Multi-piece solid golf ball

Abstract

In a golf ball having a core, a cover and an intermediate layer therebetween, the ball and a sphere consisting of the core encased by the intermediate layer have surface hardnesses which satisfy a specific relationship, the intermediate layer and the cover have thicknesses which satisfy a specific relationship, and (initial velocity of intermediate layer-encased sphere)/(initial velocity of core)≧0.995. Also, the core, the intermediate layer-encased sphere and the ball have respective deflections under given compression conditions which satisfy a specific condition. When used by golfers whose head speed is not very fast, the ball achieves a good distance on shots with a driver, in addition to which it has a soft feel and is able to retain a high spin performance on approach shots.

1 . A multi-piece solid golf comprising a core, a cover and an intermediate layer therebetween, wherein a sphere comprising the core and the intermediate layer which peripherally encases the core (intermediate layer-encased sphere) and the ball have respective surface hardnesses, expressed in terms of Shore D hardness, which satisfy the relationship:
   (Shore  D  hardness at ball surface)≦(Shore  D  hardness at surface of intermediate layer-encased sphere);  (1)
   the intermediate layer and the cover have respective thicknesses which satisfy the relationship:
   cover thickness≦intermediate layer thickness;  (2)
 
   the intermediate layer-encased sphere and the core have respective initial velocities which satisfy the relationship:
   (initial velocity of intermediate layer-encased sphere)/(initial velocity of core)≧0.995; and  (3)
 
   the core, the intermediate layer-encased sphere and the ball, when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf), have respective deflections (mm) A, B and C which satisfy the condition:
     A+B+C≧ 11.5,  (4)
 
   with the proviso that A≧4.0 and C≧3.2.   
     
     
         2 . The golf ball of  claim 1  which, in formula (3), satisfies the condition:
   (initial velocity of intermediate layer-encased sphere)/(initial velocity of core)≧1.004.
 
 
     
     
         3 . The golf ball of  claim 1  which, in formula (4), satisfies the condition (A−C)≧0.9. 
     
     
         4 . The golf ball of  claim 1  wherein the core has a hardness profile which, expressed in terms of JIS-C hardness, satisfies conditions (i) to (vi) below, wherein Cc is the JIS-C hardness at a center of the core, C5 is the JIS-C hardness at a position 5 mm from the core center, C10 is the JIS-C hardness at a position 10 mm from the core center, C15 is the JIS-C hardness at a position 15 mm from the core center, and Cs is the JIS-C hardness at a surface of the core:
   18≦ Cs−Cc,   (i)
 
   0< C 10− Cc≦ 10,  (ii)
 
     C 10− Cc<Cs−C 10,  (iii)
 
   10< Cs−C 10,  (iv)
 
     Cs≧ 68, and  (v)
 
     Cc≧ 48  (vi).
 
 
     
     
         5 . The golf ball of  claim 1  which further satisfies condition (iii-a) below:
   ( Cs−C 10)/( C 10− Cc )≧1.0  (iii-a).
 
 
     
     
         6 . The golf ball of  claim 1  which further satisfies condition (vii) below:
     Cs−Cc< 10  (vii).
 
 
     
     
         7 . The golf ball of  claim 1 , wherein the intermediate layer is formed of a material obtained by blending as essential components:
 100 parts by weight of a resin component comprising, in admixture,
 a base resin of (a) an olefin-unsaturated carboxylic acid random copolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer mixed with (b) an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer in a weight ratio between 100:0 and 0:100, and 
 (e) a non-ionomeric thermoplastic elastomer in a weight ratio between 100:0 and 50:50; 
   (c) 5 to 80 parts by weight of a fatty acid and/or fatty acid derivative having a molecular weight of from 228 to 1,500; and   (d) 0.1 to 17 parts by weight of a basic inorganic metal compound capable of neutralizing un-neutralized acid groups in the base resin and component (c).   
     
     
         8 . The golf ball of  claim 1 , wherein the ball, the intermediate layer-encased sphere and the core have respective initial velocities which satisfy the relationship:
   initial velocity of ball<initial velocity of core<initial velocity of envelope layer-encased sphere  (5).
   
     
     
         9 . The golf ball of  claim 1  which, in formula (1), satisfies the condition:
   (Shore  D  hardness at surface of intermediate layer-encased sphere)≧(Shore  D  hardness at core surface)  (1′).