Golf ball comprising medium hardness gradient core

Abstract

A golf ball includes a core having an outer surface and a geometric center. The core is formed from a substantially homogenous rubber composition. An ionomeric inner cover layer is formed about the core and has a material hardness of about 60 Shore D or greater. The golf ball includes an outer cover layer formed from a polyurea or a polyurethane and having a material hardness of about 60 Shore D or less. The outer surface of the core has a trans content of about 12% or less and a hardness of about 71 to 88 Shore C. The geometric center of the core has a trans content of about 10% or less and a hardness of about 60 to 80 Shore C. The core has an outer surface hardness greater than a geometric center hardness by about 5 to 19 Shore C to define a positive hardness gradient.

What is claimed is: 
     
         1 . A golf ball comprising:
 a core having an outer surface and a geometric center and being formed from a substantially homogenous rubber composition; and   a cover layer, the outer cover layer comprising a polyurea, a polyurethane, or an ionomer, and having a material hardness of about 60 Shore D or less;   wherein the outer surface has a trans content of about 12% or less and a hardness of about 71 Shore C to 88 Shore C, the geometric center has a trans content of about 10% or less and a hardness of about 60 to 80 Shore C, and the outer surface hardness is greater than the geometric center hardness to define a hardness gradient.   
     
     
         2 . The golf ball of  claim 1 , wherein the outer surface has a trans content of about 10% or less and the geometric center has a trans content of about 8% or less. 
     
     
         3 . The golf ball of  claim 1 , wherein the hardness gradient is about 5 to 19 Shore C. 
     
     
         4 . The golf ball of  claim 3 , wherein the hardness gradient is about 10 to 19 Shore C. 
     
     
         5 . The golf ball of  claim 4 , wherein the hardness gradient is about 12 to 19 Shore C. 
     
     
         6 . The golf ball of claim Error! Reference source not found., wherein the core has an outer diameter of about 1.45 to about 1.62 inches. 
     
     
         7 . The golf ball of  claim 6 , wherein the core has an outer diameter of about 1.50 to about 1.58 inches. 
     
     
         8 . The golf ball of claim Error! Reference source not found., wherein the hardness of the geometric center is about 70 to 80 Shore C. 
     
     
         9 . The golf ball of claim Error! Reference source not found., wherein the hardness of the core surface is about 70 to 74 Shore C. 
     
     
         10 . The golf ball of claim Error! Reference source not found., wherein the outer surface has a trans content of about 10% or less and the geometric center has a trans content of about 8% or less. 
     
     
         11 . A golf ball comprising:
 a core having an outer surface and a geometric center and being formed from a substantially homogenous rubber composition; and   a cover layer, the outer cover layer comprising a thermoplastic polyurethane and having a material hardness of about 60 Shore D or less;   wherein the outer surface has a trans content of about 12% or less and a hardness of about 71 Shore C to 88 Shore C, the geometric center has a trans content of about 10% or less and a hardness of about 60 to 80 Shore C, and the outer surface hardness is greater than the geometric center hardness to define a positive hardness gradient.