Patent ID: 7329194
Filing Date: 2008-02-12
Classification: A63B

Abstract:
1. A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover which encases the intermediate layer and has formed on a surface thereof a plurality of dimples, wherein the core is formed primarily of a rubber material, has a diameter of at least 31 mm, and has a hardness which gradually increases from a center to a surface thereof, the hardness difference in JIS-C hardness units between the core center and the core surface being at least 15 and, letting (I) be the average value for cross-sectional hardnesses at a position 15 mm from the core center and at the core center and letting (II) be the cross-sectional hardness at a position 7.5 mm from the core center, the hardness difference (I)−(II) therebetween in JIS-C units being not more than ±2; the envelope layer and the intermediate layer are each formed primarily of the same or different resin materials; the cover is formed primarily of a thermoplastic resin or a thermoplastic elastomer; the envelope layer, intermediate layer and cover have thicknesses which satisfy the relationship and the envelope layer, intermediate layer and cover have surface hardnesses (JIS-C hardness) which satisfy the relationship