Dissimilar arm asymmetric radial or star block copolymers for adhesives and sealants

摘要

A radial or star asymmetric block copolymer of the formula (I) is new. (A-HD)x-Y-(UD)z (I). A = vinyl aromatic hydrocarbon block having a peak Mw of 4000-20000; HD = hydrogenated conjugated diene block having a peak Mw of 10000-100000; Y = multifunctional coupling agent; UD = unhydrogenated conjugated diene block having a peak Mw of 1000-80000; x = 2-20; z = 1-10; and x+z = 3-30. The block copolymer has a vinyl aromatic hydrocarbon content of 4-35 wt.%. Also claimed are (i) an adhesive or sealant compsn. comprising the copolymer and a tackifying resin; and (ii) compsns. which are crosslinked.