Patent ID: 8586680

Claim:
A rubber composition for golf ball, comprising a high cis-polybutadiene adjusted by blending high cis-polybutadienes of several types synthesized in the presence of a cobalt-based catalyst, and a crosslinking agent mixed by 10-50 weight parts on the basis of 100 weight parts of the high cis-polybutadiene, the high cis-polybutadienes each having a cis content of 95% or higher, wherein the high cis-polybutadiene satisfies the requirements of (a) a Mooney viscosity (ML) of more than 40 and not more than 55, (b) a molecular weight distribution [Weight average molecular weight (Mw)/Number average molecular weight (Mn)] of 3.0-4.2, (c) a velocity dependence index of Mooney viscosity (n-value) of 2.3-3.0 (the n-value being represented by Expression 1), and (d) a ratio (Tcp/ML) of 2,5-3,5 between a 5% toluene solution viscosity (Tcp) and a Mooney viscosity (ML), log( ML )=log( K )+ n −1 ×log( RS ) [Expression 1] where RS denotes the number of revolutions of the rotor per minute, and K is an arbitrary number.