# US 8,465,381 B2 · Three-layer-core golf ball having highly-neutralized polymer outer core layer

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- Number: US 8,465,381 B2
- Document ID: US8465381B2
- Status: Granted
- Kind: B2
- Application number: 13/416,132
- Filed: 2012-03-09
- Published: 2012-10-04
- Granted: 2013-06-18
- Earliest claimed: 2001-06-26
- Assignees: Acushnet Company
- Applicants: Murali Rajagopalan; Michael J. Sullivan
- Inventors: Murali Rajagopalan; Michael J. Sullivan
- Web page: https://patentgrep.com/patent/US8465381B2

## CPC

- A63B 37/0039: {characterised by the material}
- A63B 37/0043: {Hardness}
- A63B 37/0045: {Thickness}
- A63B 37/0049: {Flexural modulus; Bending stiffness}
- A63B 37/00622: {Surface hardness}
- A63B 37/0064: {Diameter}
- A63B 37/0065: {Deflection or compression}
- A63B 37/0076: {Multi-piece balls, i.e. having two or more intermediate layers}
- A63B 37/0092: {Hardness distribution amongst different ball layers}
- C08L 23/08: Copolymers of ethene (C08L23/16 takes precedence)
- A63B 37/0031: {Hardness}
- A63B 37/0033: {Thickness}
- A63B 37/0047: {Density; Specific gravity}
- A63B 37/0066: {Density; Specific gravity}
- C08L 23/0876: Salts thereof, i.e. ionomers
- C08L 2205/02: containing two or more polymers of the same C08L -group
- Y10T 428/24983: Hardness
- A63B: APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT (apparatus for passive exercising, massage A61H)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A golf ball including an inner core layer formed from a thermoset rubber composition and having a first surface hardness; a thermoplastic outer core layer having a second surface hardness, an inner surface hardness, and being formed from a copolymer of ethylene and an α,β-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to fully-neutralize the acid groups of the copolymer; an inner cover layer; and an outer cover layer; wherein the first surface hardness is substantially the same as the second surface hardness and the inner surface hardness.

## Claims

### Claim 1

A golf ball comprising:
an inner core layer comprising a thermoset rubber composition and having a first outer Shore D hardness and an outer diameter of about 1.3 inches to about 1.56 inches;
a thermoplastic outer core layer having a second outer Shore D hardness, and comprising a copolymer of ethylene and an α,β-unsaturated carboxylic acid, a magnesium salt of oleic acid, and sufficient cation source to fully-neutralize the acid groups of the copolymer;
an inner cover layer; and
an outer cover layer;
wherein the first outer hardness is greater than the second outer hardness and the outer core layer has a thickness of about 0.01 inches to about 0.05 inches.

### Claim 2 (depends on 1)

The golf ball of claim 1, wherein the inner core has a diameter of about 1.4 inches to about 1.55 inches.

### Claim 3 (depends on 1)

The golf ball of claim 1, wherein the outer core layer has a thickness of about 0.02 inches to about 0.04 inches.

### Claim 4 (depends on 1)

The golf ball of claim 1, wherein the cation source is selected from a group consisting of metal cations of lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, and aluminum.

### Claim 5 (depends on 1)

The golf ball of claim 1, wherein the first outer surface hardness is about 46 Shore D to about 60 Shore D.

### Claim 6 (depends on 5)

The golf ball of claim 5, wherein the first outer surface hardness is about 49 Shore D to about 55 Shore D.

### Claim 7 (depends on 1)

The golf ball of claim 1, wherein the second outer surface hardness is about 40 Shore D to about 54 Shore D.

### Claim 8 (depends on 7)

The golf ball of claim 7, wherein the second outer surface hardness is about 45 Shore D to about 51 Shore D.

### Claim 9 (depends on 1)

The golf ball of claim 1, wherein the inner cover layer comprises an ionomer and the outer cover layer comprises a cast polyurethane.