Multi-piece solid golf ball

Abstract

A multi-piece solid golf ball has a core, at least one intermediate layer and an outer layer. The core is formed of a single layer or of two or more layers. The interior hardness profile of the core is set in a specific range, and the relationship between the compressive deformations of the core and the golf ball under given loadings is set in a specific range. The outer layer is formed primarily of a thermoplastic polyurethane material, and has a material hardness that is set in a specific range.

1 . A multi-piece solid golf ball comprising a core, at least one intermediate layer and an outer layer, wherein the core is formed of a single layer or of two or more layers;
 letting Ho be a JIS-C hardness at a center of the core and Hu be a JIS-C hardness at a surface of the core, the JIS-C hardness Ho is from 30 to 65, the JIS-C hardness Hu is from 65 to 90 and Hu−Ho is at least 20; letting D (mm) be a radius of the core, the core has a hardness profile in which the hardness does not decrease toward the core surface from a position 55% of D from the core center; letting (A) be the compressive deformation (mm) of the core when compressed under a final load of 450 kgf from an initial load state of 10 kgf and (B) be the compressive deformation (mm) of the golf ball when compressed under a final load of 600 kgf from an initial load state of 10 kgf, the value (A)-(B) is in the range of from −0.4 to 2.5; the outer layer is formed primary of a thermoplastic polyurethane material; and the outer layer has a Shore D material hardness of more than 50 and not more than 60.   
     
     
         2 . The multi-piece solid golf ball of  claim 1  wherein, letting (A) be the compressive deformation (mm) of the core when compressed under a final load of 450 kgf from an initial load state of 10 kgf, and (C) be the compressive deformation (mm) of the golf ball when compressed under a final load of 450 kgf from an initial load state of 10 kgf, the value (A)-(C) is in the range of from 0 to 5.5. 
     
     
         3 . The multi-piece solid golf ball of  claim 1 , wherein the core has a diameter of from 30 to 39.2 mm. 
     
     
         4 . The multi-piece solid golf ball of  claim 1 , wherein the intermediate layer is formed primarily of a mixture obtained by blending:
 (f) 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 admixed 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;   (e) a non-ionomeric thermoplastic elastomer;   (c) from 5 to 80 parts by weight of a fatty acid and/or fatty acid derivative having a molecular weight of from 228 to 1500; and   (d) from 0.1 to 17 parts by weight of a basic metal compound capable of neutralizing un-neutralized acid groups in the base resin and component (c).   
     
     
         5 . The multi-piece solid golf ball of  claim 1 , wherein the intermediate layer has a Shore D material hardness of not more than 65. 
     
     
         6 . The multi-piece solid golf ball of  claim 1 , wherein the outer layer has a thickness of from 0.3 to 1.5 mm.