BLOCK COPOLYMER AND COMPOSITION THEREOF

摘要

A block copolymer which comprises at least two polymer blocks (S) comprising units derived from a vinylaromatic hydrocarbon monomer and a polymer block (B) comprising isoprene monomer units and 1,3-butadiene monomer units, characterized in that the content of the vinylaromatic hydrocarbon monomer units is 60 to 95 wt.%, the total content of the isoprene monomer units and the 1,3-butadiene monomer units is 40 to 5 wt.%, the weight ratio of the amount of the isoprene monomer units to that of the 1,3-butadiene monomer units is from 45/55 to 97/3, and the amount of the vinylaromatic hydrocarbon monomer units contained in at least one short segment consisting of one to three vinylaromatic hydrocarbon monomer units is 0 to 30 wt.% based on the total amount of the vinylaromatic hydrocarbon monomer units contained in the copolymer.