Multi-layer core golf ball
View Patent ↗Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises a zero or positive hardness gradient center that is hard relative to an intermediate core layer. The overall core preferably has a zero hardness gradient, a negative hardness gradient, or a positive hardness gradient of up to 20 Shore C units.
1. A golf ball comprising a core and a cover, wherein the core has an overall diameter of from 1.40 inches to 1.62 inches and comprises:
a center having a diameter of from 0.100 inches to 0.950 inches, a center Shore C hardness (H center ) of 90 or less, an outer surface Shore C hardness (H center surface ) of 75 or greater, wherein H center surface >H center ;
an intermediate core layer having an outer surface Shore C hardness (H intermediate ) of 85 or less; and
an outer core layer having an outer surface Shore C hardness (H outer core ) of 80 or greater;
wherein H intermediate <H center surface , H intermediate <H outer core , and H outer core −H center ≦20.
2. The golf ball of claim 1 , wherein H outer core −H center ≧15.
3. The golf ball of claim 1 , wherein H outer core −H center ≧10.
4. The golf ball of claim 1 , wherein H outer core −H center ≧0.
5. The golf ball of claim 1 , wherein the specific gravity of the outer core layer is within 0.01 g/cc of the specific gravity of the intermediate core layer.
6. The golf ball of claim 1 , wherein the center is formed from a rubber composition.
7. The golf ball of claim 1 , wherein the overall diameter of the core is from 1.500 inches to 1.580 inches.
8. The golf ball of claim 1 , wherein the diameter of the center is from 0.125 inches to 0.750 inches.
9. The golf ball of claim 1 , wherein the diameter of the center is from 0.250 inches to 0.675 inches.
10. The golf ball of claim 1 , wherein the intermediate core layer and the outer core layer each have a specific gravity of from 1.13 g/cc to 1.18 g/cc.
11. The golf ball of claim 1 , wherein the intermediate core layer and the outer core layer each have a specific gravity of from 1.09 g/cc to 1.19 g/cc.
12. The golf ball of claim 1 , wherein H center surface is from 75 to 89 and H center is less than 89.
13. The golf ball of claim 12 , wherein H outer core is 85 or greater.
14. The golf ball of claim 12 , wherein H outer core is 89 or greater.
15. The golf ball of claim 1 , wherein H intermediate is 80 or less.
16. The golf ball of claim 1 , wherein a subassembly consisting of the center and the intermediate core layer has a compression of 55 or less.
17. The golf ball of claim 16 , wherein the golf ball has an overall compression of from 60 to 100.
18. The golf ball of claim 1 , wherein the cover consists of:
an inner cover layer having an outer surface hardness of 65 Shore D or greater and a thickness of from 0.020 inches to 0.080 inches, and
an outer cover layer having an outer surface hardness of 60 Shore D or less and a thickness of from 0.015 inches to 0.055 inches.
19. The golf ball of claim 1 , wherein the cover consists of:
an inner cover layer formed from a partially or fully neutralized ionomer composition and having an outer surface hardness of 65 Shore D or greater and a thickness of from 0.030 inches to 0.040 inches, and
an outer cover layer formed from a polyurethane or polyurea composition and having an outer surface hardness of 50 Shore D or less and a thickness of from 0.025 inches to 0.035 inches.