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AssigneeThe Goodyear Tire & Rubber Company
InventorsWen-Liang Hsu, Adel F. Halasa, Barry A. Matrana, Scott M. Christian, Laurie E. Austin, Bill B. Gross
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The subject invention discloses a process for preparing a coupled styrene-isoprene-butadiene rubber which is particularly valuable for use in making automobile tire tread rubber compounds which comprises the steps of (1) solution terpolymerizing in an organic solvent from about 5 weight percent to about 40 weight percent styrene, from about 1 weight percent to about 10 weight percent isoprene, and from about 50 weight percent to about 94 weight percent 1,3-butadiene, based on total monomers, to a conversion of at least about 90% to produce a living styrene-isoprene-butadiene polymer, wherein the terpolymerization is initiated with an organolithium compound, and wherein the terpolymerization is conducted in the presence of a polar modifier at a molar ratio of the polar modifier to the organolithium compound, which is within the range of about 0.5:1 to about 5:1, and wherein the terpolymerization is conducted at a temperature which is within the range of about 20.degree. C. to about 150.degree. C.; and (2) coupling the living styrene-isoprene-butadiene polymer with a coupling agent selected from the group consisting of tin tetrachloride and silicon tetrachloride, wherein the molar ratio of the coupling agent to the organolithium compound is within the range of about 1:3 to 1:6.
A sulfur curable rubber composition which is particularly useful for making tire treads, said rubber composition being comprised of (a) a styrene-isoprene-butadiene rubber which is particularly valuable for use in making tire treads, said rubber being comprised of repeat units which are derived from about 5 weight percent to about 40 weight percent styrene, from about 1 weight percent to about 10 weight percent isoprene, and from about 50 weight percent to about 94 weight percent 1,3-butadiene, wherein the repeat units derived from styrene, isoprene, and 1,3-butadiene are in essentially random order, wherein the rubber has a glass transition temperature which is within the range of about -18.degree. C. to about -48.degree. C., and wherein over 90% of the repeat units in the SIBR which are derived from styrene are in blocks of containing less than three repeat units, wherein the rubber is coupled with a member selected from the group consisting of tin tetrachloride and silicon tetrachloride, wherein the rubber has a Mooney viscosity which is within the range of about 70 to about 120, and wherein the rubber has a number average molecular weight which is within the range of about 250,000 to about 400,000, (b) sulfur, (c) carbon black, (d) a silica filler, (e) an accelerator and (f) at least one additional sulfur curable rubber.
Dependencies are inferred from the claim text.