Ube Industries, Inc.

Sumitomo Rubber Industries Limited

Mitsuharu Ambe

Takeshi Shoda

Yuuto Kanou

Takahiro Mabuchi

Toshifumi Haba

The present invention provides a rubber composition for a tire having improved workability and abrasion resistance. A rubber composition for a tire according to the present invention comprises: a polybutadiene which has: (A) a Mooney viscosity (ML) being 43 or more; (B) a ratio (Tcp/ML) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML) being 0.9 to 2.3; (C) a stress relaxation time (T80) being 10.0 to 40.0 seconds, which is a time until a torque is attenuated by 80% when the torque at the end of MLmeasurement is 100%; and (D) a molecular weight distribution (Mw/Mn) being 2.50 to 4.00; another rubber (ii); and a rubber reinforcing material (iii).

Rubber composition for tire

The present invention provides a polybutadiene having improved workability and abrasion resistance. A polybutadiene according to the present invention has: (A) a Mooney viscosity (ML) being 43 or more; (B) a ratio (Tcp/ML) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML) being 0.9 to 2.3; (C) a stress relaxation time (T80) being 10.0 to 40.0 seconds, which is a time until a torque is attenuated by 80% when the torque at the end of MLmeasurement is 100%; and (D) a molecular weight distribution (Mw/Mn) being 2.50 to 4.00.

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Ichihara, Japan

Mitsuharu Ambe