Transparent high-impact styrene-butadiene block copolymers comprises at least two hard blocks and a soft block with a low 1,2-vinyl content for improved thermal stability

摘要

New block copolymers (I) comprise at least two vinylaromatic hard blocks (S1 and S2) and at least one interposed statistical diene/vinylaromatic soft block (B/S), where the proportion of hard blocks is more than 40 wt.% and the 1,2-vinyl content of the soft block is less than 20%. Independent claims are also included for the following: (1) polymer mixtures comprising (I) and other styrene polymers; (2) production of (I) by sequential anionic polymerization, where polymerization of at least the soft block is effected in the presence of a potassium salt.