Patent ID: 8882610
Filing Date: 2014-11-11
Classification: A63B,C09J

Abstract:
1. A golf ball comprising a core, a mid layer positioned outside the core, and a cover positioned outside the mid layer, wherein the core comprises a center and an envelope layer positioned outside the center, the hardness of the center hardness gradually increases from its central point to its surface, the hardness of the envelope layer gradually increases from its innermost portion to its surface, a ratio of a volume of the core to a volume of a phantom sphere of the golf ball is equal to or greater than 76%, a difference (He−Ho) between a JIS-C hardness He at a surface of the core and a JIS-C hardness Ho at a central point of the core is equal to or greater than 15 but equal to or less than 30, a JIS-C hardness He of the cover is less than the hardness Ho, at all points P included in a zone that extends over a distance range from equal to or greater than 1 mm to equal to or less than 15 mm from the central point of the core, the following mathematical formula is satisfied, and in the mathematical formula, H1 indicates a JIS-C hardness at a point P1 that is located radially inward of each point P at a distance of 1 mm from the point P, and H2 indicates a JIS-C hardness at a point P2 that is located radially outward of each point P at a distance of 1 mm from the point P.