Multi-piece golf ball

Details Multi-piece golf ball Multi-piece golf ball

1999-10-19

2002-03-26

Graham, Mark S. (Department: 3711)

Games using tangible projectile

Golf

Ball

C473S374000

Reexamination Certificate

active

06361454

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-piece golf ball excellent in flight performance and shot feeling. More particularly it relates to a multi-piece golf ball having an improved shot feeling while retaining a low spin and high trajectory angle inherent in two-piece golf balls.
2. Description of the Prior Art
Hitherto, there have been used thread-wound golf balls and two-piece golf balls. The former is obtained by winding a rubber thread around a center filled with a solid or liquid and then covering the rubber-thread wound center with a cover mainly made of balata or synthetic resin. The latter is obtained by covering a rubber core with a cover made of a synthetic resin such as ionomer.
Thread-wound golf balls provides a good shot feeling because players receive small impact when hitting the ball and has a good controllability because players can impart intentional spin on the golf ball. However, since thread-wound golf balls are liable to spin, a sufficient flying distance cannot be secured in a wind ahead. In addition, they are poor in durability. As compared with thread-wound golf balls, two-piece golf balls have superior durability and can ensure a lower flying distance in a wind ahead because they are not susceptible to spin and have a relatively high coefficient of restitution. The high coefficient of restitution of the two-piece golf ball is resulting from the hard core, namely the core made from a hard material such as ionomor. However the hard core of the two-piece golf ball contributes to giving players a bigger impact than the thread-wound golf ball when hitting, which means inferior shot feeling to the thread-wound golf balls.
Japanese Patent Laid-Open Nos. 336617/1996, 336618/1996, 56848/1997, 248351/1997, 266959/1997 and 299510/1997 propose multi-piece golf balls which have improved shot feeling while ensuring a good flight performance of two-piece golf balls. The multi-piece golf balls have a multi-layered structure selected from the following groups: one has a core consisting of multi-layers; one has a cover consisting of multi-layers; and one has one or more intermediate layers placed between the cover and the core. And each layer constituting the multi-piece golf ball has an appropriate hardness to obtain both of a good flight performance and shot feeling.
The multi-piece golf balls as disclosed in the above publications are roughly classified into three groups: ones in which the outermost layer of a cover is the hardest and a relatively soft layer is placed on the inside of the cover (e.g., 336617/1996); ones in which a softer intermediate layer than the core encloses the core (e.g., 336618/1996); and ones in which an intermediate layer enclosing the core is the hardest of all layers constituting of the golf ball (e.g., 266959/1997, 248351/1997).
There are, however, demands on further improvements in shot feeling and flying distance. Because the shot feeling depends on clubs. For example, when a hard cover is employed in order to increase the coefficient of restitution, the resultant golf ball provides a poor shot feeling upon use of a putter, although it is possible to reduce impact when hitting golf ball by a driver or an iron, Accordingly, it is a primary object of the present invention to provide a golf ball which offers excellent shot feeling with any kind of club, while retaining a high coefficient of restitution inherent in solid golf balls.
SUMMARY OF THE INVENTION
According to the present invention, a multi-piece golf ball comprises an inner core which is positioned in a central part of the golf ball and has a JIS-C hardness of 75 or smaller; an outer core which encloses the inner core; an outer cover which is positioned in a surface part of the golf ball ; and an inner cover which is placed on the inside of the outer cover and has a JIS-C hardness of 80 or larger. A JIS-C hardness of the outer core is smaller than that of the other components, and a JIS-C hardness of the outer cover is larger than that of the other components.
A multi-piece golf ball of the present invention further comprises an intermediate layer between the outer core and the inner cover.


REFERENCES:
patent: 5688595 (1997-11-01), Yamagishi et al.
patent: 5733205 (1998-03-01), Higuchi et al.
patent: 5779562 (1998-07-01), Melvin et al.
patent: 6056650 (2000-05-01), Yamagishi et al.
patent: 6117026 (2000-09-01), Hayashi et al.
Patent Abstracts of Japan, 08 336617, Dec. 24, 1996, Yamagishi Hisashi et al.
Patent Abstracts of Japan, 08 336618, Dec. 24, 1996, Higuchi Hiroshi et al.
Patent Abstracts of Japan, 09 056848, Mar. 4, 1997, Higuchi Hiroshi et al.
Patent Abstracts of Japan, 09 248351, Sep. 22, 1997, Shimozaka Hirotaka et al.
Patent Abstracts of Japan, 09 266959, Oct. 14, 1997, Osumi Shunji et al.
Patent Abstracts of Japan, 09 299510, Nov. 25, 1997, Hayashi Junji et al.

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