Multi-piece solid golf ball

Abstract

A golf ball having a core, a cover and at least one intermediate layer therebetween satisfies specific conditions concerning the relative surface hardnesses of the core, the intermediate layer-encased sphere and the ball, and has a specific core hardness profile. Also, the value V/H, where V is the initial velocity of the ball and H is the deflection of the ball under specific loading, is set within a specific range. The ball has a construction which, when used by the ordinary amateur golfer, reduces the spin rate on full shots, enabling good distances to be obtained both on shots with a driver and on shots with an iron. The ball also has a soft yet crisp feel at impact.

1 . A multi-piece solid golf ball comprising a core, a cover, and at least one intermediate layer therebetween, wherein the value obtained by subtracting a surface hardness of an intermediate layer-encased sphere from a surface hardness of the ball, expressed in terms of Shore D hardness, is from 7 to 15; the value obtained by subtracting a surface hardness of the core from the surface hardness of the intermediate layer-encased sphere, expressed in terms of Shore D hardness, is within ±6; in a core hardness profile, the JIS-C hardness at a center of the core is 55±5, the JIS-C hardness at a position 5 mm from the core center is 57±5, the JIS-C hardness at a position 10 mm from the core center is 57±5, the JIS-C hardness at a position 15 mm from the core center is 70±5, and the JIS-C hardness at the core surface is 79±5; the value obtained by subtracting the core center hardness from the core surface hardness, expressed in terms of JIS-C hardness, is at least 22; and letting V be the initial velocity (m/s) of the ball and H be the deflection (mm) of the ball when compressed under a final load of 1,275 N from an initial load of 98 N, the value V/H is from 18 to 24 m/s·mm −1 . 
     
     
         2 . The golf ball of  claim 1 , wherein the value obtained by subtracting the surface hardness of the intermediate layer-encased sphere from the surface hardness of the ball, expressed in terms of Shore D hardness, is from 8 to 13. 
     
     
         3 . The golf ball of  claim 1  wherein, in the core hardness profile, the JIS-C hardness at the core center is 55±3, the JIS-C hardness at a position 5 mm from the core center is 57±3, the JIS-C hardness at a position 10 mm from the core center is 57±3, the JIS-C hardness at a position 15 mm from the core center is 70±3, and the JIS-C hardness at the core surface is 79±3. 
     
     
         4 . The golf ball of  claim 1  wherein, in the core hardness profile, the JIS-C hardness at the core center is 55±2, the JIS-C hardness at a position 5 mm from the core center is 57±2, the JIS-C hardness at a position 10 mm from the core center is 57±2, the JIS-C hardness at a position 15 mm from the core center is 70±2, and the JIS-C hardness at the core surface is 79±2. 
     
     
         5 . The golf ball of  claim 1 , wherein the core hardness profile satisfies the conditions:
   0< C 10− Cc≦ 8,  (1)
       C 10− Cc<Cs−C 10, and  (2)
     15< Cs−C 10,  (3)
   where Cc is the JIS-C hardness at the core center, C10 is the JIS-C hardness at a position 10 mm from the core center, and Cs is the JIS-C hardness at the core surface.   
     
     
         6 . The golf ball of  claim 1  which satisfies the condition:
     PS   7   /S/H× 100≧6.20 (mm −1 ),  (4)
 
 where PS 7  is the pressed area (mm 2 ), defined as the area of the golf ball that comes into contact with a flat surface when the ball is subjected to a load of 6,864 N, S is the hypothetical planar area (mm 2 ), defined as the area of a cross-sectional circle along the ball diameter were the surface of the ball to be entirely free of dimples, and H is the deflection (mm) of the ball when compressed under a final load of 1,275 N from an initial load of 98 N. 
 
     
     
         7 . The golf ball of  claim 1  which satisfies the condition:
     PS   2   /S/H× 100≦1.85(mm −1 ),  (5)
 
 where PS 2  is the pressed area (mm 2 ), defined as the area of the golf ball that comes into contact with a flat surface when the ball is subjected to a load of 1,961 N, S is the hypothetical planar area (mm 2 ), defined as the area of a cross-sectional circle along the ball diameter were the surface of the ball to be entirely free of dimples, and H is the deflection (mm) of the ball when compressed under a final load of 1,275 N from an initial load of 98 N.