Golf Balls Having Multi-Layered Covers Based On Aromatic and Aliphatic Polyurethanes

Abstract

Golf balls having multi-layered covers are provided. The cover includes an inner cover layer made of an ionomer composition; an intermediate cover layer made of an aromatic polyurethane composition; and outer cover layer made of an aliphatic polyurethane composition, wherein the total thickness of the multi-layered cover is no greater than 0.110 inches. Preferably, the thickness of the inner cover layer is 0.010 to 0.050 inches; the thickness of the intermediate cover layer is 0.010 to 0.040 inches; and thickness of the outer cover layer is 0.004 to 0.020 inches. The invention also includes methods for making such multi-layered covers. The resulting ball has good light-stability, cut/shear-resistance, and impact durability.

We claim: 
     
         1 . A golf ball, comprising:
 a core, and   a multi-layered cover having three layers, the multi-layered cover comprising:
 i) an inner cover layer comprising an ionomer composition containing ethylene acid copolymer having acid groups such that at least 30% of the acid groups are neutralized, the ethylene acid copolymer being present in an amount of at least 75 weight percent; 
 ii) an outer cover layer comprising a first polyurethane composition containing aliphatic polyurethane, the aliphatic polyurethane being present in an amount of at least 75 weight percent; and 
 iii) an intermediate cover layer disposed between the inner cover layer and outer cover layer, the intermediate layer comprising a second polyurethane composition containing an aromatic polyurethane, the aromatic polyurethane being present in an amount of at least 75 weight percent, wherein the total thickness of the multi-layered cover is no greater than 0.110 inches. 
   
     
     
         2 . The golf ball of  claim 1 , wherein the inner cover layer further comprises a polymer selected from the group consisting of polyesters; polyamides; polyamide-ethers, polyamide-esters;
 polyurethanes, polyureas; fluoropolymers; polystyrenes; polypropylenes and polyethylenes;   polyvinyl chlorides; polyvinyl acetates; polycarbonates; polyvinyl alcohols; polyethers;   polyimides, polyetherketones, polyamideimides; and mixtures thereof.   
     
     
         3 . The golf ball of  claim 1 , wherein the outer cover layer further comprises a polymer selected from the group consisting of aromatic polyurethanes, aromatic polyureas, and aromatic urethane-urea hybrids and copolymers and blends thereof. 
     
     
         4 . The golf ball of  claim 1 , wherein the intermediate cover layer further comprises a polymer selected from the group consisting of aliphatic polyurethanes, aliphatic polyureas, and aliphatic urethane-urea hybrids and copolymers and blends thereof. 
     
     
         5 . The golf ball of  claim 1 , wherein the total thickness of the cover is no greater than 0.095 inches. 
     
     
         6 . The golf ball of  claim 1 , wherein the thickness of the inner cover layer is about 0.010 to about 0.050 inches. 
     
     
         7 . The golf ball of  claim 1 , wherein the thickness of the outer cover layer is about 0.004 to about 0.020 inches. 
     
     
         8 . The golf ball of  claim 1 , wherein the thickness of the intermediate cover layer is about 0.010 to about 0.040 inches. 
     
     
         9 . The golf ball of  claim 1 , wherein the core is single-layered, the core being formed from a rubber composition. 
     
     
         10 . The golf ball of  claim 1 , wherein the core is dual-layered, the core comprising an inner core and surrounding outer core layer, at least one of the core layers being formed from a rubber composition. 
     
     
         11 . The golf ball of  claim 1 , wherein 70% or greater of the acid groups of the ethylene acid copolymer are neutralized. 
     
     
         12 . The golf ball of  claim 1 , wherein the ionomer composition further comprises a fatty acid or salt thereof. 
     
     
         13 . The golf ball of  claim 1 , wherein the ethylene acid copolymer is selected from the group consisting of ethylene/(meth)acrylic acid/n-butyl acrylate; ethylene/(meth)acrylic acid/ethyl acrylate; ethylene/(meth)acrylic acid/methyl acrylate; ethylene/(meth)acrylic acid/n-butyl acrylate; and ethylene/(meth)acrylic acid/isobutyl acrylate copolymers. 
     
     
         14 . The golf ball of  claim 1 , wherein the inner cover layer hardness is greater than the intermediate cover layer hardness by at least 5 Shore D units and the inner cover layer hardness is greater than the outer cover layer hardness by at least 5 Shore D units. 
     
     
         15 . The golf ball of  claim 1 , wherein the inner cover layer hardness is 60 Shore D units or greater. 
     
     
         16 . The golf ball of  claim 1 , wherein the inner cover layer hardness is 68 Shore D units or greater. 
     
     
         17 . The golf ball of  claim 1 , wherein the flex modulus of the inner cover layer is greater than the flex modulus of the intermediate cover layer by at least 5,000 psi and the flex modulus of the inner cover layer is greater than the flex modulus of the outer cover layer by at least 5,000 psi. 
     
     
         18 . The golf ball of  claim 1 , wherein the flex modulus of the inner cover layer is 50,000 psi or greater. 
     
     
         19 . The golf ball of  claim 1 , wherein the flex modulus of the inner cover layer is within the range of 60,000 psi to 120,000 psi. 
     
     
         20 . The golf ball of  claim 1 , wherein the difference between the intermediate cover layer hardness and outer cover layer hardness is no greater than 5 Shore D units. 
     
     
         21 . The golf ball of  claim 1 , wherein the difference between the flex modulus of the intermediate cover layer and the flex modulus of the outer cover layer is no greater than 5,000 psi. 
     
     
         22 . A golf ball, comprising:
 a core, and   a multi-layered cover having three layers, the multi-layered cover comprising:
 i) an inner cover layer comprising an ionomer composition containing ethylene acid copolymer having acid groups such that at least 30% of the acid groups are neutralized, the ethylene acid copolymer being present in an amount of at least 75 weight percent and the inner cover layer having an inner cover thickness (ICt); 
 ii) an outer cover layer comprising a first polyurethane composition containing aliphatic polyurethane, the aliphatic polyurethane being present in an amount of at least 75 weight percent and the outer cover layer having an outer cover thickness (OCt); and 
 iii) an intermediate cover layer disposed between the inner cover layer and outer cover layer, the intermediate cover layer comprising a second polyurethane composition containing an aromatic polyurethane, the aromatic polyurethane being present in an amount of at least 75 weight percent and the intermediate cover layer having an intermediate cover thickness (INTCt); wherein the ICt>OCt and ICt>INTCt. 
   
     
     
         23 . The golf ball of  claim 22 , wherein the aliphatic polyurethane is present in the first polyurethane composition in an amount of 100 weight percent and the aromatic polyurethane is present in the second polyurethane composition in an amount of 100 weight percent. 
     
     
         24 . A golf ball, comprising:
 a core, and   a multi-layered cover having three layers, the multi-layered cover comprising:
 i) an inner cover layer comprising an ionomer composition containing ethylene acid copolymer having acid groups such that at least 30% of the acid groups are neutralized, the ethylene acid copolymer being present in an amount of at least 75 weight percent and the inner cover layer having an inner cover thickness (ICt); 
 ii) an outer cover layer comprising a first polyurethane composition containing aliphatic polyurethane, the aliphatic polyurethane being present in an amount of at least 75 weight percent and the outer cover layer having an outer cover thickness (OCt); and 
 iii) an intermediate cover layer disposed between the inner cover layer and outer cover layer, the intermediate layer comprising a second polyurethane composition containing an aromatic polyurethane, the aromatic polyurethane being present in an amount of at least 75 weight percent and having an intermediate cover thickness (INTCt); wherein the INTCt≧OCt. 
   
     
     
         25 . The golf ball of  claim 24 , wherein the aliphatic polyurethane is present in the first polyurethane composition in an amount of 100 weight percent and the aromatic polyurethane is present in the second polyurethane composition in an amount of 100 weight percent.