RUBBER COMPOSITION SUITABLE FOR AUTOMOBILE TIRES AND ITS PRODUCTION

摘要

A styrene/butadiene copolymer rubber to be used for automobile tires is lowered in its rolling resistance by blending it with carbon black and the following components (A) and (B): (A) a dinitrodiamine compound represented by the following formula (I): (I) wherein X is a divalent organic group such as an alkylene, R1 is hydrogen or an organic group such as an alkyl, provided that two nitrogen atoms linking through X may further link through R1, and R2 and R3 are each hydrogen or an alkyl, provided that R2 and R3 may conjointly form a ring; and (B) a sulfide compound selected from dibenzothiazyl disulfide, tetralkylthiuram disulfide, and alkyl- or hydroxy-substituted phenol sulfide resin. The dinitrodiamine compound (A) and the sulfide compound (B) are added simultaneously to the rubber together with the carbon black in a first kneading step of a high temperature. The resulting rubber composition is lowered in its loss factor (tan 6) at around 60.degree.C as compared with the case where the dinitrodiamine compound (A) is added alone, and it contributes to decrease the rolling resistance of tires made from the rubber composition.