Patent ID: 6211271
Filing Date: 2001-04-03
Classification: C08J

Abstract:
A process for producing a vulcanizable rubber composition including carbon black-based and silica-based reinforcing fillers, characterized in that comprises the steps ofa) intimately mixing at a temperature of from 130.degree. to 180.degree. C.:i) at least a first cross-linkable unsaturated chain polymer;ii) a first carbon black-based reinforcing filler, and optionallyiii) one or more non cross-linking ingredients to obtain a first rubber composition having a Mooney viscosity of from 70 to 140 Ms, wherein the first carbon black-based reinforcing filler Is dispersed in a substantially homogeneous manner;b) cooling the first rubber composition obtained from step a) to a temperature not exceeding 100.degree. C.,c) intimately mixing at a temperature of from 130.degree. to 180.degree. C.:i) the first high-viscosity rubber composition obtained from step b),ii) at least a second cross-linkable unsaturated chain polymer,iii) a second silica-based reinforcing filler, and optionallyiv) one or more non cross-linking ingredients to obtain a second rubber composition wherein the carbon black-based and silica-based reinforcing fillers are dispersed in a substantially homogeneous manner;d) intimately mixing the second rubber composition thus obtained with a suitable vulcanizing system at a temperature lower than the vulcanization temperature.