Additive for masticating natural rubber, mastication method of natural rubber, natural rubber composition obtained by the mastication method thereof, and pneumatic tire using the natural rubber composition thereof

摘要

An additive for masticating natural rubber comprising at least one compound selected from the group consisting of benzoic acids, naphthoic acids, dicarboxylic acids and compounds represented by Formula (IV): wherein m and n each represent an integer of 1 to 3; p represents an integer of 1 to 4; m+n+p=6; X is O, NR8 or (R9O)q; R6 is a C1 DIFFERENCE C24 alkyl, a C2 DIFFERENCE C24 alkenyl, or a C6 DIFFERENCE C24 aryl group; and R7 is H, OH, an alkyl, alkenyl or aryl group; R8 is H or a C1 DIFFERENCE C24 alkyl group; R9 is a C1 DIFFERENCE C4 alkyl group; q is an integer of 1 to 5, a mastication method and a natural rubber composition each of which uses the additive, and a pneumatic tire using the natural rubber composition.