Golf ball and manufacturing method of golf ball core

Abstract

A golf ball core and a method of making the same wherein remarkable reduction of eccentricity of an inner layer to an outer layer is accomplished, and mass-production of the golfball cores are possible. The golfball inner layer is penetrated into at least a part of a seam portion of the outer layer. A volume of an intrusive portion of the inner layer into the outer layer is arranged to be 1/300 to 1/5 of a volume of the outer layer, suppose the outer layer is a complete spherical shell. To form a core, an unvulcanized material is semi-vulcanized or vulcanized to form an outer layer half shell whose configuration is generally a hemispherical shell, and an unvulcanized inner layer forming material is put between the pair of outer layer half shells and vulcanizing pressed.