US Patent 7829604 Golf ball

The invention provides a golf ball composed of a hot-molded material obtained by vulcanizing a rubber composition made primarily of a base rubber and an unsaturated carboxylic acid or salt thereof, wherein the rubber composition additionally includes a vulcanized rubber powder from which soluble ingredients have been removed by liquid washing. The golf ball of the invention is able to increase the hardness (deflection) of the core and has an excellent durability, in addition to which it effectively re-uses vulcanized rubber powder that is a waste material and so is industrially beneficial by lowering manufacturing costs and reducing the burden on the environment.