Patent ID: 7645511

Claim:
A rubber composition which is comprised of a rubbery polymer, from about 0.5 phr to about 4 phr of a vulcanizing agent, and a core-shell particle which is comprised of (1) a crosslinked elastomeric core consisting essentially of repeat units that are derived from at least one conjugated diolefin monomer and from 15 weight percent to 30 weight percent at least one crosslinking monomer selected from the group consisting of divinyl benzene, diisopropenylbenzene, and 1,2-polybutadiene, based upon the weight of the crosslinked elastomeric core, wherein the crosslinked elastomeric core is a polymeric composition having a glass transition temperature which is within the range of −20° C. to 20° C., and (2) a polymeric shell which is derived from at least one vinyl aromatic monomer, wherein the polymeric shell has a glass transition temperature which is within the range of 50° C. to 160° C., and wherein the weight ratio of the core to the shell is within the range of 20:1 to 7:1.