Thermoplastic dual core having a negative gradient inner core and a positive gradient outer core

Patent metadata

Field	Value
Publication number	US-9789367-B2
Application number	US-201514978162-A
Country	US
Kind code	B2
Filing date	Dec 22, 2015
Priority date	Nov 14, 2007
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A golf ball including a thermoplastic inner core layer that has a geometric center hardness greater than its surface hardness to define a negative hardness gradient. An outer core layer is disposed about the inner core and is formed from a thermoplastic material and has an inner surface hardness substantially less than its outer surface hardness to define a positive hardness gradient. An inner cover layer is disposed about the outer core layer and an outer cover layer is disposed about the inner cover layer.

First claim

What is claimed is:

1. A golf ball comprising:
an inner core layer comprising a first thermoplastic material and having a geometric center hardness greater than a surface hardness to define a negative hardness gradient, wherein the inner core surface hardness is about 40 Shore C to about 60 Shore C;
an outer core layer disposed about the inner core, the outer core layer comprising a second thermoplastic material and having an inner surface hardness substantially less than an outer surface hardness to define a positive hardness gradient;
an inner cover layer disposed outer core layer; and
an outer cover layer disposed about the inner cover layer.

2. The golf ball of claim 1 , wherein the first and second thermoplastic materials comprise an ionomer, a highly-neutralized ionomer, a thermoplastic polyurethane, a thermoplastic polyurea, a styrene block copolymer, a polyester amide, polyester ether, a polyethylene acrylic acid copolymer or terpolymer, or a polyethylene methacrylic acid copolymer or terpolymer.

3. The golf ball of claim 1 , wherein the difference between the inner core surface hardness and the outer core inner surface hardness is 25 Shore C to 45 Shore C.

4. The golf ball of claim 3 , wherein the difference between the inner core surface hardness and the outer core inner surface hardness is 30 Shore C to 35 Shore C.

5. The golf ball of claim 1 , wherein the outer core surface hardness is about 65 Shore C to about 100 Shore C.

6. The golf ball of claim 5 , wherein the outer core surface hardness is about 75 Shore C to about 95 Shore C.

7. The golf ball of claim 1 , wherein the outer core layer comprises a gradient-promoting additive.

8. A golf ball comprising:
an inner core layer comprising a first thermoplastic material and having a geometric center hardness greater than a surface hardness to define a negative hardness gradient between −1 Shore C and −5 Shore C;
an outer core layer disposed about the inner core layer, the outer core layer comprising a second thermoplastic material and having an inner surface hardness less than an outer surface hardness to define a substantially positive hardness gradient of at least 5 Shore C; and
a cover layer disposed outer core layer, the cover layer comprising an inner cover layer comprising an ionomer and an outer cover layer comprising a castable polyurethane or polyurea material.

9. A golf ball comprising:
an inner core layer comprising a first thermoplastic material and having a geometric center hardness greater than a surface hardness to define a negative hardness gradient between −1 Shore C and −5 Shore C, the center hardness being about 25 Shore C to about 50 Shore C and the surface hardness being about 20 Shore C to about 47 Shore C;
an outer core layer disposed about the inner core layer, the outer core layer comprising a second thermoplastic material and having an inner surface hardness less than an outer surface hardness to define a positive hardness gradient of at least 5 Shore C; and
a cover layer disposed outer core layer, the cover layer comprising an inner cover layer comprising an ionomer and an outer cover layer comprising a castable polyurethane or polyurea material.

Assignees

• Acushnet Co

Inventors

• Sullivan Michael J
• Comeau Brian
• Lacy William B

Classifications

• A63B37/0059

  Ionomer · CPC title

• A63B37/0039

  characterised by the material · CPC title

• A63B37/0043

  Hardness · CPC title

• B29K2023/00

  Use of polyalkenes {or derivatives thereof} as moulding material · CPC title

• C08K5/09

  Carboxylic acids; Metal salts thereof; Anhydrides thereof · CPC title