Mitsubishi Rayon Company, Limited

Masaaki Mohri

Kazuo Kishida

Kiyokazu Kitai

Kohji Matsumoto

Kiyokazu Katai

Disclosed is a thermoplastic resin composition of an enhanced impact strength comprising 100 parts by weight of a thermoplastic resin and 2 to 50 parts by weight of a graft copolymer (A) obtained by emulsion-graft-polymerizing a monomer mixture comprised of a major amount of an acrylic monomer and a minor amount of a monomer selected from aromatic vinyl monomers and vinyl cyanide monomers in the presence of 60 to 90% by weight (as solids), based on the weight of the graft copolymer (A), of a diene type rubber latex containing more than 50% by weight of a diene type rubber polymer having a weight average particle diameter of at least 0.3 .mu.m.

Thermoplastic resin composition

An impact modifier for a thermoplastic resin is disclosed, which comprises (I) 100 parts by weight of a graft copolymer formed by graft-polymerizing (B) a monomer having a vinyl group in the molecule onto (A) a butadiene polymer and, incorporated therein, (II) 0.01 to 5 parts by weight of a thioether type heat stabilizer, (III) 0.01 to 5 parts by weight of a phosphite type heat stabilizer and (IV) 0.01 to 5 parts by weight of a phenol type heat stabilizer having a molecular eight of at least 500. A thermoplastic resin composition having this impact modifier incorporated therein exhibits a good heat discoloration resistance and heat deterioration resistance under high-temperature conditions, as well as an improved impact resistance.

Impact modifier for thermoplastic resin having good heat discoloration

Disclosed is a thermoplastic resin composition comprising (A) a graft copolymer obtained by emulsion-graft-polymerizing 0 to 20% by weight of an acrylic monomer and 0 to 60% by weight of an aromatic vinyl monomer in the presence of 40 to 80% by weight (as solids) of a diene type rubber polymer latex containing at least 50% by weight of a diene type rubber polymer having a weight average particle diameter of at least 0.3 .mu.m, and (B) a copolymer of an .alpha.,.beta.-unsaturated cyclic anhydride and an aromatic vinyl compound. The thermoplastic resin composition has a high heat resistance and impact resistance.

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Hiroshima, Japan

Masaaki Mohri