GOLF BALL

• US 20130324318A1
• Filed: 05/31/2013
• Published: 12/05/2013
• Est. Priority Date: 06/01/2012
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Dunlop Sports Co. Ltd. (Sumitomo Rubber Industries Limited)
• Inventors: ISOGAWA, Kazuhiko, TACHIBANA, Kosuke, SAJIMA, Takahiro, TARAO, Toshiyuki
• Granted Patent: US 9,248,347 B2
• Time in Patent Office: Days
• US Class Current: 473/373
• CPC Class Codes: A63B 37/0003 Golf balls
• CPC Class Codes: A63B 37/0004 Surface depressions or protrusions
• CPC Class Codes: A63B 37/0006 Arrangement or layout of dimples
• CPC Class Codes: A63B 37/0018 Specified number of dimples
• CPC Class Codes: A63B 37/0021 Occupation ratio, i.e. percentage surface occupied by dimples
• CPC Class Codes: A63B 37/0033 Thickness
• CPC Class Codes: A63B 37/0038 Intermediate layers, e.g. inner cover, outer core, mantle
• CPC Class Codes: A63B 37/0039 characterised by the material
• CPC Class Codes: A63B 37/0044 Hardness gradient
• CPC Class Codes: A63B 37/0045 Thickness
• 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 37/0075 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 37/00776 Slab hardness
• CPC Class Codes: A63B 37/00922 whereby hardness of the cover is lower than hardness of the intermediate layers
• CPC Class Codes: C08K 5/09 Carboxylic acids; Metal salts thereof; Anhydrides thereof
• CPC Class Codes: C08K 5/098 Metal salts of carboxylic acids
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

The present invention provides a golf ball comprising a golf ball body with a spherical core having one or more layers, an intermediate layer disposed outside the spherical core and a cover disposed outside the intermediate layer and a paint film formed on a surface of the golf ball body, and having a friction coefficient calculated using a contact force tester of 0.35 or more and 0.60 or less, wherein the golf ball body has specific plurality of dimples on the surface thereof, at least one layer of the spherical core is a rubber layer having a specific hardness distribution, and the rubber layer has a hardness at the outermost point which is greater than a hardness at the innermost point, and the intermediate layer has a slab hardness (Hm) which is greater than a slab hardness (Hc) of the cover.

Claims

1. A golf ball comprising

a golf ball body having

a spherical core composed of at least one layer,

an intermediate layer disposed outside the spherical core,

a cover disposed outside the intermediate layer, and

a paint film formed on a surface of the golf ball body, wherein

the golf ball has a coefficient of friction calculated using a contact force tester of 0.35 or more and 0.60 or less;

the golf ball has a plurality of dimples on a surface thereof, the dimples satisfying a following mathematical formula (I);

Y≦

3.8*X−

2.894 

 

(I)

(In the mathematical formula (I), X represents a ratio of a total area of all the dimples to a surface area of a phantom sphere of the golf ball, and Y represents a standard deviation (mm) of diameters of all the dimples),

at least one layer of the spherical core is a rubber layer formed from a rubber composition, the rubber layer is such that R² of a linear approximation curve obtained from a least square method is 0.95 or higher, when JIS-C hardness, which is measured at nine points obtained by dividing a thickness of the rubber layer into equal parts having 12.5% intervals in a radius direction of the spherical core, is plotted against distance (%) from an innermost point of the rubber layer; and

the rubber layer has a hardness at an outermost point which is greater than a hardness at the innermost point; and

the intermediate layer has a slab hardness (Hm) which is greater than a slab hardness (Hc) of the cover.

2. The golf ball according to claim 1, wherein the spherical core has a center hardness (Ho) ranging from 40 to 70 in JIS-C hardness and a surface hardness (Hs) ranging from 76 to 96 in JIS-C hardness.

3. The golf ball according to claim 1, wherein the spherical core has a hardness difference of 15 or more in JIS-C hardness between a surface hardness (Hs) thereof and a center hardness (Ho) thereof.

4. The golf ball according to claim 1, wherein a hardness difference between a slab hardness (Hm) of the intermediate layer and a slab hardness (Hc) of the cover is 30 or more in JIS-C hardness.

5. The golf ball according to claim 1, wherein the intermediate layer has a thickness ranging from 0.5 mm to 1.6 mm, and the cover has a thickness of 0.8 mm or less.

6. The golf ball according to claim 1, wherein the rubber layer is formed from a rubber composition containing (a) a base rubber, (b1) an α

,β

-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or (b2) a metal salt of the α

,β

-unsaturated carboxylic acid having 3 to 8 carbon atoms as (b) a co-crosslinking agent, (c) a crosslinking initiator, and (d) an acid and/or a salt thereof.

7. The golf ball according to claim 6, wherein (d) the acid and/or the salt thereof is a carboxylic acid and/or a salt thereof.

10. The golf ball according to claim 6, wherein the rubber composition contains (d) the acid and/or the salt thereof in an amount of 1 part by mass or more and less than 40 parts by mass with respect to 100 parts by mass of (a) the base rubber.

11. The golf ball according to claim 1, wherein a base resin constituting the paint film is a polyurethane obtained by a reaction between a polyol and two or more polyisocyanates.

12. The golf ball according to claim 11, wherein the two or more polyisocyanates include a derivative of hexamethylene diisocyanate and a derivative of isophorone diisocyanate.

13. The golf ball according to claim 12, wherein the derivative of hexamethylene diisocyanate includes a biuret-modified product of hexamethylene diisocyanate and isocyanurate of hexamethylene diisocyanate.

14. The golf ball according to claim 12, wherein the derivative of isophorone diisocyanate includes isocyanurate of isophorone diisocyanate.

15. The golf ball according to claim 11, wherein a molar ratio (NCO/OH) of the isocyanate group (NCO) of the two or more polyisocyanates to the hydroxyl group (OH) of the polyol is 0.1 or more and 1.0 or less in the reaction between the two or more polyisocyanates and the polyol.

16. The golf ball according to claim 1, wherein the ratio X is 0.78 or more.

17. The golf ball according to claim 1, wherein the standard deviation Y (mm) of diameters of all the dimples is 0.30 mm or less.

18. The golf ball according to claim 1, wherein a total number of dimples is 300 or more and 400 or less.

19. The golf ball according to claim 1, wherein each of the dimples has a contour in a circle shape.

20. The golf ball according to claim 1, further satisfying a following mathematical formula (II).

Y≦

3.8*X−

2.944 

 

(II)

21. The golf ball according to claim 1, further satisfying a following mathematical formula (III).

Y≦

3.8*X−

2.994 

 

(III)

8. The golf ball according to claim 8, wherein (d) the carboxylic acid and/or the salt thereof is a fatty acid and/or a salt thereof.

9. The golf ball according to claim 8, wherein (d) carboxylic acid and/or the salt thereof has a fatty acid component having 1 to 30 carbon atoms.