Patent ID: 6858665

Claim:
A process of preparing a rubber composition which contains a dispersion of intercalated and at least partially exfoliated smectite clay, wherein said smectite clay is intercalated and exfoliated in situ within an elastomer host comprises blending, based upon parts by weight per 100 parts by weight rubber (phr): A. 100 phr of at least one hydrocarbon diene-based elastomer, B. about one to about 20 phr of said smectite clay selected from at least one of montmorillonite clay and hectorite clay and mixtures thereof, C. quaternary animonium salt selected from methyl trialkyl ammonium chloride, trimethyl alkyl ammonium chloride, dimethyl dialkyl animonium chloride, dimethyl alkyl allyl ammonium chloride and diniethyl diallyl ammonium chloride, and D. about 20 to about 99 phr of at least one additional reinforcing filler comprised of at least one of carbon black, synthetic amorphous silica or silica treated carbon black and mixtures thereof; wherein a coupling agent is mixed therewith subsequent to said intercalation of said smectite clay and after at least a partial exfoliation of said intercalated clay to form exfoliated clay platelets; wherein said coupling agent is a bis(3-triethoxysilylpropyl) polysulfide having an average of from about 2 to about 2.6 or an average of from about 3.5 to about 4 connecting sulfur atoms in its polysulfidic bridge.