Golf ball

Abstract

In a golf ball having a core and a cover of at least one layer encasing the core, at least one layer of the cover is formed of a resin composition which includes (I) a polyurethane or a polyurea, and (II) a core-shell polymer in which the core is a crosslinked acrylic rubber particle and the shell consists of an acrylic polymer, the amount of component (II) included per 100 parts by weight of component (I) is less than 15 parts by weight, and the CS 1 value calculated by formula (1) below CS 1 =( CV 50 −CV 12 )/38  (1) (wherein CV 50 is the coefficient of restitution at an incident velocity of 50.0 m/s and CV 12 is the coefficient of restitution at an incident velocity of 12.0 m/s) is larger than −4.08×10 −3 , thereby to have an excellent controllability, a good feel at impact on approach shots and a good scuff resistance.

1 . A golf ball comprising a rubber core of at least one layer and a cover of at least one layer encasing the core, wherein at least one layer of the cover is formed of a resin composition comprising:
 (I) a polyurethane or a polyurea, and   (II) a core-shell polymer in which the core is a crosslinked acrylic rubber particle and the shell consists of an acrylic polymer;   the amount of component (II) included per 100 parts by weight of component (I) is less than 15 parts by weight; and   the CS 1  value calculated by formula (1) below   
       
         
           
             
               
                 
                   
                     
                       C 
                       ⁢ 
                       
                         S 
                         1 
                       
                     
                     = 
                     
                       
                         ( 
                         
                           
                             C 
                             ⁢ 
                             
                               V 
                               
                                 5 
                                 ⁢ 
                                 0 
                               
                             
                           
                           - 
                           
                             C 
                             ⁢ 
                             
                               V 
                               
                                 1 
                                 ⁢ 
                                 2 
                               
                             
                           
                         
                         ) 
                       
                       / 
                       38 
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         (wherein CV 50  is the coefficient of restitution at an incident velocity of 50.0 m/s and CV 12 is the coefficient of restitution at an incident velocity of 12.0 m/s) is larger than −4.08×10 −3 . 
       
     
     
         2 . The golf ball of  claim 1 , wherein the CS 2  value calculated by formula (2) below 
       
         
           
             
               
                 
                   
                     
                       C 
                       ⁢ 
                       
                         S 
                         2 
                       
                     
                     = 
                     
                       
                         ( 
                         
                           1. 
                           - 
                           
                             CV 
                             
                               1 
                               ⁢ 
                               
                                 2 
                                 / 
                                 4 
                               
                               ⁢ 
                               5 
                             
                           
                         
                         ) 
                       
                       / 
                       33 
                     
                   
                 
                 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
         (wherein CV 12/45  is the coefficient of restitution at an incident velocity of 12.0 m/s when the coefficient of restitution at an incident velocity of 45.0 m/s is set to 1.0) is larger than −5.23×10 −3 . 
       
     
     
         3 . The golf ball of  claim 1 , wherein component (II) does not include a plasticizer. 
     
     
         4 . The golf ball of  claim 1 , wherein component (II) has a melt flow rate (MFR), as measured at 230° C. and under a load of 2.16 kgf (ISO 1133), which is 18 g/10 min or less. 
     
     
         5 . The golf ball of  claim 1 , wherein component (II) has a rebound resilience of 22% or less. 
     
     
         6 . The golf ball of  claim 1 , wherein component (II) has a Shore D hardness of from 22 to 40.