US 7,479,533 B2
	Golf ball
Hiroyuki Nagasawa, Chichibu (Japan); Yoshinori Egashira, Chichibu (Japan); Yoshihiro Yamana, Tokyo (Japan); Hidekazu Saito, Kurashiki (Japan); and Hiroki Kimura, Kurashiki (Japan)
Assigned to Bridgestone Sports Co., Ltd., Tokyo (Japan)
Filed on May 04, 2005, as Appl. No. 11/120,959.
Prior Publication US 2006/0252578 A1, Nov. 09, 2006
This patent is subject to a terminal disclaimer.
Int. Cl. A63B 37/12 (2006.01)

U.S. Cl. 528—76  [528/65; 528/66; 473/378]

12 Claims

1. 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 %.