Golf ball

• US 7,300,363 B2
• Filed: 02/07/2005
• Issued: 11/27/2007
• Est. Priority Date: 02/07/2005
• Status: Active Grant

• Current Assignee: Bridgestone Sports Co Limited (Bridgestone Corporation)
• Original Assignee: Bridgestone Sports Co Limited (Bridgestone Corporation)
• Inventors: Kasashima, Atsuki
• Primary Examiner(s): GORDEN, RAEANN
• Application Number:
  US11/050,770
• Publication Number:
  US 20060178231A1
• Time in Patent Office: 1,023 Days
• Field of Search: 473/378, 473/373, 473/374, 473/368
• US Class Current: 473/376
• CPC Class Codes: A63B 37/0004 Surface depressions or protrusions
• CPC Class Codes: A63B 37/0012 Dimple profile, i.e. cross-sectional view
• CPC Class Codes: A63B 37/0017 Specified total dimple volume
• CPC Class Codes: A63B 37/0018 Specified number of dimples
• CPC Class Codes: A63B 37/002 Specified dimple diameter
• CPC Class Codes: A63B 37/0021 Occupation ratio, i.e. percentage surface occupied by dimples
• 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 37/0063 Hardness gradient
• 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 37/0089 Coefficient of drag
• CPC Class Codes: A63B 37/009 Coefficient of lift
• CPC Class Codes: A63B 37/0096 Spin rate

Abstract

A golf ball is composed of a resilient core, a cover which encloses the core, is made primarily of a polyurethane thermoplastic elastomer and has on a surface thereof 250 to 370 dimples, and at least one intermediate layer disposed between the core and the cover. The core has a center portion and a surface portion that is harder than the center portion, the hardness difference expressed in JIS-C hardness units being in a range of 15 to 30, and has a deflection of 1.8 to 4.0 mm when subjected to an increase in load from an initial load state of 98 N (10 kgf) to a load of 1,275 N (130 kgf). The intermediate layer has a Shore D hardness of 55 to 75, and the cover has a Shore D hardness of 30 to 58. The dimples, which are a combination of at least five types having contour lengths at a dimple edge position in a range of 7 to 20 mm, have a total volume of 400 to 700 mm³ and a surface coverage relative to an overall surface of the ball of at least 79%.

Claims

1. A golf ball comprising a resilient core, a cover which encloses the core, is made primarily of polyurethane resin and has on a surface thereof 250 to 370 dimples, and at least one intermediate layer disposed between the core and the cover, the golf ball being characterized in that the core is formed with a center portion and a surface portion that is harder than the center portion, the hardness difference expressed in JIS-C hardness units being in a range of 15 to 30, and has a deflection of 1.8 to 4.0 mm when subjected to an increase in load from an initial load state of 98 N (10 kgf) to a load of 1,275 N (130 kgf), the intermediate layer has a Shore D hardness of 55 to 75, the cover has a Shore D hardness of 30 to 58, and the dimples are a combination of at least five types having contour lengths at a dimple edge position in a range of 7 to 20 mm, which dimples have a total volume of 400 to 700 mm³ and a surface coverage relative to an overall surface of the ball of at least 79% which, when hit, has a coefficient of lift CL at a Reynolds number of 70,000 and a spin rate of 2,000 rpm that is at least 70% of the coefficient of lift CL at a Reynolds number of 80,000 and a spin rate of 2,000 rpm, and has a coefficient of drag CD at a Reynolds number of 180,000 and a spin rate of 2,520 rpm of not more than 0.225.

2. The golf ball of claim 1, wherein the core has a JIS-C hardness in the center portion of 57 to 67 and a JIS-C hardness in the surface portion of 80 to 90.

3. The golf ball of claim 1, wherein dimples having contour lengths at the dimple edge position in a range of 13 to 20 mm account for at least 70% of the total number of dimples.

4. The golf ball of claim 1, wherein the resilient core has a deflection when subjected to an increase in load from an initial load state of 98 N (10 kgf) to a load of 1,275 N (130 kgf) of 2.0 to 3.5 mm.

5. The golf ball of claim 1, wherein the intermediate layer is formed so as to have a Shore D hardness which is no more than 25 units higher than the Shore D hardness of the cover.

6. The golf ball of claim 1, wherein the core is designed so as to have a hardness that increases gradually from the center portion toward the surface portion thereof.

7. The golf ball of claim 1, wherein the cover has a thickness of 0.5 to 1.5 mm.

8. The multi-piece solid golf ball of claim 1, which is four piece solid golf ball.

9. A golf ball comprising a resilient core, a cover which encloses the core, is made primarily of polyurethane resin and has on a surface thereof 250 to 370 dimples, and at least one intermediate layer disposed between the core and the cover, the golf ball being characterized in that the core is formed with a center portion and a surface portion that is harder than the center portion, the hardness difference expressed in JIS-C hardness units being in a range of 15 to 30, and has a deflection of 1.8 to 4.0 mm when subjected to an increase in load from an initial load state of 98 N (10 kgf) to a load of 1,275 N (130 kgf), the intermediate layer has a Shore D hardness of 55 to 75, the cover has a Shore D hardness of 30 to 58, and the dimples are a combination of at least five types having contour lengths at a dimple edge position in a range of 7 to 20 mm, which dimples have a total volume of 400 to 700 mm³ and a surface coverage relative to an overall surface of the ball of at least 79%,

wherein the number of dimples is in a range of 250 to 330.

10. The golf ball of claim 9, wherein the core has a JIS-C hardness in the center portion of 57 to 67 and a JIS-C hardness in the surface portion of 80 to 90.

11. The golf ball of claim 9, wherein dimples having contour lengths at the dimple edge position in a range of 13 to 20 mm account for at least 70% of the total number of dimples.

12. The golf ball of claim 9, wherein the resilient core has a deflection when subjected to an increase in load from an initial load state of 98 N (10 kgf) to a load of 1,275 N (130 kgf) of2.0 to 3.5 mm.

13. The golf ball of claim 9, wherein the intermediate layer is formed so as to have a Shore D hardness which is no more than 25 units higher than the Shore D hardness of the cover.

14. The golf ball of claim 9, wherein the core is designed so as to have a hardness that increases gradually from the center portion toward the surface portion thereof.

15. The golf ball of claim 9, wherein the cover has a thickness of 0.5 to 1.5 mm.

16. The multi-piece solid golf ball of claim 9, which is four piece solid golf ball.