PROCESS FOR PREPARING COPOLYMERS OF .ALPHA.-METHYLSTYRENE AND ACRYLONITRILE

摘要

of the Invention Copolymers of alpha-methylstyrene and acrylonitrile having improved composition of uniformity are prepared by emulsion polymerizing a first monomer stream having a weight ratio of alpha-methylstyrene/acrylonitrile from 75/25 to 85/15 until the amount of unreacted alpha-methylstyrene plus acrylonitrile based on total monomer and polymer weight is 20-45 percent and the excess of unreacted alpha-methylstyrene monomer is from 670 to 5000 weight percent based on unreacted acrylonitrile, thereafter polymerizing a second monomer feed stream comprising acrylonitrile until the amount of unreacted alpha-methylstyrene plus acrylonitrile remaining in the reactor is 5-15 percent based on total monomer weight, and continuing the emulsion polymerization until total monomer conversion reaches at least 90 percent. 35,455A-F