Methods for treating thermoplastic polyurethane covers for golf balls with epoxy compositions
Golf balls having covers made of thermoplastic polyurethane compositions are provided. Multi-piece golf balls can be made. In one embodiment, the outer cover layer is formed from a composition comprising a thermoplastic polyurethane and epoxy compound. Mixtures of multi-functional amines and imines, and multi-functional isocyanates, and epoxy curing agents; and solvent, can be applied to the outer cover. The resulting coating may contain polyurethanes, polyureas, and hybrids, copolymers, and blends thereof. The cover composition and surface coatings can further include catalysts, ultraviolet (UV)-light stabilizers, and other additives. The coating methods have many benefits and the finished balls have good physical properties.
1 . A golf ball formed by a method, the method comprising the steps of:
providing a golf ball sub-assembly comprising at least one core layer;
forming an outer cover layer over the sub-assembly, wherein the outer cover layer is formed from a first composition comprising a thermoplastic polyurethane;
applying a second composition comprising an epoxy-functional compound to the outer cover layer; and
applying a third composition comprising an epoxy curing agent to the outer cover layer to form at least a partially cross-linked cover for the golf ball.
2 . The golf ball of claim 1 , wherein the epoxy-functional compound is selected from the group consisting of glycidyl methacrylate, glycidyl acrylate, diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, 1,4-cyclohexanedimethanol diglycidyl ether, 1,4-butanediol diglycidyl ether, trimethylolpropane triglycidyl ether; and mixtures thereof.
3 . The golf ball of claim 1 , wherein the epoxy curing agent is selected from the group consisting of amines, acids, anhydrides, imines, isocyanates, and hydroxyls, and mixtures thereof.
4 . The golf ball of claim 1 , wherein the epoxy curing agent is an isocyanate selected from the group consisting of 4,4′-methylene diphenyl diisocyanate; 2,4′-methylene diphenyl diisocyanate; toluene 2,4-diisocyanate; toluene 2,6-diisocyanate; 4,4′-dicyclohexylmethane diisocyanate; p-phenylene diisocyanate; isophorone diisocyanate ; 1,6-hexamethylene diisocyanate; and oligomers and homopolymers and copolymers and blends thereof.
5 . The golf ball of claim 1 , wherein the epoxy curing agent is polyaziridine.
6 . The golf ball of claim 1 , wherein the epoxy curing agent is an amine selected from the group consisting of diethylene toluene diamine, mono or di-isopropanolamine, methyl diethanol amine, methylene-bis-chloro diethylaniline, and dimethyl thiotoluene diamine, amino ethyl piperazine, and mixtures thereof.
7 . The golf ball of claim 1 , wherein the first composition further comprises an ultraviolet (UV) light stabilizer.
8 . The golf ball of claim 1 , wherein the first composition further comprises a catalyst.
9 . The golf ball of claim 8 , wherein the catalyst is selected from the group consisting of dibutyl tin dilaurate, dibutyl tin acetylacetonate, dibutyl tin dibutoxide, dibutyl tin sulfide, dibutyl tin di-2-ethylhexanoate, dibutyl tin (IV) diacetate, dialkyltin (IV) oxide, tributyl tin laurylmercaptate, dibutyl tin dichloride, organo lead, tetrabutyl titanate, tertiary amines, mercaptides, stannous octoate, potassium octoate, zinc octoate, diazo compounds, and potassium acetate, and mixtures thereof.