BLOCK COPOLYMER RESIN AND A PROCESS FOR PRODUCING SAME

摘要

1436812 3-Stage block copolymerization SUMITOMO CHEMICAL CO Ltd 24 Jan 1974 [24 Jan 1973] 03376/74 Heading C3P Block copolymers comprising a central copolymer block of a conjugated diene (B) and an alkenylaromatic compound (A) and terminal blocks of the monomer (A) are obtained by (1) polymerizing monomer A in a hydrocarbon solvent and in the presence of an organo-monolithium compound, (2) adding further monomer A and monomer B and polymerizing in the presence of 0À02 to 2% of a polar organic compound and (3) adding further A and polymerizing therewith. Preferably the overall feed ratio of A : B is 95 : 5 to 60 : 4. The terminal blocks are non-elastomeric, the central block elastomeric. Examples refer to the preparation of styrene-b stryene-co-butadiene-bstyrene or styrene-b-styrene-co-isoprene-b-styrene block copolymers in benzene or cyclohexane using n-butyllithium, with addition of minor amounts of tetrahydrofuran in stage (2).