Golf ball

Abstract

An object of the present invention is to provide a golf ball traveling a great flight distance on driver shots. The present invention provides a golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a specific organic peroxide, and (d) a carboxylic acid and/or a salt thereof, provided that the rubber composition further contains (e) a metal compound in the case of containing only (b) the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.

1 . A golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) an organic peroxide represented by a following formula (1), and (d) a carboxylic acid and/or a salt thereof, provided that the rubber composition further contains (e) a metal compound in the case of containing only (b) the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent. 
       
         
           
           
               
               
           
         
         [In the formula (1), R 1  to R 10  each represent a hydrogen atom, alkyl group, aryl group, aralkyl group, or alkylaryl group independently, wherein the alkyl group, aryl group, aralkyl group, or alkylaryl group may be bonded via an ester group.] 
       
     
     
         2 . The golf ball according to  claim 1 , wherein the rubber composition contains (d) the carboxylic acid and/or the salt thereof in a content ranging from 0.5 part to 40 parts by mass with respect to 100 parts by mass of (a) the base rubber. 
     
     
         3 . The golf ball according to  claim 1 , wherein (d) the carboxylic acid and/or the salt thereof includes an aliphatic carboxylic acid and/or a salt thereof. 
     
     
         4 . The golf ball according to  claim 3 , wherein the aliphatic carboxylic acid and/or the salt thereof has 1 to 30 carbon atoms. 
     
     
         5 . The golf ball according to  claim 1 , wherein (d) the carboxylic acid and/or the salt thereof includes an aromatic carboxylic acid and/or a salt thereof. 
     
     
         6 . The golf ball according to  claim 5 , wherein the aromatic carboxylic acid and/or the salt thereof includes a carboxylic acid having a benzene ring and/or a salt thereof. 
     
     
         7 . The golf ball according to  claim 1 , wherein R 1 , R 5 , R 6  and R 19  each represent an alkyl group having 1 to 11 carbon atoms independently, and R 2  to R 4  and R 7  to R 9  each represent an aryl group or an alkyl group having 1 to 11 carbon atoms independently. 
     
     
         8 . The golf ball according to  claim 1 , wherein (c) the organic peroxide includes 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3. 
     
     
         9 . The golf ball according to  claim 1 , wherein the rubber composition further comprises (f) an organic sulfur compound. 
     
     
         10 . The golf ball according to  claim 9 , wherein (f) the organic sulfur compound is at least one selected from the group consisting of thiophenols and/or metal salts thereof, thionaphthols and/or metal salts thereof, diphenylpolysulfides, and thiuram disulfides. 
     
     
         11 . The golf ball according to  claim 9 , wherein (f) the organic sulfur compound is at least one selected from the group consisting of thiophenols substituted with halogen, metal salts of the thiophenols substituted with halogen, and diphenyldisulfides substituted with halogen. 
     
     
         12 . The golf ball according to  claim 9 , wherein (f) the organic sulfur compound is at least one selected from the group consisting of 2,6-dichlorothiophenol, a metal salt of 2,6-dichlorothiophenol, pentachlorothiophenol, a metal salt of pentachlorothiophenol, pentabromothiophenol, a metal salt of pentabromothiophenol, bis(pentabromophenyl)disulfide, bis(2,6-dichlorophenyl)disulfide, bis(pentachlorophenyl)disulfide, 2-thionaphthol and a metal salt of 2-thionaphthol. 
     
     
         13 . The golf ball according to  claim 9 , wherein the rubber composition contains (f) the organic sulfur compound in a content ranging from 0.05 part to 5 parts by mass with respect to 100 parts by mass of (a) the base rubber. 
     
     
         14 . The golf ball according to  claim 1 , wherein the rubber composition contains (b) the metal salt of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms. 
     
     
         15 . The golf ball according to  claim 1 , wherein the rubber composition contains (b) the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or the metal salt thereof in a content ranging from 15 parts to 50 parts by mass with respect to 100 parts by mass of (a) the base rubber. 
     
     
         16 . The golf ball according to  claim 1 , wherein the spherical core has a hardness difference (Hs-Ho) between a surface hardness (Hs) thereof and a center hardness (Ho) thereof of 12 or more in JIS-C hardness. 
     
     
         17 . The golf ball according to  claim 1 , wherein the spherical core has a center hardness (Ho) in a range from 30 to 70 in JIS-C hardness. 
     
     
         18 . The golf ball according to  claim 1 , wherein the spherical core has a surface hardness (Hs) in a range from 65 to 100 in JIS-C hardness. 
     
     
         19 . The golf ball according to  claim 1 , wherein the spherical core has a compression deformation amount ranging from 2.0 mm to 6.0 mm, when applying a load from an initial load of 98N to a final load of 1275N to the spherical core having a diameter in a range from 34.8 mm to 42.2 mm. 
     
     
         20 . The golf ball according to  claim 1 , wherein (a) the base rubber includes a polybutadiene having a molecular weight distribution MW/MN (MW: weight-average molecular weight, MN: number-average molecular weight) in a range from 2.0 to 6.0.