Golf ball

Abstract

A golf ball 2 includes a core 4, an inner cover 6, and an outer cover 8. The golf ball 2 satisfies the following mathematical formulas (1), (2), and (3):5≤(Hi*Ti−Dc*Rc)≤40  (1);5≤(Hi*Ti−Ho*To)≤40  (2); and−20≤(Ho*To−Dc*Rc)≤20  (3).Dc is the amount of compressive deformation (mm) of the core 4,Rc is the radius (mm) of the core 4,Hi is the Shore C hardness of the inner cover 6,Ti is the thickness (mm) of the inner cover 6,Ho is the Shore C hardness of the outer cover 8, andTo is the thickness (mm) of the outer cover 8.

What is claimed is: 
     
         1 . A golf ball comprising:
 a core;   an inner cover positioned outside the core; and   an outer cover positioned outside the inner cover, wherein   the golf ball satisfies the following mathematical formulas (1), (2), and (3):
   5≤( Hi*Ti−Dc*Rc )≤40  (1);
 
   5≤( Hi*Ti−Ho*To )≤40  (2); and
 
   −20≤( Ho*To−Dc*Rc )≤20  (3), wherein
 
   Dc is an amount of compressive deformation (mm) of the core,   Rc is a radius (mm) of the core,   Hi is a Shore C hardness of the inner cover,   Ti is a thickness (mm) of the inner cover,   Ho is a Shore C hardness of the outer cover, and   To is a thickness (mm) of the outer cover.   
     
     
         2 . The golf ball according to  claim 1 , wherein the hardness Ho is lower than the hardness Hi. 
     
     
         3 . The golf ball according to  claim 2 , wherein a difference (Hi−Ho) between the hardness Hi and the hardness Ho is not less than 5. 
     
     
         4 . The golf ball according to  claim 1 , wherein an amount of compressive deformation Db of the golf ball is not less than 2.75 mm. 
     
     
         5 . The golf ball according to  claim 1 , wherein
 the inner cover is formed from a resin composition, and   a base material of the resin composition is an ionomer resin.   
     
     
         6 . The golf ball according to  claim 1 , wherein
 the outer cover is formed from a resin composition, and   a base material of the resin composition is an ionomer resin.   
     
     
         7 . The golf ball according to  claim 1 , wherein the difference (Hi*Ti−Dc*Rc) is not less than 17 and not greater than 24. 
     
     
         8 . The golf ball according to  claim 1 , wherein the difference (Hi*Ti−Ho*To) is not less than 17 and not greater than 35. 
     
     
         9 . The golf ball according to  claim 1 , wherein the difference (Ho*To−Dc*Rc) is not less than −14 and not greater than 8.