EP4326481A1

EP4326481A1 - Method for producing a decorative panel having improved structuring

Info

Publication number: EP4326481A1
Application number: EP22723112.3A
Authority: EP
Inventors: Hans-Jürgen HANNIG; Felix HÜLLENKREMER; Paul Weyer
Original assignee: Akzenta Paneele and Profile GmbH
Current assignee: Akzenta Paneele and Profile GmbH
Priority date: 2021-04-19
Filing date: 2022-04-14
Publication date: 2024-02-28
Also published as: WO2022223470A1; CA3215910A1; EP4079446A1; KR20230169338A; BR112023019122A2; CN117177835A

Abstract

The present invention relates to a method for producing a decorative panel, comprising the following method steps: a) applying a decorative layer to a substrate, b) optionally applying an intermediate layer to the decorative layer, c) applying a cover layer to the decorative layer or the intermediate layer, and d) structuring at least one layer (28) to be structured, said layer (28) to be structured being selected from the decorative layer, the intermediate layer and the cover layer, characterised in that method step d) comprises the following method steps: d1) generating a laser beam (12); d2) dividing the laser beam (12) into a matrix (16) of a plurality of sub-beams; d3) guiding the matrix (16) of sub-beams into a modulator (24) for selective inactivation of individual sub-beams; d4) guiding the matrix (16) of sub-beams from the modulator (24) into an optical scanner (26), the matrix (16) of sub-beams downstream of the modulator (24) comprising all the sub-beams guided into the modulator (24) or a reduced number of sub-beams; and d5) guiding the matrix (16) of sub-beams from the scanner (26) onto the layer (28) to be structured; d6) the layer (28) to be structured being negatively structured under the action of the sub-beams in order to generate a three-dimensional structure (34).

Description

AKZENTA PANEELE + PROFILE GMBH Düsseldorf, April 14, 2022 Our reference: CD 43122 / UAM

AKZENTA PANELS + PROFILE GMBH Wemer-von-Siemens-Str. 18-20, 56759 Kaisersesch, Germany

Process for producing a decorative panel with improved structuring

The present invention relates to a method for manufacturing a decorative panel. The present invention relates in particular to a method by which high-precision structures can be introduced into a panel layer in a simple and adaptable manner with a high throughput by means of laser structuring.

In the course of the production of a decorative panel, it may be desirable to provide a layer of the corresponding layer structure with a structure. This can be realized in a conventional manner, for example, by the action of a press plate, in that this is pressed onto the layer to be structured, in particular under the effect of temperature and pressure.

However, it is also known to introduce structures into the layer to be structured by means of laser treatment.

DE 10 2005 046 264 A1 describes a method for producing a panel with a surface coating applied at least in sections, with the steps

- Application of an untreated porous layer

- Introduction of pores in the pore layer by means of laser processing.

This document further relates to a panel, the surface of which is provided at least in sections with a porous layer into which pores are introduced by means of laser processing. EP 3 685 979 A1 describes a method for producing floor panels, comprising the following method steps:

- production of a pressed plate provided with a relief,

- forming the aforesaid floorboards, the pressing plate being used at least to realize embossed portions in the upper surface of a board, from which floorboards are subsequently formed, the relief in the pressing plate being realized by means of a laser treatment, and the laser treatment being a material deposition process. However, the aforementioned prior art can still offer further potential for improvement, in particular with regard to the structuring of a decorative panel by means of a laser treatment.

The object of the present invention is therefore to at least partially overcome at least one disadvantage of the prior art. The object of the present invention is, in particular, to provide a solution by means of which laser structuring is possible with high resolution and high throughput as part of the production of a decorative panel. This object is achieved by a method with the features according to claim 1. Preferred embodiments of the invention are specified in the subclaims or in the description, with further features described or shown in the subclaims or in the description individually or in any combination invention unless the context clearly indicates the opposite.

A method for producing a decorative panel is described, having the method steps: a) applying a decorative layer to a carrier, b) optionally applying an intermediate layer to the decorative layer, c) applying a top layer to the decorative layer or the intermediate layer, and d) structuring at least one layer to be structured, the layer to be structured being selected from Group consisting of decorative layer, the intermediate layer and the top layer, where

Method step d) comprises the method steps: dl) generating a laser beam; d2) dividing the laser beam into a matrix of a plurality of partial beams; d3) directing the array of sub-beams into a modulator for selectively inactivating individual sub-beams; d4) guiding the matrix of partial beams from the modulator into an optical scanner, the matrix of partial beams after the modulator comprising all of the partial beams directed into the modulator or a number reduced thereto; and d5) guiding the matrix of partial beams from the scanner onto the layer to be structured; where d6) the layer to be structured is negatively structured under the action of the partial beams to produce a three-dimensional structure.

Such a method can have significant advantages over prior art solutions. The method is used to produce a decorative panel. For the purposes of the present invention, the term decorative panel is to be understood in particular as meaning wall, ceiling, door or floor panels which have a decoration applied to a carrier plate. Decorative panels are used in a variety of ways both in the field of interior design Rooms, as well as for the decorative cladding of buildings, for example used in trade fair construction. One of the most common areas of application for decorative panels is their use as floor coverings, to cover ceilings, walls or doors. The decorative panels often have a decoration and a surface structure which is intended to imitate a natural material. It can also be advantageous if the haptically perceptible structure is adapted to the decor, ie a so-called synchronous pore is present.

The method described here comprises the following method steps.

According to process step a), a decorative layer is applied to a carrier. A corresponding carrier can thus be provided first.

The carrier used is not limited per se. Basically, it can be preferred that the carrier is made of a plastic. The carrier can particularly preferably have a material comprising a plastic. Plastics that can be used in the production of corresponding panels or the carrier are, for example, thermoplastics such as polyvinyl chloride, polyolefins, for example polyethylene (PE), polypropylene (PP), polyamides (PA), polyurethanes (PU), polystyrene (PS) , acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyetheretherketone (PEEK) or mixtures or copolymers of these. The plastics can contain customary fillers, for example calcium carbonate (chalk), aluminum oxide, silica gel, quartz flour, wood flour, gypsum. They can also be colored in a known manner. The carrier can preferably contain talc as a filler, for example in an amount, based on the total material of the carrier, of >30% by weight to <70% by weight, in particular from >40% by weight to <60% by weight In addition, it can be provided that the carrier has a multilaminar structure, ie from a large number of films. However, within the meaning of the present invention, it is not excluded that the carrier is wood-based, for example consists of wood, ie is an HDF or MDF carrier. Furthermore, the carrier can be a so-called WPC carrier, for example, without departing from the scope of the invention.

The application of the decorative layer is also not limited in principle. In particular, however, the decor should imitate a decor template. A “decor template” can thus be understood in the sense of the present invention as such an original natural material or at least a surface of such that is to be imitated or imitated by the decor.

The decoration can be applied, for example, by the decoration being applied directly to the carrier, for example by a printing process, in particular a digital printing process. A suitable printing substrate can also be provided on the carrier. Alternatively, it is not excluded within the meaning of the present invention that the decoration is applied in such a way that, for example, a fiber layer that has already been printed, such as a paper layer, or also a film that has already been printed, such as polyethylene, polypropylene or polyvinyl chloride, for example, is applied to the carrier .

For the purposes of the invention, the term fiber materials is to be understood as meaning materials such as paper and nonwovens based on plant, animal, mineral or artificial fibers, as well as cardboard.

Furthermore, the fiber layer or the film can be printed on the carrier and thus serve as a printing substrate. Furthermore, according to method step b), an in particular transparent intermediate layer is optionally applied to the decorative layer. In principle, such an intermediate layer can also be selected. For example, the intermediate layer can serve as a protective layer together with the subsequent top layer. A further possibility is that the intermediate layer is a structure layer, that is to say it can be used in particular to introduce the structure. As a non-limiting example, the intermediate layer may be a film, such as a plastic film formed from, for example, polypropylene. With regard to a film made of polypropylene, it has been shown that, due to its physical and mechanical properties, it is very well suited for laser-based structuring, even with high throughput. In addition, there is the further advantage that comparatively few toxic vapors are produced during evaporation, for example in comparison to PVC. In principle, the intermediate layer can be made, for example, from an elastomer, a thermoplastic, an aminoplast or a lacquer. Examples of thermoplastics include polyvinyl chloride (PVC), polyolefins such as polyethylene (PE) or polypropylene (PP), polyethylene terephthalate, polyester, thermoplastic polyurethane (TPU), styrene or its derivatives (eg ASA, ABS). Examples of aminoplasts include urea and melamine formaldehyde resins or mixtures thereof. Examples of paints include acrylate-based paints, such as acrylate-based UV-curable paints and / or aqueous paint systems.

According to process step c), an in particular transparent cover layer is then applied to the intermediate layer or to the decorative layer. Such a layer to protect the applied decoration can be applied in particular as a wear or cover layer above the decorative layer or intermediate layer in a subsequent process step, which in particular protects the decorative layer from wear or Damage caused by dirt, moisture or mechanical influences such as abrasion protects. For example, it can be provided that the wear and/or cover layer is placed on the printed carrier as a pre-produced overlay layer, for example based on melamine, and is connected to it by the action of pressure and/or heat. Furthermore, it can be preferred that a radiation-curable composition, for example a radiation-curable lacquer, such as an acrylic lacquer, is also applied to form the wearing and/or top layer. It can be provided that the wearing layer has hard materials such as titanium nitride, titanium carbide, silicon nitride, silicon carbide, boron carbide, tungsten carbide, tantalum carbide, aluminum oxide (corundum), zirconium oxide or mixtures of these in order to increase the wear resistance of the layer. The application can be applied, for example, by means of rollers, such as rubber rollers, or by means of pouring devices.

Furthermore, the cover layer can first be partially cured and then a final coating with a urethane acrylate and final curing, for example with a gallium radiator, can be carried out.

Further, the top and/or wear layer may include means to reduce static (electrostatic) charging of the final laminate. For example, it can be provided that the cover and/or wear layer has compounds such as choline chloride. The antistatic agent can be present, for example, in a concentration of between >0.1% by weight and <40.0% by weight, preferably between >1.0% by weight and <30.0% by weight, in the cover and/or composition for forming the wear layer.

A transparent wearing layer, for example made of thermoplastic polymers, can also be used, which is applied, for example laminated, to the decorative layer as a film, for example a film web. If necessary, use for sufficient adhesion An adhesion promoter/primer is necessary, which crosslinks with the decorative layer through radiation curing from above ("adhesive lacquer") or thermally seals ("hotmelt"). A thermoplastic wear layer offers further advantages for the recycling process of the entire structure. A surface structuring can be introduced very easily via heated structured metal sheets via a press or structured rollers via a calender (this also synchronous with the decor).

Furthermore, in the method described here, according to method step d), at least one layer to be structured is structured, the layer to be structured being selected from the decorative layer, the intermediate layer and the cover layer. As already explained above, the structuring serves in particular to produce a haptically perceptible structure on the decorative panel and thus to give the most realistic possible impression with regard to the template. The structuring is basically done using a laser and is therefore a so-called laser structuring. Laser structuring is performed using the following process steps.

To carry out the laser structuring according to method step d1), a laser beam is first generated. In principle, the type of generation of the laser beam can be selected. In particular, however, the selection of the beam source and the generated laser beam or its parameters is made as a function of the material of the layer to be structured. At best, the material should be vaporized by the laser beam, so the specific parameters should be adjusted accordingly.

Furthermore, according to method step d2), the laser beam is divided into a matrix of a plurality of partial beams. This step allows the layer to be structured not only to be structured by a single laser beam, but that Rather, structuring can take place simultaneously at a large number of positions. As a result, the throughput and thus the effectiveness of the method can be effectively increased. The individual partial beams can be used in each case in order to produce structures that are separate from one another, or the laser beams can also process the same structure position in succession or simultaneously. Here is the simultaneous

Processing of the same structure position is possible, especially in connection with several scanners and a corresponding overlap of the scan fields.

In this regard, it should be noted that when the laser beam is divided, the performance data for each partial beam is also reduced in relation to the initial beam or, assuming ideal conditions, the sum of partial beams has the same strength as the initially generated laser beam. It is evident from this that in the case of desired deep structures, a plurality of partial beams may be advantageous for processing, whereas fewer partial beams or only one partial beam may be sufficient for structures with a comparatively small depth.

In order to achieve the aforementioned advantages particularly effectively, it can be advantageous that method step d2) takes place with the laser beam being divided into at least 250 partial beams, for example into at least 500 partial beams. This refinement enables a particularly defined structuring and, at the same time, a particularly high level of effectiveness. Furthermore, such a division is possible using known means.

In this regard, it is also preferred if method step d2), ie the division of the laser beam into a matrix of a plurality of partial beams, takes place using a diffractive optical element (DOE). Such an element can, in a manner known per se, be, for example, a glass element which has microstructures, in particular as a two-dimensional optical grating, which generate corresponding partial beams from an initial beam by means of a diffraction pattern. Thus, the diffractive optical element used as a beam splitter. As a further alternative, what is known as a spatial light modulator (SLM) is fundamentally available for method step d2), although the present invention is fundamentally not limited to the examples mentioned.

For example, via two so-called relay lenses, often implemented as a so-called 4f setup, the partial beams are separated and coupled into the modulator as described below. A mask is located between the lenses in the intermediate focus, which filters out the undesired higher diffraction orders.

According to the method described, it is provided, as indicated above, that the partial beams that have taken place in method step d2), ie the matrix of partial beams, are then guided into a modulator for the selective inactivation of individual partial beams. The use of such a modulator in the beam path of the laser beams makes it possible for individual partial beams to be deactivated and thus not reach the layer to be structured or be removed from the beam path. As a result, the range of application of the method can be further improved or the quality and the adaptation of the structure to the template can be improved even further. In particular, it may be possible that, depending on the structure to be produced, not all of the partial beams are required, so that the method can also be used without any problems with structures of this type.

It can also be particularly preferred to use an acousto-optical modulator (AOM) or an electro-optical modulator (EOM) as the modulator. Such modulators in particular make it possible to remove individual partial beams from the beam path leading to the surface to be structured at high speed.

A modulator is to be understood as meaning an optical component that influences, modulates, the frequency and direction of propagation or intensity of incident light. For this an optical lattice is produced in an acousto-optical modulator in a transparent solid body with sound waves. The respective light beam or partial beam is diffracted at this grating and at the same time its frequency is shifted. The deflection of light in a traditional acousto-optical modulator works on the principle of light diffraction on an optical grating. Correspondingly, in the case of an electro-optical modulator, such as a crystal, the optical thickness is changed instantaneously as a function of the strength of an applied external electric field, thus enabling individual partial beams to be deflected. There is thus a modulation of light on the basis of electro-optical crystals.

In particular in connection with an acousto-optical modulator or an electro-optical modulator as described above, it can also be preferred that a beam trap is used in combination with the modulator. This makes it possible to reliably inactivate the partial beams removed from the beam path, so that they do not fall on the surface to be structured, and furthermore they do not have a negative impact or even pose a danger to the environment.

In the method described, according to method step d4) the matrix of partial beams is also routed from the modulator into an optical scanner, the matrix of partial beams after the modulator comprising all or a reduced number of partial beams routed into the modulator. Thus, the matrix of partial beams, which leaves the modulator and which thus has a corresponding pattern of partial beams matched to the structure to be applied, can be guided into the optical scanner. The optical scanner can then direct the corresponding partial beams to the desired position of the layer to be produced, so that a corresponding structuring takes place. The optical scanner can direct all partial beams onto the layer at the same time or, depending on the scanner, different partial beams can also be directed onto the layer to be structured independently of one another. The optical scanner thus serves to direct the partial beams to the correct position of the layer to be structured in a position-accurate manner and as a function of the structure to be produced.

At least one of a polygon scanner and a galvanometer scanner can be used particularly advantageously as the optical scanner. For example, a polygon scanner or a galvanometer scanner or also both a galvanometer scanner and a polygon scanner can be used, in which case, of course, a plurality of galvanometer scanners and/or polygon scanners can also be used.

Such scanners are suitable in particular for working with high dynamics and thereby in particular for enabling a high throughput. Industrial production of decorative panels, in which efficient production can be combined with detailed structuring, can thus become possible, in particular using such scanners. In particular, the scanners mentioned advantageously serve to be able to apply a very delicate structure.

Galvanometric scanners are particularly suitable for applications in which large parts of the processing level are not processed and time is saved by so-called "jumps" between the processing points.

However, if the entire surface is to be structured, polygon scanners are particularly suitable. Cellular processing can be selected using polygon scanners, with scanning speeds > 1 km/s being achievable. In this application, therefore, a combination of partial beams that can be switched by modulators and a polygon scanner as a deflection unit appears to be maximised to be particularly advantageous in terms of productivity. The partial beams can be arranged in an array of any shape, for example square, rectangular, cellular.

Correspondingly, according to method step d5), the matrix of partial beams is guided from the scanner onto the layer to be structured, optionally via suitable focusing optics.

Due to the influence of the partial beams, structuring now takes place in that, according to method step d6), the layer to be structured is negatively structured under the influence of the partial beams or the partial beam array to produce a three-dimensional structure. Negative structuring means structuring in which a structure is introduced from the layer to be structured by selectively reducing the thickness of the corresponding layer, in the present case material is removed from the layer, in particular evaporated, depending on the layer to be produced .

It should also be pointed out that steps d2) to d6) described above preferably proceed in numerical order, although the invention is not restricted to this. In addition, it is possible for further intermediate steps to be inserted, or for the beams to pass through further components between the components mentioned, without departing from the scope of the invention. If it is thus described that the radiation is conducted or runs from one component to another component, this can include direct or immediate conduction without further intermediate components as well as indirect conduction with the interposition of further components. However, it is equally possible for the structuring to take place using only the method steps d1) to d6), the structuring thus consisting of the method steps d1) to d6). The method described here has clear advantages over the methods known from the prior art.

In particular, the method described here can use laser structuring for structuring a decorative panel in such a way that a high throughput and thus an efficient method is possible with very precise structuring at the same time. A particularly high quality of the haptically perceptible structure is thus possible. This applies both to the feel as such, which gives a very realistic impression, and to the design of the structure with reference to a template. Because of the individual process steps, in particular the laser structuring, the template can be imitated right down to the template identity, which can further improve the result of the structuring.

In addition, the method can be particularly effective in that it enables high throughput. Because of the individual process steps, the latter can take place very quickly with a simultaneously high quality of the structuring, so that the web speed of the semi-finished products to be structured for the production of the decorative panels can be very high. This applies equally to a continuous feed as well as to a clocked or sequential feed. Thus, through synergetic effects of the combination of the individual process steps, a structuring can be made possible that can be used on an industrial scale and still does not require any compromises in terms of quality and flexibility. The present invention thus relates in particular to a method by which highly precise structures can be introduced into a panel layer in a simple and adaptable manner with a high throughput by means of laser structuring.

Furthermore, it is possible to introduce the structures in a highly defined manner, so that the layer to be structured, for example a lacquer layer, can be kept very thin. This can have advantages in particular with regard to costs and with regard to weight. However, the recyclability of the panels produced can also be improved in this way. In principle, there is still a high degree of flexibility in terms of structuring, which offers significant advantages, especially in combination with the application of the decor using digital printing.

In method step d6), the layer to be structured can preferably be negatively structured under the action of the partial beams to produce a three-dimensional structure in such a way that a material elevation resulting from material discharge, for example material ejection of molten material, is produced in the edge region of the introduced structure.

A particularly realistic structuring can be produced by this method. This is because sharp edges on the edge of the introduced structure can be prevented. Rather, a rounded edge can be created by increasing the material, which makes the structure haptically very similar to structures to be reproduced, such as wood structures.

The increase in material also makes it easier to depict deep structures. Because the perceived depth of the structure is not only the depth of the structure that is actually introduced, but precisely this depth in addition to the height of the material increase. As a result, deep or deep-acting structures can also be produced without the risk of damaging any decoration that may be present under the structure.

In detail, high-quality decorative panels often strive for the greatest possible structural depth in the range of, for example, 30-250 μm, in particular 80-140 μm, for a realistic reproduction of, for example, wood or stone structures. The increase in material that occurs during the structuring process causes an increase in the haptically and optically perceived structural depth in the layer to be structured, such as the top layer, of such products. Depending on the process parameters, the material increase is in the range of 1-100 μm, for example. The consequence of this is that the thickness of the layer to be structured can be reduced while the structure depth remains the same. This can have the advantage that a higher transmission of the laser radiation in the ablation process can be accepted without damaging a decorative layer that may be present, in order to generate more volume absorption, or that the use of less favorable lasers with regard to the optimal wavelength of the top layer material to be processed is made possible becomes.

Furthermore, a high degree of variability of the method is possible. This is because it becomes possible to form the layer to be structured in the form of a film, for example. The film can be provided with an appropriate structure before lamination and printing. Furthermore, it is also possible to apply the structured film to a carrier that has already been printed, to structure it on the carrier and the film can also be printed from the back. In principle, a so-called “roll to roll” method can also be used, in which the film is unrolled from a roll, structured and stored on a roll until it is applied to a carrier. Alternatively, as indicated above, the film can also be applied to a carrier immediately after structuring.

To control the material discharge, it can be advantageous that at least one of the specific wavelength, the pulse energy, the pulse duration, the spot diameter, the repetition rate, i.e. the frequency of a pulsed laser, and the pulse overlap, i.e. the percentage overlap of individual pulses in the scanning direction, laser radiation impinging on the layer to be structured can be selected based on the material of the layer to be structured. In particular, these parameters can have an influence on the incoming intensity of the radiation and the heat accumulation in the material to be structured and thus directly determine the melt formation that occurs. Exemplary parameters for producing a material increase in transparent polypropylene as a layer to be structured are as follows.

Using a UV-USP laser, the following parameters can be used: - Wavelength: 343 nm

Spot diameter: 50 pm Repetition rate: 100 kHz Pulse energy: 36 pj Pulse length: 300 fs - Pulse overlap: 80% Material increase: 1 pm

Using an IR-USP laser, the following parameters can be used: wavelength: 1030 nm - spot diameter: 58 pm

Repetition rate: 700 kHz Pulse energy: 70 pj Pulse length: 800 fs Pulse overlap: 80% - material increase: 2 pm Using a CC laser, the following parameters can be used: wavelength = 10.2 gm spot diameter = 250 pm repetition rate = 200 kHz pulse energy: 500 pj pulse length: 2 ps pulse overlap: 80% generated material increase: 30 pm

The increase in material can be, for example, in a range from >0 to <100 μm, preferably in the range from >5 to <30 μm.

With regard to the formation of a material increase, the following can be observed.

The removal in the described structuring process is initiated by melting and evaporating the material of the layer to be structured. The recoil of the evaporating molecules causes a partial ejection of the molten material, which accumulates as a material increase at the edge of the structure. In other words, the resulting ablation morphology can have an increase in material in the edge region of the ablation crater in the height profile caused by the melt ejection. The extent of this increase in material is largely determined by the proportion of melt-based to evaporation-based material discharge.

The relationship between the melting and the evaporation-based interaction zone of laser radiation and material can be adjusted in the process preferably via the wavelength, pulse energy and pulse duration as well as spot diameter, repetition rate and pulse overlap of the laser radiation impinging on the layer to be structured. The decisive factor here is the absorption behavior of the radiation in the material of the structuring layer. While for the same energy input, surface absorption maximizes the fraction of evaporation-based erosion, the fraction of melt-based erosion increases with increasing volume absorption due to the lower fraction of energy that is transferred into the material.

According to this principle, material-dependent laser radiation with a specific wavelength, pulse energy and pulse duration can be selected in order to set a desired ratio of melt-based and vaporization-based material removal. The aim is, for example, to maximize the material ejection in the edge area of the introduced structure without causing damage to a potentially present decorative layer under the layer to be structured due to excessive transmission.

In principle, in addition to using only one laser beam source with a specific power, wavelength, beam profile and spot diameter, it is also possible to use a combination of several different beam sources with different power, wavelength, beam profile and spot diameter. For example, the combination of a C0 ₂ laser with a power of 10 kW, a wavelength of 10.25 pm and a spot diameter of 250 pm and a UKP laser with a power of 1 kW, a wavelength of 343 nm and a spot diameter of 50 would be conceivable pm. This can have several advantages on the structuring process. Most of the required material removal could be done via the leading CCk laser spot, whereas the USP laser spot subsequently takes over the fine processing for a higher structure resolution. A corresponding processing system can thus be designed more cost-effectively due to the different prices per service depending on the laser. It would also be conceivable to simply preheat the material using the CO2 laser and remove the material using the UKP laser. It would also be possible to use different beam profiles, for example a classic Gaussian beam profile for the material removal and a ring-shaped beam profile or a so-called top hat Beam profile with an even intensity distribution for preheating the material. The corresponding beam profile can be generated either in the beam source itself or via appropriate optical elements such as axicons, gratings or mirrors in the beam path.

In this configuration, by preventing sharp edges, painting that may take place after the structuring can also take place particularly advantageously. This is because the radii occurring as a result of the increase in the material can allow improved wetting of the surface during painting, as described below.

With regard to the paintability of the structured layer as described above, it can thus be influenced as follows. The ablation morphology that occurs in the structured layer can contribute to improved paintability of the structured surface due to the proportion of melt-based ablation. If the material is discharged mainly via surface absorption of the radiation and thus via evaporation, a more sharp-edged structure with small radii is created in the upper and lower edge area of the crater. Due to the surface tension of paint systems, this can make it difficult to wet the top layer, especially in the lower area of the removal crater. If the material is also discharged via volume absorption and is therefore melt-based, the melt ejection already described results in a less sharp-edged structure with larger radii in the upper and lower area of the removal cat. This can promote wetting when painting the structured surface compared to the predominantly evaporation-based structuring.

With regard to the laser structuring, it can also be advantageous that method step d) is carried out using a laser that is selected from an ultra-short-pulse laser, a CO2 laser and an excimer laser. Especially using With the laser sources described above, the method and, in particular, the partial steps of laser structuring described can be carried out effectively, so that a convincing structuring result is possible. If an ultra-short-pulse laser, also referred to as a USP laser, is used in the laser structuring, it may be preferable for method step d) to be carried out using an ultra-short-pulse laser, with a wavelength of the laser beam generated in one The range is from > 150 nm to < 1070 nm, the laser working with a power that is in a range from > 500 W to < 100000 W and the laser beam has a beam diameter in a range from > 10 gm to < 500 gm. Using these parameters, it can preferably be achieved that the material of the layer to be structured evaporates and the negative structuring can thus take place reliably. In addition, very fine structures can also be produced with a high contrast, which makes the result of the structuring appear particularly realistic.

In principle, and for all lasers used, it should be pointed out that the wavelength and the beam diameter apply equally to the initial beam that is generated and to the partial beams that are generated. The power, on the other hand, is reduced from the stated power of the initial beam to the power of the partial beams, depending on the number of partial beams generated.

In method step d), the laser beam can particularly preferably be generated in a pulsed manner, with a pulse frequency in a range of <100 MHz and a pulse duration in a range of <1000 ns, for example from >100 fs to <1000 ns. This refinement is possible in particular using an ultra-short-pulse laser. Such a pulsed application of the laser beam enables in particular the lowest possible thermal stress on the layer to be structured or on the material of the structuring layer. A particularly high surface quality of the structured layer can thus be made possible.

Furthermore, in particular a combination of an ultra-short-pulse laser in method step d1) and a polygon scanner as an optical scanner in method step d5) can offer advantages. For material removal with the lowest possible melt formation and the lowest possible thermal stress on the workpiece, the required laser power of USP lasers is typically in a maximum range of 50 W. In order to use the increasing average laser power of USP lasers for higher productivity use, polygon scanners in particular offer a promising possibility. These allow high scanning speeds of >1 km/s on the workpiece in connection with high repetition rates. Splitting the laser beam into an array of partial beams, which is moved over the workpiece with a galvanometer scanner, can also help to reduce the thermal load on the workpiece, even at high power densities.

More preferably and in particular as an alternative to using a USP laser, method step d) can be carried out using a CO ₂ laser, with a wavelength of the laser beam generated being in a range from >9.8 pm to <10.6 pm, wherein the laser operates with a power ranging from >500 W to <100,000 W, the laser beam having a beam diameter ranging from >150 μm to <1000 μm.

Such lasers are also advantageously suitable for the method described here and are also available on the market in large numbers and in many variations. As a result, good adaptability to the desired specific application or to the desired result can be possible, in particular when using CCk lasers. As a further alternative, method step d) can be carried out using an excimer laser, with a wavelength of the laser beam generated being in a range from >100 nm to <380 nm, with the laser operating at a power that is in a range from > 1000 W to <100,000 W, the laser beam having a beam diameter in a range from >150 gm to <1000 gm, approximately up to <500 gm can keep low.

More preferably, the method has the further method step before method step d5): d7) guiding the laser beams through a scanning lens, in particular through an f-theta lens. The use of a scan lens, in particular an f-theta lens, allows the laser beams or the laser focus to be positioned on a flat image field, ie the flat surface of the layer to be structured. The focus size can remain almost constant. A particularly defined structuring can thus take place through the use of a scanning objective, it also being possible for particularly fine structures to be represented with high quality.

For example, a film-like intermediate layer can be applied to the decoration in method step c) and the intermediate layer can be structured in method step d). The intermediate layer, for example the film-like intermediate layer, can be made in particular from a plastic such as polypropylene.

In principle, as already indicated above, it is possible at various points to provide a relay lens package, for example with two lenses, in the beam path. As a result, the partial beams can be spatially separated. If necessary, this can create opportunities to introduce further components, such as a mask. Furthermore, through the relay lens pack coupling into optical components such as a modulator or a Scanner, advantageously enabled or improved. For example, the lens package can be implemented as a so-called 4f setup, where 4f refers to the arrangement of the modules or the distances and f stands for the focal length of the lenses.

The invention is explained in more detail below with reference to a figure.

Fig. 1 shows a schematic implementation of the method according to the invention.

In FIG. 1, the implementation of the method according to the invention is shown schematically.

In detail, FIG. 1 first shows a beam source 10 which generates a laser beam 12 . The beam source 10 in the configuration according to FIG is from > 500 W to < 100,000 W and the laser beam 12 has a beam diameter in a range from > 10 pm to < 500 gm Furthermore, the laser beam 12 is generated in pulses, with a pulse frequency in a range of < 100 MHz and a pulse duration in a range from >100 fs to < 1000 ns is used.

The laser beam 12 that is generated now impinges on a diffractive optical element 14, in which the laser beam 12 is divided into a matrix 16 of a plurality of partial beams. For example, the laser beam can be divided into more than 250 partial beams or far more. Depending on the design of the diffractive optical element 14, an incoming laser beam 12 can be divided into a desired number of main diffraction orders and thus partial beams.

The partial beams can be coupled into the deflection unit and spatially separated via a relay lens package, for example with two lenses 18, 20, often implemented as a so-called 4f setup will. Furthermore, a mask 22 is provided between the lenses 18, 20 in the intermediate focus, which mask can filter out the undesired higher orders of diffraction. A so-called acousto-optical multi-channel modulator (AOMC) is also provided behind the mask 22 and in front of the second lens 20 as an example of an acousto-optical modulator (AOM) or a modulator 24 . In an AOM, an optical lattice is generated during switching by sound waves in a transparent solid, which bends and deflects the partial beams, usually into a beam trap. This serves to selectively deactivate individual sub-beams.

It is fundamentally possible to use a plurality of individual AOMs in order to process the matrix 16 of partial beams completely by a modulator 24 and to be able to modulate or switch the partial beams individually. In contrast, multi-channel AOMs allow the modulation of several individual sub-beams. In principle, a plurality of modulators 24 or one or more multi-channel modulators 24 can thus be used.

FIG. 1 now shows schematically that after the modulator 24 there is a reduced number of partial beams in the matrix 16 and this is now directed into an optical scanner 26 as a deflection unit. The partial beams can be guided at high speed by the scanner 26 onto a surface to be structured or a layer 28 to be structured of a semifinished product 30 for a decorative panel. The optical scanner 26 is in particular a polygon scanner.

More precisely, after exiting the scanner 26, the partial beams can be focused through an f-theta lens 32 onto the workpiece or the layer 28 to be structured. f-Theta lenses are used in particular because on the one hand they keep the laser spot in focus when the radiation is deflected on the workpiece and on the other hand they partially eliminate the distortions of the scan field that occur in mirror-based 2D scanning systems compensate and thus enable constant scanning speeds on the workpiece.

Basically and independently of the specific configuration, the following should be mentioned. In addition to distortions caused by the deflection system and the focusing optics, the diffractive optical element 14 can already lead to distortions in the processing plane, which can increase as a result of an increasing distance between the partial beams and with an increasing number of beams in the matrix 16 . In addition to optical compensation approaches, such as the f-thetha lens 32, this problem can be circumvented by creating a software-based, scanner-based correction of the scan vectors for each individual partial beam. However, an additional compensation for the distortion by any optical components, such as the f-thetha lens 32, can nevertheless be alternatively or additionally possible. FIG. 1 also shows schematically that the layer 28 to be structured is negatively structured under the influence of the matrix 16 on partial beams to produce a three-dimensional structure 34 . In this case, the layer 28 to be structured can be a film, for example made of polypropylene, which is applied to a decorative layer. Furthermore, it is possible that a material elevation resulting from material discharge is produced in the edge region of the introduced structure 34 .

Subsequent to the structuring shown, a cover layer can optionally be applied to the structured layer to produce the finished decorative panel. Furthermore, peripheral locking means can be introduced, which can allow the panel to be locked to other panels, for example to produce a floor covering. An exemplary configuration for structuring can be possible as follows.

The following setup would be possible as an example for processing panels measuring 1300 x 1280 mm. A total of nine polygon scanners with a scan field size of 450 mm ² x 450 mm ² and a spot size of the partial beams of 50 pm can be used. Furthermore, a pulse overlap of the respective pulses generated by the scanners of 50% can also be used. Furthermore, a number of ablation layers of 160 can be used, so that with a structure depth of 80 μm, 0.5 μm is ablated per layer or per processing.

A processing time per panel can be 2.229 s, with a panel feed rate of around 35 m/min.

Furthermore, 740 switchable partial beams of 45 watts each (fluence 0.08 J/cm ² ) can be processed per scanner 26, which are divided and arranged in lines by means of a DOE 14 and can be switched by corresponding AOMs. The distance between each partial beam impinging on the panel can be around 600 μm.

In this configuration, the processing speed of the polygon scanner can be 717 m/s and the required laser power can be 300 kW and the required repetition rate or frequency of the EIKP laser can be 28.68 MHz. The pulse length can be <10 ps, preferably <1 ps.

With the values mentioned, i.e. panel size and processing parameters of the panels, there can be a vector length per panel, i.e. the total length of the laser processing lines caused by all processing, calculated from the length of the lines per panel x number of processed layers, of 10649600 m. R eference list

10 beam source 12 laser beam

14 diffractive optical element 16 matrix

18 lens

20 lens 22 mask

24 modulator

26 scanners

28 layer

30 semi-finished 32 f-thetha lens

34 structure

Claims

patent claims

1. A method for producing a decorative panel, comprising the method steps: a) applying a decorative layer to a carrier, b) optionally applying an intermediate layer to the decorative layer, c) applying a top layer to the decorative layer or the intermediate layer, and d) structuring at least one structuring layer (28), wherein the layer (28) to be structured is selected from the group consisting of the decorative layer, the intermediate layer and the top layer, characterized in that

Method step d) comprises the method steps: dl) generating a laser beam (12); d2) dividing the laser beam (12) into a matrix (16) of a plurality of partial beams; d3) directing the matrix (16) of sub-beams into a modulator (24) for selectively inactivating individual sub-beams; d4) guiding the matrix (16) of partial beams from the modulator (24) into an optical scanner (26), the matrix (16) of partial beams after the modulator (24) all being guided into the modulator (24) or one reduced thereto Number of sub-beams included; and d5) directing the matrix (16) to partial beams from the scanner (26) onto the layer (28) to be structured; d6) the layer (28) to be structured being negatively structured under the action of the partial beams to produce a three-dimensional structure (34).

2. The method according to claim 1, characterized in that in method step d6) the layer to be structured (28) under the action of the partial beams for generating a three-dimensional structure (34) is negatively structured in such a way that a material increase resulting from material discharge is produced in the edge region of the introduced structure (34).

3. The method according to claim 2, characterized in that to control the material discharge at least one of the specific wavelength, the pulse energy, the pulse duration, the spot diameter, the repetition rate, and the pulse overlap of the laser radiation impinging on the layer to be structured is selected based on the Material of the layer (28) to be structured.

4. The method according to any one of claims 1 to 3, characterized in that the modulator (24) is used in combination with at least one beam trap.

5. The method according to any one of claims 1 to 4, characterized in that

Process step d2) takes place by dividing the laser beam (12) into at least 250 partial beams.

6. The method according to any one of claims 1 to 5, characterized in that at least one of a polygon scanner and a galvanometer scanner is used as the optical scanner (26).

7. The method according to any one of claims 1 to 6, characterized in that

Method step d) is carried out using an ultra-short pulse laser, with a wavelength of the laser beam (12) generated being in a range from >150 nm to <1070 nm, with the laser operating at a power that is in a range is from> 500 W to <100000 W and wherein the laser beam (12) has a beam diameter in a range from> 10 pm to <500 pm.

8. The method according to claim 7, characterized in that in method step d) the laser beam (12) is generated in a pulsed manner, a pulse frequency in a range of <100 MHz and a pulse duration in a range of >100 fs to <1000 ns being used .

9. The method according to any one of claims 7 or 8, characterized in that in method step d1) an ultra-short pulse laser is used as the beam source (10) and in method step d5) a polygon scanner is used as the optical scanner (26).

10. The method according to any one of claims 1 to 9, characterized in that method step d) is carried out using a CCk laser, wherein a wavelength of the generated laser beam (12) is in a range from> 9.8 pm to <10, 6 pm, the laser working with a power in a range from >500 W to <100000 W, the laser beam (12) having a beam diameter in a range from >150 pm to <1000 pm.

11. The method according to any one of claims 1 to 10, characterized in that method step d) is carried out using an excimer laser, wherein a wavelength of the generated laser beam (12) is in a range from> 100 nm to <380 nm, wherein the laser operates with a power in a range from >1000 W to <100000 W, the laser beam (12) having a beam diameter in a range from >10 pm to <1000 pm.

12. The method according to any one of the preceding claims, characterized in that the method has the further method step before method step d5): d7) guiding the matrix (16) to partial beams through a scanning lens, in particular through an f-theta lens (32) .

13. The method according to any one of the preceding claims, characterized in that the laser beam in method step d2) is divided by a diffractive optical element (14) into a plurality of partial beams.

14. The method according to any one of the preceding claims, characterized in that in method step c) a foil-like intermediate layer is applied to the decoration and the intermediate layer is structured in method step d).

15. The method according to claim 14, characterized in that the intermediate layer is formed from a thermoplastic material, an aminoplast or a lacquer.