Patent ID: 7959524

Claim:
A three-piece solid golf ball comprising a core obtained by molding under heat a rubber composition comprising a base rubber, a filler, an organic peroxide, an antioxidant and an α,β-unsaturated carboxylic acid, and a cover which encases the core and is composed of an inner layer and an outer layer, wherein the core has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) of at least 2.6 mm but not more than 4.8 mm; the inner cover layer has a Shore D hardness of 58 or less and is made of a heated mixture comprising: 100 parts by weight of one or a mixture of (a) an olefin-unsaturated carboxylic acid random copolymer and/or an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random copolymer, and (d) a metal ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random copolymer, (b) from 5 to 80 parts by weight of a fatty acid or fatty acid derivative having a molecular weight of at least 228, and (c) from 0.1 to 10 parts by weight of a basic inorganic metal compound which is capable of neutralizing acid groups in components (a) and/or (d) and in component (b); the outer cover layer is obtained by injection-molding a single resin composition consisting primarily of (A) a thermoplastic polyurethane and (B) a polyisocyanate compound, which resin composition has present therein a polyisocyanate compound within at least a portion of which all the isocyanate groups on the molecule remain in an unreacted state; and the cover layers have a combined thickness of at least 2.7 mm; wherein the single resin composition consists of a plurality of the same kinds of pellets; wherein the resin composition making up the outer cover layer further includes (C) a thermoplastic elastomer other than a thermoplastic polyurethane; and wherein the resin composition is prepared by mixing component (A) with component (B) and additionally mixing in component (C) and the mixture is made in an inert gas or in a vacuum state.