Three-layer-core golf ball having highly-neutralized polymer outer core layer
View Patent ↗A golf ball includes an inner core layer formed from a thermoset rubber composition. The inner core layer has a first outer surface Shore D hardness and an outer diameter of about 1.0 to 1.6 inches. A thermoplastic outer core layer is formed around the inner core layer, has a second outer surface Shore D hardness, and is formed from an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid, optionally including a softening monomer, such as alkyl acrylates and methacrylates; a plasticizer; and a cation source present in an amount sufficient to neutralize about 70 to 100% of the acid groups present in the material. The golf ball an inner and outer cover layers. The second outer surface Shore D hardness is greater than the first outer surface Shore D hardness.
1. A golf ball comprising:
an inner core layer comprising a thermoset rubber composition and having a first outer surface Shore D hardness and an outer diameter of about 1.0 inch to about 1.6 inches;
an outer core layer having a thickness of about 0.02 inches to about 0.15 inches and a second outer surface Shore D hardness greater than the first;
an inner cover layer; and
an outer cover layer;
wherein the outer core layer comprises a thermoplastic material comprising:
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 plasticizer; and
a cation source present in an amount sufficient to neutralize from about 80% to about 100% of all acid groups present in the material.
2. The golf ball of claim 1 , wherein the first outer surface hardness is about 30 Shore D to about 65 Shore D and the second outer surface hardness is about 35 Shore D to about 70 Shore D.
3. The golf ball of claim 2 , wherein the first outer surface hardness is about 35 Shore D to about 60 Shore D and the second outer surface hardness is about 40 Shore D to about 65 Shore D.
4. The golf ball of claim 1 , wherein the plasticizer is present in an amount of about 3 to 50% by weight.
5. The golf ball of claim 1 , wherein the plasticizer comprises a fatty acid ester.
6. The golf ball of claim 5 , wherein the plasticizer comprises an alkyl oleate.
7. The golf ball of claim 6 , wherein the alkyl oleate comprises methyl oleate, ethyl oleate, propyl oleate, butyl oleate, octyl oleate, 2-ethylhexyl oleate, or mixtures thereof.
8. The golf ball of claim 7 , wherein the plasticizer comprises butyl oleate or glycerol trioleate.
9. The golf ball of claim 1 , wherein 90% or greater of the acid groups are neutralized.
10. The golf ball of claim 9 , wherein 100% of the acid groups are neutralized.
11. The golf ball of claim 1 , wherein the inner core outer diameter is about 1.2 to 1.58 inches.
12. The golf ball of claim 11 , wherein the inner core outer diameter is about 1.3 to 1.56 inches.
13. The golf ball of claim 1 , wherein the outer core layer thickness is about 0.04 inches to about 0.125 inches.
14. The golf ball of claim 13 , wherein the outer core layer thickness is about 0.05 inches to about 0.095 inches.
15. A golf ball comprising:
an inner core layer comprising a thermoset rubber composition and having a first outer surface Shore D hardness and an outer diameter of about 0.8 inches to about 1.6 inches;
a thermoplastic outer core layer having a second outer surface Shore D hardness, and comprising 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 plasticizer comprising butyl oleate or glycerol trioleate; and a cation source present in an amount sufficient to neutralize from about 80 to about 100% of all acid groups present in the material;
an inner cover layer; and
an outer cover layer;
wherein the first outer surface hardness is about 40 Shore D to about 55 Shore D and the second outer surface hardness is about 45 Shore D to about 60 Shore D, and wherein the outer core layer has a thickness of about 0.02 inches to about 0.150 inches.
16. A golf ball comprising:
an inner core layer comprising a thermoset rubber composition and having a first outer surface Shore D hardness and an outer diameter of about 0.8 inches to about 1.6 inches;
a thermoplastic outer core layer having a second outer surface Shore D hardness, and comprising an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid; a plasticizer comprising butyl oleate or glycerol trioleate; and a cation source present in an amount sufficient to neutralize from about 90 to about 100% of all acid groups present in the material;
an inner cover layer; and
an outer cover layer;
wherein the first outer surface hardness is about 40 Shore D to about 55 Shore D and the second outer surface hardness is about 45 Shore D to about 60 Shore D, and wherein the outer core layer has a thickness of about 0.02 inches to about 0.150 inches.
17. The golf ball of claim 15 , wherein the plasticizer is present in an amount of about 3 to 50% by weight.
18. The golf ball of claim 15 , wherein 90% or greater of the acid groups are neutralized.
19. The golf ball of claim 16 , wherein the plasticizer is present in an amount of about 3 to 50% by weight.
20. The golf ball of claim 16 , wherein 90% or greater of the acid groups are neutralized.