Patent ID: 7064171

Claim:
A non-random rubbery polymer having characteristics which are particularly beneficial for utilization for manufacturing tire tread compounds, said non-random rubbery polymers being comprised of polymer chains that are derived from a vinyl aromatic monomer and a conjugated diolefin monomer, wherein from about 10 weight percent to about 40 weight percent of the repeat units in the rubbery polymer are derived from the vinyl aromatic monomer, wherein from about 60 weight percent to about 90 weight percent of the repeat units in the rubbery polymer are derived from the conjugated diolefin monomer wherein from about 30 weight percent to about 50 weight percent of the vinyl aromatic repeat units are in sequences containing 5 to 20 vinyl aromatic monomer repeat units, wherein the bound vinyl aromatic monomer content found in the first half of the polymer chains differs from the bound vinyl aromatic monomer content found in the second half of the polymer chains by at least 5 weight percent, wherein the rubbery polymer has a 1,2-vinyl content which is within the range of about 8 percent to about 20 percent, wherein the rubbery polymer has a number average molecular weight which is within the range of 100,000 to 475,000, and wherein the rubbery polymer has a glass transition temperature which is within the range of −82° C. to −50° C.