Silica reinforced rubber composition and use in tires

摘要

This invention relates to a method of preparing a rubber composition comprising the sequential steps of, based upon parts by weight per 100 parts by weight rubber (phr):
(A) mixing in a non-productive mixing step, in the absence of sulfur and sulfur cure accelerator, in an internal rubber mixer to a temperature within a range of 140°C to 190°C:
(1) 100 parts by weight of a sulfur vulcanizable diene-based elastomer selected from conjugated diene homopolymers and copolymers and copolymers of vinyl aromatic compound and at least one conjugated diene;
(2) 10 to 120 phr of particulate reinforcing filler wherein said reinforcing filler comprises from 10 to 120 phr of silica;
(3) an oligomeric organomercaptosilane based coupling agent, and
(4) a combination of zinc oxide and carboxylic acid composed of from 1 to 7 phr of zinc oxide and from 1.5 to 8 phr of carboxylic acid, wherein the weight ratio of the carboxylic acid to the zinc oxide is at least 1/1;
wherein said zinc oxide and said carboxylic acid are added coincidentally with or prior to the addition of said organomercaptosilane oligomer;
(B) subsequently blending with the resultant rubber composition of said non-productive mixing step(s), in a thermomechanical productive mixing step at a temperature in a range of 100°C to 120°C, sulfur and at least one sulfur vulcanization accelerator.