AROMATIC VINYL/ISOPRENE BLOCK COPOLYMER, PROCESS FOR THE PRODUCTION THEREOF, AND HARDENABLE PRESSURE-SENSITIVE ADHESIVE COMPOSITION CONTAINING THE SAME

摘要

An aromatic vinyl/isoprene block copolymer comprising 5 to 50 wt. % of a branch component represented by the general formula: (A-B)nX (wherein A is an aromatic vinyl polymer block; B is an isoprene polymer block; and X is a residue of a polyfunctional coupling agent) and 50 to 95 wt. % of a diblock component represented by the general formula: A-B (wherein A and B are each as defined above). This copolymer can be prepared by polymerizing an aromatic vinyl monomer in the presence of an organolithium polymerization initiator to form a polymer block A, adding isoprene to the reaction mixture to form an A-B block copolymer, and adding a polyfunctional coupling agent to the reaction mixture to convert part of the A-B block copolymer into the above branch component. The aromatic vinyl/isoprene block copolymer is useful as a hardenable pressure-sensitive adhesive.