PROCESS FOR PREPARING COPOLYMERS

摘要

Process for preparing copolymers The invention relates to emulsion polymerization of an .alpha.-alkylstyrene and an unsaturated nitrile copolymerizable therewith to form a copolymer having good heatresistance. The monomers are reacted in a weight proportion of 70 : 30 to 80 : 20, respectively, in the presence of a radical initiator, and the monomers are introduced into the reaction system in such a manner that the concentration of the unsaturated nitrile remaining unreacted in the reaction system is not less than 31 % by weight of the entire amount of the monomers remaining unreacted in the reaction system at the completion of the introduction of the monomers. The resulting copolymer of the .alpha.-alkylstyrene and the unsaturated nitrile has good thermal resistance and is produced with a marked decrease of the monomers remaining unreacted.