Golf ball

Abstract

An object of the present disclosure is to provide a golf ball that shows a low initial velocity on approach shots, has excellent controllability, and has a good shot feeling on approach shots. The present disclosure provides a golf ball comprising a spherical core, an intermediate layer and a cover, wherein the spherical core is formed from a rubber composition containing a rubber component, a co-crosslinking agent, and a crosslinking initiator, the co-crosslinking agent contains methacrylic acid and/or a metal salt thereof, and when a center hardness (Shore C hardness) of the spherical core, a hardness (Shore C hardness) at each point of 2.5 mm, 5 mm, 7.5 mm, 10 mm, 12.5 mm and 15 mm from a center of the spherical core toward a surface of the spherical core, and a surface hardness (Shore C hardness) of the spherical core are represented by H0, H2.5, H5, H7.5, H10, H12.5, H15, HS respectively, the following relationship is satisfied: H0<H2.5<H5<H7.5<H10<H12.5<H15<HS.

1 . A golf ball comprising a spherical core, at least one intermediate layer positioned outside the spherical core, and a cover positioned outside the intermediate layer, wherein
 the spherical core is formed from a rubber composition containing a rubber component, a co-crosslinking agent, and a crosslinking initiator,   the co-crosslinking agent contains methacrylic acid and/or a metal salt thereof, and   when a center hardness (Shore C hardness) of the spherical core, a hardness (Shore C hardness) at each point of 2.5 mm, 5 mm, 7.5 mm, 10 mm, 12.5 mm and 15 mm from a center of the spherical core toward a surface of the spherical core, and a surface hardness (Shore C hardness) of the spherical core are represented by H 0 , H 2.5 , H 5 , H 7.5 , H 10 , H 12.5 , H 15 , H S  respectively, the following relationship is satisfied: H 0 <H 2.5 <H 5 <H 7.5 <H 10 <H 12.5 <H 15 <H S .   
     
     
         2 . The golf ball according to  claim 1 , wherein each of (H 2.5 −H 0 ), (H 5 −H 2.5 ), (H 7.5 −H 5 ), (H 10 −H 7.5 ), (H 12.5 −H 10 ), (H 15 −H 12.5 ), and (H S −H 15 ) is 5 or less. 
     
     
         3 . The golf ball according to  claim 1 , wherein (H S −H 0 ) is 20 or less. 
     
     
         4 . The golf ball according to  claim 1 , wherein the surface hardness H S  of the spherical core is 80 or less in Shore C hardness, and the center hardness H 0  of the spherical core is 60 or less in Shore C hardness. 
     
     
         5 . The golf ball according to  claim 1 , wherein a material hardness Hm of the intermediate layer is greater than a material hardness Hc of the cover. 
     
     
         6 . The golf ball according to  claim 1 , wherein the intermediate layer has a material hardness Hm of 50 or more in Shore D hardness. 
     
     
         7 . The golf ball according to  claim 1 , wherein the cover has a material hardness Hc of 40 or less in Shore D hardness. 
     
     
         8 . The golf ball according to  claim 1 , wherein the rubber component includes a mixture of a polybutadiene rubber and a butyl rubber and/or an isoprene rubber. 
     
     
         9 . The golf ball according to  claim 1 , wherein the intermediate layer contains an ionomer resin as a resin component. 
     
     
         10 . The golf ball according to  claim 1 , wherein the cover contains a polyurethane as a resin component. 
     
     
         11 . The golf ball according to  claim 2 , wherein each of (H 2.5 −H 0 ), (H 5 −H 2.5 ), (H 7.5 −H 5 ), (H 10 −H 7.5 ), (H 12.5 −H 10 ), (H 15 −H 12.5 ), and (H S −H 15 ) is 0 or more and 5 or less. 
     
     
         12 . The golf ball according to  claim 3 , wherein (H S −H 0 ) is 5 or more and 20 or less. 
     
     
         13 . The golf ball according to  claim 8 , wherein a mass ratio [polybutadiene rubber/(butyl rubber and/or polyisoprene rubber)] of the polybutadiene rubber to the butyl rubber and/or the polyisoprene rubber ranges from 30/70 to 95/5. 
     
     
         14 . The golf ball according to  claim 1 , wherein the co-crosslinking agent contains methacrylic acid and/or the metal salt thereof in an amount of 50 mass % or more. 
     
     
         15 . The golf ball according to  claim 1 , wherein the co-crosslinking agent consists of methacrylic acid and/or the metal salt thereof.