Golf ball

Abstract

Golf ball 2 has spherical core 4, cover 6 situated on the external side of the core 4, and paint layer 8 situated on the external side of the cover 6. The cover 6 has a Shore D hardness of no greater than 61. The paint layer 8 has a Martens hardness of no greater than 2.0 mgf/μm 2 . The base polymer of the paint layer 8 is a polyurethane obtained by a reaction of a polyol with a polyisocyanate. The polyisocyanate contains a buret-modified form of hexamethylene diisocyanate. The cover 6 has a thickness of 0.3 mm or greater and 1.0 mm or less. The paint layer 8 has a thickness of 5 μm or greater and 40 μm or less.

What is claimed is: 
     
         1 . A golf ball comprising a core, a cover situated on the external side of the core, and a paint layer situated on the external side of the cover, wherein
 the cover has a Shore D hardness of no greater than 61, and   the paint layer has a Martens hardness of no greater than 2.0 mgf/μm 2 .   
     
     
         2 . The golf ball according to  claim 1 , wherein
 the base polymer of the paint layer is a polyurethane obtained by a reaction of a polyol with a polyisocyanate, and   the polyisocyanate contains a buret-modified form of hexamethylene diisocyanate.   
     
     
         3 . The golf ball according to  claim 2 , wherein the percentage of the buret-modified form relative to the total amount of the polyisocyanate is no less than 20% by weight. 
     
     
         4 . The golf ball according to  claim 1 , wherein
 the base polymer of the paint layer is a polyurethane obtained by a reaction of a polyol with a polyisocyanate, and   the NCO/OH ratio in the polyurethane is 1.0/1.0 or greater and 1.4/1.0 or less.   
     
     
         5 . The golf ball according to  claim 1 , wherein
 the base polymer of the paint layer is a polyurethane obtained by a reaction of a polyol with a polyisocyanate, and   the polyol has a weight average molecular weight of 50 or greater and 2,000 or less.   
     
     
         6 . The golf ball according to  claim 1 , wherein the paint layer has a thickness of 5 μm or greater and 40 μm or less. 
     
     
         7 . The golf ball according to  claim 1 , wherein the base polymer of the cover is at least one selected from the group consisting of a polyurethane, an ionomer resin, a polyamide, a polyester, a polystyrene and a polyolefin. 
     
     
         8 . The golf ball according to  claim 1 , wherein the cover has a Shore D hardness of no greater than 55. 
     
     
         9 . The golf ball according to  claim 1 , wherein the cover has a thickness of 0.3 mm or greater and 1.0 mm or less. 
     
     
         10 . The golf ball according to  claim 1 , wherein the amount of compressive deformation of the core is 1.8 mm or greater and 4.0 mm or less as measured under a condition in which the initial load is 98 N and the final load is 1,274 N. 
     
     
         11 . The golf ball according to  claim 1 , wherein
 the core has a center and a mid layer situated on the external side of the center, and   the surface of the center has a JIS-C hardness of 60 or greater and 95 or less.   
     
     
         12 . The golf ball according to  claim 1 , wherein
 the core has a center and a mid layer situated on the external side of the center, and   the amount of compressive deformation of the center is 1.5 mm or greater and 5.0 mm or less as measured under a condition in which the initial load is 98 N and the final load is 1,274 N.   
     
     
         13 . The golf ball according to  claim 1 , wherein
 the core has a center and a mid layer situated on the external side of the center, and   the center has a diameter of 30 mm or greater and 41.5 mm or less.   
     
     
         14 . The golf ball according to  claim 1 , wherein
 the core has a center and a mid layer situated on the external side of the center, and   the center has a weight of 25 g or greater and 42 g or less.   
     
     
         15 . The golf ball according to  claim 1 , wherein
 the core has a center and a mid layer situated on the external side of the center, and   the base polymer of the mid layer is at least one selected from the group consisting of an ionomer resin, a styrene block-containing thermoplastic elastomer, a thermoplastic polyester elastomer, a thermoplastic polyamide elastomer, a thermoplastic polyurethane elastomer and a thermoplastic polyolefin elastomer.   
     
     
         16 . The golf ball according to  claim 1 , wherein
 the core has a center and a mid layer situated on the external side of the center, and   the mid layer has a Shore D hardness of 40 or greater and 75 or less.   
     
     
         17 . The golf ball according to  claim 1 , wherein
 the core has a center and a mid layer situated on the external side of the center, and   the mid layer has a thickness of 0.3 mm or greater and 2.5 mm or less.   
     
     
         18 . The golf ball according to  claim 1  having an amount of compressive deformation of 2.0 mm or greater and 3.5 mm or less as measured under a condition in which the initial load is 98 N and the final load is 1,274 N.