Patent ID: 8584725
Filing Date: 2013-11-19
Classification: B60C,Y10T

Abstract:
1. A method of preparing a rubber composition comprises: (A) mixing of rubber composition containing a sulfur curable elastomer at an elevated temperature in a range of from about 140° C. to about 180° C., and sufficient to create free radicals on the elastomer chain, in an at least one sequential preparatory rubber mixing stage in the absence of sulfur and sulfur curatives; (B) mixing sulfur curatives with the rubber composition in a subsequent productive rubber mixing stage to a temperature in a range of from about 90° C. to about 115° C.; wherein the rubber composition is cooled to a temperature below about 40° C. after each of said mixing stages; wherein a controlled free radical agent (CFR agent) is added to said rubber composition in at least one of said preparatory rubber mixing stage(s), wherein said CFR agent is a free radical-containing nitroxide compound reactive with said created free radicals on said elastomer chain to thereby form a CFR treated elastomer; (C) sulfur curing said mixed rubber composition at an elevated temperature in a range of from about 130° C. to about 180° C. during which said CFR agent is liberated from said elastomer at the elevated temperature to create subsequent free radicals on the elastomer chain; an improvement which comprises addition of a free radical reactive compound (FRRC) to said rubber composition containing said CFR treated elastomer in said productive rubber mixing stage, wherein said FRRC is reactive with said subsequently created free radicals formed on said elastomer chain by liberation of said CFR agent at said elevated processing temperature, to thereby form a FRRC treated elastomer; wherein said CFR agent is comprised of 2,2,6,6-tetramethylpiperidine-1,4-diol and derivatives thereof so long as said derivatives contain nitroxide free radicals and are reactive with said created free radicals on said elastomer chain and 2,2,5,5-tetramethyl- 1-pyrrolidinyloxy and derivatives thereof so long as said derivatives contain nitroxide free radicals and are reactive with said created free radicals on said elastomer chain; wherein said FRRC is comprised of at least one of , zinc acrylates, di-acrylates and tri-acrylates; triallyl cyanurates; triallyl phosphates; and high vinyl polybutadiene resin having a vinyl content in a range of from about 40 to about 80 percent.