Golf ball

Abstract

An object of the present disclosure is to provide a golf ball that has a low maximum flying height on driver shots by an average golfer. The present disclosure provides a golf ball comprising a spherical core, an intermediate layer and an outermost 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, a total lower volume Vi (mm 3 ) of the plurality of dimples is 365 mm 3 or more, and an occupation ratio of the dimples is 75% or more.

1 . A golf ball comprising a spherical core, at least one intermediate layer positioned outside the spherical core, and an outermost cover positioned outside the intermediate layer and having a plurality of dimples formed thereon, 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,   a total lower volume Vi (mm 3 ) of the plurality of dimples is 365 mm 3  or more, and   an occupation ratio of the dimples defined by the following formula is 75% or more;
   Occupation ratio (%) of dimples=100×total area of all dimples/surface area of a virtual sphere that is assumed to have no dimples on golf ball surface.
 
   
     
     
         2 . The golf ball according to  claim 1 , wherein the total lower volume Vi (mm 3 ) is 400 mm 3  or more. 
     
     
         3 . The golf ball according to  claim 1 , wherein 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 relationships (1) to (7) are satisfied;
   ( H   2.5   −H   0 )≤5  (1),
     ( H   5   −H   2.5 )≤5  (2),
     ( H   7.5   −H   5 )≤5  (3),
     ( H   10   −H   7.5 )≤5  (4),
     ( H   12.5   −H   10 )≤5  (5),
     ( H   15   −H   12.5 )≤5  (6), and
     ( H   S   −H   15 )≤5  (7).
   
     
     
         4 . The golf ball according to  claim 1 , wherein (H S −H 0 ) is 20 or less in Shore C hardness. 
     
     
         5 . The golf ball according to  claim 1 , wherein the spherical core has a surface hardness H S  of 80 or less in Shore C hardness, and a center hardness H 0  of 60 or less in Shore C hardness. 
     
     
         6 . 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. 
     
     
         7 . The golf ball according to  claim 1 , wherein the intermediate layer has a material hardness Hm of 60 or more in Shore D hardness. 
     
     
         8 . The golf ball according to  claim 1 , wherein the cover has a material hardness Hc of 40 or less in Shore D hardness. 
     
     
         9 . 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. 
     
     
         10 . The golf ball according to  claim 1 , wherein the intermediate layer contains an ionomer resin as a resin component. 
     
     
         11 . The golf ball according to  claim 1 , wherein the cover contains a polyurethane as a resin component. 
     
     
         12 . The golf ball according to  claim 3 , wherein (H S −H 0 ) is 5 or more and 20 or less in Shore C hardness. 
     
     
         13 . The golf ball according to  claim 9 , wherein a mass ratio [the polybutadiene rubber/(the butyl rubber and/or the 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.