A high CoR golf ball having predetermined moment of inertia is provided. A portion of the golf ball preferably contains substantially no filler, which contributes to the increased resilience of the ball. In accordance to one aspect of the invention, the portion with substantially no filler is an intermediate layer of the ball, and preferably is the outer core layer of the ball. The remaining portions of the ball preferably contribute to the moment of inertia of the ball. To craft a low moment of inertia ball, the innermost core should have a high specific gravity. Additionally, the outermost layers of the ball may have a low specific gravity. Conversely, to craft a high moment of inertia ball, the ball should have a thin dense layer positioned radially outward from its centroid radius. Additionally, the innermost core may have a low specific gravity. To craft a mid range moment of inertia ball, the ball may comprise a high specific gravity inner core and a thin dense layer. Preferably, the portion with substantially no filler is relatively larger than other portions of the ball.
1. A golf ball comprising:
a core comprised of an inner core and an outer core, a thin dense layer disposed around the outer core and a cover disposed about the thin dense layer;
wherein said thin dense layer has a thickness between about 0.001 and about 0.050 inches and a specific gravity of greater than 1.8;
wherein said inner core comprises a specific-gravity-reducing agent, has a diameter from about 0.50 inch to about 1.54 inches and has a specific gravity of less than 0.9, and
wherein the outer core has thickness of about 0.05 inch to about 0.575 inch, has a specific gravity of about 0.5 to about 1.05 and is substantially free of fillers.
2. The golf ball of claim 1 , wherein the cover has a Shore D hardness of less than 65.
3. The golf ball of claim 2 , wherein the cover has a Shore D hardness of less than 60.
4. The golf ball of claim 1 , wherein the outer core has a specific gravity of about 0.8 to about 0.96.
5. The golf ball of claim 1 , wherein the specific gravity of the outer core is higher than the specific gravity of the inner core.
6. The golf ball of claim 1 , wherein the inner core comprises a polymer selected from a group consisting of partially or fully neutralized ionomer, metallocene or other catalyzed polymer, polyurethane, silicone, thermoplastic elastomer, thermosetting elastomer, metal salt of a fatty acid, and melt processible composition, which comprises a highly neutralized ethylene copolymer and one or more aliphatic, mono-functional organic acids having fewer than 36 carbon atoms of salts thereof, wherein greater than 90% of all the acid of the ethylene copolymer is neutralized.
7. The golf ball of claim 1 , wherein the cover comprises a material selected from a group consisting of polyurethane, partially or fully neutralized ionomer, polyurea, polyurethane ionomer, metallocene or other catalyzed polymer, silicone, metal salt of a fatty acid and melt processible composition, which comprises a highly neutralized ethylene copolymer and one or more aliphatic, mono-functional organic acids having fewer than 36 carbon atoms of salts thereof, wherein greater than 90% of all the acid of the ethylene copolymer is neutralized.
8. The golf ball of claim 1 , wherein the cover comprises a polymer selected from a group consisting of compression molded thermoset polyurethane, compression molded thermoplastic polyurethane, compression molded thermoset polyurethane copolymer, compression molded thermoplastic polyurethane copolymer, injection molded thermoset polyurethane, injection molded thermoplastic polyurethane, injection molded thermoset polyurethane copolymer, injection molded thermoplastic polyurethane copolymer, reaction injection molded thermoset polyurethane, reaction injection molded thermoplastic polyurethane, reaction injection molded thermoset polyurethane copolymer, reaction injection molded thermoplastic polyurethane copolymer, cast thermoplastic polyurethane, cast thermosetting polyurethane, cast thermoplastic polyurethane copolymer, and cast thermosetting polyurethane copolymer.
9. The golf ball of claim 1 , wherein in the inner core comprises a polymer selected from a group consisting of chemically foamed thermoplastic, physically foamed thermoplastic, chemically foamed thermoset and physically foamed thermoset.
10. The golf ball of claim 1 , wherein the thin dense layer has a specific gravity of greater than 2.0.
11. The golf ball of claim 1 , wherein the outer core is formed from a polybutadiene rubber having a Mooney viscosity between about 40 and about 60.
12. The golf ball of claim 1 , wherein the core has a compression of less than 80.
13. The golf ball of claim 1 , wherein the outer core is a deformation zone that is substantially free of filler such that it has the highest content of polybutadiene rubber.
14. The golf ball of claim 13 , wherein the outer core is comprised of a zinc diacrylate containing less than about 10% zinc stearate.