High-performance rubber compsn. for car tyres - contains diene rubber and specific amt. of special styrene-diene rubber of specific molecule weight and defined amts. of styrene and vinyl units

摘要

Rubber compsns.(I) are claimed, based on a rubber consisting of 5-40 wt. % rubber component (R1) with a second rubber (R2). (R1) is a copolymer rubber with Mw 2000-50,000, obtd. by the copolymerisation of a styrene monomer or a deriv. thereof (II) with a diene monomer (III), and (R2) is a diene rubber. (R1) has a micromol. structure which satisfies the follows equations 2A+B =greater than 140 ....(1) 25 = less than A .... (2) 30 = less than B .... (3) where A = styrene content, B = vinyl content. Deriv. (II) is p-methyl-, m-methyl-, p-tert.-butyl-, alpha-methyl- or chloromethyl-styrene, or vinyl-toluene, pref. p-methyl- or alpha-methyl-styrene. (III) is butadiene, isoprene, pentadiene or 2,3-dimethyl-butadiene, pref. butadiene. (R1) is a styrene-butadiene rubber obtd. by soln. polymerisation. (R2) is natural rubber, butadiene rubber, emulsion-polymerised or soln.-polymerised styrene-enriched styrene-butadiene rubber, acrylonitrile-butadiene rubber or chloroprene, pref. an emulsion- or soln.-polymerised styrene-rich styrene-butadiene rubber (SBR). USE/ADVANTAGE - Provides rubber compsn. with excellent performance for car tyre treads, esp. for racing tyres. Compsn. (I) give a remarkable increase in hysteresis loss and loss compliance, thus providing sufficient grip on road surfaces without adverse effects on fracture resistance and elongation etc.; this makes a considerable contribution to safety in high-speed driving.