Solid golf ball

Details Solid golf ball Solid golf ball

2001-12-20

2004-06-08

Gordon, Raeann (Department: 3711)

Games using tangible projectile

Golf

Ball

Reexamination Certificate

active

06746347

ABSTRACT:

This invention relates to a solid golf ball comprising an elastic solid core and a resin cover of at least one layer enclosing the solid core, and more particularly, to a solid golf ball which prevents substantial reduction of spin when hit in the wet state with a short iron. As used herein, the term “wet state” refers to the state of a golf course in rain weather, and the term “dry state” refers to the state of a golf course in fine weather.
BACKGROUND OF THE INVENTION
One of known solid golf balls has the structure in which a rubbery elastic solid core is enclosed with a cover of relatively hard ionomer resin characterized by good external damage prevention such as cut resistance and abrasion resistance.
The golf ball of this structure performs well in the dry state or fine weather in that it travels a satisfactory distance when hit with a driver and receives a requisite spin when hit with an iron which demands controllability to the ball. In the wet state or rain weather, however, the ball becomes less susceptible to spin and therefore, becomes less controllable when hit with an iron club. In particular, the spin susceptibility of the ball when hit with a short iron having a loft of an 8-iron or greater is degraded. As a result, the ball will travel a longer distance than intended or will not stop immediately on the green, about which professional and low-handicap golfers complain. It is desired to overcome the above problem.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to provide a solid golf ball comprising an elastic solid core and a resin cover of at least one layer, which ball is easy to control on short iron shots because, with respect to the spin the ball receives when hit with a short iron, the percent retention of the spin in the wet state from the spin in the dry state is high.
According to the invention, there is provided a solid golf ball comprising an elastic solid core and a resin cover of at least one layer enclosing the solid core. The cover has a JIS-C hardness of up to 85. The percent spin retention given by (S
2
/S
1
)×100 is at least 47%, provided that the ball receives a spin rate S
1
(rpm) in the dry state and a spin rate S
2
(rpm) in the wet state when hit with a short iron having a loft of an 8-iron or greater.
In one preferred embodiment, the cover is composed of a plurality of layers including inner and outer layers, the cover outer layer has a JIS-C hardness of up to 85, the cover inner layer has a JIS-C hardness of at least 55, and the JIS-C hardness of the cover outer layer is lower than that of the cover inner layer.
Preferably, the cover or the cover outer layer has a flexural rigidity of up to 196 MPa (2000 kgf/cm
2
). Also preferably, the cover or the cover outer layer has a flexural rigidity A (kgf/cm
2
) and a JIS-C hardness B, A and B satisfy the relationship:
A≧
300+0.37×
e
(0.098×B)
wherein e is the base of natural logarithm.
In the preferred embodiment wherein the cover is composed of a plurality of layers including inner and outer layers, an adhesive layer intervenes between the cover inner and outer layers.
The invention ensures that the spin susceptibility of the ball when hit with a short iron having a loft of an 8-iron or greater is not reduced in the dry state or fine weather, nor is noticeably reduced even in the wet state or rain weather. Then the ball travels a distance as intended, immediately stops on the green, and is easy to control. This is a high-performance solid golf ball suited for professional and amateur low-handicap golfers to play with.


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