JPS6346781B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention can provide a molded product with highly excellent mechanical properties such as impact resistance and sufficiently low gloss value, so-called excellent erasability, especially when used for vacuum forming of sheets. The present invention relates to a method for producing an impact-resistant thermoplastic composition in which the change in gloss value before and after molding is extremely small. ABS resins are made by graft polymerizing vinyl monomers such as aromatic vinyl monomers, vinyl cyanide monomers, and acrylic acid monomers to rubbery polymers such as synthetic rubber and natural rubber. Rubber-modified impact-resistant thermoplastic resins such as high-impact polystyrene are used in a variety of applications taking advantage of their excellent properties, but recently they have been particularly used in automotive interior applications, where they have not only impact resistance but also smooth and glossy surfaces. It is required to have a smooth and calm feel, so-called fadeability. Further, in these applications, vacuum forming of the sheet is often used, and it is desired that the sheet has characteristics such that there is little change in gloss before and after forming and that it has erasable properties. Therefore, various methods of manufacturing resins with impact resistance and erasability have been studied, for example (1)
A method of blending a solid rubbery polymer and a rigid thermoplastic resin, (2) a method of blending an acrylonitrile-butadiene copolymer latex with a relatively high acrylonitrile content and a rigid thermoplastic resin latex, and (3) a method of blending an ABS resin with an acrylic resin. Methods of blending acid ester-based rubbery polymers (4) Methods of applying surface treatments such as embossing to ABS resin sheets have been proposed. However, in method (1), the rubbery polymer is difficult to disperse sufficiently, which damages the surface of the molded product, making it impossible to obtain a resin with sufficient impact resistance. Although it has excellent erasability, when it is subjected to vacuum forming, the erasability decreases after processing, and it has the disadvantage of generating gloss. In addition, method (3) has the disadvantage that the acrylic ester-based rubbery polymer is not sufficiently dispersed and the surface of the molded product is damaged, while method (4) requires surface treatment of the sheet, resulting in high costs. There is a problem that not only is economic efficiency impaired, but also that the gloss after vacuum forming varies. In addition, a method for improving the dispersion state of rubber particles by melt-kneading a graft copolymer obtained by suspension polymerizing a solution consisting of a rubbery polymer and a vinyl monomer (Japanese Patent Application Laid-Open No. 157195-1989) is also known, but although this method has excellent erasability, it has the disadvantage that satisfactory impact resistance cannot be obtained. In view of this situation, the inventors of the present invention conducted extensive studies with the aim of efficiently producing a resin with an excellent balance between impact resistance and erasability. Graft copolymer (A) obtained by suspension polymerization of a solution consisting of vinyl monomers and graft copolymer (A) obtained by emulsion graft polymerization of vinyl monomers in the presence of a rubbery polymer latex. By melt-kneading a mixture of B) and, if necessary, a vinyl monomer polymer (C) within a temperature range of 150 to 300°C while applying a shear rate of 10 sec ^-1 or more, the above-mentioned purpose can be achieved. The inventors have discovered that it is possible to obtain a resin composition that satisfies the above requirements and does not change its erasability when vacuum forming a sheet, and has thus arrived at the present invention. That is, the present invention provides (1) 5 to 50 parts by weight of an essentially gel-free rubbery polymer to a monomer consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and/or an acrylic monomer. 1 to 90 parts by weight of graft copolymer (A) obtained by suspension polymerization of a solution dissolved in 50 to 95 parts by weight of polymer mixture in the presence of an azo compound initiator, (2) rubbery polymer 20 to 90 parts by weight of a monomer mixture consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and/or an acrylic monomer in the presence of 10 to 80 parts by weight of latex (based on solid content). 1 to 70 parts by weight of a graft copolymer (B) obtained by emulsion graft polymerization and (3) a copolymer consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and/or an acrylic monomer Coalescence (C) A dull, durable product characterized by melt-kneading a mixture of 0 to 95 parts by weight (100 parts by weight in total) within a temperature range of 150 to 300°C while applying a shear rate of 10 sec ^-1 or more. A method for producing an impact thermoplastic resin composition is provided. The vinyl monomers used in the present invention include styrene, α-methylstyrene, vinyltoluene,
- Aromatic vinyl monomers such as ethylstyrene, o-, p-chlorostyrene, acrylonitrile,
Examples include vinyl cyanide monomers such as methacrylonitrile and ethacrylonitrile, acrylic monomers such as acrylic acid, methacrylic acid, ethacrylic acid, and their esters such as methyl, ethyl, propyl, and n-butyl. It will be done. Further, a small amount of a maleimide monomer such as maleimide or N-methylmaleimide may be used. These vinyl monomers are used in the polymerization of graft copolymer (A), graft copolymer (B), and copolymer (C).
Although they can be arbitrarily selected and used, it is particularly preferable that the same monomer components are used for the graft copolymer (A), the graft copolymer (B), and the copolymer (C). The content of the rubbery polymer in the graft copolymer (A) of the present invention is 5 to 50 parts by weight, preferably 10 to 40 parts by weight. Erasability is insufficient, and 50
If the amount is more than 1 part by weight, the surface of the molded product of the final resin composition will be extremely poor due to insufficient dispersion of the rubbery polymer, which is not preferable. The rubbery polymer used in the graft copolymer (A) is a rubbery polymer with a glass transition temperature of -10°C or lower and essentially gel-free, such as polybutadiene rubber, acrylonitrile, etc. - Diene rubbers such as butadiene copolymer rubber (NBR), styrene-butadiene copolymer rubber (SBR), and ethylene-propylene-diene terpolymer rubber (EPDM). Note that when obtaining the graft copolymer (A), these rubbery polymers are dissolved in advance in an aromatic vinyl monomer, a vinyl cyanide monomer, and/or an acrylic monomer. If necessary, an organic solvent may be further added to dilute the solution before use. Preferred organic solvents that can be used in this case include benzene, toluene, ethylbenzene, xylene, acetone, and methyl ethyl ketone. The azo compound initiator used for suspension polymerization of the graft copolymer (A) is 2,2'-azobisisobutyronitrile represented by the following general formula. (R' is -CH ₃ , R is -CH ₃ , -C ₂ H ₅ , n-
C ₃ H ₇ , iso-C ₃ H ₇ , cyclopropyl, isobutyl, tert
-butyl, n-C ₅ H ₁₁ , cyclonexyl, etc.) and 1,1′-
Azobiscyclohexanitrile, 1,1'-azobiscyclohexane carbonate and dibutyl-
Examples include 2,2'-azobisisobutyrate and 4-cyanopentanoic acid, and two or more of these may be used in combination. In addition, a small amount of organic peroxide such as benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, cumene hydroperoxide, lauroyl peroxide, etc. may be used in combination within a range that does not impair the purpose of the present invention. However, if an organic peroxide is used alone, the final resin composition will be a resin with a high gloss value, which is not preferable. The suspension stabilizer used in the suspension polymerization method of the graft copolymer (A) is not particularly limited as long as it is a substance that can stably carry out suspension polymerization. In the present invention, the proportion of the graft copolymer (A) in the total composition is preferably 1 to 95 parts by weight, particularly 10 to 80 parts by weight, and if the graft copolymer (A) is 1 part by weight or less, the final resin composition It is not preferable to use more than 95 parts by weight, since the discoloration properties of the product are insufficient, and the impact resistance of the final resin composition decreases. The amount of rubbery polymer latex used in the graft copolymer (B) of the present invention is 10 to 80 parts by weight (in terms of solid content), preferably 20 to 70 parts by weight, and the rubbery polymer is 10 parts by weight or less. If it is more than 80 parts by weight, the rubbery polymer will be poorly dispersed and the appearance of the molded product of the final resin composition will be impaired, which is not preferable. The rubbery polymer latex used in the graft copolymer (B) is mainly a latex containing polybutadiene and a copolymer of butadiene containing 50% by weight or more of butadiene and other copolymerizable monomers. Monomers that can be used for copolymerization with butadiene include aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyltoluene; cyanated vinyl monomers such as acrylonitrile and methacrylonitrile; Acid, methacrylic acid and its methyl, ethyl, propyl, n
- Examples include acrylic monomers such as butyl. In addition to these, rubbery polymers such as polyisoprene, polychloroprene, and terpolymer of ethylene-propylene-diene monomers can also be used. There is no limit to the rubber particle size in these rubbery polymer latexes, but in particular the average particle size is 0.2~
4.0μ is preferred. Furthermore, the gel content and gel swelling degree can be used without any particular restrictions. The vinyl monomers used in the graft copolymer (B) include those similar to the vinyl monomer mixture described above, and this mixture may be added all at once, in portions, or continuously. As the initiator used in the emulsion polymerization of the graft copolymer (B), oxidation-reduction (redox) systems such as organic hydroperoxide-iron salts, and persulfates such as potassium persulfate and ammonium persulfate can be used. . Further, if necessary, polymerization regulators such as mercaptans and terpenes can be used. Emulsifiers used in the emulsion graft polymerization method for graft copolymer (B) include alkali metal salts of fatty acids, alkali metal salts of fatty acid sulfate esters,
Any emulsifier that is commonly used in emulsion polymerization of vinyl monomers such as alkali metal salts of disproportionated rosin acids can be used without any particular limitations. The emulsion graft copolymer (B) is used by coagulating, separating, washing and drying the latex after emulsion polymerization by conventional methods. In the present invention, the proportion of the graft copolymer (B) in the total composition is preferably 1 to 70 parts by weight, particularly 10 to 50 parts by weight, and if the graft copolymer (B) is 1 part by weight or less, the final resin composition If it exceeds 70 parts by weight, the final resin composition will have poor erasing properties, which is not preferable. The copolymer (C) of the present invention is a polymer obtained by copolymerizing the above-mentioned vinyl monomer mixture by a general polymerization method such as an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, or the like. This copolymer (C) may be added to 0% as necessary so that the total amount of the rubbery polymers of graft copolymers (A) and (B) is 5 to 40% by weight in the final resin composition.
~95 parts by weight. Note that if the total amount of the rubbery polymer in the entire composition is less than 5% by weight, satisfactory impact resistance cannot be obtained, and if it is more than 40% by weight, the tensile strength is undesirably reduced. In the present invention, a composition in which the graft copolymer (A), the graft copolymer (B), and the copolymer (C) are premixed in a total of 100 parts by weight is prepared using a single-screw or twin-screw extruder, It is necessary to sufficiently disperse the rubbery polymer in the matrix resin by melt-kneading it in a Banbury mixer, roll, kneader, etc. The kneading temperature during melt-kneading is 150 to 300°C, preferably 200 to 250°C; below 150°C, the rubbery polymer of the graft copolymer (A) will become too small and the final resin composition will be smudged. This is not preferable because it not only deteriorates performance but also extremely reduces productivity.
Further, at temperatures above 300°C, the rubbery polymer of the graft copolymer (A) becomes poorly dispersed, which impairs the appearance of the molded product of the final resin composition, which is not preferable. The shear rate during melt-kneading must be 10 sec ^-1 or higher, and 10 sec ^-1
Melt kneading is performed while applying a shear rate of the above. When the applied shear rate is less than 10 sec ^-1 , the graft copolymer (A)
The rubbery polymer is not sufficiently dispersed in the matrix resin, causing frequent fissures and resulting in a poor surface of the molded product of the final resin composition, which is undesirable. In the present invention, during melt-kneading, commonly used processing aids such as stabilizers and plasticizers, colorants, flame retardants, etc. may be added for use. The final resin composition can be subjected to injection molding, extrusion molding, or other molding applications. The resin composition obtained by the method of the present invention is a graft copolymer in which a network structure containing a monomeric resin is formed with a rubbery polymer film by a suspension polymerization method.
Graft copolymer (B) obtained by emulsion graft polymerization with (A)
By mechanically processing a mixture of copolymers of vinyl monomers and vinyl monomers, the rubbery polymers are uniformly dispersed in the matrix resin, forming spherical and irregularly shaped rubber structures, resulting in impact-resistant It is possible to provide a molded product with excellent balance between properties and erasability. The resin composition obtained by the method of the present invention is particularly effective in sheet molded products. For example, when used for interior parts of automobiles and the like, it has excellent impact resistance and erasability of molded products, so its industrial value is extremely high. Hereinafter, the method of the present invention will be explained in detail with reference to Examples. In addition, the Izod impact strength in the examples is
ASTM D-256-56, tensile strength is ASTM D-
638-61T. Gloss was measured using a Murakami glossmeter device. In addition, parts and % in the examples indicate parts by weight and % by weight, respectively. Example 1 <Production of graft copolymer (A)> 20 parts of linear polybutadiene rubber (Diene NF-35A manufactured by Asahi Kasei Corporation) was dissolved in a mixture of 58 parts of styrene and 22 parts of acrylonitrile in an autoclave,
This monomer mixture contains tert-dodecyl mercaptan.
0.3 parts of azobisisobutyronitrile and 0.5 parts of azobisisobutyronitrile were dissolved and mixed uniformly. Next, after adding an aqueous solution of 0.1 part of methyl methacrylate/acrylamide = 20/80 copolymer and 0.1 part of monosodium phosphate dissolved in 200 parts of pure water,
The gas phase was replaced with _N2 gas and with vigorous stirring
The temperature was raised to 70°C. Polymerization was carried out at 70°C for 4 hours and then at 110°C for 1 hour to complete the graft polymerization and obtain a graft copolymer (A-1). The conversion rate after completion of polymerization was 99%. The obtained bead-shaped graft copolymer (A-1) was washed with water, dehydrated, and dried. <Production of graft copolymer (B)> In an autoclave, add 60 parts of polybutadiene latex (manufactured by Toray Industries, Inc., particle size 0.36μ gel content 90%) (solid content equivalent), 0.3 parts of potassium persulfate, and 100 parts of pure water.
After charging a portion, the gas phase was replaced with N ₂ and the temperature was raised to 70° C. with stirring. When the internal temperature reaches 70℃, add 28 parts of styrene, 12 parts of acrylonitrile and tert-
A mixture of 0.1 part of dodecyl methylcaptan was added continuously over 3 hours. After continuing the reaction for an additional 1 hour, the graft polymerization was completed. The conversion rate was 98%. The obtained graft polymer latex was coagulated with magnesium sulfate, washed with water, dehydrated, and dried to obtain a graft copolymer (B-1). <Production of copolymer (C)> Add an aqueous solution of 0.06 part of methyl methacrylate/acrylamide = 20/80 copolymer and 0.05 part of monosodium phosphate dissolved in 150 parts of pure water to an autoclave, and then stir. 72 parts of styrene, 28 parts of acrylonitrile, tert-dodecyl mercaptan
A mixture of 0.4 parts of azobisisobutyronitrile and 0.4 parts of azobisisobutyronitrile was added. The gas phase was replaced with N ₂ and the temperature was raised to 70° C. with further vigorous stirring. 3 hours at 70℃
Polymerization was further carried out at 110°C for 1 hour. The conversion rate after completion of polymerization was 99%. The obtained bead-like copolymer (C) was washed with water, dehydrated, and dried. <Production of resin composition> 70 parts of graft copolymer (A), graft copolymer (B)
220 parts of a mixture consisting of 10 parts and 20 parts of copolymer (C)
The mixture was fed into an extruder equipped with a devolatilization device set at 100° C., melt-kneaded at a shear rate of 170 sec ^-1 , extruded into guts, and cut to obtain a pellet-like composition.
Test pieces were prepared from the obtained composition by injection molding, and the various physical properties were evaluated. Table 1 shows the results. Furthermore, the erasability was evaluated by creating a 2 m/m sheet by extrusion molding and measuring the gloss of this sheet before and after vacuum molding. Example 2 <Production of graft copolymer (A)> Linear polybutadiene (diene
Dissolve 30 parts of NF-35A) in 53 parts of styrene, 17 parts of acrylonitrile, and 10 parts of ethylbenzene, and uniformly dissolve 0.3 parts of tert-dodecyl mercaptan, 0.3 parts of azobisisobutyronitrile, and 0.1 parts of benzoyl peroxide in this monomer solution. did. Thereafter, suspension polymerization was carried out under the same conditions as in Example 1 to obtain a graft copolymer (A-2). The conversion rate after the completion of polymerization was 96%. <Production of graft copolymer (B)> In an autoclave, add 30 parts (solid content equivalent) of polybutadiene latex (manufactured by Toray Industries, Inc., particle size 0.36 μ, gel content 90%) and 0.5 parts potassium persulfate sodium pyrophosphate. After adding 0.5 parts and 130 parts of pure water,
The gas phase was replaced with N ₂ and the temperature was raised to 70° C. with stirring.
When the internal temperature reached 70°C, a mixed solution of 52 parts of styrene, 18 parts of acrylonitrile, and 0.3 parts of tert-dodecylmercaptan was continuously added over 5 hours.
After continuing the polymerization for an additional hour, the polymerization was terminated. The conversion rate was 97%. The obtained graft copolymer latex was coagulated with magnesium sulfate, washed with water, dehydrated, and dried to obtain a graft copolymer (B-2). <Production of resin composition> 27 parts of graft copolymer (A-2), 40 parts of graft copolymer (B-2), and the copolymer of Example 1
(C) A mixture consisting of 33 parts was fed to an extruder equipped with a devolatilization device set at 200°C, and the shear rate
The mixture was melt-kneaded at 280 sec ^-1 , extruded into guts, and cut to obtain a pellet-like composition. The physical properties of test pieces from these pellets were evaluated in accordance with Example 1, and the results are also shown in Table 1. Example 3 <Production of resin composition> 220 parts of a mixture consisting of 90 parts of graft copolymer (A-1) and 10 parts of graft copolymer (B-2)
The mixture was fed into an extruder equipped with a devolatilization device set at ℃ and melt-kneaded at a shear rate of 310 sec ^-1 to form pellets. The physical properties of test pieces from this pellet were evaluated in Example 1.
The results are also shown in Table 1. Example 4 <Production of resin composition> 10 parts of graft copolymer (A-1), 13 parts of graft copolymer (B-1), and the copolymer of Example 1
(C) A mixture consisting of 77 parts was fed to an extruder equipped with a devolatilization device set at 190°C, and the shear rate
The mixture was melted and kneaded at 150 sec ^-1 to form pellets. Table 1 shows the evaluation results of physical properties. Comparative Example 1 <Production of graft copolymer (A)> The composition of Example 1 was changed to linear polybutadiene (diene
A graft copolymer (A-3) was obtained by operating under exactly the same conditions except that 3 parts of NF-35A), 68 parts of styrene, and 29 parts of acrylonitrile were used. The conversion rate was 98%. <Production of resin composition> A mixture consisting of 90 parts of graft copolymer (A-3) and 10 parts of graft copolymer (B-1) was melt-kneaded under the same conditions as in Example 1 and pelletized.
Table 1 shows the evaluation results of physical properties. Comparative Example 2 <Production of graft copolymer (A)> Linear polybutadiene (diene
Dissolve 55 parts of NF-35A) in 35 parts of styrene, 20 parts of acrylonitrile and 30 parts of ethylbenzene, then add 0.3 parts of azobisisobutyronitrile to this solution.
part was uniformly dissolved. Thereafter, the operation was carried out under the same conditions as in Example 1 to obtain a graft copolymer (A-4).
The conversion rate was 92%. Note that ethylbenzene in the graft copolymer was removed by steam distillation after suspension polymerization. <Production of resin composition> 30 parts of graft copolymer (A-4), 12 parts of graft copolymer (B-2), and the copolymer of Example 1
58 parts of (C) were melt-kneaded under the same conditions as in Example 1 and pelletized. The physical properties are shown in Table 1. Comparative Example 3 <Production of graft copolymer (A)> The initiator of Example 1 was replaced with benzoyl peroxide.
A graft copolymer (A-5) was obtained under exactly the same conditions except that the polymerization temperature was changed to 80° C. for 4 hours. The conversion rate was 98%. <Production of resin composition> Melt-kneading was carried out under the same conditions as in Example 1 except that the graft copolymer (A-1) was changed to the graft copolymer (A-5), and pelletized. The physical properties are shown in Table 1. Comparative Example 4 Graft copolymer (A-1) was supplied to an extruder equipped with a devolatilization device set at 200°C, and melt-kneaded at a shear rate of 180 sec ^-1 to form pellets. The physical properties are shown in Table 1. Comparative Example 5 A mixture of 33 parts of the graft copolymer (B-1) and 67 parts of the copolymer (C) of Example 1 was melt-kneaded under the same conditions as in Example 1 and pelletized. The physical properties are shown in Table 1. Comparative Example 6 <Manufacture of graft copolymer (B)> In an autoclave, 5 parts (solid content equivalent) of polybutadiene latex (manufactured by Toray Industries, Inc., particle size 0.36μ), 0.5 part of potassium persulfate, 0.5 part of sodium pyrophosphate, and pure After adding 150 parts of water, the gas phase was replaced with N ₂ and the temperature was raised to 70° C. with stirring. When the internal temperature reaches 70℃, add 67 parts of styrene and 28 parts of acrylonitrile.
-A mixed solution of 0.5 parts of dodecyl mercaptan was continuously added over 7 hours, and the polymerization was continued for an additional hour, after which the polymerization was completed. The conversion rate was 98%. The obtained graft copolymer latex was coagulated with magnesium sulfate, washed with water, dehydrated, and dried to obtain a graft copolymer (B-3). <Production of resin composition> A mixture of 80 parts of graft copolymer (A-1) and 20 parts of graft copolymer (B-3) was melt-kneaded under the same conditions as in Example 1 and pelletized. Table 1 shows the physical properties.
Shown below. Comparative Example 7 <Manufacture of graft copolymer (B)> 90 parts (solid content equivalent) of polybutadiene latex (manufactured by Toray Industries, Inc., particle size 0.36 μ), 0.2 parts of potassium persulfate, and 70 parts of pure water were added to an autoclave. After replacing the gas phase with _N2 , the temperature was raised to 70°C with stirring.
When the internal temperature reached 70°C, a mixed solution of 7 parts of styrene and 3 parts of acrylonitrile was continuously added over 45 minutes, and the polymerization was continued for an additional hour, after which the polymerization was terminated. The conversion rate was 93%. The obtained graft copolymer latex was coagulated with magnesium sulfate, washed with water, dehydrated, and dried to form a graft copolymer (B-
4) was obtained. <Production of resin composition> 70 parts of graft copolymer (A-1), 10 parts of graft copolymer (B-4), and the copolymer of Example 1
20 parts of the mixture (C) was melt-kneaded under the same conditions as in Example 1 and pelletized. The physical properties are shown in Table 1. Comparative Example 8 The same formulation as in Example-1 was fed to an extruder equipped with a devolatilization device set at 140°C, and the shear rate was
The mixture was melted and kneaded at 25 sec ^-1 to form pellets. The physical properties are shown in Table 1. Comparative Example 9 The same formulation as in Example 1 was supplied to an extruder equipped with a devolatilization device set at 370°C, and melt-kneaded at a shear rate of 95 sec ^-1 to form pellets. The physical properties are shown in Table 1. Comparative Example 10 The same formulation as in Example-1 was supplied to an extruder equipped with a devolatilization device set at 200°C, and melt-kneaded at a shear rate of 6 sec ^-1 to form pellets. The physical properties are shown in Table 1.

[Table] As is clear from the results in Table 1, the resin compositions (Examples 1 to 4) obtained by the method of the present invention have extremely high impact resistance, and have very good erasability on the surface of vacuum-formed products. Excellent. On the other hand, when the amount of rubbery polymer in the graft copolymer (A) is 5 parts by weight or less (Comparative Example 1), only a resin with a high gloss value can be obtained. Moreover, when the rubbery polymer of the graft copolymer (A) is 50 parts by weight or more (Comparative Example 2), the molded product has frequent fissures, which impairs the appearance. When an organic peroxide is used as a polymerization initiator for the graft copolymer (A) (Comparative Example 3), the impact resistance is excellent, but the erasability is insufficient. When only the graft copolymer (A) is used (Comparative Example 4), the erasability is excellent, but the impact resistance is extremely poor, which is not preferable. Further, when only the graft copolymer (B) is used (Comparative Example 5), although the physical properties are excellent, the erasability is insufficient. When the amount of rubbery polymer in the graft copolymer (B) is 10 parts by weight or less (Comparative Example 6), impact resistance is not improved. In addition, the rubbery polymer of graft copolymer (B) is 80%
If the amount is more than 1 part by weight (Comparative Example 7), the appearance of the molded product will be impaired due to the formation of fissures. On the other hand, when the melt-kneading temperature is 150°C or lower (Comparative Example 8), the rubbery polymer of the graft copolymer (A) becomes too small, and not only is sufficient impact strength not obtained, but the erasability is also poor. becomes. Furthermore, when the melt-kneading temperature is 350°C or higher (Comparative Example 9) and the shear rate is 10 sec ^{-1 or} lower (Comparative Example 10), the rubbery polymer of the graft copolymer (A) becomes poorly dispersed.
This is undesirable because it causes frequent formation of fissures on the sheet and impairs the appearance of the molded product.

Claims (1)

[Claims] 1 Rubbery polymer essentially free of gel 5 to 50
A solution prepared by dissolving 50 to 95 parts by weight of a monomer mixture consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and/or an acrylic monomer in the presence of an azo compound initiator In the presence of 1 to 95 parts by weight of the graft copolymer (A) obtained by suspension polymerization as described above and 10 to 80 parts by weight (in terms of solid content) of the rubbery polymer latex, aromatic vinyl monomers and Graft copolymer (B) 1 obtained by emulsion graft polymerization of 20 to 90 parts by weight of a monomer mixture consisting of a vinyl cyanide monomer and/or an acrylic monomer
~70 parts by weight and 3 A mixture of 0 to 95 parts by weight of a copolymer (C) consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and/or an acrylic monomer (100 parts by weight in total) A method for producing a matte, impact-resistant thermoplastic resin composition, comprising melt-kneading the composition at a temperature of 150 to 300°C while applying a shear rate of 10 sec ^-1 or more.