Golf ball

• US 7,029,406 B2
• Filed: 03/25/2004
• Issued: 04/18/2006
• Est. Priority Date: 03/28/2003
• Status: Expired due to Fees

• Current Assignee: Bridgestone Sports Co Limited (Bridgestone Corporation)
• Original Assignee: Bridgestone Sports Co Limited (Bridgestone Corporation)
• Inventors: Ichikawa, Yasushi, Kasashima, Atsuki
• Primary Examiner(s): TRIMIEW, RAEANN
• Application Number:
  US10/808,452
• Publication Number:
  US 20040192473A1
• Time in Patent Office: 754 Days
• Field of Search: 473/376, 473378-385
• US Class Current: 473/378
• CPC Class Codes: A63B 37/0003 Golf balls
• CPC Class Codes: A63B 37/0017 Specified total dimple volume
• CPC Class Codes: A63B 37/0033 Thickness
• CPC Class Codes: A63B 37/0075 Three piece balls, i.e. cover, intermediate layer and core
• CPC Class Codes: A63B 37/0082 Density; Specific gravity
• CPC Class Codes: A63B 37/0096 Spin rate

Abstract

In a golf ball comprising an elastic core, an intermediate layer of at least one layer, and a cover which is provided on its surface with a plurality of dimples, wherein the cover has a gage of 1.0–1.5 mm, the intermediate layer has a gage of 1.0–2.0 mm per layer, the golf ball in its entirety has a specific gravity of 1.128–1.145 g/cm³. On account of an optimum specific gravity in a relatively high range, the ball is improved in flight performance.

Claims

1. A golf ball comprising an elastic core, an intermediate layer of at least one layer formed of at least one ionomer resin enclosing the elastic core, and a cover which is formed of at least one thermoplastic or thermosetting urethane resin and provided on its surface with a plurality of dimples, wherein

the cover has a gage of 1.0 to 1.5 mm, and a Shore D hardness of 45 to 63,

the intermediate layer has a gage of 1.0 to 2.0 mm per layer and a Shore D hardness of 50 to 70, and which is harder than the hardness of the cover,

wherein a phantom sphere is given on the assumption that the cover surface is free of dimples, the total of the volumes of dimple spaces each delimited by a concave wall of a dimple and the surface of the phantom sphere is 1.1 to 1.6% of the volume of the phantom sphere, and

the golf ball in its entirety has a specific gravity of at least 1.128 g/cm³.

2. The golf ball of claim 1 wherein the specific gravity of the golf ball is up to 1.145 g/cm³.

3. The golf ball of claim 1 wherein a phantom sphere is given on the assumption that the cover surface is free of dimples, the total of the volumes of dimple spaces each delimited by a concave wall of a dimple and the surface of the phantom sphere is 1.1 to 1.6% of the volume of the phantom sphere.

4. The golf ball of claim 1 wherein the golf ball in flight has a coefficient of lift CL and a coefficient of drag CD, and the ratio CL/CD is 0.676 to 0.796 under a set of conditions:

Reynolds number 200,000 and spin rate 2,700 rpm, 0.813 to 0.933 under a set of conditions;

Reynolds number 120,000 and spin rate 2,400 rpm, and 0.856 to 0.976 under a set of conditions;

Reynolds number 80,000 and spin rate 2,000 rpm.

5. The golf ball of claim 1 wherein the cover is formed by injection molding.

6. The golf ball of claim 1, wherein the specific gravity of the golf ball is in the range of 1.135 g/cm³ to 1.145 g/cm³.

7. The golf ball of claim 1, wherein an amount of deformation (in mm) under a load, of the elastic core incurred when the load is increased from an initial value of 98 N (10 kgf) to a final value of 1274 N (130 kgf), is in the range of 2 mm to 4.5 mm.

8. The golf ball of claim 1, wherein the intermediate layer is composed of an inner layer formed of polyester elastomer and an outer layer formed of at least one ionomer resin.