Multilayer core golf ball having hardness gradient within and between each core layer
View Patent ↗The present invention is directed to an improved multi-layered core golf ball wherein each core layer comprises its own specific hardness gradient (positive, negative or a combination) in addition to an overall specific hardness gradient from one core layer to the next. In one embodiment, the golf ball comprises a two layer core and a cover disposed about the two layer core. The inner core layer has a plurality of hardnesses of from about 50 Shore C to about 80 Shore C and a first hardness greater than a second hardness to define a negative hardness gradient of about 20 Shore C or less. The outer core layer has a plurality of hardnesses of from about 45 Shore C to about 65 Shore C, a fourth hardness greater than a third hardness, and a fifth hardness less than the third hardness and the fourth hardness. Finally, the fourth hardness is less than the first hardness to define a two layer core having a negative hardness gradient of no greater than about 20 Shore C.
1. A golf ball comprising:
a two layer core and a cover disposed about the two layer core,
the two layer core comprising an inner core layer and an outer core layer disposed about the inner core layer,
said inner core layer comprising a geometric center and a first outer surface and being formed from a substantially homogenous formulation and having a diameter of about 30 mm or less and having a plurality of hardnesses of from about 50 Shore C to about 80 Shore C,
the geometric center comprising a first hardness and the first outer surface comprising a second hardness wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 20 Shore C or less,
said outer core layer comprising an inner surface and a second outer surface and being formed from a substantially homogenous formulation and comprising a thickness of about 10 mm or less and having a plurality of hardnesses of from about 45 Shore C to about 65 Shore C,
the inner surface comprising a third hardness and the second outer surface comprising a fourth hardness, wherein the fourth hardness is greater than the third hardness,
the outer core layer further comprising a fifth hardness disposed between the inner surface and the second outer surface in a region extending between about 10% and about 90% of the distance from the inner surface to the second outer surface, wherein the fifth hardness is less than the third hardness and the fourth hardness, and
wherein the fourth hardness is less than the first hardness to define a two layer core having a negative hardness gradient of no greater than about 20 Shore C.
2. The golf ball of claim 1 , wherein the third hardness is similar to the second hardness.
3. The golf ball of claim 1 , wherein the diameter of the inner core layer is about 26 mm or less.
4. The golf ball of claim 1 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 15 Shore C or less.
5. The golf ball of claim 1 , wherein the fourth hardness is less than the first hardness to define a two layer core having a negative hardness gradient of no greater than about 15 Shore C.
6. The golf ball of claim 1 , wherein the inner core layer comprises antioxidant in an amount of from about 0.2 phr to about 2.5 phr and the outer core layer comprises antioxidant in an amount of about 1.2 phr or less.
7. The golf ball of claim 1 , wherein the inner core layer comprises peroxide in an amount of from about 0.5 phr to about 2.0 phr and the outer core comprises peroxide in an amount of from about 0.6 phr to about 2.5 phr.
8. The golf ball of claim 1 , wherein the ratio of antioxidant to peroxide for the inner core layer is about 2.5 or less.
9. The golf ball of claim 1 , wherein the ratio of antioxidant to peroxide for the outer core layer is about 2.0 or less.
10. A golf ball comprising:
a two layer core and a cover disposed about the two layer core,
the two layer core comprising an inner core layer and an outer core layer disposed about the inner core layer,
said inner core layer comprising a geometric center and a first outer surface and being formed from a substantially homogenous formulation and having a diameter of about 30 mm or less and having a plurality of hardnesses of from about 50 Shore C to about 80 Shore C,
the geometric center comprising a first hardness and the first outer surface comprising a second hardness wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 23 Shore C or less;
said outer core layer comprising an inner surface and a second outer surface and being formed from a substantially homogenous formulation and comprising a thickness of about 10 mm or less and having a plurality of hardnesses of from about 50 Shore C to about 80 Shore C,
the inner surface comprising a third hardness and the second outer surface comprising a fourth hardness wherein the fourth hardness is greater than the third hardness, and
wherein the fourth hardness is similar to the first hardness.
11. The golf ball of claim 10 , wherein the third hardness is similar to the second hardness.
12. The golf ball of claim 10 , wherein the diameter of the inner core layer is about 26 mm or less.
13. The golf ball of claim 10 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 18 Shore C or less.
14. The golf ball of claim 10 , wherein the inner core layer comprises antioxidant in an amount of from about 0.2 phr to about 2.5 phr and the outer core layer comprises antioxidant in an amount of about 1.2 phr or less.
15. The golf ball of claim 10 , wherein the inner core layer comprises peroxide in an amount of from about 0.5 phr to about 2.0 phr and the outer core comprises peroxide in an amount of from about 0.6 phr to about 2.5 phr.
16. The golf ball of claim 10 , wherein the ratio of antioxidant to peroxide for the inner core layer is about 2.5 or less.
17. The golf ball of claim 10 , wherein the ratio of antioxidant to peroxide for the outer core layer is about 2.0 or less.
18. A golf ball comprising:
a two layer core and a cover disposed about the two layer core,
the two layer core comprising an inner core layer and an outer core layer disposed about the inner core layer,
said inner core layer comprising a geometric center and a first outer surface and being formed from a substantially homogenous formulation and having a diameter of about 30 mm or less and having a plurality of hardnesses of from about 25 Shore D to about 55 Shore D,
the geometric center comprising a first hardness and the first outer surface comprising a second hardness wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 20 Shore D or less;
said outer core layer comprising an inner surface and a second outer surface and being formed from a substantially homogenous formulation and comprising a thickness of about 10 mm or lower and having a plurality of hardnesses of from about 25 Shore D to about 40 Shore D,
the inner surface comprising a third hardness and the second outer surface comprising a fourth hardness, wherein the fourth hardness is greater than the third hardness,
the outer core layer further comprising a fifth hardness disposed between the inner surface and the second outer surface in a region extending between about 10% and about 90% of the distance from the inner surface to the second outer surface, wherein the fifth hardness is less than the third hardness and the fourth hardness, and
wherein the fourth hardness is less than the first hardness to define a two layer core having a negative hardness gradient of from about 10 Shore D to about 25 Shore D.
19. The golf ball of claim 18 , wherein the third hardness is similar to the second hardness.
20. The golf ball of claim 18 , wherein the diameter of the inner core layer is about 26 mm or less.
21. The golf ball of claim 18 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 15 Shore D or less.
22. The golf ball of claim 18 , wherein the fourth hardness is less than the first hardness to define a two layer core having a negative hardness gradient of from about 13 Shore D to about 21 Shore D.
23. The golf ball of claim 18 , wherein the inner core layer comprises antioxidant in an amount of from about 0.2 phr to about 2.5 phr and the outer core layer comprises antioxidant in an amount of about 1.2 phr or less.
24. The golf ball of claim 18 , wherein the inner core layer comprises peroxide in an amount of from about 0.5 phr to about 2.0 phr and the outer core comprises peroxide in an amount of from about 0.6 phr to about 2.5 phr.
25. The golf ball of claim 18 , wherein the ratio of antioxidant to peroxide for the inner core layer is about 2.5 or less.
26. The golf ball of claim 18 , wherein the ratio of antioxidant to peroxide for the outer core layer is about 2.0 or less.
27. A golf ball comprising:
a two layer core and a cover disposed about the two layer core,
the two layer core comprising an inner core layer and an outer core layer disposed about the inner core layer,
said inner core layer comprising a geometric center and a first outer surface and being formed from a substantially homogenous formulation and having a diameter of about 30 mm or less and having a plurality of hardnesses of from about 25 Shore D to about 55 Shore D,
the geometric center comprising a first hardness and the first outer surface comprising a second hardness wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 25 Shore D or less;
said outer core layer comprising an inner surface and a second outer surface and being formed from a substantially homogenous formulation and comprising a thickness of about 10 mm or less and having a plurality of hardnesses of from about 20 Shore D to about 55 Shore D,
the inner surface comprising a third hardness and the second outer surface comprising a fourth hardness wherein the fourth hardness is greater than the third hardness, and
wherein the fourth hardness is similar to the first hardness.
28. The golf ball of claim 27 , wherein the third hardness is similar to the second hardness.
29. The golf ball of claim 27 , wherein the diameter of the inner core layer is about 26 mm or less.
30. The golf ball of claim 27 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 20 Shore D or less.
31. The golf ball of claim 27 , wherein the inner core layer comprises antioxidant in an amount of from about 0.2 phr to about 2.5 phr and the outer core layer comprises antioxidant in an amount of about 1.2 phr or less.
32. The golf ball of claim 27 , wherein the inner core layer comprises peroxide in an amount of from about 0.5 phr to about 2.0 phr and the outer core comprises peroxide in an amount of from about 0.6 phr to about 2.5 phr.
33. The golf ball of claim 27 , wherein the ratio of antioxidant to peroxide for the inner core layer is about 2.5 or less.
34. The golf ball of claim 27 , wherein the ratio of antioxidant to peroxide for the outer core layer is about 2.0 or less.