Game balls with cover containing post crosslinkable thermoplastic polyurethane and method of making same

• US 6,787,582 B2
• Filed: 04/09/2002
• Issued: 09/07/2004
• Est. Priority Date: 12/23/1999
• Status: Expired due to Term

• Current Assignee: Callaway Golf Company (Topgolf Callaway Brands Corp.)
• Original Assignee: Callaway Golf Company (Topgolf Callaway Brands Corp.)
• Inventors: Nesbitt, R. Dennis
• Primary Examiner(s): Buttner, David J.
• Application Number:
  US10/119,398
• Publication Number:
  US 20020156147A1
• Time in Patent Office: 882 Days
• Field of Search: 522/135, 522/142, 525/454, 525/455, 473/378, 473/600
• US Class Current: 522/135
• CPC Class Codes: A63B 37/0003 Golf balls
• CPC Class Codes: A63B 37/0024 Materials other than ionomers or polyurethane
• CPC Class Codes: A63B 37/0031 Hardness
• CPC Class Codes: A63B 37/0033 Thickness
• CPC Class Codes: A63B 37/0043 Hardness
• CPC Class Codes: A63B 37/0052 Liquid cores
• CPC Class Codes: A63B 37/0053 Thread wound
• CPC Class Codes: A63B 37/0061 Coefficient of restitution
• CPC Class Codes: A63B 37/0064 Diameter
• CPC Class Codes: A63B 37/0065 Deflection or compression
• CPC Class Codes: A63B 37/0067 Weight; Mass
• 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 37/12 Special coverings , i.e. outer layer material balls with finger holes A63B37/0001, golf ball covers A63B37/0023
• CPC Class Codes: A63B 45/00 Apparatus or methods for manufacturing balls working of plastics or substances in a plastic state B29

Abstract

A game ball having a cover formed from a crosslinkable thermoplastic polyurethane is disclosed. Various types of game balls are described, including golf balls and softballs. By selective exposure to radiation, the thermoplastic polyurethane cover is crosslinked and its hardness is increased. Typically, increases in hardness values of at least 2 units on the Shore D scale are realized upon exposure to 3.5 Mrads of gamma radiation.

Claims

1. A golf ball, comprising:

a central portion, and

a first cover layer formed over said central portion, said first cover layer comprising a crosslinkable thermoplastic polyurethane and an unsaturated co-agent capable of crosslinking said crosslinkable thermoplastic polyurethane, wherein said crosslinkable thermoplastic polyurethane is a post crosslinkable thermoplastic polyurethane.

2. The golf ball of claim 1, wherein said crosslinkable thermoplastic polyurethane is crosslinked via free radical initiation.

4. The golf ball of claim 2, wherein said free radical initiation can be effected by peroxide decomposition.

5. The golf ball of claim 1, wherein said unsaturated co-agent is a hydroxyl terminated polybutadiene.

6. The golf ball of claim 1, wherein said crosslinkable thermoplastic polyurethane has been substantially crosslinked.

7. The golf ball of claim 6, wherein said crosslinkable thermoplastic polyurethane has a Shore D hardness of from about 35 to about 72 before crosslinking and would experience an increase in Shore D hardness of at least 2 units if exposed to gamma radiation at a dosage of 3.5 Mrads.

8. The golf ball of claim 1, further comprising a second cover layer between said central portion and said first cover layer.

9. The golf ball of claim 1, wherein the otter surface of said cover layer comprising the crosslinkable polyurethane has been radiation-crosslinked.

3. The golf ball of clam 2, wherein said free radical initiation can be effected by exposure of said first cover layer to electromagnetic radiation.

10. A golf ball comprising:

a core; and

a multi-layer cover comprising at least an inner cover layer and an outer cover layer disposed about said core, at least one of said inner and outer cover comprising a thermoplastic polyurethane and an unsaturated co-agent capable of undergoing crosslinking upon exposure to about 3.5 Mrads of radiation, and thereby increasing in hardness by at least 2 units on the Shore D hardness scale.

11. The golf ball of claim 10, wherein said unsaturated co-agent is a hydroxyl terminated polybutadiene.

12. The golf ball of claim 10, wherein the outer cover layer comprises the crosslinkable thermoplastic polyurethane.

13. The golf ball of claim 10, wherein the inner cover layer comprises ionomer.

14. A method at forming a golf ball, comprising:

providing a golf ball center, and

forming a cover over said golf ball center, said cover comprising a crosslinkable thermoplastic polyurethane and an unsaturated co-agent capable of crosslinking said crosslinkable thermoplastic polyurethane, thereby forming said golf ball.

15. The method of claim 14, wherein said crosslinkable thermoplastic polyurethane is crosslinked via free radical initiation.

16. The method of claim 15, wherein said free radical initiation can be effected by exposure of said first cover layer to electromagnetic radiation.

17. The method of claim 15, wherein said free radical initiation can be effected by peroxide decomposition.

18. The method of claim 14, wherein said cover comprises a multi-layer cover.