Methods for making polyurea and polyurethane polymers and golf balls prepared therefrom

1. A method of forming a golf ball comprising:

providing a golf ball core;

forming a first hydroxyl-terminated prepolymer by reacting a first isocyanate compound with a stoichiometric excess of polyol compound;

forming an isocyanate-terminated second prepolymer by reacting the first hydroxyl-terminated prepolymer with a stoichiometric excess of a second isocyanate compound,

wherein the first isocyanate compound and the second isocyanate compound are different chemical compounds, and

wherein the first isocyanate compound and the second isocyanate compound are each selected from the group consisting of 1,4, cyclohexyl diisocyanate (CHDI); 4,4′-diphenylmethane diisocyanate (MDI); 2,4-toluene diisocyanate (TDI); 1,6-hexamethylene diisocyanate (HDI); 2,6-toluene diisocyanate; trimethyl hexamethylene diisocyanate (TMDI); 3,3′-dimethyl-4,4′-biphenyl diisocyanate (TODD); p-phenylene diisocyanate (PPDI); dodecane diisocyanate (C 12 DI); m-tetramethylene xylene diisocyanate (TMXDI); 1,4-benzene diisocyanate; trans-cyclohexane-1,4-diisocyanate; 1,5-naphthalene diisocyanate (NDI); and 4,6-xylyene diisocyanate (XDI);

reacting the second prepolymer with a hydroxyl-terminated chain extender to form a polyurethane composition; and

forming a cover disposed about the core comprising the polyurethane composition.

2. The method of claim 1 , wherein the core comprises polybutadiene rubber, polyisoprene rubber, natural rubber, ethylene-propylene rubber, ethylene-propylene diene rubber, styrene-butadiene rubber, or blends thereof.

3. The method of claim 1 , further comprising the step of providing an intermediate layer disposed about the core to form an inner ball.

4. The method of claim 3 , wherein the intermediate layer comprises an olefin-based ionomer.

5. The method of claim 4 , wherein the olefin-based ionomer is an ethylene acid copolymer, and wherein the acid comprises methacrylic acid, acrylic acid, maleic acid, crotonic acid, fumaric acid, or itaconic acid.

6. The method of claim 5 , wherein 10 to 80 percent of the acid groups in the olefin-based ionomer are neutralized.

7. The method of claim 5 , wherein 80 to 100 percent of the acid groups in the olefin-based ionomer are neutralized.

8. The method of claim 1 , wherein the polyurethane composition comprises a uniform distribution of hard and soft segments.

9. A method of forming a golf ball comprising:

providing a core comprising a rubber material;

providing an intermediate layer comprising an olefin-based ionomer;

forming a polyurethane composition by:

forming a first prepolymer by reacting a first isocyanate compound with a stoichiometric excess of a hydroxyl-terminated compound;

forming a second prepolymer by reacting the first prepolymer with a stoichiometric excess of a second isocyanate compound,

wherein the first isocyanate compound and the second isocyanate compound are different chemical compounds, and

wherein the first isocyanate compound and the second isocyanate compound are each selected from the group consisting of 1,4,cyclohexyl diisocyanate (CHDI); 4,4′-diphenylmethane diisocyanate (MDI); 2,4-toluene diisocyanate (TDI); 2,6-toluene diisocyanate; 1,6-hexamethylene diisocyanate (HDI); and trimethyl hexamethylene diisocyanate (TMDI); and

reacting the second prepolymer with a chain extender; and

forming a cover disposed about the intermediate layer comprising the polyurethane composition.

10. The method of claim 9 , wherein the first prepolymer comprises hydroxyl groups at the terminal ends.

11. The method of claim 9 , wherein the rubber material comprises polybutadiene rubber.

12. The method of claim 9 , wherein the rubber material comprises 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.

13. The method of claim 9 , wherein the polyurethane composition comprises a uniform distribution of hard and soft segments.

14. A method of forming a golf ball comprising:

providing a core;

disposing an intermediate layer about the core to form an inner ball;

forming a polyurethane composition by:

forming a first prepolymer by reacting a first isocyanate compound with a stoichiometric excess of a hydroxyl-terminated compound;

forming a second prepolymer by reacting the first prepolymer with a stoichiometric excess of a second isocyanate compound,

wherein the first isocyanate compound is 2,4-toulene diisocyanate (TDI) and the second isocyanate compound is 4,4′-diphenylmethane diisocyanate (MDI); and

reacting the second prepolymer with a chain extender; and

forming a cover disposed about the inner ball comprising the polyurethane composition.

15. The method of claim 14 , wherein the core comprises polybutadiene rubber, polyisoprene rubber, natural rubber, ethylene-propylene rubber, ethylene-propylene diene rubber, styrene-butadiene rubber, or blends thereof.

16. The method of claim 14 , wherein the chain extender comprises hydroxyl groups.

17. The method of claim 14 , wherein the hydroxyl-terminated compound has a first molecular weight, wherein the first prepolymer has a second molecular weight that is greater than the first molecular weight, and wherein the second prepolymer has a third molecular weight greater than the second molecular weight.

18. The method of claim 14 , wherein the polyurethane composition comprises a uniform distribution of hard and soft segments.