PURPOSE: To provide a rubber compsn. for tires with reduced hysteresis loss, contg. a block copolymer made from isoprene with butadiene and a block copolymer having a polymer with a metal-carbon bond in the molecular chain.
CONSTITUTION: A rubber compsn. contains 20wt% or more block copolymer comprising polyisoprene blcok (A) obtained by polymn. of isoprene and polybutadiene block (B) obtained by polymn. of butadiene, said block copolymer contg. 10wt% or more each of blocks A and B, and said block copolymer contg. 20% or more polymer with a metal-carbon bond in the molecular chain, and moreover said block copolymer contg. 60% or less vinyl bond. Said block copolymer is blended with natural rubber, polyisoprene rubber, polybutadiene rubber, ethylene/propylene copolymer, styrene/butadiene copolymer, etc.
SAKAKIBARA MITSUHIKO
TSUTSUMI FUMIO
TAKASHIMA AKIO
TOMITA SEISUKE
FUJIMAKI TATSUO
BRIDGESTONE TIRE CO LTD