EP2520696A1 - Synthetic fiber for artificial turf system - Google Patents

Abstract

Plastic fiber (2) for artificial turf covering comprises a first plastic component (4) and a second plastic component (6) embedded in the first plastic component, where the second plastic component exhibits a higher resilience than the first plastic component and is formed in the form of at least two strands (8a) extending in the longitudinal direction of the plastic fiber. The plastic fiber exhibits essentially a shape in cross-section having a first symmetrical axis and a second symmetrical axis extending perpendicular to the first axis of symmetry. Plastic fiber for artificial turf covering comprises a first plastic component (4) and a second plastic component (6) embedded in the first plastic component, where the second plastic component exhibits a higher resilience than the first plastic component and is formed in the form of at least two strands (8a) extending in the longitudinal direction of the plastic fiber. The plastic fiber exhibits essentially a shape in cross-section having a first symmetrical axis and a second symmetrical axis extending perpendicular to the first axis of symmetry, where the extension in the direction of the second symmetrical axis is less than the extension in the direction of the first symmetrical axis. An independent claim is also included for the artificial turf comprising a flat support and utilizable pile that is formed from pile threads connected with the support, where the pile threads of utilizable pile are formed at least partially from the plastic fiber.

Description

The present invention relates to a plastic fiber for an artificial turf.

The invention further relates to an artificial turf flooring and its use for a sports field or playground, in particular a football field.

Artificial grass is often used as an alternative to a natural lawn, especially on sports grounds and playgrounds. Compared to the latter, artificial turfs have the advantage that they have a higher load capacity and are relatively easy to care for. In addition, they are well playable compared to a natural lawn even in bad weather.

Corresponding artificial turf coverings comprise a turf formed by plastic pile threads which are mounted on a support.

An important requirement for the material of the pile yarns, in particular with regard to the use of the artificial turf covering for a football pitch, is to avoid skin burns even if the user or the football player glides over the artificial turf at a relatively high speed.

Typically, pile threads made of skin-friendly polyethylene are used, which minimizes the risk of skin burns.

However, polyethylene pile yarns in particular have the disadvantage that they have a relatively weak Have resilience. In order to avoid a "lying" of the individual pile threads of the artificial turf as possible, therefore, a relatively high density of pile threads per unit area is conventionally sought. This is to ensure that the individual pile threads are better supported by adjacent pile threads. Unfilled artificial turf therefore usually has a density of about 3,000 to 6,000 pile threads per square decimeter.

Artificial turf with such a high density of pile threads, however, has the disadvantage that they feel "brush-like" when entering and thus unnatural. Incidentally, the ball rolling behavior on such an artificial turf differs relatively strongly from that on a natural turf; As the ball rolls almost as though on a smooth surface and thus very fast, these synthetic turfs are often suitable not only for amateur sports but also for professional sports.

Due to the compared to a natural turf much higher Halmdichte said artificial turf also soften in the appearance relatively strong from a natural turf; they also look visually artificial, which further impairs their acceptance.

A possible concept for preventing mechanical damage and thus a "lying" of the pile threads is in EP-A-1696077 proposed. According to this publication, the pile threads following the support are surrounded by a support layer which adjoins the support. If a pile yarn is deflected from its original position, the support layer prevents the pile yarn from being deflected directly on the support. The Support layer thus limits the deflection of the pile threads and supports their provision.

Although artificial grass coverings according to EP-A-1696077 have proven to be advantageous, nonetheless, there is a need for a plastic fiber, with which regardless of the pile density or the presence of a support layer even with heavy use of the artificial turf offsetting the pile threads can be prevented.

Object of the present invention is thus to provide a natural grass blade as similar as possible synthetic fiber for an artificial turf covering which, while maintaining the surface properties - in particular the skin compatibility - known plastic fibers has a high resilience.

A further object of the present invention is to provide an artificial turf covering which constantly ensures optimal playability even under prolonged use and which is very close to a natural turf.

The object of the invention is solved by the subject matter of claim 1. Preferred embodiments are the subject of the dependent claims.

The present invention thus relates to a plastic fiber for an artificial turf.

According to the invention, the plastic fiber comprises a first plastic component and one in the first Plastic component embedded second plastic component.

The second plastic component in this case has a higher resilience than the first plastic component and is in the form of at least two extending in the longitudinal direction of the plastic fiber strands. These usually run parallel to each other.

Due to the fact that the second component has a higher resilience than the first plastic component, the resilience of the plastic fiber is increased overall; the strands of the second plastic component thus serve as a kind of "reinforcing strands" for the plastic fiber.

The term recovery is well known to those skilled in the art and refers to the ability of the plastic component or plastic fiber, after release of a force acting thereon, to retain the original, i. before or after the action of force completely or partially resume this form. As a rule, an increased resilience is due to an increased rigidity of the material.

Thus, according to the invention, a plastic fiber having a high recovery capability can be obtained without impairing the surface properties ensured by the first plastic component, and in particular its skin compatibility. Thus, the present invention allows two previously incompatible preferred properties of the plastic fiber, namely a good skin compatibility and a high resilience to combine with each other.

As will be explained in detail below, the plastic fiber of the present invention makes it possible to provide an artificial turf covering which constantly ensures optimum playability even under prolonged stress. In particular, due to the high resilience of the plastic fiber, a crop density can be selected which is relatively low and thus approximated to the crop density of a natural grass, without the pile yarns forming the grass pile remaining under heavy use of the artificial grass and thus impairing the sport-functional properties. Incidentally, it is achieved by the invention according to the reduction in Halmdichte that the artificial turf covering both a visual nature and in terms of ball rolling or ball rebound properties can be adjusted to a natural grass.

In contrast to plastic fibers, in which the second plastic component is present as a single strand, it has surprisingly been found according to the invention that in the presence of several strands of the second plastic component, a bending behavior can be obtained which is very similar to the bending behavior of a natural grass blade. Despite the high resilience of the inventive plastic fiber, a "brush-like" turf can thus be avoided.

In addition, due to the multi-strandedness of the second plastic component, there is a larger total surface area per total volume, which in turn allows better bonding with the first plastic component. Opposite in the DE-A-103 07 174 described multilayer monofilament is thus for the present invention no separate adhesion promoter layer needed for a sufficient composite of the two plastic components.

According to the invention, the plastic fiber has in cross-section a shape with a first axis of symmetry and a second axis of symmetry perpendicular to the first axis of symmetry, wherein the extent in the direction of the second axis of symmetry is less than the extent in the direction of the first axis of symmetry.

In this regard, it is preferred that the plastic fiber in cross section has the shape of a diamond with rounded corners.

By means of said cross-sectional shape, edges and thinnings are avoided, which additionally contributes to a high wear resistance of the plastic fiber. Incidentally, the described shape of the natural shape of a grass blade comes very close, which in the end further contributes to the fact that a corresponding artificial turf covering looks very similar to a natural turf.

In terms of optimum bending behavior, it is particularly preferred that the strands of the second plastic component are arranged at least approximately along the first axis of symmetry.

In contrast to the fibrillated flat films or tapes often used in common artificial turf coverings, the plastic fiber of the present invention is generally designed as a monofilament.

The dimensions of the plastic fiber usually correspond essentially to those of natural blades of grass; Preferably, the yarn count of the individual monofilaments is in the range of about 1'400 to 2'400 dtex.

According to a preferred embodiment of the present invention, the first plastic component comprises a polyolefin. In this regard, it is further preferred that the polyolefin is polyethylene and / or polypropylene, more preferably polyethylene. Said polyolefins, and in particular polyethylene, are particularly skin-friendly, so that skin burning can be effectively avoided even if the user glides over the turf at a relatively high speed, which is very often the case in football in particular.

Incidentally, according to a further preferred embodiment, the second plastic component comprises a polyamide. This has a very high resilience and is also preferred because of its very easy availability.

According to a further preferred embodiment, the number of strands of the second plastic component is 2 to 10, preferably 2 to 7, most preferably 5. According to this embodiment, the bending behavior of the plastic fiber can be additionally optimized.

Incidentally, it has been found that a brush type is not present or within an acceptable range if the strands of the second plastic component are arranged in cross-section at least approximately along a straight line. This ensures a degree of resilience with sufficient resilience of the plastic fiber, which also contributes to an optimized playability of the lawn.

The plastic fiber according to the present invention is usually produced by extrusion. In this case, the first plastic component is extruded simultaneously with the second plastic component, wherein a spinneret is used, which has a first opening for the first plastic component and a respective further opening for each strand of the second plastic component. Since the melting points of the first and the second plastic component generally differ from one another, the corresponding openings are generally tempered differently.

In particular, it is conceivable to use a spinneret which has a spinning opening with rhombus-shaped ("diamond" -shaped) cross-section for the first plastic component, in which further spinning openings with a circular cross-section are arranged for the second plastic component. If a plastic fiber extruded over such a spinneret is subsequently stretched, then a plastic fiber can be obtained which has the shape of a rhombus with rounded corners in cross-section. As stated above, such plastic fibers have particularly advantageous properties, in particular high wear resistance.

According to a further aspect, the invention further relates to an artificial turf covering comprising a flat carrier and a Nutzflor, which is formed from bonded to the carrier pile threads. The pile threads are at least partially formed from a plastic fiber as described above.

Due to the resilience of the plastic fiber used, the artificial turf flooring may have a relatively low and a natural turf approximated Halmdichte without the pile threads would also lie under heavy load.

Consequently, even with prolonged use of the artificial turf constant optimal playability and a natural turf very similar appearance can be guaranteed.

In particular, the ball roll behavior and ball rebound behavior can be matched to that on a natural turf and thus improved by the increased resilience of the plastic fiber according to the invention or the attainable reduction of the stem density. Thus, with appropriate Halmdichte the ball is braked by the plastic fiber according to the invention, which is particularly in the amateur field in terms of good playability of the artificial turf.

Incidentally, can be obtained by the inventively achievable reduced Halmdichte a confused Halmstellung, whereby the artificial turf can not only visually be adapted to a natural turf, but also ensures a uniform and direction-independent ball rolling behavior.

In addition, the cleaning of the turf is greatly simplified by the reduced Halmdichte because the pile threads for the usually used for cleaning rotating brushes are more easily accessible and thus can be freed of dirt on their entire surface.

Furthermore, by reducing the Halmdichte the amount of material required for the Nutzflor can be reduced, which on the one hand to a weight reduction and thus contributes to a simplified transportability of the artificial turf and on the other hand allows a reduction in material costs.

Incidentally, a high grip of the lawn can be ensured by the increased resilience and the resulting reduction in Halmdichte. This is particularly the case when the artificial turf covering has a base layer of polyamide fibers, as is the case with the Triple T Technology ™ synthetic turf specifically designed for use as football turf. When using the inventive plastic fiber in such an artificial turf covering can be ensured due to the increased resilience or the achievable reduction in Halmdichte that the cams or nubs of football boots optimally engage in the base layer, allowing faster and more powerful direction changes of the user or the football player allowed.

In addition, a base layer of polyamide fibers is also preferred because water is incorporated therein. On evaporation, this cools the utility pile of the synthetic turf, further minimizing the risk of major burns. In particular, when the polyamide fibers are crimped and thereby form a moss-like layer, a nearly optimal water storage is ensured by the base layer.

For the production of the artificial turf covering of the present invention, the pile threads are typically introduced by tufting in the carrier. In general, the pile threads are fixed by means of an applied on the underside of the carrier adhesive, such as water-resistant latex on the support. If, as in the above-mentioned preferred embodiment, a base layer of polyamide fibers is present, the straw group of the pile threads introduced in the tufting process are preferably wound by a polyamide monofilament, whereby an additional anchoring of the pile threads is ensured.

The artificial turf covering of the present invention is visually very close to a natural turf especially if the length of the pile tufts of the utility tuft is from the top of the trough measured in the range of about 2.5 to 4 cm.

With regard to an appearance which is as similar as possible to a natural turf, it is otherwise preferred that a first part of the pile threads of the utility pile be measured longer from the upper side of the support than a second part of the pile threads of the utility pile. The shorter pile threads of the utility pile mimic the regrowing blades of a natural grass. Incidentally, in this embodiment further preferred ball roll and ball rebound properties result. Thus, by the longer, less dense pile threads of the Nutzflors exerted an increased braking effect on the ball, which is in the sense of good playability of the artificial turf. With regard to the mentioned embodiment, it is particularly preferred that the pile threads of the first part be longer by about 5 to 10 mm than the pile threads of the second part.

According to a preferred embodiment, the Nutzflor on its side facing away from the carrier has a density of less than 1'400 pile threads per square decimeter, which ensures almost optimal optical properties and excellent playability of the artificial turf. The density of this preferred embodiment is thus considerably lower than the density of 3,000 to 6,000 pile threads per square decimeter, which is usually required for known synthetic turf coverings, depending on the material.

The artificial turf flooring of the present invention can be used for both unfilled systems, such as in the EP-A-1696077 described for filled systems, such as in the US 2001/0033902 described or for so-called hybrid systems, ie systems which have only a plastic granulate layer, such as in the European patent application no. 09014780 described, are used. Since the advantages of the present invention become particularly apparent in unfilled systems, the artificial turf covering is preferably unfilled.

In addition to the use of artificial turf flooring for a sports field or playground is also conceivable to use the artificial turf flooring for a decorative or landscaping lawn, as he finds in the private, object or event area application. In this regard, in particular, the use of the artificial turf flooring according to the invention in road construction, e.g. in roundabouts, mentioned.

The invention is based on the appended FIG. 1 further illustrated. This represents a purely schematic one Cross-sectional view of a plastic fiber according to the invention.

The plastic fiber 2 shown in the figure has in cross-section substantially the shape of a rhombus with rounded corners. The rhombus defines a first axis of symmetry, cross-sectional major axis A, and a second symmetry axis extending at right angles thereto, cross-sectional secondary axis B. The extent in the direction of the cross-sectional secondary axis B is less than the extent in the direction of the cross-sectional main axis A.

As can be seen from the figure, the plastic fiber 2 comprises a first plastic component 4 and a second plastic component 6 embedded in the first plastic component, wherein the second plastic component has a higher resilience than the first plastic components. Preferably, the first plastic component comprises a polyolefin and the second plastic component comprises a polyamide. In the embodiment shown, the second plastic component 6 is in the form of five strands 8a, 8b, 8c, 8d, 8e extending in the longitudinal direction of the plastic fiber. The strands 8a-8e have a substantially circular shape in cross-section and are arranged along the main axis A.

The shape of the synthetic fiber and the number and shape of the strands of the embodiment shown in the figure are intended to be purely exemplary and can be adapted by the skilled person depending on the result to be achieved.

Claims (15)

Plastic fiber for an artificial turf covering
a first plastic component (4) and
a second plastic component (6) embedded in the first plastic component (4),
wherein the second plastic component (6) has a higher resilience than the first plastic component (4) and in the form of at least two extending in the longitudinal direction of the plastic fiber strands (8a-8e), characterized in that the plastic fiber in cross-section substantially a shape with a first axis of symmetry (A) and a second axis of symmetry (B) extending at right angles to the first axis of symmetry, the extent in the direction of the second axis of symmetry (B) being less than the extent in the direction of the first axis of symmetry (A). Plastic fiber according to claim 1, characterized in that the first plastic component (4) comprises a polyolefin, in particular polyethylene and / or polypropylene. Plastic fiber according to one of the preceding claims, characterized in that the second plastic component (6) comprises a polyamide. Plastic fiber according to one of the preceding claims, characterized in that the number of strands of the second plastic component (6) is 2 to 10, preferably 2 to 7, most preferably 5. Plastic fiber according to one of the preceding claims, characterized in that the strands (8a-8e) of the second plastic component (6) are arranged in cross-section at least approximately along a straight line. Plastic fiber according to one of the preceding claims, characterized in that the strands (8a-8e) of the second plastic component (6) is arranged at least approximately along the first axis of symmetry (A). Plastic fiber according to one of the preceding claims, characterized in that it has the shape of a rhombus with rounded corners in cross section. Artificial turf covering comprising a flat carrier and a Nutzflor, which is formed from bonded to the carrier pile threads, characterized in that the pile threads of the Nutzflors are at least partially formed of a plastic fiber (2) according to one of the preceding claims. Artificial turf covering according to claim 8, characterized in that the length of the pile threads of the Nutzflors measured from the top of the wearer in the range of 2.5 to 4 cm. Artificial turf covering according to claim 8 or 9, characterized in that a first part of the pile threads of the Nutzflors measured from the top of the wearer is longer than a second part of the pile threads of the Nutzflors. Artificial turf covering according to claim 10, characterized in that the pile threads of the first part are longer by 5 to 10 mm than the pile threads of the second part. Artificial turf covering according to one of claims 8 to 11, characterized in that the Nutzflor on its side facing away from the carrier has a density of less than 1'400 pile threads per square decimeter. Artificial turf covering according to one of claims 8 to 12, characterized in that it also has a base layer of polyamide fibers. Artificial turf covering according to one of claims 8 to 13, characterized in that it is unfilled. Use of the artificial turf covering according to one of claims 8 to 14 for a sports field or playground, in particular a football field.

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