Golf ball

Abstract

In a golf ball having a core of at least one layer and a cover encasing the core, the cover is formed of a resin composition composed primarily of a polyurethane or a polyurea. Letting HMa (N/mm2) be the Martens hardness of the cover measured at a position 0.3 mm toward the center of the ball from the cover surface and ηIta (%) be the elastic recovery of the cover, HMa and ηIta satisfy the following conditions: (1) ηIta≥−1.16×HMa+79, (2) 10.0≤HMa≤38.0, and (3) 40≤ηIta≤80. The ball has an excellent spin performance on approach shots and an excellent scuff resistance.

1 . A golf ball comprising a core of at least one layer and a cover encasing the core, wherein the cover is formed of a resin composition composed primarily of a polyurethane or a polyurea and, letting HMa (N/mm 2 ) be the Martens hardness of the cover measured at a position 0.3 mm toward the center of the ball from the cover surface and ηIta (%) be the elastic recovery of the cover, HMa and ηIta satisfy conditions (1) to (3) below:
   η Ita≥− 1.16× HMa+ 79  (1),
 
   10.0≤ HMa≤ 38.0  (2), and
 
   40≤η Ita≤ 80  (3).
 
 
     
     
         2 . The golf ball of  claim 1 , wherein the Martens hardness of the cover (HMa) is from 11.0 to 24.0 N/mm 2 . 
     
     
         3 . The golf ball of  claim 1 , wherein the elastic recovery of the cover (ηIta) is from 50 to 75%. 
     
     
         4 . The golf ball of  claim 1 , wherein the cover has a thickness of from 0.4 to 3.0 mm. 
     
     
         5 . The golf ball of  claim 1 , wherein the cover is formed of a thermoplastic composition containing a polyurethane, a polyurea or a mixture thereof. 
     
     
         6 . The golf ball of  claim 1 , wherein a coating is formed on a surface of the cover. 
     
     
         7 . The golf ball of  claim 6  wherein, letting HMb (N/mm 2 ) be the Martens hardness of the coating and letting ηItb (%) be the elastic recovery of the coating, HMb and ηItb satisfy conditions (4) and (5) below:
     HMb≤ 20.0  (4), and
 
   52≤η Itb≤ 82  (5).