# US 9,873,026 B2 · Thermoplastic dual core having positive hardness gradient inner and outer core layers

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- Number: US 9,873,026 B2
- Document ID: US9873026B2
- Status: Granted
- Kind: B2
- Application number: 14/978,131
- Filed: 2015-12-22
- Published: 2016-04-21
- Granted: 2018-01-23
- Earliest claimed: 2007-11-14
- Assignees: Acushnet Company
- Applicants: Acushnet Company
- Inventors: Michael J. Sullivan; Brian Comeau; William B. Lacy
- Web page: https://patentgrep.com/patent/US9873026B2

## CPC

- A63B 37/0092: {Hardness distribution amongst different ball layers}
- A63B 37/0044: {Hardness gradient}
- A63B 37/0051: {Materials other than polybutadienes; Constructional details}
- A63B 37/0059: {Ionomer}
- A63B 37/00621: {Centre hardness}
- A63B 37/00622: {Surface hardness}
- A63B 37/0063: {Hardness gradient}
- A63B 37/0064: {Diameter}
- A63B 37/0076: {Multi-piece balls, i.e. having two or more intermediate layers}
- C08K 5/09: Carboxylic acids; Metal salts thereof; Anhydrides thereof
- C08K 5/098: Metal salts of carboxylic acids
- C08L 23/08: Copolymers of ethene (C08L23/16 takes precedence)
- A63B 37/0039: {characterised by the material}
- A63B 37/0043: {Hardness}
- A63B: APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT (apparatus for passive exercising, massage A61H)
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

A golf ball includes an inner core layer including a thermoplastic highly-neutralized ionomer formed from a copolymer of ethylene and an α,β-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to neutralize the acid groups of the copolymer by 80% or greater. The inner core has a geometric center hardness and a surface hardness to define a first positive hardness gradient having a first slope, S1. An outer core layer is disposed about the inner core and is formed from a second thermoplastic highly-neutralized ionomer. The outer core layer has an interior hardness and an outer surface hardness greater than the interior hardness to define a second positive hardness gradient having a second slope, S2. The golf ball also includes a cover layer.

## Claims

### Claim 1

A golf ball comprising:
an inner core layer comprising a first thermoplastic highly-neutralized ionomer comprising a copolymer of ethylene and an α,β-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to neutralize the acid groups of the copolymer by 80% or greater, and having a geometric center hardness and a surface hardness greater than the geometric hardness to define a first hardness positive gradient having a first slope, S1;
an outer core layer disposed about the inner core, the outer core comprising a second thermoplastic highly-neutralized ionomer comprising a copolymer of ethylene and an α,β-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to neutralize the acid groups of the copolymer by 80% or greater, and having an interior hardness and an outer surface hardness greater than the interior hardness to define a second positive hardness gradient having a second slope, S2; and
an outer cover layer;
wherein the ratio of S2 to S1 is about 3.0 or greater.

### Claim 2 (depends on 1)

The golf ball of claim 1, wherein the inner core layer has an outer diameter of about 0.5 inches to about 1.13 inches.

### Claim 3 (depends on 1)

The golf ball of claim 1, wherein the acid groups of the copolymer of the first or second thermoplastic highly-neutralized ionomer are neutralized by 90% or greater.

### Claim 4 (depends on 3)

The golf ball of claim 3, wherein the acid groups of the copolymer of the first or second thermoplastic highly-neutralized ionomer are neutralized by about 100%.

### Claim 5 (depends on 1)

The golf ball of claim 1, wherein the organic acid or salt thereof of the first or second thermoplastic highly-neutralized ionomer comprises barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, or calcium salts, or salts of fatty acids.

### Claim 6 (depends on 5)

The golf ball of claim 5, wherein the fatty acid salt comprises stearic acid, behenic acid, erucic acid, oleic acid, linoelic acid or dimerized derivatives thereof.

### Claim 7 (depends on 6)

The golf ball of claim 6, wherein the organic acid or salt thereof comprises a magnesium salt of oleic acid.

### Claim 8 (depends on 1)

The golf ball of claim 1, wherein the inner core layer or outer core layer comprise a second polymer selected from the group consisting of a partially-neutralized ionomer and an acid copolymer.

### Claim 9 (depends on 1)

The golf ball of claim 1, wherein an angle, θ, is about 90° or greater, wherein θ is defined by the equation:
θ
=
180
-
(
180
π
⁢
(
tan
-
1
⁡
(
S
2
)
-
tan
-
1
⁡
(
S
1
)
)
)
.

### Claim 10 (depends on 9)

The golf ball of claim 9, wherein θ is about 100° or greater.

### Claim 11 (depends on 10)

The golf ball of claim 10, wherein θ is about 110° or greater.

### Claim 12 (depends on 11)

The golf ball of claim 11, wherein θ is about 120° or greater.

### Claim 13 (depends on 1)

The golf ball of claim 1, further comprising an inner cover layer disposed between the outer cover layer and the outer core layer.

### Claim 14

A golf ball comprising:
an inner core layer comprising a first thermoplastic highly-neutralized ionomer comprising a copolymer of ethylene and an α,β-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to neutralize the acid groups of the copolymer by 90% or greater, and having a geometric center hardness and a surface hardness greater than the geometric hardness to define a first hardness positive gradient having a first slope, S1;
an outer core layer disposed about the inner core, the outer core comprising a second thermoplastic highly-neutralized ionomer comprising a copolymer of ethylene and an α,β-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to neutralize the acid groups of the copolymer by 90% or greater, and having an interior hardness and an outer surface hardness greater than the interior hardness to define a second positive hardness gradient having a second slope, S2; and
an outer cover layer;
wherein an angle, θ, is about 90° or greater, wherein θ is defined by the equation:
θ
=
180
-
(
180
π
⁢
(
tan
-
1
⁡
(
S
2
)
-
tan
-
1
⁡
(
S
1
)
)
)
.

### Claim 15 (depends on 14)

The golf ball of claim 14, wherein θ is about 100° or greater.

### Claim 16 (depends on 15)

The golf ball of claim 15, wherein θ is about 110° or greater.

### Claim 17 (depends on 16)

The golf ball of claim 16, wherein θ is about 120° or greater.

### Claim 18 (depends on 14)

The golf ball of claim 14, wherein a ratio of S2 to S1 is about 1.0 or greater.