Stock material or miscellaneous articles – Three dimension imitation or 'treated' natural product – Flora
Reexamination Certificate
2003-08-05
2004-10-05
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Three dimension imitation or 'treated' natural product
Flora
C428S085000, C428S087000, C428S143000, C428S147000, C428S149000, C428S150000, C405S036000
Reexamination Certificate
active
06800339
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to synthetic turfs for athletic fields and, more particularly, to a synthetic turf filled with particulate material so as to give the field stability and resiliency.
BACKGROUND OF THE INVENTION
A natural grass turf covering has traditionally been cultivated on playing surfaces for athletic games or events. In addition to looking good, natural grass turf provides inherent resiliency and cushioning, thereby minimizing the risk of injury due to an athlete's impact with the turf. Such natural grass turf coverings have traditionally been used to cover American football or soccer fields. Many athletes participating in these high impact sports desire a surface with a high degree of resiliency such as is provided by a natural grass turf covering.
However, maintenance of natural grass turf on athletic playing areas can be expensive and time consuming. Natural grass does not grow well within shaded areas like those within indoor or partially enclosed stadiums. In addition, some “heavy traffic” locations on the playing field are susceptible to wearing out or deteriorating due to continuous or excessive wear. These worn areas may become muddy and slippery after the natural grass dies, increasing the likelihood of injury.
Therefore, various types of synthetic turf have been developed and installed on athletic playing surfaces, particularly surfaces located within indoor stadiums. Generally, these various synthetic turf surfaces reduce the expense of maintaining athletic playing surfaces and increase the durability of the turf surface. Synthetic turf generally comprises a flexible backing and a plurality of grass-like pile filaments or fibers extending upwardly from the backing. The flexible backing is typically laid on a foundation or compacted substrate, such as crushed stone or stabilized base material.
Most earlier forms of synthetic turf relied solely on the backing and the pile filaments or fibers as the playing surface. ASTROTURF synthetic turf is an example of this type of artificial turf.
In order to give the synthetic turf a desired degree of resiliency and stability, various formulations of granular fill material may be placed between or among the upstanding pile filaments of the synthetic turf. This granular fill material extends upwardly from the upper surface of the backing to a height below the tops of the pile filaments, thereby leaving upper portions of the pile filaments exposed for aesthetic purposes, among others. The granular fill material helps maintain in a substantially upright condition the filaments of the synthetic turf. This granular fill material has been sand, crushed slag particles, resilient foam, crumb rubber particles, sand or various combinations thereof.
U.S. Pat. No. 3,995,079 discloses a filled synthetic turf for golf greens, the granular fill material being granulated coal slag, crushed flint or crushed granite. The difficulty with the use of these particles as fill material is that they are very abrasive. This inherent abrasiveness increases the probability of scrapes or abrasions to persons falling upon the filled synthetic turf.
U.S. Pat. No. 4,044,179 discloses a filled synthetic turf for athletic playing surfaces, wherein the granular fill material is sand with a small amount of moisture retaining material. The difficulty with the use of sand as the fill is that sand compacts over time and use, resulting in a filled synthetic turf which is harder than desired. Because such playing surfaces are commonly used for high impact sports, the harder the field, the greater the likelihood of injury for the players using the field. Another difficulty with sand as the fill material is that sand retains water or moisture, thereby increasing the susceptibility of the filled synthetic turf to mold or mildew.
U.S. Pat. No. 4,337,283 discloses a filled synthetic turf for athletic playing surfaces, the granular fill material being a uniformly mixed combination of sand particles and resilient particles. One inherent difficulty with the use of such a mixture is that the resilient particles of the mixture tend to migrate to the top of the fill layer over time and repeated use with the sand tending to settle below the resilient particles. The sand that settles to the bottom of the fill layer tends to compact over time and use. This ultimately results in a layered synthetic turf which is harder and more abrasive than desired. A further disadvantage of such a uniformly mixed in fill is that some abrasive sand particles remain on the top surface of the synthetic turf. Players who come into contact with the sand particles experience skin abrasions.
U.S. Pat. No. 5,958,527 discloses a filled synthetic turf for athletic playing surfaces, the granular fill material comprising separate layers of sand particles and resilient particles. Difficulties with such a layered mixture are over time and repeated use, the sand at the bottom of the mixture tends to compact, causing the field to harden and inhibiting the vertical drainage of water off the field through the backing fo the filled synthetic turf.
Because filled synthetic turfs are subject to large temperature fluctuations, resulting in contraction and expansion of the turf backing, a fill comprising at least one layer of sand stabilizes the backing of the synthetic turf and provides weight to minimize lateral movement of the backing. However, over time and use, the sand particles are churned up or migrate toward the top of the field. The resilient particles in known filled synthetic turfs may migrate laterally due to the dynamic nature of the fill material. Athlete's cleats and other wear churns or mixes the fill material, resulting in a non-uniform playing surface with areas of exposed sand. Abrasive sand particles migrate to or find their way to the surface of the synthetic turf between the pile filaments. Whenever athletes fall or contact the turf, they are subject to cuts or abrasions due to the sand. The sand particles located at the surface of the fill material also are abrasive to the pile filaments of the synthetic turf, thereby degrading and/or fibrillating the tops of the pile filaments over time.
In addition, over time the sand compacts and becomes harder, an undesirable quality for a synthetic playing surface. Then, the resilient effect of the rubber particles is only temporary.
Therefore, it is an object of this invention to hold down the backing of a filled synthetic turf while eliminating the adverse effects of the use of sand.
It is another object of the present invention to extend the life of the resilient characteristics of a filled synthetic turf while still maintaining a high degree of directional stability for the synthetic backing.
It is still another object of the present invention to attain a long lasting, uniformly resilient athletic playing surface at a relatively low cost, and which is sufficiently versatile in design to accommodate a number of potential structural enhancements.
SUMMARY OF THE INVENTION
The present invention accomplishes these objects for a filled synthetic turf by using a particulate fill comprising at least some particles other than sand, i.e. particles such as gravel, to serve as a “ballast” to hold down the backing. In one aspect of the present invention, the filled synthetic turf has a multi-layered particulate fill, the lower layer being a heavy particulate such as gravel, to serve as a “ballast” to hold down the backing with an upper layer of resilient particles such as rubber over the ballast layer.
The filled synthetic turf comprises a backing residing on a foundation; a plurality of grass-like pile filaments secured to the backing and extending generally upwardly therefrom and a particulate fill material residing on the backing. The foundation may be crushed stone, dirt, asphalt, concrete, a pad or any other supporting surface. For drainage purposes, one or more drainage members may comprise part of the foundation.
The backing is preferably a flexible, water permeable material but may be made of any desired material.
Heinlein Mark A.
Linville Stephen L.
Motz Joseph E.
Boss Wendy
Coevin Licensing, LLC
Jones Deborah
Wood Herron & Evans L.L.P.
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