Golf balls having at least two core layers formed from HNP compositions
The present invention is directed to golf balls consisting of a multi-layer core and a cover. The multi-layer core includes at least one layer formed from a relatively soft or low modulus HNP composition and at least one layer formed from a relatively hard or high modulus HNP composition.
1. A golf ball comprising a core and a cover, wherein the core has an overall diameter of from 1.40 inches to 1.60 inches and consists of:
(a) a center having a diameter of from 0.50 inches to 1.50 inches and a center hardness (H) of from 20 Shore C to 90 Shore C;
(b) an intermediate core layer having a surface hardness (I) of 40 Shore C or greater and formed from a first highly neutralized polymer composition; and
(c) an outer core layer having a surface hardness (S) of from 20 Shore C to 90 Shore C and formed from a second highly neutralized polymer composition;
wherein H<I and S<I;
wherein S<H, and wherein H−S=D, where D is an integer from 1 to 22;
wherein the material hardness of the second highly neutralized polymer composition is less than the material hardness of the first highly neutralized polymer composition; and
wherein at least one of the first highly neutralized polymer composition and the second highly neutralized polymer composition comprises:
an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid, optionally including a softening monomer selected from the group consisting of alkyl acrylates and methacrylates;
a non-acid polymer selected from polyethylene butyl acrylate, polyethylene methyl acrylate, and polyethylene ethyl acrylate;
an organic acid or salt thereof; and
a cation source present in an amount sufficient to neutralize greater than 80% of all acid groups present in the composition;
wherein the non-acid polymer is present in an amount of greater than 50 wt %, based on the combined weight of the acid copolymer and the non-acid polymer.
2. The golf ball of claim 1 , wherein the center hardness (H) is from 20 Shore C to 70 Shore C.
3. The golf ball of claim 1 , wherein the center hardness (H) is from 50 Shore C to 60 Shore C.
4. The golf ball of claim 1 , wherein the intermediate core layer surface hardness (I) is from 80 Shore C to 90 Shore C.
5. The golf ball of claim 1 , wherein the outer core layer has a thickness of from 0.010 inches to 0.150 inches.
6. The golf ball of claim 1 , wherein the outer core layer surface hardness (S) is from 20 Shore C to 70 Shore C.
7. The golf ball of claim 1 , wherein the outer core layer surface hardness (S) is from 50 Shore C to 60 Shore C.
8. The golf ball of claim 1 , wherein the outer core layer has a thickness of from 0.030 inches to 0.070 inches.
9. The golf ball of claim 1 , wherein the center is formed from a rubber composition.
10. The golf ball of claim 1 , wherein the center is formed from a thermoplastic composition.