EP4496705A1

EP4496705A1 - Panel comprising a timber layer

Info

Publication number: EP4496705A1
Application number: EP23717641.7A
Authority: EP
Inventors: Benjamin Clement; Bruno Vermeulen; Martin Segaert; Pieter-Jan SABBE; Laurent Meersseman
Original assignee: Unilin BV
Current assignee: Unilin BV
Priority date: 2022-03-23
Filing date: 2023-03-17
Publication date: 2025-01-29
Also published as: WO2023180886A1

Abstract

A panel 1 comprising a top layer 2 and a substrate 4, wherein the top layer 2 comprises at least one timber layer comprising interruptions 3 such as cracks and/or voids and/or pits, and wherein said timber layer is attached to the substrate 4 and color is visible at the height of the interruptions 3, and method to produce such a panel 1.

Description

Panel comprising a timber layer

[01] The present invention relates to panels comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits.

[02] The present invention also relates to methods for producing such panels.

[03] Timber layers can have defects/interruptions such as cracks and/or voids and/or pits. If such timber layers are used to form panels, it is important to fill up these cracks and/or voids and/or pits. This for aesthetic reasons and/or also to prevent premature wear. The timber layer is weak at the height of said interruptions. In practice said interruptions are often filled up with wood putty and/or wood filler. Said filling up normally takes place after the gluing of the timber layer to the substrate and also after any treatments of the timber layer, namely the application of a lacquer layer, an oil layer, a paint/varnish, etc. This means that an additional and separate step is needed to fill up these interruptions. In this additional step, the cracks and/or voids and/or pits are filled up with wood putty or wood filler in excess and the excess wood putty or wood filler is sanded away. This is a time-consuming step and further the end result is often not that good looking. At the borders of the cracks and/or voids and/or pits, unwanted residues of said wood putty or wood filler can stay behind and/or the cracks and/or voids and/or pits are not filled up homogenously and/or as desired. Further said sanding reduces the thickness of the wood layer.

[04] It is therefore an object to of the invention to provide an alternative panel and method to produce such a panel, which solves one or more of the abovementioned problems of existing panels comprising timber layers with cracks and/or voids and/or pits and methods to produce these panels. [05] The invention provides various independent aspects which fulfill the intended objective.

[06] This object is achieved by providing a panel according to a first aspect of the invention, comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, and wherein said panel comprises a glue layer, for example a separate glue layer, by which the top layer is attached the substrate, wherein the glue layer comprises colored fillers, such as pigments and/or wood particles, located at least at the height of the interruptions. The glue layer comprises colored fillers which are at least located at the height of the interruptions. Since the timber layer is attached to said substrate by said glue layer, thus glued upon the substrate, this means that said glue layer is visible, and also said colored fillers are visible, at the height of the interruptions. For aesthetic reasons, it becomes redundant to fill up said interruptions with wood putty or wood fillers, and this because said colored fillers already provide the necessary aesthetics.

[07] The glue layer can comprise one or several types of glue, for example a thermoset glue or a thermoplastic glue. Examples of possible glues are aminoplast polymer glues such as urea formaldehyde glues, melamine urea formaldehyde glues or melamine formaldehyde phenolic glues. Other possible glues are polyvinyl acetate glues, polyurethane glues, poly acrylate glues, polymeric methylene difenyl di-isocyanate glues, polyvinyl butyral (PVB) glues, polyurethane (PUR) hotmelts, polyester glues, bio-based glues based on for example sugars, lignin, hyper branched polyamides, etc. It is not excluded that the glue contains an additional hardener to improve the bonding, such hardener can be based on for example isocyanates, carbodiimides, aziridine, epoxy, etc.

[08] The glue layer can here be a separate glue layer, meaning an additional glue layer that is added to connect to the top layer to the substrate. Said additional glue layer can comprise a thermoset glue or a thermoplastic glue as described above. Said additional glue layer can comprise at least 80% or at least 90% by weight of a glue, for example at least 80% or at least 90% by weight of a resin. Said glue layer can or cannot comprise a sheet, such as a paper sheet or a plastic sheet. This paper or plastic sheet can be colored sheet, such as a black or brown or white sheet, but can also be a transparent sheet. For example said glue layer can comprise or can be a resin impregnated sheet. The glue layer can comprise or can be a sheet impregnated with polyurethane, for example can be paper sheet impregnated with a polyurethane dispersion, for example a transparent water based polyurethane dispersion. This paper sheet can be colored paper sheet, such as a black, white or brown paper sheet, but can also be a transparent paper sheet. An advantage of polyurethane is that, if the top layer comprises a said timber layer and at least one UV curable lacquer layer applied upon said timber layer, one does not have to apply an additional primer to the timber layer, since said UV curable lacquer layer can directly adhere to the polyurethane. Further polyurethane is less prone to shrinkage when being for example pressed. The colored fillers can be fully embedded in the glue and/or can be partially embedded in the glue. For example the colored fillers can be attached to the resin at the height of a surface of a resin impregnated paper, as such forming a glue layer comprising a resin impregnated paper and colored fillers.

[09] A possible example of a glue layer is the following: The glue layer comprises a paper sheet. The paper sheet can be a colored paper sheet of for example between 50 and 120 gsm. The color is for example black or brown. The paper sheet can also be a transparent sheet of for example between 25 and 50 gsm. Said paper sheet is impregnated with polyurethane, preferably with a transparent and water based polyurethane dispersion, and this preferably until a weight of substantially 120 gsm, in case of a colored paper sheet, or until a weight of substantially 65 gsm, in case of a transparent paper sheet. Said weight is the weight of the paper, the polyurethane and the residual moist. The residual moist is preferably lower than 10 weight percentage, more preferably lower than 7 weight percentage, this for example measured after 5 minutes at 160°C. If the residual moist is too high, this can result in local delamination and/or discoloration of the top layer. Instead of polyurethane, a melamine formaldehyde resin or another glue can be used. Further preferably a coating is applied to one side of said impregnated paper sheet, the side at the height of the top layer. This is a colored coating, preferably water based. This coating can be applied inline with the impregnation of the paper sheet. Said coating comprises preferably polyurethane, pigments and other (colored) fillers. For example the coating comprises 1 to 10 weight percentage pigments and 2 to 20 weight percentage other fillers, such as koalin, wood dust, silica, aluminosilicates, glasbeads or aluminum oxide. The average particle size of the other fillers can be between 5 and 80 micron, preferably between 5 and 50 micron. The pigments provide the desired color, while the other (colored) fillers mainly ensure the desired haptic and texture. The said other fillers could comprise porous particles, which can easily absorb color, such that the glue layer is a stainable glue layer.

[10] Another possible example of a glue layer is the following: The glue layer comprises a paper sheet. The paper sheet can be a colored paper sheet of for example between 50 and 120 gsm. The color is for example black or brown. The paper sheet can also be a transparent sheet of for example between 25 and 50 gsm. Said paper sheet is impregnated with polyurethane, preferably with a transparent and water based polyurethane dispersion, and this preferably until a weight of substantially 120 gsm, in case of a colored paper sheet, or until a weight of substantially 65 gsm, in case of a transparent paper sheet. Said weight is the weight of the paper, the polyurethane and the residual moist. The residual moist is preferably lower than 10 weight percentage, more preferably lower than 7 weight percentage, this for example measured after 5 minutes at 160°C. If the residual moist is too high, this can result in local delamination and/or discoloration of the top layer. Instead of polyurethane, a melamine formaldehyde resin or another glue can be used. Further preferably a coating is applied to one side of said impregnated paper sheet, the side at the height of the top layer. This is a colored coating, preferably water based. This coating can be applied inline with the impregnation of the paper sheet. Said coating comprises preferably polyurethane and fillers of which some are preferably colored fillers. For example the coating comprises 2 to 20 weight percentage fillers, such as koalin, wood dust, silica, aluminosilicates, glasbeads or aluminum oxide. The average particle size of the fillers can be between 5 and 80 micron, preferably between 5 and 50 micron. The said fillers could comprise porous particles, which can easily absorb color, such that the glue layer is a stainable glue layer.

[11] In an alternative embodiment, instead of the glue layer comprising colored fillers, such as wood particles, the glue layer comprises a colored paper sheet, for example a black, white or brown colored paper sheet with for example a weight of between 50 and 120 gsm, specifically 65 gsm. Said colored paper sheet is impregnated with a polyurethane, a melamine formaldehyde resin or another glue, for example a transparent water based polyurethane dispersion. The impregnation is preferably until a weight of between 120 and 140 gsm. Said weight is the weight of the paper, the polyurethane and the residual moist. The residual moist is preferably lower than 10 weight percentage, more preferably lower than 7 weight percentage, this for example measured after 5 minutes at 160°C. If the residual moist is too high, this can result in local delamination and/or discoloration of the top layer.

[12] The glue layer can also be part of the substrate, wherein the substrate for example forms the glue layer during the production of said panel. This is further clarified.

[13] The colored fillers can comprise pigments and/or wood particles, such as wood dust, for example wood sawdust, wood fibers or wood chips. Other colored fillers can be inorganic fillers such as (iron) silicates, aluminosilicates, calcium carbonates, etc.

[14] In a specific embodiment the glue layer can comprise thermoplastic material and can be part of a thermoplastic layer, wherein this thermoplastic layer is for example part of the substrate or forms the substrate. With a thermoplastic layer is meant a layer comprising preferably at least 10 percent by weight of thermoplastic material, more preferably 20 percent by weight or at least 20 percent by weight and in a specific embodiment at least 30 percent by weight. The thermoplastic layer can comprise between 18% and 22% by weight of thermoplastic material. For example the thermoplastic layer can be a PVC based layer, a polyvinyl butyral (PVB) based layer, or a polyethylene (PE) based layer, or a polypropylene (PP) based layer, or a polylactide (PLA) based layer. The said timber layer is for example laminated/heat pressed upon a thermoplastic layer, wherein said thermoplastic layer forms the substrate and wherein the thermoplastic material at the height of the timber layer melts during pressing and as such connects the timber layer to the substrate. A panel according to the first aspect of the invention is thus formed. Preferably said glue layer fills up said interruptions. Said thermoplastic layer can substantially comprise thermoplastic material. Said thermoplastic layer can also comprise particles, such as wood fibers, wood chips, chalk or other fillers, which are glued together with a said thermoplastic material. Said particles can be colored particles, which then form the colored fillers.

[15] With heat pressing is meant pressing with the pressure condition temperature being preferably higher than 60°C, more preferably higher than 80°C and most preferably higher than 100°C. Preferably said glue layer only adheres the timber layer to the substrate, and only at the height of the interruptions, the glue layer is located higher with regard to the substrate. Here the glue layer at least partly fills up the interruptions.

[16] Preferably the glue layer penetrates at most 50 percent of the thickness of the timber layer, more preferably at most 30 percent, most preferably at most 10 percent. In this way the top surface of the timber layer is not negatively influenced by the glue layer. If pressing is used to produce the panel, the pressing conditions can be chosen in such a way that the glue layer only penetrates the desired percentage of the thickness of the timber layer. For example the time and/or the temperature and/or the pressure can be chosen. It is also possible to work with at least two pressing operations, for example a first milder pressing operation, a so- called prepressing, followed by a second pressing operation. It is not excluded that once the glue layer has penetrated 10% in the timber layer or another percentage, a cooling operation is started during pressing, to solidify the glue layer before opening the press. The solidification can for example start once the temperature is below 50 °C. By this, it can be prevented that the glue layer penetrates the timber layer too much.

[17] In other embodiments, the glue layer can penetrate at least 50 percent, or at least 70 percent, or at least 90 percent of the thickness of the timber layer, or the glue layer can penetrate the entire thickness of the timber layer. In this way the timber layer is strengthened by the glue.

[18] The panel can further comprise one or several wear resistant layers applied on top of the timber layer, such as one or several lacquer layers and/or oil layers.

[19] The panel can comprise one timber layer, but can also comprise two or more timber layers adhered to each other. If said panels comprises two or more timber layers, said timber layers are preferably arranged on top of each other in their original order and orientation in the timber piece from which they are cut, such that interruptions are located on top of each other. The one or more timber layers may or may not be compressed timber layers. The thickness of said compressed timber layer can be at least 70%, or at least 80% or at least 90% of the thickness of the original timber layer.

[20] Preferably the glue layer is penetrated into said interruptions according to a direction perpendicular to the plane in which the panel extends. This direction is here the thickness direction of said timber layer. Because said glue layer has penetrated into said interruptions, the glue layer provides additional strength to said timber layer at the height of said interruptions, such that said interruptions no longer form less weak points of said timber layer, making the timber layer for example more resistant to wear. If further one or several wear resistant layers are applied on top of the timber layer, said filled up interruptions make sure that not much material is needed to form said wear resistant layers. In addition to the penetration into said interruptions, the glue layer can also penetrate a certain percentage of the thickness of the timber layer as described above.

[21] Further preferably the glue layer is located between an upper surface and a bottom surface of the panel. Thus, said glue layer does not extend beyond the panel according to the abovementioned direction, e.g. beyond the timber layer and does not form protrusions of the panel.

[22] In a specific embodiment the thickness of the timber layer is less than 1,5 mm, preferably at most 1 mm, more preferably at most 0.7 mm. Also preferably the timber layer is at least 0,2 mm and more preferably at least 0,4 mm. The thickness of the timber layer is preferably between 0,2 mm and 1 mm, more preferably between 0,4 mm and 0,7 mm. The thickness is here the thickness of the timber layer in the panel. It has been found that the invention is specifically useful for panels in which the timber layer is thin. The filling up of cracks/pits/voids of thin timber layers, being thin veneer layers, with wood putty or wood filler, is more difficult than for thicker timber layers and also results in more unwanted residues of wood putty or wood filler surrounding said cracks/pits/voids. Further, a sanding step to take away such residues cannot be performed upon thin wood veneers or can only be performed in a small amount. The invention thus ensures that even with thin veneers, a desired panel is obtained.

[23] In another embodiment the timber layer is thicker than 1,5 mm. The timber layer can be thicker then 2,5 mm and the panel can then be named parquet.

[24] In a preferred embodiment the said colored fillers are substantially, and preferably only, located at the height of the interruptions. This ensures that the number of colored fillers is limited.

[25] In a specific embodiment, the colored fillers are substantially, and preferably only, located at the top side of the glue layer. Said colored fillers can be present over substantially the entire top side or substantially, preferably only, at the height of the interruptions. The said colored fillers form or they form together with for example the glue of the glue layer, the top of the glue layer. In this specific embodiment the glue layer can comprise promoters which promote the adhesion between the colored fillers and the glue of the glue layer.

[26] In another embodiment the colored fillers extend homogenously throughout the glue layer.

[27] In a specific embodiment the glue layer comprises a transparent or translucent base material. Preferably said transparent or translucent base material is colorless or only has a light color. This ensures that said glue layer will not cause an undesirable discoloration of said timber layer. Further it is possible that a top surface of the substrate is visible trough said interruptions and said top surface can have the desired color and/or appearance, for example the top surface can be a colored top surface, such that said top surface contributes to the aesthetic appearance of the panel.

[28] In another embodiment the glue layer is substantially opaque. The substrate is then not or hardly visible at the height of the interruptions.

[29] Preferably the colored fillers comprise pigments. With pigments it is possible to obtain the desired color for the interruptions and this in a consistent way.

[30] In an embodiment the colored fillers comprise wood particles. With the aid of wood particles, a very natural look can be obtained. Said wood particles can be sufficiently small, for example the wood particles can be wood dust, such as wood sawdust, wood fibers or wood chips. If wood dust is used, glue and wood dust can be mixed to obtain said glue layer. Further wood particles contribute to the strength of the panel, such that the panel can have a sufficient wear resistance.

[31] The colored fillers can comprise both pigments and wood particles and this to have a natural look with the desired color. [32] In a specific embodiment the substrate is wood-based, such as an HDF, a MDF or a particleboard. The substrate can also comprise at least one thermoplastic layer, wherein said glue layer is part of said substrate, or said glue layer is an additional glue layer with respect to said substrate and said top layer. The substrate can for example be a filled thermoplastic substrate, filled with mineral fillers, such as chalk, or plant based fillers, such as wood fibers. The substrate can comprise polyvinylchloride (PVC), polyethylene (PE), polypropylene (PP), polyvinylbutyral (PVB), polylactic acid (PLA) etc. The substrate can also be a mineral based or a geopolymer based substrate, such as a magnesium based substrate (MgO based substrate), a cement based substrate, a gypsum based substrate, etc.

[33] The object of the invention is also obtained by providing a panel according to a second aspect of the invention. This panel comprises a top layer and a substrate, with the top layer attached to a top surface of said substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, wherein at least the top surface of the substrate is colored and wherein said top surface of substrate is visible through said interruptions. Since at least the top surface of the substrate is colored, and said colored top surface is visible through said interruptions, the panel can have an aesthetic appearance and this without the need for wood fillers and/or wood putty. The top surface can have a dark color, such as black, or dark brown. Said panel can have a separate glue layer substantially located between the timber layer and the substrate or said timber layer can be directly attached to said substrate, wherein the substrate then provides the attachment with the timber layer. For this the substrate can for example comprises thermoplastic material, such that the timber layer can be heat pressed upon the substrate, upon which the thermoplastic material melts and can attach to the timber layer. Said substrate may or may not be stainable. If said substrate is stainable, the color at the height of the interruptions can be changed by the end client.

[34] Preferably the substrate is a wood-based board, such as a fiberboard, a particle board or a timber layer. This results in a more natural look. The substrate can also be a mineral based or geopolymer based substrate such as a MgO based substrate, a gypsum-based substrate or a cement-based substrate and can thus for example be a (fiber) cement board, a gypsum (fiber) board, etc. The substrate can also be a plastic based substrate such as a PVC based substrate, a PVB based substrate, a PP based substrate, a PLA based substrate or PE based substrate. The substrate can for example be a filled thermoplastic substrate, filled with mineral fillers, such as chalk, or plant based fillers, such as wood fibers.

[35] The top surface of the substrate is for example stained or painted.

[36] In a specific embodiment the substrate comprises at least two sublayers, with a top sublayer comprising pigments, such that the top surface of said substrate is colored. Said sublayer can for example comprise cellulose powder, a resin and dark colored pigments, such as black pigments. The substrate can for example comprise a fiberboard, such as a MDF (medium-density fiberboard), or a HDF (high-density fiberboard) with a top sublayer comprising a mixture of cellulose powder, a resin and dark colored pigments. Further by making use of such a top sublayer, the resin type or the amount of resin can be chosen in such a way that the timber layer can better and/or more easily attach to the substrate. The resin can comprise aminoplast polymer glues, polyvinyl acetate glues, polyurethane glues, poly acrylate glues, polymeric methylene difenyl di-isocyanate glues, polyvinyl butyral (PVB) glues, PUR hotmelts, polyester glues bio-based glues based on for example sugars, lignin, hyper branched polyamides, etc. It is not excluded that the resin contains an additional hardener to improve the bonding, such hardener can be based on for example isocyanates, carbodiimides, aziridine, epoxy, etc.

[37] In another specific embodiment the substrate is a thermoplastic based substrate, such as a PVC based substrate, a PVB based substrate, a PP based substrate, a PLA based substrate or a PE based substrate, wherein the timber layer is attached, for example heat pressed, upon the substrate, wherein the substrate, at least at the height of the timber layer comprises colored fillers, such as pigments or wood particles. Said substrate then for example comprises at least one layer comprising wood particles glued together by a thermoplastic glue, wherein said layer forms the top layer of the substrate upon which the timber layer is attached. Said top layer is thus visible trough said interruptions and preferably said top layer has penetrated said interruptions. By heat pressing, the substrate can at least partially melt at the height of the timber layer, as such allowing a good attachment between the timber layer and the substrate. Said substrate then forms a glue layer.

[38] In a specific embodiment the panel comprises a transparent or translucent glue layer by which the timber layer is attached to the substrate. The timber layer is thus glued upon the substrate. Because said glue layer is transparent or translucent, the top surface of the substrate is visible trough said interruptions. If further said glue layer comprises colored fillers, such as pigments, wherein said fillers are located at least at the height of the interruptions and said pigments are present in such an amount that the top layer of the substrate is visible, then this panel is also a panel according to the first aspect of the invention, with a transparent or translucent glue layer. Embodiments of this first aspect of the invention, can therefore also apply to this preferred embodiment of the second aspect, as long as not contradictory.

[39] The glue layer can comprise one or several types of glue, for example a thermoset glue or a thermoplastic glue. Examples of possible glues are aminoplast polymer glues such as urea formaldehyde glues, melamine urea formaldehyde glues or melamine formaldehyde phenolic glues. Other possible glues are polyvinyl acetate glues, polyurethane glues, poly acrylate glues, polymeric methylene difenyl di-isocyanate glues, polyvinyl butyral (PVB) glues, bio-based glues based on for example sugars, lignin, hyper branched polyamides, PUR hotmelts, polyester glues, etc. It is not excluded that the glue contains an additional hardener to improve the bonding, such hardener can be based on for example isocyanates, carbodiimides, aziridine, epoxy, etc.

[40] Preferably the glue layer is penetrated into said interruptions according to a direction perpendicular to the plane in which the panel extends. This direction is here the thickness direction of said timber layer. Because said glue layer has penetrated into said interruptions, the glue layer provides additional strength to said timber layer, making the timber layer for example more resistant to wear. Further preferably, according to said direction, the glue layer is located between an upper surface and a bottom surface of the panel. Preferably said glue layer only adheres the timber layer to the substrate, and only at the height of the interruptions, the glue layer is located higher with regard to the substrate.

[41] Preferably the glue layer penetrates at most 50 percent of the thickness of the timber layer, more preferably at most 30 percent, most preferably 10 percent. In this way the top surface of the timber layer is not negatively influenced by the glue layer. If pressing is used to produce the panel, the pressing conditions can be chosen in such a way that the glue layer only penetrates the desired percentage of the thickness of the timber layer. For example the time and/or the temperature and/or the pressure can be chosen. It is also possible to work with two pressing operations, a first milder pressing operation, a so-called prepressing, followed by a second pressing operation.

[42] In embodiments, the glue layer can penetrate at least 50 percent, or at least 70 percent, or at least 90 percent of the thickness of the timber layer, or the glue layer can penetrate the entire thickness of the timber layer. In this way the timber layer is strengthened by the glue.

[43] The panel can comprise one timber layer, but can also comprise two or more timber layers adhered to each other. If said panels comprises two or more timber layers, said timber layers are preferably arranged on top of each other in their original order and orientation in the timber piece from which they are cut, such that interruptions are located on top of each other. The one or more timber layers may or may not be compressed timber layers. The thickness of said compressed timber layer can be at least 70%, or at least 80% or at least 90% of the thickness of the original timber layer. [44] If said timber layer is directly attached to said substrate, thus without an additional glue layer, said substrate is preferably penetrated into said interruptions according to a direction perpendicular to the plane in which the panel extends. Preferably, at the height of the interruptions, the substrate is located higher. Also preferably the substrate penetrates at most 50 percent of the thickness of the timber, more preferably at most 30 percent, most preferably 10 percent. In this way the top surface of the timber layer is not negatively influenced by the substrate.

[45] In a specific embodiment the thickness of the timber layer is less than 1,5 mm, preferably at most 1 mm, more preferably at most 0.7 mm. Also preferably the timber layer is at least 0,2 mm and more preferably at least 0,4 mm. The thickness of the timber layer is preferably between 0,2 mm and 1 mm, more preferably between 0,4 mm and 0,7 mm. The thickness is here the thickness of the timber layer in the panel. It has been found that the invention is specifically useful for panels in which the timber layer is thin. The filling up of cracks/pits of thin timber layers, being thin veneer layers, with wood putty or wood filler, is more difficult than for thicker timber layers and also results in more unwanted residues of wood putty or wood filler surrounding said cracks/pits. Further sanding steps to take away such residues cannot be performed upon thin wood veneers or can only be performed in a small amount. The invention thus ensures that even with thin veneers, a desired panel is obtained.

[46] In another embodiment the timber layer is thicker than 1,5 mm. The timber layer can be thicker then 2,5 mm and the panel can then be named parquet.

[47] According to a third aspect of the invention, the invention also concerns a panel comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, and wherein said panel comprises a glue layer by which the top layer is attached to the substrate, wherein the glue layer is a stainable glue layer, wherein said glue layer is at least accessible at the height of the interruptions. This means that at the height of said interruptions, the glue layer can be stained at will in the desired color, such to have a panel with the desired appearance. This can be done in a production environment but also after said panels are placed. The latter means that the end consumer can choose which color said interruptions have, which can be desirable. One can choose for a specific staining means, that for example only reacts with said glue layer and for example not with the timber layer, such that only the interruptions get stained. When said stainable glue layer gets stained, said glue layer can comprise colored fillers, such that a panel according to the first aspect can be obtained. The embodiments described for the first aspect of the invention then also apply to this panel, after the staining of said glue layer. Before the staining is applied, said glue layer can already comprise colored fillers, and can thus already be an embodiment of the first aspect of the invention.

[48] The glue layer can comprise one or several types of glue, for example a thermoset glue or a thermoplastic glue. Examples of possible glues are aminoplast polymer glues such as urea formaldehyde glues, melamine urea formaldehyde glues or melamine formaldehyde phenolic glues. Other possible glues are polyvinyl acetate glues, polyurethane glues, poly acrylate glues, polymeric methylene difenyl di-isocyanate glues, polyvinyl butyral (PVB) glues, PUR hotmelts, polyester glues, bio-based glues based on for example sugars, lignin, hyper branched polyamides, etc. It is not excluded that the glue contains an additional hardener to improve the bonding, such hardener can be based on for example isocyanates, carbodiimides, aziridine, epoxy, etc.

[49] In a specific embodiment the glue layer is a plastic based layer which is stainable, such as a thermoplastic based layer, for example a PVC based layer, a PVB based layer or polyethylene-based layer. The said timber layer is for example laminated upon the substrate by heat pressing, such that the thermoplastic based layer melts and connects the timber layer to the substrate as such to form a panel according to the invention. Preferably said thermoplastic based layer fills up said interruptions. [50] To be stainable, said stainable glue layer can comprises stainable fillers. The stainable fillers can comprise porous particles, which can easily absorb color and can thus be easily stained. When said stainable fillers get stained, colored fillers are obtained, such that a panel according to the first aspect is obtained. The embodiments described for the first aspect of the invention therefore also apply to this panel, after the staining of said stainable fillers. Off course, before the staining, colored fillers could also be already present.

[51] The fillers can comprise wood particles, such as saw dust, wood fibers or wood chips. The fillers can be cellulosic fibers or inorganic fillers such as silicates, aluminosilicates, clays, etc.

[52] A possible example of a glue layer for the third aspect of the invention is the following: The glue layer comprises a paper sheet. The paper sheet can be a colored paper sheet of for example between 50 and 120 gsm. The color is for example black or brown. The paper sheet can also be a transparent sheet of for example between 25 and 50 gsm. Said paper sheet is impregnated with polyurethane, preferably with a transparent and water based polyurethane dispersion, and this preferably until a weight of substantially 120 gsm, in case of a colored paper sheet, or until a weight of substantially 65 gsm, in case of a transparent paper sheet. Said weight is the weight of the paper, the polyurethane and the residual moist. The residual moist is preferably lower than 10 weight percentage, more preferably lower than 7 weight percentage, this for example measured after 5 minutes at 160°C. If the residual moist is too high, this can result in local delamination and/or discoloration of the top layer. Instead of polyurethane, a melamine formaldehyde resin or another glue can be used. Further preferably a coating is applied to one side of said impregnated paper sheet, the side at the height of the top layer. This is a colored coating, preferably water based. This coating can be applied inline with the impregnation of the paper sheet. Said coating comprises preferably polyurethane, pigments and other (colored) fillers, wherein said other fillers comprise at least stainable fillers, such that the color of the panel can be changed if desired. For example the coating comprises 1 to 10 weight percentage pigments and 2 to 20 weight percentage other fillers, such as koalin, wood dust, silica, aluminosilicates, glasbeads or aluminum oxide. The average particle size of the other fillers can be between 5 and 80 micron, preferably between 5 and 50 micron.

[53] Another possible example of a glue layer is the following: The glue layer comprises a paper sheet. The paper sheet can be a colored paper sheet of for example between 50 and 120 gsm. The color is for example black or brown. The paper sheet can also be a transparent sheet of for example between 25 and 50 gsm. Said paper sheet is impregnated with polyurethane, preferably with a transparent and water based polyurethane dispersion, and this preferably until a weight of substantially 120 gsm, in case of a colored paper sheet, or until a weight of substantially 65 gsm, in case of a transparent paper sheet. Said weight is the weight of the paper, the polyurethane and the residual moist. The residual moist is preferably lower than 10 weight percentage, more preferably lower than 7 weight percentage, this for example measured after 5 minutes at 160°C. If the residual moist is too high, this can result in local delamination and/or discoloration of the top layer. Instead of polyurethane, a melamine formaldehyde resin or another glue can be used. Further preferably a coating is applied to one side of said impregnated paper sheet, the side at the height of the top layer. This can be a colored coating, and preferably the coating is water based. This coating can be applied inline with the impregnation of the paper sheet. Said coating comprises preferably polyurethane and fillers of which some are stainable fillers. For example the coating comprises 2 to 20 weight percentage fillers, such as koalin, wood dust, silica, aluminosilicates, glasbeads or aluminum oxide. The average particle size of the fillers can be between 5 and 80 micron, preferably between 5 and 50 micron.

[54] Preferably the glue layer is penetrated into said interruptions according to a direction perpendicular to the plane in which the panel extends. This direction is here the thickness direction of said timber layer. Because said glue layer has penetrated into said interruptions, the glue layer provides additional strength to said timber layer, making the timber layer for example more resistant to wear. Further preferably, according to said direction, the glue layer is located between an upper surface and a bottom surface of the panel. Preferably said glue layer only adheres the timber layer to the substrate, and only at the height of the interruptions, the glue layer is located higher with regard to the substrate.

[55] Preferably the glue layer penetrates at most 50 percent of the thickness of the timber, more preferably at most 30 percent, most preferably 10 percent. In this way the top surface of the timber layer is not negatively influenced by the glue layer. If pressing is used to produce the panel, the pressing conditions can be chosen in such a way that the glue layer only penetrates the desired percentage of the thickness of the timber. For example the time and/or the temperature and/or the pressure can be chosen. It is also possible to work with two pressing operations, a first milder pressing operation, a so-called prepressing, followed by a second pressing operation.

[56] In embodiments, the glue layer can penetrate at least 50 percent, or at least 70 percent, or at least 90 percent of the thickness of the timber layer, or the glue layer can penetrate the entire thickness of the timber layer. In this way the timber layer is strengthened by the glue.

[57] The panel can comprise one timber layer, but can also comprise two or more timber layers adhered to each other. If said panels comprises two or more timber layers, said timber layers are preferably arranged on top of each other in their original order and orientation in the timber piece from which they are cut, such that interruptions are located on top of each other. The one or more timber layers may or may not be compressed timber layers. The thickness of said compressed timber layer can be at least 70%, or at least 80% or at least 90% of the thickness of the original timber layer.

[58] In a specific embodiment the timber layer is less than 1,5 mm, preferably at most 1 mm, more preferably at most 0.7 mm. Also preferably the timber layer is at least 0,2 mm and more preferably at least 0,4 mm. The thickness of the timber layer is preferably between 0,2 mm and 1 mm, more preferably between 0,4 mm and 0,7 mm. It has been found that the invention is specifically useful for panels in which the timber layer is thin. The filling up of cracks/pits of thin timber layers, being thin veneer layers, with wood putty or wood filler, is more difficult than for thicker timber layers and also results in more unwanted residues of wood putty or wood filler surrounding said cracks/pits. Further sanding steps to take away such residues cannot be performed upon thin wood veneers or can only be performed in a small amount. The invention thus ensures that even with thin veneers, a desired panel is obtained.

[59] In another embodiment the timber layer is thicker than 1,5 mm. The timber layer can be thicker then 2,5 mm and the panel can then be named parquet.

[60] This invention also concerns, according to a fourth aspect, a method to produce a panel comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, and wherein said top layer is glued upon the substrate, such that the panel comprises a glue layer located mostly between the substrate and top layer, wherein said glue layer comprises colored fillers, wherein said colored fillers are at least located at the height of the interruptions. With a glue layer located mostly between the substrate and top layer, is indicated that said glue layer is at least located between the substrate and the top layer. Preferably at least 50%, more preferably at least 70% and most preferably at least 80% of the volume and/or the weight of the glue layer is located between the substrate and the top layer.

[61] With the aid of said method, an aesthetic panel, even though the timber layer comprises said interruptions, is obtained. With the aid of such a method, a panel according to the first aspect is obtained, wherein said panel comprises a timber layer, a glue layer and a substrate, wherein said glue layer is different from the substrate. The advantages and embodiments described for said panel according to the first aspect, also apply for this method. [62] Preferably, to glue said timber layer upon the substrate, a stack comprising said substrate, glue in an at least partly liquid form and the at least one timber layer is formed and preferably pressed, wherein said glue hardens, and wherein before or during the hardening of the glue, colored fillers are applied upon the glue to form said glue layer with colored fillers. The appliance of said colored fillers can be performed before, during, or after the formation of said stack. For example the glue can firstly be applied upon the substrate, after which the colored fillers are applied upon the glue, for example by spraying, scattering or raking, and after which the at least one timber layer is applied upon the glue. Another possibility is to firstly form the stack and then to apply the colored fillers from above upon this stack, for example by scattering the colored fillers upon the at least one timber layer. This can be done before or after a pressing step, if pressing occurs. Here the colored fillers will fall into said interruptions. Since said glue layer is accessible at the height of said interruptions, said colored fillers, when said glue is not completely hardened, will adhere to the glue. In the latter case, the colored fillers are substantially located at the height of the interruptions. This can be done before or after a pressing step, if pressing occurs. If pressing occurs, this can be done before pressing, such that the glue is sufficiently liquid and the colored fillers can attach well to the glue. The pressing can also comprise at least two pressing steps, with a first pressing step which positions the timber layer with regard to the substrate, and which does not or not completely harden the glue and a final pressing step which hardens the glue. In this latter case, the colored fillers are preferably applied between the first and the final pressing step. It is also possible to form the stack without pressing, and to scatter the colored fillers upon the stack. After this the stack can be pressed.

[63] In another embodiment, to glue said timber layer upon the substrate, a stack comprising at least said substrate, a glue impregnated paper and at least one timber layer, with said resin impregnated paper located between said substrate and said at least one timber layer, is formed and preferably pressed, wherein said glue at least partially liquifies and hardens again, and wherein before or during the hardening of the glue, colored fillers are applied upon the glue impregnated paper to form said glue layer with colored fillers. Preferably the colored fillers are applied upon the glue impregnated paper after the glue has liquified and before any hardening has occurred. Also preferably the stack is already formed when the colored fillers are applied, and the colored fillers are applied upon the timber layer, such that at the height of the interruptions the colored fillers attach to the glue. Preferably the glue impregnated paper is a resin impregnated paper, wherein preferably said resin is in an at least partially uncured form before pressing. The resin impregnated paper is preferably in a dry form when forming the stack, but still an at least partially uncured form. Preferably the pressing has at least two pressing steps, a first pressing step which positions the timber layer, the resin impregnated paper and the substrate with regard to each other and which at least partially liquifies the resin of the resin impregnated paper, and a final pressing step to cure the resin of the resin impregnated paper. The appliance of the colored fillers is preferably done between the first pressing step and the final pressing step and the colored fillers are applied upon the timber layer, for example by spraying or scattering of the colored fillers upon the timber layer such that the colored fillers can attach to the resin of the resin impregnated paper at the height of the interruptions. The pressing conditions of the first pressing step are preferably milder than the pressing conditions of the final pressing step. It is also possible to form the stack without pressing, and to scatter the colored fillers upon the stack. After this the stack can get pressed, during which the glue liquifies and the colored fillers can get attached to the glue. The glue layer can for example be an impregnated paper with an additional coating applied upon it, for example a paper impregnated with a polyurethane and an additional coating applied to it, said coating comprising polyurethane, optionally pigments and other fillers. Preferably this impregnated paper is an impregnated black or brown paper.

[64] Together with the appliance of the colored fillers, other components can be applied upon the glue layer, for example scattered upon the timber layer. For example one can also apply promoters which promote the adhesion between the colored fillers and the glue layer and/or one can apply activators which promote curing, for example UV-curing or chemical curing. [65] As alternative to pressing described above or in addition to pressing described above, other method steps can be used to cure/harden the glue layer, for example UV-curing, heat curing in for example an oven, curing with the aid of a laser, chemical curing, etc.

[66] The glue layer can comprise one or several types of glue, for example a thermoset glue or a thermoplastic glue. Examples of possible glues are aminoplast polymer glues such as urea formaldehyde glues, melamine urea formaldehyde glues or melamine formaldehyde phenolic glues. Other possible glues are polyvinyl acetate glues, polyurethane glues, poly acrylate glues, polymeric methylene difenyl di-isocyanate glues, polyvinyl butyral (PVB) glues, PUR hotmelts, polyester glues, bio-based glues based on for example sugars, lignin, hyper branched polyamides, etc. If said glue layer is a thermoplastic based layer, said glue layer can be in a solid form before the gluing of the timber layer upon the substrate. Said timber layer is then preferably heat pressed upon said glue layer, by which, under the influence of heat, said glue layer will liquify and attach to said timber layer. It is not excluded that the glue contains an additional hardener to improve the bonding, such hardener can be based on for example isocyanates, carbodiimides, aziridine, epoxy, etc.

[67] Further preferably, after applying said colored fillers, the colored fillers which have not adhered to the glue, are removed. This can be done by brushing up or with the aid of a hoover.

[68] In an alternative embodiment, the glue in its at least partly liquid form, is mixed with colored fillers as such creating a glue in which the colored fillers are homogenously blended, wherein this glue with colored fillers is used to form a stack comprising said substrate, the glue and the timber layer.

[69] Preferably the said stack is pressed in such a way that glue penetrates into said interruptions according to a direction perpendicular to the plane in which the panel extends. This direction is here the thickness direction of said timber layer. Further preferably, according to said direction, the glue layer is located between an upper surface and a bottom surface of the panel.

[70] Preferably the glue that is used to form the stack is least partially uncured, wherein after the placement of the timber layer upon the glue, curing is performed. This curing can be done in one step or in multiple steps. For example curing or partial curing can occur during the pressing of the stack. Said pressing can be done at a certain temperature beneficial for said curing or partial curing. There can also be (additional) UV curing, chemical curing, heat curing, etc. When curing is done partially by pressing and if there is additional curing, the additional curing is referred to as post curing.

[71] The timber layer can further be treated to increase the wear resistance. For example one or several wear resistant layers can be applied to the timber layer, such as for example lacquer layers and/or oil layers. Said one or several wear resistant layers are preferably applied upon the timber layer, after said timber layer is attached to the substrate, for example after the pressing.

[72] According to a fifth aspect, this invention concerns a method to produce a panel comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, and wherein said substrate comprises thermoplastic material and said timber layer is heat pressed upon the substrate, such that at the height of the timber layer the substrate melts, and the timber layer adheres to said substrate, wherein said substrate, at least at the height of the timber layer, comprises colored fillers, such that colored fillers are located at the height of the interruptions. With the aid of such a method, a panel according to the first aspect is obtained, wherein said panel comprises a timber layer and a substrate comprising thermoplastic material, wherein said timber layer is directly attached to said substrate. The advantages and embodiments described for said panel according to the first aspect, also apply for this method. The substrate, at least at the height of the timber layer, comprises colored fillers. Said substrate can already comprise said colored fillers before said heat pressing. Said colored fillers can also be applied during the production of said panel, for example before, during and/or after the heat pressing. During heat pressing the substrate melts at the height of the timber layer. Said colored fillers can adhere to said melted substrate, as such to form a substrate comprising colored fillers. For example, before pressing, colored fillers can be scattered upon the timber layer, with part of the colored fillers falling in said interruptions and thus falling upon the top surface of the substrate. During pressing the substrate melt and said colored fillers which have fallen upon said top surface, adhere to the substrate. Afterwards, the non-adhered colored fillers are removed.

[73] Together with the appliance of the colored fillers, other components can be applied upon the glue layer, for example scattered upon the timber layer. For example one can also apply promoters which promote the adhesion between the colored fillers and the glue layer.

[74] According to a sixth aspect, this invention concerns a method to produce a panel comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, wherein the substrate is a wood based board, such as a fiberboard, a particle board or a timber layer, and at least a top surface of the fiberboard is colored, wherein the timber layer is glued upon the top surface of the substrate with a transparent or translucent glue, such that the said top surface of the substrate is visible through the interruptions. With the aid of such a method, a panel according to the second aspect is obtained, wherein said substrate is a wood-based board. The advantages and embodiments described for said panel according to the second aspect, also apply for this method. With the aid of said method, a good-looking panel, even though the timber layer comprises cracks and/or voids and/or pits, is obtained.

[75] Another method to provide a panel according to the second aspect, wherein the substrate comprises thermoplastic material, is the following: a method according to a seventh aspect of the invention to produce a panel comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, wherein the substrate comprises thermoplastic material, such as PVC, PVB, PP, or PLA, and at least a top surface of the substrate is colored, wherein the timber layer is heat pressed upon the top surface of the substrate, such that said thermoplastic material, at least at said top surface of the substrate melts and attaches to said timber layer. The substrate is here visible through the interruptions and this because preferably the substrate penetrates said interruptions. Said substrate can for example comprise wood particles, such as wood dust, wood fibers or wood chips, which are glued together with the aid of a thermoplastic glue. Further said substrate can comprise pigments. Said substrate can also comprises substantially thermoplastic material, for example at least 50 percentage by weight of thermoplastic material. Alternatively, a separate glue layer can be provided to attach the top layer to the substrate.

[76] The substrate according to the sixth aspect or seventh aspect can be obtained by staining and/or painting the top surface of the substrate.

[77] Preferably, to glue a said timber layer upon a said substrate, a stack comprising said substrate, glue in an at least partly liquid form and the timber layer is formed and preferably pressed, wherein said glue hardens.

[78] The glue layer can comprise one or several types of glue, for example a thermoset glue or a thermoplastic glue. Examples of possible glues are aminoplast polymer glues such as urea formaldehyde glues, melamine urea formaldehyde glues or melamine formaldehyde phenolic glues. Other possible glues are polyvinyl acetate glues, polyurethane glues, poly acrylate glues, polymeric methylene difenyl di-isocyanate glues, polyvinyl butyral (PVB) glues, PUR hotmelts, polyester glues, bio-based glues based on for example sugars, lignin, hyper branched polyamides, etc. If said glue layer is a thermoplastic based layer, said glue layer can be in a solid form before the gluing of the timber layer upon the substrate. Said timber layer is then preferably heat pressed upon said glue layer, by which, under the influence of heat, said glue layer will liquify and attach to said timber layer. It is not excluded that the glue contains an additional hardener to improve the bonding, such hardener can be based on for example isocyanates, carbodiimides, aziridine, epoxy, etc.

[79] Preferably the said stack is pressed in such a way that glue is penetrated into said interruptions according to a direction perpendicular to the plane in which the panel extends. This direction is here the thickness direction of said timber layer. Further preferably, according to said direction, the glue layer is located between an upper surface and a bottom surface of the panel.

[80] Preferably the glue that is used to form the stack is least partially uncured, wherein after the placement of the timber layer upon the glue, curing is performed. This curing can be done in one step or in multiple steps. For example curing or partial curing can occur during the pressing of the stack. Said pressing can be done at a certain temperature beneficial for said curing or partial curing. There can also be (additional) UV curing, chemical curing, heat curing, etc. When curing is done partially by pressing and if there is additional curing, the additional curing is referred to as post curing.

[81] The timber layer can further be treated to increase the wear resistance. For example one or several wear resistant layers can be applied to the timber layer, such for example lacquer layers and/or oil layers. Said one or several wear resistant layers are preferably applied upon the timber layer, after said timber layer is attached to the substrate and also after said interruptions have obtained the desired appearance. Thus preferably after the pressing of said stack.

[82] The invention according to an eight aspect concerns a method to produce a panel comprising a top layer and a substrate, wherein the top layer comprises at least one timber layer comprising interruptions such as cracks and/or voids and/or pits, and wherein said timber layer is glued upon the substrate, such that the panel comprises a glue layer located mostly between the substrate and the top layer, and accessible at least at the height of interruptions, wherein said glue layer is a stainable glue layer. With the aid of such a method, a panel according to the third aspect is obtained. The advantages and embodiments described for said panel according to the third aspect, also apply for this method. With the aid of said method, a good-looking panel, even though the timber layer comprises cracks and/or voids and/or pits, is obtained, wherein this panel can be stained at will. With a glue layer located mostly between the substrate and top layer, is indicated that said glue layer is at least located between the substrate and the top layer. Preferably at least 50%, more preferably at least 70% and most preferably at least 80% of the volume and/or the weight of the glue layer is located between the substrate and the top layer.

[83] Said stainable glue layer can be a thermoplastic based glue layer or a thermoset based glue layer.

[84] Preferably said glue layer comprises stainable fillers. The fillers can be wood particles such as sawdust, wood fibers, wood chips. The fillers can be cellulosic fibers or inorganic fillers such as silicates, aluminosilicates and clay.

[85] This staining can be done in a production environment, but also after the installation of the panels. In the latter case, the end consumer can choose the color of the interruptions.

[86] Preferably, to glue said timber layer upon the substrate, a stack comprising said substrate, glue in an at least partly liquid form and the timber layer is formed and preferably pressed, wherein said glue hardens.

[87] The glue layer can comprise one or several types of glue, for example a thermoset glue or a thermoplastic glue. Examples of possible glues are aminoplast polymer glues such as urea formaldehyde glues, melamine urea formaldehyde glues or melamine formaldehyde phenolic glues. Other possible glues are polyvinyl acetate glues, polyurethane glues, poly acrylate glues, polymeric methylene difenyl di-isocyanate glues, polyvinyl butyral (PVB) glues, PUR hotmelts, polyester glues, bio-based glues based on for example sugars, lignin, hyper branched polyamides, etc. If said glue layer is a thermoplastic based layer, said glue layer can be in a solid form before the gluing of the timber layer upon the substrate. Said timber layer is then preferably heat pressed upon said glue layer, by which, under the influence of heat, said glue layer will liquify and attach to said timber layer. It is not excluded that the glue contains an additional hardener to improve the bonding, such hardener can be based on for example isocyanates, carbodiimides, aziridine, epoxy, etc.

[88] Preferably the said stack is pressed in such a way that glue is penetrated into said interruptions according to a direction perpendicular to the plane in which the panel extends. This direction is here the thickness direction of said timber layer. Further preferably, according to said direction, the glue layer is located between an upper surface and a bottom surface of the panel.

[89] Preferably the glue that is used to form the stack is least partially uncured, wherein after the placement of the timber layer upon the glue, curing is performed. This curing can be done in one step or in multiple steps. For example curing or partial curing can occur during the pressing of the stack. Said pressing can be done at a certain temperature beneficial for said curing or partial curing. There can also be (additional) UV curing, chemical curing, heat curing, etc. When curing is done partially by pressing and if there is additional curing, the additional curing is referred to as post curing.

[90] The timber layer can further be treated to increase the wear resistance. For example one or several wear resistant layers can be applied to the timber layer, such for example lacquer layers and/or oil layers. Said one or several wear resistant layers are preferably applied upon the timber layer, after said timber layer is attached to the substrate and also after said interruptions have obtained the desired appearance. [91] With the intention of better showing the characteristics of the invention, herein below, as an example without any limitative character, some embodiments are described, with reference to the following figures:

-figure 1 shows a simplified perspective view of a panel according to the invention;

-figure 2 shows a detail of a cross section of a panel according to the invention, wherein said panel comprises a veneer with interruptions, a glue layer and a substrate, wherein said glue layer differs from said substrate and wherein said glue layer has penetrated said interruptions;

-figure 3 shows a detail of a cross section of a panel according to the invention, wherein said panel comprises a veneer with interruptions, a glue layer and a substrate, wherein said glue layer differs from said substrate and wherein said glue layer is located almost completely below the veneer;

-figure 4 shows a cross section of a panel according to the invention, wherein the panel comprises a veneer with interruptions and a thermoplastic based substrate, wherein the veneer is directly attached to said substrate, wherein said substrate has penetrated said interruptions;

-figure 5 shows a cross section of a panel according to the invention, wherein the panel comprises a veneer with interruptions and a thermoplastic based substrate, wherein the veneer is directly attached to said substrate, wherein said substrate is almost completely below said veneer.

[92] Figure 1 shows a simplified view of a perspective view of a panel 1 according to the invention. Said panel 1 comprises a top layer 2 which is a veneer

2 with interruptions 3 such as voids/cracks/pits, and a substrate 4. Said interruptions

3 have a dark appearance. From this simplified view it is not visible how said interruptions 3 are provided with said dark appearance. Different embodiments of such a panel 1 are possible.

[93] A first option, is that the panel 1 comprises a glue layer 5, which is different from the substrate 4, wherein said glue layer 5 attaches the veneer 2 to the substrate 4. A second option is that the veneer 2 is directly attached to said substrate 4, wherein said substrate 4 forms the glue to attach the veneer 2 to the substrate 4. In the first option the glue layer 5 can or cannot comprise a sheet. For example the glue layer 5 can comprise a resin impregnated paper.

[94] In the first option, the glue layer 5 can provide said dark appearance. For this the glue layer 5 for example comprises colored fillers and/or is stained, and this at least at the height of the interruptions 3. Another possibility is that the top surface of the substrate 4 has a dark color, and the glue layer 5 is transparent or translucent, such that the top surface of the substrate 4 is visible at the height of the interruptions 3.

[95] In the second option, the substrate 4 provides said dark appearance and for this said substrate 4 is colored substrate 4 and this at least at the height of the veneer 2. The colored substrate 4 can have colored fillers and/or can be stained.

[96] Figure 1 is therefore a simplified perspective view of a panel 1 according to the first, second and third aspect of the invention. All the methods described above, are possible methods to form this panel 1 of figure 1.

[97] Figures 2 and 3 show possible cross section of said first option and figures 4 and 5 show possible cross sections of said second option. The main difference between the figures of each option, is that the substrate 4 or the glue layer 5 has or has not penetrated said interruptions 3.

[98] The present invention is in no way limited to the herein above-described embodiments; on the contrary, the invention can be realized according to various variants, without leaving the scope of the present invention, as defined by the appended claims.

Claims

1.- A panel (1) comprising a top layer (2) and a substrate (4), wherein the top layer (2) comprises at least one timber layer comprising interruptions (3) such as cracks and/or voids and/or pits, and wherein said panel (1) comprises a glue layer, for example a separate glue layer (5), by which the top layer (2) is attached to the substrate (4), wherein the glue layer comprises colored fillers, such as pigments, located at least at the height of said interruptions (3).

2.- The panel (1) according to claim 1, wherein the glue layer is penetrated into said interruptions (3) according to a direction perpendicular to the plane in which the panel (1) extends.

3.- The panel (1) according to claim 2, wherein, according to said direction, the glue layer is located between an upper surface and a bottom surface of the panel (1).

4.- The panel (1) according to any of the preceding claims, wherein the thickness of the timber layer is less than 1,5 mm, preferably less than 1 mm, more preferably between 0,2 mm and 1 mm, most preferably between 0,4 mm and 0,7 mm.

5.- The panel (1) according to any of the preceding claims, wherein the said colored fillers are substantially, and preferably only, located at the height of the interruptions (3).

6.- The panel (1) according to any of the preceding claims, wherein the colored fillers are substantially, and preferably only, located at the top side of the glue layer.

7.- The panel (1) according to any of the claims 1 to 4, wherein the colored fillers extend homogenously throughout the glue layer.

8.- The panel (1) according to any of the preceding claims, wherein the glue layer comprises a transparent or translucent base material.

9.- The panel (1) according to any of the claims 1 to 7, wherein the glue layer is substantially opaque.

10.- The panel (1) according to any of the preceding claims, wherein the colored fillers comprise pigments.

11.- The panel (1) according to any of the preceding claims, wherein the colored fillers comprise wood particles.

12.- The panel (1) according to any of the preceding claims, wherein the substrate (4) is wood-based, such as an HDF, a MDF or a particleboard, or the substrate (4) comprises at least one thermoplastic layer, wherein said glue layer is part of said substrate (4) or said glue layer (5) is and additional glue layer with respect to said substrate (4) and said top layer (2).

13.- A panel (1) comprising a top layer (2) and a substrate (4), with the top layer (2) attached to a top surface of said substrate (4), wherein the top layer (2) comprises at least one timber layer comprising interruptions (3) such as cracks and/or voids and/or pits, wherein at least the top surface of the substrate (4) is colored and wherein said top surface is visible through the interruptions (3).

14.- The panel (1) according to claim 13, wherein the substrate (4) is a woodbased board, such as a fiberboard, a particle board or a timber layer.

15.- The panel (1) according to claim 13 or 14, wherein the top surface of the substrate (4) is stained or painted.

16.- The panel (1) according to any of the claims 13 to 15, wherein the substrate

(4) comprises at least two sublayers, with a top sublayer comprising pigments, such that the top surface of said substrate (4) is colored.

17.- The panel (1) according to any of the claims 13 to 16, wherein the panel (1) comprises a transparent or translucent glue layer (5) by which the top layer (2) is attached to the substrate (4).

18.- The panel (1) according to claim 17, wherein the glue layer (5) is penetrated into said interruptions (3) according to a direction perpendicular to the plane in which the panel (1) extends and wherein preferably, according to said direction, the glue layer (5) is located between an upper surface and a bottom surface of the panel (1).

19.- A panel (1) comprising a top layer (2) and a substrate (4), wherein the top layer (2) comprises at least one timber layer comprising interruptions (3) such as cracks and/or voids and/or pits, and wherein said panel (1) comprises a glue layer

(5) by which the top layer (2) is attached to the substrate (4), wherein the glue layer (5) is a stainable glue layer, wherein said glue layer (5) is at least accessible at the height of the interruptions (3).

20.- The panel (1) according to claim 19, wherein said glue layer (5) comprises stainable fillers.

21.- The panel (1) according to claim 19 or 20, wherein the glue layer (5) is penetrated into said interruptions (3) according to a direction perpendicular to the plane in which the panel (1) extends and wherein preferably, according to said direction, the glue layer (5) is located between an upper surface and a bottom surface of the panel (1).

22.- A method to produce a panel (1) comprising a top layer (2) and a substrate (4), wherein the top layer (2) comprises at least one timber layer comprising interruptions (3) such as cracks and/or voids and/or pits, and wherein said top layer (2) is glued upon the substrate (4), such that the panel (1) comprises a glue layer (5) located mostly between the substrate (4) and top layer (2), wherein said glue layer (5) comprises colored fillers, wherein said colored fillers are at least located at the height of the interruptions (3).

23.- The method according to claim 22, wherein, to glue said top layer (2) upon the substrate (4), a stack comprising at least said substrate (4), glue in an at least partly liquid form and said at least one timber layer, is formed and preferably pressed, wherein said glue hardens, and wherein before or during the hardening of the glue, colored fillers are applied upon the glue to form said glue layer (5) with colored fillers.

24.- The method according to claim 22, wherein, to glue said top layer (2) upon the substrate (4), a stack comprising at least said substrate (4), a glue impregnated paper and at least one timber layer, with said glue impregnated paper located between said substrate (4) and said at least one timber layer, is formed and preferably pressed, wherein said glue at least partially liquifies and hardens again, and wherein before or during the hardening of the glue, colored fillers are applied upon the glue impregnated paper to form said glue layer (5) with colored fillers.

25.- The method according to claim 23 or 24, wherein after applying said colored fillers, the colored fillers which have not adhered to the glue, are removed.

26.- The method according to any of the claims 23 to 25, wherein after the formation of said stack, the said colored fillers are applied from above upon this stack, for example by scattering the colored fillers upon the at least one timber layer, preferably before the pressing of the stack.

27.- The method according to any of the claims 22 to 26, wherein said stack is pressed in such a way that glue penetrates into the interruptions (3) according to a direction perpendicular to the plane in which the panel (1) extends.

28.- The method to produce a panel (1) according any of the claims 22 to 27, wherein, to glue said top layer (2) upon the substrate (4), at least partially uncured glue is used.

29.- A method to produce a panel (1) comprising a top layer (2) and a substrate (4), wherein the top layer (2) comprises at least one timber layer comprising interruptions (3) such as cracks and/or voids and/or pits, and wherein said substrate (4) comprises thermoplastic material and said at least one timber layer is heat pressed upon the substrate (4), such that at the height of the timber layer the substrate (4) melts, and the timber layer adheres to said substrate (4) to form said top layer (2), wherein said substrate (4), at least at the height of the timber layer, comprises colored fillers, such that colored fillers are located at the height of the interruptions (3).

30.- A method to produce a panel (1) comprising a top layer (2) and a substrate (4), wherein the top layer (2) comprises at least one timber layer comprising interruptions (3) such as cracks and/or voids and/or pits, wherein the substrate (4) is a wood based board, such as a fiberboard, a particle board or a timber layer, and at least a top surface of the substrate (4) is colored, wherein the at least one timber layer is glued to the top surface of the substrate (4) with a transparent or translucent glue, such that the said top surface of the substrate (4) is visible through the interruptions (3).

31.- The method to produce a panel (1) according to claim 30, wherein said colored substrate (4) is obtained by staining and/or painting the top surface of the substrate (4).

32.- A method to produce a panel (1) comprising a top layer (2) and a substrate (4), wherein the top layer (2) comprises at least one timber layer comprising interruptions (3) such as cracks and/or voids and/or pits, and wherein said timber layer is glued upon the substrate (4) to form said top layer (2), and such that the panel (1) comprises a glue layer (5) located mostly between the substrate (4) and top layer (2) and accessible at least at the height of the interruptions (3), wherein said glue layer (5) is a stainable glue layer.

33.- The method according to claim 32, wherein said glue layer (5) comprises stainable fillers.