PROCESS FOR PRODUCING ISOBUTYLENE BLOCK COPOLYMER

摘要

An isobutylene block copolymer having stable mechanical properties is provided while inhibiting side reactions even when much time is required for, e.g., liquid transfer after polymerization. The isobutylene block copolymer is produced by a process in which a monomer ingredient comprising isobutylene as the main component and a monomer ingredient in which the main component is not isobutylene are successively added to polymerize them by cationic living polymerization. The process is characterized in that at the time when the conversion of the monomer ingredient added last to the reaction system has reached a desired value, an electron donor compound is added to the reaction system.