Water-dispersible dye/resin compositions
This is a continuation of Application Ser. No. 580,082 filed May 22, 1975 and now abandoned. 
    
    
     This invention concerns solutions (term as used herein includes true solution, colloidal dispersion and suspension) of disperse dyes in water-dispersible copolyesters, such as those containing 5-sodiosulfoisophthalic acid moiety, in solid, semi-solid or viscous liquid form, which solutions are particularly useful for preparing water-based heat transfer printing inks. 
     In the manufacture of disperse dyes for use in heat transfer printing inks or for use in conventional dyeing, the customary practice is to grind or ball mill the disperse dye with dispersing aids for extended periods to reduce its primary particle to less than about 25 microns and insure at least a reasonably stable dye suspension in the aqueous bath. This procedure is costly, time consuming and inconvenient. 
     An object, therefore, of the present invention is to provide means and process for making stable dispersions of nonionic dyes in water without the aforesaid ball milling or grinding step. This and other objects hereinafter becoming evident have been attained in accordance with the present invention through the development of solutions or extremely fine dispersions of nonionic dyes in certain water-dispersible copolyester materials, which can be dissolved subsequently in water to give reasonably stable, homogeneous suspensions of dye in water. 
     It is quite surprising that large quantities of disperse dye can be dissolved in the water-dispersible resins and carried over into water in finely dispersed form by the simple step of dissolving the copolyester in water. A useful ratio of dye to resin is from about 1/20 to about 3/2 by weight, with the preferred ratio being from about 1/4 to about 4/3. The dye/resin compositions dispersed in water may be thickened with conventional thickening agents to produce printing pastes or inks suitable for textiles or paper. 
     Useful water-dispersible copolyesters and their preparations are described for example in U.S. Pat. Nos. 3,734,874 and 3,546,008, hereby incorporated by reference as a part of the present specification, particularly the dicarboxylic acids, the diols, the poly(ethylene glycols), and the dicarboxylic acids having the --SO 3  M group, disclosed in Columns 3, 4 and 5 of each said patents. These copolyesters may be defined as water-dispersible polyester reaction products of at least one acid selected from aliphatic acids of from about 6 to about 30 carbons, cycloaliphatic acids of from about 4 to about 12 carbons, and aromatic dicarboxylic acids of from about 6 to about 14 carbons, a diol component of from about 2 to about 28 carbons, at least 20 mole percent of which is a poly(ethylene glycol) having the formula 
     
         H--(OCH.sub.2 CH.sub.2)--.sub.n OH 
    
     wherein n is an integer of from 2 to about 14, and at least one dicarboxylic acid constituting from about 8 mole percent to about 45 mole percent of the total moles of said diol component and containing a --SO 3  M group attached to an aromatic nucleus, wherein M is hydrogen or a metal ion. 
     The solutions or dispersions of dye in the copolyesters may be obtained by melt blending the dye with molten polymer. In such a process, dicarboxylic acids, preferably adipic, as described in U.S. Pat. No. 3,853,820, the disclosure of which is incorporated into this specification by reference, may be added in the desired quantity to adjust the polymer melt viscosity as detailed in Example 2 below. The melt viscosity of the system into which the dye is fed preferably should be between about 1000-2000 centipoise at the dye dissolution temperature selected which must be below the decomposition temperature of the dye but above the melting point of the aliphatic or alicyclic dicarboxylic acid. 
     A preferred blending technique is to roll mill the dye into softened polymer as detailed in Example 6 below, and thus obviate the need for adjusting melt viscosity with modifying acids. The roll milling is more fully described in copending U.S. patent application Ser. No. 560,760, in the names of Samuel E. Blackwell and Glenna B. Bowen, incorporated herein by reference. The gist of that process is that dye cake principally of a primary particle size of above about 50 microns is roll-milled with heat softenable polymeric material in the ratio of from about 1/40 to about 4/1 parts by weight of dye cake to polymeric material, wherein the roll gap is at least about 0.001 inch, and preferably more than about 0.06 inch, for a sufficient period to obtain a significant reduction in dye particle size. In the present invention, the dye will actually dissolve in the copolyester. The roll gap may be as in commercial size equipment, up to 1/2 inch or more depending on the viscosity and feed rate of the copolyester, and canted rolls, where the gap is wider on one end than on the other, may be employed. 
     The present invention may be defined as water-dispersible compositions comprising: 
     (A) from about 5 to about 60% by weight of disperse dye, and 
     (B) from about 95 to about 40% by weight of linear, water-dispersible copolyester, or 
     (C) from 95 to about 40% by weight of a blend of the copolyester of (B) with up to about 40% by weight based on total weight of said blend of a saturated aliphatic or cycloaliphatic dicarboxylic acid having 6 to 12 carbon atoms, 
     said copolyester being comprised of 
     (D) at least one aliphatic, cycloaliphatic or aromatic dicarboxylic acid component, 
     (E) a diol component of from about 2 to about 28 carbons, at least about 20 mole percent of which is a poly(ethylene glycol) having the formula H--(OCH 2  CH 2 ) n  OH wherein n is an integer of from 2 to about 14, and 
     (F) at least one difunctional dicarboxylic acid containing a --SO 3  M group attached to an aromatic nucleus, wherein M is hydrogen, Na + , Li +   or K + , and constituting at least about 8 mole percent to about 45 mole percent of the total moles of components (D) and (F). 
     The dye/resin compositions in, for example, chip form of any convenient size and shape may be dispersed in water directly from a molten state, or alternatively, the solutions may be cooled and solidified, broken into convenient sized chips, and dispersed in water at some later time. The solutions prepared by roll milling may also be cooled and broken into chips as in Example 6. In either case, the compositions of this invention provide a unique and novel means for dispersing water-insoluble disperse dyes in water to obtain a very small dye particle size without the necessity of an extensive grinding or ball milling operation. 
     The water-dispersible copolyesters of 5-sodiosulfoisophthalic acid may be melt or otherwise blended with conventional additives, such as up to about 15% by weight of antiblocking agents including C 12  -C 22  fatty acids and derivatives thereof, to facilitate storage of the dye/resin solution in chip or granular form. Examples of such fatty acids are stearic, oleic, and palmitic. Derivatives of fatty acids such as amides, esters and imidazolines also may be used. Such derivatives include methyl, palmitate, stearamide, 12-hydroxystearic acid, and N,N&#39;-ethylene bisstearamide. The preferred antiblocking agent is stearic acid. Small amounts of pigments such as talc also may be used in the blend to reduce the blocking tendency of chips or granules thereof. Minor amounts of up to about 10% by weight of other additives such as antistatic agents and antioxidants may also be incorporated into the copolyester per se or the resin blend to achieve desired results. 
     Specifically, the preferred water-dispersible polyesters useful in the practice of this invention are reaction products of isophthalic acid, 5-sodiosulfoisophhthalic acid, and poly(oxyethylene glycols). A preferred group of copolyesters are comprised of an acid component comprising 80-90 mole % of isophthalic acid, 5-20 mole % of 5-sodiosulfoisophthalic acid, and diethylene glycol as the diol. Most preferred polyesters include the copolyesters of 90-92 mole % isophthalic acid and 8-10 mole % 5-sodiosulfoisophthalic acid as the acid moiety, and diethylene glycol, and the copolyesters of isophthalic acid with 13-17 mole % of 5-sodiosulfoisophthalic acid, and diethylene glycol with 28-32 mole % of 1,4-cyclohexanedimethanol. Listed in the following Table I are examples of useful copolyesters. 
     
                                           TABLE I                                 
__________________________________________________________________________
            Mole       Mole      Mole                                     
Dicarboxylic Acid                                                         
            Percent                                                       
                 Sulfonate                                                
                       Percent                                            
                            Diol Percent                                  
                                      I.V.                                
__________________________________________________________________________
Isophthalic 52.5)      7.5  DEG.sup.12                                    
                                 100  0.54                                
Terephthalic                                                              
            25)   SIP                                                     
Hexahydroisophthalic                                                      
            15)                                                           
Isophthalic 90   SIP   10   DEG  100  0.53                                
Hexahydroterephthalic                                                     
            90   SIP   10   DEG  100  0.73                                
Isophthalic 50)             (DEG 80)                                      
Terephthalic                                                              
            25)  SIP   10   (EG.sup.3                                     
                                 20)  0.60                                
Hexahydroisophthalic                                                      
            15)                                                           
Isophthalic 50)                                                           
Terephthalic                                                              
            25)  (4)   10   DEG  100  0.42                                
Hexahydroisophthalic                                                      
            15)                                                           
Isophthalic 90   (5)   10   DEG  100  0.48                                
Isophthalic 60)  (5)   10   DEG  100  0.55                                
Hexahydroterephthalic                                                     
            30)                                                           
Isophthalic 90   (6)   10   DEG  100  0.42                                
Terephthalic                                                              
            92   SIP   8    TEG.sup.7                                     
                                 100  0.33                                
Isophthalic 92   SIP   8    TEG  100  0.59                                
                            (CHDM.sup.8                                   
                                 30)                                      
&#34;90         SIP  10    (DEG 70)  0.45                                     
Adipic      90   SIP   10   DEG  100  0.69                                
                            (CHDM                                         
                                 50)                                      
Isophthalic 90   SIP   10   (DEG 50)  0.48                                
                            (CHDM                                         
                                 60)                                      
&#34;           90   SIP   10   (DEG 40)  0.51                                
                            (CHDM                                         
                                 70)                                      
&#34;80         SIP  20    (DEG 30)  0.32                                     
                            (CHDM                                         
                                 60)  0.38                                
∝80  SIP  20    (DEG 40)                                           
 .sup.1 SIP--5-sodiosulfoisophthalic acid.                                
.sup.2 DEG--diethylene glycol.                                            
.sup.3 EG--ethylene glycol.                                               
.sup.4 4-sodiosulfophenyl-3,5-dicarboxybenzene sulfonate.                 
 ##STR1##                                                                 
.sup.5 5-[4-(sodiosulfo)phenoxy]isophthalic acid.                         
 ##STR2##                                                                 
.sup.6 2(2-sodiosulfophenyl)-2-ethylmalonic acid.                         
 ##STR3##                                                                 
.sup.7 TEG--triethylene glycol.                                           
.sup.8 CHDM--1,4-cyclohexanedimethanol.                                   
__________________________________________________________________________
 
    
     Dyes useful in this invention are those classified by the Colour Index as disperse colors. They may be of any chemical class such as ezo, anthraquinone, methine, and disazo, which are characterized by the absence of any pendant water solubilizing groups such as a sulfonic acid group or a salt thereof. Of particular interest for heat transfer printing uses are those dyes which sublime readily at 180°-230° C., exemplified by C.I. Disperse Yellow 3, Disperse Yellow 85, Disperse Yellow 23, Disperse Orange 25, Disperse Red 60, Disperse Red 4, Disperse Red 78, Disperse Violet 1, Disperse Violet 27, Disperse Blue 3, Disperse Blue 14, and Disperse Blue 35. 
     Two or more disperse dyes may be blended in the same resin, if desired, to produce a resultant color, provided that no adverse chemical reaction between the dyes or the resin occurs at the dye dissolution temperature. Alternatively, two or more dye/resin solutions may be dispersed in the same printing paste. 
    
    
     EXAMPLE 1--Preparation of Water-Dispersible Resin 
     Sixty parts of the 90/10 copolyester of isophthalic acid/5-sodiosulfoisophthalic acid, and diethylene glycol (inherent viscosity 0.39) are mixed with 40 parts of adipic acid and 10 parts of stearic acid at 165° C. under an atmosphere of dry nitrogen until all solid materials have melted and the blend is homogeneous. The blend is then extruded onto granules of solid carbon dioxide and ground to about 3 mm. particle size in a Wiley mill. The inherent viscosity of the blend corrected for the low-molecular-weight diluents, adipic and stearic acids, is 0.38. 
     In the same manner as described above, the resin blends shown in Table II below are prepared. 
     
                                           Table II                                
__________________________________________________________________________
Examples of Resins Useful for Preparing Water-Dispersible Solutions of    
Dyes                                                                      
Resin              Parts                                                  
                       Dicarboxylic                                       
                              Parts                                       
                                  Antiblocking                            
                                         Parts                            
No. Water-Dispersible Polyester                                           
                   by Wt.                                                 
                       Acid   by Wt.                                      
                                  Agent  by Wt.                           
__________________________________________________________________________
1   90/10 isophthalic acid/5-sodio-                                       
                   60  Adipic 40  Stearic acid                            
                                         10                               
    sulfoisophthalic acid and                                             
    diethylene glycol                                                     
2   90/10 isophthalic acid/5-sodio-                                       
                   60  Sebacic                                            
                              40  --     --                               
    sulfoisophthalic acid and                                             
    diethylene glycol                                                     
3   90/10 isophthalic acid/5-sodio-                                       
                   60  Adipic 40  --     --                               
    sulfoisophthalic acid and                                             
    dietylene glycol                                                      
4   92/8 isophtahlic acid/5-sodio-                                        
                   55  Adipic 45  Palmitic acid                           
                                         5                                
    sulfoisophthalic acid and                                             
    diethylene glycol                                                     
5   92/8 isophthalic acid/5-sodio-                                        
                   60  Azelaic                                            
                              40  N,N&#39;-ethylene                           
                                         2.5                              
    sulfoisophthalic acid and     bisstearamide                           
    diethylene glycol                                                     
6   92/8 isophthalic acid/5-sodio-                                        
                   70  Adipic 30  Talc   5                                
    sulfoisophthalic acid and                                             
    diethylene glycol                                                     
7   90/10 isophthalic acid/5-(4-                                          
                   50  Cyclohexane                                        
                              50  Stearic                                 
                                         2                                
    sodiosulfophenoxy)isophthalic                                         
                       1,3-dicarbo-                                       
    acid and triethylene glycol                                           
                       xylic acid                                         
8   90/10 isophthalic acid/5-sodio-                                       
                   100 --     --  --     --                               
    sulfoisophthalic acid and                                             
    diethylene glycol                                                     
9   90/10 isophthalic acid/5-sodio-                                       
                   30  Adipic 70  --     --                               
    sulfoisophthalic acid and                                             
    diethylene glycol                                                     
10  90/10 isophthalic acid/5-sodio-                                       
                   80  Adipic 20  --     --                               
    sulfoisophthalic acid and                                             
    diethylene glycol                                                     
11  85/15 isophthalic acid/5-sodio-                                       
                   100 --     --  --     --                               
    sulfoisophthalic acid and                                             
    70/30 diethylene glycol and                                           
    1,4-cyclohexanedimethanol                                             
__________________________________________________________________________
 
    
     EXAMPLE 2 
     Two parts of resin 1 described in Table II are melted at 165° C. under a dry nitrogen atmosphere. One part of C.I. Disperse Red 60 dye containing no dispersing agent or other diluent is slowly added with stirring and allowed to mix until all the dye is fully dissolved. The molten solution is poured out onto a Teflon base and allowed to cool, forming a solid sheet which can be granulated readily. Two grams of this solid solution of dye are dispersed in 120 ml. water at 80° C. A stable dispersion is formed in about 20 minutes and 2.8 g. of high viscosity hydroxyethyl cellulose is dissolved in the mixture to form a thick paste ink suitable for screen printing. When the ink has cooled to room temperature, screen prints are made onto paper sheets and allowed to dry. Heat transfer prints are made by contacting this paper with 100% polyester fabric under 2-6 lb./in 2  pressure for 30 sec. at 210° C. Sharp. clear prints with good dye transfer are obtained. The prints are fast to light, washing, and rubbing. 
     EXAMPLE 3 
     A dye dispersion and transfer print are prepared as in Example 2 except that the pulverized resin and dye are dry mixed together before melting. Results identical to those of Example 2 are obtained. 
     EXAMPLE 4 
     A dye dispersion and transfer print are prepared as in Example 2 except that the dye used is full strength C.I. Disperse Yellow 3. A stable ink results and the transfer print on 100% polyester is fast to light, washing, and rubbing. 
     EXAMPLE 5 
     In the manner described in Example 2, the resins and dyes listed in Table III are mixed to form water-dispersible dye/resin compositions. Aqueous heat transfer printing inks are prepared from each composition, screen printed on transfer paper and transferred to 100% polyester fabric as described in Example 2. The printed colors are fast to light, washing and rubbing. 
     
                       Table III                                                   
______________________________________                                    
Water Dispersible                                                         
Solid Dye/Resin Compositions for Heat Transfer Inks                       
Resin                                                                     
No.*  Parts by Wt.                                                        
                 Disperse Dye     Parts by Wt.                            
______________________________________                                    
8     2          C.I. Disperse Red 60                                     
                                  1                                       
9     2          C.I. Disperse Red 60                                     
                                  1                                       
10    2          C.I. Disperse Red 60                                     
                                  1                                       
3     2          C.I. Disperse Red 60                                     
                                  1                                       
1     2          C.I. Disperse Violet 27                                  
                                  1                                       
3     2          C.I. Disperse Violet 27                                  
                                  1                                       
3     2          C.I. Disperse Red 65                                     
                                  1                                       
______________________________________                                    
 *From Table II                                                           
 
    
     The compositions of this invention also may be prepared as aforesaid by two roll milling as described below, a dry blend of polymer and dye at a temperature above the softening point of the polymer but below the decomposition temperatures of the dye. The dye dissolves or disperses in the polymer during this process and the resulting product appears identical in performance to the product obtained as described earlier herein. 
     EXAMPLE 6 
     Two parts of resin 1 of Table II are blended with 1 part C.I. Disperse Red 60 dye cake. This blend is milled by slowly depositing the dry pulverized materials onto a two roll mill operating at 88° C. front roll temperature, 49° C. back roll temperature, roll surface speed 10.2 meters/min., allowing the material to band, then continuing mixing for about 5 minutes in the usual manner. The dye/resin composition is stripped from the mill, allowed to cool to room temperature and broken into small pieces. Aqueous dye dispersion, ink and transfer print are prepared as in Example 2 with identical results. 
     EXAMPLE 7 
     Two parts of resin 8 of Table II are blended with 1 part C.I. Disperse Red 60 dye cake. This blend is processed as in Example 6 with identical results. 
     The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.