Golf balls having multi-layered covers based on castable thermoplastic polyurethanes

Abstract

Golf balls having multi-layered covers are provided. Preferably, the ball includes an inner cover layer made of an aromatic polyurethane composition; and an outer cover layer made of an aliphatic polyurethane composition. At least one of the cover layers is formed by casting an aromatic or aliphatic thermoplastic polyurethane composition. Ethylene acid copolymer ionomers can be used to make a second inner cover layer. The cover layers are disposed about a single or multi-layered core. 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 cover layers being formed by casting an aliphatic or aromatic thermoplastic polyurethane. 
   
     
     
         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 core is dual-layered and at least one of the layers comprises a thermoset rubber composition. 
     
     
         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 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. 
     
     
         9 . 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. 
     
     
         10 . The golf ball of  claim 1 , wherein the inner cover layer is formed by casting an aromatic thermoplastic polyurethane composition and the outer cover layer is formed by casting an aliphatic thermoplastic polyurethane composition. 
     
     
         11 . The golf ball of  claim 1 , wherein the inner cover layer is formed by casting an aromatic thermoset polyurethane composition and the outer cover layer is formed by casting an aliphatic thermoplastic polyurethane composition. 
     
     
         12 . The golf ball of  claim 1 , wherein the inner cover layer is formed by casting an aromatic thermoplastic polyurethane composition and the outer cover layer is formed by casting an aliphatic thermoset polyurethane composition. 
     
     
         13 . The golf ball of  claim 1 , wherein at least one of the cover layers is formed by thermal spraying. 
     
     
         14 . The golf ball of  claim 1 , wherein at least one of the polyurethane compositions further comprises a plasticizer. 
     
     
         15 . The golf ball of  claim 14 , wherein the plasticizer is selected from the group consisting of dipropylene glycol-dibenzoate, ethyl oleate and propylene carbonate. 
     
     
         16 . 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. 
     
     
         17 . The golf ball of  claim 16 , wherein the moisture vapor barrier layer has a thickness of less than 0.010 inches.