Golf Balls Including Highly Neutralized Polymer Having a Hardness Modifier

Abstract

A golf ball includes a core made from a highly neutralized polymer that has been mixed with a hardness modifier. The modifier may be a process oil or a plasticizer. In particular, the modifier may be a naphthenic process oil, a paraffinic process oil, a phthalate plasticizer, a trimellitate plasticizer, an adipate plasticizer, a sebacate-based plasticizer, a maleate-based plasticizer, and blends thereof. Also disclosed is a method for manufacturing a golf ball that includes changing the hardness of a highly neutralized polymer core.

What is claimed is: 
     
         1 . A golf ball, comprising:
 a core;   a cover layer substantially surrounding the core;   at least one of the core and the cover layer being made of a polymer mixture comprising a polymer and a modifier, wherein the polymer comprises a highly neutralized polymer and the modifier is selected from the group consisting of plasticizers and combinations thereof;   wherein the modifier is present in the polymer mixture in a sufficient amount such that the modifier reduces a hardness of the polymer mixture from a first value that is approximately the same as a hardness of the highly neutralized polymer to a second value that is less than the hardness of the highly neutralized polymer.   
     
     
         2 . The golf ball of  claim 1 , wherein the modifier comprises a plasticizer selected from the group consisting of phthalate esters, trimellitates, adipates, sebacate-based plasticizer, maleate-based plasticizer, and combinations thereof. 
     
     
         3 . The golf ball of  claim 1 , wherein the modifier is di-isononyl phthalate. 
     
     
         4 . The golf ball of  claim 1 , wherein the modifier is present in the polymer mixture in an amount of from about 1 to about 25 parts by weight per 100 parts by weight of polymer. 
     
     
         5 . The golf ball of  claim 1 , wherein the second value is at least about 3 Shore D less than the first value. 
     
     
         6 . The golf ball of  claim 1 , wherein the polymer mixture further comprises a compatibilizer selected from the group consisting of maleic anhydride, silanes, titanates, and blends thereof. 
     
     
         7 . The golf ball of  claim 1 , wherein the cover layer comprises the polymer mixture, and the polymer mixture further comprises a compatibilizer selected from the group consisting of maleic anhydride, silanes, titanates, and blends thereof. 
     
     
         8 . The golf ball of  claim 1 , wherein the core comprises the polymer mixture; and the presence of the modifier reduces a COR value of the core by a proportion that is less than a proportion by which the presence of the modifier causes the polymer mixture to have a lower hardness than the hardness of the highly neutralized polymer. 
     
     
         9 . A golf ball comprising:
 an inner core;   an outer core layer substantially surrounding the inner core; and   at least one cover layer substantially surrounding the outer core layer;   wherein at least one of the inner core and the outer core layer comprises a polymer mixture comprising a polymer and a modifier, wherein the polymer comprises a highly neutralized polymer and the modifier is selected from the group consisting of phthalate esters, trimellitates, adipates, sebacate-based plasticizer, maleate-based plasticizer, and combinations thereof;   wherein the modifier is present in the polymer mixture in an amount of from about 1 to about 25 parts by weight per 100 parts by weight of polymer; and   wherein the modifier is present in the polymer mixture in a sufficient amount such that the modifier reduces a hardness of the polymer mixture from a first value that is approximately the same as a hardness of the highly neutralized polymer to a second value that is less than the hardness of the highly neutralized polymer, the second value being at least about 2 Shore D less than the first value.   
     
     
         10 . The golf ball of  claim 9 , wherein the modifier is di-isononyl phthalate. 
     
     
         11 . The golf ball of  claim 9 , wherein the inner core comprises the polymer mixture; the presence of the modifier in the polymer material reduces a COR value of the inner core by less than 5%; and the presence of the modifier in the polymer mixture reduces the hardness of the polymer mixture by more than 5%. 
     
     
         12 . The golf ball of  claim 9 , wherein the inner core has a diameter of from about 20 to about 30 mm, and the outer core layer has a thickness of from about 3 to about 10 mm. 
     
     
         13 . The golf ball of  claim 9 , wherein the polymer consists essentially of a mixture of two types of highly neutralized polymers. 
     
     
         14 . The golf ball of  claim 10 , wherein the polymer comprises a blend of the highly neutralized polymer and at least one additional polymer, the at least one additional polymer being a type of polymer other than a highly neutralized polymer. 
     
     
         15 . A method of manufacturing a golf ball, comprising:
 forming a core from a polymer mixture comprising a highly neutralized polymer and a modifier selected from the group consisting of plasticizers and combinations thereof and   forming a cover layer around the core;   wherein the modifier reduces a hardness of the polymer mixture from a first value that is the hardness of the highly neutralized polymer to a second value that is less than the hardness of the highly neutralized polymer, wherein the reduction in hardness is of a first proportion; and   the presence of the modifier reduces the COR value of the core by a second proportion that is less than the first proportion.   
     
     
         16 . The method of  claim 15 , wherein the modifier is selected from the group consisting of phthalate esters, trimellitates, adipates, sebacate-based plasticizer, maleate-based plasticizer, and combinations thereof. 
     
     
         17 . The method of  claim 15 , wherein the modifier is present in the polymer mixture in an amount of from about 1 to about 25 parts by weight per 100 parts by weight of highly neutralized polymer. 
     
     
         18 . The method of  claim 15 , wherein a ratio of the first proportion to the second proportion is greater than about 2:1. 
     
     
         19 . The method of  claim 15 , wherein the first proportion is at least about 10%, and the second proportion is at most about 5%.