Patent ID: 8207247

Claim:
A process for mixing a filler with a rubber blend composition containing an isoprene elastomer and a butadiene elastomer to form a mixed rubber composition, the process comprising the steps of: (a) combining an isoprene elastomer and a butadiene-containing elastomer, a filler and an antidegradant in a mixing vessel to form a master batch rubber blend composition, the antidegradant being a quinone, a quinone imine, a quinone diimine, or a combination thereof; (b) mixing the master batch rubber blend composition for a viscosity-reducing effective period of time to mix the master batch composition to a minimum viscosity of the master batch rubber blend composition; (c) discharging the master batch rubber blend composition from the mixing vessel at the minimum viscosity, the minimum viscosity occurring at a temperature of about 120-160° C.; and (d) optionally combining the mixed master batch composition discharged in step c with at least one sulfur-containing vulcanizing agent and vulcanization accelerator, and vulcanizing the resulting composition to form the vulcanized rubber composition.