Golf ball

Abstract

In a golf ball having a core and a cover of at least one layer encasing the core, the core is a product molded under heat from a rubber composition which includes (A) a base rubber, (B) an unsaturated carboxylic acid and/or a metal salt thereof, and (C) an organic peroxide. Letting the content of component (B) in the rubber composition per 100 parts by weight of component (A) be X parts by weight and the concentration of volatile substances from component (B) within the core be A wt %, the value A/X is 0.0123 or less. This golf ball has a low energy loss, enabling a high initial velocity to be obtained.

1 . A golf ball comprising a core and a cover of at least one layer encasing the core, wherein the core is a product molded under heat from a rubber composition comprising (A) a base rubber, (B) an unsaturated carboxylic acid or a metal salt thereof or both, and (C) an organic peroxide; and, letting the content of component (B) in the rubber composition per 100 parts by weight of component (A) be X parts by weight and the concentration of volatile substances from component (B) within the core be A wt %, the value A/X is 0.0123 or less. 
     
     
         2 . The golf ball of  claim 1  wherein dicumyl peroxide is used as component (C) in the rubber composition and, letting the content of component (C) in the rubber composition per 100 parts by weight of component (A) be Y parts by weight and the concentrations of acetophenone and α-cumyl alcohol, which are volatile substances from component (C), within the core be respectively B1 wt % and B2 wt %, the value B1/Y is 0.072 or less and the value B2/Y is 0.270 or less. 
     
     
         3 . The golf ball of  claim 1 , wherein the concentrations of acetophenone and α-cumyl alcohol, which are volatile substances from component (C), are respectively 0.043 wt % or less and 0.15 wt % or less. 
     
     
         4 . The golf ball of  claim 1 , wherein 1,1-di(t-butylperoxy)cyclohexane is used as component (C) in the rubber composition and, letting the content of component (C) in the rubber composition per 100 parts by weight of component (A) be Y parts by weight and the concentration of tert-butanol, which is a volatile substance from component (C), within the core be D wt %, the value D/Y is 0.033 or less. 
     
     
         5 . The golf ball of  claim 1 , wherein the concentration of tert-butanol, which is a volatile substance from component (D), is 0.033 wt % or less. 
     
     
         6 . A golf ball comprising a core and a cover of at least one layer encasing the core, wherein the core is a product molded under heat from a rubber composition comprising (A) a base rubber, (B) an unsaturated carboxylic acid or a metal salt thereof or both, and (C) an organic peroxide; and the concentration of acrylic acid, which is a volatile substance from component (B), within the core is 0.234 wt % or less. 
     
     
         7 . A golf ball comprising a core and a cover of at least one layer encasing the core, wherein the core is a product molded under heat from a rubber composition comprising (A) a base rubber, (B) an unsaturated carboxylic acid or a metal salt thereof or both, and (C) an organic peroxide; and, in thermogravimetric analysis of the core, letting (a) represent the percent weight loss at a center of the core and (b) represent the percent weight loss at a surface of the core, the value (a) is 1.31 wt % or less, the value (b) is 1.37 wt % or less, and the value (a)/(b) is 0.96 or less.