Medium gradient dual core golf ball

• US 9,669,267 B2
• Filed: 07/08/2015
• Issued: 06/06/2017
• Est. Priority Date: 11/28/2001
• Status: Expired due to Term

• Current Assignee: Acushnet Company (FILA Holdings Corp.)
• Original Assignee: Acushnet Company (FILA Holdings Corp.)
• Inventors: Sullivan, Michael J., Comeau, Brian, Britton, Dennis
• Primary Examiner(s): Gorden, Raeann
• Application Number:
  US14/794,019
• Publication Number:
  US 20150306466A1
• Time in Patent Office: 699 Days
• Field of Search: 473376
• CPC Class Codes: A63B 37/0003 Golf balls
• CPC Class Codes: A63B 37/0027 Polyurea
• CPC Class Codes: A63B 37/0039 characterised by the material
• CPC Class Codes: A63B 37/0043 Hardness
• CPC Class Codes: A63B 37/0044 Hardness gradient
• CPC Class Codes: A63B 37/00621 Centre hardness
• CPC Class Codes: A63B 37/00622 Surface hardness
• CPC Class Codes: A63B 37/0063 Hardness gradient
• CPC Class Codes: A63B 37/0064 Diameter
• CPC Class Codes: A63B 37/0066 Density; Specific gravity
• CPC Class Codes: A63B 37/0075 Three piece balls, i.e. cover, intermediate layer and core
• CPC Class Codes: A63B 37/0076 Multi-piece balls, i.e. having two or more intermediate layers
• CPC Class Codes: A63B 37/0092 Hardness distribution amongst different ball layers
• CPC Class Codes: A63B 37/02 Special cores balls with finger holes A63B37/0001, golf ball cores A63B37/005

Abstract

A golf ball includes an inner core layer having a first surface hardness and a geometric center hardness. The center hardness is less than the first surface hardness to define a first positive hardness gradient of about 1 to 12 Shore C. An outer core layer has a second surface hardness. A cover layer is formed over the outer core layer. The second outer surface hardness is greater than the geometric center hardness to define a second positive hardness gradient of about 12 to 22 Shore C.

Claims

1. A golf ball comprising:

an inner core layer having a first surface hardness and a geometric center hardness, the center hardness being less than the first surface hardness to define a first positive hardness gradient of about 1 to 12 Shore C;

an outer core layer having a second surface hardness; and

a cover layer disposed about the outer core layer;

wherein the second outer surface hardness is greater than the geometric center hardness to define a second positive hardness gradient of about 12 to 22 Shore C, and wherein the first hardness gradient has a first slope, S₁, and the second hardness gradient has a second slope, S₂, and a ratio of S₂ to S₁ is about 10.0 or greater.

2. The golf ball of claim 1, wherein the geometric center hardness is about 65 to 75 Shore C and the second surface hardness is greater than about 85 Shore C.

3. The golf ball of claim 1, wherein the first hardness gradient is about 3 to 10 Shore C.

4. The golf ball of claim 3, wherein the first hardness gradient is about 4 to 9 Shore C.

5. The golf ball of claim 1, wherein the first hardness gradient of about 1 to 5 Shore D.

6. The golf ball of claim 1, wherein the cover layer comprises a polyurea, a polyurethane, or a hybrid thereof.

7. The golf ball of claim 1, wherein the cover layer comprises an inner cover layer and an outer cover layer.

8. The golf ball of claim 7, wherein the inner cover layer comprises an ionomer and the outer cover layer comprises a polyurethane, the inner cover layer being harder than the outer cover layer.

9. The golf ball of claim 1, wherein the second positive hardness gradient is about 13 to 21 Shore C.

10. The golf ball of claim 9, wherein the second positive hardness gradient is about 14 to 20 Shore C.

11. The golf ball of claim 10, wherein the second positive hardness gradient is about 8 to 13 Shore D.

12. The golf ball of claim 1, wherein the ratio of S₂ to S₁ is from about 15.0 to about 20.0.

13. The golf ball of claim 1, wherein an angle between an intersection of linear regression fits of the first and second hardness gradients, θ

, is about 90°

or greater, wherein θ

is defined by the equation;

14. The golf ball of claim 13, wherein θ

is about 100°

or greater.

15. The golf ball of claim 14, wherein θ

is about 110°

or greater.

16. The golf ball of claim 15, wherein θ

is about 120°

or greater.

17. A golf ball comprising:

an inner core layer having a first surface hardness of about 75 to 79 Shore C and a geometric center hardness, the center hardness being about 69 to 73 Shore C and less than the first surface hardness to define a first positive hardness gradient of about 5 to 9 Shore C, the first positive hardness gradient having a first slope S₁;

an outer core layer having a second surface hardness of about 86 to 91 Shore C; and

a cover layer disposed about the outer core layer;

wherein the second outer surface hardness is greater than the geometric center hardness to define a second positive hardness gradient of about 16 to 19 Shore C, the second positive hardness gradient having a second slope S₂ such that a ratio of S₂ to S₁ is about 10.0 or greater; and

wherein the inner core layer comprises an antioxidant and the outer core layer is substantially free from antioxidant.