Patent ID: 6383091
Filing Date: 2002-05-07
Classification: A63B

Abstract:
A golfball, comprising: a core having a deflection under load of 100 Kg of 2.5-5.0 mm, an intermediate layer around the core, and a cover around the intermediate layer, wherein the intermediate layer is a material selected from the group consisting of polyester elastomer, ionomer resin, styrene elastomer, hydrogenated butadiene rubber and mixtures thereof, said cover is a material selected from the group consisting of ionomer resin, polyurethane resin, polyester resin and balata, and is integrally provided with a plurality of protrusions penetrating into the intermediate layer distributed on the spherical surface of said intermediate layer in a regular octahedral arrangement or a regular icosahedral arrangement, the protrusions having a Shore D hardness which is at least 8 units higher than the Shore D hardness of the intermediate layer, each of said protrusions satisfying the relationship:L>&pgr;(EI/A&sgr;b)Â½wherein L is the length (mm) of the protrusion, E is the Young's modulus (MPa) of the material of the protrusion, I is the geometrical moment of inertia (mm4) of the protrusion, A is the cross-sectional area (mm2) of the protrusion, and &sgr;b is the yield stress (MPa) of the protrusion.