Japan Synthetic Rubber Co., Ltd.

Takao Morikawa

Mitsuo Abe

Syuji Tsuchikawa

Akira Kamiya

Masamichi Iwama

Kouzo Kawashima

Teruo Aoyama

A thermoplastic resin composition consisting essentially of (A) 10-90% by weight of a graft copolymer (A) obtained by polymerizing a mixture of an alkenyl cyanide compound and an aromatic alkenyl compound in the presence of a butadiene rubber latex in which 40-100% by weight of butadiene rubber particles (A-1) having an average particle diameter of at least 1,300 .ANG. but less than 2,100 .ANG., 0-60% by weight of butadiene rubber particles (A-2) having an average particle diameter of 2,100 .ANG. or more and 0-20% by weight of butadiene rubber particles (A-3) having an average particle diameter other than the average particle diameters of the particles (A-1) and (A-2) are dispersed, provided that the alkenyl cyanide compound content in the resin component of the graft copolymer (A) is at least 10% by weight but less than 30% by weight, and (B) 90-10% by weight of a copolymer of an alkenyl cyanide compound with an aromatic alkenyl compound having an alkenyl cyanide compound content of 30-40% by weight, the proportion of the butadiene rubber component in the composition being 5-30% by weight. Said thermoplastic resin composition is excellent in surface appearance of molded article, shows an improved ejection whiteining during molding, and a high gloss of molded article.

Thermoplastic resin composition

A process for producing a resin having a high heat resistance with a high polymerization conversion by emulsion-polymerizing .alpha.-methylstyrene (AMS), methyl methacrylate (MMA) and acrylonitrile (AN), characterized in that the polymerization is conducted in two steps; A monomer mixture consisting of 60-85% by weight of AMS, 2-30% by weight of MMA and 5-20% by weight of AN is subjected to copolymerization in the first step until 25-85% by weight, based on the weight of the final copolymer, of a copolymer is formed, and in the second step, at least one monomer of the above three monomers is added to the polymerization system to adjust the composition ratio of the three monomers in the polymerization system so as to fall in the region surrounded by the lines connecting points A, B, C, D and E in the triangular coordinate graph indicating the quantitative relationship of the three monomers, and the resulting monomer mixture is subjected to polymerization conditions to complete the polymerization.

Process for producing thermoplastic resins

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Yokohama, Japan

Takao Morikawa