Multi-layer core golf ball having opposing hardness gradient with steep gradient inner core layer
View Patent ↗A golf ball comprising an inner core having an outer surface and a geometric center and being formed from a substantially homogenous rubber composition, the rubber composition comprising a base rubber and a resorcinol such that the geometric center has a hardness of 40 to 60 Shore C and the outer surface has a hardness of 70 to 95 Shore C. An outer core layer is disposed about the inner core and has an outer surface having a hardness of 50 to 75 Shore C, an inner surface having a hardness of 51 to 76 Shore C, and is formed from a substantially homogenous composition. A cover layer is disposed about the outer core layer. The hardness of the inner core outer surface is greater than the hardness of the geometric center to define a positive hardness gradient of greater than 20 Shore C, and the hardness of the outer core outer surface is lower than the hardness of its inner surface to define a negative hardness gradient of −1 to −5 Shore C.
1. A golf ball comprising:
an inner core having a first outer surface and a geometric center and being formed from a first substantially homogenous rubber composition throughout, the rubber composition comprising a base rubber and a resorcinol such that the geometric center has a hardness of 40 to 60 Shore C and the first outer surface has a hardness of 70 or greater;
an outer core layer disposed about the inner core, the outer core layer having a second outer surface having a hardness of 50 to 75 Shore C and an inner surface having a hardness of 51 to 76 Shore C and being formed from a second substantially homogenous composition throughout; and
a cover layer disposed about the outer core layer;
wherein the geometric center, the first and second outer surfaces, and the inner surface each have a hardness, the hardness of the first outer surface being greater than the hardness of the geometric center to define a positive hardness gradient of greater than 20 Shore C, and the hardness of the second outer surface being lower than the hardness of the inner surface to define a negative hardness gradient of −1 to −5 Shore C.
2. The golf ball of claim 1 , wherein the positive hardness gradient is greater than 25 Shore C.
3. The golf ball of claim 2 , wherein the positive hardness gradient is greater than 30 Shore C.
4. The golf ball of claim 1 , wherein the resorcinol is present in an amount of about 0.1 pph to about 1.0 pph.
5. The golf ball of claim 1 , wherein the hardness of the first outer surface is 85 Shore C to 95 Shore C and the hardness of the geometric center is 50 Shore C to 60 Shore C.
6. The golf ball of claim 1 , wherein the hardness of the second outer surface is 65 Shore C to 70 Shore C and the hardness of the inner surface is 67 Shore C to 72 Shore C.
7. The golf ball of claim 1 , wherein the inner surface hardness is greater than the hardness of the geometric center and less than the hardness of the first outer surface.
8. The golf ball of claim 1 , wherein the second composition comprises an antioxidant in an amount of about 0.1 pph to about 1.0 pph.
9. The golf ball of claim 1 , wherein the cover layer comprises an inner cover layer and an outer cover layer.
10. A golf ball comprising:
an inner core having a first outer surface and a geometric center and being formed from a first substantially homogenous rubber composition throughout, the rubber composition comprising a base rubber and a resorcinol such that the geometric center has a hardness of 40 to 60 Shore C and the first outer surface has a hardness of 70 or greater;
an outer core layer disposed about the inner core, the outer core layer having a second outer surface having a hardness of 50 to 75 Shore C and an inner surface having a hardness of 56 to 80 Shore C and being formed from a second substantially homogenous formulation throughout; and
a cover layer disposed about the outer core layer;
wherein the geometric center, the first and second outer surfaces, and the inner surface each have a hardness, the hardness of the first outer surface being greater than the hardness of the geometric center to define a positive hardness gradient of greater than 20 Shore C, and the hardness of the second outer surface being lower than the hardness of the inner surface to define a negative hardness gradient of −6 Shore C or greater.
11. The golf ball of claim 10 , wherein the positive hardness gradient is greater than 25 Shore C.
12. The golf ball of claim 11 , wherein the positive hardness gradient is greater than 30 Shore C.
13. The golf ball of claim 10 , wherein the resorcinol is present in an amount of about 0.1 pph to about 1.0 pph.
14. The golf ball of claim 10 , wherein the hardness of the first outer surface is 85 Shore C to 95 Shore C and the hardness of the geometric center is 50 Shore C to 60 Shore C.
15. The golf ball of claim 10 , wherein the hardness of the second outer surface is 65 Shore C to 70 Shore C and the hardness of the inner surface is 72 Shore C to 77 Shore C.
16. The golf ball of claim 10 , wherein the inner surface hardness is greater than the hardness of the geometric center and less than the hardness of the first outer surface.
17. The golf ball of claim 10 , wherein the negative hardness gradient is −6 to −15 Shore C.
18. The golf ball of claim 17 , wherein negative hardness gradient is −8 to −12 Shore C.
19. The golf ball of claim 10 , wherein the second composition comprises an antioxidant in an amount of about 0.1 pph to about 1.0 pph.
20. The golf ball of claim 10 , wherein the cover layer comprises an inner cover layer and an outer cover layer.