Multilayer golf ball with a thin thermoset outer layer

Abstract

The present invention is directed towards a method of forming a multilayer golf ball which comprises a core, an inner cover layer and an outer cover layer. The steps include forming a golf ball core; molding an inner cover layer around said golf ball core with a material having a first shore D hardness; and casting an outer cover layer around said inner cover layer and golf ball core with a thermoset material having a second shore D hardness less than the first. The core is comprised of a center made from a first rubber based material and an outer layer formed from a second rubber based material. Preferably, the first rubber based material has about 15 to 25 parts of a crosslinking agent per hundred parts of rubber and the second rubber based material has about 20 to 40 parts of a crosslinking agent per hundred parts of rubber.

1 . A golf ball comprising:
 a core comprising:
 a solid center made from a first rubber based material; 
 a solid outer layer made from a second rubber based material having different physical properties from said first rubber based material; 
   a cover comprising:
 an inner cover layer made from an ionomer material having a first shore D hardness and having an outer diameter of at least 1.58 inches; 
 an outer cover layer made from a thermoset material having a second shore D hardness less than the first. 
   
     
     
         2 . The ball of  claim 1  wherein the outer cover layer has a hardness from about 30 shore D to about 60 shore D. 
     
     
         3 . The ball of  claim 2  wherein the outer cover layer has a hardness from about 40 shore D to about 60 shore D. 
     
     
         4 . The ball of  claim 3  wherein the outer cover layer has a hardness from about 50 shore D to about 60 shore D. 
     
     
         5 . The ball of  claim 1  wherein the inner cover layer has a flexural modulus of about 65,000 psi or more. 
     
     
         6 . The ball of  claim 5  wherein the inner cover layer has a hardness from about 65 shore D to about 74 shore D. 
     
     
         7 . The ball of  claim 6  wherein the inner cover layer has a hardness from about 68 shore D to about 72 shore D. 
     
     
         8 . The ball of  claim 1  wherein the outer diameter of the inner cover layer is from about 1.6 inches to about 1.63 inches. 
     
     
         9 . The ball of  claim 8  wherein the outer diameter of the inner cover layer is from about 1.62 inches to about 1.63 inches. 
     
     
         10 . The ball of  claim 1  wherein the center has an outer diameter from about 0.75 inches to about 1.3 inches. 
     
     
         11 . The ball of  claim 10  wherein the center has an outer diameter from about 1 inch to about 1.15 inches. 
     
     
         12 . The ball of  claim 1  wherein the outer diameter of the core outer layer is from about 1.55 inches to about 1.58 inches. 
     
     
         13 . The ball of  claim 1  wherein the core outer layer has a first crosslinking agent in an amount from about 20 to about 40 parts per hundred of rubber. 
     
     
         14 . The ball of  claim 13  wherein the amount of first crosslinking agent in the core outer layer is from about 30 to about 38 parts per hundred of rubber. 
     
     
         15 . The ball of  claim 13  wherein the core outer layer has from about 10 to about 17 parts of balata per hundred parts of rubber. 
     
     
         16 . The ball of  claim 1  wherein the center has a second crosslinking agent in an amount from about 15 to about 25 parts per hundred of rubber. 
     
     
         17 . The ball of  claim 16  wherein the amount of second crosslinking agent in the center is from about 19 to about 25 parts per hundred of rubber. 
     
     
         18 . A golf ball comprising:
 a core comprising:
 a solid center made from a first rubber based material; 
 a solid outer layer made from a second rubber based material having different physical properties from said first rubber based material; 
   a cover comprising an inner cover layer made from a material having a first shore D hardness from about 65 shore D to about 74 shore D and having an outer diameter of at least 1.6 inches;   an outer cover layer made from a thermoset material having a second shore D hardness less than the first.   
     
     
         19 . The ball of  claim 18  wherein the outer cover layer has a hardness of from about 30 shore D to about 60 shore D. 
     
     
         20 . The ball of  claim 19  wherein the inner cover layer material has a hardness from about 68 shore D to about 72 shore D. 
     
     
         21 . The ball of  claim 20  wherein the outer cover layer has a hardness from about 40 shore D to about 60 shore D. 
     
     
         22 . The ball of  claim 21  wherein the hardness of the outer cover layer is from about 50 shore D to about 60 shore D.