Golf ball

Abstract

In a golf ball having a rubber core and a cover of at least one layer encasing the core, at least one cover layer is formed of a resin composition that includes a thermoplastic polyurethane and an inorganic filler. The inorganic filler content is at least 5 parts by weight per 100 parts by weight of the thermoplastic polyurethane. The resin composition has an abrasion volume in the Taber abrasion test according to JIS-K 7311 of more than 0.003 cm 3 and satisfies formula (1) below 7 . 0 × 1 ⁢ 0 4 > ( η1 - η2 ) / H 3 , ( 1 ) wherein H is the Shore D hardness and η1 and η2 are respectively the 210° C. and 220° C. melt viscosities (Pa·s) at a shear rate of 6,080 sec −1 when measured with a capillary rheometer in accordance with ISO 11443: 1995. The cover resin material has improved flowability when molded and improved trimmability after molding.

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 that includes components (I) and (II) below:
 (I) a thermoplastic polyurethane and   (II) an inorganic filler,   
       component (II) is included in an amount of at least 5 parts by weight per 100 parts by weight of component (I), and the resin composition has an abrasion volume after 1,000 rotations in a Taber abrasion test according to JIS-K 7311 of more than 0.003 cm 3  and satisfies formula (1) below 
       
         
           
             
               
                 
                   
                     
                       
                         
                           7 
                           . 
                           0 
                         
                         × 
                         1 
                         ⁢ 
                         
                           0 
                           
                             - 
                             4 
                           
                         
                       
                       > 
                       
                         
                           ( 
                           
                             η1 
                             - 
                             η2 
                           
                           ) 
                         
                         / 
                         
                           H 
                           3 
                         
                       
                     
                     , 
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
       H being the Shore D hardness of the resin composition and η1 and η2 being respectively the 210° C. and 220° C. melt viscosities (Pa·s) of the composition at a shear rate of 6,080 sec −1  when measured with a capillary rheometer in accordance with ISO 11443: 1995. 
     
     
         2 . The golf ball of  claim 1 , wherein the resin composition has a Shore D hardness of less than 50. 
     
     
         3 . The golf ball of  claim 1 , wherein component (II) is titanium oxide. 
     
     
         4 . The golf ball of  claim 3 , wherein the titanium oxide has an average particle size of at least 0.21 μm. 
     
     
         5 . The golf ball of  claim 1 , wherein melt viscosity η1 is 200 Pa·s or less. 
     
     
         6 . The golf ball of  claim 1 , wherein melt viscosity η2 is 150 Pa·s or less.