EA047521B1 - WALL PANEL FOR FORMING A WALL COATING USING MULTIPLE PANELS - Google Patents

Description

The invention relates to a wall panel for forming a wall covering using a plurality of panels, a wall covering formed from interconnected panels and a method for laying a wall covering.

In recent decades, there have been many advances in the field of modular flooring, where multiple floor panels can be interconnected in a manner that allows for the DIY installation of high-quality flooring products. The present invention also facilitates the creation of a similar, easy-to-install technology for the field of wall paneling and wall coverings.

While wall panels and floor panels may seem similar at first glance, each has its own advantages and disadvantages. For example, floor panels (which are typically installed horizontally) are usually provided at the subfloor level, with gravity helping to keep the floor panels on the subfloor, whereas wall panels (which are typically installed vertically) do not have this advantage.

In this connection, the present invention provides a wall panel according to the preamble, which provides a wall panel for forming a wall covering using a plurality of panels, comprising a core, typically located in the centre of the core, wherein the core comprises a back side, a decorative side opposite the back side, and at least two sides of the core, comprising connecting parts for interconnecting several panels; wherein the connecting parts are designed with the possibility of being connected by an inclined movement, wherein the new panel is designed with the possibility of being positioned at an angle in a panel already forming part of the wall covering; wherein the connecting parts comprise at least one first connecting part and at least one second connecting part, located on opposite sides of the core, wherein the first connecting part comprises a laterally directed tongue, an upper intermediate part for connecting the laterally directed tongue to the core and a downwardly directed groove for receiving at least a part of an upwardly directed locking element; and wherein the second connecting part comprises a groove for receiving at least a part of a laterally directed tongue, formed by an upper lip and a lower lip extending from the core, wherein the lower lip is provided with an upwardly directed locking element located at a distance from the core, wherein the upwardly directed locking element has an inner surface facing the core, an outer surface facing away from the core, and a surface side between the inner surface and the outer surface; wherein the upwardly directed locking element is provided with a recess extending at least partially through the upwardly directed locking element, wherein the recess is accessible from the surface side of the upwardly directed locking element and extends to the opposite side of the upwardly directed locking element. Upwardly directed may be a direction towards the decorative side of the panel. The connecting parts are usually milled or profiled in the core, wherein material is removed to form the connecting parts. While the core is mentioned in relation to the connecting parts, the core may be a part of the panel that is not profiled.

In the panels described according to the invention, the decorative side may also be referred to as the upper or lower side, the rear side may also be referred to as the lower part or lower side. The panels are usually accessible in the horizontal direction from their plane, which is common in the case of floor panels. However, in comparison with them, wall panels are usually oriented with a 90-degree turn.

The tongue and groove, facing sideways, provides a relatively simple connection of panels, in which the tongue is placed (at least partially) in the groove, usually at a slight angle, and the panel is easily placed in place at an angle. This connection is intended to be very convenient to connect panels. The recess in the upward fixing element is intended for a predetermined location to attach the upward fixing element to a supporting surface or supporting structure, such as wood framing or plasterboard. The panel, for example, can be attached by driving a screw through the recess, through the upward fixing element and into the supporting structure. Instead of a screw, nails or other fasteners, fasteners or fasteners can also be used.

Thus, the recess ensures that the wall panel is fixed in place. The tongue and groove may also provide additional fixation of the wall panels. When the tongue is located in the groove, the tongue and the groove may be in contact, preventing the panels from becoming disengaged. In addition or alternatively, the inner surface of the upwardly directed locking element may be configured to contact the side of the sideways directed tongue facing the core or the proximal side of the sideways directed tongue. The inner surface of the upwardly directed locking element and the proximal side of the sideways directed tongue may be intended to be fixed in the plane of the panels, while the proximal side of the sideways directed tongue and the groove may be intended to be fixed perpendicular to the plane of the panels, in

- 1 047521 at least in a connected state. In this way, the panels can be interconnected and also fixed to the supporting structure, preventing the wall covering from coming off the wall. The inner surface of the upwardly directed fixing element can thus comprise a first fixing surface, and the side of the sideways directed tongue facing the core can comprise a second fixing surface, wherein the fixing surfaces interact to ensure fixation of the panels in the connected state. Alternatively or additionally, the side of the sideways directed tongue facing the decorative side can comprise a third fixing surface, and the side of the upper lip facing away from the decorative side can comprise a fourth fixing surface, wherein the fixing surfaces interact to ensure fixation of the panels in the connected state.

The recess may be provided with beveled edges, wherein the recess preferably has a substantially truncated cone shape in cross-section, widest on the decorative side, tapering toward the back side, or a substantially trapezoidal cross-section. The beveled edges may be intended to guide the fastening elements into the desired position of the upwardly directed locking element.

Preferably, the recess is located in the center of the upwardly directed locking element, in particular between the inner surface and the outer surface of the upwardly directed locking element. In this way, the same number of upwardly directed locking elements, or not recessed, remain on both sides of the recess, which provides a structure on both sides of the recess and a stronger panel. The upwardly directed locking element usually has an increased thickness compared to other structural elements of the locking element. In this way, it has a larger base portion and more material is available to accommodate the recess, which leads to a stronger structure overall.

The recess may extend up to a maximum of half of the upwardly directed fixing element. The recess may thus have a lower side or lower surface located up to a maximum of half of the upwardly directed fixing element. Due to the fact that the recess extends up to a maximum of half of the thickness of the upwardly directed fixing element, a sufficient amount of material remains below the recess between the recess and the back side.

The recess in the upwardly directed fixing element may be trapezoidal. The recess may also be provided with a second recess or depression, preferably in the middle or center of the recess. The second recess may be used to guide fastening elements, such as nails or screws, to the middle of the recess (and thus into the second recess). The second recess may be at most half the size or width of the recess, preferably about one third the size or width of the recess.

At least a portion of the side of the sideways tongue facing away from the core and/or at least a portion of the groove between the upper and lower lips may be partially rounded. In particular, during tilting of the panels, the rounded surfaces or transitions provide a relatively smooth tilting movement that does not interfere with the abrupt transition in the panel materials.

In the connected state, between the side of the sideways tongue facing the back side and the lower lip, there may be an intermediate space, and the intermediate space narrows from the upwardly directed locking element to the core. Such an intermediate space between the lower lip and the sideways tongue provides additional flexibility when connecting panels, and forms an intermediate space for collecting material that may be subject to shearing by the lower lip or the sideways tongue during connection. The side of the sideways tongue facing the back side and the lower lip may not be in contact, and in the connected state, contact is only between the side of the sideways tongue facing the core and the inner surface of the groove. The lack of necessity for the back side of the sideways tongue and the lower lip to be in contact additionally provides greater flexibility and additional processing tolerances.

The width of the upwardly directed locking element may be smaller compared to the width of the upper intermediate part, so that preferably in the connected state there is an intermediate space between the outer surface of the upwardly directed locking element and the core of the other panel. The width is usually a direction in the plane of the panels. The intermediate space between the upwardly directed locking element and the core increases the tolerances during production (while the panels can still be connected), and ensures a relatively simple connection of the panels, without the need to deform the connecting parts during the connection.

The first connecting part may comprise a first upper contact surface between the decorative side and the sideways tongue, and the side of the upper lip facing away from the core may comprise a second upper contact surface, wherein the first and second upper contact surfaces are arranged so as to be in contact at least partially in the connected state. The contact surfaces are surfaces facing

- 2 047521 decorative side of the core of the panels in the connected state, which are in contact. The first and/or second contact surfaces may, for example, comprise an upper locking element, wherein both contact surfaces preferably comprise upper locking elements that are designed to interact in the connected state to ensure locking in one or more directions. The upper contact surface may extend over a distance that is at least 0.1 times smaller than the thickness of the panel, preferably at least 0.15 times smaller than the thickness. In place, the upper contact surfaces may be surfaces that work against gravity. A large surface area can be used to distribute the load and prevent the occurrence of peak stress.

The first and/or second connecting parts may comprise a bevel or chamfer located on the decorative side of the panel. The bevel is usually represented by chamfered surfaces, which are inclined from the upper contact surfaces to the decorative surface of the panels. When two connected panels are provided with such chamfered surfaces, these surfaces are aligned and form a V-shaped recess. When the surfaces are not inclined or chamfered, but are preferably square or rectangular, a U-shaped recess can be made, either by only one panel or by a combination of two panels. In a particular embodiment of the invention, only one of the first and second connecting parts is provided with a bevel or chamfered surface. It is preferable that the connecting part in the position in the wall covering is directed upwards. Any moisture, liquid or raindrops that may be on the decorative side of the panel are then directed away from the surface of the joint between the two connected panels.

The core may comprise a thermoplastic material, in particular a foamed or unfoamed thermoplastic material or PVC, polypropylene, polyethylene or polyurethane and/or one or more fillers such as calcium carbonate or a wood material, such as MDF, HDF or wood-plastic material. The core may also comprise wood-based foam or pressed wood.

The specific core material selected may be filled with a thermoplastic with at least one filler such as calcium carbonate or another mineral filler. Plastic materials that are suitable for forming the base layer may include plastics made of polyurethane, copolymers of polyamide, polystyrene, polyvinyl chloride (PVC), polypropylene and polyethylene, all of which have good processing properties during molding. PVC materials are chemically stable, corrosion-resistant and have excellent fire-retardant properties. Preferably, chlorinated PVC (CPVC) and/or chlorinated polyethylene (CPE) and/or another chlorinated thermoplastic material is/are used to further increase the hardness and rigidity of the base layers and the panels as such. The plastic material may not contain any plasticizer to increase the desired rigidity of the base layer, which, in addition, is also environmentally friendly. At least one filler may be selected from the group consisting of: talc, chalk, wood, calcium carbonate, titanium dioxide, calcined clay, porcelain, (another) mineral filler and (another) natural filler. The filler may be formed by fibres and/or may be formed by dust-like particles. In this case, the term dust is understood to mean small dust-like particles (powder), such as wood dust, bark dust or non-wood dust, such as mineral dust, stone dust, in particular cement.

The core layer can be made of a composite of at least one polymer and at least one non-polymer material. The core layer composite preferably contains one or more fillers, wherein at least one filler is selected from the group consisting of: talc, chalk, wood, calcium carbonate, titanium dioxide, calcined clay, porcelain, (another) mineral filler and (another) natural filler. The filler can be formed by fibers and/or can be formed by dust-like particles. In this case, the term dust is understood to mean small dust-like particles (powder), like wood dust, bark dust or non-wood dust, like mineral dust, stone dust, in particular cement. The average particle size of the dust is preferably in the range from 14 to 20 microns, more preferably from 16 to 18 microns. The main role of this kind of filler is to provide sufficient hardness to the core layer and the parallelogram/rhombic tile(s) as such. This will ensure that the tiles, including their usual relative sensitivity to damage of the pointed tops, can realize the chevron pattern in a relatively reliable and durable way. In addition, the kind of filler will also generally increase the impact strength of the core layer and the tile(s) as such. The weight content of this kind of filler in the composite is preferably in the range of 35 to 75%, more preferably 40 to 48%, in the case where the composite is a foamed composite, and more preferably 65 to 70% in the case where the composite is a non-foamed (rigid) composite.

The sideways tongue and groove may be designed to apply a clamping force when connected to compress the two connected panels together. Such a

- 3 047521 The pressing force pushes the connected panels together, improving the connection and therefore increasing, for example, the water resistance of the waterproofing properties of the panels.

The groove may comprise a channel extending from the groove to the back of the wall panel. Such a groove may be used to drain water or other liquids that may enter the connecting parts and grooves in particular. In particular, when the groove is on the side of the panel that is directed upwards in place, the groove may be a part of the connecting parts that is located at the lowest point and is thus naturally inclined to collect liquid, water or other spilled material. The channel extending to the back or back of the panels provides such material or liquid with the opportunity to leave the connecting parts.

The panel can be elongated and adapted to be horizontally positioned to form part of a wall covering, wherein the first and second connecting parts are preferably arranged on the long sides of the panel, and/or wherein the other two opposite sides of the wall panel are optionally provided with a third and fourth connecting parts, preferably adapted to be connected by the same tilting movement as the first and second connecting parts. Such panels can be used to be laid from side to side, for example, in a room. Such panels can be about 1.5-2.5 meters wide, in particular about 1.8 meters wide, and any number of them (mutually connected) can be used to cover the width of a room or the outer surface of a building.

The panel can also be elongated and designed to be vertically positioned to form part of a wall covering, wherein the first and second connecting parts are preferably located on the long side of the panel, and/or wherein two other opposite sides of the wall panel are provided with connecting parts. Such panels can, for example, extend from the floor to the ceiling of a room.

The panel may be elongated, with the first and second connecting parts located on the long side of the panel, and with a plurality of recesses along the long side, preferably evenly distributed along the long side. The recesses may be used to connect the panels to the supporting structure or wall. The more recesses, the more options for connecting, which increases the number of options when laying the panels. In addition, this can provide more connections between the panels and the supporting structure or wall, which increases the stability or rigidity of the formed wall covering.

Thus, the other sides compared to the side with the first and second connecting parts can also be provided with connecting parts. These connecting parts can be the same connecting parts compared to the first and second connecting parts, or these connecting parts can be the third and fourth connecting parts, preferably designed to be connected by a downward movement, which can be the same angular movement used for tilting in the first and second connecting parts. Preferably, the third connecting part comprises an upwardly directed tongue, at least one upwardly directed side surface lying at a distance from the upwardly directed tongue, and an upwardly directed groove formed between the upwardly directed tongue and the upwardly directed side surface, wherein the upwardly directed groove is configured to accommodate at least a portion of the downwardly directed tongue of the fourth connecting part of the other panel, wherein the side of the upwardly directed tongue facing the upwardly directed side surface is the inner surface of the upwardly directed tongue, and the side of the upwardly directed tongue facing away from the upwardly directed side surface is the outer surface of the upwardly directed tongue; wherein the fourth connecting portion comprises a downwardly directed tongue, at least one downwardly directed side surface lying at a distance from the downwardly directed tongue, a downwardly directed groove formed between the downwardly directed tongue and the downwardly directed side surface, wherein the downwardly directed groove is configured to accommodate at least a portion of the upwardly directed tongue of the first connecting portion of the other panel, wherein the side of the downwardly directed tongue facing the downwardly directed side surface is an inner surface of the downwardly directed tongue, and the side of the downwardly directed tongue facing away from the downwardly directed side surface is an outer surface of the downwardly directed tongue; wherein the outer surface of the downwardly directed tongue and the upwardly directed side surface simultaneously comprise an upper contact surface near, or on, or next to, or towards the upper side of the panel, wherein said contact surfaces extend vertically at least partially and preferably completely, and wherein the upper contact surface of the outer surface of the downwardly directed tongue of said panel is configured to engage with the upper contact surface of the downwardly directed side surface of an adjacent panel in the connected state of said panels, wherein the adjacent upper contact surfaces of both the downwardly directed tongue and the upwardly directed side surface comprise an inclined contact surface, wherein the inclined contact surface of the downwardly directed tongue of said panel is configured to engage the inclined contact

- 4 047521 of the upwardly directed lateral surface of the adjacent panel in the connected state of said panels, wherein each vertical portion of the upper contact surface and each adjacent inclined surface together form an angle (a) from 100 to 175 degrees; wherein the adjacent inclined contact surface of the downwardly directed tongue comprises an outer surface located below the inclined contact surface of the downwardly directed tongue, and wherein the adjacent inclined contact surface of the upwardly directed lateral surface comprises an inner surface located between the inclined contact surface of the downwardly directed lateral surface, wherein the outer and inner surfaces extend substantially parallel and extend at least partially in the vertical direction; wherein in the connected state of the adjacent panel there is an intermediate space between at least part of the outer surface of said panel and at least part of the inner surface of the adjacent panel.

Preferably, the panels or connecting parts of the panels are designed in such a way that in the connected state they exert a certain locking force, pressing the panels against each other. Such a locking force can be achieved, for example, by a clamping configuration or by slightly increasing the size of one connecting part compared to the other. This creates a force in the plane of the floor panel. This locking force preferably presses the panels against each other in the main plane of the panels and thus presses the upper contact surfaces against each other, wherein this pressing improves the connection between the panels and preferably creates a watertight seal between the panels.

There is an inclined contact surface adjacent to the upper contact surfaces and usually immediately adjacent to them or immediately below them. On the inclined surfaces the panels are in contact, creating a joint or seal between the panels. The inclination is preferably such that when looking at the downward tongue, the inclined surface extends outward, and when looking at the upward side surface, the inclined surface extends inward. The angle of the inclination makes it such that the downward tongue thus has a projecting part and the upward side surface has a recessed part, which in the engaged state are in contact and thus provide a locking effect. The inclination also creates a small labyrinth, improving the watertight properties of the joint.

The downwardly directed tongue adjacent to the inclined contact surface, usually immediately adjacent to or immediately below it, comprises an outer surface. This outer surface may be, for example, the outermost surface of the downwardly directed tongue or the surface of the outer tongue that is farthest from the downwardly directed side surface. Similarly, the upwardly directed side surface adjacent to the inclined contact surface, usually immediately adjacent to or immediately below it, comprises an inner surface. Between the inner surface and the outer surface there is a space. This space is intended to prevent any force acting on or by means of the panels from pressing the panels together anywhere other than at the upper contact surfaces and/or the inclined contact surfaces. If the inner and outer surfaces were in contact, they could interfere with the contact of the upper contact surfaces, which would adversely affect the watertight properties of the joint. At the top, at the upper contact surfaces and at the inclined contact surfaces, the goal is to create a connection between the panels, while below these contact surfaces the goal is to avoid such a connection. The upper contact surfaces (in the connected state) can be in contact to form a plane or an internal vertical plane.

Thus, a portion of the downwardly directed tongue may extend beyond the internal vertical plane, wherein said portion may have a substantially trapezoidal or wedge-shaped form. Such a form allows the portion, when subjected to any locking, connecting or other force in the plane of the panels, to wedge into the space provided in the upwardly directed side surface, and also provides a strong portion capable of withstanding forces to create a tight connection between the panels. This, in turn, improves the watertight properties of the connection between the panels.

The recess in the upwardly directed fixing element may form a recessed groove running along one side of the wall panel, preferably the long side of the extended panel. The groove may be considered as a large number of adjacent recesses, together forming a preferably continuous groove. Such a groove is intended for an infinite number of fastening element options, anywhere along the panel.

The lower lip may extend behind the upper lip along a distance that is at least 2 times, preferably at least 3 times, more preferably about 4 times the thickness of the wall panel. Thus, a relatively long lower lip is proposed in comparison with a relatively thin panel. The wall panels according to the invention can, for example, be advantageously used for covering existing walls, whereby there may be no structural components or load-bearing components. Such panels can be made relatively thin, which

- 5 047521 saves material and simplifies the placement of these panels. In addition, the protruding part provides a guiding surface during installation. The thickness of the upwardly directed fixing element can be about half the thickness of the wall panel. Thus, the upper side (or the side facing the decorative side of the panel) can be located about half in the thickness ratio, which ensures a balanced change in thickness along the profile of the connecting part, preventing the formation of too many weak points in the connecting part.

The distal end of the upper lip may form a joint vertical plane, and the lower lip extends beyond said joint vertical plane. In the connected state, preferably, the distal end of the upper lip and the upper contact surface of the sideways tongue are in contact. In contact, the sideways tongue may extend behind the joint vertical plane or extend behind the upper contact surface of the sideways tongue, less than half the thickness of the panel. Or, in contact, the sideways tongue may extend behind the joint vertical plane, or extend behind the upper contact plane of the sideways tongue.

In the connected state of two panels, there may be an intermediate space between the upper intermediate portion of the first panel and the upwardly directed locking element of the second panel, at least over the entire width of the upwardly directed locking element, wherein the intermediate space continues between the distal end of the upwardly directed locking element of the second panel and the core of the first panel. The intermediate space between the upper intermediate portion and the upwardly directed locking element serves several purposes. Firstly, it provides tolerances during milling or profiling so that the panels can be interconnected even if the profiling is not perfect. Secondly, such an intermediate space can be used to collect loose particles, such as particles of core material, released from the panels during the connection. Thirdly, it provides additional space at the top of the recess for accommodating fastening elements, such as screws or nails, which may, possibly, partially protrude from the recess after the connection.

The upwardly facing fixing element on the back side opposite the surface may contain an adhesive layer, such as a thin layer of glue, to temporarily attach the wall panel to the supporting surface. By temporarily fixing the wall panel in place during installation, the installer will have his hands free to install the wall panel without fear of the panel falling.

The adhesive layer may impart adhesive properties sufficient to ensure removable attachment of the panel to a suitable supporting surface. The adhesive properties of the adhesive of the adhesive layer are applicable at room temperature (20°C) or at least in the temperature range of 15-25°C. Thus, the adhesive properties are applicable for the most common temperatures at which the laying of panels is intended. For a wider application, it is preferable when the adhesive properties are applicable in the temperature range from 0°C to 50°C.

The adhesive layer may be a continuous or discontinuous layer. The adhesive layer may be formed by a plurality of interconnected and/or spaced adhesive zones, such as adhesive dots or adhesive strips. It may be assumed that a plurality of adhesive layers are used. In this case, it may be assumed that at least two adhesive layers (parallel) are used one above the other and/or located in the same plane.

In the panel according to the invention, it is preferable that the adhesive or adhesive layer is located on the edges and/or corners of the lower or back surface of the panel, and preferably on at least 50% of the entire lower surface of the panel. In this way, the adhesive or adhesive layer, in particular, counteracts curling at the corners and edges of the panel.

In another preferred embodiment of the panel according to the invention, the adhesive of the adhesive layer is designed to provide an acceptable adhesive strength for a suitable support surface, which is less than 15 MPa, preferably less than 10 MPa. Such an acceptable adhesive strength ensures that the panel, when attached to a suitable support surface, has an attractive force that allows an average user to tear the panel off the support surface to which it is attached with moderate force. In the panels according to the invention, it is preferable that the adhesive properties of the lower surface are maintained for at least 5 years, preferably at least 10 years.

In the panels according to the invention, it is particularly preferred that the adhesive used in the adhesive layer is a pressure sensitive adhesive (PSA), preferably of the release type. PSAs are ready-to-use adhesives and are viscous. They are mainly used as a film for flexible materials. A special feature of these adhesives is that they do not harden to form a solid material, but remain viscous. They therefore occupy a special place in the group of adhesives that bond by means of a physical mechanism. For the production of pressure sensitive adhesive systems, the adhesives can be dissolved in organic solvents (e.g. natural rubber, acrylates), they can also be in liquid dispersions.

- 6 047521 (e.g. dispersions of acrylates) or may be solvent-free melts (pressure-sensitive melts).

The basic composition of PSA contains a base polymer, adhesive resin and plasticizer with additional additives to impart special properties.

The actual adhesion with pressure sensitive adhesives is due to intermolecular interactions. Pressure sensitive adhesives are usually still in a viscous liquid state in the final bond. The viscosity of the PSA therefore has a direct influence on the adhesive strength. In this context, an important distinction can be made between peelable and permanent adhesives.

The group of pressure sensitive adhesives, which have a lower viscosity, have a substantially low adhesive strength so that the glued object can be detached again after use. These types of PSA are viscous and have an unlimited time after opening, which means that they can be bonded to another substrate almost permanently.

In addition, in the panel according to the invention, it is preferable that the adhesive of the adhesive layer is a warm hot melt adhesive and/or a hot melt adhesive (HMPSA), preferably of the release type. HMPSA are a specific type of PSA and are based on thermoplastic adhesives. Likewise, HMPSA are characterized by the fact that they do not completely harden and remain permanently adhesive. This ensures an excellent adhesive bond, even when the adhesive is cold. The required contact pressure is key to creating a sufficient coating between the objects to be joined by means of HMPSA.

HMPSA retains the ability to form a strong bond under light pressure at room temperature. A preferred example of HMPSA is PSA-based polyacrylate.

With particular preference, in the panel according to the invention, the adhesive comprises one or more types of thermoplastic elastomers, such as styrene block copolymers (SBC), ethylene vinyl acetates (EVA), polyacrylates and/or amorphous polyolefins (APO). These ideally suitable thermoplastic elastomers can be modified with different types of tackifiers (natural and synthetic resins) in order to achieve the specific required adhesive properties. In the context of the invention, HMPSA preferably comprises one or more types of SBC. Such HMPSA is permanently viscous at room temperature and provides good bonding strength under light finger pressure.

In a preferred embodiment of the panel according to the invention, at least one additional layer is located between the core and the adhesive layer. This additional layer may be a backing layer rigidly connected to the underside of the core, wherein the applied adhesive layer, preferably a PSA layer, is applied to the underside of the backing layer, but wherein said adhesive layer, in particular said PSA layer, may also be included in said additional layer.

In this case, it is preferable that the underlayment comprises or consists of an elastic layer, which preferably has a foamed structure having open and/or closed pores. In this way, the elastic properties of the underlayment ensure that the panel adapts to any irregularities on the supporting surface to which it is applied. In addition, the foamed structure of the underlayment can further contribute to the attachment and detachment characteristics of the lower surface of the panel.

Preferably, the additional layer, in particular the backing layer, is at least partially made of nylon 6 (or polycaprolactam), and is a semi-crystalline polyamide, in particular nylon 6 fibres. More preferably, this layer is a perforated and/or open layer and provides an adhesive layer, during production, for penetrating the additional layer, and which can even provide the use of said adhesive layer for gluing the perforated and/or open additional layer to the core. In this case, a suitable adhesive is, for example, a PSA-based polyacrylate. The perforated and/or open layer is usually formed by means of a woven and/or non-woven layer. Alternatively, the additional layer (or backing layer), in particular the elastic layer, preferably comprises at least one material selected from the group consisting of: EVA, polyurethane (PU), polyethylene (PE), polypropylene (PP), polystyrene (PS), PVC, rubber or mixtures thereof. In addition, the elastic layer may contain a filler, in particular talc, chalk, wood and/or calcium carbonate.

Typically the elastic layer has a thickness in the range from 0.1 to 6 mm.

It is possible that the elastic underlayment layer forms (together with the adhesive layer) the lower surface of the panel. In this case, it is preferable if a plurality of (surface) suction holes are formed in at least the lower surface of said elastic layer, ensuring rapid attachment of the panel to the supporting surface and detachment from it. Preferably, the elastic underlayment layer is made of an anisotropic material. Preferably, a plurality of surface suction holes are formed in at least the lower surface of said elastic layer,

- 7 047521 wherein the surface suction holes are open in the direction facing away from the base and are substantially closed in the direction facing the base. Accordingly, these surface suction holes form isolated cavities. Typically, the surface suction holes together form a void imprint (a surface area with voids), wherein the material on the lower surface of the elastic layer between said surface suction holes forms a material imprint (a solid surface area). Preferably, the ratio of the surface area between the void imprint and the material imprint is at least 4, preferably at least 5, more preferably at least 6, thereby ensuring a quick and relatively strong attachment of the panel to the supporting surface, while maintaining ease of removal of the panel from said supporting surface. An essential advantage of the panel according to the invention is that, due to the adhesive backing quick-release structure, the panel is designed to be quickly attached to a supporting surface in a stable and durable manner, whereby the panel can also be detached from said supporting surface in a quick and easy manner, without leaving any traces behind. These properties provide the panel, in particular said panel, with good dimensional stability, good laying properties on a flat surface and flexibility for easy attachment and detachment of the panel to or from a preferably non-porous and substantially flat supporting surface, such as a floor, a wall or even a ceiling. The lower surface of the elastic layer is not provided with adhesive and preferably does not contain adhesive or other chemical adhesives. The adhesive properties of the lower surface of the elastic layer are a consequence of the presence of small suction holes (micro-holes, shell-shaped cavities and/or hemispherical micro-spaces having a suction effect). During installation, the panel to be installed is pressed against the supporting surface, which will displace air from the suction holes, wherein the annular edges of the suction holes and/or the elastic material of the lower surface located between the suction holes form a substantially hermetic seal between the lower surface of the elastic layer and the supporting surface. After the downward force applied to the installed panel is removed, a vacuum (pressure below atmospheric pressure) will be formed inside the suction holes, causing the panel to be attracted to the supporting surface and held thereon. Consequently, the panels will be significantly less susceptible to twisting and will be stabilized relative to the supporting surface until the suction force exceeds the force applied to the panel opposite to the attracting force, for example during dismantling. Since no chemical adhesive (glue) is used, the panel according to the invention can be efficiently manufactured using a flow production method. The panel according to the invention is preferably a panel characterized in that the pile threads can be made from a number of natural or synthetic fibers. However, many types of threads are made differently, with two types of threads commonly used: twist and fiber. The threads may be made of nylon, but other suitable synthetic threads such as polyester, polypropylene, acrylic, or blends of these may be used. The panel may be either rigid or flexible. It is possible for the backing to contain no threads or fibers.

The elastic layer is designed to demonstrate the principle of hard pressing, easy release, which can be easily understood as follows. When hard pressing in the desired direction, less elastic energy can be stored in the material (just as a hard spring can store less energy compared to a soft spring), which results in a lower rate of energy release to expel random crack-like defects caused by the unevenness of the supporting surface. On the other hand, much more elastic energy can be stored in the material when lightly pressing, especially when the material is largely anisotropic, which results in a much higher rate of energy release to expel the unevenness of the supporting surface caused by crack-like defects.

Preferably, substantially the entire lower surface of the elastic layer is provided with suction holes. This usually improves and increases the overall suction effect that can be realized during the laying of the panel on the supporting surface. Although the size of the suction holes can be uniform, wherein the suction holes can be, for example, stamped, punched and/or mechanically applied to the lower surface of the elastic layer, it is usually preferable that the size of the suction holes varies over the entire lower surface of the elastic layer, which is ensured, for example, by the elastic layer being formed by elastic foam. The elastic foam can have closed pores (cavities) and/or open pores (cavities). Usually, pores of different sizes are present in the foam. In one embodiment, the elastic layer is made of a foamed material consisting of EVA, which is a copolymer of ethylene and vinyl acetate, rubber, PU, PE, PP, PS, (plasticized) PVC or mixtures thereof. The elastic layer may optionally contain components such as a filler, such as chalk, talc, sand, fibre, wood, mineral and/or carbon; a foaming agent, such as azodicarbonamide, a binder, such as dicumyl peroxide, a foaming agent, such as zinc oxide; and/or a colourant. Preferably, the elastic layer of the panel according to the present invention provides a material similar to pe

- 8 047521 noresin, in terms of softness and flexibility. The material has impact strength at low temperatures, resistance to stress cracking, water-repellent properties, hermetic sealing properties and foam recovery after compression. The underlayment may comprise, for example, a non-woven fabric, a woven fabric, a non-woven polyester fabric, a polypropylene fabric, a glass fiber fabric or a fabric fabric, or a combination thereof.

The panels according to the invention are, for example, at least partially made of magnesium oxide or based on magnesium oxide. The panel according to the invention may comprise: a core having an upper and a lower side, a decorative upper structure (or upper section) attached directly or indirectly to said upper side of the core, wherein said core comprises: at least one composite layer comprising: at least one composition based on magnesium oxide (magnesia) and/or magnesium hydroxide, in particular magnesia cement. Particles, in particular particles based on cellulose and/or silicone, may be dispersed in said magnesia cement. Optionally, one or more reinforcing layers, such as glass fibre layers, may be embedded in said composite layer. The core composition may also contain magnesium chloride, resulting in magnesium oxychloride cement (MOC), and/or magnesium sulfate, resulting in magnesium oxysulfate cement (MOS).

It has been found that the use of a composition based on magnesium oxide and/or magnesium hydroxide and, in particular, magnesia cement comprising MOS and MOS significantly improves the flammability (non-combustibility) of the decorative panel as such. In addition, the relatively fire-resistant panel also has a significantly improved dimensional stability under temperature fluctuations during normal use. Magnesia cement is a cement based on magnesia (magnesium oxide), in which the cement is the product of a chemical reaction in which magnesium oxide acts as one of the reactants. In magnesia cement, magnesia may still be present and/or has undergone a chemical reaction in which another chemical bond is formed, as will be explained in more detail below. Additional advantages of magnesia cement compared to other types of cement are presented below. The first additional advantage is that magnesia cement can be produced in a relatively energy-efficient and therefore cost-effective manner. In addition, magnesia cement has relatively high compressive and tensile strength. Another advantage of magnesia cement is that this cement has a natural affinity for - usually inexpensive - cellulose materials such as wood powder from plant fibres (wood dust) and/or wood chips; this not only improves the bonding of magnesia cement, but also results in a lower mass and greater sound insulation (damping). Magnesium oxide in combination with cellulose and, optionally, clay forms magnesia cements that are permeable to water vapour; this cement does not deteriorate (rot) because this cement effectively displaces moisture. An additional advantage of magnesia cement is that it has a relatively low pH compared to other types of cement, which together ensures greater durability of the glass fibres both as dispersed particles in the cement matrix and (in the form of glass fibres) as a reinforcing layer, and, in addition, allows other types of fibres to be used in a durable manner. An additional advantage of the decorative panel is that it is suitable for both interior and exterior use.

As mentioned, magnesia cement is based on magnesium oxide and/or magnesium hydroxide. Magnesia cement as such may not contain magnesium oxide, depending on the additional reactants used to produce magnesia cement. In this case, for example, it is likely that magnesia as a reactant is converted to magnesium hydroxide during the production of magnesia cement. Therefore, magnesia cement as such may contain magnesium hydroxide. Magnesia cement usually contains water, in particular hydrated water. Water is usually used as a binder to create a strong and cohesive cement matrix.

The magnesia-based composition, in particular magnesia cement, may contain magnesium chloride (MgCl ₂ ). Generally, mixing magnesia (MgO) with magnesium chloride in an aqueous solution produces magnesia cement containing magnesium oxychloride (MOC). The binding phases are Mg(OH)2, 5Mg(OH)2-MgCl2-8H2O (Form 5), 3Mg(OH)2-MgCl2-8H2O (Form 3), and Mg2(OH)ClCO3-3H ₂ O. Form 5 is the preferred phase because this phase has excellent mechanical properties. Compared with other types of cement, such as Portland cement, MOC has excellent properties. MOC does not require wet curing, has high fire resistance, low thermal conductivity, good abrasion resistance. MOC cement can be used with various aggregates (additives) and fibers with good adhesion. It can also receive various types of surface treatment. MOC develops high compressive strength for 48 hours (e.g. 8000-10000 psi). The increase in compressive strength occurs at the early stage of curing - the 48-hour strength will be at least 80% of the ultimate strength. The compressive strength of MOC is preferably in the range of 40 to 100 N / mm ² . The flexural strength is preferably 10-17 N / mm ^{2 .} The surface hardness of MOC is preferably 50-250

- 9 047521

N/mm ² . The modulus of elasticity is preferably 1-3-10 ⁴ N/mm ² . The bending strength of MOS is relatively low, but it can be significantly improved by adding fibers, in particular cellulose-based fibers. MOS is compatible with a wide range of plastic fibers, mineral fibers (such as basalt fibers) and organic fibers such as bagasse, wood fibers and hemp. The MOS used in the panel according to the invention can be enriched with one or more of these types of fibers. MOS does not shrink, is resistant to abrasion and acceptable wear, impact, dents and scratches. MOS is resistant to heating and freeze-thaw cycles and does not require air entrainment to improve durability. In addition, MOS has excellent thermal conductivity, low electrical conductivity and excellent adhesion to various substrates and additives, and also has acceptable fire retardant properties. MOC is less desirable if the panel is exposed to relatively extreme weather conditions (temperature and humidity), which affect both the setting properties and the formation of the magnesium oxychloride phase. Over time, atmospheric carbon dioxide will react with the magnesium oxychloride to form a surface layer of _Mg2 (OH) _ClCO3-3H2O . This layer serves to slow down the leaching process. Eventually _, additional leaching results in the formation of hydromagnesite _4MgO - _3CO3-4H2O , which is insoluble and allows the cement to maintain its structural integrity.

Magnesium based composition and in particular magnesia cement may be based on magnesium sulphate, in particular the heptahydrate of the sulphate mineral epsomite (MgSO ₄ -7H ₂ O). This latter salt is also known as Epsom salt. In aqueous solution, MgO reacts with MgSO4 to form magnesium oxysulphate cement (MOS), which has very good cementitious properties. In MOS, the most common chemical phase is 5Mg(OH) ₂ -MgSO ₄ -8H ₂ O. Although MOS is not as strong as MOS, MOS is better suited for fire resistant applications because MOS begins to decompose at temperatures more than twice that of MOS, providing longer fire protection. In addition, its decomposition products at elevated temperatures are less harmful (sulphur dioxide) than the oxychloride products (hydrochloric acid), and are also less aggressive. In addition, the weather conditions (humidity, temperature and wind) during application are not as critical for MOS as for MOS. The mechanical strength of MOS cement depends mainly on the type and relative content of crystalline phases in the cement. Four major magnesium salts that can contribute to the mechanical strength of MOS cement were found to exist in the MgO-MgSO ₄ -H ₂ O ternary system at different temperatures from 30 to 120 degrees Celsius 5Mg(OH) ₂ -MgSO ₄ -3H ₂ O (phase 513), 3Mg(OH) ₂ MgSO ₄ 8H ₂ O (phase 318), Mg(OH) ₂ -2MgSO ₄ -3H ₂ O (phase 123), and Mg(OH) ₂ -MgSO ₄ -5H ₂ O (phase 115). Typically, phase 513 and phase 318 could only be obtained by curing the cement under saturated steam conditions, where the molar ratio of MgO to MgSO4 was fixed at (approximately) 5:1. It was found that phase 318 makes a significant contribution to the mechanical strength and is stable at room temperature, and is therefore preferred in the applied MOS. This also applies to phase 513. Said phase 513 typically has a (micro)structure including an _acicular structure. This can be verified by SEM analysis. The needles of magnesium oxysulphate (5Mg(OH) ₂ - _MgSO4-3H2O ) can be virtually uniform and typically have a length of 10-15 µm and a diameter of 0.4-1.0 µm. When referring to an acicular structure, a scaly structure and/or a filiform structure may also be implied. In practice, it is not possible to obtain MOS containing more than 50% of the 513 or 318 phase, but by adjusting the composition of the crystalline phase, the mechanical strength of the MOS can be increased. Preferably, the magnesia cement contains at least 10%, preferably at least 20% and more preferably at least 30% of 5Mg(OH) ₂ - _MgSO4-3H2O (phase 513). This preferred embodiment provides a magnesia cement having sufficient mechanical strength _for use in the core layer of a floor panel.

The crystalline phase of MOS can be controlled by modifying MOS using an organic acid, preferably citric acid and/or phosphoric acid and/or phosphates. During this modification _{, new phases of MOS can be obtained, which can be expressed as 5Mg(OH)2.MgSO4.5H2O ( phase 515} ) and Mg(OH) ₂ - _MgSO4-7H2O (phase 517). Phase 515 can be obtained by modifying MOS using citric acid. Phase 517 can be obtained by modifying MOS using phosphoric acid and/ _{or phosphates} ( _H3PO4 , _{KH2PO4 , K3PO4 and K2HPO4} ). These 515 phase and 517 phase can be determined by chemical elemental analysis, and SEM analysis proves that the microstructure of both the 515 phase and the 517 phase is an acicular crystal, insoluble in water. In particular, the compressive strength and water resistance of MOS can be improved by adding citric acid. Therefore, it is preferable that MOS, if used in the panel according to the invention, contains 5Mg(OH) ₂ -MgSO ₄ -5H ₂ O (phase 515) and/or Mg(OH) ₂ -MgSO ₄ -7H ₂ O (phase 517). As mentioned above, the addition of phosphoric acid and phosphates can increase the setting time and improve the compressive strength and water resistance of MOS cement by changing the hydration process of MgO and the phase composition. In this case, phosphoric acid or phosphates are ionized in solution to form H ₂ PO ₄ ^- , HPO4 ^2- , and/or PO4 ^3- , where these anions are adsorbed onto

- 10 047521

[Mg(OH)( _H2O ) ^x ] ⁺ , inhibiting the formation of Mg(OH) ₂ and further promoting the formation of new magnesium subsulphate phase, resulting in compact structure, high mechanical strength and good water resistance of MOS cement. The improvement brought about by the addition of phosphoric acid or phosphates to MOS cement follows the order _H3PO4 = KH2PO+ >> _K2HPO4 >> _K3PO4 . MOS has better volumetric stability, less shrinkage, better binding properties and less corrosion activity under a much wider range _of weather conditions than MOS and can therefore be preferred over MOS. The density of MOS typically ranges from 350 to 650 kg/ ^m3 . The flexural strength is preferably 1-7 N/ ^mm2 .

The magnesium cement composition preferably comprises one or more silicone-based additives. Various silicone-based additives can be used, including, but not limited to, silicone oils, neutral-curing silicones, silanols, silanol liquids, silicone (micro)spheres or silicone particles, as well as mixtures and derivatives thereof. Silicone oils include liquid polymerized siloxanes with organic side chains, including, but not limited to, poly(methyl)siloxane and its derivatives. Neutral-curing silicones include silicones that release alcohol or other volatile organic compounds (VOCs) upon curing. Other silicone-based additives and/or siloxanes (e.g., siloxane polymers) may also be used, including, but not limited to, hydroxyl-terminated (or hydroxy)-terminated siloxanes and/or siloxanes with other reactive groups, acrylic siloxanes, urethane siloxanes, epoxy siloxanes, and mixtures and derivatives thereof. As described in detail below, one or more crosslinking agents (e.g., silicone-based crosslinking agents) may also be used. The viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) may be about 100 cSt (at 25°C), which is referred to as low viscosity. In alternative embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 20 cSt (25°C) to about 2000 cSt (25°C). In other embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 100 cSt (25°C) to about 1250 cSt (25°C). In other embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 250 cSt (25°C) to 1000 cSt (25°C). In other embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 400 cSt (25°C) to 800 cSt (25°C). And in specific embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 800 cSt (25°C) to about 1250 cSt (25°C). One or more silicone-based additives having a higher and/or lower viscosity can also be used. For example, in further embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 20 cSt (25°C) to about 200,000 (25°C) cSt, from about 1,000 cSt (25°C) to about 100,000 cSt (25°C), or from about 80,000 cSt (25°C) to about 150,000 cSt (25°C). In other embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 1000 cSt (25°C) to about 20,000 cSt (25°C), from about 1000 cSt (25°C) to about 10,000 cSt (25°C), from about 1000 cSt (25°C) to about 2000 cSt (25°C), or from about 10,000 cSt (25°C) to about 20,000 cSt (25°C). In yet other embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 1000 cSt (25°C) to about 80,000 (25°C) cSt, from about 50,000 cSt (25°C) to about 100,000 cSt (25°C), or from about 80,000 cSt (25°C) to about 200,000 cSt (25°C). And in still further embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is from about 20 cSt (25°C) to about 100 cSt (25°C). Other viscosities can also be used if desired.

In a preferred embodiment, the magnesium cement composition, in particular the magnesium oxychloride cement composition, comprises one type of silicone-based additive. In other embodiments, a mixture of two or more types of silicone-based additives is used. For example, in some embodiments, the magnesium oxychloride cement composition may comprise a mixture of one or more silicone oils and neutral-curing silicones. In particular embodiments, the ratio of silicone oil to neutral-curing silicone may be from about 1:5 to about 5:1 by weight. In other embodiments, the ratio of silicone oil to neutral-curing silicone may be from about 1:4 to

- 11 047521 about 4:1 by weight. In other embodiments, the ratio of silicone oil to neutral cure silicone may be from about 1:3 to about 3:1 by weight. In still other embodiments, the ratio of silicone oil to neutral cure silicone may be from about 1:2 to about 2:1 by weight. In further embodiments, the ratio of silicone oil to neutral cure silicone may be about 1:1 by weight.

It can be assumed that one or more crosslinking agents are used in the magnesia cement. In some embodiments, the crosslinking agents are silicone-based crosslinking agents. Examples of crosslinking agents include, but are not limited to, methyltrimethoxysilane, methyltriethoxysilane, methyltris(methylethylketoximino)silane, and mixtures and derivatives thereof. Other crosslinking agents (including other silicone-based crosslinking agents) may also be used. In some embodiments, the magnesium oxychloride cement composition comprises one or more silicone-based additives (e.g., one or more silanols and/or silanol fluids) and one or more crosslinking agents. The ratio of one or more silicone-based additives (e.g., silanols and/or silanol fluids) to the crosslinking agent can be from about 1:20 to about 20:1 by weight, from about 1:10 to about 10:1 by weight, or from about 1:1 to about 10:1 by weight.

Magnesium (oxychloride)-based cement compositions containing one or more silicone-based additives may exhibit reduced sensitivity to water compared to traditional magnesium (oxychloride)-based cement compositions. In addition, in some embodiments, magnesium (oxychloride)-based cement compositions containing one or more silicone-based additives may exhibit little or no sensitivity to water. Magnesium (oxychloride)-based cement compositions containing one or more silicone-based additives may further exhibit hydrophobic and water-resistant properties.

In addition, magnesium (oxychloride)-based cementitious compositions containing one or more silicone-based additives can exhibit improved curing characteristics. For example, magnesium (oxychloride)-based cementitious compositions cure to form _a variety of reaction products, including 3Mg(OH _{) 2} - _MgCl2-8H2O ( _phase 3) and 5Mg(OH) ₂ - _MgCl2-8H2O (phase 5) crystalline structures. In some situations, higher percentages of the 5Mg(OH) ₂ - _MgCl2-8H2O (phase 5) crystalline structure are preferred. In such situations, the addition of one or more silicone-based additives to magnesium oxychloride-based cementitious compositions can stabilize the curing process _, which can increase the percentage yield of 5Mg(OH) ₂ - _MgCl2-8H2O (phase 5) crystalline structures. For example, in some embodiments, magnesium oxychloride compositions including one or more silicone-based additives can cure to form greater than 80% 5Mg(OH) ₂ - _MgCl2-8H2O (phase 5) crystalline structures. In other embodiments, magnesium oxychloride compositions including one or more silicone-based additives can cure to form greater than 85% 5Mg(OH) _{2 - MgCl2-8H2O} (phase ₅ ) crystalline structures. In yet other embodiments, magnesium oxychloride compositions including one or more silicone-based additives can cure to form greater than 90% 5Mg(OH) _{2 - MgCl2-8H2O} (phase 5) crystalline structures. In yet other embodiments, magnesium oxychloride compositions including one or more silicone-based additives can cure to form greater than 95% 5Mg(OH) ₂ - _MgCl2-8H2O (phase 5) crystalline structures. In yet other embodiments, magnesium oxychloride compositions including one or more silicone-based additives can cure to form greater than 98% 5Mg(OH) _{2 -MgCl2-8H2O (} phase 5) crystalline structures. In yet other _embodiments , magnesium oxychloride compositions including one or more silicone-based additives can cure to form about 100% 5Mg(OH) _{2 - MgCl2.8H2O} (phase 5) crystalline structures.

In addition, magnesium (oxychloride)-based cement compositions containing one or more silicone-based additives can also exhibit improved strength and adhesion properties. If desired, magnesium (oxychloride)-based cement compositions containing one or more silicone-based additives can also be used to produce magnesium (oxychloride)-based cement or concrete structures that are relatively thin. For example, magnesium (oxychloride)-based cement compositions containing one or more silicone-based additives can be used to produce cement or concrete structures or layers having a thickness of less than 8 mm, preferably less than 6 mm.

In order to effect a connection between the connecting part, it may be desirable and/or even necessary to temporarily deform the connecting part(s), as a result of which it is advantageous to mix magnesium oxide and/or magnesium hydroxide and/or magnesium chloride and/or magnesium sulfate with one or more silicone-based additives, since this leads to an increased degree of flexibility and/or elasticity. For example, in some embodiments, cement and concrete structures formed using magnesium oxychloride-based cementitious compositions can bend

- 12 047521 or bend without cracking or breaking.

Magnesium (oxychloride)-based cement compositions comprising one or more silicone-based additives may further comprise one or more additional additives. Additional additives may be used to improve specific characteristics of the composition. For example, in some embodiments, additional additives may be used to impart a stone-like (e.g., granite, marble, sandstone, etc.) appearance to structures formed using the disclosed magnesium oxychloride-based cement compositions. In particular embodiments, additional additives may include one or more pigments or colorants. In other embodiments, additional additives may include fibers, including, but not limited to, paper fibers, wood fibers, polymer fibers, organic fibers, and glass fibers. Magnesium oxychloride-based cement compositions may also form UV-resistant structures such that the color and/or appearance are not subject to significant fading when exposed to UV radiation over time. Other additives may also be included in the composition, including, but not limited to, plasticizers (e.g., polycarboxylic acid plasticizers, polycarboxylate ether plasticizers, etc.), surfactants, water, and mixtures and combinations thereof. As noted above, the magnesium oxychloride-based cementitious composition, if used, may comprise magnesium oxide (MgO), an aqueous solution of magnesium chloride (MgCl ₂ (aq)) and one or more silicone-based additives. Magnesium chloride powder (MgCl ₂ ) may also be used instead of an aqueous solution of magnesium chloride (MgCl ₂ ). For example, magnesium chloride powder (MgCl ₂ ) may be used in combination with an amount of water that would be equivalent or otherwise similar to the addition of aqueous magnesium chloride (MgCl2 (aq)).

In some embodiments, the ratio of magnesium oxide (MgO) to hydrous magnesium chloride (MgCl2 (aq)) if used in the magnesium oxychloride cement composition may vary. In some such embodiments, the ratio of magnesium oxide (MgO) to hydrous magnesium chloride ( _MgCl2 (aq)) is from about 0.3:1 to about 1.2:1 by weight. In other embodiments, the ratio of magnesium oxide (MgO) to hydrous magnesium chloride ( _MgCl2 (aq)) is from about 0.4:1 to about 1.2:1 by weight. In still other embodiments, the ratio of magnesium oxide (MgO) to hydrous magnesium chloride ( _MgCl2 (aq)) is from about 0.5:1 to about 1.2:1 by weight.

Aqueous magnesium chloride ( _MgCl2 (aq)) may be described as (or derived from) magnesium chloride brine. Aqueous magnesium chloride ( _MgCl2 (aq)) (or magnesium chloride brine) may also include relatively small amounts of other compounds or substances, including, but not limited to, magnesium sulfate, magnesium phosphate, hydrochloric acid, phosphoric acid, etc.

In a preferred embodiment, the amount of one or more (liquid) silicone-based additives in the magnesium oxychloride-based cementitious composition may be determined as a ratio of silicone-based additives to magnesium oxide (MgO). For example, in some embodiments, the weight ratio of silicone-based additives to magnesium oxide (MgO) is from 0.06 to 0.6.

It is also advantageous and even convenient to include at least one oil in the core layer, such as linseed oil or silicone oil. This gives the magnesium-based core layer and/or the thermoplastic-based middle layer greater flexibility and reduces the risk of breakage. Instead of or in addition to the oil, it is also possible to include one or more water-soluble polymers or polycondensed (synthetic) resins, such as polycarboxylic acid, in the core layer. This leads to the advantage that the panel does not shrink during drying/curing/setting, which prevents cracks from forming, and in addition gives the core layer a more hydrophobic character after drying/curing/setting, which prevents water (moisture) from penetrating during subsequent storage and use.

It can be assumed that the core layer contains polycaprolactone (PCL).

This biodegradable polymer is particularly preferred because it has been found to melt as a result of the exothermic reaction of the reaction mixture. It has a melting point of about 60°C. PCL can be of low density or high density. The latter is particularly preferred because it provides a stronger core layer. Instead of or in addition to other polymers, other polymers can be used, preferably a polymer selected from the group consisting of: other poly(lactic-glycolic acid) (PLGA), poly(lactic acid) (PLA), poly(glycolic acid) (PGA), the polyhydroxyalkanoate family (PHA), polyethylene glycol (PEG), polypropylene glycol (PPG), polyesteramide (PEA), poly(lactic acid-co-caprolactone), poly(lactide-co-trimethylene carbonate), poly(sebacic acid-corticoic acid) and a combination thereof.

Alternatively, the panel, in particular the core layer, may be at least partially made of PVC, PET, PP, PS or (thermoplastic) polyurethane (PUR). The PS may be in the form of expanded PS (EPS) to further reduce the density of the panel, which results in cost savings and facilitates handling of the panels. Preferably, at least part of the used

- 13 047521 polymers can be formed by a recycled thermoplastic, such as recycled PVC or recycled PUR. Recycled PUR can be made on the basis of recycled polymers, for example on the basis of recycled PET. PET can be processed chemically using glycolysis or depolymerization of PET into monomers or oligomers, and then into polyurethane polyols. It can also be assumed that rubber and/or elastomer parts (particles) are dispersed within at least one composite layer to improve flexibility and/or impact resistance to at least some extent. It is quite possible that a mixture of virgin and recycled thermoplastic materials is used to make at least part of the core. Preferably, in this mixture, the virgin thermoplastic material and the recycled thermoplastic material are substantially the same. For example, such a mixture can be entirely PVC-based or entirely PUR-based. The core may be solid or foamed, or both if the core is made up of multiple parts/layers. The core may also contain fillers such as mineral fillers.

It may be advantageous for the core layer to comprise porous granules, in particular porous ceramic granules. Preferably, the granules have a plurality of micropores with an average diameter of from 1 micron to 10 microns, preferably from 4 to 5 microns. That is to say, the individual granules preferably have micropores. Preferably, the micropores are interconnected. Preferably, they are not limited to the surface of the granules, but are located substantially over the entire cross-section of the granules. Preferably, the granule size is from 200 microns to 900 microns, preferably from 250 microns to 850 microns, especially from 250 to 500 microns or from 500 to 850 microns. Preferably, at least two different granule sizes are used, most preferably two. Preferably, small and/or large granules are used. The small granules may have a size of from 250 to 500 microns. Preferably, the large granules have a diameter of from 500 microns to 850 microns. Each granule may have substantially the same size or two or more predetermined sizes. Alternatively, two or more different size ranges may be used with a plurality of particles of different sizes within each range. Preferably, two different sizes or size ranges are used. Preferably, each granule comprises a plurality of microparticles, substantially each microparticle being partially fused with one or more adjacent microparticles to form a lattice defining micropores. Each microparticle preferably has an average size of 1 micron to 10 microns, with an average of 4 to 5 microns. Preferably, the average size of the micropores is 2 to 8 microns, most preferably 4 to 6 microns. The micropores may have an irregular shape. Accordingly, the size of the micropores and even the average pore size mentioned below is determined by adding the widest pore diameter to the narrowest pore diameter and dividing by 2. Preferably, the ceramic material is uniformly distributed over the cross-section of the core layer, i.e. substantially without forming lumps of the ceramic material. Preferably, the microparticles have an average size of at least 2 microns or 4 microns and/or less than 10 microns or less than 6 microns, most preferably from 5 to 6 microns. This range of particle sizes has been found to provide controlled formation of micropores.

The granules may also comprise a plurality of substantially spherical medium-sized pores having an average diameter of 10 to 100 microns. They substantially increase the overall porosity of the ceramic material without compromising the mechanical strength of the materials. The medium-sized pores are preferably interconnected via a plurality of micropores. That is, the medium-sized pores may be in hydraulic communication with each other via the micropores. The average porosity of the ceramic material itself is preferably at least 50%, more preferably more than 60%, most preferably 70 to 75% of the average porosity. The ceramic material used to make the granules may be any (non-toxic) ceramic known in the art, such as calcium phosphate and glass ceramics. The ceramic may be silicate, although it is preferably calcium phosphate, especially [alpha]- or [beta]tricalcium phosphate or hydroxyapatite, or mixtures thereof. Most preferably, the mixture is hydroxyapatite and [beta]-tricalcium phosphate, especially more than 50% by weight of [beta]-tricalcium, most preferably 85% of [beta]-tricalcium phosphate and 15% of hydroxyapatite. Most preferably, the material is 100% hydroxyapatite. Preferably, the cement composition or dry premix comprises from 15 to 30% by weight of granules based on the total dry weight of the composition or premix.

Porous particles can result in a lower average density of the core layer and thus in a reduction in mass, which is advantageous from an economic and handling point of view. Furthermore, the presence of porous particles in the core layer usually results, at least to some extent, in an increased porosity of the porous upper surface and the lower surface of the core layer, which is advantageous for the attachment of an additional layer to the upper surface and/or the lower surface of the core layer, such as, for example, a primer layer, an (initially liquid) adhesive layer or another decorative or functional layer. Often these layers are initially applied in a liquid state, whereby the pores allow the liquid substance to be sucked (penetrated) into the pores, which increases the contact surface area between the layers and thus

- 14 047521 improves the adhesion strength between the specified layers.

The panels may have a multilayer structure comprising, for example, a central core (or core layer) and at least one decorative upper section, directly or indirectly attached to said core layer or combined with said core layer, wherein the upper section forms the upper surface of the panel. The upper section preferably comprises at least one decorative layer attached directly or indirectly to the upper surface of the core layer. The decorative layer may be a printed layer and/or may be covered with at least one protective (top) layer covering said decorative layer. The protective layer is also part of the decorative upper section. The presence of a printed layer and/or a protective layer may prevent damage to the panel due to scratches and/or environmental factors such as ultraviolet radiation/moisture and/or wear and tear. The printing layer can be formed by a film on which a decorative print is applied, wherein the film is attached to the base layer and/or an intermediate layer, such as a primer layer, located between the base layer and the decorative layer. The printing layer can also be formed by at least one paint layer, which is applied directly to the upper surface of the core layer or to a primer layer applied to the base layer. The panel can comprise at least one wear-resistant layer, attached directly or indirectly to the upper surface of the decorative layer. The wear-resistant layer is also part of the decorative upper section. Each panel can comprise at least one varnish layer, attached directly or indirectly to the upper surface of the decorative layer, preferably to the upper surface of the wear-resistant layer.

The underside (rear side) of the core (core layer(s)) may also constitute the underside (rear side) of the panel as such. However, it is possible and may even be preferable for the panel to comprise a backing layer directly or indirectly attached to said underside of the core. As a rule, the protective layer acts as a balancing layer for stabilizing the shape, in particular the flatness of the panel as such. Moreover, the backing layer usually contributes to the sound-absorbing properties of the panel as such. Since the backing layer usually represents a closed layer, the application of the backing layer to the underside of the core covers the grooves of the core at least partially and preferably completely. In this case, the length of each groove of the core is preferably shorter than the length of said backing layer. The backing layer may be provided with cut-out portions, wherein at least a part of said cut-out portions is overlapped by at least one groove of the core. At least one underlayment layer is preferably at least partially made of a flexible material, preferably an elastomer. The thickness of the underlayment layer typically ranges from about 0.1 to 2.5 mm. Non-limiting examples of materials that the underlayment layer may at least partially consist of are polyethylene, cork, polyurethane, polyvinyl chloride and ethylene vinyl acetate. Optionally, the underlayment layer contains one or more additives, such as fillers (e.g. chalk), dyes, resins and/or one or more plasticizers. In a particular embodiment, the underlayment layer is at least partially made of a composite of ground (or chipped) cork particles bonded with resin. Instead of cork, other wood-related products, such as wood, can be used. The thickness of the polyethylene underlayment layer is typically, for example, 2 mm or less. The underlayment layer can be solid or foamed. A foamed underlayment layer can further improve the sound-absorbing properties. A solid underlayment layer can improve the desired balancing effect and stability of the panel.

The panels may comprise a core comprising a rigid closed-cell foam material. An additional advantage of using the foam material is that the presence of closed cells not only results in increased rigidity and increased impact resistance, but also in a reduced density and lower weight compared to a similarly sized non-foamed plastic material. The rigidity of the base or core layer may be further increased by using a substance increasing impact strength, wherein the base layer of the closed-cell foam material contains, for example, from 3% to 9% by weight of a substance increasing impact strength. Due to the fact that the connecting parts have a specific shape, the substantially complementary resulting connecting parts of adjacent panels can be connected to each other in a relatively simple, but durable and effective manner.

Foamed plastic materials that are suitable for forming the foamed base layer may include foamed plastics made of polyurethane, polyamide copolymers, polystyrene, PVC, polypropylene and polyethylene, all of which have good processing properties when molded. PVC foamed materials are particularly suitable for forming the foamed base layer, since they are chemically stable, corrosion-resistant and have excellent fire-retardant properties. Preferably, CPVC and/or CPE and/or another chlorinated thermoplastic material is/are used to further increase the hardness and rigidity of the base layers and the panels as such. The plastic material used as the foamed plastic material in the base layer,

- 15 047521 does not contain any plasticizer for increasing the desired rigidity of the base layer, which, in addition, is also favorable from the point of view of the environment. The foam plastic material according to the invention also contains foamed plastic composites and foamed composites containing plastic materials. The substantially rigid base layer of each panel is at least partially made of a composite containing a closed-cell foam plastic material and at least one filler. Conventional materials such as HDF and MDF are less durable than the above-mentioned foamed composite and quickly lead to destruction and/or damage. The base layer composite contains one or more fillers, wherein at least one filler is selected from the group consisting of: talc, chalk, wood, calcium carbonate, titanium dioxide, calcined clay, porcelain, (another) mineral filler and (another) natural filler. The filler may be formed by fibers and/or may be formed by dust-like particles. In this case, the term dust is understood to mean small dust-like particles (powder), like wood dust, bark dust or non-wood dust, like mineral dust, stone dust, in particular cement. The average particle size of the dust is preferably in the range of 14 to 20 microns, more preferably from 16 to 18 microns. The mass content of this type of filler in the composite is in the range of 40 to 48%, in the case where the composite is a foamed composite, and preferably from 65 to 70%, in the case where the composite is a non-foamed (solid) composite. The filler of the base layer can be, for example, selected from the group consisting of: salt, stearate salt, calcium stearate and zinc stearate. Stearates act as a stabilizer and result in a more favorable processing temperature and the exclusion of decomposition of the components of the composite during and after processing, thus ensuring long-term stability. Instead of or in addition to stearate, calcium zinc, for example, can also be used as a stabilizer. The weight content of the stabilizer(s) in the composite will preferably be in the range of 1 to 5%, and more preferably 1.5 to 4%.

The base layer or the base layer composite preferably comprises at least one impact modifier comprising at least one alkyl methacrylate, wherein said alkyl methacrylate is preferably selected from the group consisting of: methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, t-butyl methacrylate and isobutyl methacrylate. The impact modifier typically improves the product properties, in particular the impact resistance. Furthermore, the impact modifier typically increases the impact strength of the base layer and can therefore also be considered as an impact enhancing substance that further reduces the risk of failure. Often, the modifier also contributes to the manufacturing process, for example to control the formation of foam with a relatively uniform (constant) foam structure. The weight content of the impact modifier in the composite will preferably be in the range of from 1 to 9%, and more preferably from 3 to 6%.

The base layer may also at least partially consist of a (PVC-free) thermoplastic composition. The thermoplastic composition may comprise a polymer matrix comprising: (a) at least one ionomer and/or at least one acidic copolymer; and (b) at least one styrene thermoplastic polymer and, optionally, at least one filler. The ionomer is understood to be a copolymer that contains repeating fragments of electrically neutral and ionized fragments. The ionized fragments of the ionomers may in particular be carboxylic acid groups that are partially neutralized by metal cations. The ionic groups are usually present in small amounts (usually less than 15 mol.% of the constituent fragments), which causes microphase separation of the ionic domains from the continuous polymer phase and acts as physical crosslinks. The result is an ion-reinforced thermoplastic with improved physical properties compared to conventional plastics.

The density of the foamed base layer typically ranges from about 0.1 to 1.5 grams/ ^cm3 , preferably from about 0.2 to 1.4 grams/ ^cm3 , more preferably from about 0.3 to 1.3 grams/ ^cm3 , even more preferably from about 0.4 to 1.2 grams/ ^cm3 , even more preferably from about 0.5 to 1.2 grams/ ^cm3 and most preferably from about 0.6 to 1.2 grams/ ^cm3 .

The base layer may comprise at least one foaming agent. The at least one foaming agent ensures foaming of the base layer, which will reduce the density of the base layer. This will result in a reduction in the weight of the panels, which have a lower weight compared to panels of similar dimensions and having a non-foamed base layer. The preferred foaming agent depends on the (thermo)plastic material used in the base layer, as well as on the desired foam ratio, the foam structure, and preferably also on the desired (or required) foam temperature for realizing the desired foam ratio and/or foam structure. For this purpose, it may be advantageous to use a plurality of foaming agents, which are configured to foam the base layer at different temperatures, respectively. This will allow the foamed base layer to be realized in a more consistent and more controllable manner. Examples of two different foaming agents that may be present (simultaneously) in the base layer are azodicarbonamide and sodium bicarbonate. In this regard, it is also often advantageous to use

- 16 047521 at least one modifying agent, such as methyl methacrylate (MMA), to keep the foam structure relatively uniform throughout the base layer.

Each panel comprises a top backing attached to the top side of the base layer, said backing comprising a decorative layer.

The upper substrate is preferably at least partially made of at least one material selected from: metals, alloys, macromolecular materials such as copolymers and/or homopolymers of vinyl monomers; condensation polymers such as polyesters, polyamides, polyimides, epoxy resins, phenol-formaldehyde resins, urea-formaldehyde resins, natural macromolecular materials or their modified derivatives such as plant fibers, animal fibers, mineral fibers, ceramic fibers and carbon fibers. In this case, the homopolymers of vinyl monomers are preferably selected from the group consisting of polyethylene, PVC, polystyrene, polymethacrylates, polyacrylates, polyacrylamides, ABS (acrylonitrile butadiene styrene) copolymers, polypropylene, ethylene-propylene copolymers, polyvinylidene chloride, polytetrafluoroethylene, polyvinylidene fluoride, hexafluoropropylene and styrene-maleic anhydride copolymers and derivatives thereof. The upper substrate most preferably comprises polyethylene or PVC. The polyethylene may be low-density polyethylene, medium-density polyethylene, high-density polyethylene or ultra-high-density polyethylene. The upper substrate layer may also include fillers and other additives that improve the physical properties and/or chemical properties and/or technological characteristics of the product. These additives include known substances that increase impact strength, plasticizing substances, reinforcing substances, anti-mold (antiseptic) substances, fire-retardant substances, etc. The upper substrate usually comprises a decorative layer and an abrasion-resistant wear-resistant layer covering said decorative layer, wherein the upper surface of said wear-resistant layer is the upper surface of said panel, and wherein the wear-resistant layer is a transparent material so that the decorative layer is visible through the transparent wear-resistant layer.

The thickness of the upper substrate usually varies from about 0.1 to 2 mm, preferably from about 0.15 to 1.8 mm, more preferably from about 0.2 to 1.5 mm, and most preferably from about 0.3 to 1.5 mm. The ratio of the thickness of the base layer to the thickness of the upper substrate usually varies from about 1 to 15: 0.1 to 2, preferably from about 1.5 to 10: 0.1 to 1.5, more preferably from about 1.5 to 8: 0.2 to 1.5, and most preferably from about 2 to 8: 0.3 to 1.5, respectively.

Each panel may comprise an adhesive layer for attaching the upper substrate, directly or indirectly, to the base layer. The adhesive layer may be any well-known adhesive or binder capable of gluing together the upper substrate and the foamed base layer, such as polyurethanes, epoxy resins, polyacrylates, ethylene vinyl acetate copolymers, ethylene acrylic acid copolymers, etc. Preferably, the adhesive layer is a hot-melt adhesive. The base layer or core and the upper substrate may also be fused.

The decorative layer or design layer, which may be part of the upper substrate as mentioned above, may comprise any suitable known plastic material, such as a known PVC resin composition, a stabilizer, a plasticizer and other additives that are well known in the art. The design layer may be made with or printed with printed patterns, such as wood design, metal design, stone design and fiber patterns or three-dimensional figures. Thus, the design layer can give the panel a three-dimensional appearance that resembles heavier products such as granite, stone or metal. The thickness of the design layer typically ranges from about 0.01 to 0.1 mm, preferably from about 0.015 to 0.08 mm, more preferably from about 0.2 to 0.7 mm, and most preferably from about 0.02 to 0.5 mm. The wear layer, which typically forms the upper surface of the panel, may comprise any suitable known abrasion-resistant material, such as an abrasion-resistant macromolecular material applied to the layer below it, or a known ceramic bead coating. If the wear layer is provided as a layer, it may be bonded to the layer below it. The wear layer may also comprise a layer of organic polymer and/or a layer of inorganic material, such as an ultraviolet coating or a combination of another layer of organic polymer and an ultraviolet coating. For example, an ultraviolet paint is capable of increasing the surface scratch resistance, gloss, resistance to antimicrobial agents and other properties of the product. If necessary, other organic polymers may be included, including polyvinyl chloride resins or other polymers, such as vinyl resins, and a suitable amount of a plasticizer and other processing additives. The decorative layer or design layer may also be printed by digital printing directly onto the core layer.

The foam used in the core layer preferably has a modulus of elasticity greater than 700 MPa (at 23 degrees Celsius and 50% relative humidity). This generally provides sufficient rigidity for the core layer and therefore for the panel itself.

- 17 047521

In one embodiment, the connecting parts are designed to be connected by a movement that is perpendicular to the plane of the panels. The connecting part can, for example, be essentially hook-shaped and made in analogy with the third and fourth connecting parts, as described for this invention. In general, in one embodiment, the wall panels, instead of the first and second connecting parts, can be provided with only the third and fourth. Preferably, the third connecting part comprises an upwardly directed tongue, at least one upwardly directed side surface lying at a distance from the upwardly directed tongue, and an upwardly directed groove formed between the upwardly directed tongue and the upwardly directed side surface, wherein the upwardly directed intermediate part connects the upwardly directed tongue to the core, wherein the upwardly directed groove is configured to accommodate at least a portion of the downwardly directed tongue of the fourth connecting part of the other panel, wherein the side of the upwardly directed tongue facing the upwardly directed side surface is the inner surface of the upwardly directed tongue, and the side of the upwardly directed tongue facing away from the upwardly directed side surface is the outer surface of the upwardly directed tongue; wherein the fourth connecting portion comprises a downwardly directed tongue, at least one downwardly directed lateral surface lying at a distance from the downwardly directed tongue, and an upwardly directed groove formed between the downwardly directed tongue and the downwardly directed lateral surface, wherein the downwardly directed intermediate portion connects the downwardly directed tongue and the core, wherein the downwardly directed groove is configured to accommodate at least a portion of the upwardly directed tongue of the first connecting portion of the other panel, wherein the side of the downwardly directed tongue facing the downwardly directed lateral surface is an inner surface of the downwardly directed tongue, and the side of the downwardly directed tongue facing away from the downwardly directed lateral surface is an outer surface of the downwardly directed tongue. The inner surfaces of the upwardly directed and downwardly directed tongues may be inclined toward the core in such a way that a so-called closed-groove locking can be ensured. A recess may then be provided in the upwardly directed intermediate portion, passing at least partially through this intermediate portion and configured to be accessible from the surface of the upwardly directed intermediate portion. Other features described in other embodiments may also apply to this embodiment.

Preferably, the upper surface of the lower lip forms the lower part of said groove, and in particular the lower surface of said lower part of said groove. Preferably, the distal end of the upper lip forms a joint vertical plane (VP), wherein the lower lip and said lower part of said groove extend beyond said joint vertical plane. This facilitates the production of the connecting profile(s) and, in addition, facilitates the connection of the connecting profiles of adjacent wall panels relative to each other, since the groove is relatively accessible to a sufficient extent, which makes it relatively easy to insert a laterally directed tongue into said groove. Preferably, the lower part of the groove is located on both sides of the joint vertical plane. In addition to the advantages presented above in this paragraph, this further contributes to the implementation of a reliable connection between the connecting profiles, preferably both in the horizontal direction (perpendicular to the joint vertical plane) and in the vertical direction (parallel to the joint vertical plane). The lower part of the groove preferably partially forms the inner surface of the upwardly directed locking element. Said inner surface is usually inclined, wherein said inner surface preferably forms an angle with the joint vertical plane of 30 to 60 degrees, more preferably about 45 degrees.

The lower surface of the lower lip preferably forms the lowermost surface of the groove, said lowermost surface extending up to but not including the upwardly directed locking element. Preferably, said lower surface extends beyond the joint vertical plane. More preferably, the lowermost surface of the groove is located on both sides of the joint vertical plane. The lowermost surface of the groove is preferably substantially flat. Preferably, the lowermost surface of the groove is substantially perpendicular to the joint vertical plane (and therefore substantially horizontal in the case where the panel rests on a horizontal support surface). The lower part of the groove is preferably located on both sides of the joint vertical plane, substantially dividing the lower part into an inner lower part and an outer lower part, wherein the lower part has a width perpendicular to the joint vertical plane, and wherein the width of the outer lower parts exceeds the width of the inner lower part, and more preferably, the width of the outer lower parts is at least twice the width of the inner lower part. As stated above, this improves groove accessibility, which allows for relatively simple and user-friendly insertion of the sideways-facing tongue into the groove.

The sideways tongue preferably has a lowermost surface that is connected

- 18 047521 in the given state of the adjacent wall panels is located on both sides of the common vertical plane. The sideways tongue preferably has a flat lowermost surface. At least a portion of the lowermost surface of the sideways tongue preferably extends substantially perpendicular to the common vertical plane. It can also be assumed that at least a portion of the lowermost surface of the sideways tongue is inclined upward toward the upper intermediate portion, wherein the inclined lowermost surface and the common vertical plane mutually preferably form an angle of 85 to 90 degrees.

Preferably, the lowermost surface of the sideways tongue abuts the lower surface of the groove in the connected state of the adjacent panels. Such a stop usually increases the stability of the connection between said panels. More preferably, the lowermost point (the deepest point) of the lowermost surface of the sideways tongue abuts the lower surface of the groove in the connected state of the adjacent panels. Preferably, a portion of the lowermost surface of the sideways tongue abuts the lower surface of the groove in the connected state of the adjacent panels in such a way that the stop is located below the upper lip. Outside the joint vertical plane, at least a portion of the lowermost surface of the sideways tongue and the lower surface of the groove in the connected state of the adjacent panels are preferably located at a distance from each other. Usually, this facilitates the connection of the connecting profiles of adjacent wall panels, while still ensuring a stable and reliable connection.

The sideways tongue preferably comprises an inner contact surface which borders the downwardly directed groove, wherein said inner contact surface of the sideways directed groove is designed to interact, preferably in displacement, with the inner surface of the upwardly directed fixing element. Preferably, the lower part of the sideways tongue, passing between said inner contact surface and said end part of the sideways tongue, is located at a level coinciding with the level of the upper side of the upwardly directed fixing element or below it. This means that a significant part of the sideways tongue is located at a relatively low level, which ensures the manufacture of the panel in a relatively simplified manner, wherein the thickness of the panel can remain limited. This allows saving material, which reduces costs and facilitates the handling and installation of wall panels.

Preferably, the sideways tongue comprises an end portion which is at least partially substantially parallel to the joint vertical plane. This results in the end portion becoming at least partially substantially vertical. Preferably, at least a part of said end portion of the sideways tongue is located at a level below the level of the upper side of the upwardly directed locking element.

The recess of the upwardly directed fixing element and the grooves are preferably spaced apart. This means that the second connecting profile is provided with a connecting part for the mutual connection of the panels and a separate fastening part for fixing the panel to the supporting structure (wall, ceiling or subfloor).

The invention further relates to a method for installing a wall covering, preferably using wall panels according to any of the preceding claims, comprising the steps of:

a. providing a first wall panel with first and second connecting portions on at least two opposite sides;

b. attaching the first wall panel to the supporting surface, while leaving the second connecting portion of the first wall panel accessible;

c. providing a second wall panel with first and second connecting portions on at least two opposite sides;

d. placing the first connecting portion of the second wall panel in the second connecting portion of the first wall panel;

e. tilting the second wall panel to align with the first panel, while leaving the second connecting portion of the second wall panel accessible;

f. optionally repeating steps c-e with an additional panel.

Before the first wall panel, a starting wall panel with only the second connecting part may be provided; and/or the ending wall panel may be the last wall panel with only the first connecting part. These parts may be used for the peripheral parts of the wall covering, since the sides or the top and bottom depend on the orientation of the panels. On the edges or peripheral parts, the panels are usually not attached to other panels, since there is not enough space for this. Then, only one of the connecting parts is provided so that the covering can be located flush or aligned with the edges of the wall for which the covering is made.

Preferred embodiments of the invention are set forth in the non-limiting set of points presented below:

1. A wall panel for forming a wall covering using a plurality of panels,

- 19 047521 holding:

a. a core comprising a back side, a decorative side opposite the back side, and at least two sides of said core comprising connecting parts for interconnecting several panels;

b. wherein the connecting parts comprise at least one first connecting part and at least one second connecting part located on opposite sides of the core, wherein at least one first connecting part and at least one second connecting part are designed with the possibility of connecting by an inclined movement,

c. wherein the first connecting portion comprises a laterally directed tongue, an upper intermediate portion for connecting the laterally directed tongue to the core and a downwardly directed groove for receiving at least a portion of the upwardly directed locking element, and

d. wherein the second connecting part comprises a groove for receiving at least a portion of a laterally directed tongue, formed by an upper lip and a lower lip extending from the core, wherein the end portion of the lower lip is provided with an upwardly directed locking element, wherein the laterally directed tongue has an inner surface facing the lower lip, an outer surface facing away from the upper lip, and an upper side between the inner surface and the outer surface;

e. wherein said upper side of the upwardly directed fixing element is provided with a recess extending at least partially through the upwardly directed fixing element for receiving at least one fastening element, such as a screw, for fixing the wall panel to the wall.

2. A wall panel according to any of the preceding claims, characterized in that the inner surface of the upwardly directed fixing element comprises first fixing surfaces, and the side of the sideways directed tongue facing the core comprises a second fixing surface, and the fixing surfaces interact to ensure fixation of the panels in a connected state.

3. A wall panel according to any of the preceding claims, characterized in that the side of the sideways tongue facing the decorative side comprises a third fixing surface, and the side of the upper lip facing away from the decorative side comprises a fourth fixing surface, and the fixing surfaces interact to ensure fixation of the panels in a connected state.

4. A wall panel according to any of the preceding claims, characterized in that the recess is provided with beveled edges, and preferably the recess in cross-section has essentially the shape of a truncated cone, widest on the decorative side, tapering towards the back side.

5. A wall panel according to any of the preceding claims, characterized in that the recess is located in the center of the upwardly directed fixing element, in particular between the inner surface and the outer surface of the upwardly directed fixing element.

6. A wall panel according to any of the preceding paragraphs, characterized in that the recess extends at most to half of the upwardly directed fixing element.

7. A wall panel according to any of the preceding claims, characterized in that the part of the side of the sideways tongue facing away from the upper intermediate part and/or at least part of the groove between the upper and lower lip is partially rounded.

8. A wall panel according to any of the preceding claims, characterized in that in the connected state there is an intermediate space between the side of the sideways directed tongue facing the back side and the lower lip, and the intermediate space narrows inward from the upwardly directed locking element.

9. A wall panel according to any of the preceding claims, characterized in that the width of the upwardly directed fixing element is smaller compared to the width of the upper intermediate part so that, preferably in the connected state, there is an intermediate space between the outer surface of the upwardly directed fixing element and the core of the other panel.

10. A wall panel according to any one of the preceding claims, characterized in that the first connecting part comprises a first upper contact surface between the decorative side and the sideways tongue, and wherein the side of the upper lip facing away from the core comprises a second upper contact surface, wherein the first and second upper contact surfaces are arranged so as to be in contact at least partially when connected.

11. A wall panel according to claim 10, characterized in that the first and/or second contact surfaces comprise an upper fixing element, wherein preferably both contact surfaces comprise upper fixing elements that are designed to interact in a connected state to ensure fixation in one or more directions.

- 20 047521

12. A wall panel according to any of the preceding claims, characterized in that the first and/or second connecting parts comprise a bevel or grout located on the decorative side of the panel.

13. A wall panel according to any of the preceding claims, characterized in that the core comprises a thermoplastic material, in particular a foamed or non-foamed thermoplastic material or PVC, polypropylene, polyethylene or polyurethane and/or one or more fillers such as calcium carbonate or a wood material, for example MDF, HDF or wood-plastic material.

14. A wall panel according to any one of the preceding claims, characterized in that the sideways tongue and groove are designed to apply a clamping force in the connected state to compress two connected panels together.

15. A wall panel according to any of the preceding claims, characterized in that the groove comprises a channel extending from the groove to the back of the wall panel.

16. A wall panel according to any of the preceding claims, characterized in that the panel is elongated and is designed to be horizontally positioned to form part of a wall covering, wherein preferably the first and second connecting parts are located on the long sides of the panel and/or wherein two other opposite sides of the wall panel are provided with a third and fourth connecting parts, preferably designed to be connected by the same tilting movement as the first and second connecting parts.

17. A wall panel according to any of the preceding claims, characterized in that the panel is elongated and is designed to be vertically positioned to form part of a wall covering, wherein preferably the first and second connecting parts are located on the long side of the panel and/or wherein two other opposite sides of the wall panel are provided with connecting parts.

18. A wall panel according to any of the preceding claims, characterized in that the panel is elongated, wherein the first and second connecting parts are located on the long side of the panel and wherein along the long side there is a plurality of recesses, preferably evenly distributed along the long side.

19. A wall panel according to any one of the preceding claims, characterized in that the recess in the upwardly directed fixing element forms a recessed groove running along one side of the wall panel, preferably the long side of the elongated panel.

20. A wall panel according to any one of the preceding claims, characterized in that the lower lip extends beyond the upper lip along a distance that is at least 2 times, preferably at least 3 times, more preferably about 4 times the thickness of the wall panel.

21. A wall panel according to any of the preceding claims, characterized in that the thickness of the upwardly directed fixing element is approximately half the thickness of the wall panel.

22. A wall panel according to any of the preceding claims, characterized in that in the connected state of two panels there is an intermediate space between the upper intermediate part of the first panel and the upwardly directed fixing element of the second panel, at least over the entire width of the upwardly directed fixing element, and the intermediate space continues between the distal end of the upwardly directed fixing element of the second panel and the core of the first panel.

23. A wall panel according to any one of the preceding claims, characterized in that the upwardly directed fixing element on the back side opposite the surface side comprises an adhesive layer, such as a thin layer of glue, for temporarily attaching the wall panel to the supporting surface.

24. A wall panel according to any of the preceding claims, characterized in that the upper surface of the lower lip forms the lower part of said groove, wherein the distal end of the upper lip forms a joint VP, and wherein the lower lip and said lower part of said groove extend beyond said joint vertical plane.

25. A wall panel according to any of the preceding claims, characterized in that the lower part of the groove is located on both sides of the common vertical plane.

26. A wall panel according to any of the preceding claims, characterized in that the lower part of the groove is partially formed by the inner surface of the upwardly directed fixing element.

27. A wall panel according to any of the preceding claims, characterized in that the upper surface of the lower lip forms the lowermost surface of the groove, said lowermost surface extending up to but not including the upwardly directed locking element, and said lower surface extending beyond the joint vertical plane.

28. A wall panel according to item 27, characterized in that the lowest surface of the groove is located on both sides of the joint vertical plane.

29. A wall panel according to item 27 or 28, characterized in that the lowest surface of the groove is

- 21 047521 is essentially flat.

30. A wall panel according to one of paragraphs 27-29, characterized in that the lowest surface of the groove is substantially perpendicular to the joint vertical plane.

31. A wall panel according to any of the preceding claims, characterized in that the lower part of the groove is located on both sides of the joint vertical plane, substantially dividing the lower part into an inner lower part and an outer lower part, wherein the lower part has a width perpendicular to the joint vertical plane, and wherein the width of the outer lower parts exceeds the width of the inner lower part.

32. A wall panel according to item 31, characterized in that the width of the outer lower parts is at least twice the width of the inner lower part.

33. A wall panel according to any of the preceding paragraphs, characterized in that the sideways tongue has a lowermost surface which, in the connected state of adjacent wall panels, is located on both sides of the common vertical plane.

34. A wall panel according to any of the preceding claims, characterized in that the sideways tongue has a substantially flat lowermost surface.

35. A wall panel according to any of the preceding claims, characterized in that the sideways tongue has a lowermost surface that extends substantially perpendicular to the joint vertical plane.

36. A wall panel according to any of the preceding claims, characterized in that the sideways tongue has an upwardly inclined lowermost surface toward the upper intermediate portion, wherein the inclined lowermost surface and the combined vertical plane together form an angle of from 85 to 90 degrees.

37. A wall panel according to any of the preceding claims, characterized in that the laterally directed tongue comprises an internal contact surface that borders a downwardly directed groove, wherein said internal contact surface of the laterally directed groove is configured to interact with the internal surface of the upwardly directed locking element.

38. A wall panel according to claim 37, characterized in that the lower part of the sideways tongue, passing between said internal contact surface and said end part of the sideways tongue, is located at a level coinciding with the level of the upper side of the upwardly directed fixing element or below it.

39. A wall panel according to any of the preceding claims, characterized in that the sideways tongue comprises an end portion that is substantially parallel to the joint vertical plane.

40. A wall panel according to any of the preceding claims, characterized in that at least part of said end portion of the sideways tongue is located at a level below the level of the upper side of the upwardly directed fixing element.

41. A wall panel according to any of the preceding claims, characterized in that the recess of the upwardly directed fixing element and the groove are located at a distance from each other.

42. A method for installing a wall covering, preferably using wall panels according to any of the preceding claims, comprising the steps of:

a. providing a first wall panel with first and second connecting portions on at least two opposite sides;

b. attaching the first wall panel to the supporting surface, while leaving the second connecting portion of the first wall panel accessible;

c. providing a second wall panel with first and second connecting portions on at least two opposite sides;

d. placing the first connecting portion of the second wall panel in the second connecting portion of the first wall panel;

e. tilting the second wall panel to align with the first panel, while leaving the second connecting portion of the second wall panel accessible;

f. optionally repeating steps c-e with an additional panel.

43. The method according to claim 42, characterized in that before providing the first wall panel, an initial wall panel with only the second connecting part is provided; and/or characterized in that the final wall panel is the last wall panel with only the first connecting part.

The invention will now be explained on the basis of non-limiting examples of embodiments, which are illustrated in the following figures. The corresponding elements are designated in the figures by corresponding reference numbers. In the figures:

Fig. 1 is a schematic view showing a detailed view of two wall panels in a connected state to form a wall covering according to the present invention.

Fig. 2 shows a detailed view of Fig. 1 with a fastening element;

- 22 047521 Fig. 3 schematically shows a wall covering with three panels according to the present invention;

Fig. 4 shows schematically the wall covering shown in Fig. 3 in an inverted configuration;

Fig. 5 schematically shows a variation of Fig. 4;

Fig. 6 is a schematic side view of three wall panels forming a wall covering according to the present invention;

Fig. 7 schematically shows variations of the coating shown in Fig. 6;

Fig. 8 shows schematically an example of the connecting parts on the other sides of the panel; and Fig. 9 shows schematically a variation of Fig. 2.

Fig. 1 schematically shows a detailed view of two wall panels (1) in a connected state to form a wall covering. Each panel (1) comprises a centrally located core (2), wherein the core comprises a back side (2a), a decorative side (2b) opposite the back side (2a), and at least two sides (3, 4) comprising connecting parts for interconnecting several panels. Fig. 1 shows two sides (3, 4) in a connected state, in which the sides interact.

The connecting parts comprise at least one first connecting part (5) and at least one second connecting part (6) located on opposite sides of the core (2), wherein the first connecting part (5) comprises a laterally directed tongue (7) and an upper connecting part (8) for connecting the laterally directed tongue (7) to the core (2), as well as a downwardly directed groove (9). The second connecting part (6) comprises a groove (10) formed by an upper lip (11) and a lower lip (12) extending from the core (2), wherein the lower lip (12) is provided with an upwardly directed fixing element (13) located at a distance from the core (2), wherein the upwardly directed fixing element (13) has an inner surface (13a) facing the core (2), an outer surface (13b) facing away from the core (2), and a side (13c) of the surface between the inner surface (13a) and the outer surface (13b).

The upwardly directed fixing element (13) is provided with a recess (14) passing partially through the upwardly directed fixing element (13), wherein the recess (14) is accessible from the side of the surface (13c) of the upwardly directed fixing element (13) and passes to the opposite side (13d) of the upwardly directed fixing element (13). The recess (14) is provided for a given location for attaching the wall panel (1) to a supporting surface, such as a beam. For example, a nail, a screw or a staple can be used for attaching the wall panel (1), wherein the head of the nail or the head of the screw, for example, is countersunk into the recessed space of the recess (14).

The inner surface (13a) of the upwardly directed fixing element (13) comprises a first fixing surface (18), and the side of the sideways directed tongue (7) facing the core (2) comprises a second fixing surface (19), wherein the fixing surfaces interact to ensure fixation of the panels in the connected state. The side of the sideways directed tongue (7) facing the decorative side (2b) comprises a third fixing surface (20), and the side of the upper lip (11) facing away from the decorative side comprises a fourth fixing surface (21), wherein the fixing surfaces interact to ensure fixation of the panels in the connected state.

The recess (14) is provided with beveled edges (22) with essentially the shape of a truncated cone in cross-section, widest on the decorative side, tapering towards the back side. The recess (14) is located centrally in the upwardly directed fixing element (13) between the inner surface (13a) and the outer surface (13b) of the upwardly directed fixing element (13).

Fig. 2 shows a detailed view of Fig. 1, wherein the screw (15) is shown with its head (16) located at least partially in the recess (14). Fig. 2 also shows that in the connected state there is an intermediate space (23) between the side of the sideways tongue (7) facing the back (2a), or the lower part of the sideways tongue (7) and the lower lip (12), wherein the intermediate space narrows from the upwardly directed locking element (13) to the core (2). As shown, the width of the upwardly directed locking element (13) is smaller compared to the width of the upper intermediate part (8) such that there is a space (24) between the outer surface (13b) of the upwardly directed locking element (13) and the core (2) of the other panel in the connected state in the shown configuration of the panel on the right.

The first connecting part comprises a first upper contact surface (25) between the decorative side (2b) and the sideways tongue (7), and the side of the upper lip (11) facing away from the core (2) comprises a second upper contact surface (26), wherein the first and second upper contact surfaces face each other and are preferably in contact at least partially.

The various characteristics of the implementation variant are visualized by means of dashed lines.

- 23 047521 shown in Fig. 2. For this purpose, the upper lip (11) forms a joint VP. When applying a wall panel to a wall, the joint vertical plane will typically be located horizontally, but since the embodiment shown in Fig. 2 is shown in a horizontal orientation, the expression joint vertical plane is used. The joint vertical plane typically forms the location where the upper contact surfaces (25, 26) face each other, and as such defines a gap or joint between two adjacent wall panels. It can be seen that the groove (10) and the sideways tongue (7) extend beyond said joint VP, and are each located on opposite sides of the joint vertical plane. This significantly facilitates the production of the groove (10) and the sideways tongue (7), but also facilitates a relatively simple laying and insertion of the sideways tongue (7) into the groove (10), which makes the design relatively user-friendly. It can also be seen in Fig. 2 that the width of the outer lower part (W-OBS) of the groove (10), as seen in a plane perpendicular to the joint vertical plane, is greater, and in this case at least twice as large as the width of the inner lower part (W-IBS) of the groove (10). The same applies to the width of the sideways tongue (W-ST), where it can be seen that the largest part of the width formed in Fig. 2 is located outside the joint vertical plane. The lowest surface of the groove (10) is formed by the lower lip (12) and is flat and substantially horizontal (perpendicular to the joint vertical plane) and is located on opposite sides of the joint vertical plane. The lower surface of the sideways tongue (7) is also preferably flat and is also located on opposite sides of the joint vertical plane. As shown, the lower surface of the sideways tongue (7) is preferably inclined upwards in the direction of the upper intermediate part (8). The inclined part is usually limited. The inclination is preferably between 0 and 5 degrees relative to the lower surface of the groove. This will facilitate the insertion of the tongue (7) into the groove (10).

Fig. 3 shows a schematic wall covering (100) with three wall panels (1). Fig. 3 shows a view of the decorative side, wherein the upper part of the sideways tongue (7) shows a part that is not connected to the next panel, and the lower part of the lower lip (12) shows the transition to the inner surface (13a) of the upwardly directed locking element (13), as well as the sides (13c) of the surface. Fig. 3 shows one embodiment in which six recesses (14) are used, distributed along the long side (4) of the panels (1).

Fig. 4 schematically shows the wall covering (100) shown in Fig. 3 in an inverted configuration with a sideways tongue (7) on the upper part and a lower lip (12) on the upper part.

Fig. 5 shows schematically a variation of Fig. 4. Instead of a series of recesses (14) in the upwardly directed locking element (13), the recess (14) is realized as a continuous groove running along the length of the panel (1).

Fig. 6 shows a schematic side view of three wall panels (1), wherein only the middle one of the panels (1) is shown in its entirety. When laying, the lower panel (1) is placed first and fixed to the supporting structure (17) by means of a screw (15) connecting the lower panel (1) to the supporting structure (17). Next, the middle panel (1') is tilted into the lower panel (1) by placing the sideways tongue (7) in the groove (10) and tilting the tongue (7) into the groove (10). When the middle panel (1') is aligned or is in the same plane as the lower panel (1), the middle panel (1') is also fixed to the supporting structure (17) by means of a screw (15). Now the groove (10) of the middle panel (1') is available for inserting the sideways tongue (7) of the upper panel (1'') and the process can be continued until the desired height is reached. The same process can be used but rotated 90 degrees if the panels are placed vertically instead of horizontally.

Fig. 7 shows a variation of the coating shown in Fig. 6. The variations can be applied to any panel in any configuration and are not limited to the embodiment shown, the principles being applied more widely. At the upper joint between the lower panel (1) and the middle panel (1') a first bevel (27) is shown. This bevel (27) is made by chamfering the decorative surface (2b) of the first panel (1), while the chamfer is not removed on the second panel (1'). In this way, the collection of liquid on the decorative surface (2b), dripping from the middle panel (1') onto the lower panel (1), prevents it from leaking through the joint, but instead directs it to the outer surface of the lower panel (1).

The second bevel (28) is shown at the middle joint between the middle panel (1') and the top panel (1''). This bevel (28) is made by chamfering the decorative surface (2b) of the middle panel (1') and the top panel (1''). This bevel (28) has a similar purpose, but looks different.

In the middle of the joint, the groove (10) of the middle panel (1') contains a channel (29) extending from the groove (10) to the back side (2a) of the wall panel for the flow of possible liquid collecting in the groove (10) to the back side (2a).

Fig. 8 shows schematically the connecting parts on the other sides of the panel, if such connecting parts are present. In this description, references are made to vertical and horizontal, which is true for the orientation of the connecting parts shown in Fig. 8. On the wall cladding of the panel

- 24 047521 the orientation may be mirrored or inverted, with the same changes applying to the terms used.

These connecting parts, as shown in Fig. 8, can be the third (31) and fourth (32) connecting parts, which are designed to be connected by a downward movement. The third connecting part (31) comprises an upwardly directed tongue (33), at least one upwardly directed side surface (34) lying at a distance from the upwardly directed tongue, and an upwardly directed groove (35) formed between the upwardly directed tongue and the upwardly directed side surface, wherein the upwardly directed groove is designed to accommodate at least a part of the downwardly directed tongue of the fourth connecting part of the other panel. The side (33a) of the upwardly directed tongue (33), facing the upwardly directed side surface (35), is the inner side of the upwardly directed tongue, and the side (33b) of the upwardly directed tongue, facing away from the upwardly directed side surface, is the outer side of the upwardly directed tongue.

The fourth connecting part (32) comprises a downwardly directed tongue (36), at least one downwardly directed side surface (47) lying at a distance from the downwardly directed tongue, and a downwardly directed groove (48) formed between the downwardly directed tongue and the downwardly directed side surface, wherein the downwardly directed groove is designed to accommodate at least a portion of the upwardly directed tongue of the first connecting part of the other panel. The side (36a) of the downwardly directed tongue facing the downwardly directed side surface is the inner side of the downwardly directed tongue, and the side (36b) of the downwardly directed tongue facing away from the downwardly directed side surface is the outer side of the downwardly directed tongue. The outer surface of the downwardly directed tongue and the upwardly directed side surface simultaneously comprise an upper contact surface (37, 38) near, or on, or next to, or in the direction of the upper side of the panel, wherein said contact surfaces extend vertically at least partially, and preferably completely, and wherein the upper contact surface of the outer surface of the downwardly directed tongue of said panel is designed with the possibility of engaging the upper contact surface of the upwardly directed side surface of the adjacent panel in the connected state of said panels.

The adjoining upper contact surfaces (37, 38) of both the downwardly directed tongue and the upwardly directed side surface comprise an inclined contact surface (39, 40), wherein the inclined contact surface of the downwardly directed tongue of the said panel is designed with the possibility of engaging with the inclined contact surface of the upwardly directed side surface of the adjacent panel in the connected state of the said panels, wherein each vertical part of the upper contact surface and each adjoining inclined surface mutually form an angle (a) from 100 to 175 degrees. The downwardly directed tongue adjoining the inclined contact surface (40) comprises an outer surface (41) located below the inclined contact surface of the downwardly directed tongue, and the upwardly directed side surface adjoining the inclined contact surface (39) comprises an inner surface (42) located below the inclined contact surface of the upwardly directed side surface, wherein the outer and inner surfaces extend substantially parallel and preferably extend substantially parallel and extend at least partially in the vertical direction. In the connected state there is an intermediate space (43) between at least part of the outer surface of the said panel and at least part of the inner surface of the adjacent panel.

The upper contact surfaces (37, 38) may form a plane, in the configuration shown a vertical plane (44), and a portion (45) of the downwardly directed tongue (36) may thus protrude from this plane (44).

Fig. 9 schematically shows a variation of the connecting parts as shown in Fig. 1-7. Reference numerals indicating the same or similar elements have the same reference numerals. Compared with the parts shown in Fig. 1-7, the recess (14) is provided with a second recess (46). The depth in these recesses can be significantly smaller, compared with the depth of the recess (14) and can be provided in a similar way with chamfered sides (47). The second recess (47) is shown in the center of the recess (14). This second recess (47) can be included in any of the embodiments shown in Fig. 1-7 and helps to guide a connecting element, such as a nail or a screw, used to connect or attach the panels to the surface.

Fig. 9 also schematically shows an intermediate space (23) between the rear side of the sideways tongue (7) and the lower lip (12), which is located between the locking surfaces (18, 19) and the outer surface or the outermost side of the sideways tongue (7), wherein the rear side of the sideways tongue (7) and the lower lip (12) are thus not in contact with each other in the connected state.

The above-described inventive ideas are illustrated by several illustrative embodiments. It is possible that individual inventive ideas can be applied without the use of

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Claims (19)

at the same time other details of the described example. It is not necessary to dwell in detail on examples of all conceivable combinations of the above-described inventive ideas, since it will be clear to a person skilled in the art that numerous inventive ideas can be (re-)combined to arrive at a specific application. It will be obvious that the invention is not limited to the working examples shown and described herein, but that numerous variations are possible within the scope of the appended claims, which will be obvious to those skilled in the art. The verb contain and its conjugations as used in this patent publication are understood to mean not only contain, but are also understood to mean the phrases consist, essentially consist of, formed by and their conjugations. CLAUSE OF THE INVENTION 1. A wall panel for forming a wall covering using a plurality of panels, comprising: a. a core comprising a back side, a decorative side opposite the back side, and at least two sides of said core comprising connecting parts for interconnecting several panels; b. wherein the connecting parts comprise at least one first connecting part and at least one second connecting part located on opposite sides of the core, wherein at least one first connecting part and at least one second connecting part are designed with the possibility of connecting by an inclined movement; c. wherein the first connecting portion comprises a laterally directed tongue, an upper intermediate portion for connecting the laterally directed tongue to the core and a downwardly directed groove for receiving at least a portion of the upwardly directed locking element, and d. wherein the second connecting part comprises a groove for receiving at least a portion of a laterally directed tongue, formed by the upper lip and the lower lip, extending from the core, wherein the upper surface of the lower lip forms the lower part of said groove, wherein the end portion of the lower lip is provided with an upwardly directed locking element, wherein the upwardly directed locking element has an inner surface facing the upper lip, an outer surface facing away from the upper lip, and an upper side between the inner surface and the outer surface, wherein the distal end of the upper lip forms a joint vertical plane, wherein the lower lip and said lower part of said groove extend beyond said joint vertical plane; e. wherein said upper side of the upwardly directed fixing element is provided with a recess extending at least partially through the upwardly directed fixing element for receiving at least one fastening element, such as a screw, for fixing the wall panel to the wall. 2. A wall panel according to any of the preceding claims, characterized in that the inner surface of the upwardly directed fixing element comprises first fixing surfaces, and the side of the sideways directed tongue facing the core comprises a second fixing surface, and the fixing surfaces interact to ensure fixation of the panels in a connected state. 3. A wall panel according to any of the preceding claims, characterized in that the side of the sideways tongue facing the decorative side comprises a third fixing surface, and the side of the upper lip facing away from the decorative side comprises a fourth fixing surface, and the fixing surfaces interact to ensure fixation of the panels in a connected state. 4. A wall panel according to any of the preceding claims, characterized in that the recess is provided with beveled edges, and preferably the recess in cross-section has essentially the shape of a truncated cone, widest on the decorative side, tapering towards the back side. 5. A wall panel according to any of the preceding claims, characterized in that the recess is located in the center of the upwardly directed fixing element, in particular between the inner surface and the outer surface of the upwardly directed fixing element. 6. A wall panel according to any of the preceding claims, characterized in that at least part of the side of the sideways tongue facing away from the upper intermediate part and/or at least part of the groove between the upper and lower lip is partially rounded. 7. A wall panel according to any of the preceding claims, characterized in that in the connected state there is an intermediate space between the side of the sideways directed tongue facing the back side and the lower lip, and the intermediate space narrows inward from the upwardly directed locking element. - 26 047521 8. A wall panel according to any of the preceding claims, characterized in that the width of the upwardly directed fixing element is smaller compared to the width of the upper intermediate part so that, preferably in the connected state, there is an intermediate space between the outer surface of the upwardly directed fixing element and the core of the other panel. 9. A wall panel according to any one of the preceding claims, characterized in that the first connecting part comprises a first upper contact surface between the decorative side and the sideways tongue, and wherein the side of the upper lip facing away from the core comprises a second upper contact surface, wherein the first and second upper contact surfaces are arranged so as to be in contact at least partially when connected. 10. A wall panel according to any one of the preceding claims, characterized in that the sideways tongue and groove are designed to apply a clamping force in the connected state to compress two connected panels together. 11. A wall panel according to any of the preceding claims, characterized in that the groove comprises a channel extending from the groove to the back of the wall panel. 12. A wall panel according to any one of the preceding claims, characterized in that the panel is elongated and is designed to be horizontally positioned to form part of a wall covering, wherein preferably the first and second connecting parts are located on the long sides of the panel, and/or wherein two other opposite sides of the wall panel are provided with third and fourth connecting parts, preferably designed to be connected by the same tilting movement as the first and second connecting parts. 13. A wall panel according to any of the preceding claims, characterized in that the panel is elongated and is designed to be vertically positioned to form part of a wall covering, wherein preferably the first and second connecting parts are located on the long side of the panel, and/or wherein two other opposite sides of the wall panel are provided with connecting parts. 14. A wall panel according to any of the preceding claims, characterized in that the panel is elongated, wherein the first and second connecting parts are located on the long side of the panel, and wherein along the long side there is a plurality of recesses, preferably evenly distributed along the long side. 15. A wall panel according to any of the preceding claims, characterized in that the recess in the upwardly directed fixing element forms a recessed groove running along one side of the wall panel, preferably the long side of the elongated panel. 16. A wall panel according to any one of the preceding claims, characterized in that the lower lip extends beyond the upper lip along a distance that is at least 2 times, preferably at least 3 times, more preferably about 4 times the thickness of the wall panel. 17. A wall panel according to any of the preceding claims, characterized in that in the connected state of two panels there is an intermediate space between the upper intermediate part of the first panel and the upwardly directed fixing element of the second panel, at least over the entire width of the upwardly directed fixing element, and the intermediate space continues between the distal end of the upwardly directed fixing element of the second panel and the core of the first panel. 18. A wall panel according to any one of the preceding claims, characterized in that the upwardly directed fixing element on the back side opposite the surface side comprises an adhesive layer, such as a thin layer of glue, for temporarily attaching the wall panel to the supporting surface. 19. A method for installing wall covering using wall panels according to any of the preceding claims, comprising the steps of: a. providing a first wall panel with first and second connecting portions on at least two opposite sides; b. attaching the first wall panel to the supporting surface, while leaving the second connecting portion of the first wall panel accessible; c. providing a second wall panel with first and second connecting portions on at least two opposite sides; d. placing the first connecting portion of the second wall panel in the second connecting portion of the first wall panel; e. tilting the second wall panel to align with the first panel, while leaving the second connecting portion of the second wall panel accessible; f. optionally repeating steps c-e with an additional panel. -