EP2129834B1

EP2129834B1 - Artificial lawn

Info

Publication number: EP2129834B1
Application number: EP08723865.5A
Authority: EP
Inventors: Peter Van Reijen
Original assignee: Tapijtfabriek H Desseaux NV
Current assignee: Tapijtfabriek H Desseaux NV
Priority date: 2007-03-29
Filing date: 2008-03-26
Publication date: 2013-05-15
Anticipated expiration: 2028-03-26
Also published as: NL1033613C2; WO2008120974A1; EP2129834A1

Description

The present invention relates to an artificial lawn, whose substructure comprises a substrate layer of artificial grass fibres and one or more layers present under said substrate layer.
Such a substructure is known per se from Dutch patent No. 1016193 in the name of the present applicant, In which the artificial lawn essentially consists of three separate layers, viz. a lower drainage layer consisting of gravel for effecting an adequate drainage of excess rain water. Present on top of said drainage layer is a base course consisting of earth, for example, whilst finally a layer of artificial grass fibres is present on top of said base course, which artificial grass fibres have been tufted to a blacking layer. Finally, an upper course may be present between the artificial grass fibres, which upper course will essentially consist of sand and/or rubber, which rubber functions to give the surface a resilient feel, whilst the sand provides a dense packing and thus an adequate fixation of the artificial grass fibres.
WO0196664 relates to an artificial grass lawn suitable for sports fields, which artificial grass lawn consist of a base layer, on which first artificial grass fibers are disposed wherein said base layer comprises a material having damping properties. The base layer has a closed structure or an open structure and is made of a rubber or a synthetic foam product.
Artificial lawns have been known for many years, with field hockey being one of the most frequently practised sports on artificial grass. Also soccer, rugby, tennis, skling and golf may be mentioned In this connection.
Since 2004 FIFA and UEFA have officially approved of the use of artificial turf for soccer matches. In spite of this support from the official soccer authorities, the degree of acceptation of artificial turf among soccer players, clubs and local authorities Is still insufficient. Artificial turf Is still found to exhibit technical problems such as:i) risks of injury related to impact and fatigue (shock absorption, energy restitution, depression of the surface), ii) risks of Injury upon starting and stopping, sudden changes in direction (grip, slip, traction), iii) risk of bums and grazes due to skin contact when making sliding tackles, and iv) the length of the ball roll and artificial lawns exhibiting too much shrinkage (material properties).
One aspect of the present invention is therefore to optimise the sports characteristics of artificial lawns.
Another aspect of the present invention is to provide a substructure for artificial lawns which leads to a reduction of the number of injuries among sporters.
Another aspect of the present invention is to provide a substructure for an artificial lawn which minimises the maintenance costs.
Another aspect of the present Invention is to provide a substructure for an artificial lawn wherein impact- and fatigue-related problems are minimised.
The substructure as referred to in the introduction is characterised by the characterizing portion of claim 1.
The present inventors have found that when such a gel layer is used, a substructure of an artificial lawn is obtained which exhibits good results as regards impact- and fatigue-related properties, so that the occurrence of chronic injuries resulting form walking on artificial lawns is minimised. Moreover, it has been found that players tire less easily when such a substructure of an artificial lawn is used. The term "uniform" is to be construed such that the gel layer has a homogeneous structure not comprising any separate, gel-containing compartments.
Although an artificial lawn in which a gel material is used directly below the backing layer of the artificial grass fibres is known from U.S. Pat. No. 2006/0040073 A showing the features of the preamble of claim 1, the gel layer used in said US patent is essentially different from that of the present application, because the gel layer used is said US patent is present in separate, flexible containers, whilst the gel layer used In the present substructure extends as a uniform gel layer over substantially the entire dimension of the substrate layer. Since separate, flexible containers are used as gel units In the aforesaid US patent, resilient characteristics essentially different from those of the gel container itself will be obtained at the points of contact between such separate containers, as a result of which the risk of injury is undesirably increased.
In a special embodiment of the present invention, the uniform gel layer directly abuts against the substrate layer, so that the resilient characteristics of the uniform gel layer are optimally utilised.
In another embodiment being not part of the present invention it is desirable that a uniform gel layer be present on the substrate layer on the side remote from the layers present under the substrate layer, which gel layer extends over substantially the entire dimensions of the substrate layer, with the artificial grass fibres extending through the gel layer in a direction away from the substrate layer.
In such an embodiment, the uniform gel layer is in fact present on the playing side of the substrate layer of artificial grass fibres, and the gel layer must in particular be a uniform gel layer, which means that the gel layer must not be divided into separate compartments.
Using the aforesaid gel layer it is possible to adapt the sports characteristics of the substructure, In which connection it is in particular desirable for the energy restitution, determined over the entire substructure, to range from 20-40, measured according to EN 15330, 2007. For adequate sports characteristics It is particular desirable that the shock absorption, measured over the entire substructure, has a value of at least 20 %, measured according to EN 16330, 2007.
The gel layer is made up of a polyurethane-based gel, in particular an MDI polyether polyol-based system, which gel preferably has a hardness of 0-50, measured according to Shore 00.
the gel layer
The thickness of the gel layer that is used ranges from 2-10 mm, in particular 2-6 mm, which thickness is determined by the special location of the gel layer, viz. on the playing side or under the substrate layer of artificial grass fibres. The density of the gel layer in particular ranges from 250-560 kg/m².
In a special embodiment a so-called infill may be present between the artificial grass fibres on the playing side of the substructure, for which purpose a combination of sand and/or rubber has already proved to be suitable. In a special embodiment, however, the loose infill may also be built up of gel granules. One or more additional properties may be imparted to the aforesaid granular material, its water absorbing capacity, for example, can be advantageously influenced by making use of naturally absorbent materials. Suoh an aspect is in particular advantageous if the present substructure is used for playing hockey, because with the current prior art lawns the field is practically completely inundated, which leads to a large water consumption. The International Hockey Federation (FIH) has already indicated its intention to ban fields exhibiting a large water consumption in the future.
In a special embodiment, at least one of the layers present under the substrate layer is composed of a material selected from the group consisting of asphalt, lava, fly ash, sand, rubble, clay granules, foamed concrete and road-metal, or a combination thereof. Another possibility is to use a layer comprising a matrix of a plastic foil with chambers present therein, which chambers contain a fluid, in particular air. Furthermore it is possible to use a foam layer. In a special embodiment it is furthermore desirable that a honeycomb structure be present under the substrate layer, which honeycomb structure has a harmonica configuration and which is made up of a series of substantially identical cells arranged in rows, which cells have lateral cell walls arranged adjacent to each other in an annular configuration, forming cell openings after the harmonica configuration has been expanded. Such cell openings are adjacent to the substrate layer and/or the gel layer at their upper side.
Although the description of the present application has so far been based on a substrate layer built up of artificial grass fibres, it is also possible in a special embodiment for the substrate layer to comprise natural fibres such as grass, but also cotton, flax, sisal, hemp, jute, silk, wool and bamboo in addition to artificial grass fibres.
The present invention will now be explained in more detail by means of a number of examples, in which connection it should be noted that the present invention is by no means limited to such special examples.
Figure 1 schematically shows a substructure 5 comprising a substrate layer 1 in which artificial grass fibres 2 are present, which substrate layer 1 is arranged on top of a uniform gel layer 3, which extends over substantially the entire dimensions of the substrate layer 1. One or more further layers (not shown) may be present under the gel layer 3. The thickness of the gel layers preferably ranges from 6-10 cm.
Figure 2 shows a substructure 6 being not part of the present invention, comprising a substrate layer 1 in which artificial grass fibres 2 are present, which artificial grass fibres 2 have been tufted through a gel layer 3 arranged on top of the substrate layer 1. The thickness of the gel layer 3 preferably ranges from 2-6 cm. The substrate layer 1 is present on a layer 4, for example a layer of earth, rubble, road-metal, etc. Although the layer 4 is shown to be a single layer in figure 2, it should be understood that the layer 4 may comprise one or more further layers, such as a layer having the above-described honeycomb structure or a layer comprising a matrix of plastic foil, in which foil air-filled chambers are present. If desired, the gel layer 3 may be provided with a protective layer (not shown) at the upper side thereof.
Figure 3 shows a special embodiment of the present invention, in which in fact the same substructure as shown in figure 1 is used, with this difference that the artificial grass fibres 2 are now more or less embedded in the substructure 7 by means of an infill 15 composed of sand and/or rubber granules, which infill lies on top of the substrate layer 1.

Claims

An artificial lawn whose substructure comprises a substrate layer (1) of artificial grass fibres (2) and one or more layers (3, 4) present under said substrate layer (1), wherein said artificial grass fibres extend in a direction away from said one or more layers (3, 4), wherein at least one of the layers (3, 4) present under the substrate layer (1) is a uniform gel layer (3) extending over substantially the entire dimension of the substrate layer (1), characterised in that said gel layer (3) is made up of a polyurethane-based gel having a homogeneous structure not comprising any separate, gel-containing compartments, wherein the thickness of the gel layer (3) ranges from 2-10mm.
An artificial lawn according to claim 1, characterised in that the gel layer (3) directly abuts against the substrate layer (1).
An artificial lawn according to any one or more of the preceding claims, characterised in that the energy restitution, determined over the entire substructure, ranges from 20-40, measured according to EN 15330, 2007.
An artificial lawn according to any one or more of the preceding claims, characterised in that the shock absorption, measured over the entire substrate, has a value of at least 20 %, measured according to EN 15330, 2007.
An artificial lawn according to any one or more of the preceding claims, characterised in that the density of the gel layer (3) ranges from 250-550 kg/m³.
An artificial lawn according to any one or more of the preceding claims, characterised in that the gel layer (3) comprises a polyurethane gel having a Shore 00 hardness of 0-50.
An artificial lawn according to any one or more of the preceding claims, characterised in that a loose infill is present between the artificial grass fibres (2) in the substrate layer (1).
An artificial lawn according to claim 7, characterised in that said infill is composed of the group consisting of sand, rubber and gel, or a combination thereof.
An artificial lawn according to any one or more of the preceding claims, characterised in that at least one of the layers (3, 4) present under the substrate layer (1) is composed of a material selected from the group consisting of asphalt, lava, fly ash, sand, rubble, clay granules, foamed concrete and road-metal, or a combination thereof.
An artificial lawn according to any one or more of the preceding claims, characterised in that the substrate (1) layer comprises natural fibres in addition to artificial grass fibres (2).