A thermoplastic resin having excellent thermal stability and a high heat resistance is prepared by initiating polymerization of from 65 to 85 parts by weight of a monomer mixture (A) consisting of from 50 to 85% by weight of a-methylstyrene, from 3 to 20% by weight of methyl methacrylate, from 2 to 20% by weight of acrylonitrile and from 0 to 25% by weight of an aromatic alkenyl compound other than a-methylstyrene, continuously or intermittently adding, in the course of the polymerization, from 2 to 15 parts by weight of a monomer (B) consisting of acrylonitrile or a mixture thereof with an aromatic alkenyl compound other than a-methylstyrene to the polymerization system while continuing the polymerization, further adding to the polymerization system from 5 to 25 parts by weight of a monomer (C) consisting of an aromatic alkenyl compound other than a-methylstyrene, or a mixture thereof with acrylonitrile, and completing the polymerization, the total amount of monomers (A), (B) and (C) being 100 parts by weight. Further, a thermoplastic resin composition having excellent thermal stability, a high heat resistance and a high impact strength is prepared by mixing this thermoplastic resin with a graft copolymer obtained by grafting from 60 to 30 parts by weight of a monomer mixture comprising from 65 to 80% by weight of an aromatic alkenyl compound and from 35 to 20% by weight of acrylonitrile on from 40 to 70 parts by weight of a diene rubbery polymer in such a proportion that the composition contains from 10 to 30% by weight of the rubbery polymer.
一种具有优异热稳定性和高耐热性的热塑性
树脂是通过以下方法制备的:将 65 至 85 份(重量)由 50 至 85%(重量)a-
甲基苯乙烯、3 至 20%(重量)
甲基丙烯酸甲酯、2 至 20%(重量)
丙烯腈和 0 至 25%(重量)a-
甲基苯乙烯以外的芳香族烯基化合物组成的单体混合物(A)开始聚合,并在聚合过程中连续或间歇地加入: 2 至 15 份(重量)由
丙烯腈或其与 a-
甲基苯乙烯以外的芳香族烯基化合物组成的单体(B),同时继续聚合体系、在继续聚合的同时,向聚合体系中加入 2 至 15 份(按重量计)由
丙烯腈组成的单体(B)或其与芳香族烯基化合物(a-
甲基苯乙烯除外)的混合物,再向聚合体系中加入 5 至 25 份(按重量计)由芳香族烯基化合物(a-
甲基苯乙烯除外)组成的单体(C)或其与
丙烯腈的混合物,然后完成聚合,单体(A)、(B)和(C)的总量为 100 份(按重量计)。此外,一种热塑性
树脂组合物具有优异的热稳定性、高耐热性和高冲击强度,其制 备方法是将这种热塑性
树脂与一种接枝共聚物混合,接枝共聚物是将 60 至 30 份 (重量)的单体混合物接枝到 40 至 70 份(重量)的二烯橡胶聚合物上,该单体混 合物包括 65 至 80% (重量)的芳香族烯基化合物和 35 至 20% (重量)的
丙烯腈,接枝比例为该组合物含有 10 至 30% (重量)的橡胶聚合物。