Multi-layer golf ball
The present invention is directed to multi-layer golf balls including a layer formed from a relatively soft or low modulus HNP composition and a layer formed from a relatively hard or high modulus HNP composition. Optionally, the soft (or low modulus) HNP composition and/or the hard (or high modulus) HNP composition is plasticized or is replaced with a different plasticized acid copolymer composition.
1. A golf ball comprising:
(a) an inner core layer formed from a first composition, the first composition having a Shore D hardness of 65 or less and comprising an ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer wherein 40% to 100% of the acid groups of the acid copolymer are neutralized;
(b) an outer core layer formed from a second composition, the second composition having a Shore D hardness of 35 or greater and comprising a highly neutralized ethylene/(meth)acrylic acid copolymer wherein from 40% to 100% of the acid groups of the acid copolymer are neutralized; and
(c) a cover;
wherein the Shore D hardness of the first composition is less than the Shore D hardness of the second composition.
2. The golf ball of claim 1 , wherein the Shore D hardness of the first composition is from 10 to 60.
3. The golf ball of claim 1 , wherein the Shore D hardness of the first composition is from 20 to 55.
4. The golf ball of claim 1 , wherein the Shore D hardness of the first composition is from 30 to 50.
5. The golf ball of claim 1 , wherein the Shore D hardness of the second composition is from 35 to 80.
6. The golf ball of claim 1 , wherein the Shore D hardness of the second composition is from 45 to 75.
7. The golf ball of claim 1 , wherein the Shore D hardness of the first composition is at least 3 less than the Shore D hardness of the second composition.
8. The golf ball of claim 1 , wherein the first composition has a modulus of from 1,000 psi to 50,000 psi.
9. The golf ball of claim 1 , wherein the second composition has a modulus of 150,000 psi or less.
10. The golf ball of claim 1 , wherein the first composition has a modulus of from 1,000 psi to 50,000 psi, the second composition has a modulus of 150,000 psi or less, and the modulus of the first composition is at least 10% less than the modulus of the second composition.
11. The golf ball of claim 10 , wherein the modulus of the first composition is at least 25% less than the modulus of the second composition.
12. The golf ball of claim 1 , wherein the golf ball additionally comprises an intermediate core layer disposed between the inner core layer and the outer core layer, wherein the intermediate core layer is formed from a diene rubber composition.