Games using tangible projectile – Golf – Ball
Reexamination Certificate
1999-12-06
2001-06-05
Graham, Mark S. (Department: 3711)
Games using tangible projectile
Golf
Ball
C473S351000, C473S378000, C522S038000
Reexamination Certificate
active
06241626
ABSTRACT:
This application is a continuation-in-part of U.S. application Ser. No. 08/495,062 filed Jun. 26, 1 995now U.S. Pat. No. 5,830,087.
1. Field of the Invention
The invention generally relates to golf balls, and more particularly to golf balls having cores and/or covers made of plastomers.
2. Background of the Invention
Golf balls comprise, in general, three types. The first type is a wound ball wherein a vulcanized rubber thread is wound under tension around a solid or semi-solid core, and thereafter enclosed in a single or multi-layer covering of tough, protective material. A second type of golf ball is a one-piece ball formed from a solid mass of moldable resilient material which has been cured to develop the necessary degree of hardness to provide utility. One-piece molded balls do not have an enclosing cover. A third type of ball is a multi-piece (two or more piece) non-wound ball which includes a solid or liquid core of one or more layers and a cover having one or more layers formed over the core.
While for many years the wound ball satisfied the standards of both the U.S.G.A. and most golfers, it has several disadvantages. For example, a wound ball is difficult to manufacture due to the number of production steps required and the careful control which must be exercised in each stage of manufacture to achieve suitable roundness, velocity or rebound, “click”, “feel” and the like. “Click” is the term applied to the sound produced by the ball when dropped on a hard surface or when struck with a golf club. “Feel” refers to how impact of the ball is transmitted through the club to the hands of the golfer. In addition, the balata cover material for the wound ball is susceptible to cutting when struck by a golf club.
The one-piece ball and the core for a multi-piece non-wound ball frequently are formed from a combination of materials such as polybutadiene, zinc diacrylate or zinc dimethacrylate, fillers and curing agent s which are molded under high pressure and temperature to provide a ball of suitable hardness and resiliene. One-piece balls are described, for example, in U.S. Pat. No. 3,313,545, U.S. Pat. No . 3,373,123 and U.S. Pat. No. 3,384,612. Multi-piece non-wound golf balls typically have a cover which contains a substantial quantity of ionomer. Useful ionomers include those sold by E.I. DuPont de Nemours Company under the name Surlyn as well as those sold by Exxon under the name lotek™. The use of ionomers in golf ball covers imparts toughness and cut resistance to the covers. It would be useful to develop golf ball covers which contain substantial quantities of non-ionomeric materials and which have the durability and other playability properties of ionomeric golf ball covers. Furthermore, it would be useful to develop durable one-piece golf balls having reduced quantities of polybutadiene.
SUMMARY OF THE INVENTION
An object of the invention is to provide a golf ball containing reduced quantities of ionomer.
Yet another object of the invention is to provide a golf ball containing reduced quantities of polybutadiene.
A further object of the invention is to provide a golf ball having playability characteristics similar to those of golf balls with ionomeric covers while containing reduced quantities of ionomer.
Yet another object of the invention is to provide a golf ball having a cover containing a non-ionomeric resin which is comparable in durability to a cover made from ionomeric resin.
Yet another object of the invention is to provide a non-ionomeric golf ball.
Another object of the invention is to provide a golf ball which does not contain polybutadiene.
A further object of the invention is to provide a high quality restricted flight golf ball.
Another object of the invention is to provide a method of making a golf ball using non-ionomeric materials.
A further object of the invention is to provide a method of making a golf ball product having reduced quantities of ionomer.
A further object of the invention is to provide a method of making a golf ball product having reduced quantities of polybutadiene.
Other objects will be in part obvious and in part pointed out more in detail hereafter.
In accordance with the invention, novel golf balls of excellent durability, click and feel are provided. In a preferred form, the invention is a golf ball comprising plastomer with a molecular weight distribution of about 1.5-4 and a composition distribution breadth index of greater than 30%, the golf ball having a coefficient of restitution of at least 0.600. One particularly preferred form of the invention is a golf ball having a core which comprises a plastomer. The plastomer can be cured (crosslinked) or uncured (uncrosslinked). Another particularly preferred form of the invention is a wound or non-wound golf ball having a cover comprising a plastomer. If plastomer is present at the outer surface of the ball, it is cured. Yet another particularly preferred form of the invention is a one-piece golf ball comprising a plastomer. The plastomer in at least the outer surface of the one-piece ball is cured. Furthermore, the plastomer throughout the thickness of the ball can be cured.
The plastomer used to form the golf ball preferably is a copolymer formed from ethylene. More preferably the plastomer is a copolymer of ethylene and at least one of butene, hexene and octene.
By crosslinking plastomer at the outer surface of the ball, the ball is provided with good cut resistance, thereby meeting the playability standards of commercial golf balls. While any peroxide curing agent having an activation temperature higher than the melting point of the plastomer can be used if the plastomer is to be cured, e.g. a one hour half life at 112° C. or higher, a preferred curing agent is 4,4 bis(tert-butylperoxy) butylvalerate having about 40% peroxide content.
The curing or crosslinking agent is employed in an amount appropriate to impart to the golf ball a crosslink density which is sufficient to provide the desired cut resistance, scuff resistance and surface hardness to the outside of the ball. In a one-piece ball, the amount of peroxide is sufficient to provide a usable compression, i.e. 60-110 PGA compression in addition to appropriate cut resistance, scuff resistance and hardness. A plastomer core or an inner cover layer of a multi-layer ball may not require crosslinking or curing.
Another preferred form of the invention is a method of making a golf ball product comprising forming a mixture comprising a plastomer with a molecular weight distribution of about 1.5-4 and a composition distribution breadth index of at least 30%, the quantity of plastomer being appropriate to form a golf ball product having a coefficient of restitution of at least 0.600, and molding the mixture to form a golf ball product. The golf ball product is a golf ball core, a one-piece golf ball, or a multi-piece golf ball with plastomer in at least one of the core and cover. Preferably, the mixture includes a curing agent for curing the plastomer.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. It should, however, be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.
REFERENCES:
patent: 5830087 (1998-11-01), Sullivan et al.
patent: 5971870 (1999-10-01), Sullivan et al.
patent: 6018003 (2000-01-01), Sullivan et al.
Binette Mark
Nesbitt R. Dennis
Sullivan Michael J.
Gorden Raeann
Graham Mark S.
Spalding Sports Worldwide Inc.
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