HIGHLY-NEUTRALIZED THERMOPLASTIC COPOLYMER CENTER FOR IMPROVED MULTI-LAYER CORE GOLF BALL
A golf ball includes a core formed from a thermosetting rubber composition; a cover; and an intermediate layer disposed between the core and the cover. The intermediate layer is formed from a highly-neutralized thermoplastic copolymer of ethylene and an α,β-unsaturated carboxylic acid, the acid being neutralized by a salt of an organic acid or a suitable base of the organic acid, and sufficient cation source to bring the neutralization to 80% or greater. A sphere resulting from a combination of the core and the intermediate layer has an Atti compression of 60 or greater.
1 . A golf ball comprising:
a core having a compression of from 50 to 90, a diameter of from 0.50 inches to 1.55 inches, and formed from a composition comprising:
an E/X/Y-type copolymer of ethylene, an α,β-unsaturated carboxylic acid, and a softening comonomer present in an amount of from 17 wt % to 40 wt % of the polymer;
an organic acid or salt thereof; and
a cation source present in an amount sufficient to neutralize greater than 80% of the acid groups of the copolymer;
an intermediate layer having a thickness of from 0.05 inches to 0.30 inches; and
an outer cover layer having a thickness of from 0.01 inches to 0.10 inches and formed from a composition selected from the group consisting of ionomeric copolymers and terpolymers, ionomer precursors, thermoplastics, thermoplastic elastomers, grafted metallocene-catalyzed polymers, non-grafted metallocene-catalyzed polymers, single-site polymers, high-crystalline acid polymers and their ionomers, cationic ionomers, polyurethanes, polyureas, epoxy resins, polyethylenes, polyamides, polyesters, polycarbonates, and copolymers comprising urethane and urea segments;
wherein the specific gravity of the core differs from the specific gravity of the intermediate layer by at least 0.1.
2 . The golf ball of claim 1 , wherein the cation source is present in an amount sufficient to neutralize from 90% to 100% of the acid groups of the copolymer.
3 . The golf ball of claim 1 , wherein the cation source is present in an amount sufficient to neutralize 100% of the acid groups of the copolymer.
4 . The golf ball of claim 1 , wherein the core has a compression of 80 or greater.
5 . The golf ball of claim 1 , wherein the thickness of the intermediate layer is from 0.09 inches to 0.18 inches.
6 . The golf ball of claim 1 , wherein the thickness of the outer cover layer is from 0.02 inches to 0.06 inches.
7 . The golf ball of claim 1 , wherein the golf ball additionally comprises an inner cover layer.
8 . The golf ball of claim 7 , wherein the inner cover layer is formed from a composition having a Shore D hardness of at least 60.
9 . The golf ball of claim 1 , wherein the outer cover layer is formed from a thermoset polyurethane composition.
10 . The golf ball of claim 9 , wherein the outer cover layer composition has a Shore D hardness of from 45 to 60.
11 . The golf ball of claim 9 , wherein the thermoset polyurethane composition is a castable reactive liquid material.
12 . The golf ball of claim 1 , wherein the diameter of the core is 1.50 inches or less.
13 . The golf ball of claim 1 , wherein the diameter of the core is from 0.80 inches to 1.40 inches.