Covered panel and method for manufacturing a covered panel

Abstract

The invention relates to a coated panel and a method of manufacturing a coated panel. In particular, the invention relates to a coated panel having at least a substrate (2) and a top layer (3) applied thereon, wherein said top layer (3) comprises at least a decorative layer (4) and a semi-transparent or transparent wear layer (5), characterized in that said wear layer (5) comprises a thermally cured acrylate resin or a thermally cured unsaturated polyester resin. Preferably, wherein the thermal curing cures the resin partially or completely. In particular, wherein said acrylate resin or unsaturated polyester resin is at least partially cured by a thermal initiated free radical crosslinking reaction. The invention also relates to a method of producing such a coated panel (1), in particular a method of producing a floor panel.

Description

[0001] This application is a divisional application of the patent application with the application number 201980073813.4, the title "Covered panel and method of manufacturing a covered panel", and the filing date of 5 November 2019. TECHNICAL FIELD

[0002] The present invention relates to coated panels, in particular floor panels, and also to a method of manufacturing a floor panel.

[0003] More in particular, the present invention relates to a panel having a substrate and a top layer applied thereto, which has a decorative layer, for example comprising a printed decorative layer. Such floor panels are known per se, for example from WO 97 / 47834. The floor panel disclosed in said document in particular relates to a floor panel having a substrate which mainly consists of a HDF sheet on which a laminate layer is directly pressed, which laminate layer comprises one or more paper sheets impregnated with melamine resin, preferably also including a paper sheet printed with a pattern of e.g. wood or stone grains, in particular a so-called decorative paper. The above-mentioned melamine resin forms a semi-transparent wear layer on the decorative paper, among others, but the transparency or semi-transparency is far from perfect. On the bottom side of the substrate is a backing layer or balancing layer, also based on paper impregnated with melamine resin. This backing layer provides compensation for residual tensile stresses present in the cured melamine resin of the top layer. It is still possible to form very deep structures in the cured melamine surface. Frequently, so-called white mountains occur. These are areas of inclusions concentrated on the melamine surface. These mainly occur at locations where deep indentations or structures have been implemented. BACKGROUND

[0004] It is known that the melamine surface of such laminate panels produces a clicking sound in use. Various solutions to this problem are known from the prior art. WO 03 / 016655 discloses the application of a sound-deadening layer, for example a cork layer, under the melamine layer. From WO 2010 / 088769 and other documents it is known to provide the melamine layer with a coating of a flexible monomer. WO 2009 / 101217 and WO 2010 / 070474 give examples of laminate panels in which the top layer mainly consists of polyvinyl chloride (PVC) instead of melamine resin. WO 2010 / 070474 discloses a panel with a printed decorative layer which can be formed on a substrate and which is provided with a transparent PVC layer.

[0005] In addition, a method is known from WO 01 / 47726, which finishes the panel with a printed decor layer with UV (ultraviolet) or electron beam cured acrylate resin. This process is difficult to integrate into the existing production method of laminated panels and requires a complex material logistics, complex machines and leads to high costs. For example, electron beam curing requires an inert atmosphere, which makes it possible to process on board level and the technology is mainly applied to smaller panels or thin plates in physically closed lead space with the aim of eliminating the production of unhealthy gamma rays. These lead package assemblies have a thickness of more than 2.5 mm and are very heavy. The photoinitiators required for curing by UV radiation have a negative effect on the surface quality obtained. Molecules used as photoinitiators are under increasing pressure due to the health risks they pose to humans.

[0006] In panels where the top layer consists entirely of polyvinyl chloride (PVC), a decrease in scratch resistance is observed compared to traditional melamine surfaces. In addition, the PVC layer must be configured significantly thicker than the melamine layer in order to obtain comparable wear resistance. The properties and thickness of the PVC layer result in a plastic-like appearance of the floor panel, especially in the case of products intended to imitate, for example, wood, stone or ceramic. The relief that can be obtained in the PVC layer is not sharp, which detracts from the realistic appearance of the imitation obtained.

[0007] In panels where the top layer is obtained from UV or electron beam cured acrylate, for example in WO 01 / 47726, advantageous surface properties are obtained. The limitation of the relief that can be obtained in such a top layer is that a structured film must be applied, for example in EP2019735. SUMMARY

[0008] The present invention first aims to provide an alternative coated panel, in which a solution to one or more problems of the prior art panels is provided.

[0009] To this end, in a first independent aspect, the present invention relates to a coated panel, preferably a floor panel, a wall panel or a furniture panel, having at least a substrate and a top layer applied thereon, wherein the top layer comprises at least a decor layer and a semi-transparent or transparent wear layer, characterized in that the wear layer comprises a thermally cured acrylate resin and / or a thermally cured unsaturated polyester resin. Preferably, the resin is partially or completely cured in the thermal curing.

[0010] In the present document, a cured unsaturated polyester resin refers to a polyester resin that is unsaturated before curing and that can be cured by cross-linking the double bonds in the unsaturated polyester resin.

[0011] The use of a thermally cured acrylate resin and / or a thermally cured unsaturated polyester resin opens new possibilities for the design of wear layers, while retaining the excellent qualities of the wear layer of acrylate resin or unsaturated polyester resin. For example, the wear layer can thus be cured by hot pressing using structured compression elements. Surprisingly, the inventors found that the structure of the compression elements is very advantageously reproduced in the curing of the acrylate resin and / or the curing of the unsaturated polyester resin. In contrast to the curing reaction of melamine resin, in the curing reaction of acrylate resin and / or the curing of unsaturated polyester resin, there is no so-called chemical moisture or moisture that occurs as a reaction by-product, thus limiting the risk of inclusions in the translucent layer, even when working with deep structures, for example with a local depth greater than 400 pm, even 1 mm or more, relative to the entire surface.

[0012] Furthermore, the inventors found that the thermally cured acrylate resin and / or the thermally cured unsaturated polyester resin can have better transparency than the thermally cured melamine resin, for example the melamine resin available in the prior art laminate panels. The inventors attribute this to the strong curling of the polycondensed melamine resin. Thus, due to the brittleness of the melamine resin, the melamine resin in the cured state shows a large number of microcracks, which is not the case in the wear layer according to the application based on a thermally cured acrylate resin.

[0013] Furthermore, the inventors were able to determine that, in the case of the present application, the residual tensile stresses that can be present in the wear layer after curing are much lower than in the prior art laminate panels, whereby the risk of bending of the obtained panel or parts thereof can be greatly reduced, even when working without a backing layer.

[0014] The wear layer formed is softer than a melamine surface and has lower residual tensile stresses on the surface, so that this property can result in a more acceptable scratching sound, in particular a noise comparable to actual wood.

[0015] Moreover, in contrast to the case of UV-cured acrylate resins, thermal curing also allows a more homogeneous curing to be obtained. When curing takes place using UV radiation, the penetration depth of the light is limited. However, the thermal curing according to the application can be initiated by one or more thermal initiators that are uniformly or substantially uniformly mixed with the acrylate resin or the unsaturated polyester resin. In this way, the curing reaction can take place almost simultaneously and / or to the same extent over the entire thickness of the layer formed from the acrylate resin or the unsaturated polyester resin. In addition, thicker cured layers can be formed, for example layers with a thickness of between 50 and 1000 pm, more particularly between 60 and 300 pm, even more particularly between 100 and 300 pm.

[0016] If the above-mentioned acrylate resin or the above-mentioned unsaturated polyester resin is cured by at least a thermal initiated free radical crosslinking reaction, it is mainly indicated that the quality of the acrylate resin or the unsaturated polyester resin. The above-mentioned curing preferably comprises at least a crosslinking of the double carbon bonds present in the acrylate resin or the unsaturated polyester, for example can be the case in UV or electron beam cured acrylate resin or unsaturated polyester resin.

[0017] According to a particular possibility, the above-mentioned acrylate resin is cured by a thermal initiated free radical crosslinking reaction, in which the double carbon bonds present in the acrylate resin are crosslinked, and by a crosslinking reaction in which oligomers or monomers having hydroxyl (-OH) and / or amine (-NH2) and / or carboxyl (-COOH) functionality are crosslinked with isocyanates, aziridines, carbodiimides, etc. This crosslinking reaction is promoted by the temperature used during the first crosslinking reaction. According to one particular example, the acrylate resin comprises or consists of a polyurethane acrylate resin.

[0018] It is to be noted that the use of a curing agent, such as an isocyanate or an aziridine, in a UV curable coating is a double curing known per se to the inventors. This curing agent leads to a second internal crosslinking of the acrylate resin, in particular of the hydroxyl (-OH) and / or carboxyl (-COOH) and / or amine (-NH2) functional acrylate resin, which can only take place in an uncontrolled manner and possibly long after the previous UV curing. The above-mentioned particular possibility offers the possibility to provide a wear layer to a coating panel obtained by the application of a double curing system, in which the first crosslinking involves a thermal curing. By means of the thermal energy of the first crosslinking, the second crosslinking is initiated in a controlled manner and can be completed in a short time. In other words, this is an "instant double curing system".

[0019] According to a particular possibility, the curing of the acrylate resin or the unsaturated polyester resin is further promoted by a thermosetting promoter, such as for example by 2,4-pentanedione or N,N-diethylacetoacetamide, and / or a thermosetting accelerator, for example by a cobalt-free accelerator, for example by a copper or iron complex, or by cobalt octoate, amine diethyl aniline, dimethyl p-toluidine or ethoxylated p-toluidine.

[0020] It is clear that the presence of a thermal initiator in the acrylate resin or the unsaturated polyester resin used can play an important role in the quality and the relief of the resulting wear layer.

[0021] A thermal initiator can be more generally defined as a thermally unstable molecule which, upon exposure to heat, decomposes or disintegrates into at least one or more radicals. The radicals produced then play the same role as the radicals produced by the known photoinitiators in the UV curing of the acrylate resin. The thermally obtained radicals initiate the polymerization reaction of the double carbon bonds of the acrylate functions present in the acrylate resin.

[0022] For the same purposes as the first aspect, according to an independent second aspect, the present application relates to a coated panel having a substrate and a top layer applied thereon, wherein the top layer comprises at least a decorative layer and a semi-transparent or transparent wear layer, characterized in that the wear layer is obtained on the basis of a mixture of at least one aspect of an acrylate resin and / or an unsaturated polyester resin and another aspect of a thermal initiator. It is clear that the coated panel of the second aspect can show the features of the first aspect or preferred embodiments thereof. In particular, the mixture can further comprise a crosslinking agent, such as isocyanate, aziridine, carbodiimide, etc., so that the wear layer is obtained by means of the instant dual cure system mentioned in the context of the first aspect. In addition, the mixture can also comprise a thermosetting promoter and / or accelerator, such as those mentioned in the context of the first aspect of the present application.

[0023] Preferably, the thermal initiator is an organic peroxide, preferably benzoyl peroxide, methylbenzoyl peroxide, TBPIN (tert-butylperoxy-3,5,5-trimethylhexanoate) or lauryl peroxide. The inventors have found that these thermal initiators have a suitable minimum activation temperature, which is necessary to achieve decomposition into at least one or more radicals, so that a sufficiently cured wear layer can be obtained at an acceptable energy consumption, in particular at a suitable curing temperature. Of the above-mentioned peroxides, lauryl peroxide has the lowest activation temperature, so that curing of this resin can be completed quickly. However, in certain cases, for example in the event of the formation of relatively deep indentations in the wear layer, for example with a depth of 0.1 mm or more, or in the event that adhesion is to be obtained with an underlying layer comprising polyurethane, it is desirable that the resin remains flowable for a longer period of time. In such cases, it is preferred to use at least benzoyl peroxide or methylbenzoyl peroxide as thermal initiator. Of the latter initiators, methylbenzoyl peroxide is of greatest interest, since it produces the less toxic toluene as a reaction product, instead of benzene in the case of benzoyl peroxide. In this respect, it is also noted that the reaction with lauryl peroxide results in the formation of non-toxic aliphatic compounds.

[0024] Other examples of organic and inorganic peroxides suitable for use as thermal initiators are 2-butanone peroxide, persulfates, peroxodiphosphates and persulfates.

[0025] Other examples of peroxides that are also suitable for use as thermal initiators are ketone peroxides, diacyl peroxides, ketal peroxides, hydroperoxides, peroxydicarbonates, peroxy-monocarbonates, preferably tert-butylperoxy-3,5,5-trimethylhexanoate (TPBIN).

[0026] In addition to peroxides, as an alternative, azo polymerization initiators such as azonitriles, azo acid esters, hyponitrites and / or azo amides can also be used. As specific examples, azobisisobutyronitrile (AIBN), 2-methylbutyronitrile (AMBN), azopentanenitrile (AVN) can be used. Another option is to use cesium ions.

[0027] Of course, two or more of the above thermal initiators can be combined.

[0028] Preferably, the above mixture comprises 0.1 to 5 parts of thermal initiator per 100 parts of acrylate resin or per 100 parts of unsaturated polyester resin, and more preferably 0.5 to 2 parts of thermal initiator per 100 parts of acrylate resin or per 100 parts of unsaturated polyester resin, and more preferably 0.1 to 2 parts of thermal initiator per 100 parts of acrylate resin or per 100 parts of unsaturated polyester resin (a smaller amount of thermal initiator can be used to obtain a similar final curing if additional crosslinking is performed with UV light). By varying the concentration of the thermal initiator, the chain length of the obtained polymerized acrylate resin or polymerized unsaturated polyester resin can be adjusted. With a larger amount of thermal initiator, the reaction ends faster and a shorter chain length is obtained, while with a smaller amount, a longer chain length is obtained. With 0.5 to 2 parts of thermal initiator per 100 parts of acrylate resin or per 100 parts of unsaturated polyester resin, a balance between reaction rate and degree of crosslinking or chain length can be achieved. The time range to cure to half or to full cure is preferably such that sufficient resin flow can be obtained. Resin flow is important, for example, in the case of replicating the structure of a compaction element to the surface of a wear layer. This in particular requires displacement of the acrylate resin or unsaturated polyester resin into all the relief parts of the compaction element.

[0029] In the case of the above benzoyl peroxide, methylbenzoyl peroxide and / or lauryl peroxide, 0.5 to 2 parts per 100 parts of acrylate resin are used to obtain sufficient curing within an economically acceptable time range with acceptable energy consumption, while maintaining sufficient flow.

[0030] It is clear from the above that by choosing the thermal initiator and the concentration, the flow of the acrylate resin or unsaturated polyester can be adjusted. In the case of the acrylate resin, the flow can optionally be further extended by increasing the content of reactive diluent monomers or difunctional monomers (such as dipropylene glycol diacrylate (DPGDA)) in the acrylate resin. Preferably, the acrylate resin comprises 20 to 60 wt.% of monomers, preferably monofunctional and / or difunctional and / or trifunctional and / or tetrafunctional monomers.

[0031] In the following, preferred embodiments are discussed which can be applied in combination with the first, second, third and / or fourth aspect of the present invention.

[0032] Preferably, the wear layer of the coating panel of the first and / or second aspect comprises traces of peroxides, such as benzoyl peroxide, methylbenzoyl peroxide and / or lauryl peroxide.

[0033] Preferably, the wear layer comprises at least traces of reaction products resulting from the reaction of thermal initiators and acrylate resins. For example, the wear layer can comprise traces of benzene, toluene or aliphatic compounds.

[0034] Preferably, the wear layer described above is cured uniformly or substantially uniformly throughout its thickness.

[0035] Preferably, the thermal curing comprises chemical cross-linking - preferably double carbon bonds present in the acrylate resin - and / or double carbon bonds present in the unsaturated polyester resin. This cross-linking reaction results in very advantageous wear properties. By varying the initiator (thermal initiator and / or photoinitiator) concentration, and using a certain amount of UV light in the additional UV curing added to the lacquer base before the pressing process, the degree of polymerization and the type of polymerization can be controlled. While it is known that EB curing proceeds more uniformly through the matrix, it can be said that, when thermal curing is performed, in the case of a specified depth of texture and relief structure, there is a warm front which, over time, provides less uniform curing. This can affect the adhesion properties or chain length of the matrix.

[0036] Preferably, the wear layer described above is obtained on the basis of a mixture containing acrylate resin and / or unsaturated polyester resin on the one hand and photoinitiator on the other hand. More preferably, the mixture comprises 0.1 - 5 parts of photoinitiator per 100 parts of acrylate resin or per 100 parts of unsaturated polyester resin.

[0037] More preferably, the mixture comprises 0.1 - 5 parts of two different photoinitiators per 100 parts of acrylate resin or per 100 parts of unsaturated polyester resin. Preferably, the photoinitiators are chosen so that one photoinitiator cures the uppermost 20 pm of the wear layer (surface curing), and the other photoinitiator can cure the wear layer deeper (depth curing). This allows a more advantageous curing of the wear layer to be obtained.

[0038] Preferably, the above-mentioned decorative layer comprises a carrier sheet provided with a synthetic material, such as paper. For example, it can be a printed paper used for the production of DPL type laminate floor panels and / or a paper having a Gurley value of less than 30 seconds or even less than 25 or 20 seconds. A lower Gurley value is advantageous for providing the above-mentioned synthetic material into the paper core. Preferably, the paper has a surface weight of 40 to 250 grams per square meter, more preferably 55 to 150 grams per square meter, or 65 to 90 grams per square meter. A higher surface weight, in particular a surface weight of 90 to 150, is preferably used in furniture panels, whereas a lower surface weight, in particular 65 to 90 grams per square meter, is preferably applied in floor panels. The printing can be obtained in a similar way, for example by means of a flexographic printing process with a printing cylinder, and / or digitally, for example by means of an inkjet printing process, preferably in a so-called single pass printer.

[0039] Instead of paper with a synthetic material, it is also possible to use a film made of synthetic material, for example a film of PVC (polyvinyl chloride) or PET (polyethylene terephthalate) (whether or not printed), or a veneer, as a decorative layer. It is noted that a film made of synthetic material is an example of a moisture-impermeable layer, and the inventors have found that a thermally cured wear layer, in particular a thermally cured wear layer based on an acrylate resin, can be formed on a film or other impermeable layer formed of synthetic material, since no chemical moisture is generated during the curing of the acrylate resin. In the laminate layer of the prior art panels, the inventors assume that the chemical moisture migrates in the direction of the substrate, and in the prior art, an impermeable layer above this substrate is undesirable.

[0040] Preferably, the synthetic material provided on the carrier sheet is a synthetic material comprising double carbon bonds.

[0041] According to a particular embodiment, the synthetic material provided on the carrier sheet forms a part of the above-mentioned wear layer, wherein this part is located between the decorative layer itself (for example a printed pattern or a veneer) and the part of the wear layer formed of thermoset acrylate. The part of the wear layer formed of the synthetic material of the decorative layer can comprise hard particles, for example particles of aluminium oxide, silicon oxide or silicon carbide.

[0042] Preferably, the synthetic material provided on the carrier sheet is selected from the group consisting of amino resins, urea formaldehyde, melamine urea formaldehyde, melamine formaldehyde, polyurethane dispersions, urethane-acrylate copolymer dispersions, acrylates, latex, melamine acrylate, reactive acrylate monomers optionally combined with a crosslinker such as carbodiimide, polyisocyanate or aziridine. The synthetic material is preferably applied to the carrier sheet in the form of a water-based mixture or dispersion, for example by means of impregnation, one or more roll coating and / or one or more spraying or pouring. Such dispersions can be anionically, cationically or non-ionically stabilised. In case the carrier sheet comprises a digitally printed decorative layer, the dispersion is preferably cationically stabilised to prevent possible salts or acids in the optional inkjet receiver coating from destroying the stability of the polyurethane dispersion. It is of course not excluded that the above-mentioned synthetic material is a melamine formaldehyde. In such a case, for example, a coating promoting the bonding with a thermoset acrylate resin or a thermosetting polyester resin is applied on the surface of the carrier sheet provided with the synthetic material facing the wear layer. Such a coating can comprise an aliphatic polyurethane dispersion, a latex dispersion, a water-based UV-curable substance (for example a water-based UV-curable acrylate resin), a melamine acrylate, a chemically modified melamine resin or an etherified melamine resin. It is of course not excluded that the above-mentioned synthetic material is a thermoset acrylate resin or an unsaturated polyester resin. For example, in such a case, the use of a cationically stabilised polyurethane dispersion to form a coating on the printed paper and / or to impregnate the printed paper itself is an important finding. Then, according to one particular independent aspect, the present invention also relates to a method of producing a coated panel having a substrate and a decorative top layer with a printed paper, characterised in that the method comprises at least the step of providing a cationically stabilised polyurethane dispersion on a paper that has been printed or is to be printed. It is clear that the printing of such a paper is preferably carried out digitally and / or that such a paper comprises a previously applied coating with a pH of less than 7 (preferably 5 or less), for example an inkjet receiver coating. This particular aspect can of course show other preferred features, for example the features described earlier in this paragraph or the features described in the context of the other aspects of the present invention. The polyurethane dispersion used can also further show the following properties.

[0043] According to one important example, a polyurethane dispersion is applied to the carrier sheet. Preferably, a Konig hardness of the polyurethane coating obtained on the carrier sheet is in the range of 0.5 to 5.0 N / mm2, more preferably in the range of 1.0 to 3.0 N / mm2, even more preferably in the range of 1.5 to 2.5 N / mm2. The polyurethane coating of the present embodiment can also be located in the core of the carrier sheet. According to another important possibility, the core of the carrier sheet is impregnated with a polycondensation resin (such as a melamine-based resin), while the polyurethane coating is present mainly at the surface of the carrier sheet. This possibility provides good crack resistance in an economic manner on the carrier sheet, while retaining the advantages of the polyurethane coating, such as reduced click or other sounds. Preferably, the polyurethane coating exhibits an elongation of 40% to 400%, 100% to 300%, preferably 120% to 250%. The high elongation provides a bridge between the decorative paper (which, as mentioned above, can optionally use a polycondensation, for example based on melamine, to provide in the core) and the thermally cured acrylic resin. Preferably, the acrylic resin mentioned above is obtained based on multifunctional acrylic or methacrylic monomers and / or oligomers (such as hexafunctional acrylic or methacrylic oligomers). The multifunctional acrylic or methacrylic oligomers can provide a hard layer, but this layer should be as brittle and wear-resistant as possible.

[0044] According to the important example mentioned above, the polyurethane dispersion having a weight of 5 to 60 g dry substance per square meter and preferably 10 to 20 g dry substance per square meter is preferably applied to the carrier sheet.

[0045] Preferably, the polyurethane dispersion applied according to the important example mentioned above is water-based and contains acrylic ester functions, and / or the dispersion contains UV acrylic ester, such as an epoxy-modified polyurethane acrylic ester, such as the commercially available NeoRad UV2040W. With this preferred embodiment, improved adhesion can be achieved using a thermally cured acrylic resin. To facilitate film formation of the PU dispersion, 1 to 10% by weight, preferably 2 to 6% by weight, of a solvent is preferably used in the dispersion. For example, DPnB (dipropylene glycol n-butyl ether), DPM (dipropylene glycol methyl ether); PM (propylene glycol methyl ether), 2-butoxyethanol or diethylene glycol can be used.

[0046] Preferably, the PU dispersion exhibits an MFFT (minimum film formation temperature, ISO 2115) of 0 to 40°C, 6 to 20°C and preferably 5 to 15°C.

[0047] A reactive 100% acrylate primer can be used. This primer can penetrate the melamine layer and can covalently bond with the transparent top layer applied subsequently. Such an acrylate primer can for example consist of HDDA (1,6-hexanediol diacrylate), ACMO (acryloylmorpholine), melamine acrylate or an acidic adhesive acrylate.

[0048] Preferably, the acrylate resin described above is obtained based on at least monofunctional or difunctional acrylate or methacrylate monomers and / or oligomers. Difunctional acrylate or methacrylate oligomers can result in a tough or less brittle wear layer. Also trifunctional and / or tetrafunctional acrylates can be used.

[0049] Preferably, acrylate monomers or oligomers can be used, as they are more reactive than methacrylate monomers or oligomers.

[0050] Preferably, the acrylate resin described above is of the aliphatic type. With such an acrylate resin, aging and / or discoloration can be limited to the greatest extent.

[0051] Preferably, the acrylate resin comprises 5 to 80 wt.% of monomers, or more preferably 5 to 60 wt.%, which can be monofunctional, difunctional or multifunctional monomers. The monomers in the acrylate resin can have one or more of the following effects: increasing the viscosity to the desired value, improving the adhesion by better absorption in the adjacent layer (e.g. substrate), or positively or negatively influencing the reactivity in the decorative layer, significantly influencing the flexibility and / or brittleness of the resulting wear layer, for example setting the operating range in terms of the temperatures used, and positively influencing the chemical resistance. For example, with the use of multifunctional monomers, better crosslinking, curing and chemical resistance can be achieved. For this purpose, for example, trifunctional monomers such as TMPTA can be used. For difunctional monomers, in view of the short chain length, promoting crosslinking and curing can also be achieved. For example, DPGDA (dipropylene glycol diacrylate) monomers can be used, which result in sufficient flow during solidification.

[0052] According to the most preferred embodiment, the acrylate resin described above is obtained based on a mixture of at least two or more acrylate oligomers of different functionality, preferably based on a mixture of a multifunctional acrylate oligomer and a difunctional acrylate oligomer, wherein "multifunctional" is understood to mean more than two. With such a mixture, the desired hardness and toughness of the final wear layer can be set.

[0053] The use of an acrylate resin as a wear layer also makes it possible to mix acrylates with specific properties. For example, the acrylate resin described above can be obtained with at least a chemically modified acrylate, such as a fluoroacrylate. By adding a chemically modified acrylate to the acrylate resin, properties such as hydrophobicity, easy maintenance, anti-fingerprint properties and antibacterial properties can be obtained. Other possible additives to the acrylate resin are metallic pigments and materials that improve the haptic interaction. The additives mentioned here have no or substantially no influence on the thermal curing of the acrylic resin.

[0054] Preferably, at least hard particles, such as aluminium oxide particles, silicon oxide or silicon carbide particles, are added to the acrylate resin or the unsaturated polyester resin. According to an alternative, the hard particles described above are located between the decorative layer and the part of the wear layer formed by the acrylate resin and / or the thermally cured unsaturated polyester resin. In the case of a decorative layer comprising a carrier sheet provided with a synthetic material, the hard particles described above can be located in the layer formed by this synthetic material. Preferably, at least 5 grams or at least 10 grams of such hard particles are added per square metre. Such particles can further increase the wear resistance. Preferably, the particles have a so-called mesh size of F100 or less, but preferably not less than a mesh size of F320. The latter approximately corresponds to an average particle size of 30 to 125 pm. Whether or not in combination with the hard particles present, the wear resistance of the wear layer obtained can be adjusted by its thickness. Preferably, the thickness of the wear layer obtained on the basis of a thermally cured acrylate resin is at least 50 pm, and preferably at least 100 pm.

[0055] Preferably, the wear layer described above is obtained with 10 to 300 grams per square metre of the acrylate resin described above or the unsaturated polyester resin described above. In the case of a furniture panel, the wear layer is preferably obtained with 10 to 80 grams (dry solids) and preferably 10 to 30 grams (dry solids) of acrylate resin or thermally cured unsaturated polyester resin per square metre, while in the case of a floor panel, the wear layer is preferably obtained with 30 to 160 grams of acrylate resin or unsaturated polyester resin per square metre.

[0056] Preferably, in any embodiment of the coated panel according to any aspect of the application, the wear layer consists of different layers. The wear layer comprises a plurality of layers having the features of the embodiments of the wear layer described as the first and / or second and / or fourth aspect of the application, and / or obtainable by any embodiment of the method of the third aspect of the application.

[0057] The thermally cured acrylate resin or the unsaturated polyester resin can be applied in the wear layer in a plurality of layers, and the chemical formulation of these layers can be the same, but they can also differ from each other to optimise the relationship between performance and cost or to optimise the flow behaviour in the press.

[0058] Preferably, the compositions of the multiple layers differ from each other. More preferably, the uppermost layer of the wear layer comprises one or more of a fluorinated acrylate, micro alumina, silicone acrylate or nano silica.

[0059] Preferably, the coated panel according to any of the independent aspects of the present application is a floor panel, preferably suitable for floating installation. The wear layer can exhibit a particularly high wear and / or scratch resistance, but it is also soft enough to significantly improve the noise compared to conventional melamine surfaces.

[0060] Preferably, the coated panel has a relief on its surface. Preferably, the relief also shows gloss differences. These gloss differences can occur in areas with at least two respective glosses, wherein these glosses can be clearly distinguished by the user and thus by the naked eye. More specifically, it is preferred that at least two glosses are used for the above-mentioned areas to be selected respectively, so that the designated areas clearly appear as matte areas, while the other areas appear as non-matte or glossy areas. The gloss of the majority of the matte areas on the coated panel, for example a floor panel, is preferably 10 or more preferably less than 10, while the gloss of the less matte or glossy areas is greater than 10 and more preferably greater than 20, all measured according to DIN 67530. Regardless of the absolute gloss used, the gloss difference between the matte and glossy areas of the coated panel is preferably at least 10.

[0061] For the same purposes as the first and second aspects, according to an independent third aspect, the present application also relates to a method for producing a coated panel, wherein the panel comprises at least a substrate and a top layer applied thereon and the above-mentioned top layer comprises at least a decorative layer and a semi-transparent or transparent wear layer, characterized in that the method comprises at least the following steps:

[0062] - a step of applying to the above-mentioned decorative layer one or a combination of an acrylate resin, an unsaturated polyester resin, a coating composition comprising an acrylate resin; wherein the acrylate resin, the unsaturated polyester resin or the coating composition optionally comprises a thermal initiator and optionally a photoinitiator; and

[0063] - a step of at least partially curing the above-mentioned acrylate resin or unsaturated polyester resin or coating composition by hot pressing to form at least part of the above-mentioned wear layer. It goes without saying that for the acrylate resin, unsaturated polyester resin or coating composition and the optional thermal initiator, the possibilities mentioned in the context of the above-mentioned first and / or second aspect of the application can be relied upon. Preferably, the coating composition or the acrylate resin comprises at least a multifunctional acrylate oligomer and 0.5 to 2 parts per 100 parts of acrylate resin of benzoyl peroxide, methylbenzoyl peroxide or lauryl peroxide as thermal initiator; and more advantageously 0.1 to 2 parts per 100 parts of benzoyl peroxide, methylbenzoyl peroxide or lauryl peroxide as thermal initiator, and more advantageously 0.1 to 1 parts per 100 parts of benzoyl peroxide, methylbenzoyl peroxide or lauryl peroxide as thermal initiator. By curing under pressure, the possibilities of the thermally cured acrylate resin or thermally cured unsaturated polyester resin are exploited to the maximum. It is clear that in this case too, the above-mentioned instant dual cure system can be applied, in which a lower amount of thermal initiator can be used.

[0064] In the use of an acrylate resin (whether or not it forms the above-mentioned coating composition) or unsaturated polyester resin, it is preferable to use an acrylate resin or unsaturated polyester resin comprising oligomers and monomers.

[0065] Preferably, in the method according to the third aspect of the application, hard particles such as aluminium oxide particles, silicon oxide particles or silicon carbide particles are added to the acrylate resin or unsaturated polyester resin or coating composition.

[0066] Preferably, the above-mentioned pressing is carried out by means of a so-called short cycle press or single-daylight press. Of course, it is not excluded that a continuous press can be used, preferably a press with moving press belts between which the entirety to be pressed moves, or hot press rollers. A continuous press can also be used which makes use of one or more press cylinders which are preferably textured. The application is particularly important in the texturing of the wear layer by means of extrusion cylinders (in texturing, the top layer of the coated panel is provided with a relief). In this technique, the residence time under pressure is particularly short, and even within such a short residence time, the fast thermally cured acrylate resin or fast thermally cured polyester resin can sufficiently take up the structure of the pressing elements. In this process, the top layer of the coated panel is provided with a relief, including an accurate reproduction of different glosses.

[0067] Preferably, the above-mentioned pressing is carried out at a temperature of 70 to 220°C, preferably at a temperature of 120 to 220°C, and / or at a pressure of 5 to 80 bar. The inventors have obtained advantageous results in a short cycle press at 195°C and 40 bar (about 40 kg / cm 2 ) for 22 seconds. Such process parameters correspond to those used in the pressing of melamine-based laminate panels. However, such high temperatures and pressures are not necessarily essential in the pressing of thermally cured acrylate resins or thermally cured unsaturated polyester resins, and the process parameters can be adjusted within a larger range, more particularly can be reduced until the desired efficacy is achieved.

[0068] As mentioned above, in the case of the use of structured pressing elements, the thermally cured acrylate resin (including the acrylate resin in the coating composition) or the thermally cured unsaturated polyester resin preferably shows sufficient flow. For this purpose, it is preferred to use at least benzoyl peroxide or methylbenzoyl peroxide as initiator.

[0069] The inventors have found that it can be important to increase the pressing pressure quickly, in order to carry out the deformation caused by the pressing element before the curing of the acrylate resin takes place in nature, so that the desired structure is formed in the surface and / or the substrate of the panel. This is also important in the case of a wear layer of thermally cured acrylate resin to be adhered to an underlying layer, for example containing polyurethane, such as to a carrier sheet or a decor paper treated on the surface using a polyurethane dispersion as described above.

[0070] Preferably, the above-mentioned pressing is carried out with the aid of structured pressing elements, for example of the type known per se from WO 2009 / 043910, such as structured pressing plates.

[0071] At the pressing, a so-called frame or frame is used in the pressing, which extends along all edges of the material to be pressed. The purpose of such a frame or frame is to optionally hinder the splashing of the acrylate resin or the unsaturated polyester resin from the press when the pressure is increased. Furthermore, the thickness of the frame or frame is chosen such that the exact desired thickness of the wear layer can be provided. In addition, the frame or frame ensures that sufficient pressure is applied to the cured acrylate resin or the cured unsaturated polyester resin.

[0072] According to a particular embodiment, the method of the present application further comprises the step of post-curing the pressed wear layer by means of ultraviolet and / or electron radiation, both preferably under inert atmosphere. According to one important example of this particular embodiment, a surface can be achieved which has comparable relief and / or gloss differences to those achievable with melamine surfaces, but with the quality and noise characteristics of an electron beam cured surface. For this purpose, the wear layer pressed and structured by means of pressing elements can be post-cured by means of electron radiation under inert atmosphere.

[0073] Preferably, the above pressing is performed on a stack comprising at least a substrate, a decorative layer and an acrylate resin, an unsaturated polyester resin or a coating composition. In this way, a method is realized which corresponds to the process in many respects to the production process of a laminate panel, so that the method can be simply incorporated into existing laminate production.

[0074] Preferably, the step of applying an acrylate resin or an unsaturated polyester resin or a coating composition to the above decorative layer is performed when the decorative layer is already part of a stack comprising at least a substrate and a decorative layer.

[0075] Preferably, as mentioned above, the above decorative layer comprises a carrier sheet, such as paper, and in such case the method further preferably comprises at least providing a synthetic material to such carrier sheet. The method can further comprise the step of providing a hard particle, such as a particle of aluminium oxide, silicon oxide or silicon carbide, to the above synthetic material. This step can be performed in practice in various ways, such as mixing the hard particle into the synthetic material before providing the synthetic material to the carrier sheet, or applying the hard particle to the synthetic material after the synthetic material has been provided to the carrier sheet, such as by spreading the particles or by applying a flowable mixture or dispersion comprising the particles by roll coating, spray coating or jetting.

[0076] Preferably, the step of providing a synthetic material to the carrier sheet comprises at least applying a water-based or aqueous UV-curable synthetic material to the above carrier sheet.

[0077] Preferably, the step of providing a synthetic material to the carrier sheet comprises at least applying a UV-curable substance, such as an acrylate resin and / or an unsaturated polyester, wherein such substance further comprises a thermal initiator. This can be a so-called hydro-UV or all-hydro system, which comprises a thermal initiator. Solvent-borne acrylates can also be used; these form a non-sticky film after drying. Such a system can comprise relatively long oligomers. The treated carrier sheet can be dried to a non-sticky state. Final curing of the oligomers can then be performed in the pressing.

[0078] As mentioned above, the synthetic material provided on the carrier sheet preferably further comprises a hard particle, such as a corundum particle, for example an aluminium oxide particle.

[0079] It should be noted that the step of applying the acrylate resin or unsaturated polyester resin or coating composition to the aforementioned decorative layer can be performed in two or more sub-steps. Such an embodiment makes it possible to apply larger amounts of the aforementioned acrylate resin or the aforementioned unsaturated polyester resin or coating composition in a more uniform manner. Furthermore, acrylate resins or unsaturated polyester resins or coating compositions of different composition can be applied in the respective sub-steps. For example, only the acrylate resin layer closest to the surface of the panel or to be formed as the surface of the panel can be added with acrylates having a specific functionality, such as acrylates providing a higher degree of clarity, or only the specified layer can be added with hard particles, such as aluminum oxide.

[0080] In addition, it should be noted that when the coating composition, acrylate resin or unsaturated polyester resin comprises a photoinitiator, such a coating composition, acrylate resin or unsaturated polyester resin can be gelled before pressing and / or after pressing before post-curing by UV radiation in the presence or absence of an inert atmosphere to counteract oxygen inhibition. In the case of the aforementioned possibility, in which the coating composition, acrylate resin or unsaturated polyester resin is applied in two or more sub-steps, any UV radiation before pressing does not necessarily have to be performed on all partial layers. For example, it is useful at least not to gel the uppermost partial layer in order to preserve the sufficient flow of the coating composition, acrylate resin or unsaturated polyester resin in the pressing for the production of indentations in this layer by a texturing pressing element in such a way that in the deepest point of such an indentation there is still a thermally cured coating composition, a thermally cured acrylate resin or a cured unsaturated polyester resin, and / or for the production of gloss differences in this layer by a pressing element having gloss differences.

[0081] The use of photoinitiators and UV radiation before pressing results in a surface to be pressed which is dry or at least to some extent dry for the pressing. For various reasons in the production process, for example in order to facilitate intermediate storage and / or stacking, it can be necessary to carry out a dry process. Such a dry or semi-dry state can also be achieved in other ways. Several important possibilities are listed below.

[0082] Preferably, the coating composition used in the method used comprises at least an acrylate resin, one or more components comprising free hydroxyl groups, one or more components comprising free isocyanate groups, optionally one or more thermal initiators, optionally a photoinitiator, and optionally one or more crosslinking agents. The thermal initiators, photoinitiators and crosslinking agents mentioned in other aspects of the application can be used. In addition, the coating composition can comprise hard particles in the manner and as described in the other independent aspects of the application.

[0083] Preferably, the coating composition comprises a hydroxyl-functional acrylate and / or a hydroxyl-functional urethane acrylate.

[0084] Preferably, the coating composition comprises an isocyanate polymer and / or an isocyanate-functional acrylate.

[0085] Preferably, in the above hot pressing of the method, a condensation reaction between the hydroxyl groups and the isocyanate groups of the coating composition takes place, thereby creating cross-linking in the coating composition.

[0086] Preferably, the method comprises the step of removing water and / or solvent from the coating composition, acrylate resin or unsaturated polyester resin after the step of applying the coating composition, acrylate resin or unsaturated polyester resin to the above decorative layer; and before the step of at least partially curing the above coating composition, acrylate resin or unsaturated polyester resin by hot pressing to form at least part of the above wear layer.

[0087] Preferably, the method comprises the step of gelling the coating composition, acrylate resin or unsaturated polyester resin into a non-tacky state after the step of applying the coating composition, acrylate resin or unsaturated polyester resin to the above decorative layer; and before the step of at least partially curing the above coating composition, acrylate resin or unsaturated polyester resin by hot pressing to form at least part of the above wear layer. This embodiment has the advantage that a non-tacky intermediate product can be obtained, for example in a rolled-up state, before hot pressing takes place.

[0088] Preferably, the method comprises the step of UV post-curing the pressed wear layer after hot pressing, wherein cross-linking of the double bonds takes place. To this end, the coating composition, acrylate resin or unsaturated polyester resin preferably comprises a photoinitiator. This UV-curing is preferably carried out under an inert atmosphere.

[0089] Preferably, the method comprises the step of thermal post-curing the pressed wear layer after hot pressing, wherein cross-linking of the double bonds takes place. To this end, the coating composition, acrylate resin or unsaturated polyester resin preferably comprises a thermal initiator. Preferably, the thermal post-curing after hot pressing is carried out at a temperature higher than the temperature of the hot pressing.

[0090] In a preferred embodiment of the method, prior to the step of applying the coating composition, acrylate resin or unsaturated polyester resin or a combination thereof to the aforementioned decorative layer; the method comprises the step of applying an adhesion promoter to the aforementioned decorative layer. Preferably, the adhesion promoter comprises or consists of one or more of a polyurethane, a polyurethane dispersion, a water-based polyurethane dispersion, a polyurethane dispersion with acrylate functionality, a melamine acrylate or an acrylate primer. More preferably, a reactive low viscosity acrylate primer is used. Adhesion promoters such as those described in the first and / or second aspect of the application can be used in the method of the third aspect of the application.

[0091] Preferably, the application of the coating composition, acrylate resin or unsaturated polyester resin or a combination thereof to the aforementioned decorative layer is performed by wet or dry lamination.

[0092] When a coating composition is used in the method, this coating composition preferably comprises a solvent, such as butyl acetate. The use of a coating composition comprising a solvent has many advantages. If the coating composition is applied to a thermoplastic decorative layer, this solvent acts on this thermoplastic decorative layer. In this way, after curing of the wear layer, a better adhesion to the decorative layer is obtained. Examples are the use of a decorative layer comprising a thermoplastic film, such as polyvinyl chloride (PVC); and more preferably a printed thermoplastic film, more preferably a printed thermoplastic polyvinyl chloride (PVC) film. Examples are decorative layers formed by pressing thermoplastic substrates, wherein these thermoplastic substrates can comprise fillers, such as wood fibers, or inorganic fillers, such as calcium, clay or chalk. Such thermoplastic substrates can comprise polyvinyl chloride (PVC) or polyethylene or polypropylene as thermoplastic plastic.

[0093] In a preferred method wherein pressing is performed by a continuous press or by a hot press roller, the method preferably comprises the step of applying the decorative layer to the substrate by unwinding the decorative layer from a roller, and this decorative layer is preferably a film made of synthetic material or a printed film made of synthetic material or a printed paper - and preferably impregnated with a thermosetting resin. More preferably, the coating composition is placed on the decorative layer by dry lamination via unwinding from a roller.

[0094] Preferably, the embossing is pressed into the wear layer after the hot pressing and, after pressing the embossing, the wear layer is post-cured by heat or by UV radiation. Such embodiments allow to achieve high quality decorative effects. The wear layer is partially heat-cured during the hot pressing. However, the wear layer still shows sufficient plastic properties to allow the pressing of the embossing into it in a subsequent process, whether or not in a hot state. Due to the plastic behavior of the wear layer, this can be done in the form of a press embossing and without any cracks in the wear layer. In a subsequent post-curing, for example by heat or by UV radiation, the wear layer is further cured, thereby giving it the final properties. In such post-curing, the use of UV radiation is preferred, as this also makes an efficient curing of deep and narrow layer embossings possible. For example, this method also makes it possible to produce panels with a top layer that realistically simulates wood, by pressing embossings into the decorative layer that are aligned with the printed wood pattern. By the present invention, this is also possible when using thermoplastic substrates, such as substrates comprising polypropylene, polyethylene, polyvinyl chloride, whether or not they have fillers such as wood fibers or wood particles or inorganic fillers, for example calcium, clay or chalk.

[0095] In a preferred method, the substrate comprises a thermoplastic, preferably PVC, polypropylene or polyethylene. Preferably, this thermoplastic is filled with fillers. The decorative layer comprises a film made of synthetic material, for example a polyvinyl chloride film, and more preferably this film made of synthetic material is printed. Alternatively, the decorative layer can comprise or consist of a print on the substrate.

[0096] In a preferred method, the substrate comprises or consists of a wood fiber board, such as MDF or HDF; and the decorative layer comprises a printed carrier sheet, preferably a printed paper. The carrier sheet is preferably impregnated with a thermally cured resin.

[0097] In addition, the method can also be carried out according to the various possibilities discussed below. When an acrylate resin is specified, these possibilities also apply to the use of a coating composition comprising an acrylate resin.

[0098] According to a first possibility, the acrylate resin or the unsaturated polyester resin or the coating composition is applied by means of a two-component varnish. Such a two-component varnish can be dried by physical curing, while the heat-curing acrylate component or the heat-curing unsaturated polyester component is cured in the hot pressing.

[0099] According to a second possibility, in the acrylic or unsaturated polyester resin, two thermal initiators with different SADT (self-accelerating decomposition temperature) are applied. The lowest SADT is preferably chosen so that it is lower than the pressing temperature and this thermal initiator can thus act before the pressing or before the activation of the other thermal initiator. Upon activation of the thermal initiator with the lowest SADT, some drying can be obtained.

[0100] According to a third possibility, the acrylic resin is applied as 100% solid matter with a photoinitiator and a thermal initiator. The acrylic resin can then be gelled by UV radiation, so that some drying is obtained. The coated paper can then optionally be stored at a temperature below the SADT of the thermal initiator. Further or complete curing is then achieved in hot pressing. After pressing, further curing by UV radiation can be chosen.

[0101] According to a fourth possibility, a water electro or water based varnish with both a photoinitiator and a thermal initiator is used. The work can be done in the same way as the third possibility, further curing after pressing can similarly be chosen.

[0102] According to a fifth possibility, a solvent based acrylic or unsaturated polyester resin containing a thermal initiator and / or a photoinitiator is used. After application of the solvent based resin, the solvent is evaporated at low temperature. A tack-free surface is then obtained. Curing is done after pressing the panels, preferably with additional curing by UV radiation after pressing.

[0103] According to a sixth possibility, a dual-cure varnish is used, in which a combination of hydroxy-functional acrylic esters is combined with isocyanate-functional acrylic esters. This varnish contains a photoinitiator and / or a thermal initiator. After solvent evaporation, the varnish is not tacky and curing is achieved by crosslinking of the hydroxy groups with the isocyanate groups and concomitant curing through the double carbon bonds.

[0104] According to a seventh possibility, a water electro or water based varnish can be used, mainly with only a thermal initiator to initiate the radical reaction. The acrylic resin can then be gelled by hot air or (N)IR radiation. The coated paper can then optionally be stored at a temperature below the SDAT of the thermal initiator. Further or complete curing is then achieved in hot pressing. After pressing, further curing by UV radiation can be chosen if a photoinitiator is present.

[0105] According to a further possibility, the various possibilities among those described above can be combined in different partial layers, optionally with intermediate concomitant drying or gelling or partial curing.

[0106] Typically, in the context of the present invention, it is preferred that the above-mentioned thermally cured acrylate resin layer or thermally cured unsaturated polyester covers the entire surface of the floor panel, optionally excluding a reduced edge area, for example in the form of a bevel or so-called chamfered edge. In this way, the entire surface is given sufficient water resistance.

[0107] For the same purpose as the first to third aspects, according to an independent fourth aspect, the present invention also relates to a coated panel having at least a substrate and a top layer applied thereto, wherein the above-mentioned top layer comprises at least a decorative layer and a translucent or transparent wear layer, characterized in that the above-mentioned wear layer comprises an acrylate, wherein this acrylate comprises covalent bonds formed by the reaction of hydroxyl groups with isocyanate groups. The coated panel according to the fourth aspect of the present invention can be made by the method according to the third aspect of the present invention, wherein an acrylate resin or a coating composition comprising an acrylate resin is used.

[0108] The coated panel according to the fourth aspect of the present invention, the adhesion promoter is located between the decorative layer and the wear layer. Preferably, the adhesion promoter comprises or consists of one or more of a polyurethane, a polyurethane dispersion, a water-based polyurethane dispersion, a polyurethane dispersion with acrylate functionality, a melamine acrylate or an acrylate primer, for example a reactive low viscosity acrylate primer. In this case, the adhesion promoters mentioned in the other aspects of the present invention can be applied.

[0109] The coated panel according to the fourth aspect of the present invention preferably comprises a relief in the wear layer. More preferably, the relief shows a gloss difference.

[0110] Preferably, the coated panel according to the fourth aspect of the present invention has a decorative layer showing a wood pattern by printing, and the wear layer comprises a relief aligned with the wood pattern, and the relief more preferably comprises a gloss difference aligned with the wood pattern.

[0111] Preferably, the coated panel according to the fourth aspect of the present invention comprises a substrate comprising a thermoplastic, for example polyvinyl chloride, polyethylene or polypropylene. Preferably, this thermoplastic comprises one or more fillers, for example wood fibers or inorganic fillers, for example calcium, clay or chalk. The decorative layer comprises a film made of synthetic material or a printed film made of synthetic material, or the decorative layer comprises a print on the substrate.

[0112] Preferably, the coated panel according to the fourth aspect of the present invention comprises a substrate comprising or consisting of a wood fiber board, such as MDF or HDF. The decorative layer comprises a printed carrier sheet, preferably a printed paper, and preferably a printed paper impregnated with a thermally cured resin.

[0113] It is clear that the method of the third aspect is preferably used for producing the coated panel of the first and / or second aspect and / or the fourth aspect and / or the preferred embodiments thereof.

[0114] It is clear that the coated panel of the first, second or fourth aspect and / or obtained according to the third aspect can show different structures. The following lists a number of important possibilities, but this list is not intended to be exhaustive.

[0115] According to a first possibility, the coated panel comprises a wood fiber board as a substrate, a printed paper provided with synthetic material as a decorative layer and the wear resistant layer of the present invention. According to an important example, the printed paper comprises a polyurethane coating at least on the surface facing the wear resistant layer. Preferably, the paper in the core is impregnated with a melamine based resin, such as a modified melamine resin. The polyurethane coating preferably has a König hardness of 50 to 70 seconds. The wear resistant layer preferably shows traces of benzene or toluene, or benzoyl peroxide or methylbenzoyl peroxide. Preferably, hard particles, such as corundum particles, are located on the printed paper. Preferably, the coated panel shows a structure or a relief in its surface, more specifically in the wear resistant layer, which structure or relief has a cross section of 400 pm depth or more and / or a relief cross section penetrating into the substrate.

[0116] According to a second possibility, the coated panel comprises a substrate consisting of synthetic material or synthetic composite material, more specifically a thermoplastic or a thermoplastic composite material. This can for example be a substrate based on filled PVC (polyvinyl chloride), PP (polypropylene), PET (polyethylene terephthalate), PU (polyurethane). The filler can comprise calcium carbonate or talc or another powder or substance, such as wood chips, bamboo chips and / or other plant components. In the case of PVC, it can be rigid, semi-rigid or flexible PVC, specifically with a plasticizer content of less than 5, 5 to 15, or more than 15 per 100 parts of PVC, respectively. The filler content can vary sharply and can be up to 80 or 85 wt% of the composite material. The decorative layer can for example comprise a print arranged on a film made of synthetic material, such as on a PVC film. Then, according to the present invention, the wear resistant layer comprises at least a portion obtained on the basis of a heat-cured acrylate or a heat-cured unsaturated polyester. It is clear that the wear resistant layer can also comprise other portions, such as a transparent film made of synthetic material, for example a transparent PVC film, which is then located below the portion formed from the heat-cured acrylate or the heat-cured unsaturated polyester. This embodiment allows to provide clear relief properties and excellent surface properties on the surface of a panel consisting mainly of thermoplastic.

[0117] According to a third possibility, the coated panel comprises a substrate which is at least partially cured together with a part of the wear layer formed from a coating composition or an acrylate resin or an unsaturated polyester resin and preferably also a decorative layer. The substrate can for example be formed on the basis of a textile layer, a woven layer or a non-woven layer (for example a so-called spun-bond non-woven layer), such as on the basis of a textile layer preferably provided with a thermosetting synthetic material such as a thermosetting acrylate resin or a thermosetting unsaturated polyester, for example glass fibres, steel fibres, etc. The stack of the textile layer provided with the synthetic material, the decorative layer and the wear layer can be pressed in a hot press to form the coated panel of this third possibility in one step. In this way, a very thin but stable panel can be obtained, such as a panel with a thickness of less than 4 mm or even 2 mm or even thinner.

[0118] According to a fourth possibility, the coated panel comprises a substrate and a wear layer according to the application, but the decorative layer is formed from the surface of the substrate. This is for example the case in a decorative board material, for example a wooden board material, for example for applying the application in solid wood parquet flooring or oriented strand board (OSB).

[0119] According to a fifth possibility, the top layer is formed as described above in one of the first to seventh possibilities, but the substrate is made of a fibre cement board, a magnesium oxide based board, a polyolefin based board, a wood chip board, an OSB, a filled soft PVC board, a filled hard or rigid PVC board, a foam board made of synthetic material, preferably a so-called closed cell foam board made of synthetic material, a multi-layer board such as a multi-ply board or a synthetic material based board with a soft PVC layer and a hard or rigid PVC layer.

[0120] The same objects as in the first to fourth aspects are also achieved according to an independent fifth aspect, to which the application also relates to a coated panel having at least a substrate and a top layer applied thereto, wherein the above-mentioned top layer at least comprises a decorative layer, characterized in that there is a thermoset acrylate resin or a thermoset unsaturated polyester resin between the above-mentioned decorative layer and the substrate, and / or in that the decorative layer is at least partially formed from a thermoset acrylate resin or a thermoset unsaturated polyester resin. According to this fifth aspect, the coated panel does not necessarily have a wear layer. If this is indeed the case, such a wear layer is not necessarily obtained on the basis of a thermoset acrylate resin or on the basis of a thermoset unsaturated polyester resin. The inventors have found that the presence of a thermoset acrylate resin or a thermoset unsaturated polyester resin anywhere in the top layer can lead to an improvement in the click and other properties of the surface. Of course, the acrylate resin or polyester resin and / or the thermal initiator used in the context of the fourth aspect can be the same as those discussed in the context of the first to fourth aspects, it being understood that they do not necessarily lead to a transparent or translucent layer.

[0121] Preferably, the aforementioned decorative layer comprises at least a carrier sheet, such as paper, wherein the thermally cured acrylate resin or the thermally cured unsaturated polyester resin forms a bond between the aforementioned carrier sheet and the substrate. It is clear that the paper of the aforementioned aspects can be used for this purpose.

[0122] Preferably, the thermally cured acrylate resin or the thermally cured unsaturated polyester resin in the fourth aspect is configured to be colored, for example due to the fact that it comprises a pigment, such as titanium oxide. In such a case, the present invention can relate to a white panel which can be used as such, for example as a furniture panel, or which can be used as a semi-finished product in a method in which the white layer is used as a printing substrate which is still to be printed.

[0123] Preferably, the thermally cured acrylate resin or the thermally cured unsaturated polyester resin forms a base layer on which printing is performed, which base layer at least partially forms the aforementioned decorative layer.

[0124] According to an alternative embodiment, the aforementioned decorative layer is a veneer, wherein the thermally cured acrylate resin or the non-thermally cured unsaturated polyester resin preferably extends from the outside of the veneer into and / or through holes, cracks and other openings present in the veneer. As mentioned above, the acrylate resin or the polyester resin is preferably colored. In this way, the acrylate resin or the polyester resin can form a colored filling at the location of the openings, such as knot holes and cracks, in the surface of the veneer.

[0125] In the context of the aforementioned four aspects, it is further noted that for the substrate, wood fiber boards, such as MDF or HDF boards, can be used. According to a particular embodiment, wood fiber boards are used which have a low density, in particular an average density of less than 750 kg per cubic meter, or even 650 kg per cubic meter or lower. In the case of the use of coated panels, mainly in the case of the use of these panels as floor panels in a floating installation, the use of such low density boards contributes to further improving the noise, for example the click noise. The lower residual tensile stress in the panel surface of the aforementioned aspects partly makes it possible to use such low density wood fiber boards. In particular, the risk of the tensile stress in the top layer pulling the upper edge upwards is limited. In prior art laminated panels, this phenomenon is generally prevented or limited by increasing the density of the board. With the top layer of the panel of the present invention, this is no longer necessary.

[0126] According to a particular embodiment, the substrate used is free of unbound formaldehyde or free of formaldehyde. For example, this can be a wood fiber board which is bonded by means of pMDI glue (polymeric methylene diphenyl diisocyanate). In this case, a completely low formaldehyde or formaldehyde-free coated panel is obtained if the top layer is also free of formaldehyde, for example is constructed mainly on the basis of paper and thermally cured acrylate resin and / or polyurethane.

[0127] Further, it is again noted that according to all its individual aspects, the present application allows the above-mentioned top layer to comprise a water-impermeable layer. This is possible because, contrary to melamine formaldehyde, a heat-cured acrylate resin or a heat-cured unsaturated polyester resin does not produce any so-called "chemical" water as a by-product in the polymerization. In case of pressing or curing of melamine resins, it is important that this chemical water can escape to the substrate or surface and, in this case, a water-impermeable layer is an obstacle to be avoided. Preferably, the above-mentioned water-impermeable layer is formed by a layer present between the above-mentioned decorative layer and the substrate. In this way, any moisture present on the surface of the coated panel cannot penetrate into the substrate and a dimensionally stable panel can be obtained in case of humidity changes. This is important, for example, in case the above-mentioned substrate comprises or consists of wood fiber boards. According to another possibility, the above-mentioned water-impermeable layer is formed by an ink layer at least partially forming the above-mentioned decorative layer. Other examples of water-impermeable layers are TPU (thermoplastic polyurethane) films, polyester-based layers, aluminum foils (in particular non-porous aluminum foils), etc. According to all these embodiments, the dimensional stability of the coated panel can be increased.

[0128] In general, it should be noted that according to all its individual aspects, the present application can be applied in a particularly useful manner to coated panels on which the decorative layer comprises a print based on UV-cured ink. As described in WO 2014 / 024100, UV-cured ink can form a strong barrier to the chemical water of the above-mentioned melamine polycondensation reaction, which can lead to various undesirable effects at the panel surface. The present application prevents or limits the formation of chemical water by using a heat-cured acrylate resin in the top layer.

[0129] It is clear that, in the context of the present application, the wear-resistant layer is considered to be the entire layer between the printed decorative layer and the panel surface. Further, it is clear that this wear-resistant layer is preferably substantially or even completely composed using the above-mentioned heat-cured acrylate resin or heat-cured unsaturated polyester resin or cured coating composition comprising an acrylate resin. It is also not excluded that the said wear-resistant layer of the panel surface comprises a further outer coating layer and / or that a part of this wear-resistant layer is formed by a synthetic material of a carrier sheet initially applied to the above-mentioned decorative layer.

[0130] According to a particular embodiment, the wear layer as described above comprises a sheet of material, such as paper. This sheet of material contributes greatly to the impact resistance of the floor panel and reduces the risk of the wear layer, which is usually hard but brittle, breaking. The sheet of material makes the wear layer more resilient, which is also important in the subsequent processing of the edges of the floor panel. The resilience of the wear layer reduces the risk of the edges chipping when milling optional coupling mechanisms. Furthermore, such a sheet of material forms a barrier that prevents any wear or hard particles from entering the still wet wear layer during the production process, so that these particles are more effective in the floor panel obtained. According to its most preferred embodiment, the wear layer comprises a sheet of material which itself comprises embedded hard particles. This can be, for example, a so-called Mead overlay, as described in US 5,820,937, in which an alpha-cellulose paper is filled with aluminum oxide particles or other wear particles at the time of its production. In such an embodiment, the hard particles are particularly held in a fixed position in the thickness of the wear layer, and no special measures are required to suspend the hard particles in the paint layer or in the other material of the wear layer. The latter results in a reduced risk of loss of transparency due to the addition of any suspending agents, and makes the production process more smooth. Also in the processing of the edges, the risk of the hard particles falling out is less, since these hard particles are held together to some extent in the sheet of material.

[0131] As mentioned above, the coated panel of the application, preferably a floor panel, in particular a floor panel intended for floating installation. Preferably, the floor panel is further characterized in that at least two opposite edges are provided with a mechanical coupling assembly, and in the state in which two such floor panels are coupled, these coupling assemblies provide a clamping effect of the upper edges, in particular the wear layers, against each other at the location of the edges. With such an embodiment, a reliable edge water tightness can be obtained. This is important, for example, in the case of the use of a porous and / or wood-based substrate as a substrate, for example in the case of MDF or HDF.

[0132] According to a particular embodiment, the substrate as described above is provided with a coating or impregnation on at least two opposite edges, which prevents or limits the penetration of moisture into the substrate. In the case of a coating, the coating is preferably configured to overlap the edges of the top layer. According to this embodiment, in other words, the edges of the floor panel are provided with a moisture barrier coating, wherein the coating extends from the substrate at least over the border with the top layer. Preferably, the coating further extends, in particular at least over the border with the decorative layer and / or the wear layer.

[0133] In the case of the application of low-density wood fiber boards, in particular with a density of less than 750 or less than 650 kg / m3, to floor panels with mechanical coupling mechanisms, then measures are preferably taken to increase the material quality on the edges of the substrate. For example, an enhancement or impregnation of the edges with MDI or PU can be carried out. Another possibility is to apply an acrylate resin on these edges, which can then be cured, preferably by means of electronic radiation. This curing can optionally be carried out together with the UV or electron beam post-curing described above. Preferably, the acrylate resin applied to the edges is a layer of adhesive acrylate resin. Yet another possibility is the application of urea formaldehyde (UF), melamine formaldehyde (MF) or another resin to at least press in the location where the coupling mechanism is to be formed in the end. In addition, the substrate can be impregnated with PU or MDI from the underside. In most of the existing click systems, such as those of WO 97 / 47834, it is important for the lowermost region of the board, in particular in the location of the lowermost groove lip of the lockable tongue-and-groove connection, to be stable.

[0134] As mentioned above, the wear layer preferably has a structure or relief on its surface, which is formed by indentations. Preferably, this structure helps to imitate the pattern depicted in the printed decor layer and / or the structure forms a delimitation of the printed decor layer, for example on at least one of its edges. For example, in the case of a wood imitation, indentations in the form of wood pores and / or leaf veins can be used for the processing. According to another example, the decor layer can be delimited in the form of bevels or other edges. In the case of a stone decor, structures imitating the mortar joints present can be used. As mentioned above, the present application makes it possible to form such structures or reliefs with deep indentations, for example with indentations of 400 pm or deeper. For example, bevels or other edges with a depth of 400 pm can be formed.

[0135] Preferably, the wear layer is provided with structural elements that penetrate into the substrate, or in other words, in which the decor layer and the underlying substrate are also structured. In particular, such an embodiment is of interest in the realization of structural elements such as edges, since in this way, despite the limited thickness of the wear layer, they can also be given a deeper configuration. The relief obtained in the decor layer itself also contributes here to the realistic imitation of the panel.

[0136] As mentioned above, in the structures or reliefs with deep indentations and / or in the structural elements that penetrate into the substrate, preferably a sufficiently flowable, thermally cured acrylate resin is provided, for example by selecting benzoyl peroxide or methylbenzoyl peroxide as thermal initiator.

[0137] According to a variant, according to one or more of the aforementioned aspects of the application, the application relates to a decorative profile rather than a coated panel. This can be, for example, a profile type used for the finishing of floor coatings, such as a transition profile, a final profile, a skirting board, etc. This variant provides for the smooth production of profiles suitable for decorative panels, for example in particular suitable for the aforementioned coated panels. According to this variant, the application can lead to the production of decorative profiles of floor quality in a simpler manner and thereby creates greater freedom for the design of such profiles.

[0138] The acrylate resin applied in the different aspects of the application can for example have the following composition:

[0139] - 5 to 80% by weight of monomers, or more preferably 5 to 60% by weight, which can be monofunctional, difunctional or polyfunctional, preferably chosen from cyclic monofunctional monomers (CTFA (Cyclotrimethylpropanediol formaldehyde acrylate), TMCHA (trimethylcyclohexyl acrylate), TBCHA (4-tert-butylcyclohexyl acrylate), IBOA (isobornyl acrylate), THFA (tetrahydrofurfuryl acrylate) etc.), alkoxylated monofunctional monomers (PE4A etc.), alkane monofunctional monomers (EOEOEA (2-(2-ethoxyethoxy)ethyl acrylate)), alkoxylated difunctional monomers, alkyl difunctional monomers, polyfunctional monomers (TMPTA (trimethylolpropane triacrylate), GPTA (propoxylated glyceryl triacrylate), PET(T)A (pentaerythritol tri(tetra)acrylate) etc.), acid-based adhesion promoter monomers; preferably monofunctional, difunctional or polyfunctional acrylate or methacrylate monomers are used, preferably trifunctional, in order to limit the risk of the production of unpleasant odours; as a specific example, TMPTMA (trimethylolpropane trimethacrylate) can be used;

[0140] - 0.1 to 10% by weight of additives, such as antifoams, levelling agents; preferably 0.1 to 2% by weight of levelling agents and / or 0.1 to 2% by weight of antifoams are used; as levelling agents, for example silicone polyether acrylates such as TEGORad 2300 can be used; as antifoams, BYK 1790 can be used;

[0141] - 0.1 to 30% by weight and more preferably 1 to 10% by weight of nanosilica or corundum (AI2O3); for example, a dispersion of colloidal (nano)silica in monomers, such as difunctional acrylate monomers, or a dispersion of (nano)silica in butyl acetate or methoxypropyl acetate, or aluminium oxide flakes, for example aluminium oxide flakes with a particle size distribution between 3 and 18 pm, can be used;

[0142] - 5 to 80 wt.-% of oligomers of unsaturated polyesters, polyester acrylates, urethane acrylates, polyether acrylates, melamine acrylates, polycarbonate acrylates, epoxy acrylates, amine-modified acrylates or urethane (meth)acrylates, preferably 2 to 10 functional urethane (meth)acrylates and / or urethane acrylates of the formula A-I-P-I-A, wherein

[0143] • A: acrylic or methacrylic acid, mono- or polyfunctional

[0144] • I: isocyanate (aliphatic monomer or oligomeric di- or polyfunctional)

[0145] • P: polyol long or short chain polyesters, polyethers, polycarbonates, di- or polyfunctional;

[0146] - optionally, fillers, pigments and / or reinforcing agents;

[0147] - 0.1 to 5 wt.-% of thermal initiators, preferably organic peroxides or azo polymerization initiators;

[0148] - optionally, 0.1 to 5 wt.-% of photoinitiators;

[0149] - optionally, 0.1 to 5 wt.-% of crosslinking agents, such as isocyanates, carbodiimides and / or aziridines.

[0150] It is also to be noted that the use of urethane acrylates has the additional advantage of the presence of hydrogen bridges, which leads to a favorable ratio of flexibility to hardness of the layer obtained. It is also possible to use or additionally use so-called "special high-functionality urethane acrylates", for example using silicone-based hydrophilic functions or fluorinated acrylates, together with the so-called "special high-functionality urethane acrylates".

[0151] Optionally, the above composition or the acrylate resin to be cured or the cured saturated polyester can also comprise a photoinitiator, for example 0.1 to 10 wt.-%, preferably 1 to 10 wt.-%. These can be, for example, photoinitiators such as hydroxyacetophenone, acetophenone, aminophenone, phosphine oxide, benzophenone, thioxanthone, benzoylformate or polymeric photoinitiators. These can be, for example, benzophenone or phosphine oxide, such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. Such a composition can further comprise an amine synergist, for example 1 to 10 wt.-%. Such a synergist can facilitate UV curing. The presence of a photoinitiator allows for additional UV curing after thermal curing, for example after hot pressing, whereby a structure is applied to a layer comprising acrylate resin, for example a wear layer. According to another possibility, the acrylate resin or the unsaturated polyester resin can be gelled using a photoinitiator, whereby thermal curing is carried out. For example, the acrylate resin or the unsaturated polyester resin can be gelled on a carrier sheet, for example a paper or decor paper having a print, before this carrier sheet is incorporated into the stack to be pressed. The gelling can also be used to apply a backing layer to the underside of the substrate.

[0152] In addition, the above composition can optionally comprise a UV absorber, for example 0.1 to 5 wt.-%, preferably 1 to 2% or 1.5%. As UV absorber, 2-hydroxyphenyl-s-triazine can be used, which can contain 15-25% of 2-methoxy-1 -propyl acetate (e.g. BASF Tinuvin 477), or bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate containing sebacic acid methyl ester 1,2,2,6,6-pentamethyl-4-piperidinyl (e.g. BASF Tinuvin 292).

[0153] A further optional component of the above composition is a matting agent, such as fumed silica (whether or not treated with wax), precipitated silica, micronized condensation organic polymer. For example, 0.1 to 8 wt.-% of such a matting agent can be used. Actual examples of suitable matting agents are Evonik Acematt 3600 and PQ Corporation Gasil UV55C. In addition, optional components of the above composition are cleaning-promoting additives, anti-slip additives and antibacterial additives. DETAILED DESCRIPTION

[0154] The following lists a number of embodiments of possible compositions:

[0155] Example 1 - wet process single thermal curing

[0156] • 10-40%, preferably 20%, of a hexafunctional aliphatic urethane acrylate

[0157] • 30-80%, preferably 60% of difunctional aliphatic urethane acrylate

[0158] • 5-40%, preferably 18% of difunctional monomer dipropylene glycol diacrylate (DPGDA)

[0159] • 0.1-5%, preferably 0.5-5%, more preferably 1% of TBPIN thermal initiator, i.e. t-butylperoxy-3,5,5-trimethylhexanoate

[0160] • 0.5-1.5%, preferably 1% of a leveling agent

[0161] Example 2 - wet process single thermal cure

[0162] • 10-40%, preferably 20% of hexafunctional aliphatic urethane acrylate

[0163] • 30-80%, preferably 40% of difunctional aliphatic urethane acrylate

[0164] • 5-40%, preferably 20% of trifunctional epoxy acrylate

[0165] • 5-40%, preferably 18% of difunctional monomer dipropylene glycol diacrylate (DPGDA)

[0166] • 0.1-5%, preferably 0.5-5%, more preferably 1% of TBPIN thermal initiator

[0167] • 0.5-1.5%, preferably 1% of a leveling agent

[0168] Example 3 - wet process single thermal cure

[0169] • 10-40%, preferably 20% of hexafunctional aliphatic urethane acrylate

[0170] • 30-80%, preferably 40% of difunctional aliphatic urethane acrylate

[0171] • 5-40%, preferably 20% of trifunctional epoxy acrylate

[0172] • 5-40%, preferably 18% of trifunctional monomer (GPTA - glyceryl triacrylate propoxylated)

[0173] • 0.1-5%, preferably 0.5-5%, more preferably 1% of TBPIN thermal initiator

[0174] • 0.5-1.5%, preferably 1% of a leveling agent

[0175] Example 4 - wet process single thermal cure

[0176] • 10-40%, preferably 20% of hexafunctional aliphatic urethane acrylate

[0177] • 30-80%, preferably 40% of tri-functional aliphatic urethane acrylate, i.e. containing additional isocyanate groups (isocyanate groups) for "instant dual cure"

[0178] • 5-40%, preferably 20% of tri-functional epoxy acrylate

[0179] • 5-40%, preferably 18% of di-functional monomer dipropylene glycol diacrylate (DPGDA)

[0180] • 0.1-5%, preferably 0.5-5%, more preferably 1% of TBPIN thermal initiator

[0181] • 0.5-1.5%, preferably 1% of levelling agent

[0182] Example 5 - wet process single thermal cure

[0183] • 10-40%, preferably 20% of hexafunctional aliphatic urethane acrylate

[0184] • 30-80%, preferably 50% of di-functional aliphatic urethane acrylate

[0185] • 5-30%, preferably 10% of silicone acrylate (2 to 6 functionality), i.e. "special high functionality urethane acrylate" for increased cleanliness

[0186] • 5-40%, preferably 18% of di-functional monomer dipropylene glycol diacrylate (DPGDA)

[0187] • 0.1-5%, preferably 0.5-5%, more preferably 1% of TBPIN thermal initiator

[0188] • 0.5-1.5%, preferably 1% of levelling agent

[0189] Example 6 - wet process single thermal cure

[0190] • 10-40%, preferably 20% of hexafunctional aliphatic urethane acrylate

[0191] • 30-80%, preferably 50% of di-functional aliphatic urethane acrylate

[0192] • 2-15%, preferably 10% of nano-silica dispersed in TMPTA monomer; this results in increased scratch resistance

[0193] • 5-40%, preferably 18% of di-functional monomer dipropylene glycol diacrylate (DPGDA)

[0194] • 0.1 - 5%, preferably 0.5 - 5%, more preferably 1% of TBPIN thermal initiator

[0195] • 0.5 - 1.5%, preferably 1% of a levelling agent

[0196] Example 7 - wet process using gelling - or complete dry process

[0197] The same formulation as in examples 1 to 6 can be used but with the additional 0.1 - 5% (and preferably 0.5 - 5%) of a photoinitiator such as benzophenone, 1- hydroxycyclohexyl phenyl ketone, XBPO

[0198] (phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide), TPO (C 22 H 21P O2) or ITX (isopropyl thioxanthone). It is not excluded and even expected to add a mixture of photoinitiators, one for the surface curing and the other for the deep curing of the paint.

[0199] According to another practical example, the thermally cured acrylate resin consists of the following components:

[0200] - 53.7 parts of aliphatic urethane acrylate;

[0201] - 0.3 parts of benzoyl peroxide;

[0202] - 46 parts of dipropylene glycol diacrylate;

[0203] - optional defoamers, levelling agents, nano-silica and / or corundum (AI2O3).

[0204] Example 8 - wet process using gelling (solvent based) - paint composition comprising the following components (all proportions are in % by weight or parts by weight)

[0205] • 100 parts of component A, the composition of which is:

[0206] o 40 - 90% of hydroxyl functional acrylate in butyl acetate as solvent (30 - 60% of solvent),

[0207] o 0.01 - 1% of crosslinking agent, for example organometallic compound such as dibutyl tin dilaurate or zinc neodecanoate,

[0208] o 0.1 - 5% of photoinitiator,

[0209] o 0.1 - 2% of UV absorber,

[0210] o 0.1 - 2% of light stabilizer,

[0211] o 5-40% of mono, di, tri or tetra functional acrylate monomers

[0212] • 5-20 parts of isocyanate, such as aliphatic polyisocyanate.

[0213] Example 9 - Gelled wet process (solvent based) - Coating composition comprising the following components (all proportions are in % by weight or parts by weight)

[0214] • 30-70 parts of component A, which consists of:

[0215] o 40-90% of hydroxyl functional acrylate in butyl acetate as solvent (30-60% of solvent),

[0216] o 0.01-1% of crosslinker, such as organometallic compound, such as dibutyl tin dilaurate or zinc neodecanoate,

[0217] o 0.1-5% of photoinitiator,

[0218] o 0.1-2% of UV absorber,

[0219] o 0.1-2% of light stabilizer,

[0220] o 5-40% of mono, di, tri or tetra functional acrylate monomers

[0221] • 30-70 parts of isocyanate functional acrylate in solvent

[0222] Example 10 - Gelled wet process (solvent based) - Coating composition comprising the following components (all proportions are in % by weight or parts by weight)

[0223] • 50-90 parts of component A, which consists of:

[0224] o 40-90% of hydroxyl functional urethane acrylate in butyl acetate as solvent (30-60% of solvent),

[0225] o 0.01-1% of crosslinker, such as organometallic compound, such as dibutyl tin dilaurate or zinc neodecanoate,

[0226] o 0.1-5% of photoinitiator,

[0227] o 0.1-2% of UV absorber,

[0228] o 0.1-2% of light stabilizer,

[0229] o 5-40% of mono, di, tri or tetra functional acrylate monomers

[0230] • 10-50 parts of isocyanate functional acrylate in solvent

[0231] Example 11 - wet process single thermal cure

[0232] • 10-80%, preferably 50% of unsaturated polyester

[0233] • 10-50%, preferably 20% of tetrafunctional polyester acrylate

[0234] • 5-40%, preferably 18% of difunctional monomer dipropylene glycol diacrylate (DPGDA)

[0235] • 0.1-5%, preferably 0.-5%, more preferably 1% of TBPIN thermal initiator

[0236] • 0.5-1.5%, preferably 1% of flow agent

[0237] Example 12 - wet process single thermal cure

[0238] • 10-80%, preferably 50% of unsaturated polyester

[0239] • 10-50%, preferably 20% of tetrafunctional polyester acrylate

[0240] • 2-20%, preferably 10% of 10-functional aliphatic urethane acrylate

[0241] • 5-40%, preferably 15% of difunctional monomer dipropylene glycol diacrylate (DPGDA)

[0242] • 1-8%, preferably 3% of alumina

[0243] • 0.1-5%, preferably 0.-5%, more preferably 1% of TBPIN thermal initiator

[0244] • 0.5-1.5%, preferably 1% of flow agent

[0245] Example 13 - wet process using gelling - or fully dry process

[0246] The same formulation as in examples 1 and 2 can be used but with the addition of 0.1-5% of a photoinitiator such as benzophenone, 1-hydroxy-cyclohexyl phenyl ketone, XBPO (phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide), TPO (C 22 H 21P O2) or ITX (isopropyl thioxanthone). Mixtures of photoinitiators are not excluded and are even desired where one photoinitiator is used for surface curing and another for deep layer curing of the paint.

[0247] To better clarify the characteristics of the present application, below reference will be made to the drawings, by way of example, without any limitation, in which:

[0248] Figure 1 a perspective view of a coated panel, more specifically a floor panel, having the characteristics of the present application is shown;

[0249] Figure 2 a larger scale section along Figure 1 line II-II of the panel;

[0250] Figure 3 a schematic representation of the steps of the method having the characteristics of the present application;

[0251] Figure 4 and Figure 5 a sound measurement of a panel having the characteristics of the present application; and

[0252] Figure 6 a method having the characteristics of the present application is shown.

[0253] Figure 1 A coated panel 1 is shown. In this case, it is a rectangular floor panel, comprising a substrate 2 and applied thereon a top layer 3 having at least a decorative layer 4 and a semi-transparent or transparent wear layer 5. The wear layer 5 comprises a thermally cured acrylate resin, wherein the curing is obtained by a thermal initiated free radical crosslinking reaction. To this end, the starting point is a mixture of acrylate resin and thermal initiator. The wear layer can also comprise a cured polyester resin or a cured coating composition comprising acrylate.

[0254] The floor panel 1 is suitable for floating installation and for this purpose, in this case, on the long pair of edges 6-7 and on the short pair of edges 8-9, mechanical coupling means 10 are provided, which allow two such floor panels 1 to be connected to each other at the respective edges 6-7-8-9.

[0255] Figure 2 It is again clear that, Figure 1 at least the long pair of edges 6-7 of the floor panel 1 have mechanical coupling means 10, mainly in the form of teeth 11 and grooves 12, wherein two such floor panels 1, in the coupled state at these edges 6-7, have a locking between the teeth 11 and the grooves 12 in a first direction R1 perpendicular to the surface 13 of the coupled panels 1 and in a second direction R2 perpendicular to the coupled edges 6-7 and in the plane 13 of the panels 1.

[0256] Preferably, on the short edges 8-9, as in Figure 1 and 2In some implementations, a mechanical coupling mechanism 10 is also provided, which provides locking in the respective direction, whether or not primarily in the form of teeth 11 and slots 12.

[0257] for Figure 2 In this embodiment, a substrate 2 comprising wood fiberboard with a density of 750 kg / m³ or less is used. To improve the bonding strength of the connecting mechanism 10, the edges 6-7 of the substrate 2 are impregnated with MDI (methylene diphenyl diisocyanate) 14. As mentioned above, it is important that the lowermost lips 15 located on both sides of the groove 12 are constructed sufficiently robust. To limit swelling that may occur during the milling of the connecting mechanism 10 due to penetration and / or printing effects, it is also desirable to reinforce the substrate material 2 by impregnation or other means near the upper edge 16.

[0258] In this example, a backing layer 18 is also provided on the lower side 17 of panel 1. This is preferably done on a thermosetting acrylic resin and its main purpose is to form a barrier against the rise of moisture. As described in the invention, the residual stress of the abrasion layer 5 is low, so the backing layer 18 only serves as a minimal balancing layer. Therefore, the backing layer 18 can also be omitted, especially when the substrate 2 itself is composed of a waterproof material and / or has a waterproof lower side 17 and / or is treated to have some degree of hydrophobicity at least on the lower side 17 of the substrate 2, for example, when the substrate material is impregnated with MDI on the lower side 17.

[0259] Figure 1 and 2 The decorative layer 4 of the floor panel 1 comprises a carrier sheet provided with synthetic material 19, and more specifically, has a surface weight of approximately 70 g / m². 2 Paper 20. Paper 20 shows a print 21 in the form of a wood-based graphic. The synthetic material 19 used contains double carbon bonds, more specifically polyurethane.

[0260] Figure 3 It was given again Figure 1 and 2 A schematic diagram of several steps in the manufacturing process of the floor panel.

[0261] In this example, the decorative layer 4 containing at least the paper sheet 20 is considered as a reference. The paper sheet 20 itself has a print 21. In a first step S1, the paper sheet 20, more specifically a paper web from which the paper sheet 20 is subsequently obtained by cutting, is provided with a synthetic material 19. To this end, the paper web is unwound and immersed in a core by the first synthetic material 19. The core immersion can limit the risk of paper sheet 20 splitting in the final coated panel 1. In this example, this core immersion is carried out in two sub-steps, specifically in a first sub-step S1A, the synthetic material 19 is applied by means of a roller 22, and in a second sub-step S1B, the paper sheet 20 is immersed in a bath 23 containing the synthetic material 19. In this example, the synthetic material 19 applied in the first sub-step S1A and the second sub-step S1B is identical. However, the synthetic materials used in the first and second sub-steps can also be different from each other, independently of the specific application technique used. Between the first sub-step S1A and the second sub-step S1B, the paper sheet 20 follows a trajectory 24 which allows the first synthetic material 19 applied during the first sub-step S1A to penetrate sufficiently. As mentioned in the introduction, as first synthetic material 19, a modified melamine formaldehyde resin, a modified urea formaldehyde resin or a modified melamine urea formaldehyde resin can be used. Preferably, the first synthetic material 19 comprises double carbon bonds. Preferably, the first synthetic material 19 is selected from the group consisting of polyurethanes, urethane-acrylate copolymers, acrylates, latexes and dispersions combined with acrylate functionality.

[0262] Figure 3 It is further shown that, after the above-mentioned core immersion, for example, in this case, aluminium oxide particles can be applied in a third sub-step S1C, for example by a scattering treatment. Preferably, subsequently in a fourth sub-step S1D, a drying treatment is carried out in a hot air oven 25. Optionally, in a fifth sub-step S1E, on one side of the print 21 and / or on the side of the paper sheet 20 intended to face the wear layer 5, an intercoat layer 26 can be applied which increases the compatibility with the wear layer 5 to be formed from a thermally cured acrylate resin or a thermally cured unsaturated polyester resin or a coating composition comprising an acrylate resin. For example, such an intercoat layer can consist of a water-based polyurethane coating, a water-based UV-curing substance or a melamine acrylate or a reactive acrylate monomer. During the same step S1E or in a separate step, a coating 27 can also be applied on the side of the paper sheet 20 intended to face the substrate 2. The purpose of such a coating 27 is to provide a better adhesion to the substrate 2. According to another possibility, such a coating 27 can also serve to provide noise damping. In the latter case, a polyurethane is preferably used, for example an aromatic polyurethane or a thermoplastic polyurethane (TPU). After the application of the intercoat layer 26 and / or the coating 27, as in the present example, a drying treatment similar to the fourth sub-step S1D can again be carried out.

[0263] In a seventh sub-step S1F, in the present example, the treated paper 20 passes through a cooling roller 28 and the web is divided into sheets.

[0264] In a second step S2, a stack 29 is formed comprising at least the substrate 2 and the decorative layer 4, in which case the decorative layer 4 comprises the printed paper 20 provided with synthetic material 19 obtained in step S1.

[0265] The method of the present application comprises at least a third step S3, in particular a step of applying to the decorative layer 4 an acrylate resin (or an unsaturated polyester resin or a coating composition comprising an acrylate resin) comprising a thermal initiator, and a fourth step S4, in particular a step of curing the above-mentioned resin by hot pressing. In the third step S3, an acrylate resin with thermal initiator is applied to the lower side of the substrate 2 to form the backing layer 18. It is clear that in this case the third step S3, in particular the step of applying the resin to the decorative layer 4, is carried out when the decorative layer 4 is already part of the stack 29 comprising at least the substrate 2 and the decorative layer 4.

[0266] In the example shown, the pressing is carried out by means of a so-called short cycle press 30 and more particularly by means of structured pressing elements 31 or pressing plates. The pressing is carried out on the stack 29 comprising the substrate 2, the decorative layer 4, the acrylate resin of the wear layer 5 and the backing layer 18. During the pressing, the structure 32 of the pressing elements 31 is reproduced in the surface of the wear layer 5.

[0267] Figure 4 Noise measurements are shown by curves 33-34, which were carried out on the one hand on a melamine surface of a prior art floor panel (curve 33) and on the other hand on a thermally cured acrylate surface of a floor panel according to the present application (curve 34). These are curves of the measured loudness (in units of phons) of the scraping noise (shown on the ordinate 35) as a function of the frequency (Hz) (shown on the abscissa 36), which was produced with a metal pin on the surface. The loudness is a variable that objectively reflects the noise level that is subjectively experienced. In the results shown in curve 33 for the melamine surface, a very large and very broad peak can be found in the frequency interval of 1000 to 5000 Hz, in which the human ear is most sensitive. The user will experience this noise as very annoying. When the same scraping is carried out on the thermally cured acrylate surface, the results of curve 34 show a clear decrease in the absolute loudness in the same time interval. This results in a warm and less high noise being perceived, comparable to the noise produced on a wooden surface.

[0268] Figure 5The results of the loudness measurements shown by curves 37-38, which were carried out on one hand on the melamine surface of a prior art floor panel (curve 37) and on the other hand on the thermally cured acrylate surface of a floor panel according to the application (curve 38). The prior art floor panel comprises a substrate of HDF, in particular a wood fiber board having an average density of about 950 kg per cubic meter. The floor panel according to the application comprises a substrate of MDF, more in particular a wood fiber board having an average density of about 650 kg / m 3 The results are curves of the measured values of the loudness of the click sound (in units: phons) as a function of the frequency (Hz) (shown on the ordinate 35) with a metal pin producing the click sound on the surface. The results show that the click sound on the floor panel according to the application is less loud and that the peak disappears in the interval of 1000 to 5000 Hz. This results in a warmer and more wood-like noise.

[0269] Figure 6 Another aspect of the production of a coated panel 1 having the features of the application is shown. In this case, it is a method of producing a floor panel 1 having a substrate 2 of synthetic material or synthetic material composite, for example an LVT (luxury vinyl tile) type floor panel comprising a substrate 2 of high-filled soft, semi-rigid or rigid PVC. The substrate 2 can be formed by extruding the synthetic material or the composition, or in the case here, in a first step T1, by one or more scattering operations in which particles 39 or powders having the appropriate composition are deposited on a conveyor belt 40 and consolidated between the belts 41 of a double-belt press. In a second step T2, a printed film made of synthetic material 24 can be unwound onto the formed substrate 2 to form the decorative layer 4, and in a third step T3, a translucent film made of synthetic material 43 can optionally be unwound to form at least part 5A of the wear layer 5. In a fourth step T4, a mixture of at least acrylate resin and thermal initiator is applied to the obtained whole, preferably to the translucent film made of synthetic material 43, for example by one or more rollers 44. The substrate 2, the film or films made of synthetic material and the mixture of acrylate resin and thermal initiator are then consolidated or cured in a fifth step T5 by a hot roller 45. In the example shown, a structured roller is used. Finally, the structure 32 of the roller 45 is advantageously imprinted in the thermally cured acrylate resin. Such a method results in a wear layer 5 having excellent aesthetic and mechanical properties without the need for an additional surface UV-cured varnish layer as in prior art LVT floor panels.

[0270] As Figure 6Alternatively to the method shown, it is also possible to apply a mixture of acrylate resin and thermal initiator to a semi-finished product (whether consolidated or not), which comprises a substrate of synthetic material or a composite of synthetic material and at least a decorative layer, for example to a semi-finished product having a substrate, a printed film made of synthetic material and, optionally, a transparent film made of synthetic material positioned on said print. It is then possible to press the entire semi-finished product and the mixture in a short-cycle press similar to the press 30 shown in step S4. Figure 3 The entire semi-finished product and the mixture are then pressed in a short-cycle press similar to the press 30 shown in step S4.

[0271] It is clear that the method shown and mentioned in the introduction can be carried out completely or partially on a larger panel, slab or continuous web. In this case, the actual coated panel is obtained after separating said panel, slab or web, if at all.

[0272] The present application is by no means limited to the above-described embodiments; rather, this coated panel and the method for producing it can be realized without departing from the scope of the present application. In addition, the concept of the present application can also be applied to textured packaging materials or flat materials, such as posters, stationery or laminates for laminated profiles, such as skirting boards and cladding profiles for floors. The present application therefore also relates to a method for producing a packaging material or a flat material, characterized in that the method comprises the steps of applying a heat-curable acrylate resin or a heat-curable unsaturated polyester (for example with a thermal initiator) to the actual packaging material or flat material (for example paper, cardboard, a film made of synthetic material, a synthetic material) and at least partially curing the acrylate resin or unsaturated polyester mentioned above by means of hot pressing, wherein a structured pressing element or a press film is preferably used. It is clear that this method can further exhibit the preferred features of the present application according to the third aspect without the coated panel having to be obtained.

Claims

1. A method for producing a coated panel, wherein the coated panel (1) comprises at least a substrate (2) and a top layer (3) applied thereon, and the top layer (3) comprises at least a decorative layer (4) and a semi-transparent or transparent wear layer (5), wherein the decorative layer (4) comprises a printed paper impregnated with a thermosetting resin, wherein the method comprises at least the following steps: - a step (S3) of applying to the decorative layer (4) a coating composition comprising an acrylate resin or an unsaturated polyester resin; wherein the coating composition comprises a thermal initiator and a photo initiator; and - a step (S4) of at least partially curing the coating composition by hot pressing to form at least a part of the wear layer (5), wherein, after the step (S3) of applying the coating composition to the decorative layer (4); and before the step (S4) of at least partially curing the coating composition by hot pressing to form at least a part of the wear layer (5); the method comprises a step of gelling the coating composition into a non-tacky state, wherein in the step of gelling the coating composition, the coating composition is gelled by UV radiation.

2. The method according to claim 1, wherein the gelling is carried out under inert atmosphere.

3. The method according to claim 1, wherein after the hot pressing, further curing is carried out by UV radiation or electron beam curing.

4. The method according to claim 1, wherein in the hot pressing operation, full curing is achieved.

5. The method of claim 1, wherein, The pressing is carried out with the aid of a structured pressing element (31), wherein a relief is formed in the top layer by the structured pressing element (31).

6. The method according to claim 1, wherein the pressing is carried out by a short cycle press (30).

7. The method according to claim 1, wherein the pressing is carried out by a continuous type press or a hot press roller.

8. The method according to claim 1, wherein the pressing is carried out on a stack (29) comprising at least the substrate (2), the decorative layer (4) and the coating composition.

9. The method according to claim 1, wherein the step (S3) of applying the coating composition to the decorative layer (4) is carried out when the decorative layer (4) is already part of a stack (29) comprising at least the substrate (2) and the decorative layer (4).

10. The method according to claim 1, wherein the coating composition comprises an acrylate resin, wherein the acrylate resin comprises a mono- or di- or tri-functional acrylate monomer; and an oligomer.

11. The method according to claim 1, wherein the thermosetting material impregnating the paper is selected from amino resins.

12. The method according to claim 1, wherein the thermosetting material impregnating the paper is selected from polyurethanes.

13. The method according to claim 1, wherein the thermosetting material impregnating the paper is selected from acrylates.

14. The method according to claim 1, wherein the thermosetting material impregnating the paper is selected from urea formaldehyde or melamine formaldehyde.

15. The method according to claim 1, wherein the thermosetting material impregnating the paper is selected from melamine urea formaldehyde.

16. The method according to claim 1, wherein the thermosetting material impregnating the paper is selected from urethane-acrylic copolymer.

17. The method according to claim 1, wherein the thermosetting material impregnating the paper is selected from melamine acrylate.

18. The method according to claim 1, wherein the thermosetting material impregnating the paper is latex.

19. The method according to claim 1, wherein the thermosetting material impregnating the paper is dispersion.

20. The method according to any one of claims 11 to 19, wherein the thermosetting material is combined with a crosslinking agent.

21. The method according to claim 1, wherein before the step (S3) of applying the coating composition to the decorative layer (4), the method comprises a step of applying an adhesion promoter to the decorative layer.

22. The method according to claim 21, wherein the adhesion promoter comprises or consists of polyurethane.

23. The method according to claim 22, wherein the adhesion promoter comprises or consists of a polyurethane dispersion.

24. The method according to claim 23, wherein the polyurethane dispersion is selected from a water-based polyurethane dispersion or a polyurethane dispersion having acrylate functionality.

25. The method according to claim 21, wherein the adhesion promoter comprises or consists of an acrylate primer.

26. The method according to claim 25, wherein the acrylate primer is selected from a reactive low viscosity acrylate primer.

27. The method according to claim 21, wherein the adhesion promoter comprises or consists of melamine acrylate.

28. The method according to claim 1, wherein the substrate comprises a thermoplastic selected from PVC, polypropylene or polyethylene; wherein the thermoplastic is filled with a filler; and wherein the decorative layer comprises a printed film made of synthetic material; or wherein the decorative layer comprises or consists of a print on the substrate.

29. The method according to claim 1, wherein the substrate comprises or consists of wood fiber board or wood chip board.

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