Golf balls having at least one layer formed from a plasticized acid copolymer composition
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) a center having a diameter of from 0.50 inches to 1.30 inches, a center hardness of 50 Shore C or greater, and formed from a composition comprising a first 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;
(b) an outer core layer having a surface hardness of 75 Shore C or greater and formed from a composition comprising a second 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;
(c) an inner cover layer having a material hardness less than the surface hardness of the outer core layer; and
(d) an outer cover layer;
wherein at least one of the center composition and the outer core layer composition is a plasticized composition comprising from 0.5 wt % to 80 wt %, based on the total weight of the composition, of a plasticizer; and
wherein at least one of the center composition and the outer core layer composition is at least partially neutralized such that at least 70% of all acid groups present in the composition are neutralized.
2. The golf ball of claim 1 , wherein the center composition is the plasticized composition and the outer core layer composition is at least partially neutralized.
3. The golf ball of claim 2 , wherein the center composition is at least partially neutralized.
4. The golf ball of claim 3 , wherein the surface hardness of the outer core layer is greater than the surface hardness of the center.
5. The golf ball of claim 1 , wherein the outer core layer composition is the plasticized composition and the center composition is at least partially neutralized.
6. The golf ball of claim 5 , wherein the outer core layer composition is at least partially neutralized.
7. The golf ball of claim 1 , wherein the plasticizer is selected from the group consisting of fatty acid esters.
8. The golf ball of claim 1 , wherein the first acid copolymer is a relatively low modulus HNP, and the second acid copolymer is a relatively high modulus HNP, wherein the modulus of the first acid copolymer is at least 10% less than the modulus of the second copolymer.
9. The golf ball of claim 8 , wherein the modulus of the first acid copolymer is at least 25% less than the modulus of the second copolymer.
10. The golf ball of claim 8 , wherein the center composition is the plasticized composition.
11. A golf ball comprising:
(a) a center having a diameter of from 0.50 inches to 1.30 inches, a center hardness of 75 Shore C or greater, and formed from a composition comprising a first 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;
(b) an outer core layer having a surface hardness of 50 Shore C or greater and formed from a composition comprising a second 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;
(c) an inner cover layer; and
(d) an outer cover layer;
wherein at least one of the center composition and the outer core layer composition is a plasticized composition comprising from 0.5 wt % to 80 wt %, based on the total weight of the composition, of a plasticizer; and
wherein at least one of the center composition and the outer core layer composition is at least partially neutralized such that at least 70% of all acid groups present in the composition are neutralized.
12. The golf ball of claim 11 , wherein the center composition is the plasticized composition and the outer core layer composition is at least partially neutralized.
13. The golf ball of claim 12 , wherein the center composition is at least partially neutralized.
14. The golf ball of claim 13 , wherein the surface hardness of the center is greater than the surface hardness of the outer core layer.
15. The golf ball of claim 11 , wherein the outer core layer composition is the plasticized composition and the center composition is at least partially neutralized.
16. The golf ball of claim 15 , wherein the outer core layer composition is at least partially neutralized.
17. The golf ball of claim 11 , wherein the plasticizer is selected from the group consisting of fatty acid esters.
18. The golf ball of claim 11 , wherein the first acid copolymer is a relatively high modulus HNP, and the second acid copolymer is a relatively low modulus HNP, wherein the modulus of the second acid copolymer is at least 10% less than the modulus of the first copolymer.
19. The golf ball of claim 18 , wherein the modulus of the second acid copolymer is at least 25% less than the modulus of the first copolymer.
20. The golf ball of claim 18 , wherein the outer core layer composition is the plasticized composition.