Rubber composition for tire, pneumatic tire, and method for manufacturing rubber composition for tire

A rubber composition for tires, comprising:

• a rubber component;
• a phenylenediamine antioxidant;
• at least one nonionic surfactant selected from the group consisting of a poloxamer nonionic surfactant, a nonionic surfactant of Formula (1), and a nonionic surfactant of Formula (2) below;
• carbon black;
• silica;
• stearic acid;
• and
• a vulcanization accelerator represented by Formula (3) below,
• the rubber component comprising a diene rubber in an amount of 70% to 100% by mass based on 100% by mass of the rubber component,
• the rubber composition comprising, per 100 parts by mass of the rubber component, 1.0 to 10.0 parts by mass of the phenylenediamine antioxidant, a total of 0.1 to 5.0 parts by mass of the at least one nonionic surfactant, 46 parts by mass or more of the carbon black, 15 parts by mass or less of the silica, and 2.2 to 4.0 parts by mass of the stearic acid,
• wherein R1 represents a C6-C26 hydrocarbon group, and d represents an integer,
• wherein R2 and R3 are the same as or different from one another and each represent a C6-C26 hydrocarbon group, and e represents an integer,
• wherein R11 represents a C2-C16 alkyl group, and R12 represents a C3-C16 branched alkyl group or a benzothiazolylsulfide group.

A method for producing a rubber composition for tires, the method comprising:

• a base kneading step including mixing and kneading a rubber component and a phenylenediamine antioxidant;
• and
• a final kneading step including adding a vulcanizing agent and a masterbatch to a mixture obtained in the base kneading step and kneading them,
• the masterbatch comprising a nonionic surfactant and a silica having a BET value of 40 to 250 m2/g at a mass ratio of 1:5 to 1:0.15, the nonionic surfactant being at least one selected from the group consisting of a poloxamer nonionic surfactant, a nonionic surfactant of Formula (1), and a nonionic surfactant of Formula (2) below,
• wherein R1 represents a C6-C26 hydrocarbon group, and d represents an integer,
• wherein R2 and R3 are the same as or different from one another and each represent a C6-C26 hydrocarbon group, and e represents an integer.