Games using tangible projectile – Golf – Ball
Reexamination Certificate
1999-12-03
2004-11-02
Gorden, Raeann (Department: 3711)
Games using tangible projectile
Golf
Ball
Reexamination Certificate
active
06811497
ABSTRACT:
FIELD OF INVENTION
This invention relates to two-piece, three-piece and multi-component fluid center golf balls comprising one or more layers formed with compositions that provide increased resistance to water permeation while still exhibiting good ball properties. These compositions may be incorporated into the cover and/or the core of a two-piece ball, or within the cover, core, center, and/or intermediate layer of a three-piece or multi-component golf ball.
BACKGROUND OF THE INVENTION
Conventional golf balls can be divided into several general types or groups: (1) one-piece balls; (2) two-piece balls; (3) wound balls; and (4) other balls with three or more layers. The difference in play characteristics resulting from these different constructions can be quite significant.
Balls having a two-piece construction are generally most popular with the average recreational golfer because they provide maximum distance. Two-piece balls commonly include a single solid core, usually formed of a crosslinked rubber. Solid cores are often formed of polybutadiene that is chemically crosslinked with zinc diacrylate and/or similar crosslinking agents. They are covered by a tough, cut-resistant blended cover, formed of a material such as SURLYN®, an ionomer resin produced by E. I. Du Pont de Nemours & Co. of Wilmington, Del. The combination of the core and cover materials imparts a relatively high initial velocity to the ball which results in improved distance. Due to the relative rigidity of these materials, two-piece balls have a hard “feel” when struck with a club.
At the present time, the wound ball remains the preferred ball of the more advanced players due to its spin and feel characteristics. Wound balls typically have either a solid rubber or fluid-filled center around which many yards of a stretched elastic thread or yarn are wound to form a core. The wound core is then covered with a durable cover material such as SURLYN®, or a softer material, such as balata or a castable polyurethane. Wound balls are generally softer and provide more spin than the aforementioned two-piece balls. Particularly with approach shots onto the green, the high spin rate of a soft, wound ball enables the golfer to stop the ball very near its landing position.
Multi-component balls are constructed with a cover and a core, wherein the core further comprises a center and an intermediate layer disposed concentrically between the center and the cover. The intermediate layer may be constructed as a solid layer or a wound layer, where a wound layer comprises many yards of elastic thread that are stretched and wrapped around the center. The core, comprising the center and intermediate layer, is encased within a durable cover material such as a SURLYN® or another similar material, or, alternatively, within a softer cover such as balata or polyurethane. Multi-component golf balls, especially those formed with a wound intermediate layer, are generally softer than a two-piece ball and can provide more spin, enabling a skilled golfer to exert more control over the ball's flight.
Golf ball centers incorporated within, e.g., multi-component balls may be solid or fluid-filled spheres. A variety of methods are known for forming fluid-filled centers, such as those disclosed in U.S. Pat. No. 5,836,831. The '831 patent discloses the use of thermoplastic polymers for forming spheres used in such fluid-filled centers. In the '831 patent, polyether-amide block copolymers are formed into hemispherical half-shells by compression or injection molding. The half-shells may be joined to form hollow spheres in a number of ways including welding, chemical bonding, RF heat sealing, induction bonding, hot wire seaming, co-injection molding or hot melt sealing. Alternatively, the center shell may be formed by extrusion blow molding, co-extrusion blow molding or injection blow molding.
The hollow center spheres are then filled with an appropriate fluid, generally an aqueous salt solution having a specific gravity of from about 1.0 to about 1.6, and preferably, about 1.25. Filling the hollow center spheres may be carried out by piercing the surface with a needle and injecting the fluid. The hole formed may be sealed in a number of ways including the application of adhesives that may be cured with heat or radiation, with solvent or water-based paints, hot melt adhesives or a polymeric material. A solid or wound layer is then applied around the fluid-filled center, using materials and methods well known in the art, to form a golf ball.
Permeation of water through one or more layers of a multi-layer golf ball may affect the properties or performance of that ball. Accordingly, one approach to obviating such water permeation has been to increase the hardness of the base polymer in the composition or blend used to form one or more golf ball layers. For example, different grades of PEBAX®, a polyether-amide block copolymer, demonstrate a decrease in water vapor permeability as the hardness of the grade increases (Elf Atochem, Philadelphia, Pa., technical bulletin: PEBAX®—
Basis of Performance
, page 18). However, such prior attempts to obviate the potential problem of water permeation across a golf ball layer, involving the incorporation of such harder polymeric materials into those layers, have generally led to unfavorable changes in the physical and performance characteristics of golf balls, such as increased compression and stiffness. In addition, although such harder materials are resistant to water permeation, it has been observed that the coefficient of restitution and initial velocity are both lower in balls formed with them. This has been especially problematic with respect to such compositions when employed in the formulation of hollow spheres used for assembly of fluid-filled centers.
Accordingly, there has thus been a long-felt need for golf balls formed with layers having improved resistance to water permeation wherein the materials relied upon for such purpose are capable of substantially preventing water permeation across one or more such layers without substantially affecting the overall physical and performance characteristics of the resultant golf ball. An additional constraint is found in the requirement that these materials should, nevertheless, be amenable to contemporary processes for the production of golf balls, and, more particularly, to the formation of hollow spheres used for the construction of fluid-filled centers. The present invention admirably meets these objectives.
OBJECTS OF THE INVENTION
An object of the present invention is to provide golf balls comprising one or more layers formed with compositions having improved resistance to water permeation while maintaining or even improving the performance characteristics of such balls.
Another object of the present invention is to provide polymer blend compositions comprising hydrophilic thermoplastic polymers and hydrophobic olefinic polymers that are incorporated within one or more layers of a golf ball, such that resistance to water permeation through such layers is substantially improved.
A further object of the present invention is the formation of hollow center shells used in the manufacture of fluid-filled centers for multi-component golf balls, from the blends disclosed herein, thereby substantially preventing fluid permeation across the center shell.
A particular object of the present invention is the provision of a wound golf ball having an improved resistance to water permeation, with a polyurethane, polyurea or epoxy-urethane cover and a fluid-filled center that includes a center shell formed from a blend of a polyether-amide or a polyether-ester block copolymer and a maleic anhydride grafted metallocene-catalyzed copolymer of ethylene and octene, a maleic anhydride grafted metallocene-catalyzed copolymer of ethylene and hexene, or a maleic anhydride grafted metallocene-catalyzed copolymer of ethylene and butene.
SUMMARY OF THE INVENTION
The present invention is directed, in a first embodiment, to a golf ball comprising at least one layer havin
Jones Douglas E.
Rajagopalan Murali
Acushnet Company
Gorden Raeann
Swidler Berlin Shereff & Friedman, LLP
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