	US 7,601,290 B2
	Method for producing 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. 11/120,957.
Prior Publication US 2006/0249880 A1, Nov. 09, 2006
Int. Cl. B29C 45/14 (2006.01)

U.S. Cl. 264—279.1 [264/236; 264/275; 264/328.17; 264/347]

6 Claims

1. A method of manufacturing golf balls composed of a core and a cover of one or more layer that encloses the core, at least one cover layer being 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, which thermoplastic polyurethane composition cover layer has an inherent viscosity in a DMF solvent of larger than 1.5 dl/g and an inherent viscosity in a 0.05 mol/L n-butylamine containing DMF solution of larger than 0.5 dl/g, the golf ball manufacturing method being characterized by:

conditioning the thermoplastic polyurethane, to a pre-processing moisture content of 500 ppm or less, then injection molding the moisture-conditioned thermoplastic polyurethane to form the thermoplastic polyurethane composition cover layer.