# US 7,744,491 B2 · Multilayer golf ball with a thin thermoset outer layer

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- Number: US 7,744,491 B2
- Document ID: US7744491B2
- Status: Granted
- Kind: B2
- Application number: 12/071,684
- Filed: 2008-02-25
- Published: 2008-06-19
- Granted: 2010-06-29
- Earliest claimed: 1997-05-27
- Assignees: Acushnet Company
- Inventors: Edmund A. Hebert; Christopher Cavallaro
- Web page: https://patentgrep.com/patent/US7744491B2

## CPC

- B29D 99/0042: {Producing plain balls (hollow balls B29D22/04)}
- A63B 37/0003: {Golf balls}
- A63B 37/0049: {Flexural modulus; Bending stiffness}
- A63B 37/0076: {Multi-piece balls, i.e. having two or more intermediate layers}
- A63B 37/00922: {whereby hardness of the cover is lower than hardness of the intermediate layers}
- C08L 23/08: Copolymers of ethene (C08L23/16 takes precedence)
- A63B 37/0031: {Hardness}
- A63B 37/0043: {Hardness}
- A63B 37/0064: {Diameter}
- A63B 37/12: Special coverings {, i.e. outer layer material (balls with finger holes A63B37/0001, golf ball covers A63B37/0023)}
- B29C 35/02: Heating or curing, e.g. crosslinking or vulcanizing {during moulding, e.g. in a mould}(cold vulcanisation B29C35/18 {; vulcanising tyres, presses therefor B29D30/0601})
- B29C 39/00: Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor (B29C41/00 takes precedence)
- B29C 45/00: Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor (injection blow-moulding B29C49/06)
- B29L 2031/54: Balls
- C08L 23/0876: Salts thereof, i.e. ionomers
- C08L 2205/02: containing two or more polymers of the same C08L -group
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- 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)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

The present invention is directed towards a method of forming a multilayer golf ball which comprises a core, an inner cover layer and an outer cover layer. The steps include forming a golf ball core; molding an inner cover layer around said golf ball core with a material having a first shore D hardness; and casting an outer cover layer around said inner cover layer and golf ball core with a thermoset material having a second shore D hardness less than the first. The core is comprised of a center made from a first rubber based material and an outer layer formed from a second rubber based material. Preferably, the first rubber based material has about 15 to 25 parts of a crosslinking agent per hundred parts of rubber and the second rubber based material has about 20 to 40 parts of a crosslinking agent per hundred parts of rubber.

## Claims

### Claim 1

A golf ball comprising:
a center comprising a first resilient rubber-based component comprising a first base rubber and a first crosslinking agent, wherein the first crosslinking agent is present in an first amount;
an outer core layer disposed about the center to form a core comprising a second resilient rubber-based component comprising a second base rubber and a second crosslinking agent, wherein the second crosslinking agent is present in an second amount of about 30 to about 38 parts per hundred parts of the second base rubber, wherein the second amount is greater than the first amount by at least about 5 parts per hundred, and wherein the second resilient rubber-based component has different physical properties than the first resilient rubber-based component;
an inner cover layer disposed about the core comprising a material having a first Shore D hardness; and
an outer cover layer disposed about the inner cover layer formed from a castable reactive liquid material and having a second Shore D hardness less than the first Shore D hardness.

### Claim 2 (depends on 1)

The golf ball of claim 1, wherein the second Shore D hardness is from about 30 to about 60 Shore D, and wherein the first Shore D hardness is from about 65 to about 80 Shore D.

### Claim 3 (depends on 1)

The golf ball of claim 1, wherein the first amount is from about 15 to about 25 parts per hundred parts of the first base rubber.

### Claim 4 (depends on 1)

The golf ball of claim 1, wherein the inner cover layer comprises an ionomer resin.

### Claim 5 (depends on 4)

The golf ball of claim 4, wherein the ionomer resin comprises at least about 16 percent by weight acrylic or methacrylic acid.

### Claim 6 (depends on 1)

The golf ball of claim 1, wherein the castable reactive liquid material comprises thermo set polyurethane, thermoset urethane ionomer, or thermoset urethane epoxies.

### Claim 7 (depends on 1)

The golf ball of claim 1, wherein the outer core layer comprises a plurality of layers.

### Claim 8

A golf ball comprising:
a center comprising a first resilient rubber-based component comprising a first base rubber and a first crosslinking agent present in a first amount of about 15 to about 25 parts per hundred parts of the first base rubber;
an outer core layer disposed about the center to form a core comprising a second resilient rubber-based component comprising a second base rubber and a second crosslinking agent present in a second amount of about 30 to about 38 parts per hundred parts of the second base rubber, wherein the second amount is greater than the first amount by at least about 5 parts per hundred;
an inner cover layer disposed about the core having a hardness of about 65 to about 80 Shore D; and
an outer cover layer disposed about the inner cover layer having a hardness from about 30 to about 60 Shore D.

### Claim 9 (depends on 8)

The golf ball of claim 8, wherein the outer cover layer is cast from thermoset polyurethane, thermoset polyurethane ionomer, or thermoset polyurethane epoxy.

### Claim 10 (depends on 8)

The golf ball of claim 8, wherein the inner cover layer comprises ionomer resin.

### Claim 11 (depends on 10)

The golf ball of claim 10, wherein the ionomer resin comprises an E/X/Y copolymer, wherein E is ethylene, X is softening comonomer, and Y is acrylic or methacrylic acid, wherein Y is present in an amount at least about 16 percent by weight of the E/X/Y copolymer.

### Claim 12 (depends on 8)

The golf ball of claim 8, wherein the inner cover layer has a hardness of about 68 to about 72 Shore D.

### Claim 13 (depends on 12)

The golf ball of claim 12, wherein the first and second resilient rubber-based components have different physical properties.

### Claim 14 (depends on 8)

The golf ball of claim 8, wherein the outer core layer comprises a plurality of layers.

### Claim 15

A golf ball comprising:
a center comprising a first resilient rubber-based component comprising a first base rubber and a first crosslinking agent, wherein the first crosslinking agent is present in a first amount;
an outer core layer disposed about the center to form a core comprising a second resilient rubber-based component comprising a second base rubber and a second crosslinking agent, wherein the second crosslinking agent is present in a second amount that is greater than the first amount by at least about 5 parts per hundred, wherein the second amount is from about 30 to about 38 parts per hundred parts of the second base rubber, and wherein the second resilient rubber-based component has different physical properties than the first resilient rubber-based component;
an inner cover layer disposed about the core comprising a material having a first Shore D hardness and a flexural modulus of at least about 65,000 psi, wherein the inner cover layer comprises an ionomer resin comprises at least about 16 percent acrylic or methacrylic acid; and
an outer cover layer disposed about the inner cover layer formed from castable reactive liquid material and having a second Shore D hardness less than the first Shore D hardness.

### Claim 16 (depends on 15)

The golf ball of claim 15, wherein the castable reactive liquid material comprises thermoset polyurethane.

### Claim 17 (depends on 15)

The golf ball of claim 15, wherein the inner cover layer material has a flexural modulus of at least about 75,000 psi.

### Claim 18 (depends on 15)

The golf ball of claim 15, wherein the first amount is about 15 to about 25 parts per hundred of the first base rubber.

### Claim 19 (depends on 15)

The golf ball of claim 15, wherein the first Shore D hardness is about 65 to about 80 Shore D and the second Shore D hardness is about 30 to about 60 Shore D.

### Claim 20 (depends on 15)

The golf ball of claim 15, wherein the outer core layer comprises a plurality of layers.