Process for the preparation of maleimide copolymers and thermoplastic resin composition using the same

摘要

The present invention provides a process for the preparation of maleimide copolymers by emulsion polymerization of an aromatic vinyl monomer, a vinyl cyanide monomer and a maleimide monomer in specific proportions wherein the polymerization is carried out by charging not less than a specific proportion of the aromatic vinyl monomer and optionally not more than a specific proportion of the vinyl cyanide monomer into the polymerization system before initiation of the polymerization; adding, continuously or dividedly, a mixture composed of the total amount of the maleimide monomer and the remainder of the other monomers to the polymerization system after initiation of the polymerization; maintaining the pH of the aqueous phase of the polymerization system in the range of 3 to 9 at the initiation of said polymerization; and using a redox catalyst containing an oil-soluble organic peroxide. According to this polymerization process, maleimide copolymers having excellent thermal resistance and resistance to thermal decomposition can be prepared in high yield. The present invention also provides a resin composition having excellent thermal resistance, resistance to thermal decomposition, and impact resistance which is formed by blending, in a specific proportion, a maleimide copolymer prepared by the aforesaid process with a rubber-reinforced resin obtained by grafting a vinyl cyanide monomer or the like onto a specific elastomer; and optionally blending the resulting thermoplastic resin composition with a thermoplastic resin that is hard at room temperature.