Abstract: We provide a method for producing a rubber composition that includes a rubber component (A) including natural rubber, at least one filler (B) selected from an inorganic filler and carbon black, and a hydrazide compound (C), the method comprising compounding in an optional preliminary compounding stage and a plurality of compounding stages, and adding the hydrazide compound (C) and kneading in the preliminary compounding stage and/or a first compounding stage, the hydrazide compound (C) being represented by general formula (I): R—CONHNH2, where R represents an alkyl group having from 1 to 30 carbon atoms, a cycloalkyl group having from 3 to 30 carbon atoms, or an aryl group. We also provide a rubber composition produced with this method.

Abstract: We provide a method for producing a rubber composition that includes a rubber component (A) including natural rubber, at least one filler (B) selected from an inorganic filler and carbon black, and a hydrazide compound (C), the method comprising compounding in an optional preliminary compounding stage and a plurality of compounding stages, and adding the hydrazide compound (C) and kneading in the preliminary compounding stage and/or a first compounding stage, the hydrazide compound (C) being represented by general formula (I): R—CONHNH2, where R represents an alkyl group having from 1 to 30 carbon atoms, a cycloalkyl group having from 3 to 30 carbon atoms, or an aryl group. We also provide a rubber composition produced with this method.

Abstract: The present invention provides a modified natural rubber that offers higher efficiency of graft polymerization or attachment of a polar group-containing compounds, and that possesses excellent low loss factor, wear resistance and fracture resistance when used as a rubber composition, a rubber composition using the modified natural rubber and a tire using the rubber composition. In the present invention, a polar group-containing compound is graft polymerized or attached under mechanical shear force to a natural rubber raw material having a nitrogen content of 0.4 mass % or less.

Abstract: The present invention provides a modified natural rubber that offers higher efficiency of graft polymerization or attachment of a polar group-containing compounds, and that possesses excellent low loss factor, wear resistance and fracture resistance when used as a rubber composition, a rubber composition using the modified natural rubber and a tire using the rubber composition. In the present invention, a polar group-containing compound is graft polymerized or attached under mechanical shear force to a natural rubber raw material having a nitrogen content of 0.4 mass % or less.