Additive for rubber composition, additive composition for rubber composition, rubber composition and tire

摘要

An additive for a rubber composition consists essentially of an ester of (i) an aliphatic polyvalent carboxylic acid with (iii) a (poly)oxyalkylene derivative, and having at least one carboxyl group in its molecule, or an ester of (ii) an aromatic polyvalent carboxylic acid with (iii) a (poly)oxyalkylene derivative, and having at least one carboxyl group bonded to an aromatic ring in its molecule. And also, it relates to an additive composition, a rubber composition and a pneumatic tire using such an additive for a rubber composition.