Patent ID: 7407449
Filing Date: 2008-08-05
Classification: A63B

Abstract:
1. A golf ball comprising a core, an outermost cover layer and an intermediate layer therebetween, 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 intermediate layer has a thickness of from 0.5 to 2.5 mm and is made primarily of a resin material obtained by blending together (I) a sodium ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer with (II) a magnesium ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer and having a Shore D hardness of from 55 to 70; and the outermost cover layer has a thickness of from 0.5 to 2.0 mm and is made primarily of a non-ionomeric resin material having a Shore D hardness of from 35 to 60.