Rubber processing aid, rubber composition to which it is added, and method for producing rubber composition

摘要

PROBLEM TO BE SOLVED: To provide a processing aid for a rubber useful in improving milling characteristics and processability, especially of a silica-loaded rubber composition, a rubber composition produced by adding the processing aid and a method for producing the rubber composition by adding a specified processing aid component. SOLUTION: A processing aid for a rubber is obtained by mixing a fatty acid obtained by hydrolyzing a castor oil and its derivative with an amine. As a derivative of the fatty acid, a ricinoleic acid that is the main component of the castor oil and a hydroxy acid is preferably used. As an amine, one capable of forming an amine salt with the fatty acid or the like can be used and especially, a primary monoamine is preferable. The processing aid can be used as a powder by adsorbing it onto a porous material, especially silica. A powder, if it is used at a low temperature in winter or the like, is free from solidification and is easily handled. The processing aid can be used by adding it to a variety of rubber components such as a natural rubber and a styrene-butadiene rubber.