Golf ball having co-injected bi-modal ethylene-acid copolymer dual layer cover

Abstract

A golf ball having a cover comprising thin inner and outer layers formed by a co-injected cup process. The inner layer comprising a hard Surlyn while the outer layer comprises a composition a bi-modal ethylene-acid copolymer composition. The core size will be greater than 1.50 inches in diameter. The golf ball will provide a cover that is compression molded and is very soft without sacrificing durability or shear resistance. The outer layer comprising a bi-modal ethylene-acid co-polymer composition.

1 . A golf ball comprising:
 a core having a diameter equal to or greater than 1.50 inches;   a thin cover formed about the core by co-injection molding, the cover comprising inner and outer layers;   the inner layer of the cover comprising a first material having a first hardness and at least one polymer; and   the outer layer of the cover comprising of a second material having a second hardness that is less than the first, the second material a composition comprising bi-modal ethylene-acid copolymer.   
   
   
       2 . The golf ball of  claim 1 , wherein inner layer is formed from a composition having a molecular weight of about 70,000 or greater and the bi-modal ethylene-acid copolymer outer layer having a molecular weight of about 30,000 or less. 
   
   
       3 . The golf ball of  claim 1 , wherein the bi-modal ionomer is present in an amount of about 10 percent to about 60 percent by weight of the composition. 
   
   
       4 . The golf ball of  claim 1 , wherein the composition of the outer layer further comprises a thermoplastic polymer selected from the group consisting of ionomers, acid copolymers, highly neutralized polymers, and mixtures thereof. 
   
   
       5 . The golf ball of  claim 1 , wherein the inner cover layer has a Shore D hardness of about 40 to 70 and a flexural modulus of about 60,000 psi to about 100,000 psi. 
   
   
       6 . The golf ball of  claim 1 , wherein the outer layer of the cover has a thickness of about 0.02 to 0.045 inch. 
   
   
       7 . The golf ball of  claim 1 , wherein the bi-modal ethylene-acid copolymer has a portion of the acid neutralized. 
   
   
       8 . The golf ball of  claim 7 , wherein the acid of the composition is neutralized by a neutralizing agent comprising barium salts, lithium salts, sodium salts, zinc salts, copper salts, potassium salts, magnesium salts, cesium salts, aluminum salts, tin salts, calcium salts, and mixtures thereof. 
   
   
       9 . The golf ball of  claim 1 , wherein the composition further comprises a processing aid comprising fatty acids, fatty acid salts, and mixtures thereof. 
   
   
       10 . The golf ball of  claim 1 , wherein the first material is comprised of one or more polymers selected from the group consisting of a thermoplastic ionomer, a dynamically vulcanized thermoplastic elastomer, a functionalized styrene-butadiene elastomer, a polyetherester, a polyesterester, a metallocene polymer, a thermoplastic polyetheramide, a thermoplastic polyester, a thermoplastic polyurethane, a ethylene or propylene based polymer, a methyl acrylate, a methyl methacrylate polymer, a polycarbonate, a polyamide, a polyphenylene oxide, a polyether ketone, a polysulfone, a acrylonitrile butadiene polymer, a acrylic styrene-acrylonitrile polymer, a terphthalate polymer, a ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a reinforced polymer, and blends thereof. 
   
   
       11 . The golf ball of  claim 1 , wherein the second material is comprised of one or more polymers selected from the group consisting of a thermoplastic ionomer, a dynamically vulcanized thermoplastic elastomer, a functionalized styrene-butadiene elastomer, a polyetherester, a polyesterester, a metallocene polymer, a thermoplastic polyetheramide, a thermoplastic polyester, a thermoplastic polyurethane, a ethylene or propylene based polymer, a methyl acrylate, a methyl methacrylate polymer, a polycarbonate, a polyamide, a polyphenylene oxide, a polyether ketone, a polysulfone, a acrylonitrile butadiene polymer, a acrylic styrene-acrylonitrile polymer, a terphthalate polymer, a ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a reinforced polymer, and blends thereof. 
   
   
       12 . The golf ball of  claim 1 , further comprising an intermediate layer disposed between the core and the cover, wherein the intermediate layer has a hardness of about 60 Shore D to about 100 Shore D and a flexural modulus of about 60,000 to about 100,000 psi. 
   
   
       13 . A golf ball comprising:
 a core of one or more layers having a diameter equal to or greater than 1.50 inches;   an intermediate layer encased around the core comprising of at least one polymer; hardness of about 60 Shore D to about 75 Shore D and a flexural modulus of about 60,000 to about 100,000 psi.   a cover formed about the core by co-injection molding, the cover comprising inner and outer layers;   the inner layer of the cover comprising having at least one polymer; and   the outer layer of the cover comprising of a polymer and a composition comprising bi-modal ethylene-acid copolymer.   
   
   
       14 . The golf ball of  claim 13 , wherein the intermediate layer comprises a foamed polymer. 
   
   
       15 . The golf ball of  claim 13 , wherein inner layer is formed from a composition having a molecular weight of about 70,000 or greater and the bi-modal ethylene-acid copolymer outer layer having a molecular weight of about 40,000 or less. 
   
   
       16 . The golf ball of  claim 13 , wherein the bi-modal ionomer is present in an amount of about 10 percent to about 80 percent by weight of the composition. 
   
   
       17 . The golf ball of  claim 13 , wherein the composition of the outer layer further comprises a thermoplastic polymer selected from the group consisting of ionomers, acid copolymers, highly neutralized polymers, and mixtures thereof. 
   
   
       18 . The golf ball of  claim 13 , wherein the inner cover layer has a hardness of about 40 Shore D to about 70 Shore D and a flexural modulus of about 60,000 psi to about 100,000 psi. 
   
   
       19 . The golf ball of  claim 13 , wherein the bi-modal ethylene-acid copolymer has a portion of the acid neutralized. 
   
   
       20 . The golf ball of  claim 19 , wherein the acid of the composition is neutralized by a neutralizing agent comprising barium salts, lithium salts, sodium salts, zinc salts, copper salts, potassium salts, magnesium salts, cesium salts, aluminum salts, tin salts, calcium salts, and mixtures thereof. 
   
   
       21 . The golf ball of  claim 20 , wherein the composition further comprises a processing aid comprising fatty acids, fatty acid salts, and mixtures thereof. 
   
   
       22 . The golf ball of  claim 13 , wherein the inner layer of the cover is comprised of one or more polymers selected from the group consisting of a thermoplastic ionomer, a dynamically vulcanized thermoplastic elastomer, a functionalized styrene-butadiene elastomer, a polyetherester, a polyesterester, a metallocene polymer, a thermoplastic polyetheramide, a thermoplastic polyester, a thermoplastic polyurethane, a ethylene or propylene based polymer, a methyl acrylate, a methyl methacrylate polymer, a polycarbonate, a polyamide, a polyphenylene oxide, a polyether ketone, a polysulfone, a acrylonitrile butadiene polymer, a acrylic styrene-acrylonitrile polymer, a terphthalate polymer, a ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a reinforced polymer, and blends thereof. 
   
   
       23 . The golf ball of  claim 13 , wherein the outer layer of the cover is comprised of one or more polymers selected from the group consisting of a thermoplastic ionomer, a dynamically vulcanized thermoplastic elastomer, a functionalized styrene-butadiene elastomer, a polyetherester, a polyesterester, a metallocene polymer, a thermoplastic polyetheramide, a thermoplastic polyester, a thermoplastic polyurethane, a ethylene or propylene based polymer, a methyl acrylate, a methyl methacrylate polymer, a polycarbonate, a polyamide, a polyphenylene oxide, a polyether ketone, a polysulfone, a acrylonitrile butadiene polymer, a acrylic styrene-acrylonitrile polymer, a terphthalate polymer, a ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a reinforced polymer, and blends thereof.