Multilayer core golf ball having hardness gradient within and between each core layer
A multi-layered core golf ball wherein each core layer comprises its own specific hardness gradient in addition to an overall specific hardness gradient from one core layer to the next. The inner core layer comprises a plurality of hardnesses of from about 50 Shore C to about 90 Shore C, a diameter of about 30 mm or lower, and a geometric center comprising a hardness greater than that of a first outer surface to define a negative hardness gradient of about 15 Shore C or greater. The outer core layer comprises a plurality of harnesses of from about 50 Shore C to about 95 Shore C, a thickness of about 10 mm or lower, and a second outer surface comprising a hardness greater than that of an inner surface to define a positive hardness gradient of about 20 Shore C or greater. A further outer core layer hardness, disposed in a region extending between about 10% and about 90% of the distance from the inner surface to the second outer surface, is greater than that of the inner and second outer surfaces. Also, the hardness of the second outer surface is similar to or less than that of the geometric center.
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 lower and having a plurality of hardnesses of from about 50 Shore C to about 90 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 15 Shore C or greater;
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 50 Shore C to about 95 Shore C, wherein the inner surface comprises a third hardness and the second outer surface comprises a fourth hardness, wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 20 Shore C or greater,
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 greater than the first hardness, the third hardness and the fourth hardness; and
wherein the fourth hardness is similar to or less than the first hardness.
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 inner core layer and the outer core layer each comprises peroxide in an amount of from about 0.2 phr to about 3.0 phr and antioxidant in an amount of about 2.5 phr or less.
4. The golf ball of claim 1 , wherein the ratio of antioxidant to initiator of the inner core layer is from about 0.33 to about 4.8.
5. The golf ball of claim 1 , wherein the diameter of the inner core layer is about 26 mm or lower.
6. The golf ball of claim 1 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 20 Shore C or greater.
7. The golf ball of claim 1 , wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 25 Shore C or greater.
8. 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 lower and having a plurality of hardnesses of from about 50 Shore C to about 90 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 15 Shore C or greater;
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 50 Shore C to about 80 Shore C, wherein the inner surface comprises a third hardness and the second outer surface comprises a fourth hardness, wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 15 Shore C or lower,
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 similar to or less than the first hardness and is greater than the third hardness and the fourth hardness; and
wherein the fourth hardness is less than the first hardness.
9. The golf ball of claim 8 , wherein the third hardness is similar to the second hardness.
10. The golf ball of claim 8 , wherein the inner core layer and the outer core layer each comprises peroxide in an amount of from about 0.2 phr to about 3.0 phr and antioxidant in an amount of about 2.5 phr or less.
11. The golf ball of claim 8 , wherein the ratio of antioxidant to initiator of the inner core layer is from about 0.33 to about 4.8.
12. The golf ball of claim 8 , wherein the diameter of the inner core layer is about 26 mm or lower.
13. The golf ball of claim 8 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 20 Shore C or greater.
14. The golf ball of claim 8 , wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 10 Shore C or lower.
15. 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 lower and having a plurality of hardnesses of from about 30 Shore D to about 68 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 greater;
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 30 Shore D to about 68 Shore D, wherein the inner surface comprises a third hardness and the second outer surface comprises a fourth hardness, wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 20 Shore D or greater,
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 greater than the first hardness, the third hardness and the fourth hardness; and
wherein the fourth hardness is similar to or less than the first hardness.
16. The golf ball of claim 15 , wherein the third hardness is similar to the second hardness.
17. The golf ball of claim 15 , wherein the inner core layer and the outer core layer each comprises peroxide in an amount of from about 0.2 phr to about 3.0 phr and antioxidant in an amount of about 2.5 phr or less.
18. The golf ball of claim 15 , wherein the ratio of antioxidant to initiator of the inner core layer is from about 0.33 to about 4.8.
19. The golf ball of claim 15 , wherein the diameter of the inner core layer is about 26 mm or lower.
20. The golf ball of claim 15 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 25 Shore D or greater.
21. The golf ball of claim 15 , wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 25 Shore D or greater.
22. 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 lower and having a plurality of hardnesses of from about 30 Shore D to about 68 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 greater;
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 30 Shore D to about 55 Shore D, wherein the inner surface comprises a third hardness and the second outer surface comprises a fourth hardness, wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 15 Shore D or lower,
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 similar to or less than the first hardness and is greater than the third hardness and the fourth hardness; and
wherein the fourth hardness is less than the first hardness to define a negative hardness gradient of about 10D or greater.
23. The golf ball of claim 22 , wherein the third hardness is similar to the second hardness.
24. The golf ball of claim 22 , wherein the diameter of the inner core layer is about 26 mm or lower.
25. The golf ball of claim 22 , wherein the inner core layer and the outer core layer each comprises peroxide in an amount of from about 0.2 phr to about 3.0 phr and antioxidant in an amount of about 2.5 phr or less.
26. The golf ball of claim 22 , wherein the ratio of antioxidant to initiator of the inner core layer is from about 0.33 to about 4.8.
27. The golf ball of claim 22 , wherein the first hardness is greater than the second hardness to define a negative hardness gradient of about 25 Shore D or greater.
28. The golf ball of claim 22 , wherein the fourth hardness is greater than the third hardness to define a positive hardness gradient of about 10 Shore D or lower.