Process for producing -methyl styrene-methyl methacrylate- acrylonitrile thermoplastic resin

摘要

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 -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 -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 - 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.