Patent ID: 7563181
Filing Date: 2009-07-21
Classification: A63B,C08K

Abstract:
1. A golf ball comprising a core, an inner cover layer and an outer cover 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; the inner cover layer has a Shore D hardness of from 10 to 60; and the outer cover layer has a Shore D hardness of from 50 to 80 which is higher than the Shore D hardness of the inner cover layer.