Process for producing thermoplastic resin highly resistant to impact and weather
This invention relates to a process for producing a thermoplastic resin excellent in impact, weather and heat resistance and having favorable moldability and high rigidity. 
     As impact resistant molding materials, there are well known thermoplastic resins such as high impact polystyrene and ABS resins. However, these resins are inferior in weather resistance and on exposure to ultraviolet rays deteriorate markedly in mechanical properties accompanied generally by changes in surface appearance, losing in gloss while gaining in discoloration. For this reason, the said thermoplastic resins have been limited to exterior uses only. In order to improve the weather resistance of such butadiene rubber-reinforced thermoplastic resins, the present inventors had previously developed a thermoplastic resin having improved weather and impact resistance, which contains a rubber component derived from an acrylic ester in place of butadiene. However, the thermoplastic resin thus obtained is still inferior to the ABS resin, etc. in impact strength. In order to improve the impact strength to the same level, the rubber content had to be increased, thus resulting in slight decrease in rigidity and hardness. The increase in rubber content also posed a problem on moldability. 
     The object of this invention is to enhance the impact strength without impairing the weather resistance, thereby reducing the rubber content and improving the above-mentioned rigidity and moldability. 
     The present inventors conducted extensive research on the above-mentioned enhancement of impact strength and improvement of rigidity and moldability. As a result, it has been found that a thermoplastic resin composition having a markedly enhanced impact strength and an improved rigidity and moldability can be obtained by a process for graft-copolymerizing [B] 90 to 60 parts by weight of a monomer mixture comprising 30 to 100% by weight of an aromatic vinyl compound such as styrene and 70 to 0% by weight of acrylonitrile plus methyl methacrylate in which the proportion of acrylonitrile is 20 to 100% by weight and that of the latter is 0 to 80% by weight, on [A] 10 to 40 parts by weight (in terms of solids content) of a rubbery copolymer latex obtained by copolymerizing in an aqueous medium 60 to 99.9% by weight of at least one alkyl acrylate in which the alkyl group has, preferably, 1 to 13 carbon atoms, such as butyl acrylate, with 40 to 0.1% preferably 10 to 0.1% by weight of at least one copolymerizable organic polyallyl compound, in the presence of a water-soluble polymer and a radical polymerization initiator in an aqueous medium, which is characterized by subjecting the reaction system prior to the graft-copolymerization to a mechanical mixing and then conducting said graft copolymerization. Thus, this invention has three essential requirements which are (1) obtaining a rubbery copolymer excellent in elasticity and toughness by copolymerizing an acrylic ester with a copolymerizable organic polyallyl compound, (2) graft copolymerizing styrene and/or acrylonitrile and/or methyl methacrylate on said rubbery copolymer latex in the presence of a water-soluble polymer, and (3), prior to said graft-copolymerization, subjecting the reaction system to a mechanical mixing pretreatment. By a synergistic effect of the three requirements, can a thermoplastic resin be obtained having a markedly high impact strength and rigidity, and no satisfactory result would be expected if any one of said three requirements is omitted. 
     The organic polyallyl compounds used in preparing the rubber copolymer act as a crosslinking agent for the acrylic ester, and provide grafting active sites in the graft copolymerization, whereby favorable results are obtained. Such effects result from the fact that the allyl group is very easily reacted with a radical, which enables the effective crosslinking reaction in polymerization into the rubbery copolymer. Further, the remaining allyl groups provide effective grafting active sites in the graft copolymerization, since a radical chain transfer to the residual allyl groups easily takes place. The organic polyallyl compounds used include triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, triallyl trimellitate, diallyl trimellitate, tetraallyl pyromellitate, triallyl pyromellitate, diallyl pyromellitate, diallyl maleate, diallyl fumarate, diallyl adipate, etc., whereas those organic polyallyl compounds which are unable to copolymerize with an acrylic ester, such as triallylamine, diallylamine, and diallyl sulfide are, of course, excluded from the scope of this invention. The amount of the organic polyallyl compound used should be such that 0.1 to 20%, preferably 0.5 to 10%, by weight of the compound based on the total weight of the monomer mixture. When the amount is less than 0.1% by weight, the polyallyl compound cannot show a sufficient crosslinking effect, and when the amount is more than 20% by weight, it adversely affects the rubber elasticity. The organic polyallyl compounds may be used alone or in combination of two or more. 
     The alkyl acrylates used are those which contain an alkyl group having 1 to 13, preferably 4 or less, carbon atoms. 
     In the polymerization into the rubbery copolymer [A], a part of the alkyl acrylate may be replaced by at least one vinyl compound copolymerizable with the acrylic ester, such as, for example, styrene, acrylonitrile, or methyl methacrylate. In such a case, the proportion of the vinyl compound is 30% by weight or less, preferably 20% by weight or less based on the total weight of the monomer mixture. 
     Polymerization initiators which are used in conventional emulsion polymerization may be used in the present polymerization in such an amount as used in a conventional emulsion polymerization. Examples of suitable initiators include redox-type initiators composed of persulfate-sodium sulfite or cumene hydroperoxide-sodium formaldehyde-sulfoxylate. 
     Emulsifiers may be used in such an amount as used in a conventional emulsion polymerization. The emulsifiers used include anionic emulsifiers such as sodium oleate, sodium laurylsulfate, and the like. Nonionic emulsifiers may also be used alone or in combinations with the anionics. 
     Since it is not desired that after the polymerization into the rubbery copolymer [A], there remain unreacted acrylates and polyallyl compounds in large amounts, the polymerization conditions, such as temperature, time and the like should be controlled so that the conversion may be as high as possible. 
     The desired resin is obtained by graft-copolymerizing styrene, acrylonitrile and methyl methacrylate on the aforesaid rubbery copolymer in the presence of a water-soluble polymer after these materials have been subjected to a mechanical mixing. 
     When graft-copolymerization is conducted in the presence of a water-soluble polymer as an adsorption protective layer, the polymerization proceeds in the form of emulsion polymerization at the initial stage, and with the progress of polymerization, the polymer particles formed grow. When the conversion reaches a certain value (70 to 80%), it finally becomes impossible to maintain the emulsion state and inter-particle agglomeration begins to take place to transform the emulsion polymerization into suspension polymerization . At this stage, it is particularly important that the polymerization system has been subjected to a mechanical mixing treatment under suitable conditions prior to the polymerization. Such mechanical pretreatment has the following advantages: Upon mechanically forced contact, the rubbery copolymer [A] is swollen with the monomer mixture [B], whereby a polymer of the mixed monomer is formed inside the rubbery polymer particles and the compatibility of the rubbery copolymer with the resin component (i.e., graft-polymerized component) is enhanced; with monomers during polymerization is facilitated to increase the degree of grafting, resulting in enhancement of compatibility. The term &#34;mechanical mixing&#34; referred to above means mixing by means of conventional stirrers and emulsifying devices such as homogenizer, colloid mill, and the like, and suitable conditions are required in order to obtain optimum results. 
     In general, the protective effect of a water-soluble polymer is, unlike that of a surface active agent, the highest when a single phase is formed, and under conditions other than those for the formation of the single phase, the system becomes rather unstable, and thickening phenomenon results. When polymerization is conducted under such conditions, no desirable result will be obtained because of the excessive growth of particles of the rubbery polymer latex. Thus, the aforesaid suitable mechanical mixing means such mixing conditions as to form a stable single protective phase and its effect may be expressed in terms of phase separation rate (defined hereinafter) and viscosity behavior. For example, the results obtained by use of T. K. Homomixer as an emulsifying equipment were as shown in Table 2, from which it can be seen that a polymer with excellent characteristics is obtained from polymerization in the stable dispersion state at a low phase separation rate and a low viscosity. 
     Depending upon the type of emulsifying equipments, the optimum conditions should be selected for each, but it is clear that they can be settled by means of the phase separation rate and the viscosity behavior. The graft-polymerization temperature is preferably 60° C. or more to sufficiently swell the rubbery copolymer with the monomer mixture.  pg,8 
     The water-soluble polymers for use in graft-polymerization include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, partially hydrolyzed polyvinyl alcohol (polymerization degree, 1,000 to 2,000; saponification degree, 80 to 90%), sodium polyacrylate, and polyacrylic acid. These may be used alone or in combination. The amount of water-soluble polymer used is preferably 0.05 to 5% by weight based on the weight of the monomers though may be varied depending upon the type and amount of emulsifier and the type of water-soluble polymer used. 
     When the graft polymerization is conducted in the presence of the aforesaid water-soluble polymer, a polymer having a high impact strength may be obtained as mentioned above, and, in addition, the after treatment is simplified because of transformation into suspension polymerization which makes such a salting-out step as in emulsion polymerization unnecessary. The suitable monomer mixture for graft polymerization consists of 30 to 100% by weight of an aromatic vinyl monomer such as styrene, α-methylstyrene, α-ethylstyrene, or their nucleus-substituted derivatives, for example, vinyltoluene, chlorostyrene or the like, and 0 to 70% by weight of acrylonitrile plus methyl methacrylate in which the proportion of the former to the latter is 20 to 100:80 to 0 by weight. As the polymerization initiators for graft-copolymerization, there may be used those which are used in synthesizing the aforesaid rubbery copolymer and/or oil-soluble polymerization initiators such as lauroyl peroxide, benzoyl peroxide, azobisisobutyronitrile, and the like, in the same amount as in the production of the rubber copolymer. 
     In order to obtain a suitable degree of polymerization, it is possible to use a chain transfer agent, such as tert-dodecyl mercaptan or the like (ordinarily 1% by weight or less based on the monomers used). 
    
    
     The invention is illustrated below in further detail with reference to Examples, in which all parts are by weight. 
     EXAMPLE 1 
     
         ______________________________________                                    
Recipe                                                                    
Component I                                                               
 Potassium persulfate    0.8      parts                                   
 Sodium sulfite          0.16     &#34;                                       
 Sodium oleate           17.6     &#34;                                       
 Deionized water         1600     &#34;                                       
Component II                                                              
 Butyl acrylate          784      parts                                   
 Triallyl isocyanurate   15.2     &#34;                                       
Component III                                                             
 Partially hydrolyzed polyvinyl alcohol                                   
                         3.6      parts                                   
 having a saponification degree of                                        
 80±1.5% and a degree of                                               
 polymerization of 1,700                                                  
 (KH-17 produced by the Nippon                                            
 Synthetic Chemical Industry Co.)                                         
 Deionized water         850      &#34;                                       
 Rongalite               2.1      &#34;                                       
Component IV                                                              
 Styrene                 450      parts                                   
 Acrylonitrile           150      &#34;                                       
 Lauroyl peroxide        1.8      &#34;                                       
 tert-Dodecyl mercaptan  1.5      &#34;                                       
 Cumene hydroperoxide    2.1      &#34;                                       
Component V                                                               
 Partially hydrolyzed polyvinyl alcohol                                   
                         1.6      parts                                   
 (KH-17)                                                                  
 Deionized water         800      &#34;                                       
______________________________________                                    
 
    
     Polymerization procedure 
     Components I and II, each dissolved uniformly, were charged in a reactor, heated to 60° C. after replacement of the air therein by nitrogen while stirring, and allowed to react for 4 hours. The temperature was further elevated to 80° C. and the reaction was continued for a further 3 hours. After completion of the polymerization, the contents were cooled to obtain a butyl acrylate rubber latex [A]. Components III and IV, each dissolved uniformly, were charged into another reactor and homogenized with stirring. The latex [A] was added to the reactor until the concentration became 18% by weight in terms of solids content and mixing was effected by means of T. K. Homomixer (the voltage applied was regulated to 50 V by means of a transformer &#34;Slidac&#34;) for 30 minutes, after which the temperature was elevated to 70° C. to initiate the polymerization. With progress of polymerization, the viscosity of the mixture increased until stirring became difficult, when Component V was added to ensure smooth stirring and to transform the polymerization into suspension polymerization. Subsequently, the temperature was maintained at 80° C. for 2 hours and at 90° C. for 3 hours to complete the polymerization, after which the mixture was dehydrated and dried to obtain a powder. The powder was milled and extruded into pellets, which were then injection molded at 240° C. under a molding pressure of 90 kg/cm 2 . The injection molded pieces were tested for characteristic properties according to the testing methods specified in JIS (an abbreviation of Japanese Industrial Standards) and ASTM. The rubber latex [A] was added dropwise to a mixture of isopropanol and water (3:1) to be coagulated. The coagulum was washed and dried to obtain a solid matter which was immersed in acetone while stirring for 24 hours to dissolve the soluble matter. The insoluble residue was isolated by means of a high speed centrifuge to determine the insoluble matter content. The insoluble matter was further immersed in butyl acrylate monomer at 20° C. for 24 hours to be swollen, and then weighed to measure the degree of swelling. The dehydrated powder obtained from graft-polymerization was extracted with acetone used as a solvent in a Soxhlet extractor for 24 hours to obtain the insoluble matter. The acrylonitrile content of the insoluble matter was determined. The percentage of graft was calculated from the following equation, taking the charged ratio into account. ##EQU1## 
     Referential Example 1 
     Components III and IV were changed in composition as mentioned hereunder and using these components, emulsion polymerization was carried out. After completion of the polymerization, the resulting polymer was salted out, dehydrated and dried in a conventional manner to obtain a powder. Other procedures were similar to those in Example 1. 
     
         ______________________________________                                    
Component III                                                             
 Partially hydrolyzed polyvinyl                                           
                       0       part                                       
 alcohol (KH-17)                                                          
 Sodium oleate         6.0     parts                                      
 Deionized water       900     &#34;                                          
 Rongalite             2.1     &#34;                                          
Component IV                                                              
 Styrene               450     parts                                      
 Acrylonitrile         150     &#34;                                          
 Lauroyl peroxide      0       part                                       
 tert-Dodecyl mercaptan                                                   
                       1.5     parts                                      
 Cumene hydroperoxide  2.1     &#34;                                          
______________________________________                                    
 
    
     Referential Example 2 
     By using the same mixing ratio as in Example 1, a rubber latex [A] was obtained from Components I and II, and a poly(styrene-acrylonitrile) latex [B] was obtained from Components III and IV. These two latices were blended to obtain a resin composition. Other treatments were carried out in the same manner as in Example 1. The results obtained in Example 1, and Referential Examples 1 and 2 were as shown in Table 1. 
     
                                           Table 1                                 
__________________________________________________________________________
Mechanical property                                                       
               Notched Izod                                               
                      Tensile                                             
                           Tensile       Mold-                            
Polymerization impact value                                               
                      strength                                            
                           modulus                                        
                                Rate of flow                              
                                         ability                          
type           (kg.cm/cm)                                                 
                      (kg/cm.sup.2)                                       
                           (kg/cm.sup.2)                                  
                                (× 10.sup.-3 cm.sup.3 /sec)         
                                         *                                
__________________________________________________________________________
      Emulsion                                                            
      suspension                                                          
Example 1                                                                 
      polymerization                                                      
               28     450  24,000                                         
                                2.5      o                                
      (present process)                                                   
Referential                                                               
      Emulsion 8.0    430  22,000                                         
                                3.0      x                                
Example 1                                                                 
      polymerization                                                      
Referential                                                               
      Latex blend                                                         
               4.5    420  22,000                                         
                                4.5      x                                
Example 2                                                                 
                                Koka type                                 
                                flow tester,                              
Testing        ASTM   JIS  JIS  200° C., 20 kg,                    
                                         --                               
method                                                                    
      --       D 256  K 6361                                              
                           K 6301                                         
                                nozzle                                    
                                1 φ × 2 mm                      
__________________________________________________________________________
 Note:                                                                    
 *x: Delamination and weld line observed                                  
 o : Good                                                                 
 
    
     EXAMPLE 2 
     The same components as in Example 1 were mixed by means of T. K. Homomixer under varied conditions to examine relationships between the phase separation rate as well as the viscosity and the impact strength of the resin obtained (Table 2). The phase separation rate referred to herein was expressed in terms of the percentage of the aqueous phase formed by phase separation after the mixture was allowed to stand for 2 hours. The viscosity was measured by means of a B.L-type rotating viscosimeter using a No. 2 rotor at 60 rpm. Other mixing conditions were similar to those in Example 1. It is seen from Table 2 that the phase separation rate becomes minimum at an intensity of 50 V, and the particles are most stably dispersed. The impact strength also shows the maximum value under such conditions. 
     The viscosity increased in proportion to the intensity of mixing. This is because dispersion is insufficient at low intensities of mixing, while rather agglomeration occurs at too high intensities. The optimum results were obtained at intermediate intensities. 
     
                       Table 2                                                     
______________________________________                                    
     Inten-                                                               
     sity    Duration Rate of                                             
     of      of       phase          Notched Izod                         
     mixing  mixing   separation                                          
                              Viscosity                                   
                                     impact value                         
No.  (V)     (min)    (%)     (cps)  (kg.cm/cm)                           
______________________________________                                    
2-1  30      10       20.0    9.3    9.5                                  
2-2          30       17.5    8.5    8.3                                  
2-3  50      10       5.5     20.0   23                                   
2-4          30       2.5     15.3   28                                   
2-5  70      10       8.5     61.3   18                                   
2-6          30       7.0     68.3   16                                   
2-7  90      10       12.0    134    10                                   
2-8          30       16.0    103    8.5                                  
______________________________________                                    
 
    
     EXAMPLE 3 
     Of the components in Example 1, the type of the organic polyfunctional compounds to be copolymerized with the acrylic ester was varied, and the characteristic properties of the graft copolymers derived therefrom were examined (Table 3). The mixing conditions were otherwise similar to those in Example 1. 
     
                                           Table 3                                 
__________________________________________________________________________
          Physical properties of                                          
                             Per-                                         
                                 Mechanical characteristics               
          rubbery copolymer  cent-                                        
                                 of graft copolymer                       
          Rate of flow       age                                          
          (Koka-type                                                      
                   Degree                                                 
                        Insoluble                                         
                             of  Notched Izod                             
                                          Tensile                         
                                               Tensile                    
          flow tester                                                     
                   of   matter                                            
                             graft                                        
                                 impact value                             
                                          strength                        
                                               modulus                    
          (× 10.sup.-3 cm.sup.3 /sec)                               
                   swelling                                               
                        (%)  (%) (kg.cm/cm)                               
                                          (kg/cm.sup.2)                   
                                               (kg/cm.sup.2)              
__________________________________________________________________________
Triallyl                                                                  
isocyanurate                                                              
          0-0.8    7-9  ˜100                                        
                             10-15                                        
                                 28       450  24,000                     
Divinylbenzene                                                            
          16            Trace                                             
                             0   5.2      310  16,000                     
Dicyclopentadiene                                                         
methacrylate                                                              
          5.0      10-12                                                  
                        75   5   10       390  21,000                     
Ethylene glycol                                                           
dimethacrylate                                                            
          14       15   72   ˜0                                     
                                 4.8      350  17,000                     
Diethylene glycol                                                         
dimethacrylate                                                            
          10       15   70   ˜0                                     
                                 4.6      360  16,000                     
Triethylene glycol                                                        
dimethacrylate                                                            
          13       14   70   ˜0                                     
                                 3.7      340  17,000                     
Tetraethylene                                                             
glycol    11       15   70   ˜0                                     
                                 4.0      350  18,000                     
dimethacrylate                                                            
Tetradecane-                                                              
ethylene glycol                                                           
          10       15   70   ˜0                                     
                                 2.6      360  17,000                     
dimethacrylate                                                            
Triallyl                                                                  
cyanurate 2-3      10   92   5-10                                         
                                 22       410  22,000                     
Diallyl                                                                   
phthalate 4-5      12   85   5   14       400  21,000                     
Diallyl                                                                   
isophthalate                                                              
           4.5     12   83   0-5 12       380  21,000                     
Diallyl                                                                   
terephthalate                                                             
          4.0      11   80   0-5 11       380  20,000                     
Triallyl                                                                  
trimellitate                                                              
          3.5      10-12                                                  
                        85   0-5 14       390  21,000                     
Triallyl                                                                  
pyromellitate                                                             
          4.0      12   80   0-5 12       400  21,000                     
Tetraallyl                                                                
pyromellitate                                                             
          3.8      10-12                                                  
                        80   0-5 12       380  21,000                     
Diallyl maleate                                                           
          4.5      12   82   0-5 13       400  22,000                     
No crosslinking                                                           
agent     30       --    0   0   2.5      280  14,000                     
__________________________________________________________________________
 Note:                                                                    
 1. Rate of flow: Koka type flow tester (plunger type flow tester),10     
 × 2 mm nozzle, 200° C., 20 kg                               
 2. Conditions for synthesis: Rubber content, 18%; St/AN = 3/1; Other     
 conditions were similar to Example 1.                                    
 
    
     EXAMPLE 4 
     The solids content of a butyl acrylate rubber latex [A] prepared in accordance with the recipe in Example 1 was adjusted to 22% (Example 4-1), 15% (Example 4-2), and 12% (Example 4-3), and graft copolymerization was effected using the latex. Other conditions for treatments were similar to those in Example 1. The results obtained are shown in Table 4. 
     
                       Table 4                                                     
______________________________________                                    
Mechanical Characteristics                                                
                                     Rate of                              
Amount     Notched                   flow (Koka                           
of         Izod                      type                                 
rubber     impact    Tensile  Tensile                                     
                                     flow tester)                         
(% by      value     strength modulus                                     
                                     (× 10.sup.-3                   
wt)        (kg.cm/cm)                                                     
                     (kg/cm.sup.2)                                        
                              (kg/cm.sup.2)                               
                                     cm.sup.3 /sec)                       
______________________________________                                    
Ex-                                                                       
ample 22       40        400    21,000 2.0                                
4-1                                                                       
Ex-                                                                       
ample 18       28        450    25,000 2.5                                
Ex-                                                                       
ample 15       16        470    26,000 3.0                                
4-2                                                                       
Ex-                                                                       
ample 12       12        490    29,000 3.0                                
4-3                                                                       
______________________________________                                    
 
    
     EXAMPLE 5 
     Elastomer latices [A] were synthesized in accordance with the recipe in Example 1, except that the amount of triallyl isocyanurate in Component II was changed to 1% by weight (Example 5-1), and 5% by weight (Example 5-2). Components III and IV were graft-copolymerized on the latices [A], the solids content of which were both 18% by weight. Other treatments were similar to those in Example 1. The result obtained are shown in Table 5. 
     
                       Table 5                                                     
______________________________________                                    
         Mechanical Characteristics                                       
Amount                                                                    
of                                                                        
tri-                                                                      
allyl                                Rate of                              
iso-       Notched                   flow (Koka                           
cyanu-     Izod                      type                                 
rate       impact    Tensile  Tensile                                     
                                     flow tester)                         
(% by      value     strength modulus                                     
                                     (× 10.sup.-3                   
wt)        (kg.cm/cm)                                                     
                     (kg/cm.sup.2)                                        
                              (kg/cm.sup.2)                               
                                     cm.sup.3 /sec)                       
______________________________________                                    
Ex-                                                                       
ample 1.0      18        410    21,000 3.0                                
5-1                                                                       
Ex-                                                                       
ample 2.0      28        450    25,000 2.5                                
Ex-                                                                       
ample 5.0      22        470    28,000 3.0                                
5-2                                                                       
______________________________________                                    
 
    
     EXAMPLE 6 
     Component IV in the recipe in Example 1 was replaced by the undermentioned. Other components were the same as in Example 1. 
     
         ______________________________________                                    
Component IV                                                              
            Styrene           38      parts                               
            Acrylonitrile     169     &#34;                                   
            Methyl methacrylate                                           
                              93      &#34;                                   
            Lauroyl peroxide  1.8     &#34;                                   
            tert-Dodecyl mercaptan                                        
                              1.5     &#34;                                   
            Cumene hydroperoxide                                          
                              2.1     &#34;                                   
______________________________________                                    
 
    
     The results obtained are shown in Table 6. 
     
                                           Table 6                                 
__________________________________________________________________________
                     Mechanical characteristics                           
Composition of resin (%)                                                  
                     Notched                                              
                Methyl                                                    
                     Izod            Rate of flow                         
                meth-                                                     
                     impact                                               
                           Tensile                                        
                                Tensile                                   
                                     (Koka type                           
           Acrylo-                                                        
                acry-                                                     
                     value strength                                       
                                modulus                                   
                                     flow tester)                         
Styrene    nitrile                                                        
                late (kg.cm/cm)                                           
                           (kg/cm.sup.2)                                  
                                (kg/cm.sup.2)                             
                                     (× 10.sup.-3                   
__________________________________________________________________________
                                     cm.sup.3 /sec)                       
Example 6                                                                 
      56.4 28.1 15.5 20    450  25,000                                    
                                     3.5                                  
Example 1                                                                 
      75   25   0    28    450  25,000                                    
                                     2.5                                  
__________________________________________________________________________
 
    
     EXAMPLE 7 
     Acrylonitrile was added as a third component to Component II in Example 1 for use in copolymerization. Other conditions were the same as in Example 1. The results obtained are shown in Table 7. 
     
         ______________________________________                                    
Component II                                                              
Example 7-1                                                               
 Butyl acrylate       744     parts                                       
 Acrylonitrile        40      &#34;                                           
 Triallyl isocyanurate                                                    
                      15.2    &#34;                                           
Example 7-2                                                               
 Butyl acrylate       704     parts                                       
 Acrylonitrile        80      &#34;                                           
 Triallyl isocyanurate                                                    
                      15.2    &#34;                                           
Example 7-3                                                               
 Butyl acrylate       664     parts                                       
 Acrylonitrile        120     &#34;                                           
 Triallyl isocyanurate                                                    
                      15.2    &#34;                                           
______________________________________                                    
 
    
     
                                           Table 7                                 
__________________________________________________________________________
       Amount of                                                          
       acrylonitrile                                                      
              Mechanical Characteristics                                  
       in rubber                                                          
              Notched Izod                                                
                     Tensile                                              
                          Rate of flow                                    
                                      Mold-                               
       component                                                          
              impact value                                                
                     strength                                             
                          (Koka type flow tester)                         
                                      ability                             
       (% by wt)                                                          
              (kg.cm/cm)                                                  
                     (kg/cm.sup.2)                                        
                          (× 10.sup.-3 cm.sup.3 /sec)               
                                      *                                   
__________________________________________________________________________
Example 1                                                                 
       0      28     450  2.5         o                                   
Example 7-1                                                               
       5      25     450  2.5         o                                   
Example 7-2                                                               
       10     30     460  2.0         Δ                             
Example 7-3                                                               
       15     33     480  1.0         Δ                             
__________________________________________________________________________
 Note: *Moldability                                                       
 Δ: Delamination; some weld lines                                   
 o : Good (no delamination; no weld line detected.)                       
 
    
     EXAMPLE 8 
     An outdoor exposure test was conducted on test specimens obtained in Example 1 to confirm weather resistance. The test specimens were fixed on a panel facing south and at 45° from horizontal and exposure was continued for a period extending from March to September. The exposed specimens were tested by the Izod impact testing method for unnotched specimens, the impact being applied on the exposed side of the test specimens. The results obtained are shown in Table 8. 
     
                                           Table 8                                 
__________________________________________________________________________
               Unnotched Izod impact value (kg.cm/cm)                     
               after exposure and percentage retention (%)                
        Exposure                                                          
               0      10  20  1   3   6                                   
        days   (initial value)                                            
                      days                                                
                          days                                            
                              month                                       
                                  months                                  
                                      months                              
__________________________________________________________________________
Sample  Impact value                                                      
               150    160 155 150 152 148                                 
(this invention)                                                          
        % Retention                                                       
               --     107 103 100 101 98                                  
ABS*    Impact value                                                      
               114    52  15  18  21  15                                  
        % Retention                                                       
               --     46  13  16  19  13                                  
ABS**   Impact value                                                      
                73    63  13  14  13  13                                  
        % Retention                                                       
               --     86  18  19  18  18                                  
__________________________________________________________________________
 Note:                                                                    
 *MHA MHA resin, Sumitomo Bakelite Co.                                    
 **JSR-35 resin, Japan Synthetic Rubber Co.                               
 
    
     EXAMPLE 9 
     The same procedures as in Example 1 were repeated except that ethyl acrylate and n-octyl acrylate were substituted for the butyl acrylate in Component II to obtain the results shown in Table 9. 
     
                       Table 9                                                     
______________________________________                                    
           Notched Izod                                                   
                      Tensile  Tensile                                    
Kind of    impact value                                                   
                      strength modulus                                    
                                      Mold-                               
acrylate   (kg.cm/cm) (kg/cm.sup.2)                                       
                               (kg/cm.sup.2)                              
                                      ability                             
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Ex-   Ethyl                                                               
ample acrylate 18         420    26,000 o                                 
7     n-Octyl                                                             
      acrylate 20         320    20,000 Δ                           
Ex-   n-Butyl                                                             
ample acrylate 28         450    24,000 o                                 
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