Multi-layer golf ball

Abstract

Multi-layer golf balls comprising a single- or dual-layer core, an intermediate layer, and an outer cover layer are disclosed. The intermediate layer is formed from a highly neutralized polymer composition and has a surface hardness which is greater than the center hardness of the core and less than the outer surface hardness of the core. The outer surface hardness of the outer cover layer is greater than the outer surface hardness of the core.

What is claimed is: 
     
         1 . A three-layer golf ball having a compression of from 30 to 90 and consisting essentially of:
 a center having a diameter of from 1.25 inches to 1.55 inches, a center Shore C hardness (H center ) of from 45 to 70, an outer surface Shore C hardness (H core surface ) of from 80 to 95, and formed from a rubber composition;   an intermediate layer having an outer surface Shore C hardness (H intermediate surface ) of from 55 to 80, a thickness of from 0.020 inches to 0.120 inches, and formed from a highly neutralized polymer composition having a material hardness of from 50 Shore C to 80 Shore C and comprising the reaction product of:
 an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid, optionally including a softening monomer selected from the group consisting of alkyl acrylates and methacrylates; 
 a non-acid polymer selected from the group consisting of polyolefins, polyamides, polyesters, polyethers, polyurethanes, metallocene-catalyzed polymers, single-site catalyst polymerized polymers, ethylene propylene rubber, ethylene propylene diene rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers, and functionalized derivatives thereof; 
 a cation source; and 
 optionally, an organic acid or salt thereof; 
 wherein the acid copolymer is present in an amount of from 20 wt % to 90 wt % and the non-acid polymer is present in an amount of from 10 wt % to 80 wt %, based on the combined weight of the acid copolymer and the non-acid polymer; and 
 wherein greater than 70% of all acid groups present in the highly neutralized polymer composition are neutralized; and 
   an outer cover layer having an outer surface Shore C hardness (H outer cover surface ) of from 82 to 99 and a thickness of from 0.020 inches to 0.080 inches;   wherein H center <H intermediate surface <H core surface <H outer cover surface ; and   wherein the difference between H core surface  and H intermediate surface  is from 5 to 30.   
     
     
         2 . The golf ball of  claim 1 , wherein the non-acid polymer of the highly neutralized polymer composition of the intermediate layer is a maleic anhydride-modified polyolefin. 
     
     
         3 . The golf ball of  claim 1 , wherein the compression of the golf ball is from 40 to 80. 
     
     
         4 . The golf ball of  claim 1 , wherein the compression of the golf ball is from 50 to 75. 
     
     
         5 . The golf ball of  claim 1 , wherein the highly neutralized polymer composition of the intermediate layer has a solid sphere compression of from −50 to 50. 
     
     
         6 . The golf ball of  claim 1 , wherein the ratio of the overall ball compression to the solid sphere compression of the highly neutralized polymer composition of the intermediate layer is <1.00. 
     
     
         7 . The golf ball of  claim 1 , wherein the outer cover layer is formed from a composition selected from ionomers, polyurethanes, polyureas, and blends thereof. 
     
     
         8 . The golf ball of  claim 7 , wherein the outer cover layer composition has a solid sphere compression of from 80 to 180. 
     
     
         9 . The golf ball of  claim 1 , wherein the intermediate layer has a thickness of from 0.030 inches to 0.060 inches. 
     
     
         10 . The golf ball of  claim 1 , wherein the difference between H core surface  and H intermediate surface  is from 10 to 25. 
     
     
         11 . A four-layer golf ball having a compression of from 30 to 90 and consisting essentially of:
 a dual core having an outer diameter of from 1.25 inches to 1.55 inches, a center Shore C hardness (H center ) of from 45 to 70, an outer surface Shore C hardness (H core surface ) of from 80 to 95, and consisting of a center formed from a first rubber composition and an outer core layer formed from a second rubber composition;   an intermediate layer having an outer surface Shore C hardness (H intermediate surface ) of from 55 to 80, a thickness of from 0.020 inches to 0.120 inches, and formed from a highly neutralized polymer composition having a material hardness of from 50 Shore C to 80 Shore C and comprising the reaction product of:
 an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid, optionally including a softening monomer selected from the group consisting of alkyl acrylates and methacrylates; 
 a non-acid polymer selected from the group consisting of polyolefins, polyamides, polyesters, polyethers, polyurethanes, metallocene-catalyzed polymers, single-site catalyst polymerized polymers, ethylene propylene rubber, ethylene propylene diene rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers, and functionalized derivatives thereof; 
 a cation source; and 
 optionally, an organic acid or salt thereof; 
 wherein the acid copolymer is present in an amount of from 20 wt % to 90 wt % and the non-acid polymer is present in an amount of from 10 wt % to 80 wt %, based on the combined weight of the acid copolymer and the non-acid polymer; and 
 wherein greater than 70% of all acid groups present in the highly neutralized polymer composition are neutralized; and 
   an outer cover layer having an outer surface Shore C hardness (H outer cover surface ) of from 82 to 99 and a thickness of from 0.020 inches to 0.080 inches;   wherein H center <H intermediate surface <H core surface <H outer cover surface ; and   wherein the difference between H core surface  and H intermediate surface  is from 5 to 30.   
     
     
         12 . The golf ball of  claim 11 , wherein the non-acid polymer of the highly neutralized polymer composition of the intermediate layer is a maleic anhydride-modified polyolefin. 
     
     
         13 . The golf ball of  claim 11 , wherein the compression of the golf ball is from 40 to 80. 
     
     
         14 . The golf ball of  claim 11 , wherein the compression of the golf ball is from 50 to 75. 
     
     
         15 . The golf ball of  claim 11 , wherein the highly neutralized polymer composition of the intermediate layer has a solid sphere compression of from −50 to 50. 
     
     
         16 . The golf ball of  claim 11 , wherein the ratio of the overall ball compression to the solid sphere compression of the highly neutralized polymer composition of the intermediate layer is <1.00. 
     
     
         17 . The golf ball of  claim 11 , wherein the outer cover layer is formed from a composition selected from ionomers, polyurethanes, polyureas, and blends thereof. 
     
     
         18 . The golf ball of  claim 17 , wherein the outer cover layer composition has a solid sphere compression of from 80 to 180. 
     
     
         19 . The golf ball of  claim 11 , wherein the intermediate layer has a thickness of from 0.030 inches to 0.060 inches. 
     
     
         20 . The golf ball of  claim 11 , wherein the difference between H core surface  and H intermediate surface  is from 10 to 25.