Patent Application
20120156401
The invention relates to an artificial fiber of the monofilament-type for use in an artificial grass sports field wherein, seen in a transverse sectional direction of the fiber, at least part of the fiber is provided with stiffness-enhancing portion extending in the longitudinal direction thereof.
The invention also relates to an artificial grass lawn suitable for sports fields, consisting at least of a substrate to which one or more artificial fibers according to the invention are attached.
Many sports, such as field hockey, tennis, American football, etc., are now played on artificial grass sports fields, which sports fields are composed of an artificial grass lawn on which artificial fibers are provided. Although athletes sustain fewer injuries on a natural grass sports field when falling or making a sliding tackle, on account of the softer surface thereof, such sports fields are often severely damaged when the above sports are played thereon, precisely because they are used intensively and because of the varying influence of the weather conditions.
A drawback of the artificial fibers that are currently known is that they attend to assume a flat orientation relative to the ground surface after being played on. This results in so-called “bare patches” in the artificial grass sports field and thus in an increased risk of injuries, etc.
This problem can be eliminated in part, for example, by providing a granular infill material such as sand or granules of a plastic material between the artificial fibers. The presence of these infill granules leads to a more upright orientation of the artificial grass fibers. In addition, the infilled grains provide a softer, shock-absorbing playing surface on which players are less prone to injury. Furthermore, they provide improved playing characteristics, so that the playing characteristics of artificial grass sports fields resemble those of natural grass sports fields as much as possible.
The use of an infill in artificial grass sports fields, however, has a number of drawbacks. Not only is the construction of such an artificial grass sports field more labor-intensive than the construction of a natural grass sports field, but an artificial grass sports field provided with an infill requires subsequent maintenance as well. The initially uniform distribution of the granular infill can be disturbed by intensive usage. As a result, areas containing hardly any infill may form in places where the field is played on very intensively, for example, in the goal area. This has an adverse effect on the quality of play, which can lead to an increased risk of injury.
Another solution to the problem as described above is to increase the stiffness of the monofilament by changing the chemical composition and/or the processing method thereof. This is undesirable, however, because it will lead to a more abrasive artificial grass sports field with an increased risk of injuries.
A further solution to the problem as described above is to adapt the geometry of the artificial fiber, for example, as proposed in U.S. 2001/033902 or in WO 2005/005730. Both patent documents disclose fibers provided with stiffness-enhancing means. However, on account of the geometry of the fiber and the location of the stiffness-enhancing means, the artificial fibers that are obtained exhibit an increased risk of splitting and/or fracture as a result of material stresses that may be set up in the fiber, for example, due to loads exerted thereon during play or temperature changes that may occur.
It is also noted in this connection that U.S. 2001/033902 discloses a composite filament fiber (also called multifilament) which, on account of the geometry and the orientation of the stiffness-enhancing means, specifically provides weak lines of fracture in the composite fiber. The fiber is required to split in that case to create multiple filament fibers.
Similar weak artificial fibers that are liable to split and/or fracture are disclosed in WO 2005/005730. That publication also discloses a fiber comprising stiffness-enhancing means, but the fiber, on account of its geometry, has undesirable points or lines of fracture at which undesirable material stresses may be set up, for example, due to loads being exerted thereon during play (sliding tackles, etc.) or temperature changes that may occur.
It is one object of the present invention to avoid such a weak artificial fiber that remains susceptible to splitting and fracture, and to provide an improved artificial fiber for use in an artificial grass sports field, which fiber is provided with stiffness-enhancing portion. The fiber is less flexible, on account of the geometry of the fiber, exhibits less tendency to assume a flat orientation or to split or fracture, and furthermore does not exhibit an increased risk of injuries or have an adverse effect on the playing characteristics.
According to the invention, the artificial fiber comprises at least two fiber flange portions, at least one fiber flange portion forming the stiffness-enhancing portion, while at least two fiber flange portions have a uniform thickness.
More specifically, the stiffness-enhancing portion extends the full length of the fiber. On the other hand, the stiffness-enhancing portion can extend at least partially in the transverse sectional direction.
In another embodiment, the stiffness-enhancing portion is configured as at least one fiber flange portion extending at an angle to the plane formed by the fiber. The at least one fiber flange portion extends at an angle of about 90 degrees or about 45 degrees to the plane formed by the fiber in that embodiment.
In other embodiments, the at least one fiber flange portion is straight, curved or spiral-shaped.
The invention will now be explained in more detail with reference to the drawings, in which:
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
While the fiber flange portions 70a-70c extend in a star-shaped, albeit curved, manner with respect to the longitudinal axis 72 in
It is noted that the artificial fiber shown in
In spite of the use of less flexible artificial fibers that, according to the invention, include stiffness-enhancing portions incorporated in the fiber, it has become apparent that the risk of injuries does not significantly increase and furthermore that the playing characteristics of an artificial grass sports field comprising such artificial fibers 10-100 are not adversely affected.
It is also pointed out that the embodiments shown in
In addition, the fiber flange portions 30a-30b; 40a-40b; 50a-50b; 60a-60b and 70a-70b in
In another embodiment, as shown in
The foregoing description and the accompanying drawings are illustrative of the present invention. Other variations and arrangements are possible without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1028224 | Feb 2005 | NL | national |
This application is a continuation of U.S. Ser. No. 11/883,434, filed March 13, 2008 as the National Stage of PCT/NL2006/000057 filed Feb. 3, 2006 claiming the priority of NL1028224, filed Feb. 8, 2005, the entire disclosures of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11883434 | Mar 2008 | US |
| Child | 13402063 | US |
