Patent ID: 7637824

Claim:
A golf ball comprising a core and a cover of one or more layer, wherein the core is made of a material obtained by molding under heat a rubber composition comprising (a) a base rubber containing polybutadiene having a stress relaxation time (T 80 ), defined as the time in seconds from the moment when rotation is stopped immediately after measurement of the ML 1+4 (100° C.) value (the Mooney viscosity measured at 100° C. in accordance with ASTM D-1646-96) that is required for the ML 1+4 value to decrease 80%, of 3.5 or less, (b) an unsaturated carboxylic acid and/or a metal salt thereof, and (c) an organic peroxide, and wherein at least one layer of the cover is made of a material obtained by molding a mixture comprising: (A) 100 parts by weight of a metal ion-neutralized olefin-unsaturated carboxylic acid random copolymer having a Shore D hardness of at least 60; (B) 5 to 60 parts by weight of an unsaturated fatty acid; and (C) 1 to 10 parts by weight of a basic inorganic metal compound capable of neutralizing acid groups in components A and B.