BRANCHED POLYMER, PROCESS FOR THE PREPARATION THEREOF, TIRE TREAD RUBBER COMPOSITION AND TIRE

摘要

A branched polymer which is a butadiene homopolymer or a copolymer of an aromatic vinyl compound and butadiene and has a glass transition temperature of not less than -50 DEG C. and of which at least 70% by weight of the polymer chains has a branched structure in which high molecules are coupled by a trifunctional or tetrafunctional coupling agent, has an excellent roll processability as required in mixing a rubber component with additives and provides a rubber component for tire tread showing a low rolling resistance and an excellent wet skid resistance characteristic.