Games using tangible projectile – Golf – Ball
Reexamination Certificate
2000-02-04
2002-11-05
Sewell, Paul T. (Department: 3711)
Games using tangible projectile
Golf
Ball
C473S351000, C473S356000, C473S354000
Reexamination Certificate
active
06475104
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to golf balls including a core having at least one wound layer and a cover disposed thereabout, and more particularly to wound golf balls having a wound core construction incorporating a solidified liquid material, such as a thermoplastic or thermoset polymer, therein.
BACKGROUND OF THE INVENTION
Conventional golf balls can be divided into two general types or groups: solid balls and wound balls. The difference in play characteristics resulting from these different types of constructions can be quite significant.
Solid balls with a two-piece construction are generally most popular with the average recreational golfer, because they provide a very durable ball while also providing maximum distance. Two piece solid balls are made with a single solid core, usually made of a crosslinked rubber, which is encased by a hard cover material. The combination of the core and cover materials, which are very rigid, provide a hard feel for the ball when it is struck with a club and provide a ball that is virtually indestructible by golfers. This combination of materials imparts a high initial velocity to the ball, which results in improved distance. In addition, due to this combination these balls have a relatively low spin rate which provides greater distance.
At the present time, however, the wound ball remains the preferred ball of 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 tensioned elastic thread or yam are wrapped to form a wound core. The wound core is then typically covered with a durable cover material, such as a SURLYN® or a similar material, or a softer “performance” cover, such as balata or polyurethane. The cover material adheres to the wound core.
Typically, a single strand of thread is employed in forming the wound core. This thread can be wrapped at variable tension as disclosed in U.S. Pat. No. 4,783,078 issued to Giza. Some balls, however, have used two different threads of different dimensions to form the wound core. In this case, the inner most thread may be wound at a different tension and with a different pattern than the outer most thread. Furthermore, the outer most thread is generally wound in a more open pattern to form larger gaps between the thread to assure good amalgamation between the cover and the wound core.
The United States Golf Association (USGA), the organization that sets the rules of golf in the United States, has instituted a rule that prohibits the competitive use in any USGA sanctioned event of a golf ball that can achieve greater than an initial velocity of 76.2 meters per second (mis), or 250 ft/s, when tested in a standardized device operated by the USGA (referred to hereinafter as “the USGA test”). An allowed tolerance of 2 percent, however, permits manufacturers to produce golf balls that achieve an initial velocity of up to 77.7 m/s (255 ft/s).
Players generally seek a golf ball that delivers maximum distance, which requires a high initial velocity upon impact. Therefore, in an effort to meet the demands of the marketplace, manufacturers strive to produce golf balls with initial velocities no greater than that permitted by the USGA test. Manufacturers try to provide these balls with a range of different properties and characteristics, such as spin and compression.
To meet the needs of golfers having varying levels of skill, golf ball manufacturers are also concerned with varying the compression of the ball, which is a measurement of the deformation of a golf ball under a fixed load. A ball with a higher compression feels harder than a ball of lower compression. With initial velocities in the range of 245 to 255 ft/sec in the USGA test, wound golf balls generally have lower compression and spin characteristics that are preferred by better players. Whether wound or solid, all golf balls become generally more resilient (i.e., have higher initial velocities) as compression increases. Manufacturers of both wound and solid construction golf balls must balance the requirement of higher initial velocity from higher compression with the desire for a softer feel from lower compression.
Wound balls typically enable a skilled golfer to have more control over the ball's flight and final position than many non-wound balls. Particularly with approach shots into the green, the typically higher spin rate of soft covered wound balls enables the golfer to stop the ball very near its landing position. Soft covered wound balls with their lower compression, however, tend to exhibit a lower initial velocity than hard covered solid balls. This characteristic, in combination with a higher spin rate than solid balls, means wound balls generally display shorter distance than hard covered solid balls. The advantages of wound constructions over solid ones, however, are more related to spin and controllability than distance.
A softer feel is the result of a lower compression, but feel is also affected by cover hardness and thickness. In wound constructions, a thinner cover will have a softer feel, so manufacturers often strive to produce balls with the thinnest possible covers. The packing density of the windings affects the thickness of the cover, but other factors related to the cover will also affect this thickness.
Some manufacturers dip wound cores in a latex material. A light application of latex is applied to wound cores to improve cover quality or to ensure that cores or wound layers do not unravel. For example, in balls whose covers are formed in a liquid casting process, such as U.S. Pat. Nos. 5,006,297 and 5,733,428, the conventional wound cores are submerged to obtain a light application of latex material prior to covering. A “light application” of latex material is obtained with a particular combination of percentage solids applied using a particular submersion time. For a light latex application, the greater the percentage of solids, the shorter the submersion time, and when the percentage of solids decreases the submersion time can increase. For example, a light latex application can be accomplished using a latex of about 5% solids applied using a submersion time of less than eight seconds, as disclosed in U.S. Pat. No. 5,006,297. Also, a light latex application as disclosed in U.S. Pat. No. 5,733,428 is accomplished using a latex of about 30%-60% solids that is applied using a submersion time of less than eight seconds. A “heavier” latex application on the outer surface of the wound core reduces the amalgamation of the cover with the windings. Thus, an excessive application of latex on the outer surface of the wound core interferes with core-cover adhesion decreasing cover durability.
Another purpose of this light latex application is to seal in any air trapped between the innermost threads. If the air is not trapped, it can rise to the surface of the cover during the covering process and form air bubbles. Since these air bubbles are visible through the cover, they are undesirable imperfections in the golf ball and may result in reduced durability. As discussed above, however, a heavier application of the latex material can be problematic since it may, for example, decrease adhesion of the cover material to the wound core.
Additional references disclose other variations of a rubber or latex used with a thread layer, such as U.S. Pat. No. 4,272,079 that discloses a wound ball including a single wound thread layer over a center forming a wound core. This wound core is covered with a latex-containing ionomer resin that coats the surface of the thread layer. A cover is formed on the core. Since the latex and cover are formed with ionomer resin, an adhesive bond is formed therebetween. The ionomer latex improves the adhesion between the cover and the wound layer.
U.K. Patent No. 1,021,424 discloses a wound ball that includes a center and a rubber tape layer wound on the center. The ball further includes a first layer of rubber thread wound on the tape layer. This forms a wound core,
Bissonnette Laurent
Halko Roman D.
Lutz Mitchell E.
Acushnet Company
Hunter, Jr. Alvin A.
Sewell Paul T.
Swidler Berlin Shereff & Friedman, LLP
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