Patent ID: 7029614

Claim:
A method of making a multi-piece solid golf ball comprising the steps of: (a) molding a rubber composition for a center in a spherical shape to form an unvulcanized center, (b) placing a rubber composition for a core outer layer in a mold having a semi-spherical cavity, and either semi-vulcanizing the rubber composition or heating the rubber composition to such a degree that the rubber composition neither semi-vulcanizes nor shrinks between the semi-spherical cavity and a male plug mold to form a semi-vulcanized or unvulcanized semi-spherical half-shell for the core outer layer, (c) after removing the male plug mold, mounting the unvulcanized center formed in the step (a) on a concave portion of the semi-vulcanized or unvulcanized semi-spherical half-shell for the core outer layer, and covering the unvulcanized center with a semi-vulcanized or unvulcanized semi-spherical half-shell for the core outer layer separately formed in the same manner as set forth in the step (b) to integrally vulcanize and form a core, (d) optionally, repeating the step (c) to form a core having multiple core outer layers, and (e) covering the core with a cover, wherein the rubber composition for the core outer layer does not contain a zinc salt of an unsaturated carboxylic acid and the rubber composition for the center contains a zinc salt of an unsaturated carboxylic acid.