Elastomers compositions with dual phase aggregates and pre-vulcanization modifier

Abstract

Novel elastomeric compositions are disclosed, incorporating silicon-treated carbon black and pre-vulcanization modifier selected from non-silane polysulfidic organo-compounds. The silicon-treated carbon black particulate filler differs chemically and in its performance characteristics from simple mixtures of silica and carbon black fillers. The pre-vulcanization modifier is effective to substantially increase bound rubber content in the product of a non-productive thermomechanical working of a base composition incorporating the silicon-treated carbon black particulate filler and SBR or other such unsaturated elastomer. The thermal working takes place at a maximum temperature sufficient to vulcanize the unsaturated elastomer if it were in the presence of a suitable vulcanization system. The non-vulcanized rubber masterbatch produced by such thermal working, having substantially increased bound rubber content, can be admixed with a vulcanization system in a thermomechanical finishing step carried out at a maximum temperature less than the vulcanization temperature. The resulting composition can be vulcanized by thermomechanical working at or above the vulcanization temperature. The resulting elastomeric compositions in accordance with preferred embodiments are found to have improved performance characteristics, including hysterisis balance of low temperature traction and high temperature rolling resistance.