Abstract: 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 (ML1+4,100° C.) being 43 or more; (B) a ratio (Tcp/ML1+4,100° C.) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML1+4,100° C.) 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 ML1+4,100° C. measurement 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).

Abstract: The present invention provides a polybutadiene having improved workability and abrasion resistance. A polybutadiene according to the present invention has: (A) a Mooney viscosity (ML1+4,100° C.) being 43 or more; (B) a ratio (Tcp/ML1+4,100° C.) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML1+4,100° C.) 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 ML1+4,100° C.measurement is 100%; and (D) a molecular weight distribution (Mw/Mn) being 2.50 to 4.00.

Abstract: 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 (ML1+4,100° C.) being 43 or more; (B) a ratio (Tcp/ML1+4,100° C.) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML1+4,100° C.) 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 ML1+4,100° C. measurement 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).

Abstract: The present invention provides a polybutadiene having improved workability and abrasion resistance. A polybutadiene according to the present invention has: (A) a Mooney viscosity (ML1+4,100° C.) being 43 or more; (B) a ratio (Tcp/ML1+4,100° C.) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML1+4,100° C.) 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 ML1+4,100° C.measurement is 100%; and (D) a molecular weight distribution (Mw/Mn) being 2.50 to 4.00.

Abstract: A modified conjugated diene polymer and a method for producing the same. A rubber composition using the same. A modified conjugated diene polymer obtained by polymerizing a conjugated diene compound using a catalyst including from (A) an yttrium compound having a bulky ligand represented by general formula (1), (B) an ionic compound formed of a non-coordinating anion and a cation, and (C) an organic metal compound of an element selected from the group consisting of group 2, group 12 and group 13 of the periodic table and modifying the conjugated diene polymer with a carbonyl compound, a method for producing the same, and a rubber composition using the same.