Patent ID: 7241231

Claim:
A method for preparing a one-piece golf ball or the solid core of a multilayer structure solid golf ball having a solid core enclosed with a cover directly or via an intermediate layer, comprising the steps of dry blending 100 to 1,000 parts by weight of an unsaturated carboxylic acid metal salt with 100 parts by weight of a solid rubber having a Mooney viscosity (ML 1+4 , 100° C.) of 5 to 150 by using a mixing machine to prepare a dry preblend, wherein the unsaturated carboxylic acid metal salt is added in three or more divided portions at a temperature of 80 to 110° C., mixing the dry preblend with a base rubber, an organic peroxide and zinc oxide by using a mixing machine to prepare a rubber composition, wherein the amount of the unsaturated carboxylic acid metal salt in the rubber composition is 10 to 50 parts by weight per 100 parts by weight of the total amount of the solid rubber and the base rubber, and heat compression molding the rubber composition to prepare at least one said one-piece golf ball or said solid core.