Panel suited for covering floors provided with a floor heating system

Abstract

The panel (1) comprises a lignocellulose based board (2); a decorative top layer (3) laminated to the lignocellulose based board; and a backing layer (4), preferably laminated to the bottom of the lignocellulose based board. The decorative top layer comprises a printed decor and a lacquer layer (5). The lacquer layer comprises an acrylate lacquer layer or a polyurethane lacquer layer. The panel (1) is less than or equal to 4 mm thick.

Description

[0001] PANEL SUITED FOR COVERING FLOORS PROVIDED WITH A FLOOR HEATING SYSTEM

[0002] The invention relates to a panel that comprises a lignocellulose based board, a decorative top layer and a backing layer. The invention also relates to floor coverings comprising such panels; and to floor systems comprising floor coverings of floors provided with a floor heating system.

[0003] It is an object of the invention to provide a panel that is well suited for covering floors that are provided with a floor heating system.

[0004] Floor heating systems are interesting from an ecological perspective. As floor heating systems can operate at relatively low temperatures they have high energy efficiency. The first aspect of the invention is a panel. The panel comprises - and preferably consists of - a lignocellulose based board; a decorative top layer laminated to the lignocellulose based board; and a backing layer. Preferably, the backing layer is laminated to the bottom of the lignocellulose based board. The decorative top layer comprises a printed decor and a lacquer layer. The lacquer layer comprises -and preferably consists of- an acrylate lacquer layer or a polyurethane lacquer layer or a polyester lacquer layer. The panel is less than or equal to 4 mm thick.

[0005] The panel of the invention is very well suited for use in floor coverings of floors equipped with floor heating systems. The panel is thin, and therefore has good thermal conductivity. The use of an acrylate lacquer layer or a polyurethane lacquer layer or a polyester lacquer is beneficial to make the thin panel of the invention and in such way that it remains flat. When curing acrylate lacquer layers, polyurethane lacquer layers or polyester lacquer layers, no condensation reaction occurs, contrary to when a melamine wear layer would be used. When condensation reactions occur in the press thermally curing the wear layer, the water resulting from the condensation reactions needs to be absorbed by the lignocellulosic fibers or particles of the lignocellulose based board. As the panel is thin, insufficient water absorbing capacity is present, which would lead to an explosion of the panel when thermally pressing the wear layer onto it. This problem is prevented by using an acrylate lacquer layer or a polyurethane lacquer layer.

[0006] Furthermore, the use of an acrylate lacquer layer, a polyurethane lacquer layer or a polyester lacquer layer prevents the occurrence of excessive shrinkage tension onto the panel when thermally pressing the panel. Excessive shrinkage tension would create cupping or other non-flatness issues of the panel.

[0007] The presence of the backing layer counteracts any deformation of the lacquer layer when thermally pressing the lacquer layer and the backing layer to the panel. This way, cupping and other non-flatness of the panel is prevented.

[0008] The features to prevent cupping and other non-flatness of the panel are the more important, as the panel is much thinner than the state-of-the art lignocellulose based panels, e.g. of the wood fiber based panels having a medium or high density fiber board as core onto which a decorative top layer is laminated.

[0009] The lacquer layer can have been applied as a 100% solids lacquer, e.g. a combination of oligomers and reactive diluents and optionally additives. An example of such 100% solid lacquers that can be used in the invention combine acrylate oligomers and acrylate reactive diluents.

[0010] The lacquer layer can have been applied as a water based dispersion, e.g. as a water based polyurethane dispersion or a water based acrylate dispersion.

[0011] Optionally, the panel comprises a - preferably resin impregnated - transparent sheet of paper carrying the lacquer layer. The resin of a resin impregnated transparent sheet of paper can be selected from the list consisting of polyurethane, acrylate, urea formaldehyde, melamine formaldehyde, polyester, or combinations thereof, e.g. combinations of acrylate and / or polyurethane on the one hand with urea formaldehyde or melamine formaldehyde on the other hand. In panels according to embodiments of the invention, a transparent sheet of paper carrying the lacquer layer can be provided on a decor layer provided by printing on the lignocellulose based board.

[0012] The panel can comprise a - preferably resin impregnated - printed sheet of paper providing the printed decor and a - preferably resin impregnated - transparent sheet of paper onto which the lacquer layer is applied. The - preferably resin impregnated - transparent sheet of paper preferably contacts the - preferably resin impregnated - printed sheet of paper.

[0013] Embodiments wherein the lacquer layer is provided on a transparent sheet of paper have the benefit that large volumes of transparent paper carrying the lacquer layer can be produced, allowing more easily mass customization of panels in combining the transparent paper provided with the lacquer layer with smaller batches of printed sheet of paper or of decor printed on the lignocellulose based board.

[0014] The panel can comprise a resin impregnated printed sheet of paper providing the printed decor and a resin impregnated transparent sheet of paper onto which the lacquer layer is applied. The resin impregnated transparent sheet of paper preferably contacts the resin impregnated printed sheet of paper.

[0015] Such embodiments have the benefit that the resin of the resin impregnated printed sheet of paper and the resin of the resin impregnated transparent sheet of paper can be optimally selected for adhesion between the different layers of the panel The resin of the resin impregnated printed sheet of paper will adhere to the lignocellulose board and to the resin impregnated printed sheet of paper. The resin of the resin impregnated transparent sheet of paper will adhere to the resin impregnated sheet of paper and to the lacquer layer.

[0016] Preferred polyester lacquers are unsaturated polyester lacquers, in which crosslinking of the double bonds occurs upon curing the lacquer.

[0017] Preferably, the top layer contacts the lignocellulose based board. Preferably, the backing layer contacts the lignocellulose based board.

[0018] The use of a lignocellulose based board means that the panel is too a large extent made of biobased material. The lignocellulose fibers, lignocellulose shives or lignocellulose particles can be recycled material.

[0019] Preferably, the panel is less than or equal to 3.5 mm thick, more preferably less than or equal to 3 mm thick.

[0020] The backing layer comprises - and preferably consists of - a resin impregnated sheet of paper. Such embodiments facilitate the integration of the backing layer in the panel. The resin can be used to laminate the backing layer to the lignocellulose based board.

[0021] It is possible that an adhesion layer is provided between the backing layer - whether or not resin impregnated - and the lignocellulose based board.

[0022] The resin of the impregnated sheet of paper of the backing layer can be selected from the list consisting of polyurethane, acrylate, urea formaldehyde, melamine formaldehyde, polyester, or combinations thereof, e.g. combinations of acrylate and / or polyurethane on the one hand with urea formaldehyde or melamine formaldehyde on the other hand.

[0023] A preferred backing layer is melamine free. Such embodiments are preferred as production problems when producing the panel are prevented, and that the flatness of the panel can be guaranteed better.

[0024] The printed decor can be provided by a printed image printed on the lignocellulose based board.

[0025] The top layer preferably comprises a resin impregnated printed sheet of paper providing the printed decor. Preferably, the resin of the resin impregnated printed sheet of paper is selected from the list consisting of polyurethane, acrylate, urea formaldehyde, melamine formaldehyde, polyester, or combinations thereof, e.g. combinations of acrylate and / or polyurethane on the one hand with urea formaldehyde or melamine formaldehyde on the other hand.

[0026] The resin can be used to laminate the resin impregnated printed sheet of paper to the lignocellulose based board. However, an adhesion layer can be added between the resin impregnated printed sheet of paper and the lignocellulosic based board.

[0027] The resin of the resin impregnated printed sheet of paper preferably does not comprise melamine nor urea. This way, condensation reactions are prevented when laminating the resin impregnated printed sheet of paper to the lignocellulose based board.

[0028] The lacquer layer can be provided on and contacting the resin impregnated printed sheet of paper.

[0029] Preferably, the decorative top layer is melamine free. This way, condensation reactions are prevented when curing the decorative to layer in a thermal pressing operation. Condensation reactions release water, which can cause serious problems in producing the thin panel of the invention. Other possible negative consequences of condensation are and non-flatness issues of the panels.

[0030] It is preferred that the resin of the resin impregnated printed sheet of paper is the same as the resin of the resin impregnated sheet of paper of the backing layer. This way, the flatness of the panel can be optimally guaranteed, as tensions in the panel are optimally balanced.

[0031] The lignocellulose based board can be selected from the list of:

[0032] - a wood fiber board;

[0033] - a wood chip board;

[0034] - a plant shives based board, e.g. a hemp shives based board, a flax shives based board or a miscanthus shives based board. When a wood chip board is used, preferred is that more than 65 wt% - and preferably more than 85 wt% - of the wood chips are finer than 830 pm

[0035] The determination of the weight percentage of the wood chip board of wood chips finer than 830 pm can be performed by a sieve analysis of the wood chips used for making the board. The sieve analysis is performed by means of sieving using a horizontal sieve shaker apparatus (e.g. the Retsch AS400) with sieves having different aperture sizes according to ISO 3310-1 :2016 “Test sieves - Technical requirements and testing - Part 1 : Test sieves of metal wire cloth”. The eccentric sieve is put in operation during 10 minutes at 2520 revolutions per minute using 250 gram chips to be tested. After these 10 minutes, the different fractions are weighed.

[0036] The lignocellulose based board preferably comprises an adhesive, wherein the adhesive bonds the lignocellulose particles of the lignocellulose based board. The adhesive preferably is a thermoset adhesive.

[0037] The adhesive preferably provides at least 4 wt% of the lignocellulose based board, more preferably at least 15 wt%, even more preferably at least 20 wt%. Such minimal amounts of adhesive are preferred from creating a panel which is resistant to water.

[0038] When the adhesive used is a methylene difenyl diisocyanate, the adhesive preferably provides at least 4 wt% of the lignocellulose based board. Such amounts are sufficient for providing a water resistant panel.

[0039] The adhesive can be selected from the list consisting of urea formaldehyde, melamine formaldehyde, isocyanate (e.g. methylene difenyl diisocyanate), acrylate, methacrylate, hyperbranched polyester amide or epoxy; or mixtures thereof.

[0040] The adhesive and / or the lignocellulose based board preferably comprises hydrophobic additives. The hydrophobic additives can be metal soap, wax, hydrophobic coated fumed silica, hydrophobic acrylate dispersion; or combinations thereof. Hydrophobic additives improve the water resistance of the panel.

[0041] The lacquer layer can comprise a urethane acrylate, a polyester acrylate, an epoxy acrylate; an unsaturated polyester; or combinations thereof.

[0042] The lignocellulose based board preferably comprises particles selected from metal particles, carbon black, mineral particles, talcum, clay, calcium carbonate, calcinated clay, aluminum oxide, copper oxide, silica, precipitated silica, titanium dioxide, kaolinite; or combinations thereof. The particles can be introduced into the lignocellulose based board via mixing the particles with the adhesive.

[0043] Such embodiments are beneficial, especially when the panel is to be used as floor covering on floor heating systems. The particles are thermally conductive, or at least have better thermal conductivity than lignocellulose. This way, the thermal conductivity of the panel is improved, making the panel more suitable for use in floor covering on floor heating systems.

[0044] The decorative top layer can be embossed, preferably comprising embossments of at least 100 pm deep, more preferably at least 200 pm deep, even more preferably at least 400 pm deep. This way, realistic wood panel imitations can be made.

[0045] The embossments preferably are at least provided in the lacquer layer.

[0046] Preferred panels comprise an edge, wherein the edge is provided with a pressed bevel. More preferably, the pressed bevel is at least 0.6 mm deep.

[0047] The printed decor can continue in the pressed bevel. If swelling of panel edges would occur, the bevels strongly reduce the visibility of the swelling. The edges of the panel are preferably provided with a coating layer or with an impregnation layer. This way, water absorption of the panel at its edges is prevented, improving the water resistance of the panel.

[0048] The edges of the panel can be straight edges, devoid of coupling parts.

[0049] The edges of the panel can be devoid of coupling parts.

[0050] The edges of the panel can be provided with profiled edges (preferably milled profiled edges), preferably for assisting correct installation of the panels.

[0051] The bottom surface of the backing layer can be embossed. An embossed bottom surface of the backing layer improves the glue down properties of the panel.

[0052] The panel can be rectangular, square or oblong.

[0053] The lacquer layer preferably is at least 100 micrometer thick, and more preferably at least 200 micrometer thick.

[0054] The lacquer layer can comprise wear and / or scratch resistance increasing particles, such as corundum particles, silicon carbide particles or diamond particles.

[0055] The second aspect of the invention is a floor covering. The floor covering comprises panels as in any embodiment of the first aspect of the invention. The panels are glued to a sub floor.

[0056] The panels have excellent thermal conductivity, making them very well suited for use in floor coverings of floors equipped with floor heating systems. As the panels are glued to the sub floor, the thermal conductivity from the floor heating system to the room covered with the floor covering is even better. The panels are preferably glued to the sub floor with a glue which is reversible The use of a reversible glue has the benefit that the panels can be easily removed, wherein the removed panels do not contain material from the sub floor. This way, recycling of the panels is facilitated.

[0057] The glue can be reversible via the application of heat. It is meant that upon application of heat to the installed panels, the glue loses its adhesive power, and the panels can be easily removed from the floor covering.

[0058] The panels can be glued to the sub floor with a glue which comprises thermally conductive particles, e.g. carbon black or metal particles. Such embodiments have the benefit that the efficiency of the floor heating systems is even more improved.

[0059] The panels can be glued to the sub floor with a glue comprising mineral fillers. The mineral fillers improve the thermal conductivity of the floor covering, increasing the efficiency of the floor heating system.

[0060] A preferred floor covering is characterized in that the panel is glued to an underlay, wherein the underlay comprises a polymer foam comprising mineral fillers.

[0061] Underlays are known to provide sound reduction when walking on floor coverings. The inventors have found that the mineral fillers in the polymer foam of the underlay improve the thermal conductivity of the floor covering, resulting in a better efficiency of floor heating systems covered with such floor coverings.

[0062] The polymer foam preferably comprises at least 70 wt% mineral fillers. Such embodiments provide floor coverings with further improved thermal conductivity.

[0063] The polymer foam can be a polyurethane foam.

[0064] The underlay preferably comprises a polymer film laminated to the polymer foam.

[0065] Preferably, the polymer film is laminated at the bottom of the underlay. The polymer film has the benefit that it prevents water penetration. In use of the floor heating, heat would be required to evaporate the water, which is negative for the efficiency of the floor heating system.

[0066] The underlay can comprise at its upper and / or at its lower side a pressure sensitive adhesive. The installation of the underlay and of the panels is facilitated this way. Thanks to the adhesive bonding achieved, the thermal conductivity of the floor covering is improved, resulting in better efficiency of floor heating systems.

[0067] The third aspect of the invention is a floor system. The floor system comprises a floor covering as in any embodiment of the second aspect of the invention. The floor system comprises a floor heating system covered by the floor covering.

[0068] The floor system of the invention provides high efficiency for the floor heating system, as the floor covering used has high thermal conductivity.

[0069] The floor heating system can be a hot water floor heating system. The hot water in the hot water floor heating system can be kept at relatively low temperature thanks to the high thermal conductivity of the floor covering. Thanks to the relatively low temperature of the hot water, the production of the hot water can be performed at high efficiency and therefore at low cost, e.g. using a high efficiency condensing gas boiler or a heat pump, e.g. using geothermal energy.

[0070] The floor heating system can be an electrical floor heating system.

[0071] The fourth aspect of the invention is a wall covering. The wall covering comprises a plurality of panels as in any embodiment of the first aspect of the invention. The panels are attached to a wall. With the intention of better showing the characteristics of the invention, hereafter, as an example without any limitative character, several preferred embodiments are described, with reference to the accompanying drawings, wherein: figure 1 illustrates an example of a panel according to the invention, figure 2 shows an example of a floor covering according to the invention, and figure 3 shows a process step in the production of a panel according to the invention.

[0072] Figure 1 shows an example of a panel 1 according to the invention. The panel consists of a lignocellulose based board 2, a decorative top layer 3 and a backing layer 4. The decorative top layer 3 is laminated to the lignocellulose based board. The backing layer 4 is laminated to the bottom of the lignocellulose based board 2. The decorative top layer comprises a printed decor and a lacquer layer 5. The lacquer layer 5 is provided by an acrylate lacquer layer, which in the example, comprises wear and scratch resistance increasing corundum particles. The panel 1 of figure 1 has thickness T 3.2 mm

[0073] The printed decor is provided by a resin impregnated printed sheet of paper 6. In the example, the resin of resin impregnated sheet of paper is a combination of acrylate and polyurethane.

[0074] In the example shows, the decorative top layer is melamine free.

[0075] The backing layer 4 consists of a resin impregnated sheet of paper. The resin of resin impregnated sheet of paper is a combination of acrylate and polyurethane. This resin is the same as the resin of the resin impregnated printed sheet of paper 6, which is beneficial for obtaining a thin, flat panel. The backing layer 4 is melamine free.

[0076] The lignocellulose based board of the example of figure 1 is a wood fiber board, more specifically a high density wood fiber board. The wood fibers are bonded by means of an adhesive, e.g. by means of 5 wt% methylene difenyl diisocyanate. Hydrophobic additives have been added to the lignocellulose based board, in order to improve the water resistance of the panel. Mineral particles - in the example of figure 1 calcium carbonate - have also been added to the lignocellulose based board.

[0077] The acrylate lacquer layer of the example is an urethane acrylate lacquer layer, applied onto the impregnated printed sheet of paper as a mixture of urethane acrylate oligomers, reactive acrylate diluents and additives (such as at least one photo-initiator and at least one thermo-initiator). The lacquer layer can be pregelled to non-tacky state by means of radiation energy, e.g. involving UV-radiation, excimer radiation or electron beam radiation. In a subsequent pressing operation, as will be explained in figure 3, the impregnated printed sheet of paper can be laminated onto the lignocellulose based board. The pressing operation allows embossing the acrylate lacquer and thermally curing the acrylate lacquer layer.

[0078] The panel of the example is rectangular and oblong. The panel 1 has four straight edges 8. The edges 8 of the panel 1 of figure 1 have a pressed bevel 9. The bevel 9 is formed in the pressing operation. As the bevel is a pressed bevel formed at the same time as laminating the top layer to the lignocellulose based board, the decorative top layer 3 covers the bevel 9.

[0079] The edges 8 of the panel 1 of figure 1 are provided with a coating layer 10 to prevent water from entering or being absorbed in the board.

[0080] Figure 2 shows an example of a floor covering 20 according to the invention. The floor covering comprises floor panels 1 according to the invention, e.g. the panels of figure 1. The panels 1 are installed using a glue layer 21. The glue of the glue layer 21 can comprise thermally conductive particles (e.g. carbon black or metal particles), or mineral fillers, or combinations thereof.

[0081] The glue layer 21 adheres the panels 1 to an underlay 23. The use of an underlay 23 is optional, as the panels can be glued directly onto the surface 24 of the room. The underlay 23 can be a polyurethane foam, preferably comprising mineral fillers. The underlay 23 can comprise a polymer film laminated to the polymer foam.

[0082] The floor covering 20 covers a floor heating system 30, e.g. tubes through which hot water is circulated.

[0083] Figure 3 shows a process step in the production of a panel according to the invention. A stack is formed of the lignocellulose based board 1, the top layer 3 (comprising the resin impregnated sheet of paper 6; the impregnated sheet of paper comprises the pregelled acrylate lacquer layer 5) and the resin impregnated sheet of paper providing the backing layer 4. A heated press comprising press elements 40, 41 is used to laminate the layers of the stack. At the same time, the surface of the panel is embossed, pressed bevels (see the panel of figure 1) can be pressed in at the edges of the panel; and the resin of the resin impregnated printed sheet of paper, the acrylate lacquer, and the resin of the backing layer can be thermally cured.

[0084] Using structured bottom element 41 of the press, the bottom surface of the backing layer can be embossed, resulting in easier glue down of the panel to a subfloor.

[0085] The present invention is in no way limited to the embodiments described as an example and represented in the figures, on the contrary it can be realized in various forms and dimensions, without leaving the scope of the invention.

Claims

Claims1 Panel, characterized in that the panel (1) comprises - and preferably consists of -- a lignocellulose based board (2);- a decorative top layer (3) laminated to the lignocellulose based board; and- a backing layer (4); preferably wherein the backing layer is laminated to the bottom of the lignocellulose based board; wherein the decorative top layer comprises a printed decor and a lacquer layer (5); wherein the lacquer layer comprises an acrylate lacquer layer, a polyurethane lacquer layer or a polyester lacquer layer; wherein the panel is less than or equal to 4 mm thick; optionally the panel comprises a - preferably resin impregnated - transparent sheet of paper carrying the lacquer layer.2.- Panel as in claim 1, characterized in that the backing layer (4) comprises - and preferably consists of - a resin impregnated sheet of paper, preferably wherein the backing layer is melamine free.3.- Panel as in claim 2, characterized in that the resin of the impregnated sheet of paper of the backing layer is selected from the list consisting of polyurethane, acrylate, urea formaldehyde, melamine formaldehyde, polyester, or combinations thereof; e.g. combinations of acrylate and / or polyurethane on the one hand with urea formaldehyde or melamine formaldehyde on the other hand.4.- Panel as in any of the preceding claims, characterized in that the top layer comprises a resin impregnated printed sheet of paper (6) providing the printed decor.5.- Panel as in claim 4, characterized in that the resin of the resin impregnated printed sheet of paper is selected from the list consisting of polyurethane, acrylate, urea formaldehyde, melamine formaldehyde, polyester, or combinations thereof, e.g.combinations of acrylate and / or polyurethane on the one hand with urea formaldehyde or melamine formaldehyde on the other hand.6.- Panel as in any of the preceding claims, characterized in that the decorative top layer is melamine free.7.- Panel as in any of the preceding claims, characterized in that the lignocellulose based board is selected from the list of:- a wood fiber board;- a wood chip board, preferably wherein more than 65 wt% of the wood chips are finer than 830 pm;- a plant shives based board; e.g. a hemp shives based board, a flax shives based board or a miscanthus shives board.8.- Panel as in any of the preceding claims, characterized in that the lignocellulose based board comprises an adhesive, wherein the adhesive bonds the lignocellulose particles of the lignocellulose based board.9.- Panel as in claim 8, characterized in that the adhesive provides at least 5 wt% of the lignocellulose based board, preferably at least 15 wt%, more preferably at least 20 wt%.10.- Panel as in claims 8 or 9, characterized in that the adhesive is selected from the list consisting of urea formaldehyde, melamine formaldehyde, isocyanate (e.g. methylene difenyl diisocyanate), acrylate, methacrylate, epoxy, hyperbranched polyester amide; or mixtures thereof.11.- Panel as in any of the preceding claims 8 - 10, characterized in that the adhesive and / or the lignocellulose based board comprises hydrophobic additives, preferably metal soap, wax, hydrophobic coated fumed silica, hydrophobic acrylate dispersion; or combinations thereof.12.- Panel as in any of the preceding claims, characterized in that the lacquer layer comprises a urethane acrylate, a polyester acrylate, an epoxy acrylate; an unsaturated polyester; or combinations thereof.13.- Panel as in any of the preceding claims, characterized in that the lignocellulose based board (2) comprises particles selected from metal particles, mineral particles, carbon black, talcum, clay, calcium carbonate, calcinated clay, aluminum oxide, copper oxide, silica, precipitated silica, titanium dioxide, kaolinite; or combinations thereof.14.- Panel as in any of the preceding claims, characterized that the decorative top layer (3) is embossed, preferably comprising embossments of at least 100 pm deep, more preferably at least 200 pm deep, even more preferably at least 400 pm deep.15.- Panel as in any of the preceding claims, characterized in that the panel comprises an edge (8), wherein the edge is provided with a pressed bevel (9), preferably wherein the bevel is at least 0.6 mm deep.16.- Panels as in any of the preceding claims, characterized in that the edges (8) of the panel are provided with a coating layer (10) or with an impregnation layer.17.- Panel as in any of the preceding claims, characterized in that the edges of the panel are straight edges, devoid of coupling parts.18.- Panel as in any of the preceding claims, characterized in that the bottom surface of the backing layer is embossed.19.- Panel as in any of the preceding claims, characterized in that the panel is rectangular, square or oblong.20.- Panel as in any of the preceding claims, characterized in that the lacquer layer is at least 100 micrometer thick, and preferably at least 200 micrometer thick.21 Floor covering, characterized in that the floor covering (20) comprises panels (1) as in any of the preceding claims 1 - 20, wherein the panels are glued to a sub floor.22.- Floor covering as in claim 21, characterized in that the panels are glued to the sub floor with a glue (21) which is reversible, e.g. which is reversible via the application of heat.23.- Floor covering as in any of the preceding claims 21 - 22, characterized in that the panels are glued to the sub floor with a glue (21) which comprises thermally conductive particles (e.g. carbon black or metal particles), or mineral fillers, or combinations thereof.24.- Floor covering as in any of the preceding claims 21 - 23, characterized in that the panel is glued to an underlay (23), wherein the underlay comprises a polymer foam - preferably a polyurethane foam - comprising mineral fillers.25.- Floor covering as in claim 24, characterized in that the polymer foam comprises at least 70 wt% mineral fillers.26.- Floor covering as in any of the preceding claims 23 - 24, characterized in that the underlay comprises a polymer film laminated to the polymer foam.27.- Floor covering as in any of the preceding claims 24 - 26, characterized in that the underlay comprises at its upper and / or at its lower side a pressure sensitive adhesive.28.- Floor system, characterized in that the floor system comprises a floor covering (20) as in any of the preceding claims 21 - 27, and that the floor system comprises a floor heating system (30) covered by the floor covering.29.- Wall covering, characterized in that the wall covering comprises a plurality of panels as in any of the preceding claims 1 - 20 attached to a wall.

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