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 and a layer formed from a composition comprising a relatively hard or high modulus HNP.
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 comprises:
(a) a center having a diameter of from 0.50 inches to 1.50 inches, a surface hardness of 65 Shore C or greater, a center hardness (H), and formed from a highly neutralized polymer composition, the highly neutralized polymer composition having a material hardness of 55 Shore D or less and comprising a highly neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer wherein at least 80% of the acid groups of the acid copolymer are neutralized; and
(b) an outer core layer having a surface hardness (S) of from 20 Shore C to 70 Shore C and formed from a partially neutralized polymer composition, the partially neutralized polymer composition having a material hardness of 45 Shore D or greater and comprising a partially neutralized ethylene/(meth)acrylic acid copolymer wherein 40% to 100% of the acid groups of the acid copolymer are neutralized;
wherein H<S, and wherein S−H=D, where D is an integer from 1 to 22, and
wherein the material hardness of the highly neutralized composition used to form the center is less than the material hardness of the partially neutralized composition used to form the outer core layer.
2. 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 comprises:
(a) a center having a diameter of from 0.50 inches to 1.50 inches, a surface hardness of 65 Shore C or greater, a center hardness (H), and formed from a partially neutralized polymer composition, the partially neutralized polymer composition having a material hardness of 55 Shore D or less and comprising a partially neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer wherein 40% to 100% of the acid groups of the acid copolymer are neutralized; and
(b) an outer core layer having a surface hardness (S) of from 20 Shore C to 70 Shore C and formed from a highly neutralized polymer composition, the highly neutralized polymer composition having a material hardness of 45 Shore D or greater and comprising a highly neutralized ethylene/(meth)acrylic acid copolymer wherein at least 80% of the acid groups of the acid copolymer are neutralized;
wherein H<S, and wherein S−H=D, where D is an integer from 1 to 22, and
wherein the material hardness of the partially neutralized composition used to form the center is less than the material hardness of the highly neutralized composition used to form the outer core layer.
3. 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 comprises:
(a) a center having a diameter of from 0.50 inches to 1.50 inches, a surface hardness of 65 Shore C or greater, a center hardness (H), and formed from a highly neutralized polymer composition, the highly neutralized polymer composition having a material hardness of 45 Shore D or greater and comprising a highly neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer wherein at least 80% of the acid groups of the acid copolymer are neutralized; and
(b) an outer core layer having a surface hardness (S) of from 20 Shore C to 70 Shore C and formed from a partially neutralized polymer composition, the partially neutralized polymer composition having a material hardness of 55 Shore D or less and comprising a partially neutralized ethylene/(meth)acrylic acid copolymer wherein 40% to 100% of the acid groups of the acid copolymer are neutralized;
wherein the material hardness of the highly neutralized composition used to form the center is greater than the material hardness of the partially neutralized composition used to form the outer core layer.
4. The golf ball of claim 3 , wherein H<S, and wherein S−H=D, where D is an integer from 1 to 22.
5. 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 comprises:
(a) a center having a diameter of from 0.50 inches to 1.50 inches, a surface hardness of 65 Shore C or greater, a center hardness (H), and formed from a partially neutralized polymer composition, the partially neutralized polymer composition having a material hardness of 45 Shore D or greater and comprising a partially neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer wherein 40% to 100% of the acid groups of the acid copolymer are neutralized; and
(b) an outer core layer having a surface hardness (S) of from 20 Shore C to 70 Shore C and formed from a highly neutralized polymer composition, the highly neutralized polymer composition having a material hardness of 55 Shore D or less and comprising a highly neutralized ethylene/(meth)acrylic acid copolymer wherein at least 80% of the acid groups of the acid copolymer are neutralized;
wherein H<S, and wherein S−H=D, where D is an integer from 1 to 22, and
wherein the material hardness of the partially neutralized composition used to form the center is greater than the material hardness of the highly neutralized composition used to form the outer core layer.
6. The golf ball of claim 5 , wherein H<S, and wherein S−H=D, where D is an integer from 1 to 22.