Abstract: The present invention provides a multi-piece solid golf ball having excellent flight performance and excellent shot feel at the time of hitting, and a method of making the same having good workability. The present invention relates to a multi-piece solid golf ball comprising a core composed of a center and at least one core outer layer formed on the center, and a cover covering the core, wherein the core outer layer is formed from a rubber composition which does not contain zinc salt of unsaturated carboxylic acid.

Abstract: A golf ball 1 has a core 2, a cover 3, a mark layer 4, and a finishing coat layer 5. An ink used for the mark layer 4 includes an isocyanate curing agent that contains a diisocyanate trimer, a base material, and a colorant. Preferred curing agent contains an isophorone diisocyanate trimer. The ink includes a diisocyanate curing agent at equal to or greater than 1% by weight and equal to or less than 20% by weight, calculated on the basis of the solid content. The base material includes a polymer having a hydroxyl group as a principal component. The “NCO/OH” value, which is a ratio of isocyanate groups of the isocyanate curing agent and hydroxyl groups of the base material, is equal to or greater than 0.5 and equal to or less than 2.0. The mark layer 4 may be printed on a base coat layer, alternatively, may be printed on a crosslinked rubber. This ink has excellent adhesiveness to a base.

Abstract: A golf ball 1 has a core 2, a cover 3, a mark layer 4, and a finishing coat layer 5. An ink used for the mark layer 4 includes an isocyanate curing agent that contains a diisocyanate trimer, a base material, and a colorant. Preferred curing agent contains an isophorone diisocyanate trimer. The ink includes a diisocyanate curing agent at equal to or greater than 1% by weight and equal to or less than 20% by weight, calculated on the basis of the solid content. The base material includes a polymer having a hydroxyl group as a principal component. The “NCO/OH” value, which is a ratio of isocyanate groups of the isocyanate curing agent and hydroxyl groups of the base material, is equal to or greater than 0.5 and equal to or less than 2.0. The mark layer 4 may be printed on a base coat layer, alternatively, may be printed on a crosslinked rubber. This ink has excellent adhesiveness to a base.

Abstract: A pair of unvulcanized half outer layer bodies are formed by metallic molds provided with first mold having a hemispherical convex portion and second mold having a hemispherical concave portion. A vulcanized inner core is put into either of half outer layer bodies, and a pair of half outer layer bodies are paired up to form a preparatory form which is to be vulcanization molded in metallic molds for vulcanization molding.

Abstract: The present invention provides a multi-piece solid golf ball having excellent flight performance and excellent shot feel at the time of hitting, and a method of making the same having good workability. The present invention relates to a multi-piece solid golf ball comprising a core composed of a center and at least one core outer layer formed on the center, and a cover covering the core, wherein the core outer layer is formed from a rubber composition which does not contain zinc salt of unsaturated carboxylic acid.

Abstract: A spherical object is positioned on a rotation stage, the rotation stage is rotated, and a deviation detector detects whether the spherical object deviates from the rotation stage or not. A rotation frequency of the rotation stage when the object deviates from the rotation stage is detected by a rotation frequency detector, and a judgement system judges whether the object is mass eccentric or not, comparing the detected rotation frequency with a predetermined rotation frequency which is set beforehand.

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.

Abstract: A pair of unvulcanized half outer layer bodies are formed by metallic molds provided with first mold having a hemispherical convex portion and second mold having a hemispherical concave portion. A vulcanized inner core is put into either of half outer layer bodies, and a pair of half outer layer bodies are paired up to form a preparatory form which is to be vulcanization molded in metallic molds for vulcanization molding.

Abstract: A plurality of small-sized recesses are provided along outer peripheral edges of the openings of semispheric recessed portions in which a golf ball is injection-molded. These small-sized recesses form small-sized positioning juts along the parting line of a golf ball intended to be injection-molded.