METHOD AND DEVICE FOR MANUFACTURING ARTIFICIAL TURF

The present invention relates to a method for manufacturing artificial turf as described in the preamble of claim 1, and a device for manufacturing artificial turf as described in the preamble of claim 12. Such a method and device are generally known.

Artificial grass forms an important alternative to natural grass. It is less susceptible to weather influences and therefore also requires less frequent maintenance.

Artificial turf is usually manufactured by means of the techniques taken from the carpet industry, such as tufting or weaving. Synthetic fibres are here inserted through a carrier, thereby creating loops. These loops can then be cut, whereby blades of grass are created. It is important that the loops or blades remain attached to the carrier in order to prevent open spaces in the grass cover.

The process for manufacturing artificial turf consists of two separate steps, forming the loops or blades and fixing thereof. Fixing has heretofore taken place in a long latex-applying or coating line in a separate shop floor or space adapted for this purpose. It is therefore usual to first wind the carrier with the blades or loops onto a roll after the tufting or weaving, and to then take this roll to the latex-applying line. The roll is there unwound, wherein the carrier is coated with latex. The latex is then allowed to harden, after which the artificial turf is wound onto the rolls again.

Other techniques for fixing the synthetic fibres to the carrier are also known. The synthetic fibres can for instance be fused to the carrier. Pressure rollers are used here which transfer heat to the carrier.

One of the drawbacks of the present manufacturing techniques is that they deform the artificial turf or artificial turf fibres . The deformation may occur because during the process, in particular during the fixing, use is made of pressure rollers. The angle at which the synthetic fibre leaves the carrier hereby becomes different from the desired angle, this being substantially perpendicular to the carrier. Synthetic fibres can

further become detached from the carrier during the process. This is particularly the case when the artificial turf is wound onto a roll after the tufting.

Another drawback of the present art are the economic consequences of maintaining and operating a separate fixing device. Because the drying time of latex is considerable, a very long drying line in the order of hundreds of metres or more is necessary. This thus requires a large conditioned space. The latex-applying process also requires a continuous feed of the carrier. In order to prevent possible disruptions in the tufting or weaving machine influencing the fixing process, the carrier is wound onto a roll after the tufting or weaving. Deformation of the artificial turf can hereby occur once again. In order to prevent interruption of the fixing process, large quantities of artificial turf wound onto rolls will moreover have to be stored as buffer, which takes up space and entails cost.

It is an object of the present invention to provide a method for manufacturing artificial turf, wherein the above stated drawbacks do not occur, or at least do so to lesser extent. According to a first aspect of the present invention, this object can be achieved by means of a method comprising of:

- providing a carrier and synthetic fibres,

- connecting the synthetic fibres to the carrier by means of tufting or weaving, wherein the synthetic fibres form blades or loops on the upper side of the carrier, and

- fixing the synthetic fibres to the carrier, characterized in that the fixing takes place at a speed which is substantially at least equal to the speed of the tufting or weaving. This creates the possibility of adapting the fixing and the tufting or weaving to each other and combining thereof in optimal manner.

An advantageous method can further be obtained if during the fixing the carrier is advanced at a speed substantially corresponding to the speed the carrier has during connecting of the synthetic fibres to the carrier. It hereby becomes possible to perform the fixing and tufting or weaving process continuously. The intermediate step, in which the

carrier is wound onto a roll, is thus eliminated and the deformation which thereby occurs is thus prevented.

It is advantageous to fix the synthetic fibres immediately after the tufting or weaving. In order to reduce the chance of possible deformation, it is further advantageous to carry out the fixing without pressure.

The fixing preferably takes place by means of arranging and allowing fixing means to harden. Examples hereof are the use of glue or hot-melt techniques. Techniques such as ultrasonic welding or infrared fusion can also be used.

In order to improve or accelerate the fixing an auxiliary layer can be arranged on the underside of the carrier. This layer can for instance improve the adhesion of the glue or hot melt to the carrier. Another application can for instance be that this layer heats quickly during the ultrasonic welding or the infrared irradiation. Although the layer is usually arranged before the fixing, applications are possible in which the layer is arranged after the actual fixing, for instance in order to reduce the hardening time of a glue. In a further preferred method a stabilizing layer is arranged on the underside of the carrier after the fixing. This layer can improve the stiffness or strength of the artificial turf.

According to another aspect of the invention, there is provided a device for manufacturing artificial turf, comprising:

- a tufting or weaving machine with a first guiding system, which machine connects synthetic fibres to a carrier, wherein loops or blades are created on the upper side of the carrier, and

- a fixing station with a second guiding system, which station arranges fixing means on the underside of the carrier, characterized in that the tufting or weaving machine and the fixing station are connected in series and the first and second guiding systems have substantially the same guiding speed.

In a preferred embodiment the first and second guiding systems form a continuous guiding system. This guiding system

can comprise a number of rollers which together define a path for the carrier and are driven at the same speed.

The fixing station preferably comprises an ultrasonic welding station, a hot melt station, a glueing station or a 5 station for infrared radiation.

By positioning the carrier substantially in vertical direction during the fixing or tufting a great space-saving can be obtained compared to the situation in which the carrier moves substantially in the horizontal plane.

10. The device can also comprise a station which arranges an auxiliary layer on the underside of the carrier. Such a layer can be arranged by means of known techniques such as laminating or glueing. This station can be incorporated in the overall device both before and after the actual fixing station. The

15 device can also comprise a station which arranges a stabilizing layer on the underside of the carrier. It is possible for both the stabilizing layer and the auxiliary layer to be arranged in a liquid form on the carrier, for instance by means of a spraying technique .

20 According to a further aspect of the invention, there is provided an artificial turf, comprising a carrier and synthetic fibres forming blades which are connected to the carrier by means of fixing means, characterized in that the hardening or drying time of the fixing means is a maximum of two

25 minutes.

In a preferred embodiment the artificial turf is characterized in that the fixing means used are polyurethanes, acrylates, thermoplastic elastomers or polymers belonging to the same product group as the material from which the fibres are

30 constructed, in order to thus achieve full recyclability. The artificial turf cari also comprise a stabilizing layer and/or an auxiliary layer which shortens the hardening or drying time of the used fixing means or improves the adhesive properties of these means .

35 The properties of the synthetic fibres and the carrier can be adapted to the production method. In an embodiment separate fibres are added to the blade-forming synthetic fibres, these separate fibres having the property that they fuse more

easily than the synthetic fibres. The materials used can also be chosen such that the whole is environmentallv-friendly or recyclable .

In the preferred embodiment the blade-forming synthetic fibres comprise substances from the group consisting of polyolefins (such as polyethylene) , polyamides or thermoplastic elastomers. In another preferred embodiment the carrier comprises substances from the group consisting of polyolefins or thermoplastic elastomers. The invention will be further described with reference to figures 1-5, in which: figure 1 shows a schematic view of a preferred embodiment of the device; figures 2A-2C show different embodiments of the fixing station; figure 3 shows a schematic view of an embodiment of a station which arranges an auxiliary or stabilizing layer,- figure 4 shows a cross-section of a preferred embodiment of the artificial turf according to the present invention; and figure 5 shows the same cross-section, wherein extra layers are incorporated in the artificial turf .

Figure 1 shows a schematic view of a preferred embodiment of a device for manufacturing artificial turf according to the present invention. Carrier 1 is here fed to a tufting station 2 from a roll 16. Synthetic fibres 3 are likewise fed from rolls 17-17' '. During tufting an assembly of needles 4 presses synthetic fibres 3 through carrier 1. Loops 5 are thus formed which in the shown embodiment are cut open by a knife 6 at a later stage, thereby forming blades 21. After tufting the carrier 1 is transported further in the direction of a fixing station 7. This transport takes place by means of a guiding system, which here takes the form of a number of rollers 18, 19, 20, which are driven at the same speed by one or more motors (not shown here) . The shown embodiment can also comprise a station 8, which arranges an auxiliary layer, and a station 9 which arranges a stabilizing layer.

Figure 2A shows a detail view of an embodiment of fixing station 8, wherein a glueing technique is applied for the purpose of fixing synthetic blades 21 to carrier 1. A glue spraying device 23 sprays glue 22 onto the rear side of carrier 1. The synthetic blades 21 protruding from the front side of carrier 1 are hereby fixed.

Figure 2B shows another embodiment of fixing station 8. In this embodiment a hot melt technique is used to fix synthetic blades 21 to carrier 1. A thermoplastic adhesive 25 is here sprayed onto carrier 1 by a spray device 24. Heating of thermoplastic adhesive 25 can take place in spray device 24 itself as well as by means of optional pressure rollers 26 and 26' which are heated.

Figure 2C shows an embodiment of fixing station 8 wherein synthetic blades 21 are connected to carrier 1 by fusing together thereof using infrared (I. R.) light 27. This light 27 comes from a light source 28 which locally heats synthetic blades 21 and carrier 1, whereby they fuse together.

Figure 3 shows an example of an embodiment of a station 8 or 9 which arranges a layer 10, being respectively an auxiliary or stabilizing layer. Layer 10 is arranged by means of pressure rollers 11 and 11' , wherein the side of layer 10 directed toward carrier 1 can be provided with binding means 29, for instance glue. Layer 10 can also be formed by making use of other techniques, for instance by spraying or spreading layer 10 onto the carrier in liquid form in a latex-applying line, or by laminating thereof (not shown) .

Figure 4 shows a cross-section of a preferred embodiment of artificial turf 12 according to the present invention. In this example the artificial turf 12 comprises a carrier 1, synthetic blades 21 and a glue 13 for connecting the synthetic blades 21 to carrier 1.

A further embodiment is shown in figure 5. In addition to the above stated components, the artificial turf 12 in this figure also comprises an auxiliary layer 14 and a stabilizing layer 15.

The foregoing description and the associated figures serve to illustrate the invention. It will be apparent that other

embodiments of the present invention are possible. The scope of the invention is therefore defined solely by the following claims .