Multi-piece solid golf ball

Abstract

In a multi-piece solid golf ball having a core, envelope layer, intermediate layer and cover, the core is formed primarily of a base rubber, the core has a diameter of at least 30 mm, the envelope layer is formed as two layers—an inner layer and an outer layer, and the intermediate layer and the cover are each formed as single layers of a resin material. The core and the respective layer-encased spheres have surface hardnesses which satisfy specific relationships, the Shore C hardness value obtained by subtracting the core center hardness from the core surface hardness is 16 or more, and certain layers have respective thicknesses which satisfy specific conditions. This ball achieves a good distance on full shots both with a driver and with irons, is superior in the short game, and moreover has a good feel at impact and an excellent scuff resistance.

1 . A multi-piece solid golf ball comprising a core, an envelope layer, an intermediate layer and a cover, wherein the core is formed primarily of a base rubber as one or more layer; the core as a whole has a diameter of at least 30 mm; the envelope layer is formed as two layers—an inner envelope layer and an outer envelope layer; the intermediate layer and the cover are each formed as single layers of a resin material; the core has a surface hardness, the sphere obtained by encasing the core with the inner envelope layer (inner envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the inner envelope layer-encased sphere with the outer envelope layer (outer envelope layer-encased sphere) has a surface hardness, the sphere obtained by encasing the outer envelope layer-encased sphere with the intermediate layer (intermediate layer-encased sphere) has a surface hardness and the ball has a surface hardness which together satisfy the following condition in which the hardnesses are Shore C hardness values:
 core surface hardness<surface hardness of inner envelope layer-encased sphere<surface hardness of outer envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere>ball surface hardness; 
 
       the Shore C hardness value obtained by subtracting the core center hardness from the core surface hardness is 16 or more; and the envelope layer, the intermediate layer and the cover have respective thicknesses which satisfy the following two conditions:
 cover thickness<intermediate layer thickness, and 
 outer envelope layer thickness<inner envelope layer thickness. 
 
     
     
         2 . The golf ball of  claim 1 , wherein the core center hardness (Cc), core surface hardness (Cs) and the hardness at a midpoint between the core surface and the core center (Cm) satisfy the condition:
   ( Cs−Cm )/( Cm−Cc )≥1.5.
   
     
     
         3 . The golf ball of  claim 1  which satisfies the condition:
   0.4≤( OE vh+IE vh )/Core  vh≤ 1.1,
 
 
       wherein Core vh is the volume (mm 3 ) of the core multiplied by the Shore C hardness at a midpoint between the core surface and the core center (Cm), IE vh is the volume (mm 3 ) of the inner envelope layer multiplied by the Shore C hardness at the surface of the inner envelope layer-encased sphere, and OE vh is the volume (mm 3 ) of the outer envelope layer multiplied by the Shore C hardness at the surface of the outer envelope layer-encased sphere. 
     
     
         4 . The golf ball of  claim 1  wherein, letting CL1 be the coefficient of lift at a Reynolds number of 80,000 and a spin rate of 2,000 rpm and CL2 be the coefficient of lift at a Reynolds number of 70,000 and a spin rate of 1,900 rpm, the ball satisfies the following condition:
   0.900≤ CL 2/ CL 1.
 
 
     
     
         5 . The golf ball of  claim 1  wherein, letting CL3 be the coefficient of lift at a Reynolds number of 200,000 and a spin rate of 2,500 rpm and CL4 be the coefficient of lift at a Reynolds number of 120,000 and a spin rate of 2,250 rpm, the ball satisfies the following condition:
   1.250≤ CL 4/ CL 3≤1.300.
 
 
     
     
         6 . The golf ball of  claim 1 , wherein the cover has a surface with from 323 to 380 dimples arranged thereon.