High performance tire tread rubber composition

摘要

This invention relates to a tire tread compound that can be used in manufacturing tires having outstanding traction characteristics without compromising treadwear and rolling resistance. The tire tread compounds of this invention are made utilizing an isoprene-butadiene rubber having a high glass transition temperature and having SnR3 end groups, wherein R represents an alkyl group, such as a tertiary-butyl group. These isoprene-butadiene rubbers are made by reacting an isoprene-butadiene rubber having a glass transition temperature which is within the range of about -50 DEG C. to about 0 DEG C. with a tin compound of the formula SnR3X, wherein R represents an alkyl group and wherein X represents a halogen. This invention more specifically discloses a tire tread rubber composition which is comprised of (1) about 60 phr to about 95 phr of an isoprene-butadiene rubber having a glass transition temperature which is within the range of about -50 DEG C. to about 0 DEG C. and having -SnR3 end groups, (2) about 5 phr to about 30 phr of natural rubber and (3) up to about 25 phr of a rubbery polymer having a low glass transition temperature which is within the range of about -85 DEG C. to about -55 DEG C., with the proviso that the total amount of the natural rubber and the rubbery polymer having a low glass transition temperature does not exceed about 40 phr. The rubbery polymer having a low glass transition temperature will typically be high cis-1,4-polybutadiene, isoprene-butadiene rubber, styrene-butadiene rubber or styrene-isoprene-butadiene rubber.