Patent ID: 7553243

Claim:
A golf ball having a core consisting of at least one layer and a cover covering the core, wherein at least one layer of the core is obtained by molding a rubber composition which comprises (a) a base rubber containing a polybutadiene obtained by polymerizing butadiene in the presence of a catalyst containing a cobalt salen complex and methylaluminoxane; (b) a co-crosslinking agent; and (c) a crosslinking agent, and the polybutadiene contains 98% or more of cis-1,4-bond and 1% or less of trans-1,4-bond, and the golf ball having a difference in hardness between surface hardness and center hardness of 20 or more, 40 or less in shore D hardness, a center hardness of 30 or more, 50 or less in shore D hardness and a surface hardness of 45 or more, 68 or less in shore D hardness.