Patent ID: 7244192

Claim:
A golf ball comprising a core formed by vulcanizing and press-molding a rubber composition and at least one layer of a cover covering the core, wherein the rubber composition comprises a base rubber, a co-crosslinking agent, an organic peroxide, a filler and a processing aid, the base rubber comprises a polybutadiene (a) containing a cis-1,4 bond of not less than 80% and synthesized using lanthanide-containing catalyst, the organic peroxide comprises an organic peroxide having 10 hours half-life period temperature of 80 to 100° C., the processing aid is fatty acid ester, fatty acid salt or a mixture thereof, and the polybutadiene (a) has a ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 2.5 to 3.5, and the core has a center hardness in JIS-C hardness of 50 to 70, a surface hardness in JIS-C hardness of 70 to 90 and a hardness difference (B-A) between the surface hardness (B) and the center hardness (A) of 15 to 28.