Preparation of silica-rich rubber composition by sequential mixing with maximum mixing temperature limitations

The invention relates to preparation of silica-rich rubber compositions by a sequence of sequential mixing steps conducted in internal rubber mixer(s) with individual maximum temperature limitations. The mixing steps are comprised of at least two non-productive mixing steps followed by a productive mixing step. The non-productive mixing steps themselves are comprised of at least one preliminary non-productive mixing step followed by a final non-productive mixing step. Elastomer, silica and coupling agent are added in at least one of said preliminary non-productive mixing steps to the exclusion of said final non-productive mixing step and said productive mixing step. Sulfur and sulfur vulcanization accelerator(s) are added in said productive mixing step to the exclusion of said non-productive mixing steps. The preliminary non-productive mixing step(s) are individually conducted to a maximum mixing temperature in a range of from about 150° C. to about 180° followed by the final non-productive mixing step to a reduced maximum mixing temperature in a range of from about 90° C. to about 130° C. The maximum mixing temperature of said final non-productive mixing step is at least 20° C. lower than the maximum temperature for said preliminary non-productive mixing stage(s). The productive mixing step is conducted to a maximum temperature in a range of from about 90° C. to about 120° C. The rubber composition is removed from its respective internal rubber mixer and cooled to below 40° C. between said mixing steps. The invention is further intended to relate to a rubber composition prepared by such mixing process and to a tire having at least one component comprised of such rubber composition.