Golf balls having multi-layered covers based on aromatic and aliphatic polyurethanes

Abstract

Golf balls having multi-layered covers and single or multi-layered cores are provided. The cover includes an inner cover layer made of an aromatic polyurethane composition; and outer cover layer made of an aliphatic polyurethane composition. Ethylene acid copolymer ionomers can be used to make a second inner cover layer. Preferably, the total thickness of the multi-layered cover is preferably no greater than 0.110 inches. Thermoplastic and thermoset polyurethanes can be used to form the cover. The invention also includes casting 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 having at least one layer, and   a multi-layered cover having at least two layers, the multi-layered cover comprising:
 i) an outer cover layer comprising a first polyurethane composition, the composition comprising aliphatic polyurethane, and the aliphatic polyurethane being present in an amount of at least 60 weight percent; and 
 iii) an inner cover layer disposed between the core and outer cover layer, the inner cover layer comprising a second polyurethane composition, the composition comprising aromatic polyurethane, and the aromatic polyurethane being present in an amount of at least 60 weight percent, at least one of the aliphatic and aromatic polyurethanes being a thermoplastic polyurethane, and 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 core is single-layered, the core being formed from a thermoset rubber composition. 
     
     
         3 . The golf ball of  claim 1 , wherein the rubber composition comprises polybutadiene rubber. 
     
     
         4 . The golf ball of  claim 1 , wherein the ball further comprises an intermediate layer disposed between the core and inner cover layer, the intermediate 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 60 weight percent. 
     
     
         5 . The golf ball of  claim 4 , wherein 70% or greater of the acid groups of the ethylene acid copolymer are neutralized. 
     
     
         6 . The golf ball of  claim 5 , wherein the ionomer composition further comprises a fatty acid or salt thereof. 
     
     
         7 . The golf ball of  claim 4 , 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. 
     
     
         8 . The golf ball of  claim 4 , wherein the intermediate 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. 
     
     
         9 . 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. 
     
     
         10 . The golf ball of  claim 1 , wherein the inner 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. 
     
     
         11 . The golf ball of  claim 1 , wherein the core is encapsulated by a moisture vapor barrier layer comprising a material selected from the group consisting of polybutadiene, natural rubber, butyl-based rubber, acrylics, trans-polyisoprene, neoprene, chlorinated polyethylene, balata, ethylene/methacrylic acid resins, and mixtures thereof. 
     
     
         12 . The golf ball of  claim 11 , wherein the moisture vapor barrier layer has a thickness of less than 0.010 inches. 
     
     
         13 . The golf ball of  claim 1 , wherein one of the polyurethane compositions is thermoset. 
     
     
         14 . The golf ball of  claim 1 , wherein at least one of the polyurethane compositions is applied by thermal spraying. 
     
     
         15 . The golf ball of  claim 1 , wherein at least one of the polyurethane compositions further comprises a plasticizer. 
     
     
         16 . The golf ball of  claim 15 , wherein the plasticizer is selected from the group consisting of dipropylene glycol-dibenzoate, ethyl oleate and propylene carbonate. 
     
     
         17 . A golf ball, comprising:
 a core having at least two layers, wherein at least one of the layers is formed from a thermoset rubber composition; and   a multi-layered cover having at least two layers, the multi-layered cover comprising:
 i) an outer cover layer comprising a first polyurethane composition, the composition comprising aliphatic polyurethane, the aliphatic polyurethane being present in an amount of at least 60 weight percent; and 
 ii) an inner cover layer disposed between the core and outer cover layer, the inner cover layer comprising a second polyurethane composition, the composition comprising aromatic polyurethane, the aromatic polyurethane being present in an amount of at least 60 weight percent, at least one of the aliphatic and aromatic polyurethanes being a thermoplastic polyurethane, wherein the total thickness of the multi-layered cover is no greater than 0.110 inches. 
   
     
     
         18 . The golf ball of  claim 17  wherein the rubber composition comprises polybutadiene rubber. 
     
     
         19 . The golf ball of  claim 17 , wherein at least one of the polyurethane compositions is applied by thermal spraying. 
     
     
         20 . The golf ball of  claim 1 , wherein at least one of the polyurethane compositions further comprises a plasticizer.