Patent ID: 7559856

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 at least one layer of the cover is made of a heated mixture which includes (A) 100 parts by weight of an olefin-unsaturated carboxylic acid random copolymer and/or an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random copolymer, (B) from 5 to 80 parts by weight of a fatty acid having a molecular weight of at least 280 or a derivative thereof and (C) from 0.1 to 10 parts by weight of a basic inorganic metal compound capable of neutralizing acid groups in components A and B, and which has a melt index of at least 1.0 dg/min.