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 1.62 inches and consists of:
(a) a center having a diameter of from 0.125 inches to 0.750 inches;
(b) an intermediate core layer formed from a first highly neutralized polymer composition; and
(c) an outer core layer formed from a second highly neutralized polymer composition;
wherein the material hardness of the first highly neutralized polymer composition is less than the material hardness of the second highly neutralized polymer composition;
wherein the intermediate core layer has a surface hardness less than the surface hardness of the center and the surface hardness of the outer core layer; 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;
an alkyl acrylate rubber selected from ethylene-alkyl acrylates and ethylene-alkyl methacrylates;
magnesium oleate present in an amount of 20 parts or greater per 100 parts of acid copolymer and akyl acrylate rubber combined; and
a cation source present in an amount sufficient to neutralize 110% or greater of all acid groups present in the composition.
2. The golf ball of claim 1 , wherein the surface hardness of the center is 65 Shore C or greater.
3. The golf ball of claim 1 , wherein the surface hardness of the center is 70 Shore C or greater.
4. The golf ball of claim 1 , wherein the surface hardness of the intermediate core layer is from 20 Shore C to 70 Shore C.
5. The golf ball of claim 1 , wherein the surface hardness of the outer core layer is from 80 Shore C to 90 Shore C.
6. The golf ball of claim 1 , wherein the outer core layer has a thickness of from 0.010 inches to 0.150 inches.
7. The golf ball of claim 1 , wherein the outer core layer has a thickness of from 0.030 inches to 0.070 inches.
8. The golf ball of claim 1 , wherein the center is formed from a rubber composition.
9. The golf ball of claim 1 , wherein the center is formed from a thermoplastic composition.