Method for finishing a wood-based panel

Abstract

The invention relates to a method for finishing a wood-based panel which has a top side, wherein the method comprises the following steps: a) providing an unprinted raw paper having a surface to be printed; b) applying a resin-containing liquid to the surface such that the surface is impregnated with the resin-containing liquid; c) printing the surface impregnated with the resin-containing liquid with a decorative pattern by means of a digital printing installation, so that a printed paper is produced; d) forming a stack of material to be pressed, wherein the printed paper is placed onto the top side of the wood-based panel; and e) pressing the stack of material to be pressed under an elevated pressure and at an elevated temperature.

Description

[0001] G intraallemctumal pr Lopienrtsy

[0002] Flooring Technologies Ltd. Legal file:

[0003] SmartCity Malta SCM01 , Office 406 2459-0777 PCT-1

[0004] Ricasoli, Kalkara SCM1001 Date:

[0005] Malta, December 18, 2025

[0006] Method for refining a wood-based panel

[0007] The invention relates to a method for finishing a wood-based panel, in which a paper printed with a decor is placed on the top surface of a wood-based panel, so that a stack of pressed material is formed which is pressed under increased pressure and increased temperature.

[0008] Such a method is disclosed, for example, in DE 102007 012 236 B4.

[0009] In the process described therein, a paper substrate is first applied to the top surface of the wood-based panel. A decorative layer is then applied to this substrate, followed by a sealing lacquer layer. The lacquer layer is then completely cured using electron beams, and a structure is embossed into the lacquer layer.

[0010] Individual panels are then cut from a large-format laminate sheet that has been finished in this or another way; these panels can then be used as flooring, wall coverings, or ceiling coverings. The panels are preferably provided with a tongue-and-groove joint on their side edges; this also applies to finished wood-based panels that have been finished according to a method according to the present invention.

[0011] A problem with laminates containing a paper structure, a known issue in the art, is delamination, which occurs wherever materials are bonded together layer by layer with the addition of binders, heat, and pressure. Delamination is often visible externally as blisters, or the paper layer may detach from the panel at the edges. To prevent delamination, some manufacturers have resorted to directly coating the panels.

[0012] DE 197 51 115 A1 discloses a method for coating a panel in which at least one layer of color is applied to the surface by means of a printing process, in particular by means of screen printing. The surface can be untreated, sanded or pretreated, in particular painted.

[0013] Finally, the applied layer of paint can be covered with a coating of clear varnish.

[0014] German patent DE 10 2004 026 739 A1 describes a process in which a primer is applied to the top surface of a wood-based panel using a roller and allowed to dry. A first and second coat of lacquer are then applied to the dried primer, which cures under the influence of UV light, although the curing process is not fully completed. Finally, a UV-curing topcoat is applied to the first two coats, and the top coat is then plastically deformed. Direct printing is very expensive and must be carried out with great care to avoid inclusions in the print. Furthermore, it is important that each individual layer is sufficiently dry before the next layer is applied in liquid form to prevent the colors from bleeding together.

[0015] When using direct printing technology, i.e., the direct printing of individual layers onto a substrate, the finished laminate panels are thinner than those produced using conventional methods due to the omission of paper layers. This leads to problems in continuous production when the large-format coated laminate sheets are subsequently cut to size for panel manufacturing. To ensure that individual panels do not fall below the thickness specifications of DIN 13329, stringent quality control is required, which slows down production and further increases manufacturing costs. Ultimately, this also causes confusion for retailers and / or end consumers, as the stack height of directly coated panels differs noticeably from that of panels coated with paper layers.

[0016] In conventional panel manufacturing, HDF or MDF panels are typically used as the core board, the top surface of which is sanded down by approximately 0.3 mm. A pressed layer, also known as a press patina or deterioration layer, forms on the top and bottom surfaces of the core board. This pressed layer is created during the pressing of the fiberboard and is generated by the hot surface of the press plates or belts. The pressed layer is approximately 0.3 mm thick. Since the pressed layer is completely sanded off, along with approximately 0.1 mm of the core material, to reduce the surface roughness on the top of the panel before further coating, the panels must be manufactured with a corresponding sanding allowance, which significantly impacts production costs. To produce a standard-compliant, direct-print laminate flooring with a thickness of 6.0 mm, the core board must be at least 6.1 mm thick.

[0017] EP 2 236 313, for example, describes how the pressing surface must be sanded down because the heat input during hot pressing is so high in this area that the adhesive hardens too quickly, causing the adhesive bonds to break, at least partially, and making the applied layer vulnerable. This breaking of the adhesive bonds makes finished panels susceptible to delamination of the decorative and abrasion-resistant layers applied to the substrate. This delamination, which can occur even under normal stress and on a scale typical for wood-based materials due to climatic fluctuations, is not tolerated by the customer.

[0018] EP 3 023 261 A1 describes a process in which the decor is applied to a decorative paper that is impregnated and completely saturated with a synthetic resin. The pressed skin that forms during the production of the wood-based panel is not removed; instead, a further layer of synthetic resin is applied to the wood-based panel before the resulting stack of panels is pressed. This is intended to prevent or at least reduce delamination.

[0019] A disadvantage of this process is that it is time-consuming and expensive due to the large quantities of synthetic resin that are applied to the wood-based panel and embedded in the decorative paper during the various work steps. Furthermore, large amounts of liquid are used in the process, often requiring intensive drying, which further extends the overall timeframe.

[0020] Another difficulty is that, in order to reduce costs, paper with the lowest possible grammage, for example 65 g / m², is needed. 2 or even just 50 g / m² 2 A primer is typically applied to prevent the printing ink from fully penetrating the paper and thus impairing the color effect on the paper's surface. This incurs additional costs and introduces extra liquid to the paper, the water content of which must be removed through further drying steps before the prepared paper can be processed and printed on.

[0021] The invention is based on the objective of proposing a method that avoids or at least reduces the disadvantages of the prior art.

[0022] The invention solves the stated problem by a method for finishing a wood-based panel having a top surface, the method comprising the following steps: a. providing an unprinted raw paper with a surface to be printed, b. applying a resin-containing liquid to the surface so that the surface is impregnated with the resin-containing liquid, c. printing the surface impregnated with the resin-containing liquid with a design using a digital printing system, so that a printed paper is produced, d. forming a stack of pressed material, wherein the printed paper is placed on the top surface of the wood-based panel, and e. pressing the stack of pressed material under increased pressure and temperature.

[0023] First, the unprinted raw paper is provided, which, for example, has a basis weight of 50 g / m². 2 or 65 g / m² 2The process involves applying a resinous liquid to the surface of this unprinted raw paper, so that the surface is saturated with the resinous liquid. This means that preferably the entire surface is wetted with the resinous liquid. However, the raw paper is not impregnated, i.e., completely permeated, with the resinous liquid. Rather, preferably an amount of the resinous liquid is applied that is sufficient to saturate the surface of the paper, but not sufficient to completely impregnate the paper.

[0024] Preferably less than 15 g / m² 2 , preferably less than 10 g / m² 2 , particularly preferably less than 8 g / m³ 2 , and at least 5 g / m² 2 , preferably at least 6 g / m² 2 , particularly preferably at least 7 g / m³ 2 applied to the resinous liquid.

[0025] The resinous liquid contains at least one synthetic resin, but preferably does not consist entirely of it.

[0026] After the resin-containing liquid has been applied to the surface of the paper, the design is printed onto the resin-impregnated surface. Preferably, the paper is first dried in a dryer to reduce its moisture content. The design is printed in a digital printing system, preferably a single-pass digital printing system. In such a single-pass digital printing system, the paper to be printed passes the printheads of the system only once. Preferably, the digital printing system has printheads that extend across the entire printing width, with separate printheads for each of the printing inks used being particularly preferred. The printing inks used are preferably cyan, red, yellow, and black (CRYK). Water-based inks are particularly preferred.

[0027] The printed paper is preferably dried in a dryer to reduce its moisture content. The printed paper is then placed on the top surface of the wood-based panel to be finished. The top surface of the wood-based panel is preferably sanded. A synthetic resin is preferably applied to the top surface of the wood-based panel. This synthetic resin is preferably the same resin contained in the resinous liquid.

[0028] The stack of material to be pressed, which includes the wood-based panel and the printed paper placed on its top surface, is pressed under increased pressure and temperature, preferably using a short-cycle press.

[0029] In a preferred embodiment, the resinous liquid contains or consists of melamine resin and / or urea resin.

[0030] Advantageously, the resinous liquid contains a primer and / or at least one substance that improves the adhesion of ink applied during printing. In a particularly simple embodiment of the invention, the resinous liquid contains a mixture of a synthetic resin and a primer. It is advantageous if the proportion of the primer in the mixture is as small as possible but sufficient to achieve the desired color effect of the decoration. For example, the proportion of the primer in the mixture is such that at least 1 g / m³ is present in the resinous liquid. 2 , preferably at least 1.5 g / m³ 2 , particularly preferably at least 2 g / m³ 2 and at most 4 g / m² 2 preferably not more than 3.5 g / m³ 2 , particularly preferably not more than 3 g / m³ 2Primer is applied. Preferably, the proportion of primer in the mixture is at most 40 wt.%, more preferably at most 30 wt.%, and particularly preferably at most 20 wt.%.

[0031] Alternatively or additionally, the resinous liquid contains at least one synthetic resin to which substances are added that improve the adhesion of the inks used in printing the decor, especially the pigments. These substances can be called primers or wetting agents. If no mixture of a synthetic resin and a primer is used, the proportion of synthetic resin in the resinous liquid is higher, so that more synthetic resin is available to be used when the stack of panels is subsequently pressed to produce the laminate board. In this case, the amount of synthetic resin that needs to be applied to the surface of the wood-based panel can be reduced.

[0032] Preferably, the resin-containing liquid is applied to the surface of the base paper in such a way that it does not completely penetrate the paper, at least not entirely. There may be individual spots or areas where the resin-containing liquid completely penetrates the paper, but preferably no such spots or areas are present. In a particularly preferred embodiment, the resin-containing liquid is applied to the surface of the base paper using an application roller. The application roller is preferably a roller with a rubber surface. Preferably, the application roller is unstructured. This means that the surface in contact with the base paper has no raised or recessed structural elements.

[0033] Alternatively or additionally, the resin-containing liquid is sprayed onto the surface of the base paper. For this purpose, the device has at least one, preferably several, nozzles through which the resin-containing liquid is sprayed onto the surface of the base paper. Preferably, the nozzles are arranged such that a homogeneous distribution of the resin-containing liquid is achieved on the sprayed surface. By using several nozzles, which can preferably be controlled individually and independently of one another, inhomogeneous distributions of the resin-containing liquid on the sprayed surface can also be achieved. This is useful, for example, if the required amount of primer or primer substances is not identical everywhere on the surface to be printed, for example, because the decoration requires different amounts of printing ink in some places and in some areas.In this case, the areas to be printed with a lot of ink are preferably also sprayed with a larger amount of primer.

[0034] In a particularly advantageous configuration, the resin and primer(s) are mixed directly in front of the nozzles, or separate nozzles are used for the resin and the primer(s), allowing the materials to be sprayed separately. This enables areas requiring less primer to be sprayed with a larger quantity of resin. This ensures, for example, that the surface of the raw paper is sprayed with a homogeneous amount of liquid. This is especially beneficial for subsequent drying, as it allows the surface to dry uniformly. The paper growth induced by the applied liquid can also be homogeneous and therefore easier to manage.

[0035] In a preferred embodiment, the resin-containing liquid is applied using two application units, one application unit being provided for the primer and another application unit for the synthetic resin.

[0036] Preferably, the printed paper is impregnated with a synthetic resin or a synthetic resin mixture before being applied to the top surface of the wood-based panel. It has proven advantageous if the printed paper is impregnated with the same synthetic resin or synthetic resin mixture that was applied to the unprinted base paper and / or to the top surface of the wood-based panel. Preferably, at least one layer of a synthetic resin or a synthetic resin mixture is applied to the top surface of the wood-based panel before the printed paper is applied to it.

[0037] Advantageously, the raw paper is dried in at least one dryer after the application of the resinous liquid and before printing with the decoration.

[0038] In a preferred embodiment, an overlay paper is placed on top of the printed paper placed on the upper side of the wood-based panel when forming the pressable material stack.

[0039] Preferably, the pressed material stack includes an overlay paper that is placed on the top side of the decorative paper laid on the wood-based panel. The advantage of this is that the overlay paper increases the strength of the pressed composite. Preferably, the overlay paper is placed on the top side of the decorative paper so that one side of the overlay paper faces upwards. Preferably, a resin, for example, the first resin or the second resin, is applied to one side and / or one side of the overlay paper. This further increases the strength of the pressed composite. Preferably, the overlay paper is at least partially, but preferably completely, transparent after the pressed material stack has been compressed. Preferably, the overlay paper has a basis weight of no more than 50 g / m². 2 , preferably no more than 40 g / m² 2 , preferably no more than 30 g / m² 2 , in particular a maximum of 20 g / m² 2The overlay paper is preferably not additionally resin-coated.

[0040] Example 1 - Inline impregnation with melamine resin and primer as a mixture

[0041] In a first concrete embodiment of the invention, a paper with a basis weight of 65 g / m² was used. 2 The example was carried out in three different variations, which differ primarily in the resin-containing liquid used. In the first variation, 30 kg of melamine resin was mixed with 10 kg of primer concentrate and used as the resin-containing liquid.

[0042] In the second variant, a mixture of 20 kg melamine resin, 20 kg primer concentrate, 180 g of hardener, and 120 g of wetting agent was used as the resinous liquid. The viscosity of the resin and the primer concentrate was measured using a 4 mm flow cup, which can also be used for the measurement method according to DIN 53211. Flow times of 27 s for the resin and 165 s for the primer concentrate were obtained. The solids content within the resin was between 60% and 65%, and within the primer concentrate between 16.1% and 18.3%.

[0043] In the third variant, the same composition was used as in the second variant, but with a resin whose flow time was only 24 s.

[0044] For all three variants, the moisture content of the printed paper, impregnated with the resinous liquid, ranged from 5.9% to 6.4%. This was followed by drying to a moisture content of 4.2% to 4.7% using infrared radiation at approximately 82°C. The finished impregnates were then pressed in a short-cycle press. Prior to pressing, the sheets were heated with infrared emitters and then coated with melamine resin as a substrate. Without intermediate drying, the paper and an overlay were then applied, and this stack of impregnated sheets was pressed in the short-cycle press.

[0045] Preferably, a first resin is applied using the resin-containing liquid. The process then comprises the following steps:

[0046] Providing an unprinted raw paper with a surface to be printed (top side),

[0047] Printing a design onto the surface using a printing system to create decorative paper,

[0048] Assembling a stack of pressed material that includes at least the wood-based panel and the decorative paper, and

[0049] Compressing the stack of material under increased pressure and / or increased temperature, the process being characterized by the following step:

[0050] Applying the resinous liquid and thus a first resin to the unprinted raw paper, wherein the application of the first resin takes place at least partially, preferably completely, before the printing of the decoration.

[0051] The unprinted raw paper preferably has a basis weight between 40 g / m². 2 and 100 g / m² 2 , for example 50 g / m² 2 or 65 g / m² 2 , on.

[0052] This design allows for a reduction in the amount of resin, particularly melamine resin, required for finishing the wood-based panel. This lowers production costs and improves the compressibility of the pressed material stack. In the past, pressing problems arose when using large quantities of resin. The inventive method can eliminate or at least mitigate these issues.

[0053] The first resin is applied at least partially, but preferably completely, before the design is printed. The surprising advantage of this embodiment is that printing ink can be saved, since the prior application of the first resin surprisingly improves the adhesion of the primer and / or the printing ink to the surface to be printed, resulting in more intense colors with the same amount of ink. This advantage is particularly pronounced when the first resin is applied only to the surface to be printed (top side) or at least also to the top side of the base paper before the design is printed. Alternatively or additionally, the first resin is applied at least partially, and in particular completely, after the design has been printed. Preferably, the first resin is applied in the digital printing system that also prints the design.This makes it possible to control the growth of the paper very precisely. However, during impregnation, irregular growth of the paper can occur, which leads to problems and difficulties during the subsequent printing of the decoration, especially if a structure corresponding to the decoration (synchronous pore) is to be pressed into the surface later.

[0054] Advantageously, several designs are printed onto the surface of the base paper. The designs are preferably essentially identical. Alternatively, the designs can also be different.

[0055] Preferably, the decorative paper is part of a paper web. The paper web preferably has at least one, and preferably several, decorative papers. Preferably, the paper web is a single piece. Preferably, the paper web is rolled into a roll after the decoration has been printed on it. Preferably, the first resin is applied before the paper web is rolled into a roll. Preferably, the decorative paper is cut or die-cut from the paper web before the press stack is assembled.

[0056] Preferably, the raw paper is placed on the top surface of the wood-based panel before the decoration is printed on it, most preferably by laminating it. The raw paper is placed on the wood-based panel, preferably by laminating it, and printed with the decoration in this state.

[0057] In a particularly preferred embodiment, a second resin is applied to the top surface of the wood-based panel before the base paper is laid on it, preferably before it is laminated. Preferably, the base paper is laid on or laminated onto the wood-based panel while the second resin is still wet. The still-moist resin ensures good adhesion, holding the base paper firmly to the top surface of the wood-based panel. In this state, the base paper can be printed with the decorative design particularly easily. Due to the preferably full-surface bond between the wood-based panel and the base paper, which is caused by the second resin, no paper growth occurs after the decorative design is printed onto the surface of the decorative paper, even though the printing process may introduce considerable amounts of moisture.In another embodiment, the raw paper is printed with the decorative design before being placed on the wood-based panel. In this case, the stack of pressed material is formed, among other things, by placing the printed decorative paper on the top surface of the wood-based panel.

[0058] The first resin is preferably applied to the raw paper before the surface is printed. If the raw paper is printed with the decor in its laminated state, the first resin is preferably applied to the unprinted raw paper before the raw paper is mounted on the wood-based panel. An advantageous step of the process involves first applying the first resin to the unprinted raw paper and the second resin to the top surface of the wood-based panel. The raw paper coated with the first resin is then placed on the wood-based panel, preferably laminated, and then printed with the decor.

[0059] Another process involves applying the first resin to the unprinted base paper, which is then printed with the decorative design. Only in this printed state, as decorative paper, is the paper then applied to the wood-based panel, preferably laminated, after the panel has been coated with the second resin.

[0060] Preferably, the first resin is applied only to the side of the paper that faces the wood-based panel and that is not printed with the decoration.

[0061] Preferably, the second resin is applied to the top surface of the wood-based panel before the press stack is assembled. An advantage of this design is that the resin impregnation of the decorative paper and the wood-based panel no longer needs to be carried out in a separate impregnation plant. Surprisingly, in some embodiments, this design allows for integration into a single overall process for finishing a wood-based panel. Previously, separate impregnation in a complex impregnation plant was always required, which often cannot be located on-site, resulting in particularly high transport costs. This reduces manufacturing costs and the required production time. In some embodiments, less space is also required for the production machinery.Advantages arise particularly from combining this process with the resin impregnation of the unprinted base paper and / or the decorative paper, as the amount of resin required for the decorative paper can be reduced, thus making the unprinted base paper easier to print. Furthermore, the risk of delamination can be reduced. In some embodiments, the application of the first resin can be carried out using standard application rollers from laminate production and therefore no longer requires a separate impregnation unit with an impregnation bath.

[0062] Preferably, the second resin is applied to the underside of the wood-based panel before the pressed material is assembled. This counter-tensioning allows for the compensation of deformations caused by the first resin and, if applicable, the second resin on the top side of the wood-based panel. The underside of the wood-based panel is preferably spaced from the top side by a thickness equal to the thickness of the wood-based panel.

[0063] Preferably, the wood-based panel is heated before the second resin is applied. Particularly in this embodiment, drying of the second resin after its application and before pressing the stack of pressed material is not necessary.

[0064] Preferably, the first resin is applied to the underside and / or the surface to be printed (top side) of the unprinted base paper and / or the decorative paper. Preferably, the first resin is applied only to the underside of the unprinted base paper and / or the decorative paper. An advantage of this embodiment is that the unprinted base paper and / or the decorative paper is easier to handle and the resin has no or only a minimal effect on the print quality. Alternatively, the first resin is applied only to the top side of the unprinted base paper and / or the decorative paper.

[0065] Preferably, the entire surface of the top and / or bottom of the unprinted base paper and / or the decorative paper is wetted with the first resin. Preferably, the base paper is not completely, or at least not entirely, penetrated by the first resin. For example, it may be advantageous that only the underside of the unprinted base paper is wetted with resin and that the paper is not completely penetrated by the first resin. Preferably, an amount of the first resin is applied that is sufficient to wet the top or bottom of the unprinted base paper and / or the decorative paper, but not sufficient to completely penetrate the paper.

[0066] Preferably, the first resin is applied with an amount of at least 2 g / m². 2 , preferably at least 5 g / m² 2 , in particular at least 10 g / m² 2 , applied. The first resin is preferred, with a quantity of no more than 50 g / m².2 , preferably no more than 20 g / m² 2 , preferably no more than 10 g / m² 2 , in particular a maximum of 5 g / m² 2 , upset.

[0067] The second resin is preferred, with a quantity of at least 10 g / m². 2 , preferably at least 20 g / m² 2 , in particular at least 30 g / m² 2 , applied. The second resin is preferred, with a quantity of no more than 50 g / m². 2 , preferably no more than 30 g / m² 2 , in particular a maximum of 20 g / m² 2 , applied. These application quantities ensure sufficient bond strength of the laminate composite.

[0068] Preferably, the second resin is applied in a larger quantity than the first. This improves the handling of the base paper and / or the decorative paper. Alternatively, the second resin is applied in the same quantity as the first resin or in a smaller quantity.

[0069] Preferably, the first resin and / or the second resin comprises or consists of a synthetic resin, in particular a melamine resin and / or a urea resin. Preferably, the first resin and / or the second resin comprises at least one additive, preferably a hardener, a wetting agent, and / or thermoplastic polymers.

[0070] In a preferred embodiment, the first resin and / or the second resin is applied by brushing, rolling, troweling, and / or spraying. Particularly preferably, the first resin and / or the second resin is applied using at least one application roller. The at least one application roller preferably has a rubber surface. Preferably, the application roller is unstructured. This means that the surface of the application roller that comes into contact with the base paper and / or the decorative paper has no raised or recessed structural elements. Alternatively or additionally, at least one application roller for the first resin and / or the second resin is structured.

[0071] Alternatively or additionally, the first resin and / or the second resin is sprayed onto the unprinted base paper and / or the decorative paper. For this purpose, the manufacturing device has at least one, preferably several, nozzles through which the first resin and / or the second resin is sprayed onto the unprinted base paper and / or the decorative paper. Preferably, several nozzles are arranged side by side and / or one behind the other. Preferably, the first resin and / or the second resin is applied homogeneously through the at least one nozzle. Alternatively, the first resin and / or the second resin is applied inhomogeneously through the at least one nozzle. For this purpose, the nozzles are preferably individually and independently controllable. Preferably, the first resin and the second resin are applied through different nozzles. Alternatively, the first resin and the second resin are applied through the same nozzles.

[0072] Preferably, the first resin and / or the second resin is applied in liquid form. Preferably, the first resin and / or the second resin is mixed with water to form a resin-water mixture before application. The water content of the resin-water mixture is preferably at least 20%, more preferably at least 30%, and particularly at least 40%. More preferably, the water content of the resin-water mixture is at most 60%, more preferably at most 50%, and particularly at most 40%. Alternatively or additionally, the first resin and / or the second resin can be applied in a solid form.

[0073] Preferably, the first resin is applied from above to the underside and / or the top side of the unprinted base paper and / or the decorative paper. Alternatively or additionally, the first resin is applied from below to the underside and / or the top side of the unprinted base paper and / or the decorative paper.

[0074] The unprinted base paper is preferably fed into the printing press before the design is applied. This is preferably done automatically. Preferably, the underside of the unprinted base paper faces upwards when it is fed into the printing press. Preferably, the printed design paper is then turned over after the design has been applied and before the stack of paper is assembled, so that the printed surface (top side) faces upwards. This turning can also take place within the printing press, so that the printed design paper exits the printing press with its printed side facing upwards. Alternatively, the surface to be printed (top side) of the unprinted base paper can face upwards when it is fed into the printing press.

[0075] Preferably, the top side of the unprinted base paper faces upwards during the printing of the design, so that the printed design paper does not need to be turned over after the design is printed and before the stack of compressed goods is assembled. The printed surface then preferably faces upwards after the design is printed. Alternatively, the underside of the unprinted base paper faces upwards during the printing of the design.

[0076] In one embodiment of the invention, the unprinted raw paper is turned over after the first resin has been applied and before the decorative layer has been printed. This turning preferably takes place after the first resin has dried or hardened. Preferably, after turning, the top side of the decorative layer faces upwards. In this way, the first resin can be applied from above to the underside, and the unprinted raw paper can be printed from above onto the surface to be printed. Alternatively, the unprinted raw paper is not turned over before the decorative layer is applied. Preferably, the unprinted raw paper and the decorative paper are not turned over before the stack of paper is compressed, and thus, in particular, not turned over during the entire process of finishing a wood-based panel.

[0077] A further development of the invention is characterized in that the applied first resin and / or the applied second resin is dried or cured under elevated temperature and / or pressure. Preferably, the drying or curing of the first resin and / or the second resin takes place at least partially, but preferably completely, before the stack of pressed material is assembled and / or the stack is compressed. Particularly preferably, the drying or curing of the first resin and / or the second resin takes place at least partially, but preferably completely, before the printing of the decoration, in order to prevent smearing of the resin. Alternatively, the drying or curing of the first resin and / or the second resin takes place at least partially, but particularly completely, after the printing of the decoration and / or after the stack of pressed material has been compressed.Preferably, in this case, the application of the first resin and / or the second resin also takes place after the printing of the decoration or the pressing of the stack of pressed material.

[0078] After the decoration is printed, the decorative paper is preferably dried (further) to dry the printing ink. Drying preferably takes place at an elevated temperature. Preferably, the first resin and / or the second resin has a degree of cross-linking of at most 80% after drying or curing, more preferably at most 60%, and particularly at most 40%. More preferably, the first resin and / or the second resin has a degree of cross-linking of at least 20%, and particularly at least 30%, after drying or curing. This ensures sufficient flexibility of the resin for further processing.

[0079] Preferably, the degree of cross-linking of the first resin and / or the second resin after pressing the stack of material is at least 80%, preferably at least 90%, and in particular at least 95%.

[0080] Preferably, the drying or curing of the first resin and the second resin takes place at least partially, but preferably completely, simultaneously. This reduces energy consumption and consequently also manufacturing costs.

[0081] Preferably, the unprinted base paper and / or the decorative paper has a residual moisture content of at most 20%, more preferably at most 10%, and particularly at most 6%, after drying or hardening. Preferably, the unprinted base paper and / or the decorative paper has a residual moisture content of at least 2%, more preferably at least 4%, and particularly at least 6%, after drying or hardening.

[0082] Preferably, the residual moisture content of the decorative paper after pressing the stack of material is at most 4%, preferably at most 2%, and in particular at most 1%.

[0083] The resins, in particular the first resin and / or the second resin, preferably have three states, namely a state A in which the resin is liquid and completely reactive, a state B in which the resin is dried, in particular partially cured, and still largely reactive, and a state C in which the resin is completely cured and thus essentially no longer reactive.

[0084] Preferably, the first resin and / or the second resin are in state B after drying or curing and before pressing the stack of material. Alternatively or additionally, the first resin and / or the second resin are in state A after application of the first resin and / or the second resin and before pressing the stack of material.

[0085] Preferably, the first resin and / or the second resin are in state C after the pressing of the stack of material.

[0086] A further development of the invention is characterized by the application of a primer to the surface to be printed prior to printing the design. This improves the color fidelity of the design. Preferably, the primer is dried before the design is printed. The primer preferably contains calcium chloride and / or methanol. The primer can be dried together with the first resin and / or the second resin, or separately. Preferably, the primer is applied to the unprinted paper after the first resin has been applied. Alternatively, it can also be applied before the first resin is applied to the unprinted paper and / or the printing paper. Preferably, the primer is applied at a rate of at least 2 g / m². 2, preferably at least 4 g / m² 2 , in particular at least 5 g / m² 2 applied to the surface to be printed. Preferably, the application rate of the primer to the surface to be printed is at most 20 g / m². 2 , preferably no more than 10 g / m² 2 , in particular a maximum of 6 g / m² 2 .

[0087] The printing system is preferably a digital printing system, more preferably a single-pass digital printing system. In such a single-pass digital printing system, the paper to be printed passes the printheads of the digital printing system only once. The printheads preferably extend across the entire printing width. The printing inks used are preferably cyan, red, yellow, and black (CRYK).

[0088] Preferably, the first resin and the second resin are identical. Alternatively, the first resin and the second resin are different.

[0089] After the design is printed, the decorative paper is placed on the top surface of the wood-based panel. Preferably, the decorative paper is placed on the wood-based panel so that the printed surface (top side) of the decorative paper faces upwards. The top surface of the wood-based panel is preferably sanded.

[0090] Preferably, the pressed material stack includes an overlay paper that is placed on the top side of the decorative paper laid on the wood-based panel. The advantage of this is that the overlay paper increases the strength of the pressed composite. Preferably, the overlay paper is placed on the top side of the decorative paper so that one side of the overlay paper faces upwards. Preferably, the overlay paper is at least partially, but preferably completely, transparent after the pressed material stack has been pressed. Advantageously, the overlay paper has a residual moisture content of at most 30%, preferably at most 20%, and particularly at most 10% when the pressed material stack is assembled. Preferably, the residual moisture content of the overlay paper when the pressed material stack is assembled is at least 2%, preferably at least 4%, and particularly at least 6%.

[0091] Preferably, the overlay paper is resin-coated. For example, the overlay paper can have an overlay resin coating on its top and / or bottom surface. Preferably, the overlay resin coating comprises or consists of the first resin and / or the second resin. Preferably, the unstuffed overlay paper has a coating weight of no more than 50 g / m². 2 , preferably no more than 40 g / m² 2 , preferably no more than 30 g / m² 2 , in particular a maximum of 20 g / m² 2 The overlay resin coating preferably has a basis weight of at least 10 g / m². 2 , preferably at least 30 g / m² 2 , in particular at least 50 g / m² 2 Preferably, the overlay resin coating has a basis weight of no more than 200 g / m². 2 , preferably no more than 150 g / m² 2 , in particular a maximum of 100 g / m² 2 , on.

[0092] The resin of the overlay resin application is preferably dried and is preferably in state B before pressing the stack of material. Preferably, the resin of the overlay resin application is in state C after pressing the stack of material.

[0093] Preferably, at least one protective layer is applied to the decorative paper and / or the overlay paper. Preferably, at least one protective layer is applied to the resin-impregnated overlay paper. This can, for example, improve abrasion resistance, walkability, and / or water resistance. The application of the at least one protective layer preferably takes place before pressing the stack of pressed material and / or before assembling the stack of pressed material.

[0094] Preferably, at least one protective layer comprises or consists of corundum. Preferably, corundum is applied at a rate of at least 5 g / m². 2, preferably at least 10 g / m² 2 , in particular at least 20 g / m² 2 , applied. Alternatively or additionally, at least one protective layer comprises or consists of glass beads, plastic beads, metal particles and / or pyrogenic silica.

[0095] Preferably, at least one protective layer and / or one resin layer, for example a resin layer formed by the first resin and / or the second resin, is imprinted with a structure during the pressing of the stack of pressed material, which corresponds to the decoration. For example, the structure can depict the course of edges, joints, grains, knots or pores in the decoration.

[0096] Preferably, the stack of pressed material comprises a backing paper on which the wood-based panel is placed. Such a backing paper can significantly reduce or completely compensate for any warping caused by pressing the stack of pressed material. In some embodiments, resin coating of the underside of the wood-based panel is not required, thus simplifying the overall finishing process. Preferably, the backing paper is resin-coated. For example, it can have a backing resin coating on its top and / or underside. Preferably, the backing resin coating comprises or consists of the first resin and / or the second resin.

[0097] Preferably, the unresin-free backing paper has a coating weight of no more than 50 g / m². 2 , preferably no more than 40 g / m² 2 , preferably no more than 30 g / m² 2 , in particular a maximum of 20 g / m² 2The counter-coating resin preferably has a basis weight of at least 10 g / m². 2 , preferably at least 30 g / m² 2 , in particular at least 50 g / m² 2 Preferably, the counter-coating resin has a basis weight of no more than 200 g / m². 2 , preferably no more than 150 g / m² 2 , in particular a maximum of 100 g / m² 2 , upset.

[0098] The resin of the counter-tension resin application is preferably dried and is preferably in state B before the pressing of the pressed material stack. Preferably, the resin of the counter-tension resin application is in state C after the pressing of the pressed material stack.

[0099] Preferably, the at least one resin of the resin-containing liquid is applied to the surface at least partially, but preferably completely, simultaneously with the primer and / or the at least one substance that improves the adhesion of ink applied during printing. Preferably, the at least one resin is mixed with the primer and / or the at least one substance that improves the adhesion of ink applied during printing before being applied to the surface.

[0100] Preferably, the wood-based panel is a particleboard or a fiberboard, in particular an HDF, MDF or OSB panel.

[0101] Advantageously, the wood-based panel is manufactured entirely before the printed paper is applied. Preferably, a raw mat containing wood chips and / or wood fibers is pressed under increased pressure and temperature before the printed paper is applied, thus creating the wood-based panel. The printed paper is then preferably applied to the top surface of this wood-based panel. In particular, the printed paper is thus applied to the top surface of a fully manufactured wood-based panel and not, for example, to an unpressed raw mat.

[0102] According to a second aspect, the invention solves the technical problem by a method for producing a decorative paper, wherein the method comprises the following steps:

[0103] Providing unprinted raw paper with a surface to be printed,

[0104] Printing a design onto the surface using a printing system to create decorative paper, the process being characterized by the following step:

[0105] Applying a first layer of resin to the unprinted raw paper and / or the decorative paper.

[0106] Advantageous embodiments of the method for producing decorative paper can be found in particular in the preceding descriptions of the method for finishing a wood-based panel. With the aid of the accompanying figure, which shows a schematic flowchart, some exemplary embodiments of the invention are explained in more detail below.

[0107] In a first step 2, an unprinted base paper with a surface to be printed is provided. In a second process step 4, a first resin in the form of a resin-containing liquid is applied to this base paper. In the illustrated embodiment, this includes a primer.

[0108] The decoration is printed onto this surface in printing step 8. Optionally, the paper can be laminated onto the wood-based panel before printing in printing step 8, but after the first resin has been applied in the resin-containing liquid. This takes place in lamination step 6. After printing step 8 and optional drying steps not shown, the press stack is formed in process step 10, which contains both the wood-based panel and the printed paper, which is then a decoration paper. This is independent of whether the decoration paper and the wood-based panel are still separate elements or whether the decoration was printed onto the paper laminated onto the wood-based panel.

[0109] The next step is pressing step 12, in which the stack of material to be pressed is compressed.

Claims

Flooring Technologies Ltd. Legal file: SmartCity Malta SCM01 , Office 406 2459-0777 PCT-1 Ricasoli, Kalkara SCM1001 Malta Date: December 18, 2025 Patent claims 1. A method for finishing a wood-based panel having a top surface, comprising the following steps: a. providing an unprinted raw paper with a surface to be printed, b. applying a resinous liquid to the surface so that the surface is impregnated with the resinous liquid, c. printing the resinous liquid-impregnated surface with a decoration using a digital printing system to produce a printed paper, d. forming a stack of pressed paper, placing the printed paper on the top surface of the wood-based panel, and e. pressing the stack of pressed paper under increased pressure and temperature.

2. Method according to claim 1, characterized in that the resinous liquid contains or consists of melamine resin and / or urea resin.

3. Method according to claim 1 or 2, characterized in that the resin-containing liquid contains a primer and / or at least one substance which improves the adhesion of ink applied during printing.

4. Method according to one of the preceding claims, characterized in that the resin-containing liquid is applied to the surface of the raw paper in such a way that the resin-containing liquid does not completely penetrate the raw paper, at least not completely.

5. Method according to one of the preceding claims, characterized in that the printed paper is impregnated with a synthetic resin or a synthetic resin mixture before being placed on the top surface of the wood-based panel.

6. Method according to one of the preceding claims, characterized in that at least one layer of a synthetic resin or a synthetic resin mixture is applied to the top surface of the wood-based panel before the printed paper is placed on the top surface.

7. Method according to one of the preceding claims, characterized in that the raw paper is dried in at least one dryer after the application of the resin-containing liquid and before printing with the decoration.

8. Method according to one of the preceding claims, characterized in that, when forming the press material stack, an overlay paper is placed on the printed paper placed on the top side of the wood-based panel.

9. Method according to one of the preceding claims, characterized in that less than 15 g / m³ 2 the resinous liquid is applied.

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