Golf Ball Compositions

Abstract

Golf balls consisting of a core and a cover are disclosed. The core is a solid, single-layer core formed from a rubber composition comprising a base rubber, a free radical initiator, and a hydroquinone. A ratio of the amount of the hydroquinone present in the rubber composition, measured in parts by weight, to the amount of free radical initiator present in the rubber composition, measured in parts by weight, is generally from 0.05 to 2. The core has a positive hardness gradient such that the difference between the core's surface hardness and the core's center hardness is 25 Shore C units or greater and/or the core has a diameter of from 1.51 inches to 1.59 inches.

1 . A golf ball consisting of:
 a solid, single-layer core formed from a rubber composition, the rubber composition comprising:
 (a) a base rubber; 
 (b) at least 0.05 parts by weight of a free radical initiator per 100 parts of the base rubber; and 
 (c) at least 0.1 parts by weight of a hydroquinone per 100 parts of the base rubber; 
 wherein a ratio (P HQ /P FRI ) of the amount of the hydroquinone present in the rubber composition (P HQ ), measured in parts by weight per 100 parts of the base rubber, to the amount of free radical initiator present in the rubber composition (P FRI ), measured in parts by weight per 100 parts of the base rubber, is from 0.05 to 2; and 
   a cover;   wherein the core has a center Shore C hardness (H CENTER ) and a surface Shore C hardness (H SURFACE ), and H SURFACE −H CENTER ≧25 Shore C units.   
   
   
       2 . The golf ball of  claim 1 , wherein H SUFACE −H CENTER ≧30 Shore C units. 
   
   
       3 . The golf ball of  claim 1 , wherein H SURFACE −H CENTER ≧35 Shore C units. 
   
   
       4 . The golf ball of  claim 1 , wherein H SURFACE −H CENTER ≧40 Shore C units. 
   
   
       5 . The golf ball of  claim 1 , wherein H SURFACE −H CENTER ≧45 Shore C units. 
   
   
       6 . The golf ball of  claim 1 , wherein the amount of the hydroquinone present in the rubber composition is at least 0.2 parts by weight per 100 parts of the base rubber. 
   
   
       7 . The golf ball of  claim 1 , wherein P HQ /P FRI  is from 0.25 to 0.45. 
   
   
       8 . The golf ball of  claim 1 , wherein the hydroquinone is selected from hydroquinone, tetrachlorohydroquinone, and 2-(2-chlorophenyl)hydroquinone hydrate. 
   
   
       9 . The golf ball of  claim 1 , wherein the rubber composition is substantially free of organosulfur compounds. 
   
   
       10 . A golf ball consisting of:
 a solid, single-layer core having a diameter of from 1.51 inches to 1.59 inches and formed from a rubber composition, the rubber composition comprising:
 (a) a base rubber; 
 (b) at least 0.05 parts by weight of a free radical initiator per 100 parts of the base rubber; and 
 (c) at least 0.1 parts by weight of a hydroquinone per 100 parts of the base rubber; 
   wherein a ratio (P HQ /P FRI ) of the amount of the hydroquinone present in the rubber composition (P HQ ), measured in parts by weight per 100 parts of the base rubber, to the amount of free radical initiator present in the rubber composition (P FRI ), measured in parts by weight per 100 parts of the base rubber, is from 0.05 to 2; and   a cover.   
   
   
       11 . The golf ball of  claim 10 , wherein the core has a center hardness (H CENTER ) of 80 Shore C or less and a surface hardness (H SURFACE ) of greater than 80 Shore C, and wherein H SURFACE −H CENTER ≧25 Shore C units. 
   
   
       12 . The golf ball of  claim 10 , wherein H SURFACE −H CENTER ≧30 Shore C units. 
   
   
       13 . The golf ball of  claim 10 , wherein H SURFACE −H CENTER ≧40 Shore C units. 
   
   
       14 . The golf ball of  claim 10 , wherein H SURFACE −H CENTER ≧45 Shore C units. 
   
   
       15 . The golf ball of  claim 10 , wherein P HQ /P FRI  is from 0.25 to 0.45. 
   
   
       16 . The golf ball of  claim 10 , wherein the hydroquinone is selected from hydroquinone, tetrachlorohydroquinone, and 2-(2-chlorophenyl)hydroquinone hydrate. 
   
   
       17 . The golf ball of  claim 10 , wherein the rubber composition is substantially free of organosulfur compounds.