EP2121198B1 - Method for printing directly onto boards of wood-based material - Google Patents

Abstract

An assembly applies an outer coating to laminar floor panels of chipboard, medium- or high-density fiberboard. The panels (6) are fed by a belt (3) conveyer (11, 12) under a surface drying and hardening station (7). The assembly further incorporates a trough (5) for an acrylic semi-liquid surface coating agent. The board makes contact with the agent prior to exposure to an ultraviolet or electron beam drier. The assembly applies a surface structure to the coating by a belt (3) fed from a reel (1). Further claimed is a commensurate process.

Description

1. Field of the invention

The invention relates to a method for the coating of boards, in particular of wood-based panels for the production of floor panels, with a flowable coating material.

2. Background

From the prior art, a number of wood-based panels for the production of floor panels is known. Solid wood panels have an aesthetically pleasing surface but are very expensive. For this reason, veneer panels have been developed which have a base plate of a relatively inexpensive wood material, such as a low-cost wood species, to which a thin veneer layer of a higher quality wood species is applied. However, veneer sheets are still relatively expensive, so many consumers prefer laminate panels. Laminate panels essentially consist of an approx. 6 to 8 mm thick base plate made of MDF or HDF material, to which a decor paper layer is glued. The decor paper layer is impregnated with a resin and is usually further provided with abrasion-resistant particles. When creating the laminate panels, the application of pressure and heat hardens the resin and creates an extremely abrasion-resistant and decorative surface. Recently, new methods have been developed to print wood-based panels, such as MDF or HDF, directly with a plastic material, ie without the use of decorative paper. For this purpose, the MDF board, for example, is sanded off and primed. In a second step, a colored decor is printed on this primer, for example a wood decor. Thereafter, a plurality of very thin material layers are applied, wherein the individual material layers each cured before applying the next layer. The material layers are, for example, a plurality of, essentially transparent lacquer layers of a hardenable plastic. The resulting overall layer thus has a layered structure. Between the individual layers arise interfaces in which no good networking takes place. The individual layers usually have a thickness of 10 to 15 .mu.m and usually 5 to 7 layers are applied one above the other, resulting in a total thickness of the thin-layer system or layer stack of about 50-105 .mu.m.

As the name already refers to wood-based panel, this includes all wood-based materials in the broadest sense, ie panels that are made of wood, or that are made using wood materials. These include, but are not limited to, OSB panels, MDF or HDF, chipboard, solid and solid wood, veneered and prefinished parquet and others. In particular, this invention relates to improved wood-based panels for use as a floor covering or wall or ceiling covering.

From the publication DE 20 2004 018 710 U1 is a device for the coating of plates in the run out. Several plates are arranged on a conveyor belt, which are fed one after the other, inter alia coating stations. Such a coating station comprises an applicator roll, with which a lacquer is applied to a plate. This is followed by a post-processing device, with which the paint is cured, for example with UV radiation. The applicator roll may include a textured surface to pattern lacquer on the surface of a plate.

From the DE 20 2004 018 710 U1 It is also known to apply lacquer by a jet-printing technique, which is especially widespread in ink-jet printers, structured on a surface of a plate. This in turn is followed by a post-processing device with which the coating can be cured.

From the publication DE 20 2004 018 710 U1 Furthermore, a coating of workpieces such as plates, which come with a primer layer and a Priming layer is provided. On top of this there is a printed layer, which represents a decoration, above the decoration a lacquer layer is arranged. It can be used a so-called filled paint. These are paints which contain extremely fine solid particles such as corundum with diameters in the nanometer range.

From the DE 103 58 190 AI is a method for controlling printing presses out. With the device known therefrom furniture panels are printed. From the EP 0326919A2 is a method according to the preamble of claim 1 or 2, and a device for producing fast-curing coatings on carrier bodies previously known. The coatings consist for example of liquid plastics or synthetic resins to be cured by a brief thermal shock to a film.

It is the object of the invention to provide a new method with which a fast and cost-effective structured coating of plates, in particular for the production of floor panels, in good quality is possible.

These and other objects, which will become apparent from the following description, are achieved by the present invention.

3. Detailed description of the invention

The above object is achieved by a method according to claim 1 and an alternative method according to claim 2.

To achieve the object, a device may be used which comprises transport means for the transport of plates. The device also comprises a supply device with which coating material can be brought onto the plate surface. Subsequent to the feeding device, means for drying and / or curing the coating material are provided above the plate. In contrast to the above-mentioned prior art DE 20 2004 018 710 U1 the device comprises means to be able to pass a material web between the transport means for the transport of plates and the means for drying and / or curing.

If a material web with a structured surface is used, then the surface of the coating material can according to the invention be provided with a structure without having to exert high pressure. Since the coating material is dried and / or cured in this state, it is thus possible to coat a plate with a structured surface, without this being the case in the publication DE 20 2004 018 710 U1 known prior art either have to use a press or a complex printing unit. Also, a multi-step coating can thus be uniformly dried and / or cured in one operation. Above all, it is possible that a chemical network extends through the entire structure of the layer, resulting in a particularly stable coating.

If a material web with a smooth surface is used, so drying and / or curing under exclusion of air is possible. Drying and / or curing under exclusion of air is frequently desired, for example in order to achieve particularly high crosslinking in the case of curing of a varnish with UV light, ie a particularly high conversion of double bonds within the varnish. In the case of curing with electron beams, an air seal is usually required.

The invention relates to a novel process for coating a wood-based panel, in particular a particleboard, MDF or HDF board, with a flowable plastic material. In particular, the method relates to the production of panels, such as the manufacture of floor panels. In this method, a thick layer of at least 30 .mu.m of a plastic material is applied to the wood-based panel in a single step. The plastic material is preferably transparent at least after drying or curing. The layer is preferably applied in a single operation in a thickness of 30 to 150 microns, more preferably in a thickness of 80 to 110 microns and most preferably in a thickness applied by about 95 microns. In a further step, the layer of plastic material is cured. The use of a single thick layer instead of a series of many thin layers has a number of advantages. On the one hand, larger abrasion-resistant particles, such as, for example, larger corundum particles, can be provided than is possible with a thin-layer system. In the thin-film systems in which the individual thin layers only have a thickness of 10 to 15 .mu.m, and which are cured one after the other, in fact only relatively small particles can be used, since the particles are preferably incorporated as far as possible in the layers should be.

The flowable plastic material is preferably an acrylate system. By an acrylate system is meant, for example, a polymerizable mixture of double bond-containing mono-, di- and polyfunctional acrylic acid-based compounds. Typical representatives are for example Dipropylenglycoldiacrylat, 1,6-Hexandioldiacrylat, polyurethane acrylic acid ester, polyester acrylic acid ester as they are available in the production program of the company BASF under the trade name Laromer ™ types on the market.

The wood-based panel is preferably provided with a colored decorative print prior to coating with the flowable plastic material, e.g. with a wood decor. The plastic material is applied via the decor pressure and is preferably as transparent as possible. The process can be carried out, for example, as follows:

First, the carrier plate, such as an MDF plate, is honed and aligned or calibrated. Thereafter, a primer is applied and preferably applied a primer. Subsequently, the decoration is printed on the primer or the primer. In a further step, a further primer is applied, which is preferably a suitable primer for the following layer of plastic material. This primer is preferably applied in an amount of up to 10 g / m ² , more preferably of about 5 g / m ² . For example, a single thick layer of an acrylate system is applied to the primer by, for example, roller application. This is preferably done in an amount of up to 100 g / m ² , more preferably of about 65 g / m ² . On the not yet hardened Acrylate system are then preferably scattered corundum particles and depending on the required abrasion class up to 70 g / m ² , preferably 45 g / m ² . Over this layer is then preferably a Toplackauftrag a patterning film with preferably 2 - 100 g / m ² , more preferably 30 g / m ² . Finally, all layers are cured by UV radiation in a single operation. The cured acrylate system is preferably as transparent as possible, so that the underlying decorative pressure is visible.

The curing of the plastic material is advantageously carried out via a polymerization of the plastic material and not via a polycondensation. Accordingly, the plastic material is preferably a polymerizable acrylate system. Particularly preferred is the plastic material, such as the polymerizable acrylate system, a UV-curable plastic. The UV radiation serves to start the polymerization. Since the polymerization can be stopped at any time, it is thus possible in the single thick layer, e.g. May be 95 microns, a Vernetzungsgradienten and thus produce a cure gradients. The curing gradient is generated over a single, over the entire layer thickness occurring polymerization with the highest possible conversion. This is in contrast to painting with many thin films, which are applied layer by layer and then "gelled" by radiation, i. it is prematurely aborted the reaction. Thus, over the entire cross-section of all layers, there is no continuous polymer formation but boundary layers.

In an advantageous development of the process, several layers are applied wet-on-wet (for example primer, acrylate (roll application), corundum, topcoat application) and polymerized in a single step, preferably by UV excitation. The acrylate layer is cured according to the invention in a single thick layer. The individual layers differ in their function and thus also in the chemical structure: The primer has the task of producing good adhesion between the printing and the plastic layer. The middle layer is flexibly adjusted to reduce internal stresses and to avoid embrittlement and to absorb impact energy when walking when the coated board is used as a floor panel, for example. The Toplackschicht however, it is modified to lead to high hardness and scratch resistance. Since the wet-to-wet application causes intermixing of the layers, there are no boundary layers but actually a hardness gradient from top to bottom. Chemically summarized: The polymerization is carried out so that a nearly complete double bond conversion over the entire layer is achieved. The primer is preferably designed so that better adhesion is achieved by greater functionalization of the acrylate mixture. In particular, the middle layer has chain growth and only minor cross-linking. The Toplackschicht preferably contains a highly crosslinkable acrylate system.

In order to increase the abrasion resistance of the layer, abrasion-resistant particles, in particular corundum particles, are preferably introduced into the layer. Since the layer is very thick, it is possible to incorporate relatively thick particles which have better abrasion properties than smaller particles. Depending on the layer thickness used, eg corundum particles in a range from DF 220 to DF 280 according to the FEPA specification (Federation of European Producers of Abrasives) are used. These then have an average grain size D ₅₀ of 36.5 to 63.0 microns. Particular preference is given to using particles in the range from DF 240 to DF 280, ie having particle sizes D ₅₀ of 44.5 to 36.5 μm. In the case of the above-mentioned layer systems with several thin individual layers (so-called thin-layer systems), which are applied to one another, relatively small particles (such as corundum particles) must be used, since otherwise they would protrude too far from the individual layers. The particle size is usually in the range of DF 320 to DF 500 according to the FEPA specification. That is, the previously usable grain sizes of the abrasion-resistant particles were limited to an average grain size D ₅₀ of 29.2 to 12.8 microns. These relatively small particles lead to lower abrasion values with the same additional amount, ie with the same abrasion class, a larger amount by weight must be used with finer particles than with larger particles. In addition, finer particles lead to a poorer transparency of the surface and graying phenomena.

The introduction of the particles into the layer can be carried out after application of the layer in which the particles are sprinkled, for example, on the not yet cured layer. After the particles have sunk or pressed into the layer, the material is cured so that the particles are firmly entrapped in the layer. Another possibility is to introduce the particles before the application of the layer in the flowable plastic material, for example in the form of a dispersion.

According to the first alternative of the invention, prior to the curing step, ie after the layer has been applied to the plate, a material web having a structured surface, practically without pressure, is applied to the layer of plastic material. In this way, a structure is embossed in the layer of plastic material. Since the layer is still liquid at this time, virtually no pressure needs to be expended. In a next step, the layer of plastic material is dried and / or cured, whereby the introduced into the layer of plastic material structure is fixed. Thereafter, in a further step, the material web with structured surface can be removed again. In the second alternative of the invention, a pattern roll is used to emboss a structure in the layer of plastic material. This in turn happens after the application of the plastic material to the plate but before the curing of the plastic material. If possible directly after the structure has been impressed, in a next step the layer of plastic material is dried and / or hardened, whereby the structure introduced into the layer of plastic material is fixed. Due to the thickness of the layer according to the invention, structure depths of 0 to 80 μm are possible. Structural depths of from 20 to 80 μm and particularly preferably up to about 35 μm are particularly preferred. In the prior art, in which a layer system of individual thin films was used, it was not possible to produce structure depths of more than 5 to 10 microns. These small structure depths are not sufficient for many purposes. For example, to realize a realistic real wood imitation, deeper structures must be imprinted into the layer. With the very deep structures according to the present method, therefore, patterns and structures can be incorporated into the layer that are aesthetically pleasing and not previously possible were. A texture depth of 35 microns is clearly felt and visible to the naked eye and is particularly suitable to imitate the structure of real wood floors.

In an alternative embodiment, not according to the invention, a material web with a smooth surface is applied to the layer of plastic material without exerting much pressure. In this way it is prevented that air gets to the plastic material. In a next step, the layer of plastic material is dried and / or cured in the absence of air. In a further step, the material web with a smooth surface is removed again.

The material webs used, whether with a smooth or structured surface, are preferably permeable to UV light. If a UV-curable plastic is used, it is thus possible to cure the plastic, although it is covered by the material web.

The presented method offers particular advantages in the coating of wood-based panels made of real wood, such as veneer or parquet, for example, engineered parquet. So far, it has been a disadvantage of such real wood panels that the surfaces are relatively sensitive. With the method according to the invention, real wood floors can now also be provided with a coating which has high abrasion values and which nevertheless has an aesthetically pleasing surface due to the incorporated three-dimensional structure. If real wood floors were previously provided with an abrasion-resistant coating in order to increase the durability of, for example, floors made of this material, the natural three-dimensional structure of the real wood has proven to be disadvantageous. Namely, the paint or coating applied in the wet state tends to flow into the recesses of the natural structure, so that the coating of the protruding portions between the recesses is insufficient. However, by applying a thicker layer to protect the protruding areas between the recesses by means of the coating, the natural three-dimensional structure of the real wood is completely filled up, resulting in an undesirably flat surface. Namely, such a flat surface impairs the optical effect caused by the three-dimensional Structures to be achieved; that is, to create or emphasize the impression of a real wood material. However, the problem of filling the natural structure of the real wood occurs even at very low thicknesses of the coating. The prior art has attempted to avoid this problem by machine-milling deeper structures into the real wood surface. However, this additional process step makes the products more expensive and, moreover, makes the coating even more difficult due to the above-described problem that the liquid coating material collects in the depressions. Although these problems have been known for a long time, it has not yet been possible to solve them satisfactorily. With the present invention, now for the first time offers the opportunity to provide real wood panels with an abrasion-resistant coating, which still preserves convincingly the desired aesthetic properties of real wood panels due to a suitably embossed three-dimensional structure. In particular, it is possible for the first time with the present invention to produce real wood floors made of solid and solid wood, such as wood planks, or wood veneer and engineered parquet with very high abrasion values, which nevertheless have a three-dimensional surface structure, which gives the impression of a real wood material.

In one embodiment, the supply device comprises a coating material catcher disposed adjacent to the transport means for transporting the plates. The collecting device further adjoins a roller for transporting the material web. The collecting device is designed so that liquid, located in the catcher coating material flows to the roller. It is thus achieved that, given a sufficiently large filling of the collecting device, liquid coating material can completely coat a material web with a liquid film when a material web is transported over the roller. Overall, it can be achieved with sufficient supply of liquid coating material that the liquid coating material completely fills the space between the surface of a plate and the material web located above it. It then gets very reliable no air in the area. Curing can be carried out so particularly reliably under exclusion of air.

Also, in this embodiment, it is possible to apply relatively thick paint layers having a total thickness of, for example, 80 to 100 μm in thickness and to uniformly dry and cure. This in turn makes it possible to embed relatively thick abrasion-resistant particles such as corundum with a diameter of up to 100 μm within the paint. Since the abrasion resistance increases with the diameter of the abrasion-resistant particles, a relatively high abrasion resistance can be achieved. Nevertheless, as the diameter of the abrasion-resistant particles increases, the amount of abrasive material can also be reduced. This achieves both an improvement in abrasion values and an improvement in the transparency of the abrasion-resistant coating.

Particle grain sizes of DF 220 to DF 280 FEPA are particularly preferred. The thickness of the layer is preferably 30 to 150 μm, more preferably 80 to 110 μm.

In one embodiment of the invention, the means for transporting plates comprise a circulating conveyor belt onto which the plates are deposited for transport.

In a preferred embodiment of the method, after the application of the layer of plastic material, but before the curing or drying of the same, foreign materials are introduced into the layer, for example, interspersed, for example, to achieve an aesthetically pleasing effect. The foreign materials are preferably natural materials such as cork or hemp, but also plastics and metal particles are suitable. The foreign materials can be introduced in such a way that they partially protrude from the layer in relief, or else that they have completely sunk into the layer. The layer is preferably transparent, so that the foreign bodies therein are visible. For example, leaves or tree needles can be inserted into the liquid material layer, which are preferably completely sunk in and surrounded by the layer. Subsequently, the transparent layer is cured. Since, for example, natural materials are completely surrounded by the layer, which can be an acrylic resin, for example, and thus are protected from air and weathering are protected, there is no decomposition of natural products. Such a treated plate, with a transparent hard plastic layer in which foreign materials are introduced, can thus have an aesthetically very appealing effect. Other conceivable materials are, for example, leaves, twigs, branches or wool. The introduction of foreign materials is made possible by the relatively large thickness of the layer.

In one embodiment of the invention, the web of material is unrolled from a roll, guided over further rolls parallel to the surface of sheets which are being transported, and then rolled up again by a roll. In contrast to the aforementioned prior art, an exchange of the material web is sufficient if a surface structure is to be changed or if a structure on the material web has damage, for example due to signs of wear. By using a material web, a consistent quality of a generated surface structure can also be ensured, since, in contrast to a roll with a structured surface, with the unrolling of the material web, the quality of the surface of the material web which produces the structure is not changed. In addition, the structure in the surface of the coating is generated virtually without pressure, so that the surface of the material web is subject to practically no signs of wear for this reason.

In one embodiment of the invention, the rollers for the transport of a material web are arranged so that they are similar to the catcher in cross section a funnel. The supply of coating material to the surface of a plate then finally takes place via a gap. This ensures the proper supply of coating material between the web and surface of the plate to be coated further improved.

In one embodiment, the width of the aforementioned gap can be changed. This serves to control the amount of coating material which is fed to the surface of a plate. Also, the gap in one embodiment be closed, so as to be able to control the time of delivery. 4. Description of Preferred Embodiments Hereinafter, the invention will be described with reference to FIGS FIG. 1 explained in more detail.

FIG. 1 shows a device with which a carrier material 6, such as a chip, MDF or HDF plate can be coated in a continuous process. The coating materials used are preferably UV- or electron beam-crosslinkable, flowable systems of suitable viscosity.

On the input side of the coating system, a carrier material 6 is supplied and coated with a flowable material 8. The coating takes place via a collecting device 5, which adjoins a roller 4. A web-shaped material, namely a UV-transparent and / or electron-radiation-permeable and radiation-resistant film 3, is guided over the roller 4. The film has a smooth, the coating material 8 facing surface when the coating 8 is to have a smooth surface. The corresponding surface of the film 3 is structured when the coating 8 according to the invention should have a structured surface.

The web-shaped material or the film 3 is unrolled from a supply roll or supply roll 1 and finally rolled up again on a roll 2. Between the roller 1 and the roller 4 there are along the transport path for the sheet-like material 3, three further rollers with a relatively small diameter, which serve to guide the sheet-like material. The feed throat 13 of small diameter located adjacent to the roll 4, together with the roll 4, causes the sheet material together with the trap 5 to form a cross-sectionally funnel-shaped inlet for coating material 8. The coating material 8, for example a lacquer, is suitably brought between the carrier material 6 and the sheet-like material 3 via this funnel shape.

The funnel-shaped inlet opens into a gap. The gap width can be changed to control the supply of coating material.

Between the roller 4 and the roller 2 there are four further guide rollers with a relatively small diameter, which serve to guide the web-like material from the roller 4 to the roller 2. The first guide roller 10 - seen from the roller 4 in the transport direction of the sheet material - causes, together with the roller 4, that the web-like material is guided parallel to the surface of the carrier material 6.

Between the roller 4 and the roller 10 there are above the film 3 means 7, with which the underlying coating material can be dried and / or cured. These are above all devices for curing with UV light or electron beams.

With the device, during the coating process, a web-shaped smooth or structured material 3 is aligned at the same time from the supply roll 1 both in the longitudinal direction and in the transverse direction and applied synchronously to the carrier material 6 by means of the roller 4 and the catcher 5 on the still liquid coating material. The aim of the orientation of the web-shaped material is to synchronize certain points of the carrier material 6 with certain points of the web-like material fitting one above the other. For this purpose, in one embodiment of the invention, the speed of a carrier material or a plate 6 is measured with measuring devices. Preferably, optical measuring devices are used to determine the speed of the carrier material. For example, by means of electronic or magnetic sensors, the rotational speed of at least one roller or roller is involved, which is involved in the transport of the sheet-like material. The thus obtained information about the transport speed of each plate 6 and transport speed of the sheet material are used for the control. The two speeds are thus controlled so that a plate is brought together defined with the web-like material, so as to be able to structure a surface targeted.

In one embodiment of the invention, the sheet-like material, for example, optical marks, which are detected with optical sensors. The transport of the sheet material and / or the transport of the plates 6 are controlled so that a plate is coated in dependence on such an optical marking and the coating is structured in dependence on these optical markings.

The carrier material with the liquid coating material and the overlying sheet-like material then passes through the curing station 7. In this, the liquid coating material 8 is crosslinked and goes into a solid state. During the curing process, the surface structure of the web-like material is fixed and imaged in the hardened layer.

On the output side of the coating system, the sheet-like material is removed from the cured solid coating material and wound up again into a roll.

It is still in an in FIG. 2 shown embodiment provided that a plurality of supply rolls 1 and take-up rolls 2 are present for the web-like material. The supply rolls and the Aurwickelrollen can be endlessly connected during production by a device without stop.

The connection is made for reasons of practicality, preferably at speeds up to 120 m / min. The respective at rest film receiving station is charged with a roll of web-like material and prepared the automatic connection by a double-sided adhesive tape is glued to the web beginning. The beginning of the sheet material is inserted into a gap, which serves to connect. Through this gap at the same time the web-like material is guided, which is currently being unrolled. The triggering of the connection is done automatically by electronically detecting the running meters of the roll, from which web-shaped material is unrolled, or sensory Detecting the associated end of a web-shaped material. Before joining, the running web-like material is stored in a dancer device operating as a web store. The driven roller is reduced to a speed of about 15 m / min. The missing length of the web-like material to the line speed pulls out of the dancer. Accelerate after the connection! the corresponding film roll again up to the maximum speed of, for example, 120 m / min until the dancer roller has returned to its working position.

The automatic connection device comprises at least two unwind stations with flap bearings and pneumatic tension shafts. The drive of the bends is made by a servo motor, means are available to automatically adjust cars with the films or web-like materials. The actual connecting device comprises four pneumatically operated mangle rollers. There are also two cutter blades for cutting the web material after bonding. An automatic braking force regulation of the unwinding rolls is available. This includes dancer rollers, pneumatic proportional linear cylinders with guide and guide rollers and an automatic crack control.

The carrier material or a plate 6 is first passed through the two superimposed, rotating rollers 4 and 11 passed through and transported. From here, the carrier material 6 reaches a conveyor belt 12, which further transports the carrier material. The web-shaped material or the film 3 and the carrier material 6 are transported at the same speed.

The distance between the two rollers 4 and 11 can be changed in order to vary the thickness of the coating can. In one embodiment, the height of the guide roller 10 can be changed in order to influence the thickness of the coating can.

Claims (11)

1. Method for coating a board of wooden material, in particular a real wood board, a veneer board or a parquet board, with a flowable plastic material, whereby the method comprises the following steps:

   - applying the plastic material as a single layer onto the board of wooden material,

   - arranging a web with a structured surface onto the plastic material to provide the layer of plastic material with a structure,

   - drying and/or curing the layer of plastic material, whereby the structure introduced into the layer of plastic material is fixed, and

   - removing the web with a structured surface, whereby the plastic material increases the abrasion resistance of the board of wooden material, characterized in that the layer is applied in a single process step in a thickness of at least 30 µm.
2. Method for coating a board of wooden material, in particular a veneer board or a parquet board with a flowable plastic material, whereby the method comprises the following steps:

   - applying the plastic material as a single layer onto the board of wooden material,

   - embossing a structure into the layer of plastic material by means of a structured roller, before the layer of plastic material is cured to provide the layer of plastic material with a structure,

   - drying and/or curing the layer of plastic material, whereby the structure introduced into the layer of plastic material is fixed, whereby the plastic material increases the abrasion resistance of the board of wooden material, characterized in that the layer is applied in a single process step in a thickness of 30 µm.
3. Method according to claim 1 or 2, characterized in that the structure has a depth of up to 80 µm and preferably a depth of 35 um or more.
4. Method according to claim 1, characterized in that the web is transparent for UV light.
5. Method according to one of claims 1 to 4, characterized in that the plastic material is a plastic, which is curable by means of UV radiation.
6. Method according to one of claims 1 to 5, characterized in that the layer is applied in a single process step in a thickness of 30 to 150 µm and preferably of 80 to 110 µm and particularly preferred in a thickness of approximately 35 µm.
7. Method according to one of the claims 1 to 6, characterized in that after application of the layer of plastic material and prior to the provision of the structure, abrasion resistant particles, in particular particles with a grain size D₅₀ of 36,5 to 63 µm and preferably D₅₀ of 36,4 to 44,5 µm are embedded into the layer of plastic material, to increase the abrasion resistance of the layer.
8. Method according to one of claims 1 to 7, characterized in that prior to the application of the layer of plastic material, abrasion resistant particles, in particular corundum particles, with a grain size D₅₀ of 36,5 to 63 µm and preferably D₅₀ of 36,4 to 44,5 µm are embedded into the layer of plastic material to increase the abrasion resistance of the layer.
9. Method according to one of claims 1 to 8, characterized in that the plastic material is a polymerizable acrylate system.
10. Method according to one of claims 1 to 9, characterized in that the curing of the plastic material is affected by means of a polymerization of the plastic material.
11. Method according to one of claims 1 to io, characterized in that after the application of the layer of plastic material, other materials as e.g. straw, tree needles, metal cuttings and similar are introduced into the layer, to provide an esthetical effect.

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