Golf ball

Abstract

A golf ball includes, as a constituent element thereof, a molded and crosslinked product obtained from a rubber composition containing (A) a base rubber which includes a polybutadiene having a cis-1,4 bond content of at least 60 wt %, (B) an unsaturated carboxylic acid and/or a metal salt thereof, (C) an organosulfur compound, (D) one or more organic peroxide selected from the group consisting of peroxyketals and/or dialkyl peroxides, and (E) one or more organic peroxide selected from the group consisting of hydroperoxides. In the golf ball, the value obtained by subtracting a center hardness of the molded and crosslinked product from a surface hardness thereof, expressed as the JIS-C hardness, is at least 20. The golf ball has a reduced spin rate on shots with a driver and therefore is able to follow a reliable trajectory that does not tend to dip or to rise in a high arc, enabling an increased distance to be achieved.

1 . A golf ball comprising a molded and crosslinked product obtained from a rubber composition comprised of components A to E below:
 (A) a base rubber which includes a polybutadiene having a cis-1,4 bond content of at least 60 wt %;   (B) an unsaturated carboxylic acid and/or a metal salt thereof;   (C) an organosulfur compound;   (D) one or more organic peroxide selected from the group consisting of peroxyketals and/or dialkyl peroxides; and   (E) one or more organic peroxide selected from the group consisting of hydroperoxides,   
       wherein the value obtained by subtracting a center hardness of the molded and crosslinked product from a surface hardness thereof, expressed as the JIS-C hardness, is at least 20. 
     
     
         2 . The golf ball of  claim 1 , wherein the peroxyketal of component D is one or more selected from the group consisting of 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 1,1-di(t-butylperoxy)-2-methylcyclohexane, 2,2-di(t-butylperoxy)butane, n-butyl-4,4-di(t-butylperoxy)valerate and 2,2-di(4,4-di(t-butylperoxy)cyclohexyl)propane. 
     
     
         3 . The golf ball of  claim 1 , wherein the dialkylperoxide of component D is one or more selected from the group consisting of di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-hexyl peroxide, di-t-butyl peroxide and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne. 
     
     
         4 . The golf ball of  claim 1 , wherein the hydroperoxide of component E is one or more selected from the group consisting of p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide and t-butyl hydroperoxide. 
     
     
         5 . The golf ball of  claim 1 , wherein the rubber composition includes, per 100 parts by weight of component A: from 10 to 60 parts by weight of component B, from 0.1 to 5 parts by weight of component C, from 0.25 to 8 parts by weight of component D, and from 0.05 to 5 parts by weight of component E.