BLOCK COPOLYMER COMPOSITION, PROCESS FOR PRODUCING THE SAME, AND PRESSURE-SENSITIVE ADHESIVE COMPOSITION

摘要

A composition which comprises as a major component a radial poly(aromatic vinyl)/polyisoprene block copolymer and is usable as a better pressure-sensitive adhesive ingredient. The composition is obtained by reacting a diblock polymer with a coupling agent having a functionality of 4 or higher in the presence of a coupling accelerator. It comprises (a) 1 to 34 wt.% diblock polymer, (b) 34 to 99 wt.% four-branch polymer, and (c) 0 to 50 wt.% two-branch polymer and/or three-branch polymer. In the composition, the poly(aromatic vinyl)/polyisoprene block copolymer has a weight-average molecular weight (Mw) of 260,000 to 500,000. The content of the poly(aromatic vinyl) block in the copolymer is 5 to 24 wt.%.