Golf balls having foam inner core and thermoset outer core layer
Multi-piece golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a foam composition, preferably foamed polyurethane. The outer core layer is preferably formed from a non-foamed thermoset composition such as polybutadiene rubber. The inner and outer core layers can have different hardness gradients. Preferably, the specific gravity (density) of the foam inner core is less than the density of the outer core layer. The ball further includes a cover of at least one layer and may include at least one casing layer. The core structure and resulting ball have relatively good resiliency.
1. A golf ball, comprising:
i) an inner core layer comprising a foamed composition, the inner core layer having a diameter in the range of about 0.100 to about 1.100 inches, a specific gravity (SG inner ), and an outer surface hardness (H inner core surface ) and a center hardness (H inner core center ), wherein the H inner core center is in the range of about 30 Shore C to about 78 Shore C and the H inner core surface is in the range of about 46 Shore C to about 95 Shore C, the H inner core surface being greater than the H inner core center to provide a positive hardness gradient;
ii) an outer core layer comprising a thermoset material, the outer core layer being disposed about the inner core layer and having a thickness in the range of about 0.100 to about 0.750 inches, a specific gravity (SG outer ), and an outer surface hardness (H outer surface of OC ) and an inner surface hardness (H inner surface of OC ), the H outer surface of OC being greater than the H inner surface of OC to provide a positive hardness gradient, wherein the SG outer , is greater than the SG inner ; and
iii) a cover having at least one layer, the cover being disposed about the outer core layer.
2. The golf ball of claim 1 , wherein the cover is single-layered.
3. The golf ball of claim 2 , wherein the cover comprises an ethylene acid copolymer ionomer composition.
4. The golf ball of claim 2 , wherein the cover comprises a polyurethane composition.
5. The golf ball of claim 2 , wherein the inner core comprises a foamed polyurethane composition.
6. The golf ball of claim 5 , wherein the foamed polyurethane composition is prepared by adding water to a mixture of polyisocyanate, polyol, and curing agent compounds, and catalyst, the water being added in a sufficient amount to cause the mixture to foam.
7. The golf ball of claim 2 , wherein the outer core layer comprises a thermoset rubber material.
8. The golf ball of claim 1 , wherein the cover comprises an inner cover layer and outer cover layer.
9. The golf ball of claim 8 , wherein the inner cover comprises an ethylene acid copolymer ionomer composition; and the outer cover comprises a polyurethane composition.
10. The golf ball of claim 8 , wherein the inner core comprises a foamed polyurethane composition.
11. The golf ball of claim 10 , wherein the foamed polyurethane composition is prepared by adding water to a mixture of polyisocyanate, polyol, and curing agent compounds, and catalyst, the water being added in a sufficient amount to cause the mixture to foam.
12. The golf ball of claim 8 , wherein the outer core layer comprises a thermoset rubber material.
13. A golf ball, comprising:
i) an inner core layer comprising a foamed composition, the inner core layer having a diameter in the range of about 0.100 to about 1.100 inches, a specific gravity (SG inner ), and an outer surface hardness (H inner core surface ) and a center hardness (H inner core center ), wherein the H inner core center is in the range of about 30 Shore C to about 78 Shore C and the H inner core surface is in the range of about 46 Shore C to about 95 Shore C, the H inner core surface being greater than the H inner core center to provide a positive hardness gradient;
ii) an outer core layer comprising a thermoset material, the outer core layer being disposed about the inner core and having a thickness in the range of about 0.100 to about 0.750 inches, a specific gravity (SG outer ), and an outer surface hardness (H outer surface of OC ) and an inner surface hardness (H inner surface of OC ), the H outer surface of OC being the same or less than the H inner surface of OC to provide a zero or negative hardness gradient, wherein the SG outer , is greater than the SG inner ; and
iii) a cover having at least one layer, the cover being disposed about the outer core layer.
14. The golf ball of claim 13 , wherein the cover comprises an ethylene acid copolymer ionomer composition.
15. The golf ball of claim 13 , wherein the cover comprises a polyurethane composition.
16. The golf ball of claim 13 , wherein the inner core comprises a foamed polyurethane composition.
17. The golf ball of claim 16 , wherein the foamed polyurethane composition is prepared by adding water to a mixture of polyisocyanate, polyol, and curing agent compounds, and catalyst, the water being added in a sufficient amount to cause the mixture to foam.
18. The golf ball of claim 13 , wherein the outer core layer comprises a thermoset rubber material.