Patent ID: 7479533

Claim:
A golf ball comprising a core and one or more cover layer which encloses the core, wherein at least one cover layer is made of a thermoplastic polyurethane composition characterized by including at least 90 wt % of a thermoplastic polyurethane obtained by a polyurethane-forming reaction of an organic diisocyanate compound with a long-chain polyol and a chain extender, and wherein the thermoplastic polyurethane contained in the cover layer is characterized in that an inherent viscosity in a DMF solvent is larger than 1.5 dl/g and an inherent viscosity in a DMF solution containing 0.05 mol/L n-butylamine is larger than 0.5 dl/g, and the inherent viscosity in DMF is larger than the inherent viscosity in DMF of the thermoplastic polyurethane prior to molding, and the inherent viscosity in 0.05 mol/L n-butylamine-containing DMF solution is larger than the inherent viscosity in 0.05 mol/L n-butylamine-containing DMF solution of the thermoplastic polyurethane prior to molding, and the thermoplastic polyurethane making up the cover layer has a content of nitrogen atoms originating from the organic diisocyanate compound, expressed as a percentage of the weight of the long-chain polyol, the organic diisocyanate compound and the chain extender combined, within a range of 4.0 to 6.5 wt %.