Method of manufacturing a golf ball including a blend of highly neutralized acid polymers

1. A method of making a golf ball, the method comprising:

a. forming an ionomer-based masterbatch by blending an ionomer resin and at least one additive comprising an inorganic filler and subjecting the blend to water-cooled granulation;

b. processing a blend comprising a first highly neutralized acid polymer having a first Vicat softening temperature and a first specific gravity, a second highly neutralized acid polymer having a second Vicat softening temperature and a second specific gravity, and the ionomer-based masterbatch, wherein the ionomer resin has a third Vicat softening temperature and a third specific gravity, to form a blend-containing core layer of a golf ball that essentially encloses any prior layers of the golf ball; and

c. forming a second layer essentially enclosing the blend-containing layer;

d. forming a cover layer essentially enclosing previously-formed layers,

wherein the first, second, and third Vicat softening temperatures are each independently between about 48° C. and about 65° C.; and further wherein the absolute values of the differences among Vicat softening temperatures is no more than about 15° C.; and the absolute values of the differences among the first, second, and third specific gravities are no more than about 0.015; and the moisture content of the first and second highly neutralized acid polymers is ≦1000 ppm.

2. The method of claim 1 , wherein the absolute values of the differences among the Vicat softening temperatures are no more than about 10° C.

3. The method of claim 1 , wherein the core layer is an inner core layer formed by injection molding and the inner core layer has a diameter of from about 21 mm to about 28 mm.

4. The method of claim 1 , wherein the second layer is an outer core layer formed by compression molding of rubber comprising polybutadiene and the outer core layer has a thickness of between about 5 mm and about 9 mm.

5. The method of claim 1 , further comprising forming an intermediate layer between the second layer and the cover layer by injection molding or compression molding a thermoplastic material comprising at least one of an ionomer resin, a highly neutralized acid polymer, a polyamide resin, a polyurethane resin, a polyester resin, and a combination thereof.

6. The method of claim 3 , wherein the second layer is an outer core layer formed by compression molding of rubber comprising polybutadiene and the outer core layer has a thickness of between about 5 mm and about 9 mm.

7. The method of claim 6 , further comprising forming an intermediate layer between the outer core layer and the cover layer by injection molding or compression molding a thermoplastic material comprising at least one of an ionomer resin, a highly neutralized acid polymer, a polyamide resin, a polyurethane resin, a polyester resin, and a combination thereof.

8. The method of claim 6 , wherein the cover layer is formed by injection molding or compression molding a thermoplastic material comprising at least one of an ionomer resin, a highly neutralized acid polymer, a polyamide resin, a polyurethane resin, a polyester resin, and a combination thereof.

9. The method of claim 5 , wherein the cover layer is formed by injection molding or compression molding a thermoplastic material comprising at least one of an ionomer resin, a highly neutralized acid polymer, a polyamide resin, a polyurethane resin, a polyester resin, and a combination thereof.

10. The method of claim 7 , wherein the cover layer is formed by injection molding or compression molding a thermoplastic material comprising at least one of an ionomer resin, a highly neutralized acid polymer, a polyamide resin, a polyurethane resin, a polyester resin, and a combination thereof.

11. The method of claim 10 , wherein the thermoplastic material of the cover layer comprises a crosslinked thermoplastic polyurethane elastomer including crosslinks formed from allyl ether side groups, and said crosslinked thermoplastic polyurethane elastomer is a reaction product formed from reacting an organic isocyanate with a mixture of the following reactants:

(c) a diol having 2 primary hydroxyl groups and at least 1 pendant unsaturation having the following formula:

in which R 1 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted alkyl-aryl group, substituted or unsubstituted ether group, substituted or unsubstituted ester group, any combination thereof, or H, and may optionally include an unsaturated bond in any main chain or side chain of any group; R 2 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted alkyl-aryl group, substituted or unsubstituted ether group, substituted or unsubstituted ester group, any combination thereof, and R 2 includes an allyl group; and x and y are integers independently having any value from 1 to 10;

(b) a chain extender having at least two reaction sites with isocyanates and having a molecular weight of less than about 450;

(c) a long chain polyol having a molecular weight of between about 500 and about 4,000; and

(d) a sufficient amount of free radical initiator, so as to be capable of generating free radicals that induce crosslinking structures in the hard segments by free radical initiation.

12. The method of claim 8 , wherein the thermoplastic material comprises a crosslinked thermoplastic polyurethane elastomer including crosslinks formed from allyl ether side groups, and said crosslinked thermoplastic polyurethane elastomer is a reaction product formed from reacting an organic isocyanate with a mixture of the following reactants:

(a) a diol having 2 primary hydroxyl groups and at least 1 pendant unsaturation having the following formula:

in which R 1 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted alkyl-aryl group, substituted or unsubstituted ether group, substituted or unsubstituted ester group, any combination thereof, or H, and may optionally include an unsaturated bond in any main chain or side chain of any group; R 2 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted alkyl-aryl group, substituted or unsubstituted ether group, substituted or unsubstituted ester group, any combination thereof, and R 2 includes an allyl group; and x and y are integers independently having any value from 1 to 10;

(b) a chain extender having at least two reaction sites with isocyanates and having a molecular weight of less than about 450;

(c) a long chain polyol having a molecular weight of between about 500 and about 4,000; and

(d) a sufficient amount of free radical initiator, so as to be capable of generating free radicals that induce crosslinking structures in the hard segments by free radical initiation.

13. The method of claim 9 , wherein the thermoplastic material of the cover layer comprises a crosslinked thermoplastic polyurethane elastomer including crosslinks formed from allyl ether side groups, and said crosslinked thermoplastic polyurethane elastomer is a reaction product formed from reacting an organic isocyanate with a mixture of the following reactants:

(b) a diol having 2 primary hydroxyl groups and at least 1 pendant unsaturation having the following formula:

in which R 1 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted alkyl-aryl group, substituted or unsubstituted ether group, substituted or unsubstituted ester group, any combination thereof, or H, and may optionally include an unsaturated bond in any main chain or side chain of any group; R 2 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted alkyl-aryl group, substituted or unsubstituted ether group, substituted or unsubstituted ester group, any combination thereof, and R 2 includes an allyl group; and x and y are integers independently having any value from 1 to 10;

(b) a chain extender having at least two reaction sites with isocyanates and having a molecular weight of less than about 450;

(c) a long chain polyol having a molecular weight of between about 500 and about 4,000; and

(d) a sufficient amount of free radical initiator, so as to be capable of generating free radicals that induce crosslinking structures in the hard segments by free radical initiation.

14. The method of claim 11 , wherein the unsaturated diol is trimethylolpropane monoallyl ether (TMPME) and the cover layer has a flexural modulus of less than 1,000 psi.

15. The method of claim 12 , wherein the unsaturated diol is trimethylolpropane monoallyl ether (TMPME) and the cover layer has a flexural modulus of less than 1,000 psi.

16. The method of claim 13 , wherein the unsaturated diol is trimethylolpropane monoallyl ether (TMPME) and the cover layer has a flexural modulus of less than 1,000 psi.