| 摘要 |
PURPOSE:To provide rubber for tire, which has well-balanced properties between resilience and wet skid resistance, consisting of a straight-chain component and a branched component so as to allow the styrene units in the copolymer chain to be formed by a specified styrene chain distribution. CONSTITUTION:A styrene/butadiene random copolymer is composed of 25-75wt% straight-chain component (A) and 75-25wt% branched component. Component A is a reaction product of a lithium-terminated copolymer (a) with a urea derivative of the formula, obtd. by copolymerizing styrene and butadiene in the presence of an organolithium compd. in a hydrocarbon solvent. Component B is a reaction product of said copolymer (a) with a polyfunctional coupling agent contg. at least three reactive moieties. The random copolymer has a Mooney viscosity (ML1+4, 100 deg.C) of 30-150 and a bonded styrene content of 5-45wt% wherein the styrene unit composed of a single styrene chain is at least 40wt% of the bonded styrene and styrene unit composed of a long chain of at least 8 styrene units is not more than 5wt% of the bonded styrene.
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