Games using tangible projectile – Golf – Ball
Reexamination Certificate
2000-08-21
2002-10-01
Sewell, Paul T. (Department: 3711)
Games using tangible projectile
Golf
Ball
C473S357000, C473S351000, C473S354000
Reexamination Certificate
active
06458046
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a multi-layer, wound golf ball, especially one with the combined performance characteristics of both a wound and solid construction. In particular, the present invention relates to a golf ball with a wound thread layer disposed between the cover and a core, which comprises a center and an intermediate layer disposed about the center.
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 for a reasonable price while also providing maximum distance. Two piece solid balls are typically 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 helps impart a high initial velocity to the ball, which results in improved distance. In addition, this combination provides balls having a relatively low spin rate, which tends to provide greater driver distance.
At the present time, however, the wound ball generally 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 yarn are wrapped to form a wound core. Typically, the tensioned elastic thread is made of synthetic polyisoprene or natural rubber. For example, U.S. Pat. Nos. 5,674,137; 5,716,293; 5,816,937; 5,816,940; 5,816,941; 5,816,942; 5,888,151; and 5,976,034 relate to multi-layer, wound golf balls containing rubber thread windings. 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.
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. Some balls, however, have used two or more different threads of different dimensions to form the wound core. In this case, the innermost thread may be wound at a different tension and with a different pattern than the outermost thread. Furthermore, the outermost thread is generally wound in a more open pattern to form larger gaps between the thread, which helps ensure good amalgamation between the cover and the wound core.
The United States Golf Association (US GA) 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 (m/s), 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 off the tee, which requires a high initial velocity upon impact. Therefore, in an effort to meet the demands of the marketplace while providing conforming balls, manufacturers typically 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 enhance short iron shots, as well.
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 load. A ball with a higher compression feels harder than a ball of lower compression. 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 using short-iron shots than many non-wound balls. Particularly with approach shots into the green, the typically higher spin rate of soft covered, wound balls enables many golfers 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 when struck with a driver. 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 and the cover formulation process can affect the thickness of the cover, but other factors related to the cover will also affect this thickness.
It is known in the art to modify conventional solid balls by altering the typical single layer core and single cover layer construction to provide a multi-layer ball having such as a dual cover layer and/or a ball having a mantle layer disposed between the cover and the core. Like the solid cores, various cover layers and mantle layers are typically formed of polybutadiene that is chemically crosslinked with zinc diacrylate and/or similar crosslinking agents. The playing characteristics of multi-layer balls, for example compression, can be tailored by varying the properties of one or more of these mantle layers, also known as intermediate layers.
A number of patents are directed towards modifying the properties of layers used in forming conventional solid balls, multi-layer balls having two or more cover layers, dual core layers, such as those having a mantle layer disposed between the cover and center, and/or wound balls. For example, U.S. Pat. Nos. 5,674,137; 5,816,937; 5,816,942; and 5,885,172 are directed to multi-layer wound golf balls having multi-layer covers. For example, U.S. Pat. Nos. 3,147,324; 5,816,937; and 5,885,172 are directed to golf balls, or methods for making such, having a polyurethane outer cover. For example, U.S. Pat. Nos. 5,716,293 and 5,020,803 are directed to wound golf balls having a dual layer liquid core.
U.S. Pat. No. 5,020,803 to Gendreau et al. discloses a golf ball containing a liquid-filled center, surrounded by a heavy-walled sphere, around which a wound layer is disposed to form a wound core. The heavy-walled sphere is preferably rubber and is between 0.16 and 0.64 cm thick.
British Patent No. GB 2337706 A to Sumitomo Rubber Industries, Ltd. discloses a multilayer wound golf ball having a dual layer center, both layer being formed from the same materials. The diameter of both center layers are limited, as are the JIS-C hardnesses, and cover is made from a thermoplastic material.
Polyurethane is the product of a reaction between a polyurethane prepolymer and a curing agent. The polyurethane prepolymer is a product formed by a reaction between a polyol and a diisocyanate. The curing agents used previously are typically diamines or glycols. A catalyst is often employed to promote the reaction between the curing agent and the polyurethane prepolym
Fletcher Brian R.
Halko Roman D.
Acushnet Company
Hunter Alvin A.
Sewell Paul T.
Swidler Berlin Shereff & Friedman, LLP
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