tire with tread of special trans - 1,4 - polybutadiene polymer and cis 1,4 - polyisoprene (natural rubber

摘要

This invention relates to a natural rubber-rich rubber composition and tire with a tread thereof. A partial replacement of the natural rubber in the natural rubber-rich tire tread is accomplished by an inclusion of a specialized trans 1,4-styrene/butadiene copolymer rubber characterized by having a combination of bound styrene content and microstructure limitations. The tire tread rubber composition is comprised of a blend of the specialized trans 1,4-styrene/butadiene rubber and cis 1,4-polyisoprene natural rubber optionally together with at least one additional diene-based elastomer in which the natural rubber remains a major portion of the elastomers in the tread rubber composition. The specialized trans 1,4-styrene/butadiene rubber has a bound styrene content in a range of from 15 to 35 percent and a microstructure of its polybutadiene portion composed of from 50 to 80 percent trans 1,4-isomeric units, from 10 to 20 percent cis 1,4- isomeric units and from 2 to 10 percent vinyl 1,2- isomeric units.