Golf ball

Abstract

The invention provides a golf ball having a core and a cover of at least one layer. The core has a cross-sectional hardness which, letting R (mm) be the radius of the core, A be the JIS-C hardness at a center of the core, B be the JIS-C hardness at a position R/3 mm from the core center, C be the JIS-C hardness at a position R/1.8 mm from the core center, D be the JIS-C hardness at a position R/1.5 mm from the core center, and E be the JIS-C hardness at a surface of the core, satisfies the formulas (1) B−A<D−B, (2) C−A≦8, and (3) E−B≧15.

1 . A golf ball comprising a core and a cover of at least one layer, wherein the core has a cross-sectional hardness which, letting R (mm) be a radius of the core, A be a JIS-C hardness at a center of the core, B be a JIS-C hardness at a position R/3 mm from the core center, C be a JIS-C hardness at a position R/1.8 mm from the core center, D be a JIS-C hardness at a position R/1.5 mm from the core center, and E be a JIS-C hardness at a surface of the core, satisfies formulas (1) to (3) below:
     B−A<D−B    (1)
       C−A≦ 8   (2)
       E−B≧ 15.   (3)
   
     
     
         2 . The golf ball of  claim 1 , wherein the cover comprises an outermost layer and an intermediate layer interposed between the outermost layer and the core, and, letting F be a JIS-C hardness at a surface of a sphere composed of the core covered by the intermediate layer, the ball satisfies formula (4) below:
     F−B≧ 30.   (4)
   
     
     
         3 . The golf ball of  claim 1 , wherein the ball has a deflection, when compressed under a final load of 5,880 N (600 kgf) from an initial load state of 98 N (10 kgf), of from 7 to 10 mm. 
     
     
         4 . The golf ball of  claim 1 , wherein the core is formed of a rubber composition which includes an organic peroxide having a one-minute half-life temperature of from about 165° C. to about 185° C. and sulfur. 
     
     
         5 . The golf ball of  claim 1 , wherein the cover comprises an outermost layer and an intermediate layer interposed between the outermost layer and the core, and the ball has, at a surface of a sphere composed of the core covered by the intermediate layer, a JIS-C hardness of at least 90. 
     
     
         6 . The golf ball of  claim 1 , wherein the outermost layer of the cover contains a base resin comprising a polyurethane material having a Shore D hardness of from 40 to 60. 
     
     
         7 . The golf ball of  claim 1 , wherein the core has a diameter of from 32 to 41 mm. 
     
     
         8 . The golf ball of  claim 1 , wherein the core is composed of a single layer.