Elastomer compositions and methods

Abstract

Novel methods of making elastomer compositions irclude the use of certain modifying agents and mechanical working prior to incorporation of a vulcanization system in a first or other early stage of a multi-stage process particulate filler, such as carbon black, and sulfur cross-linking agent are substantially dispersed into sulfur crosslinkable hydrocarbon elastomer. The particulate filler and sulfur crosslinking agent can be pre-mixed together as a pre-blend prior to being added to the elastomer. A substantially unvulcanized, processable elastomer is produced by the multi-stage process, involving further mechanical working of the initial masterbatch. A curative additive comprising accelerator, and optionally additional sulfur crosslinking agent, can be added and dispersed in the elastomer to produce a vulcanizable composition. In accordance with another aspect, extender oil is added to the elastomer subsequent to addition and substantial dispersion of the filler and sulfur crosslinking agent into the elastomer in the aforesaid early stage of the multi-stage process. Significant improvement in performance characteristics is achieved, especially by preferred embodiments, including good abrasion resistance and low hysteresis measured, for example, as tan delta-max at 70° C. The present invention further relates to novel unvulcanized, processable elastomer compositions comprising certain treated carbon black particulate filler and certain pre-vulcanization modifier in an amount effective to substantially increase bound rubber content in a substantially unvulcanized processable elastomer product of a non-productive thermo-mechanical working of the elastomer composition.