Multi-layer core golf ball

• US 9,931,543 B2
• Filed: 12/07/2016
• Issued: 04/03/2018
• Est. Priority Date: 08/05/2013
• Status: Active Grant

• Current Assignee: Acushnet Company (FILA Holdings Corp.)
• Original Assignee: Acushnet Company (FILA Holdings Corp.)
• Inventors: Sullivan, Michael J., Comeau, Brian, Goguen, Douglas S.
• Primary Examiner(s): Gorden, Raeann
• Application Number:
  US15/371,535
• Publication Number:
  US 20170080295A1
• Time in Patent Office: 482 Days
• Field of Search: 473373, 473374
• CPC Class Codes: A63B 37/0043 Hardness
• CPC Class Codes: A63B 37/0044 Hardness gradient
• CPC Class Codes: A63B 37/0045 Thickness
• CPC Class Codes: A63B 37/0051 Materials other than polybutadienes; Constructional details
• CPC Class Codes: A63B 37/00621 Centre hardness
• CPC Class Codes: A63B 37/00622 Surface hardness
• CPC Class Codes: A63B 37/0064 Diameter
• CPC Class Codes: A63B 37/0065 Deflection or compression
• 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

Abstract

Golf balls having a very high positive gradient multilayer core are provided. The multilayer core includes an outer core layer and a very soft, low compression inner core layer. The inner core layer is formed from an unfoamed composition and has a center hardness that is at least 40 Shore C points less than the outer surface hardness of the outer core layer.

Claims

1. A golf ball comprising a core and a cover, wherein the core consists essentially of:

a solid inner core layer formed from an unfoamed composition and having a diameter of 1.10 inches or less, a center Shore C hardness (H_center) of 15 or less, and an interface Shore C hardness (H_{inner core interface}) of from 5 to 35; and

an outer core layer having a thickness of 0.20 inches or greater, an inner surface Shore C hardness (H_{outer core inner surface}) of from 40 to 75, and an outer surface Shore C hardness (H_{outer surface}) of 80 or greater;

wherein H_{outer surface}−

H_center≥

70; and

wherein the inner core layer has a hardness gradient slope (S_{inner core}) defined as

2. The golf ball of claim 1, wherein ½

S_{outer core}>

S_{inner core}.

3. The golf ball of claim 1, wherein ⅖

S_{outer core}>

S_{inner core}.

4. The golf ball of claim 1, wherein ⅓

S_{outer core}>

S_{inner core}.

5. The golf ball of claim 1, wherein the interface Shore C hardness of the inner core layer (H_{inner core interface}) is from 5 to 30;

and wherein the inner core layer has a positive hardness gradient wherein 1<

H_{inner core interface}−

H_center<

15.

6. The golf ball of claim 1, wherein the interface Shore C hardness of the inner core layer (H_{inner core interface}) is from 5 to 15;

and wherein the inner core layer has a negative hardness gradient wherein the interface Shore C hardness of the inner core layer is less than the center Shore C hardness, or a zero hardness gradient.

7. The golf ball of claim 1, wherein the outer surface Shore C hardness of the outer core layer (H_{outer surface}) is 85 or greater.

8. A golf ball comprising a core and a cover, wherein the core consists essentially of:

a solid inner core layer formed from an unfoamed composition and having a diameter of 1.30 inches or less, a center Shore C hardness (H_center) of 40 or less, and an interface Shore C hardness (H_{inner core interface}) of from 5 to 50; and

an outer core layer having a thickness of 0.10 inches or greater, an inner surface Shore C hardness (H_{outer core inner surface}) of from 40 to 75, and an outer surface Shore C hardness (H_{outer surface}) of 80 or greater;

wherein H_{outer surface}−

H_center≥

40; and

wherein the inner core layer has a hardness gradient slope (S_{inner core}) defined as

9. The golf ball of claim 8, wherein ½

S_{outer core}>

S_{inner core}.

10. The golf ball of claim 8, wherein ⅖

S_{outer core}>

S_{inner core}.

11. The golf ball of claim 8, wherein ⅓

S_{outer core}>

S_{inner core}.

12. The golf ball of claim 8, wherein H_{outer surface}−

H_center≥

60.

13. The golf ball of claim 8, wherein the inner core layer has an overall positive hardness gradient wherein 1<

H_{inner core interface}−

H_center<

25.

14. The golf ball of claim 8, wherein the interface Shore C hardness of the inner core layer (H_{inner core interface}) is from 5 to 40;

and wherein the inner core layer has a negative hardness gradient wherein the interface Shore C hardness of the inner core layer is less than the center Shore C hardness, or a zero hardness gradient.

15. A golf ball comprising a core and a cover, wherein the core consists essentially of:

a solid inner core layer formed from an unfoamed composition and having a diameter of 1.10 inches or less, a center Shore C hardness (H_center) of 40 or less, and an interface Shore C hardness (H_{inner core interface}) of from 5 to 50; and

an outer core layer having a thickness of 0.20 inches or greater, an inner surface Shore C hardness (H_{outer core inner surface}) of from 40 to 75, and an outer surface Shore C hardness (H_{outer surface}) of 80 or greater;

wherein H_{outer surface}−

H_center≥

40; and

wherein the inner core layer has a hardness gradient slope (S_{inner core}) defined as

16. The golf ball of claim 15, wherein ½

S_{outer core}>

S_{inner core}.

17. The golf ball of claim 15, wherein ⅖

S_{outer core}>

S_{inner core}.

18. The golf ball of claim 15, wherein H_{outer surface}−

H_center≥

60.

19. The golf ball of claim 15, wherein the inner core layer has an overall positive hardness gradient wherein 1<

H_{inner core interface}−

H_center<

15.

20. The golf ball of claim 15, wherein the interface Shore C hardness of the inner core layer (H_{inner core interface}) is from 5 to 40;

and wherein the inner core layer has a negative hardness gradient wherein the interface Shore C hardness of the inner core layer is less than the center Shore C hardness, or a zero hardness gradient.