Methods for making polyurea polymer and golf balls prepared therefrom
Methods for making golf balls having a cover made from a polyurea composition are provided. The golf balls include a rubber core and intermediate layer made from an olefin-based ionomer composition. The methods for making the polyurea composition involve preparing an amine-terminated first polymer by reacting isocyanate compound A with a stoichiometric excess of polyamine. The first prepolymer is reacted with a stoichiometric excess of isocyanate compound B to form an isocyanate-terminated second prepolymer. The second prepolymer is then reacted with a chain extender.
1. A method of forming a golf ball comprising a core formed from a rubber material, an intermediate layer formed from an olefin-based ionomer, and cover formed from a polyurea composition, the intermediate layer being disposed between the core and cover, and the polyurea composition being prepared by a reaction comprising the steps of:
i) forming an amine-terminated first prepolymer by reacting isocyanate compound A with a stoichiometric excess of polyamine compound;
ii) forming an isocyanate-terminated second prepolymer by reacting the first prepolymer with a stoichiometric excess of isocyanate compound B; and
iii) reacting the second prepolymer with an amine-terminated chain extender, wherein isocyanate compound A is 4,4′-diisocyanatodicyclohexylmethane diisocyanate (H 12 MDI) and isocyanate compound B is 1,6-hexamethylene diisocyanate (HDI) oligomer.
2. The method of claim 1 , wherein the rubber material is selected from the group consisting of polybutadiene rubber, polyisoprene rubber, natural rubber, ethylene-propylene rubber, ethylene-propylene diene rubber, styrene-butadiene rubber, and blends thereof.
3. The method of claim 2 , wherein the rubber material is polybutadiene rubber.
4. The method of claim 1 , wherein the rubber material is a blend of polybutadiene rubber and an elastomer selected from the group consisting of polyisoprene rubber, natural rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene-butadiene rubber, polystyrene elastomers, polyethylene elastomers, polyurethane elastomers, polyurea elastomers, acrylate rubbers, polyoctenamers, metallocene-catalyzed elastomers, and plastomers.
5. The method of claim 1 , wherein the olefin-based ionomer is an ethylene acid copolymer, the acid being selected from methacrylic acid, acrylic acid, maleic acid, crotonic acid, fumaric acid, and itaconic acid.
6. The method of claim 5 , wherein 10 to 80% of the acid groups in the olefin-based ionomer are neutralized.
7. The method of claim 1 , wherein 80 to 100% of the acid groups in the olefin-based ionomer are neutralized.
8. A method of forming a golf ball comprising a core formed from a rubber material, an intermediate layer formed from an olefin-based ionomer, and cover formed from a polyurea composition, the intermediate layer being disposed between the core and cover, and the polyurea composition being prepared by a reaction comprising the steps of:
i) forming an amine-terminated first prepolymer by reacting isocyanate compound A with a stoichiometric excess of polyamine compound;
ii) forming an isocyanate-terminated second prepolymer by reacting the first prepolymer with a stoichiometric excess of isocyanate compound B; and
iii) reacting the second prepolymer with an amine-terminated chain extender, wherein isocyanate compound A is 2,4-toluene diisocyanate (TDI) and isocyanate compound B is 4,4′-diphenylmethane diisocyanate (MDI).