Patent attributes
The invention provides a solid golf ball having a solid core, a cover layer that encloses the core, and a plurality of dimples formed on an outside surface of an outermost layer of the cover. The solid core is formed of a rubber composition composed of 100 parts by weight of a base rubber that includes 60 to 100 parts by weight of a polybutadiene rubber having a cis-1,4 bond content of at least 60% and synthesized using a rare-earth catalyst, 0.1 to 5 parts by weight of an organosulfur compound, and an unsaturated carboxylic acid or a metal salt thereof, an organic peroxide and an inorganic filler. The solid core has a deformation, when subjected to loading from an initial load of 10 kgf to a final load of 130 kg, of 2.0 to 3.5 mm, and has a specific hardness distribution. The cover layer, which is formed by injection-molding a single resin composition of primarily (A) a thermoplastic polyurethane and (B) a polyisocyanate compound, and at least some polyisocyanate compound in which all the isocyanate groups on the molecule remain in an unreacted state is present in the resin composition, and has a thickness of 0.5 to 2.5 mm, a Shore D hardness at the surface of 50 to 70. The core has a surface hardness which is from 1 to 15 Shore D hardness units lower than the surface hardness of the core. The golf ball has a deformation, when subjected to loading from an initial load of 10 kgf to a final load of 130 kgf, of 2.0 to 2.9 mm. The solid golf ball is advantageous overall in competitive use.
