Patent ID: 7101922

Claim:
A method for preparing an elastomer/silica composite comprised of at least one elastomer and a homogeneously dispersed silica reinforcement therein and an emulsion of oil and an organosilane polysulfide dispersed therein which comprises, based upon parts by weight of an ingredient per 100 parts by weight rubber: (A) preparing a water dispersion of a composite formed by blending an aqueous colloidal silica slurry, rubber latex comprised of colloidal elastomer particles therein, and an emulsion of oil and an organosilane polysulfide by blending: (1) an aqueous suspension of negatively charged colloidal silica aggregates which contains from about 10 to about 100 phr of silica aggregates therein, (2) an aqueous rubber latex which is comprised of water and colloidal particles of a diene-based rubber and which contains 100 phr of diene-based rubber colloidal particles therein, and (3) an oil emulsion of an organosilane polysulfide having from 2 to 6, with an average of from 2 to 2.6 or from 3.5 to 4, sulfur atoms in its polysulfidic bridge, which contains from 0.4 to about 4 phr of said organosilane polysulfide therein, wherein said organosilane component of said organosilane polysulfide is reactive with silanol groups contained on the surface of said silica aggregates, wherein the oil of said oil emulsion is chemically inert insofar as said organosilane polysulfide is concerned, wherein said oil emulsion protects said organosilane polysulfide from hydrolysis from exposure to the water of said aqueous emulsion of colloidal particles of said diene-based rubber, and (B) recovering said elastomer/silica composite by coagulation to form a rubber composite.