Golf ball

Abstract

A golf ball having a spherical core, a mid layer covering this core, a reinforcing layer covering this mid layer, and a cover covering this reinforcing layer, wherein the base polymer of the mid layer includes a styrene block-containing thermoplastic elastomer and an ionomer resin; the mid layer has a hardness as measured with a Shore D type hardness scale of equal to or less than 54; the mid layer has a thickness of 0.5 mm or greater and 1.6 mm or less; and the base polymer of the reinforcing layer is a reaction product between carboxyl group-containing polyurethane and polycarbodiimide. The principal component of the base polymer of the cover is an ionomer resin. The cover has a hardness as measured with a Shore D type hardness scale hardness of equal to or greater than 55 and the cover has a thickness of equal to or less than 1.2 mm.

1 . A golf ball which comprises a spherical core, amid layer positioned outside of the core, a reinforcing layer positioned outside of the mid layer, and a cover positioned outside of the reinforcing layer,
 said core having a diameter of 39.2 mm or greater and 41.0 mm or less,   said mid layer having (1) a hardness Hm as measured with a Shore D type hardness scale of equal to or less than 54 and (2) a thickness Tm of 0.5 mm or greater and 1.2 mm or less, and   said cover having (1) a hardness Hc as measured with a Shore D type hardness scale of equal to or greater than 56 and (2) a thickness Tc of 0.8 mm or less.   
     
     
         2 . The golf ball according to  claim 1 , wherein said cover has a weight Wc of equal to or less than 4.0 g. 
     
     
         3 . The golf ball according to  claim 1 , wherein said cover has a ratio (Wc/Hc) of the weight Wc to the hardness Hc of equal to or less than 0.080. 
     
     
         4 . The golf ball according to  claim 1 , wherein said mid layer has the hardness Hm of equal to or greater than 30. 
     
     
         5 . The golf ball according to  claim 1 , wherein said cover has the thickness Tc equal to or less than 0.5 mm. 
     
     
         6 . The golf ball according to  claim 1 , wherein said cover has the hardness Hc of equal to or less than 65. 
     
     
         7 . The golf ball according to  claim 1 , wherein said reinforcing layer comprises a water-based adhesive 
     
     
         8 . A golf ball according to  claim 7 , wherein said water-based adhesive comprises a base polymer which is a reaction product between a carboxyl group-containing polyurethane and a polycarbodiimide. 
     
     
         9 . The golf ball according to  claim 1 , wherein said reinforcing layer has a thickness of 0.003 mm or greater and 0.050 mm or less. 
     
     
         10 . The golf ball according to  claim 1 , wherein a base polymer of said reinforcing layer is a reaction product between carboxyl group-containing polyurethane and polycarbodiimide. 
     
     
         11 . The golf ball according to  claim 10 , wherein said carboxyl group-containing polyurethane and said polycarbodiimide are water-based. 
     
     
         12 . The golf ball according to  claim 1 , wherein the principal component of a base polymer of said cover is an ionomer resin. 
     
     
         13 . The golf ball according to  claim 12 , wherein the base polymer of the cover comprises a styrene block-containing thermoplastic elastomer. 
     
     
         14 . The golf ball according to  claim 13 , wherein the base polymer of the cover comprises 10% by weight or less styrene block-containing thermoplastic elastomer. 
     
     
         15 . The golf ball according to  claim 1 , wherein a base polymer of the mid layer comprises 10% by weight or more styrene block-containing thermoplastic elastomer, and 40% by weight or more ionomer resin. 
     
     
         16 . The golf ball according to  claim 15 , wherein the base polymer of the mid layer comprises 10% by weight or more and 60% by weight or less of a styrene block-containing thermoplastic elastomer, and 40% by weight or more and 90% by weight or less of an ionomer resin. 
     
     
         17 . The golf ball according to  claim 16 , wherein the base polymer of the mid layer comprises 30% by weight or more and 60% by weight or less styrene block-containing thermoplastic elastomer, and 40% by weight or more and 70% by weight or less ionomer resin. 
     
     
         18 . The golf ball according to  claim 15 , wherein the styrene block-containing thermoplastic elastomer of the mid layer is an alloy of olefin and one or two or more selected from the group consisting of SBS, SIS, SEBS, SEPS and SEEPS, and hydrogenated products thereof. 
     
     
         19 . The golf ball according to  claim 1 , wherein the golf ball has a diameter greater than 42.67 mm.