Japan Synthetic Rubber Co., Ltd.

Tsugio Asakawa

Mitsuo Abe

Shinichi Kimura

Syuji Tsuchikawa

Noriaki Ijuin

Hiroo Nakamura

Teizo Fukuta

Toshihiro Ogawa

Hajime Miyajima

A rubber-modified thermoplastic resin is obtained by polymerizing (b) an aromatic vinyl compound and (c) a vinyl cyanide compound in the presence of (a) a rubbery polymer, and in which the content of the component (a) is 50 to 85% by weight, the content of the component (b) is 5 to 48% by weight and the content of the component (c) is 2 to 45% by weight, and which resin has a Q value of 30.times.10.sup.-4 to 50.times.10.sup.-3 and a grafting degree of 5% by weight or more. A thermoplastic resin composition comprising the above rubber-modified thermoplastic resin and at least one other thermoplastic resin is prepared.

Polymerized aromatic vinyl and vinyl cyanide onto rubber

A thermoplastic resin having an excellent thermal stability and a high heat resistance is prepared by initiating polymerization of 65-85 parts by weight of a monomer mixture (A) consisting of 50-85% by weight of .alpha.-methylstyrene, 3-20% by weight of methyl methacrylate, 2-20% by weight of acrylonitrile, and 0-25% by weight of an aromatic alkenyl compound other than .alpha.-methylstyrene, continuously or intermittently adding, on the way of the polymerization, 2-15 parts by weight of a monomer (B) consisting of acrylonitrile or a mixture thereof with an aromatic alkenyl compound other than .alpha.-methylstyrene to the polymerization system while continuing the polymerization, further adding to the polymerization system 5-25 parts by weight of a monomer (C) consisting of an aromatic alkenyl compound other than .alpha.-methylstyrene, or a mixture thereof with acrylonitrile, and continuing the polymerization to complete the polymerization, the total amount of monomers (A), (B), and (C) being 100 parts by weight. Further, a thermoplastic resin composition having an excellent thermal stability, a high heat resistance and a high impact strength is prepared by mixing the thermoplastic resin thus obtained with a graft copolymer obtained by grafting 60-30 parts by weight of a monomer mixture consisting of 65-80% by weight of an aromatic alkenyl compound and 35-20% by weight of acrylonitrile on 40-70 parts by weight of a diene rubbery polymer in such a proportion that the composition contains 10-30% by weight of the rubbery polymer.

Process for producing .alpha.-methyl styrene-methyl

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Suzuka, Japan

Tsugio Asakawa