Multi-piece solid golf ball

Abstract

In a multi-piece solid golf ball having a core, an intermediate layer and a cover, the cover is formed primarily of a polyurethane material, the ball has a higher surface hardness on the Shore C hardness scale than the sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere), and the ball has a deflection of at least 3.6 mm when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf). The golf ball has an excellent flight performance when hit by golfers whose head speeds are not very fast and moreover has a good, soft feel at impact, making it suitable for use by amateur golfers.

1 . A multi-piece solid golf ball comprising a core, an intermediate layer and a cover, wherein the cover is formed primarily of a polyurethane material, the ball has a higher surface hardness on the Shore C hardness scale than the sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere), and the ball has a deflection of at least 3.6 mm when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf). 
     
     
         2 . The golf ball of  claim 1 , wherein the core has a surface hardness and a center hardness such that the difference therebetween, expressed on the Shore C hardness scale, is at least 16. 
     
     
         3 . The golf ball of  claim 1 , wherein the core has a deflection of at least 3.8 mm when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf). 
     
     
         4 . The golf ball of  claim 1  wherein, in an impact test carried out by striking the ball with a driver at a head speed of 40 m/s, the time t 1  required from contact initiation between the driver and the ball for deformation of the ball to reach a maximum value and the time t 2  required from the state of maximum golf ball deformation for the ball and the driver to separate have a ratio t 2 /t 1  therebetween of at least 1.20. 
     
     
         5 . The golf ball of  claim 4 , wherein the sum of deformation times t 1  and t 2  is from 660 to 800 microseconds. 
     
     
         6 . The golf ball of  claim 1 , wherein the cover has a surface on which a coating layer is formed, which coating layer has a Shore C hardness of from 50 to 70. 
     
     
         7 . The golf ball of  claim 6 , wherein the value obtained by subtracting the Shore C hardness of the coating layer from the core center hardness (Shore C hardness) is at least 0.