink layer coating liquid employed in Example 9 was replaced by the following terpolymer, whereby a thermal image transfer recording medium No. 10 according to the present invention was obtained. 
     Copolymer: Methyl methacrylate-acrylonitrile-glycidyl methacrylate (weight ratio by weight=45:30:25) [Mw=6900, Mn=3800) 
     EXAMPLE 11 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              methacrylonitrile -                                         
              glycidyl acrylate                                           
              (weight ratio = 55:25:20)                                   
              [Mw = 6100, Mn = 3200)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
Thermosetting BF.sub.3.C.sub.2 H.sub.5 NH.sub.2                           
                               1.5                                        
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 11 according to the present invention was obtained. 
     EXAMPLE 12 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               76                                         
              methacrylonitrile -                                         
              glycidyl acrylate                                           
              (weight ratio = 55:25:20)                                   
              [Mw = 6100, Mn = 3200)                                      
Lubricating properties-                                                   
              Silicone oil      4                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 12 according to the present invention was obtained. 
     EXAMPLE 13 
     Formation of Lubricating Properties-Imparting Agent Layer 
     Carnauba wax was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
           Carbon black     20                                            
Copolymer: Methyl methacrylate -                                          
                            70                                            
           methacrylonitrile -                                            
           glycidyl acrylate                                              
           (weight ratio = 55:25:20)                                      
           [Mw = 6100, Mn = 3200)                                         
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 13 according to the present invention was obtained. 
     EXAMPLE 14 
     Formation of Lubricating Properties-Imparting Agent Layer 
     Carnauba wax was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
           Carbon black     20                                            
Copolymer: Methyl methacrylate -                                          
                            70                                            
           methacrylonitrile -                                            
           glycidyl acrylate                                              
           (weight ratio = 55:25:20)                                      
           [Mw = 6100, Mn = 3200)                                         
Thermosetting                                                             
           BF.sub.3.C.sub.2 H.sub.5 NH.sub.2                              
                            1.5                                           
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 14 according to the present invention was obtained. 
     EXAMPLE 15 
     Formation of Adhesion-promoting Agent Layer 
     A mixture of ethylene-vinyl acetate copolymer having a melt index of 150 (40% of vinyl acetate) and carnauba wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare an adhesion-promoting agent layer coating liquid. 
     The thus prepared adhesion-promoting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 0.3 μm on a dry basis, and dried, so that an adhesion-promoting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600]                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared adhesion-promoting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 15 according to the present invention was obtained. 
     When the thus obtained thermal image transfer recording medium No. 15 was crumpled, the ink composition hardly fell off the recording medium and the adhesion promoting effect was confirmed. 
     EXAMPLE 16 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               57                                         
              methacrylonitrile -                                         
              glycidyl acrylate                                           
              (weight ratio = 55:25:20)                                   
              [Mw = 6100, Mn = 3200)                                      
Additive agents:                                                          
Flexibility-providing                                                     
              Styrene butadiene rubber                                    
                                3                                         
agent;                                                                    
Thermosensitivity-                                                        
              Linear polyester resin                                      
                               10                                         
controlling agent;                                                        
Lubricating-properties                                                    
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 16 according to the present invention was obtained. 
     EXAMPLE 17 
     The procedure for Example 7 was repeated except that glycidyl methacrylate-acrylonitrile copolymer employed in the ink layer coating liquid in Example 7 was replaced by the following terpolymer, whereby a thermal image transfer recording medium No. 17 according to the present invention was obtained. 
     Copolymer: Glycidyl methacrylate-acrylonitrile-2-hydroxyethyl methacrylate (weight ratio=50:40:10) [Mw=20000, Mn=10000] 
     The above-prepared thermal image transfer recording media No. 9 to No. 17 were subjected to the same printing test under the same conditions, as previously mentioned. 
     The following characteristics were measured and evaluated in the course of the printing test. 
     Thermosensitivity 
     Represented by the minimum applied energy at which fine lines transferred to the mirror-coat paper did not become blurred. 
     Friction resistance at high temperatures 
     Each printed sample was placed on a glass plate in a container where the temperature was maintained at 100° C. The printed sample was subjected to a reciprocating rubbing test by rubbing the printed surface of the sample with corrugated cardboard at a speed of 30 cm/sec, with a load of 60 g/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images became illegible. 
     Scratch resistance to a pencil with a hardness of 2H 
     Each printed sample was rubbed by a pencil with a hardness of 2H, with a load of about 1 t/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Scratch resistance to a stainless steel edge 
     Each printed sample was rubbed by a stainless steel edge, with a load of about 1 t/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Steam-iron resistance 
     Each printed sample was covered with a cotton cloth, with the image recorded surface thereof in contact with the cloth. A steam-iron thermostatically controlled at 150° C. was pressed on the cotton cloth for 10 seconds, under the application of a pressure of 100 g/cm 2 . According to the following scale, the rank of the steam-iron resistance of the printed images was determined by visual evaluation. 
     Estimating Scale ##STR6## 
     Heat-resistance 
     A Teflon-tape was attached to the edge of an iron thermostatically controlled at 200° C. Each printed sample was rubbed by the above iron with a load of 300 g/cm 2  applied thereto. This characteristic is represented by the number of rubbings at which the images on the printed sample became illegible. 
     Chemical-resistance 
     Each printed sample in which images were formed on a PET film was rubbed by a cotton swab with 0.5 ml of each chemical, as listed below, absorbed, with a load of 10 g/mm 2  applied thereto. This characteristic is represented by the number of rubbings at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Chemicals. 
     1. ethanol 
     2. brake oil 
     3. kerosine 
     4. compound-containing car wax 
     5. toluene 
     6. xylene 
     7. &#34;Perchlene&#34; for dry cleaning 
     
                                           TABLE 2                                 
__________________________________________________________________________
           Example No.                                                    
           Example                                                        
           Test Items                                                     
           9    10     11   12    13   14   15     16     17              
__________________________________________________________________________
Thermosensitivity                                                         
           23   25     23   23    21   21   25     21     23              
(mJ/mm.sup.2)                                                             
Friction                                                                  
       PET No   Appearance                                                
                       No   Appear-                                       
                                  No   No   Appearance                    
                                                   Appearance             
                                                          Appear-         
resistance change                                                         
                of slight                                                 
                       change                                             
                            ance of                                       
                                  change                                  
                                       change                             
                                            of slight                     
                                                   of slight              
                                                          ance of         
at high    after 100                                                      
                stain  after 100                                          
                            scars after                                   
                                  after 100                               
                                       after 100                          
                                            stain  stain  scars af-       
temperature                                                               
           cycles of                                                      
                after 100                                                 
                       cycles of                                          
                            100 cycles                                    
                                  cycles of                               
                                       cycles of                          
                                            after 100                     
                                                   after                  
                                                          ter 100         
(100° C.)                                                          
           rubbing                                                        
                cycles of                                                 
                       rubbing                                            
                            of rubbing                                    
                                  rubbing                                 
                                       rubbing                            
                                            cycles of                     
                                                   cycles                 
                                                          cycles of       
                rubbing                     rubbing                       
                                                   rubbing                
                                                          rubbing         
       Coated                                                             
           The same                                                       
                The same                                                  
                       The same                                           
                            The same                                      
                                  The same                                
                                       The same                           
                                            The same                      
                                                   The same               
                                                          The same        
       paper                                                              
           as above                                                       
                as above                                                  
                       as above                                           
                            as above                                      
                                  as above                                
                                       as above                           
                                            as above                      
                                                   as above               
                                                          as above        
Scratch resis-                                                            
       PET &gt;100 92     &gt;100 68    &gt;100 &gt; 100                              
                                            85     74     &gt;100            
tance to a                                                                
       Coated                                                             
           &gt;100 &gt;100   &gt;100 83    &gt;100 &gt;100 91     78     &gt;100            
pencil with a                                                             
       paper                                                              
hardness of                                                               
2H                                                                        
Scratch resis-                                                            
       PET 85   76     88   56    96   95   72     61     76              
tance to a                                                                
       Coated                                                             
           79   90     81   39    85   84   75     63     72              
stainless steel                                                           
       paper                                                              
edge                                                                      
Steam-iron                                                                
       PET  4    4      4    3     4    4    3      3      4              
resistance                                                                
       Coated                                                             
            3    3      4    3     3    4    3      3      4              
       paper                                                              
Heat-resis-                                                               
       PET 46   41     53   39    55   57   38     41     38              
tance  Coated                                                             
           58   47     59   46    59   59   40     46     54              
       paper                                                              
Chemical-                                                                 
       1   &gt;100 &gt;100   &gt;100 &gt;100  &gt;100 &gt;100 &gt;100   &gt;100   &gt;100            
resistance                                                                
       2   95   89     96   84    88   93   80     81     93              
       3   &gt;100 &gt;100   &gt;100 &gt;100  &gt;100 &gt;100 &gt;100   &gt;100   &gt;100            
       4   &gt;100 &gt;100   &gt;100 &gt;100  &gt;100 &gt;100 &gt;100   &gt;100   &gt;100            
       5   72   76     80   69    74   78   65     57     67              
       6   91   81     86   74    81   83   69     64     75              
       7   65   75     73   61    72   77   69     53     79              
__________________________________________________________________________
 
    
     EXAMPLE 18 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
           Carbon black      20                                           
Copolymer: Methyl methacrylate -                                          
                             70                                           
           acrylonitrile copolymer                                        
           (weight ratio = 70:30)                                         
           [Mw = 6400, Mn = 3600]                                         
Lubricating prop-                                                         
           Carnauba wax      10                                           
erties-imparting                                                          
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 2.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid containing 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 18 according to the present invention was obtained. 
     EXAMPLE 19 
     The procedure for Example 18 was repeated except that methyl methacrylate-acrylonitrile copolymer employed in the ink layer coating liquid in Example 18 was replaced by the following copolymer, whereby a thermal image transfer recording medium No. 19 according to the present invention was obtained. 
     Copolymer: Methyl methacrylate-acrylonitrile (weight ratio=50 : 50) [Mw=7700, Mn=4100] 
     EXAMPLE 20 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
           Carbon black      20                                           
Copolymer: Methyl methacrylate -                                          
                             70                                           
           acrylonitrile copolymer                                        
           (weight ratio = 70:30)                                         
           [Mw = 6400, Mn = 3600]                                         
Lubricating prop-                                                         
           Carnauba wax      10                                           
erties-imparting                                                          
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 2.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid containing 10% of solid components: 
     
         ______________________________________                                    
                  Parts by Weight                                         
______________________________________                                    
Ethylene-ethyl acrylate                                                   
                    30                                                    
copolymer (containing 25 wt. %                                            
of ethyl acrylate)                                                        
Paraffin wax        70                                                    
(melting point of 69° C.)                                          
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 20 according to the present invention was obtained. 
     EXAMPLE 21 
     Formation of Lubricating Properties-Imparting Agent Layer 
     A mixture of carnauba wax and paraffin wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
          Carbon black      20                                            
Copolymer:                                                                
          Methyl methacrylate -                                           
                            70                                            
          acrylonitrile copolymer                                         
          (weight ratio = 70:30)                                          
          [Mw = 6400, Mn = 3600]                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the lubricating properties-imparting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid containing 20% of solid components 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 0.5 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 21 according to the present invention was obtained. 
     EXAMPLE 22 
     Formation of Adhesion-promoting Agent Layer 
     A mixture of ethylene-vinyl acetate copolymer having a melt index of 150 (40% of vinyl acetate) and carnauba wax at a mixing ratio by weight of 3:7 was dispersed in toluene to prepare an adhesion-promoting agent layer coating liquid. 
     The thus prepared adhesion-promoting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 0.5 μm on a dry basis, and dried, so that an adhesion-promoting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
           Carbon black      20                                           
Copolymer: Methyl methacrylate -                                          
                             70                                           
           acrylonitrile copolymer                                        
           (weight ratio = 70:30)                                         
           [Mw = 6400, Mn = 3600]                                         
Lubricating prop-                                                         
           Carnauba wax      10                                           
erties-imparting                                                          
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared adhesion-promoting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the adhesion-promoting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid containing 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 0.5 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 22 according to the present invention was obtained. 
     When the thus obtained thermal image transfer recording medium No. 22 was crumpled, the ink composition hardly fell off the recording medium and the adhesion promoting effect was confirmed. 
     EXAMPLE 23 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
            Carbon black     20                                           
Copolymer:  Methyl methacrylate -                                         
                             57                                           
            acrylonitrile copolymer                                       
            (weight ratio = 70:30)                                        
            [Mw = 6400, Mn = 3600]                                        
Additive agents:                                                          
Flexibility-pro-                                                          
            Styrene butadiene rubber                                      
                              3                                           
viding agent;                                                             
Thermosensitivity-                                                        
            Linear polyester resin                                        
                             10                                           
controlling                                                               
agent;                                                                    
Lubricating prop-                                                         
            Carnauba wax     10                                           
erties-imparting                                                          
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 2.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid containing 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 23 according to the present invention was obtained. 
     EXAMPLE 24 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
           Carbon black      20                                           
Copolymer: Methyl methacrylate -                                          
                             70                                           
           methacrylonitrile -                                            
           glycidyl acrylate                                              
           (weight ratio = 55:25:20)                                      
           [Mw = 6100, Mn = 3200]                                         
Lubricating prop-                                                         
           Carnauba wax      10                                           
erties-imparting                                                          
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 24 according to the present invention was obtained. 
     EXAMPLE 25 
     The procedure for Example 24 was repeated except that the methyl methacrylate-methacrylonitrile-glycidyl acrylate employed in the ink layer coating liquid in Example 24 was replaced by the following copolymer, whereby a thermal image transfer recording medium No. 25 according to the present invention was obtained. 
     Copolymer: Methyl methacrylate-methacrylonitrile-glycidyl acrylate (weight ratio=45:30:25) [Mw=6900, Mn=3800] 
     EXAMPLE 26 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                          Parts by                                        
                          Weight                                          
______________________________________                                    
Coloring agent:                                                           
               Carbon black     20                                        
Copolymer:     Methyl methacrylate -                                      
                                70                                        
               methacrylonitrile -                                        
               glycidyl acrylate                                          
               (weight ratio = 55:25:20)                                  
               [Mw = 6100, Mn = 3200)                                     
Lubricating properties-                                                   
               Carnauba wax     10                                        
imparting agent:                                                          
Thermosetting agent:                                                      
               BF.sub.3.C.sub.2 H.sub.5 NH.sub.2                          
                                1.5                                       
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 26 according to the present invention was obtained. 
     EXAMPLE 27 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                          Parts by                                        
                          Weight                                          
______________________________________                                    
Coloring agent:                                                           
               Carbon black     20                                        
Copolymer:     Methyl methacrylate -                                      
                                70                                        
               methacrylonitrile -                                        
               glycidyl acrylate                                          
               (weight ratio = 55:25:20)                                  
               [Mw = 6100, Mn = 3200)                                     
Lubricating properties-                                                   
               Carnauba wax     10                                        
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 2.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethyene - ethyl acrylate                                                  
                     30                                                   
copolymer (containing 25 wt. %                                            
of ethyl acrylate)                                                        
Paraffin wax         70                                                   
(melting point of 69° C.)                                          
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 27 according to the present invention was obtained. 
     EXAMPLE 28 
     Formation of Lubricating Properties-Imparting Agent Layer 
     A mixture of carnauba wax and paraffin wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
           Carbon black     20                                            
Copolymer: Methyl methacrylate -                                          
                            70                                            
           methacrylonitrile -                                            
           glycidyl acrylate                                              
           (weight ratio = 55:25:20)                                      
           [Mw = 6100, Mn = 3200)                                         
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the lubricating properties-imparting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene - vinyl acetate                                                  
                     20                                                   
copolymer (containing 40 wt. %                                            
of vinyl acetate)                                                         
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 0.5 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 28 according to the present invention was obtained. 
     EXAMPLE 29 
     Formation of Lubricating Properties-Imparting Agent Layer 
     A mixture of carnauba wax and paraffin wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                        Parts                                             
                        by Weight                                         
______________________________________                                    
Coloring agent:                                                           
             Carbon black     20                                          
Copolymer:   Methyl methacrylate -                                        
                              70                                          
             methacrylonitrile -                                          
             glycidyl acrylate                                            
             (weight ratio = 55:25:20)                                    
             [Mw = 6100 Mn = 3200)                                        
Thermosetting agent:                                                      
             BF.sub.3.C.sub.2 H.sub.5 NH.sub.2                            
                              1.5                                         
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the lubricating properties-imparting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 29 according to the present invention was obtained. 
     EXAMPLE 30 
     Formation of Adhesion-promoting Agent Layer 
     A mixture of ethylene-vinyl acetate copolymer having a melt index of 150 (40% of vinyl acetate) and carnauba wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare an adhesion-promoting agent layer coating liquid. 
     The thus prepared adhesion-promoting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 0.3 μm on a dry basis, and dried, so that an adhesion-promoting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              methacrylonitrile -                                         
              glycidyl acrylate                                           
              (weight ratio = 55:25:20)                                   
              [Mw = 6100, Mn = 3200)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared adhesion-promoting agent layer, in a deposition amount of 3.0 μm on a dry basis, and dried, so that an ink layer was formed on the adhesion-promoting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following components were dispersed in toluene to form a thermosensitivity-promoting agent layer coating liquid 10% of solid components: 
     
         ______________________________________                                    
                   Parts by Weight                                        
______________________________________                                    
Ethylene-vinyl acetate copolymer                                          
                     20                                                   
(containing 40 wt. % of vinyl                                             
acetate)                                                                  
(melt flow rate = 70 g/min.)                                              
Carnauba wax         80                                                   
______________________________________                                    
 
    
     The thus prepared thermosensitivity-promoting agent layer coating liquid was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 30 according to the present invention was obtained. 
     When the thus obtained thermal image transfer recording medium No. 30 was crumpled, the ink composition hardly fell off the recording medium and the adhesion promoting effect was confirmed. 
     The above-prepared thermal image transfer recording media No. 18 to No. 30 were subjected to the printing test under the same conditions as employed in the test conducted in the recording media No. 1 to No. 8. The coated paper (mirror-coat paper) and art paper were employed as recording sheets for the test. The results are given in Table 3 and Table 4. 
     
                                           TABLE 3                                 
__________________________________________________________________________
               Example No.                                                
               Example                                                    
               Test Items                                                 
               18      19   20   21   22   23                             
__________________________________________________________________________
Thermosensitivity (mJ/mm.sup.2)                                           
               18      19   19   18   19   18                             
(mirror-coat paper)                                                       
Thermosensitivity (mJ/mm.sup.2)                                           
               21      22   22   21   22   21                             
(art paper)                                                               
Friction resistance                                                       
          Mirror-                                                         
               Appearance of                                              
                       The  The  The  The  The                            
at high temperature                                                       
          coat scars after                                                
                       same same same same same                           
(70° C.)                                                           
          paper                                                           
               50 cycles of                                               
                       as the                                             
                            as the                                        
                                 as the                                   
                                      as the                              
                                           as the                         
               rubbing left left left left left                           
Scratch resistance                                                        
          Mirror-                                                         
               74      70   67   78   69   68                             
to a pencil with a                                                        
          coat                                                            
hardness of 2H                                                            
          paper                                                           
Scratch resistance                                                        
          Mirror-                                                         
               31      29   25   33   21   22                             
to a stainless                                                            
          coat                                                            
steel edge                                                                
          paper                                                           
Chemical-resistance                                                       
          1    86      90   78   80   81   88                             
          2    82      87   67   70   79   94                             
          3    &gt;100    &gt;100 &gt;100 &gt;100 &gt;100 &gt;100                           
          4    &gt;100    &gt;100 &gt;100 &gt;100 &gt;100 &gt;100                           
          5    66      52   56   63   62   45                             
          6    67      68   60   70   69   57                             
          7    50      48   59   45   59   50                             
__________________________________________________________________________
 
    
     
                                           TABLE 4                                 
__________________________________________________________________________
           Example No.                                                    
           Example                                                        
           Test Items                                                     
           24     25      26     27      28     29      30                
__________________________________________________________________________
Thermosensitivity                                                         
           18     19      18     18      18     18      19                
(mJ/mm.sup.2) (mirror-                                                    
coat paper)                                                               
Thermosensitivity                                                         
           20     22      21     20      19     19      22                
(mJ/mm.sup.2)                                                             
(art paper)                                                               
Friction                                                                  
       Coated                                                             
           Appearance                                                     
                  Appearance                                              
                          Appearance                                      
                                 Appearance                               
                                         Appearance                       
                                                Appearance                
                                                        Appearance        
resistance                                                                
       paper                                                              
           of scars                                                       
                  of slight                                               
                          of scars                                        
                                 of scars                                 
                                         of scars                         
                                                of scars                  
                                                        of slight         
at high    after 50                                                       
                  scars and                                               
                          after 50                                        
                                 after 50                                 
                                         after 50                         
                                                after 50                  
                                                        scars and         
tempera-   cycles of                                                      
                  stain   cycles of                                       
                                 cycles of                                
                                         cycles of                        
                                                cycles of                 
                                                        stain after       
ture       rubbing                                                        
                  after 50                                                
                          rubbing                                         
                                 rubbing rubbing                          
                                                rubbing 50 cycles         
(70° C.)   cycles of                             of rubbing        
                  rubbing                                                 
Scratch                                                                   
       Coated                                                             
           77     75      79     69      75     76      73                
resistance                                                                
       paper                                                              
to a pen-                                                                 
cil with                                                                  
a hardness                                                                
of 2H                                                                     
Scratch                                                                   
       Coated                                                             
           36     47      40     24      41     40      32                
resistance                                                                
       paper                                                              
to a                                                                      
stainless                                                                 
steel edge                                                                
Chemical-                                                                 
       1   89     92      91     88      90     91      89                
resistance                                                                
       2   90     84      91     78      85     90      77                
       3   &gt;100   &gt;100    &gt;100   &gt;100    &gt;100   &gt;100    &gt;100              
       4   &gt;100   &gt;100    &gt;100   &gt;100    &gt;100   &gt;100    &gt;100              
       5   71     77      79     70      72     76      65                
       6   89     83      85     76      82     81      71                
       7   64     73      71     61      73     75      70                
__________________________________________________________________________
 
    
     EXAMPLE 31 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 2.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 15000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 31 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; phthalic anhydride Diol; a mixture of ethylene glycol, neopentyl glycol and trimethylolpropane at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 32 
     The procedure for Example 31 was repeated except that methyl methacrylate-acrylonitrile copolymer employed in the ink layer coating liquid in Example 31 was replaced by the following copolymer, whereby a thermal image transfer recording medium No. 32 according to the present invention was obtained. 
     Copolymer: Methyl methacrylate-acrylonitrile (weight ratio=50:50) [Mw=7700, Mn=4100] 
     EXAMPLE 33 
     The procedure for Example 31 was repeated except that the branched polyester resin employed in the thermo-sensitivity-promoting agent layer coating liquid in Example 31 was replaced by the following resin, whereby a thermal image transfer recording medium No. 33 according to the present invention was obtained. 
     Branched polyester resin having a melt viscosity of 23000 cps at 140°: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; adipic acid and phthalic anhydride Diol; a mixture of 1,6-hexanediol, ethylene glycol and trimethylol glycol at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 34 
     Formation of Lubricating Properties-Imparting Agent Layer 
     A mixture of carnauba wax and paraffin wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
           Carbon black     20                                            
Copolymer: Methyl methacrylate -                                          
                            70                                            
           acrylonitrile copolymer                                        
           (weight ratio = 70:30)                                         
           [Mw = 6400, Mn = 3600)                                         
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the lubricating properties-imparting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 23000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 0.5 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 34 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; adipic acid and phthalic anhydride Diol; a mixture of 1,6-hexanediol, ethylene glycol and trimethylol glycol at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 35 
     Formation of Adhesion-promoting Agent Layer 
     A mixture of ethylene-vinyl acetate copolymer having a melt index of 150 (40% of vinyl acetate) and carnauba wax at a mixing ratio by weight of 3:7 was dispersed in toluene to prepare an adhesion-promoting agent layer coating liquid. 
     The thus prepared adhesion-promoting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 0.5 μm on a dry basis, and dried, so that an adhesion-promoting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               70                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600]                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared adhesion-promoting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the adhesion-promoting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 15000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 0.5 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 35 according to the present invention was obtained. 
     Branched polyester resin: a condensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; phthalic anhydride Diol; a mixture of ethylene glycol, neopentyl glycol and trimethylolpropane at a mixing ratio by weight of 1:1:1. 
     When the thus obtained thermal image transfer recording medium No. 35 was crumpled, the ink composition hardly fell off the recording medium and the adhesion promoting effect was confirmed. 
     EXAMPLE 36 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl methacrylate -                                       
                               57                                         
              acrylonitrile copolymer                                     
              (weight ratio = 70:30)                                      
              [Mw = 6400, Mn = 3600]                                      
Additive agents:                                                          
Flexibility-providing                                                     
              Styrene butadiene rubber                                    
                                3                                         
agent;                                                                    
Thermosensitivity-                                                        
              Linear polyester resin                                      
                               10                                         
controlling agent;                                                        
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 2.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 15000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 36 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; phthalic anhydride Diol; a mixture of ethylene glycol, neopentyl glycol and trimethylolpropane at a mixing ratio by weight of 1:1:1. 
     The above-prepared thermal image transfer recording media No. 31 to No. 36 according to the present invention were subjected to the printing test under the same conditions as employed in the test conducted in the recording media No. 1 to No. 8. The results are given in Table 5. 
     
                                           TABLE 5                                 
__________________________________________________________________________
              Example No.                                                 
              Example                                                     
              Test Items                                                  
              31     32   33     34  35   36                              
__________________________________________________________________________
Thermosensitivity (mJ/mm.sup.2)                                           
              21     22   22     21  22   21                              
Friction resistance                                                       
          PET &gt;100   &gt;100 &gt;100   &gt;100                                     
                                     &gt;100 &gt;100                            
at high temperature                                                       
              Appearance  Appearance                                      
(70° C.)                                                           
              of scars    of scars                                        
          Coated                                                          
              &gt;100   &gt;100 &gt;100   &gt;100                                     
                                     &gt;100 &gt;100                            
          paper           Appearance                                      
                          of scars                                        
Scratch resistance                                                        
          PET &gt;100   &gt;100 88     &gt;100                                     
                                     85   80                              
to a pencil with a                                                        
          Coated                                                          
              &gt;100   &gt;100 91     &gt;100                                     
                                     89   84                              
hardness of 2H                                                            
          paper                                                           
Scratch resistance                                                        
          PET   81     85 70       92                                     
                                     75   65                              
to a stainless                                                            
          Coated                                                          
              &gt;100   &gt;100 90     &gt;100                                     
                                     79   79                              
steel edge                                                                
          paper                                                           
Chemical-resistance                                                       
          1     86     90 73       80                                     
                                     81   88                              
          2     82     87 67       70                                     
                                     79   94                              
          3   &gt;100   &gt;100 &gt;100   &gt;100                                     
                                     &gt;100 &gt;100                            
          4   &gt;100   &gt;100 &gt;100   &gt;100                                     
                                     &gt;100 &gt;100                            
          5     66     52 56       63                                     
                                     62   45                              
          6     67     68 66       70                                     
                                     69   57                              
          7     50     48 59       45                                     
                                     59   60                              
__________________________________________________________________________
 
    
     EXAMPLE 37 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl acrylate -                                           
                               70                                         
              acrylonitrile -                                             
              glycidyl methacrylate                                       
              (weight ratio = 55:25:20)                                   
              [Mw = 6000, Mn = 3000)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 15000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 37 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; phthalic anhydride Diol; a mixture of ethylene glycol, neopentyl glycol and trimethylolpropane at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 38 
     The procedure for Example 37 was repeated except that methyl acrylate-acrylonitrile-glycidyl methacrylate in the ink layer coating liquid employed in Example 37 was replaced by the following copolymer, whereby a thermal image transfer recording medium No. 38 according to the present invention was obtained. 
     Copolymer: Methyl acrylate-acrylonitrile-glycidyl methacrylate (weight ratio=45:30:25) [Mw=6900, Mn=3800] 
     EXAMPLE 39 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl acrylate -                                           
                               70                                         
              acrylonitrile -                                             
              glycidyl methacrylate                                       
              [weight ratio = 55:25:20)                                   
              [Mw = 6000, Mn = 3000)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
Thermosetting agent:                                                      
              BF.sub.3.C.sub.2 H.sub.5 NH.sub.2                           
                               1.5                                        
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 3.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 15000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 39 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; phthalic anhydride Diol; a mixture of ethylene glycol, neopentyl glycol and trimethylolpropane at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 40 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl acrylate -                                           
                               70                                         
              acrylonitrile -                                             
              glycidyl methacrylate                                       
              (weight ratio = 55:25:20)                                   
              [Mw = 6000, Mn = 3000)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 2.0 μm on a dry basis, and dried, so that an ink layer was formed on the substrate. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 23000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 40 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; adipic acid and phthalic anhydride Diol; a mixture of 1,6-hexanediol, ethylene glycol and trimethylol glycol at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 41 
     Formation of Lubricating Properties-Imparting Agent Layer 
     A mixture of carnauba wax and paraffin wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                      Parts by Weight                                     
______________________________________                                    
Coloring agent:                                                           
           Carbon black     20                                            
Copolymer: Methyl acrylate -                                              
                            70                                            
           acrylonitrile -                                                
           glycidyl methacrylate                                          
           (weight ratio =                                                
           55:25:20)                                                      
           [Mw = 6000, Mn = 3000)                                         
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the lubricating properties-imparting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 23000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 0.5 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 41 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; adipic acid and phthalic anhydride Diol; a mixture of 1,6-hexanediol, ethylene glycol and trimethylol glycol at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 42 
     Formation of Lubricating Properties-Imparting Agent Layer 
     A mixture of carnauba wax and paraffin wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare a lubricating properties-imparting agent layer coating liquid. 
     The thus prepared lubricating properties-imparting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 1.0 μm on a dry basis, and dried, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
             Carbon black      20                                         
Copolymer:   Methyl acrylate - 70                                         
             acrylonitrile -                                              
             glycidyl methacrylate                                        
             (weight ratio =                                              
             55:25:20)                                                    
             [Mw = 6000, Mn = 3000)                                       
Thermosetting agent:                                                      
             BF.sub.3.C.sub.2 H.sub.5 NH.sub.2                            
                               1.5                                        
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, so that an ink layer was formed on the lubricating properties-imparting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 15000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 42 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; phthalic anhydride Diol; a mixture of ethylene glycol, neopentyl glycol and trimethylolpropane at a mixing ratio by weight of 1:1:1. 
     EXAMPLE 43 
     Formation of Adhesion-promoting Agent Layer 
     A mixture of ethylene-vinyl acetate copolymer having a melt index of 150 (40% of vinyl acetate) and carnauba wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare an adhesion-promoting agent layer coating liquid. 
     The thus prepared adhesion-promoting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, in a deposition amount of 0.3 μm on a dry basis, and dried, so that an adhesion-promoting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in methyl ethyl ketone to prepare an ink layer coating liquid containing 20% of solid components: 
     
         ______________________________________                                    
                         Parts                                            
                         by Weight                                        
______________________________________                                    
Coloring agent:                                                           
              Carbon black     20                                         
Copolymer:    Methyl acrylate -                                           
                               70                                         
              acrylonitrile -                                             
              glycidyl methacrylate                                       
              (weight ratio =                                             
              55:25:20)                                                   
              [Mw = 6000, Mn = 3000)                                      
Lubricating properties-                                                   
              Carnauba wax     10                                         
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared adhesion-promoting agent layer, in a deposition amount of 3.0 μm on a dry basis, and dried, so that an ink layer was formed on the adhesion-promoting agent layer. 
     Thermosensitivity-promoting Agent Layer 
     The following branched polyester resin having a melt viscosity of 15000 cps at 140° C. was coated on the above-prepared ink layer in a deposition amount of 1.0 μm to form a thermosensitivity-promoting agent layer, whereby a thermal image transfer recording medium No. 43 according to the present invention was obtained. 
     Branched polyester resin: a polycondensation product of the following dibasic acid and diol at a mixing ratio by weight of 50:50. 
     Dibasic acid; phthalic anhydride Diol; a mixture of ethylene glycol, neopentyl glycol and trimethylolpropane at a mixing ratio by weight of 1:1:1. 
     When the thus obtained thermal image transfer recording medium No. 43 was crumpled, the ink composition hardly fell off the recording medium and the adhesion promoting effect was confirmed. 
     The above-prepared thermal image transfer recording media No. 37 to No. 43 were subjected to the printing test under the same conditions as employed in the test conducted in the recording media No. 9 to No. 17. The results are given in Table 6. 
     
                                           TABLE 6                                 
__________________________________________________________________________
           Example No.                                                    
           Example                                                        
           Test Items                                                     
           37     38      39     40      41     42      43                
__________________________________________________________________________
Thermosensitivity                                                         
           20     22      21     20      19     19      22                
(mJ/mm.sup.2)                                                             
Friction                                                                  
       PET Appearance                                                     
                  Appearance                                              
                          Appearance                                      
                                 Appearance                               
                                         Appearance                       
                                                Appearance                
                                                        Appearance        
resistance of scars                                                       
                  of slight                                               
                          of scars                                        
                                 of scars                                 
                                         of scars                         
                                                of scars                  
                                                        of slight         
at high    after 100                                                      
                  stain and                                               
                          after 100                                       
                                 after 100                                
                                         after 100                        
                                                after 100                 
                                                        scars and         
tempera-   cycles of                                                      
                  scars   cycles of                                       
                                 cycles of                                
                                         cycles of                        
                                                cycles of                 
                                                        stain after       
ture       rubbing                                                        
                  after 100                                               
                          rubbing                                         
                                 rubbing rubbing                          
                                                rubbing 100 cycles        
(100° C.)  cycles of                             of rubbing        
                  rubbing                                                 
       Coated                                                             
           No change                                                      
                  Appearance                                              
                          No change                                       
                                 The same                                 
                                         No change                        
                                                No change                 
                                                        Appearance        
       paper                                                              
           after 100                                                      
                  of slight                                               
                          after 100                                       
                                 as above                                 
                                         after 100                        
                                                after 100                 
                                                        of slight         
           cycles of                                                      
                  stain   cycles of      cycles of                        
                                                cycles of                 
                                                        stain after       
           rubbing                                                        
                  after 100                                               
                          rubbing        rubbing                          
                                                rubbing 100 cycles        
                  cycles of                             of rubbing        
                  rubbing                                                 
Scratch                                                                   
       PET &gt;100   98      &gt;100   67      &gt;100   &gt;100    87                
resistance                                                                
       Coated                                                             
           &gt;100   &gt;100    &gt;100   83      &gt;100   &gt;100    91                
to a pen-                                                                 
       paper                                                              
cil with                                                                  
a hardness                                                                
of 2H                                                                     
Scratch                                                                   
       PET 80     72      83     51      94     91      68                
resistance                                                                
       Coated                                                             
           76     87      80     34      81     80      72                
to a   paper                                                              
stainless                                                                 
steel edge                                                                
Steam-iron                                                                
       PET  4      4       4      3       4      4       3                
resistance                                                                
       Coated                                                             
            3      3       4      3       3      4       3                
       paper                                                              
Heat-  PET 44     40      54     38      54     55      36                
resistance                                                                
       Coated                                                             
           59     46      56     45      60     58      42                
       paper                                                              
Chemical-                                                                 
       1   89     92      91     88      90     91      89                
resistance                                                                
       2   90     84      91     78      85     90      77                
       3   &gt;100   &gt;100    &gt;100   &gt;100    &gt;100   &gt;100    &gt;100              
       4   &gt;100   &gt;100    &gt;100   &gt;100    &gt;100   &gt;100    &gt; 100             
       5   71     77      79     70      72     76      65                
       6   89     83      85     76      82     81      71                
       7   64     73      71     61      73     75      70                
__________________________________________________________________________
 
    
     EXAMPLE 44 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in 800 parts by weight of methyl ethyl ketone to prepare an ink layer coating liquid: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
          Carbon black       30                                           
Copolymer:                                                                
          Alkanolamine-modified                                           
                             145                                          
          polymer of formula (III):                                       
 ##STR7##                     (III)                                       
          wherein R.sup.1, R.sup.2 and R.sup.4 each                       
          represent CH.sub.3 ; R.sup.3 represents                         
          H; and R.sup.5 and R.sup.6 each                                 
          represent C.sub.2 H.sub.4 OH.                                   
          (weight ratio of l:m:n:x =                                      
          30:45:25:0)                                                     
          [Mw = 5300, Mn = 2300]                                          
Lubricating                                                               
          Carnauba wax       25                                           
properties-                                                               
imparting agent:                                                          
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, with a heat-resistant backing layer attached thereto, in a deposition amount of 3.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 44 according to the present invention was obtained. 
     The ink layer was sufficiently flexible and there were no curling problems. 
     EXAMPLE 45 
     Formation of Lubricating Properties-imparting Agent Layer 
     A mixture of carnauba wax and a paraffin wax having a melting point of 69° C. at a mixing ratio by weight of 3:7 was coated by hot-melt coating on a polyester film having a thickness of 4.5 μm serving as a substrate, with a heat-resistant backing layer attached thereto, in a deposition amount of 1.0 μm, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     The same ink layer coating liquid as prepared in Example 44 was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 45 according to the present invention was obtained. 
     EXAMPLE 46 
     Formation of Lubricating Properties-imparting Agent Layer 
     A mixture of carnauba wax and a paraffin wax having a melting point of 69° C. at a mixing ratio by weight of 3:7 was coated by hot-melt coating on a polyester film serving as a substrate with a thickness of 4 5 μm, with a heat-resistant backing layer attached thereto, in a deposition amount of 1.0 μm, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in 800 parts by weight of methyl ethyl ketone to prepare an ink layer coating liquid: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
          Carbon black       30                                           
Copolymer:                                                                
          Alkanolamine-modified                                           
                             127                                          
          polymer of formula (III):                                       
 ##STR8##                     (III)                                       
          wherein R.sup.1, R.sup.2 and R.sup.4 each                       
          represent CH.sub.3 ; R.sup.3 represents                         
          H; and R.sup.5 and R.sup.6 each                                 
          represent C.sub.2 H.sub.4 OH.                                   
          (weight ratio of l:m:n:x =                                      
          30:45:25:0)                                                     
          [Mw = 5300, Mn = 2300]                                          
Blocked   Adduct of 2,4-tolylene                                          
                             43                                           
isocyanate:                                                               
          diisocyanate with                                               
          trimethylolpropane;                                             
          (methyl ethyl ketone                                            
          oxime block)                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 46 according to the present invention was obtained. 
     EXAMPLE 47 
     Formation on of Lubricating Properties-imparting Agent Layer 
     A mixture of carnauba wax and a paraffin wax having a melting point of 69° C. at a mixing ratio by weight of 3:7 was coated by means of the hot-melt coating on a polyester film serving as a substrate with a thickness of 4.5 μm, with a heat-resistant backing layer attached thereto, in a deposition amount of 1.0 μm, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in 800 parts by weight of methyl ethyl ketone to prepare an ink layer coating liquid: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
          Carbon black       30                                           
Copolymer:                                                                
          Alkanolamine-modified                                           
                             136                                          
          polymer of formula (III):                                       
 ##STR9##                     (III)                                       
          wherein R.sup.1, R.sup.2 and R.sup.4 each                       
          represent CH.sub.3 ; R.sup.3 represents                         
          H; and R.sup.5 and R.sup.6 each                                 
          represent C.sub.2 H.sub.4 OH.                                   
          (weight ratio of l:m:n:x =                                      
          30:45:15:10)                                                    
          [Mw = 5800, Mn = 2500]                                          
Blocked   Adduct of 2,4-tolylene                                          
                             34                                           
isocyanate:                                                               
          diisocyanate with                                               
          trimethylolpropane;                                             
          (methyl ethyl ketone                                            
          oxime block)                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 47 according to the present invention was obtained. 
     EXAMPLE 48 
     Formation of Lubricating Properties-imparting Agent Layer 
     A mixture of carnauba wax and a paraffin wax having a melting point of 69° C. at a mixing ratio by weight of 3:7 was coated by hot-melt coating on a polyester film serving as a substrate with a thickness of 4.5 μm, with a heat-resistant backing layer attached thereto, in a deposition amount of 1.0 μm, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in 800 parts by weight of methyl ethyl ketone to prepare an ink layer coating liquid: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
          Carbon black       30                                           
Copolymer:                                                                
          Alkanolamine-modified                                           
                             135                                          
          polymer of formula (III):                                       
 ##STR10##                    (III)                                       
          wherein R.sup.1, R.sup.2 and R.sup.4 each                       
          represent CH.sub.3 ; R.sup.3 represents                         
          H; and R.sup.5 and R.sup.6 each                                 
          represent C.sub.2 H.sub.4 OH.                                   
          (weight ratio of l:m:n:x =                                      
          30:45:15:10)                                                    
          [Mw = 5800, Mn = 2500]                                          
Blocked   Adduct of 2,4-tolylene                                          
                             30                                           
isocyanate:                                                               
          diisocyanate with                                               
          trimethylolpropane;                                             
          (methyl ethyl ketone                                            
          oxime block)                                                    
Thermosetting                                                             
          BF.sub.3.C.sub.2 H.sub.5 NH.sub.2                               
                              5                                           
agent:                                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 48 according to the present invention was obtained. 
     EXAMPLE 49 
     Formation of Adhesion-promoting Agent Layer 
     A mixture of ethylene-vinyl acetate copolymer having a melt index of 150 (40% of vinyl acetate) and carnauba wax at a mixing ratio by weight of 1:1 was dispersed in toluene to prepare an adhesion-promoting agent layer coating liquid. 
     The thus prepared adhesion-promoting agent layer coating liquid was coated on a polyester film serving as a substrate with a thickness of 4.5 μm, with a heat-resistant backing layer attached thereto, in a deposition amount of 0.5 μm on a dry basis, and dried, so that an adhesion-promoting agent layer was formed on the substrate. 
     The same ink layer coating liquid as prepared in Example 48 was coated on the above-prepared adhesion-promoting agent layer, in a deposition amount of 2.5 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 49 according to the present invention was obtained. 
     EXAMPLE 50 
     Formation of Lubricating Properties-imparting Agent Layer 
     A mixture of carnauba wax and a paraffin wax having a melting point of 69° C. at a mixing ratio by weight of 3:7 was coated by hot-melt coating on a polyester film serving as a substrate with a thickness of 4.5 μm, with a heat-resistant backing layer attached thereto, in a deposition amount of 1.0 μm, so that a lubricating properties-imparting agent layer was formed on the substrate. 
     Formation of Ink Layer 
     A mixture of the following components was dispersed in 800 parts by weight of methyl ethyl ketone to prepare an ink layer coating liquid: 
     
         ______________________________________                                    
                       Parts by Weight                                    
______________________________________                                    
Coloring agent:                                                           
          Carbon black       30                                           
Copolymer:                                                                
          Alkanolamine-modified                                           
                             116                                          
          polymer of formula (III):                                       
 ##STR11##                    (III)                                       
          wherein R.sup.1, R.sup.2 and R.sup.4 each                       
          represent CH.sub.3 ; R.sup.3 represents                         
          H; and R.sup.5 and R.sup.6 each                                 
          represent C.sub.2 H.sub.4 OH.                                   
          (weight ratio of l:m:n:x =                                      
          30:45:15:10)                                                    
          [Mw = 100,000, Mn = 48,000]                                     
Blocked   Adduct of 2,4-tolylene                                          
                             34                                           
isocyanate:                                                               
          diisocyanate with                                               
          trimethylolpropane;                                             
          (methyl ethyl ketone                                            
          oxime block)                                                    
______________________________________                                    
 
    
     The thus prepared ink layer coating liquid was coated on the above-prepared lubricating properties-imparting agent layer, in a deposition amount of 2.0 μm on a dry basis, and dried, whereby a thermal image transfer recording medium No. 50 according to the present invention was obtained. 
     The above-prepared thermal image transfer recording media No. 44 to No. 50 according to the present invention were subjected to a printing test under the following conditions: 
     Recording sheet : (1) a label-type polyester film (PET) with the back thereof treated so as to be adhesive, and a release backing paper attached thereto. (2) coated paper (mirror-coat paper) 
     Thermal head : a thin-film type thermal head partially having a glaze layer. 
     Platen pressure : 150 g/cm 2   
     Peel-off angle of thermal image transfer recording medium : 30° away from a recording sheet 
     Peel-off torque : 200 g 
     Applied energy : 10 to 30 mJ/mm 2   
     Printing speed : 10 cm/sec 
     The following characteristics were measured and evaluated in the course of the printing test. 
     Thermosensitivity 
     Represented by the minimum applied energy at which fine lines transferred to the mirror-coat paper did not become blurred. 
     Friction resistance at high temperatures 
     Each printed sample in which images were formed on the mirror-coat paper was placed on a glass plate in a container where the temperature was maintained at 100° C. The printed sample was subjected to a reciprocating rubbing test by rubbing the printed surface of the sample with a corrugated cardboard at a speed of 30 cm/sec, with a load of 100 g/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images became illegible. 
     Scratch resistance to a pencil with a hardness of 2H 
     Each printed sample in which images were formed on the mirror-coat paper was rubbed by a pencil with a hardness of 2H, with a load of about 1 t/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Scratch resistance to a stainless steel edge 
     Each printed sample in which images were formed on the mirror-coat paper was rubbed by a stainless steel edge, with a load of about 1 t/cm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Chemical-resistance 
     Each printed sample in which images were formed on a PET film was rubbed by a cotton swab with 0.5 ml of each chemical, as listed below, absorbed, with a load of 30 g/mm 2  applied thereto. This characteristic was represented by the number of rubbings at which printed images were scraped off the recording sheet and the recording sheet was exposed. 
     Chemicals 
     1. ethanol 
     2. brake oil 
     3. kerosine 
     4. compound-containing car wax 
     5. toluene 
     6. xylene 
     7 &#34;Perchlene&#34; for dry cleaning 
     
                                           TABLE 7                                 
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              Example No.                                                 
              Examples                                                    
              Test Items                                                  
              44   45   46   47  48  49  50                               
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Thermosensitivity (mJ/mm.sup.2)                                           
              23   20   20     21                                         
                                   21                                     
                                       23                                 
                                           30                             
(mirror-coat paper)                                                       
Friction resistance at                                                    
              &gt;100 &gt;100 &gt;100 &gt;100                                         
                                 &gt;100                                     
                                     &gt;100                                 
                                         &gt;100                             
high temperature (100° C.)                                         
(mirror-coat paper)                                                       
Scratch resistance to a                                                   
              78   84   &gt;100 &gt;100                                         
                                 &gt;100                                     
                                     &gt;100                                 
                                         &gt;100                             
pencil with a hardness of                                                 
2H (mirror-coat paper)                                                    
Scratch resistance to a                                                   
              65   76   &gt;100 &gt;100                                         
                                 &gt;100                                     
                                     &gt;100                                 
                                         &gt;100                             
stainless steel edge                                                      
(mirror-coat paper)                                                       
Chemical-resistance                                                       
           1  61   66   85     94                                         
                                   98                                     
                                       91                                 
                                         &gt;100                             
(PET)      2  94   85   96   &gt;100                                         
                                 &gt;100                                     
                                     &gt;100                                 
                                         &gt;100                             
           3  &gt;100 &gt;100 &gt;100 &gt;100                                         
                                 &gt;100                                     
                                     &gt;100                                 
                                         &gt;100                             
           4  &gt;100 &gt;100 &gt;100 &gt;100                                         
                                 &gt;100                                     
                                     &gt;100                                 
                                         &gt;100                             
           5  59   62   75     84                                         
                                   89                                     
                                      &gt;82                                 
                                           96                             
           6  85   78   92   &gt;100                                         
                                 &gt;100                                     
                                     &gt;100                                 
                                         &gt;100                             
           7  43   49   68     75                                         
                                   88                                     
                                      &gt;86                                 
                                         &gt;100                             
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     As previously explained, since the thermal image transfer recording media according to the present invention have an ink layer comprising a copolymer of acrylonitrile or methacrylonitrile, images transferred from the same onto a recording sheet show the remarkably improved friction and scratch resistance, in particular, to a hard object, and chemical resistance. Accordingly, the thermal image transfer recording media according to the present invention can produce highly reliable images for use in practice.