Patent ID: 7148290

Claim:
A rubber composition for a golf ball comprising a base rubber, a co-crosslinking agent, an organic peroxide and an inorganic filler, wherein the base rubber is a polybutadiene mixture consisting of a polybutadiene (a) containing a cis-1,4 bond of not less than 80%, having a Mooney viscosity of not less than 30 to less than 50 ML 1+4(100° C.), synthesized using lanthanide-containing catalyst and a polybutadiene (b) containing a cis-1,4 bond of not less than 40%, having a Mooney viscosity of not less than 55 to less than 70 ML1+4(100° C.), a ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 1.0 to 3.0, synthesized using lanthanide-containing catalyst, a weight ratio (a)/(b) being 30/70 to 90/10.