Golf ball cover compositions

Abstract

The present invention is directed to a novel golf ball cover composition comprised of a blend of a new metal cation neutralized high acid ionomer resin and an ionomer resin containing an additional comonomer of the acrylate ester class. When the new ionomer resin blend is utilized to manufacture a golf ball, the golf ball produced thereby exhibits an improved combination of distance, playability, and/or durability properties.

I claim:  
     
         1 . A golf ball having a cover, wherein the cover comprises a blend of 80-50% by weight of a high stiffness ionomer and 20-50% by weight of a very low modulus ionomer, wherein said high stiffness ionomer is a copolymer of 75-80% of an olefin with 20-25% of an alpha, beta ethylenically unsaturated carboxylic acid having 10-90% of the carboxylic acid groups neutralized with sodium, lithium, zinc or magnesium ions and has flexural modulus from about 75,000 to about 88,000 psi and a Shore D hardness from about 67 to about 77 and the very low modulus ionomer is a terpolymer of 67-70% by weight ethylene, 20-23% by weight acrylate and 10% by weight unsaturated carboxylic acid, where 10-90% of the acid groups are neutralized by sodium, zinc or lithium ions and has a flexural modulus from about 2,000 to 8,000 psi and a Shore D hardness from about 20 to about 45.  
     
     
         2 . The golf ball of    claim 1    wherein the unsaturated carboxylic acid is selected from the group consisting of methacrylic acid, acrylic acid and mixtures of said acids.  
     
     
         3 . The golf ball of    claim 1    wherein the cover comprises 70% by weight of the high stiffness ionomer and 30% by weight of the very low modulus ionomer.  
     
     
         4 . The golf ball of    claim 1    wherein the cover comprises 50% by weight of the high stiffness ionomer and 50% by weight of the very low modulus ionomer.  
     
     
         5 . The golf ball of    claim 1    wherein the cover further comprises colorant in amounts up to 5 parts per hundred polymer.  
     
     
         6 . A composition suitable for molding a golf ball cover comprising 80-50% by weight of a high stiffness ionomer and 20-50% by weight of a very low modulus ionomer, wherein said high stiffness ionomer is a copolymer of 75-80% of an olefin with 20-25% of an alpha, beta ethylenically unsaturated carboxylic acid having 10-90% of the carboxylic acid groups neutralized with sodium, lithium, zinc or magnesium ions and has a flexural modulus from about 75,000 to about 88,000 psi and a Shore D hardness of from about 67 to about 77 and the very low modulus ionomer is a terpolymer of 67-70% by weight ethylene, 20-23% by weight acrylate and 10% by weight unsaturated carboxylic acid, where 10-90% of the acid groups are neutralized by sodium, zinc or lithium ions and has a flexural modulus from about 2,000 to 8,000 psi and a Shore D hardness of from about 20 to about 45.  
     
     
         7 . The composition of    claim 6    wherein the unsaturated carboxylic acid is selected from the group consisting of methacrylic acid, acrylic acid and mixtures of said acids.  
     
     
         8 . The composition of    claim 6    comprising 70% by weight of the high stiffness ionomer and 30% by weight of the very low modulus ionomer.  
     
     
         9 . The composition of    claim 6    comprising 50% by weight of the high stiffness ionomer and 50% by weight of the very low modulus ionomer.  
     
     
         10 . A method of making a golf ball comprising preparing a cover of a blend of 80-50% by weight of a high stiffness ionomer and 20-50% by weight of a very low modulus ionomer, wherein said high stiffness ionomer is a copolymer of 75-80% of an olefin with 20-25% of an alpha beta ethylenically unsaturated carboxylic acid having 10-90% of the carboxylic acid groups neutralized with sodium, lithium, zinc or magnesium ions and has a flexural modulus from about 75,000 to about 88,000 psi and a Shore D hardness of from about 67 to about 77 and the very low modulus ionomer is a terpolymer of 67-70% by weight ethylene, 20-23% by weight acrylate and 10% by weight carboxylic acid, where 10-90% of the acid groups are neutralized by sodium, zinc or lithium ions and has a flexural modulus from about 2,000 to 8,000 psi and a Shore D hardness of from about 20 to about 45.  
     
     
         11 . The method of    claim 10    wherein in the preparation of the cover the unsaturated carboxylic acid is selected from the group consisting of methacrylic acid, acrylic acid, and mixtures of said acids.  
     
     
         12 . The method of    claim 10    wherein in the preparation of the cover, the blend comprises 70% by weight of the high stiffness ionomer and 30% by weight of the very low modulus ionomer.  
     
     
         13 . The method of    claim 10    wherein in the preparation of the cover, the blend comprises 50% by weight of the high stiffness ionomer and 50% by weight of the very low modulus ionomer.  
     
     
         14 . A golf ball having a cover, wherein the cover comprises a blend of 90% -10% by weight of a high stiffness ionomer and 10% to 90% by weight of a very low modulus ionomer, wherein said high stiffness ionomer is a copolymer of less than 84% of an olefin with greater than 16% of an alpha, beta ethylenically unsaturated carboxylic acid having 10-90% of the carboxylic acid groups neutralized with sodium, lithium, zinc or magnesium ions and has a Shore D hardness of 70 or greater and the very low modulus ionomer is a terpolymer of 40-85% by weight ethylene, 10-40% by weight acrylate and 2-20% by weight unsaturated carboxylic acid where 10-90% by weight of the acid groups are neutralized by sodium, zinc, or lithium ions and has a flexural modulus from about 1,500 to 15,000 psi and a Shore D hardness of 20-45.