Golf balls having a core layer made from plasticized thermoplastic compositions

• US 9,526,948 B2
• Filed: 08/15/2014
• Issued: 12/27/2016
• Est. Priority Date: 01/10/2008
• Status: Active Grant

• Current Assignee: Acushnet Company (FILA Holdings Corp.)
• Original Assignee: Acushnet Company (FILA Holdings Corp.)
• Inventors: Sullivan, Michael J., Binette, Mark L., Blink, Robert, Bulpett, David A., Comeau, Brian
• Primary Examiner(s): Gorden, Raeann
• Application Number:
  US14/460,416
• Publication Number:
  US 20150031475A1
• Time in Patent Office: 865 Days
• Field of Search: 473/371
• US Class Current: 1/1
• CPC Class Codes: A63B 37/0003 Golf balls
• CPC Class Codes: A63B 37/0031 Hardness
• CPC Class Codes: A63B 37/0033 Thickness
• 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 37/0045 Thickness
• CPC Class Codes: A63B 37/0046 Deflection or compression
• CPC Class Codes: A63B 37/0051 Materials other than polybutadienes; Constructional details
• CPC Class Codes: A63B 37/0059 Ionomer
• 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 37/0068 Initial velocity
• CPC Class Codes: A63B 37/0074 Two piece balls, i.e. cover and core
• 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 37/0087 Deflection or compression
• CPC Class Codes: A63B 37/0092 Hardness distribution amongst different ball layers
• CPC Class Codes: A63B 37/0096 : Spin rate
• CPC Class Codes: A63B 37/02 : Special cores balls with finger holes A63B37/0001, golf ball cores A63B37/005

Abstract

Multi-layered golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a thermoplastic composition, preferably including: a) ethylene acid copolymer, b) plasticizer, and c) cation source. Preferably, a fatty acid ester such as ethyl oleate is used as the plasticizer. The outer core layer is preferably formed from a thermoset composition such as polybutadiene rubber. The core layers have different hardness levels. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency at given compressions.

Claims

1. A core assembly for a golf ball, comprising:

i) an inner core layer comprising a thermoplastic composition, the inner core having an outer surface hardness (H_{inner core surface}) and a center hardness (H_{inner core center}), the H_{inner core surface} being greater than the H_{inner core center} to provide a positive hardness gradient, the thermoplastic composition comprising;

a) an acid copolymer of ethylene and an α

,β

-unsaturated carboxylic acid, optionally including a softening monomer selected from the group consisting of alkyl acrylates and methacrylates;

b) a plasticizer; and

c) a cation source present in an amount sufficient to neutralize from about 0 to about 100% of all acid groups present in the composition; and

ii) an outer core layer comprising a thermoset rubber composition, the outer core layer being disposed about the inner core layer and having an outer surface hardness (H_{outer surface of OC}) and a midpoint hardness (H_{midpoint of OC}), the H_{outer surface of OC} being greater than the H_{midpoint of OC} to provide a positive hardness gradient,

wherein the center hardness of the inner core (H_{inner core center}) is in the range of about 10 Shore C to about 70 Shore C and the outer surface hardness of the outer core layer (H_{outer surface of OC}) is in the range of about 20 Shore C to about 95 Shore C to provide a positive hardness gradient across the core assembly.

2. The core assembly of claim 1, wherein the thermoplastic composition further comprises a non-acid polymer selected from the group consisting of polyolefins, polyamides, polyesters, polyethers, polyurethanes, metallocene-catalyzed polymers, single-site catalyst polymerized polymers, ethylene propylene rubber, ethylene propylene diene rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers, and functionalized derivatives thereof.

3. The core assembly of claim 2, wherein the acid copolymer of ethylene and an α

,β

-unsaturated carboxylic acid does not include a softening monomer, and wherein the acid is selected from acrylic acid and methacrylic acid and is present in the acid copolymer in an amount of from about 15 to about 30 weight %, based on the total weight of the acid copolymer.

4. The core assembly of claim 2, wherein the non-acid polymer is an alkyl acrylate rubber selected from ethylene-alkyl acrylates and ethylene-alkyl methacrylates and is present in an amount of greater than 50 wt. %, based on the combined weight of the acid copolymer and the non-acid polymer.

5. The core assembly of claim 4, wherein the non-acid polymer is ethylene-n-butyl acrylate, wherein the n-butyl-acrylate is present in an amount of 20 wt. % or greater, based on the total weight of the non-acid polymer composition.

6. The core assembly of claim 1, wherein the thermoset rubber composition comprises polybutadiene.

7. The core assembly of claim 1, wherein the outer core has a thickness in the range of about 0.100 to about 0.750 inches.

8. The core assembly of claim 1, wherein the thermoplastic composition comprises about 3 to about 50% by weight plasticizer.

9. The core assembly of claim 1, wherein the thermoplastic composition comprises about 8 to about 42% by weight plasticizer.

10. The core assembly of claim 1, wherein the thermoplastic composition comprises about 10 to about 30% by weight plasticizer.

11. The core assembly of claim 1, wherein the plasticizer is a fatty acid ester.

12. The core assembly of claim 1, wherein the plasticizer is an alkyl oleate.

13. The core assembly of claim 12, wherein the plasticizer is ethyl oleate.

14. The core assembly of claim 1, wherein the thermoplastic material comprises an ethylene add copolymer containing add groups such that 70% or less of the acid groups are neutralized.

15. The core assembly of claim 14, wherein the thermoplastic material comprises an ethylene acid copolymer containing acid groups such that 20% or less of the acid groups are neutralized.

16. The core assembly of claim 1, wherein the thermoplastic material comprises an ethylene acid copolymercontaining add groups such that greater than 70% of the acid groups are neutralized.

17. The core assembly of claim 16, wherein 90% or greater of the acid groups are neutralized.

18. The core assembly of claim 1, wher in the acid groups are neutralized by a metal cation salt.

19. The core assembly of claim 18, wherein the metal cation is selected from the group consisting of Zn, Na, Li, K, Ca, Mg, Ni, Mn, Cu, Ti, and Al, and mixtures thereof.

20. The core assembly of claim 1, wherein the ethylene acid copolymer is selected from the group consisting of ethylene/(meth)acrylic acid/n-butyl acrylate;

ethylene/(meth)acrylic acid/ethyl acrylate;

ethylene/(meth)acrylic acid/methyl acrylate;

ethylene/(meth)acrylic acid/n-butyl acrylate; and

ethylene/(meth)acrylic acid/isobutyl acrylate copolymers.

21. The core assembly of claim 1, wherein the inner core layer has a diameter in the range of about 0.100 to about 1.100 inches.

22. The core assembly of claim 1, wherein the H_{inner core center} is in the range of about 10 Shore C to about 70 Shore C and the H_{inner core surface} is in the range of about 15 Shore C to about 90 Shore C.

23. The core assembly of claim 1, wherein the H_{midpoint of OC} is in the range of about 20 Shore C to about 85 Shore C and the H_{outer surface of OC} is in the range of about 30 Shore C to about 95 Shore C.

24. The core assembly of claim 1, wherein the center hardness of the inner core (H_{inner core center})is in the range of about 30 Shore C to about 65 Shore C and the outer surface hardness of the outer core layer (H_{outer surface of OC}) is in the range of about 40 Shore C to about 85 Shore C to provide a positive hardness gradient across the core assembly.