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 50 to 60 Shore C and the outer surface has a hardness of 85 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 such that the geometric center has a hardness of about 50 to 60 Shore C and the first outer surface has a hardness of about 85 to 95 Shore C;
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 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.
5. 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.
6. 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.
7. The golf ball of claim 1 , wherein the cover layer comprises an inner cover layer and an outer cover layer.
8. 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 such that the geometric center has a hardness of about 50 to 60 Shore C and the first outer surface has a hardness of about 85 to 95 Shore C;
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.
9. The golf ball of claim 8 , wherein the positive hardness gradient is greater than 25 Shore C.
10. The golf ball of claim 9 , wherein the positive hardness gradient is greater than 30 Shore C.
11. The golf ball of claim 8 , 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.
12. The golf ball of claim 8 , wherein the inner surface hardness is greater than the hardness of the geometric center and less than the hardness of the first outer surface.
13. The golf ball of claim 8 , wherein the negative hardness gradient is −6 to −15 Shore C.
14. The golf ball of claim 13 , wherein negative hardness gradient is −8 to −12 Shore C.
15. The golf ball of claim 8 , wherein the second composition comprises an antioxidant in an amount of about 0.1 pph to about 1.0 pph.
16. The golf ball of claim 8 , wherein the cover layer comprises an inner cover layer and an outer cover layer.