PURPOSE: To obtain an N-substituted maleimide/acrylonitrile/styrene copolymer reduced in the residual unreacted N-substituted maleimide content and the methanol-solubles content by controlling the conditions of polymerization.
CONSTITUTION: This copolymer consists of 30-85wt.% aromatic vinyl compound units, 5-30wt.% vinyl cyanide compound units and 10-40wt.% N-substituted maleimide units and has a residual unreacted N-substituted maleimide content of at most 30ppm and a methanol-solubles content of at most 3wt.%. It is produced by continuously feeding a solution consisting of a monomer mixture, a solvent and a polymerization initiator into polymerization equipment having at least two complete mixing reactors connected in series and conducting copolymerization continuously in such a manner that a polymerization temperature of 70-105°C and a conversion of at least 50wt.% are kept in the first reactor while a polymerization temperature of 100-140°C, a conversion of at least 70wt.% and an unreacted N-maleimide concentration of at most 0.1mol% are kept in the final reactor.
MIZUGUCHI TAKAHIRO
TOKUDA YUICHI
MATSUO KIMIHARU
UMEKI KAZUYOSHI
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