Multi-layer golf ball
The present invention is directed to multi-layer golf balls including a layer formed from a composition comprising a relatively soft or low modulus HNP, a layer formed from a composition comprising a relatively hard or high modulus HNP, an inner cover layer formed from a thermoplastic composition, and an outer cover layer.
1. A golf ball comprising:
(a) an inner core layer formed from a first composition, the first 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;
(b) an outer core layer formed from a second composition, the second 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; and
(c) a cover;
wherein the Shore D hardness of the first composition is greater than the Shore D hardness of the second composition; and
wherein the second composition has a modulus of from 1,000 psi to 50,000 psi, the first composition has a modulus of 150,000 psi or less, and the modulus of the second composition is at least 10% less than the modulus of the first composition.
2. The golf ball of claim 1 , wherein the Shore D hardness of the second composition is from 10 to 60.
3. The golf ball of claim 1 , wherein the Shore D hardness of the second composition is from 20 to 55.
4. The golf ball of claim 1 , wherein the Shore D hardness of the first composition is from 35 to 80.
5. The golf ball of claim 1 , wherein the Shore D hardness of the second composition is at least 3 less than the Shore D hardness of the first composition.