PANEL AND CLADDING.

Abstract

The last few decades have seen enormous progress in the flooring market. It is known to install flooring panels over an underlying floor in various ways. The present invention relates to an improved panel, such as a flooring panel, particularly a decorative flooring panel. The invention further relates to a covering, particularly a floor covering, comprising multiple interconnected panels according to the invention.

Description

The present invention relates to a panel, particularly a floor panel, and to a covering, particularly a floor covering, comprising multiple panels according to the invention. The last few decades have seen enormous progress in the flooring market for floor coverings. It is known to install floor panels over an underlying floor in various ways. It is known, for example, that floor panels are fixed to the underlying floor either by gluing or nailing them. This technique has the disadvantage of being quite complicated, and subsequent changes can only be made by removing the floor panels. According to an alternative installation method, the floor panels are installed loosely on the subfloor, such that the floor panels interlock with each other by means of a tongue-and-groove joint, and are mostly also glued together at the tongue and groove.The flooring obtained in this way, also called floating parquet flooring, has the advantage that it is easy to install and that the entire surface of the floor can be moved, which is often convenient in order to accommodate possible expansion and contraction phenomena. Flooring options and requirements have also evolved. While traditional flooring used to be made of wood or wood-based products, the market has recently shifted toward plastic-based panels, such as PVC panels, and even mineral-based panels, such as magnesium oxide panels. Each of these alternatives has its advantages and disadvantages. One disadvantage is that it can be difficult to fit and interlock the panels together, creating a watertight seal. Therefore, one objective of the present invention is to provide an improved connection between panels, in particular a waterproof connection. The present invention provides a panel, in particular a floor panel, comprising: at least a first coupling part and at least a second coupling part arranged on opposite sides of the panel, wherein the first coupling part and the second coupling part of another panel are arranged to couple with a downward movement;wherein the first coupling part comprises an upward tongue, at least one upward side located at a distance from the upward tongue, and an upward groove formed between the upward tongue and the upward side, wherein the upward groove is adapted to receive at least a portion of a downward tongue of a second coupling part of another panel, wherein the side of the upward tongue facing the upward side is the inside of the upward tongue and the side of the upward tongue opposite the upward side is the outside of the upward tongue;wherein the second coupling part comprises a downward tongue, at least one downward side located at a distance from the downward tongue, and a downward groove formed between the downward tongue and the downward side, wherein the downward groove is adapted to receive at least a portion of an upward tongue of a first coupling part of another panel, wherein the side of the downward tongue facing the downward side is the inside of the downward tongue and the side of the downward tongue opposite the downward side is the outside of the downward tongue;wherein the downward-facing outside of the tongue and the upward-facing side both comprise an upper contact surface near, in, contiguous to, or towards an upper side of the panel, the upper contact surfaces of which are in contact in the coupled state of the panels, and wherein at least one upper contact surface preferably extends vertically at least partially; wherein the upward-facing outside of the tongue comprises a first outwardly projecting engagement element and wherein the lower side is provided with a second cavity-shaped engagement element, wherein at least a portion of the first and at least a portion of the second engagement element is in contact in the coupled state of the panels and forms a surface of the engagement element;wherein the exterior of the outward protrusion comprises an upper portion and an adjacent lower portion, wherein the lower portion comprises an inclined engagement surface and the upper portion comprises a preferably curved guide surface; wherein the cavity comprises an upper portion and an adjacent lower portion, wherein the lower portion comprises an inclined engagement surface; wherein the parts of the first and second engagement element that are in contact, in the coupled state of the panels, are the inclined engagement surfaces of the engagement elements and / or wherein, in the coupled state of the panels, the upper portions of the first and second engagement elements are at least partially separated. It should be noted that, in describing the invention, terms such as top, bottom, upper, lower, horizontal, and vertical are used based on a floor configuration, with the upward-facing side being the top or upper side, the subfloor side being the lower or lower side, and the panels lying horizontally or in a horizontal plane. When used as wall cladding, the panels are typically mounted vertically, which is also possible with the panels according to the present invention. The side facing the wall is the lower side, the side facing the room is the top side, and the vertical and horizontal orientations are reversed. The wall panels themselves can also be evaluated when they are on the floor, as if they were floor panels.The same applies to ceiling coverings, where the panels are mounted on the ceiling, which is also possible with the panels according to the present invention. The top and bottom portions are then flipped over. The ceiling panels themselves can also be evaluated when they are on the floor, as if they were floor panels. The mating parts of two panels interact and provide an interlocking mechanism, typically in a vertical and horizontal direction. The upward-facing tongue fits into the downward-facing groove, and the downward-facing tongue fits into the upward-facing groove, providing an interlocking mechanism in the plane of the panel or in the horizontal direction for flooring, for example. Preferably, at least part of the interior, and more preferably the entire interior, from the upper tongue upwards slopes upwards to the side, and at least part of the interior, and more preferably the entire interior, from the lower tongue downwards slopes downwards to the side. Typically, this results in the beneficial effect of the upper tongue being at least partially surrounded and secured, and possibly held, by the lower groove, and the lower tongue being at least partially surrounded and secured, and possibly held, by the upper groove. The panels are typically arranged to interlock with a downward motion. This motion is also referred to as a pull-down or pull-up motion, and may mean that a new panel can be pushed into an already positioned panel. Such interlocking is also possible when the panels are connected by a rack and pinion or scissor motion. Alternatively, the panels can be arranged to interlock with a tilting (downward) motion. This motion may also be referred to as a rotational motion, where a portion of a new panel is inserted into a portion of a panel already in place and fully inserted by means of a tilting motion. In a preferred embodiment, the panel comprises at least a third-to-one coupling portion and at least a fourth-to-one coupling portion arranged on another pair of opposite sides of the panel.wherein the third coupling portion of said panel and the fourth coupling portion of another panel are preferably arranged to couple by means of a downward tilting motion. Preferably, the third coupling profile comprises: a side tab extending in a direction substantially parallel to the upper side of the core, at least a second downward side located a distance from the side tab, and a second downward groove formed between the side tab and the second downward side, and wherein the fourth coupling portion comprises: a third groove configured to accommodate at least a portion of the side tab of the third coupling profile of an adjacent panel, said third groove being defined by an upper flange and a lower flange, wherein said lower flange is provided with an upward locking element,wherein the third coupling part and the fourth coupling part are configured so that two such panels can be coupled together by means of a twisting motion, wherein, in the coupled state: at least a portion of the side tab of a first panel is inserted into the third groove of an adjacent second panel, and wherein at least a portion of the upward-facing locking element of said second panel is inserted into the downward-facing second groove of said first panel. To form a tight connection at the top, the panels are in contact at their upper contact surfaces. Preferably, these upper contact surfaces are substantially flat and parallel, and both contact surfaces can extend vertically to increase the contact area. It can often be advantageous for at least one upper contact surface to be slightly inclined with respect to a vertical plane, wherein at least one slightly inclined contact surface and the vertical plane preferably enclose an angle of between 0 and 2 degrees, preferably between 0 and 1 degree, more preferably between 0 and 0.5 degrees, and even more preferably between 0 and 0.3 degrees.Preferably, the upper contact surface of the downward-facing tongue extends vertically, and the upper contact surface of the upward-facing side slopes downward in the opposite direction to the upward-facing tongue. Preferably, and more preferably, the vertical upper contact surface of the downward-facing tongue and the inclined upper contact surface of the upward-facing side mutually enclose an angle of between 0 and 2 degrees, preferably between 0 and 1 degree, more preferably between 0 and 0.5 degrees, and even more preferably between 0 and 0.3 degrees. Furthermore, it is conceivable that the upper contact surface of the upward-facing side extends vertically, and the upper contact surface of the downward-facing tongue slopes downward in a downward-facing direction.Preferably, the downward-sloping upper contact surface of the tongue and the upward-sloping vertical upper contact surface of the side panel mutually enclose an angle of between 0 and 2 degrees, preferably between 0 and 1 degree, more preferably between 0 and 0.5 degrees, and even more preferably between 0 and 0.3 degrees. Additionally, it is conceivable that each of the downward-sloping upper contact surface of the tongue and the upward-sloping upper contact surface of the side panel is at least partially inclined with respect to a vertical plane (i.e., a plane perpendicular to the panels). This inclination is preferably such that both upper contact surfaces are inclined downwards in opposite directions towards each other.One technical effect of these configurations is that the upper seam formed between the panels allows for more intense contact between the upper contact surfaces, thus promoting the creation of a hermetic barrier. Furthermore, the aforementioned slope typically reduces sensitivity to tolerances and improves accuracy during manufacturing and assembly. The slightly sloped upper contact surface prevents creaking between the interlocking panels. The slope also allows for a better or stronger connection of the mated panels at the top, where the panels are configured to be in full contact when joined. The upper contact surfaces are not necessarily the top surfaces of the panels; for example, panels can have a chamfered or beveled top surface, or a grout line, which provides a decorative function. Preferably, the upper contact surfaces are the top surfaces where two panels meet. Furthermore, in one embodiment, the exterior of the downward-facing tongue comprises between the upper contact surface and the inclined contact surface of the downward-facing tongue at least one cavity, preferably trapezoidal in shape, wherein, in the coupled state of the adjacent panels, said cavity is preferably positioned at a distance from the upper contact surface of the upward-facing side. This cavity allows for the expansion or swelling (locally) of the panel material, preventing disruption or dislocation of the connection between two interlocking panels. The cavity also functions as an additional dust chamber, preventing dust from interfering with the contact of the upper contact surfaces. The cavity can be located between the upper contact surface of the down-tab and an inclined contact surface and / or a third down-tab locking element, or at the transition between the upper contact surface and the inclined contact surface and / or the third down-tab locking element. Preferably, the panels, or the panel coupling parts, are configured to exert a certain locking force in the coupled state, forcing the panels together. Such a locking force can be achieved, for example, by a prestressing configuration or by slightly oversizing one coupling part compared to the other. In the 5 qq l Lnn / rznz / E / γΐΛΐ floor panels, this creates a force in the horizontal direction or in the plane of the floor panel. This locking force preferably pushes the panels towards each other in the main plane of the panels and thus pushes the upper contact surfaces together, where this prestressing improves the connection between the panels and preferably creates a watertight seal on the top of the panels. It is conceivable that, due to the engagement or clamping force, the area or zone on or around the downward-facing inclined contact surface of the tongue may deform elastically or plastically during the mating of adjacent inclined contact surfaces. The extent of the deformation typically depends on the panel material characteristics and the specific design of the mating parts. The outer portion of the upward-facing tongue comprises a first locking element, for example, in the form of an outward-facing protrusion, and the downward-facing side may be provided with a second locking element, for example, in the form of a cavity, in which at least a portion of the first and at least a portion of the second locking element are in contact when the panels are in the coupled state and form a locking element surface. The two locking elements can therefore act together to provide a locking mechanism, in particular a locking mechanism in a vertical direction or perpendicular to the (main) plane of the panels. The first and second locking elements are preferably integrally formed with the panel and, for example, can be milled from the panel material. The application of the mutually acting locking elements prevents substantial vertical displacement of the two panels relative to each other.Preferably, the first or second locking element, or both, are substantially rigidly connected to the rest of the panel, respectively, so that a strong and relatively durable locking mechanism can be achieved, since relatively weak elastic locking parts, where material fatigue could occur relatively quickly, are not used. The first locking element can form an integral part of the up-tab, where the first locking element can be formed, for example, by a deformation of the projecting (outward-protruding) or recessed (inward-protruding) edge of the up-tab. The first engagement element may be an outward-facing protrusion, wherein the exterior of the outward-facing protrusion comprises an upper portion and an adjacent lower portion, wherein the lower portion comprises an inclined engagement surface and the upper portion comprises a guide surface, preferably curved. The first engagement element, on the exterior of the upward-facing tongue, will, during coupling, meet the downward-facing side of another panel, as it is the protruding portion of the panel and, typically, the outermost portion of the panel on one side, and it is necessary to overcome the forces during coupling to force one panel against the other. By providing a (curved) guide surface on the upper portion, the additional panel or other panel is guided downwards, so that coupling can occur gradually and large material deformations and / or peak stresses can be avoided.The lower portion can therefore be inclined and forms the portion of the protrusion that curves upward from the outermost part of the protrusion towards the tongue. Furthermore, this inclined surface provides a guiding function, directing the panels to their final position. The inclination of the engagement surface also allows a potential upward force or movement of the panels to result in a vertical and horizontal force component. The horizontal component can be used to hold the panels together, forcing them towards each other to improve the connection and the watertight properties of the joint between the panels. The second engagement element can be a cavity comprising an upper portion and an adjacent lower portion, wherein the lower portion comprises an inclined engagement surface, designed to work in conjunction with the first engagement element.Inclined surfaces also have the advantage, for example over rounded surfaces, of being relatively easy to manufacture or mill, and of allowing a relatively large contact area between them to distribute the engagement forces across the mating panels. Preferably, each inclined engagement surface defines a plane (flat surface), the plane of which forms a fold or twist with the curved upper portion of the corresponding engagement element. Preferably, this plane is positioned parallel to the plane formed by the inclined contact surface of the panel. For smooth guidance, it is preferred that for the upward-facing tongue: the outer edge of the upward-facing tongue extends vertically downward and upward to the outward-facing protrusion.The intersection of the upper portion of the outward protrusion and the vertical exterior of the upward tongue comprises a fold or twist. Said outward protrusion preferably consists of a curved upper portion whose curve gradually flattens near the lower area of ​​the upper portion to substantially vertical. The upper portions extend downward to the lower portion, the lower portion of which consists of a flat, inclined engagement surface. The inclined engagement surface forms a fold or twist with the flattened lower area of ​​the upper portion of the outward protrusion. The cavity in the downward side is preferably complementary (form-fit) to the outward protrusion, and therefore the upward side preferably comprises a vertical outer portion extending from the upper surface of the downward groove to the cavity.The inwardly oriented cavity comprises a curved upper portion whose curve gradually flattens near the lower area of ​​the upper portion, preferably becoming substantially vertical. The inclined engagement surface forms a fold or twist with the flattened lower area of ​​the upper portion of the cavity. These inclined engagement surfaces have substantially the same angle of inclination with respect to a vertical plane. Preferably, in the coupled state of adjacent panels, the upper portions of the first and second locking elements are completely separated. Typically, this results in the situation where, in the coupled state of adjacent panels, the outward protrusion and the cavity engage only with each other via their angled locking surfaces. In this way, the functionality and effectiveness of the angled locking surfaces can be enhanced. Preferably, in the coupled state of adjacent panels, only a portion of the angled locking surface of the lower portion of the outward protrusion engages only a portion of the angled locking surface of the lower portion of the cavity.Preferably, the length of the inclined engagement surface of the lower portion of the outward protrusion is greater, preferably at least 1.5 times greater, than the inclined engagement surface of the lower portion of the cavity. Preferably, the upper outer portion is substantially vertical and defines an outer vertical plane, wherein at least a part of the first locking element projects horizontally from the outer vertical plane, preferably by a maximum of 2 mm, more preferably by a maximum of 1 mm. The outer vertical plane typically divides the upward-facing tongue into an inner section directed upwards and an outer section comprising the first locking element, wherein the maximum width of the inner section is preferably at least 8 times, preferably at least 10 times, the maximum width of the outer section. The first and second locking elements are preferably located below the level of the inclined contact surfaces (if applicable) and / or the third and fourth locking elements (if applicable) of the down-tab and up-side. This typically reduces the degree of deformation of the mating parts during the mating process, thus promoting the service life and reliability of the mating parts. Preferably, the level of the inclined contact surfaces of the down-tab and up-side is above the level of the highest point of the up-tab. This is typically advantageous for creating a watertight barrier as close as possible to the top surface of the panels. Preferably, at least a portion of the upper part of the outward-facing protrusion located on the outside of the upward-facing tongue is positioned at a higher level than a level defined by the lowest point of the upward-facing groove, and preferably, at least a portion of the upper part of the cavity located on the downward-facing side is positioned at a higher level than a level defined by the lowest point of the upward-facing groove. The inclined contact surfaces of said protrusion and cavity are preferably located below the lowest point of the upward-facing groove. Typically, this facilitates the coupling process, but it can also be advantageous for uncoupling interconnected panels by means of a downward-facing outward tilting motion relative to the panels. The upper portion can extend over a larger vertical section compared to the lower portion, gradually guiding the panels into place. The upper portion typically does not provide a vertical locking effect (because the upper portions of the protrusion and outward-facing cavity preferentially separate when mated), so the horizontal portions of the locking elements are less relevant compared to the lower portion, which typically provides a vertical locking effect. The parts of the first and second locking elements that are in contact, in the mated state of the panels, are typically formed by the inclined locking surfaces of the locking elements, i.e., by the lower portions. In the mated state of the panels, the upper portions of the first and second locking elements may separate at least partially.This separation allows the upward tongue to move upwards without being hindered by the downward side, whose upward movement can in turn be transferred and translated into a horizontal closing movement to improve the connection or engagement of the panels, forcing the panels together. The exterior of the upward-facing tab may comprise an upper outer portion and a lower outer portion, wherein the first engagement element is disposed between the lower and upper outer portions, with the lower outer portion being closer to the inside of the upward-facing tab compared to the upper outer portion. The upper outer portion may preferably be substantially vertical and defines an external vertical plane, wherein the first engagement element projects at least partially from the external vertical plane, preferably by a maximum of 2 mm. For example, the upper outer portion above the first engagement element defines one vertical plane and the lower outer portion below the first engagement element defines another vertical plane, which are parallel but offset, with the vertical plane of the lower outer portion located closer to the upward-facing side.This difference creates a relatively large distance between the panels at the intersection between the upward-sloping hooking surface of the tongue and the lower outer portion, allowing for a greater upward tilt or rotational movement of the tongue upward and thus a potentially greater closing force or tension exerted by the hooking elements to improve the connection and waterproof properties of the panels. The lower outer portion can be substantially vertical, and the inclined engagement surface, or the lower portion and the lower outer portion, enclose an angle between 100 and 175 degrees, particularly between 100 and 150 degrees, and more specifically between 110 and 135 degrees. This angle has been shown to provide the best combination of engagement and guiding properties. The angle enclosed by the upper contact surfaces and the inclined contact surfaces, and the angle enclosed by the lower outer portion and the inclined engagement surface, or the lower portion, can differ by up to 20 degrees and is preferably the same. This allows for relatively easy manufacturing where identical or similar tools can be used to mill both elements of a panel. A more external portion of the first locking element can be positioned horizontally lower than the groove above it. This way, during the downward movement of the panels during coupling, the outermost or wider portion of the first locking element engages relatively late, facilitating the coupling of two panels. Preferably, lower down and preferably adjacent to the upper contact surfaces of the down tab and the up side, the exterior of the down tab comprises a third locking element and the up side comprises a fourth locking element, wherein, in the coupled state of the adjacent panels, at least a portion of the third locking element of said panel and at least a portion of the second locking element of another panel are in contact to effect a locking effect, preferably a vertical locking effect, of the panels with respect to each other. Preferably, in the coupled state of the adjacent panels, the upper contact surfaces define an inner vertical plane, wherein the third locking element and the fourth locking element are positioned on the same, and more preferably only, side of said inner vertical plane opposite the up tab.Preferably, the third and fourth locking elements extend a maximum of 1 mm, preferably a maximum of 0.5 mm, and more preferably a maximum of 0.2 mm, horizontally with respect to the inner vertical plane. Each of the third and fourth locking elements may comprise a protrusion and / or a cavity, wherein, preferably, the third locking element comprises a protrusion, and the fourth locking element comprises a cavity. Preferably, the level of the third and fourth locking elements is above the level of the highest point of the upward-facing tongue, which reduces material deformation and therefore material stress during coupling and uncoupling. Preferably, the first and second locking elements are located at a level below the level of the third and fourth locking elements, which further reduces material deformation and therefore material stress during coupling and uncoupling. The exterior of the down-profile tongue preferably comprises, between the upper contact surface and the third engagement element of the down-profile tongue, at least one cavity, wherein, in the coupled state of the adjacent panels, this cavity is preferably positioned at a certain distance from the upper contact surface of the up-profile side. This cavity allows for (local) expansion or swelling of the panel material, preventing disruption or dislocation of the connection between two interlocking panels. The cavity also functions as an additional dust chamber, preventing dust from interfering with the contact of the upper contact surfaces. The cavity may be located between the upper contact surface of the down-profile tongue and the third engagement element of the down-profile tongue, or at the transition between the upper contact surface and the third engagement element. Adjacent to, and typically directly adjacent to or directly below, the upper contact surfaces, there may be a sloped contact surface. At the sloped surfaces, the panels are in contact, creating a connection or seal between them. The slope is preferably angled so that, looking down at the tongue, the sloped surface extends outward, and looking up at the side, the sloped surface extends inward. The slope angle functions so that the down-facing tongue has a projecting portion and the up-facing side has a recessed portion, which, in the mated state, are in contact and thus provide a vertical interlocking effect. The slope also creates a slight labyrinth, which enhances the watertight properties of the connection. Preferably, the inclined contact surface of the downward-facing tongue extends a maximum of 1 mm, preferably a maximum of 0.5 mm, and more preferably a maximum of 0.2 mm, horizontally with respect to an interior vertical plane defined by (a contact portion of) the upper contact surfaces of two panels in the mated state. Preferably, the level of the inclined contact surfaces of the downward-facing tongue and the upward-facing side is above the level of the highest point of the upward-facing tongue. This reduces material stress during the mating process, thereby improving the reliability and durability of the mating of adjacent panels. Typically, the inclined contact surface of the downward-facing tongue defines at least a portion of the third mating element, and the inclined contact surface of the upward-facing side defines at least a portion of the fourth mating element.Contiguous to, and typically directly contiguous to or directly below the inclined contact surface, the down-tab may comprise an outer surface. This outer surface may be, for example, the outermost surface of the down-tab, or the outermost surface of the down-tab furthest from the down-side. Similarly, contiguous to, and typically directly contiguous to or directly below the inclined contact surface, the up-side comprises an inner surface. Between the inner and outer surfaces, a gap is present. This gap is intended to prevent any force exerted on or by the panels from resulting in the panels being pushed against each other at any location other than the upper contact surfaces and / or inclined contact surfaces.If the inner and outer surfaces were in contact, they could prevent the upper contact surfaces from meeting, which would compromise the waterproof properties of the connection. Therefore, at the top, on the upper contact surfaces and the angled contact surfaces, the aim is to create a connection between the panels, while below these contact surfaces, the aim is to prevent such a connection. The upper contact surfaces may be at least partially vertical and define an inner vertical plane, where the downward-angled tongue contact surface extends beyond the inner vertical plane, preferably by a maximum of 1 mm horizontally, and where the upward-angled side contact surface is set back from the inner vertical plane.Such a configuration is such that the downward-facing tongue 12 qq l Lnn / eznz / E / YiAi protrudes locally from the inner vertical plane, and the upward-facing side is locally recessed, where, in the engaged state, the inclined contact surfaces can engage each other from behind to create a vertical locking effect. By limiting the horizontal extension of the protrusion, the downward-facing tongue can still be engaged with a downward or vertical movement while providing the vertical locking effect. A portion of the downward-facing tongue can therefore extend beyond the inner vertical plane, which portion can be lengthened with a larger vertical portion compared to the horizontal portion, where preferably the vertical portion is at least three times the horizontal portion. This allows for a relatively small horizontal portion, so that the panels can still be engaged with a vertical or downward movement. A downward-facing portion of the tongue can therefore extend beyond the inner vertical plane, where this portion can be substantially trapezoidal or wedge-shaped. This shape allows the portion, when subjected to any locking, coupling, or other force in the plane of the panels, to be wedged into the space provided on the upward-facing side, while simultaneously providing a robust portion capable of withstanding forces, thus creating a tight connection between the panels. This, in turn, improves the watertight properties of the panel connection. The inclined contact surfaces can be located outside and / or adjacent to the inner vertical plane, and preferably are located entirely outside the inner vertical plane or entirely on one side of it. This allows for a relatively simple construction that provides a tight connection between two panels. Preferably, the upper contact surfaces, which define the vertical plane, transition directly to the inclined contact surfaces. In this configuration, the connection of the contact surfaces continues from the upper contact surfaces to the inclined contact surfaces, increasing the uninterrupted surface area and thus improving the connection between the panels and the waterproofing properties of the joint. In the mated state, the downward-facing lower portion of the tongue can make contact with the upward-facing upper portion of the groove on a groove contact surface. A gap is present between the first and second mating parts, extending from the inclined contact surfaces to the groove contact surface. This gap can be used to collect, for example, dust or shavings from the panels, which may be generated during the mating of two panels. Additionally, this gap is intended to prevent any force exerted on or by the panels from causing them to push against each other at any point other than the upper and / or inclined contact surfaces.The contact surface of the groove is preferably primarily horizontal and allows the forces exerted on the panel, and in particular on the connection between two panels, typically in a downward direction when the panel is stepped on, to be transferred to the subfloor or surface beneath the panels. It is preferred that the up-groove and down-groove be shaped so that the gap between the contact surface of the groove and the outward surface of the underside of the down-groove spans a gap width that extends over at least one-quarter of the groove width, more preferably at least one-third, and even more preferably more than half of the groove width. This groove width is defined by the smaller horizontal width between the outer surface of the up-groove and the up-groove side. An upward-facing tongue and a downward-facing groove can, in the mated state, be separated from each other, creating a gap between the two surfaces. This gap is intended to prevent any force exerted on or by the panels from causing them to push against each other at any point other than the upper contact surfaces and / or inclined contact surfaces. An upward movement of the tongue can result, for example, in a horizontal force that closes or tightens the connection between two panels, particularly in so-called closed-groove interlocking connections. The gap between the upward-facing tongue and the downward-facing groove is provided to allow for this upward movement.The upper surface of the downward-facing groove can be formed, for example, by the lower surface of a bridge portion that connects the downward-facing tongue to the rest of the panel. The upper contact surface and the upward-sloping side contact surface can mutually enclose a first angle, and the upper contact surface and the downward-sloping tongue contact surface can mutually enclose a second angle, wherein the first and second angles differ by more than 20 degrees. For example, the upward-sloping side contact surface can mutually enclose a first angle of 120 degrees, and the upper contact surface and the downward-sloping tongue contact surface can mutually enclose a second angle of 125 degrees. The difference between the two angles is 5 degrees, which is within 20 degrees, as it is less than 20 degrees.By creating a difference between the angles, a configuration can be provided in qq l Lnn / rznz / E / γALA where a wedge action can be achieved to increase the engagement forces and waterproof properties of the connection. Pushing or fitting the engagement elements together can result in increased engagement forces or connections in the panels. Preferably, in the coupled state of adjacent panels, a gap is present between at least a portion of the outer surface of one panel and at least a portion of the inner surface of an adjacent panel. Preferably, the outer portion of the upward-facing tongue comprises an upper outer portion that defines an outer vertical plane dividing the upper tongue into an inner section directed sideways upward, and an outer section comprising the first locking element, wherein the maximum width of the inner section is at least 8 times, preferably at least 10 times, the maximum width of the outer section. This results in a limited effective width of the first locking element, facilitating the coupling process and reducing the degree of material deformation during coupling, thereby enhancing the reliability and durability of the interconnected panels. The panels according to the invention are made, for example, at least partially, of magnesium oxide, or are based on magnesium oxide. The panel according to the invention may comprise: a core provided with an upper side and a lower side, a decorative upper structure (or top section) fixed, either directly or indirectly, onto 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 a magnesia cement. Particles, in particular silicone-based and / or cellulose-based particles, may be dispersed in said magnesia cement. Optionally, one or more reinforcing layers, such as fiberglass layers, may be embedded in said composite layer.The core composition may further comprise magnesium chloride leading to a magnesium oxychloride (MOC) cement and / or magnesium sulfate leading to a magnesium oxysulfate (MOS) cement. It was found that applying a composition based on magnesium oxide and / or magnesium hydroxide, and in particular a magnesia cement, including MOS and MOC, significantly improves the flammability (non-combustibility) of the decorative panel. Furthermore, the relatively fire-resistant panel also exhibits significantly improved dimensional stability when subjected to temperature fluctuations during normal use. Magnesia-based cement is a cement made from magnesium oxide, where the cement is the product of a chemical reaction in which magnesium oxide acts as one of the reactants. qq l Lnn / rznz / E / γΐΛΐ In magnesia cement, magnesia may still be present and / or have undergone a chemical reaction forming a different chemical bond, as will be explained in more detail below. Further advantages of magnesia cement, compared to other types of cement, are presented below. One key advantage is that magnesia cement can be manufactured in a relatively energy-efficient and therefore cost-effective manner. Additionally, magnesia cement has relatively high compressive and tensile strength. Another advantage of magnesia cement is its natural affinity for cellulose materials, typically inexpensive, such as plant fibers, wood dust (sawdust), and / or wood chips. This not only improves the bonding properties of magnesia cement but also leads to weight savings and increased sound insulation (damping).Magnesium oxide, when combined with cellulose and optionally clay, creates magnesium vapor-respiring cements. This cement does not deteriorate (rot) because it efficiently expels moisture. Furthermore, magnesium cement is a relatively good insulating material, both thermally and electrically, making the panel particularly suitable for paving radar stations and hospital operating rooms. An additional advantage of magnesium cement is its relatively low pH compared to other types of cement, which allows for greater durability of fiberglass, whether as particles dispersed in the cement matrix and / or (as fiberglass) as a reinforcing layer. It also allows for the durable use of other types of fibers. Finally, a further advantage of the decorative panel is its suitability for both interior and exterior applications. As previously mentioned, magnesia cement is based on magnesium oxide and / or magnesium hydroxide. Magnesia cement itself may be magnesium-free, depending on the additional reagents used in its production. For example, it is quite conceivable that the magnesia used as a reagent might be converted into magnesium hydroxide during the production process. Therefore, magnesia cement may contain magnesium hydroxide. Typically, magnesia cement also contains water, specifically hydrated water. Water is commonly used as a binder to create a strong and cohesive cement matrix. Magnesia-based compositions, particularly magnesia cement, may include magnesium chloride (MgCh). Typically, when magnesia (MgO) is mixed with magnesium chloride in an aqueous solution, a magnesia cement comprising magnesium oxychloride (MOC) will be formed. The bonding phases are Mg(OH)₂, 5Mg(OH)₂.MgC₁₂.8H₂O (form 5), qq l Lnn / rznz / E / γΐΛΐ MOC is composed of 3Mg(OH)₂.MgCb.8H₂O (form 3) and Mg₂(OH)ClCO.3*3H₂O. Form 5 is the preferred phase because it has superior mechanical properties. Compared to other cement types, such as Portland cement, MOC has superior properties. MOC does not require moist curing, has high fire resistance, low thermal conductivity, and good abrasion resistance. MOC cement can be used with various aggregates (additives) and fibers with good bond strength. It can also receive different surface treatments. MOC develops high compressive strength within 48 hours (e.g., 8,000–10,000 psi). The increase in compressive strength occurs early during curing—the strength at 48 hours will be at least 80% of the maximum strength. The compressive strength of MOC is preferably between 40 and 100 N / mm². The flexural tensile strength is preferably 10-17 N / mm2.The surface hardness of MOC is preferably 50-250 N / mm². The E-modulus is preferably 1-3 x 10⁴ N / mm². The flexural strength of MOC is relatively low, but it can be significantly improved by the addition of fibers, particularly cellulose-based fibers. MOC is compatible with a wide variety of plastic fibers, mineral fibers (such as basalt fibers), and organic fibers such as bagasse, wood fibers, and hemp. The MOC used in the panel according to the invention can be enriched with one or more of these types of fibers. MOC does not shrink, is acceptably resistant to abrasion and wear, and is resistant to impact, indentation, and scratching. MOC is resistant to heating and freezing-thawing cycles and does not require air entrainment to improve durability.MOC also has excellent thermal conductivity, low electrical conductivity, and excellent bonding to a variety of substrates and additives, and it has acceptable fire resistance properties. MOC is less preferable if the panel is exposed to relatively extreme climatic conditions (temperature and humidity), which affect both the setting properties and the development of the magnesium oxychloride phase. Over time, atmospheric carbon dioxide reacts with the magnesium oxychloride to form a surface layer of Mg₂(OH)ClCO₃·3H₂O. This layer serves to retard the leaching process. Finally, further leaching results in the formation of hydromagnesite, 4MgO·3CO₃·4H₂O, which is insoluble and allows the cement to maintain its structural integrity. Magnesium-based compositions, and in particular magnesia cement, can be based on magnesium sulfate, specifically the mineral epsomite sulfate heptahydrate (MgSO4·7H2O). This latter salt is also known as Epsom salt. In aqueous solution, MgO reacts with MgSO4, leading to magnesium oxysulfate cement (MOS), which has very good bonding properties. In MOS, Mg(OH)2·MgSO4·8H2O is the most common chemical phase. Although MOS is not as strong as MOC, it is more suitable for fire-resistant applications because it begins to decompose at temperatures more than twice as high as MOC, providing longer-lasting fire protection. Furthermore, its decomposition products at high temperatures are less harmful (sulfur dioxide) than those of oxychloride (hydrochloric acid) and, in addition, less corrosive.Furthermore, climatic conditions (humidity, temperature, and wind) during application are not as critical for MOS cement as they are for MOC cement. The mechanical strength of MOS cement depends primarily on the type and relative content of the crystalline phases in the cement. Four basic magnesium salts have been found to contribute to the mechanical strength of MOS cement in the MgO MgSO4 H2O system at different temperatures between 30 and 120 degrees Celsius: 5Mg(OH)2-MgSO4-3H2O (phase 513), 3Mg(OH)2-MgSO4-8H2O (phase 318), Mg(OH)2-2MgSO4-3H2O (phase 123), and Mg(OH)2MgSO4-5H2O (phase 115). Typically, phase 513 and phase 318 could only be obtained by curing the cement under saturated steam conditions when the molar ratio of MgO and MgS₄ was set at (approximately) 5:1. Phase 318 has been found to contribute significantly to mechanical strength and is stable at room temperature and is therefore preferred to be present in the applied MOS.This also applies to phase 513. Phase 513 typically has a (micro)structure comprising a needle-like structure. This can be verified by SEM analysis. Magnesium oxysulfate (5Mg(OH)2-MgSO4-3H2O) needles can form substantially uniformly and typically have a length of 10–15 pm and a diameter of 0.4–1.0 pm. When referring to a needle-like structure, it can also mean a flake-like structure and / or a whisker-like structure. In practice, it does not appear feasible to obtain MOS comprising more than 50% of phase 513 or 318, but adjusting the composition of the crystalline phase can be applied to improve the mechanical strength of the MOS. Preferably, the magnesia cement comprises at least 10%, preferably at least 20% and more preferably at least 30% of 5Mg(OH)2*MgSO4*3H2O (phase 513).This preferred modality will provide a magnesia cement that has sufficient mechanical strength for use in the core layer of a floor panel. The crystalline phase of MOS is adjustable by modifying the MOS with 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 18 qq l Lnn / rznz / E / γΐΛΐ MOS using citric acid. Phase 517 can be obtained by modifying MOS using phosphoric acid and / or phosphates (H3PO4, KH2PO4, ksPCl, and k2HPO4). This phase 515 and phase 517 can be determined by chemical element analysis, where SEM analysis demonstrates that the microstructure of both phase 515 and phase 517 is a needle-like crystal, which is insoluble in water. In particular, the compressive strength and water resistance of MOS can be improved by the addition of citric acid. Therefore, it is preferred that the MOS, if applied in the panel according to the invention, comprises 5 Mg(OH)2.MgSO4.5H2O (phase 515) and / or Mg(OH)2*MgSO4*7H2O (phase 517). As mentioned earlier, adding phosphoric acid and phosphates can extend the setting time and improve the compressive strength and water resistance of MOS cement by changing the MgO hydration process and phase composition.Here, phosphoric acid or phosphates ionize in solution to form H₂PO₄⁻, HPO₄²⁻, and / or PO₄³⁻, where these anions adsorb onto fMg(OH)(H₂O)ₓ to inhibit the formation of Mg(OH)₂ and further promote the generation of a new magnesium subsulfate phase, leading to the compact structure, high mechanical strength, and good water resistance of MOS cement. The improvement resulting from the addition of phosphoric acid or phosphates to MOS cement follows the order H₃PO₄ = KH₂PO₄⁻ >> K₂HPO₄⁻ >> K₃PO₄⁻. MOS has better volumetric stability, less shrinkage, better bonding properties, and lower corrosivity over a significantly wider range of climatic conditions than MOC and may therefore be preferred. The density of MOS typically ranges from 350 to 650 kg / m³. The flexural tensile strength is preferably 1-7 N / mm2. The composition of magnesium cement preferably comprises one or more silicone-based additives. Various silicone-based additives may be used, including, but not limited to, silicone oils, neutral-cure silicones, silanols, silanol fluids, silicone (micro) spheres, and mixtures and derivatives thereof. Silicone oils include liquid polymerized siloxanes with organic side chains, including, but not limited to, polymethylsiloxane and derivatives thereof. Neutral-cure silicones include silicones that release alcohol or other volatile organic compounds (VOCs) as they cure. In addition, other silicone-based and / or siloxane-based additives (e.g., siloxane polymers) may be used, including, but not limited to, hydroxyl-terminated (or hydroxy) siloxanes and / or siloxanes terminated with other reactive groups, acrylic siloxanes, urethane siloxanes, epoxy siloxanes, and mixtures and derivatives thereof.As detailed 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 approximately 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.) ranges from approximately 20 cSt (25 °C) to approximately 2000 cSt (25 °C). In other forms, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is between approximately 100 cSt (25 °C) and approximately 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 between approximately 250 cSt (25 °C) and 1000 cSt (25 °C). In still other embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral-cure silicone, silanol fluid, siloxane polymers, etc.) is between approximately 400 cSt (25 °C) and 800 cSt (25 °C). And in particular embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral-cure silicone, silanol fluid, siloxane polymers, etc.) is between approximately 800 cSt (25 °C) and approximately 1250 cSt (25 °C). In addition, one or more silicone-based additives with higher and / or lower viscosities can be used.For example, in additional modes, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral-cure silicone, silanol fluid, siloxane polymers, etc.) is between approximately 20 cSt (25 °C) and approximately 200,000 cSt (25 °C), between approximately 1,000 cSt (25 °C) and approximately 100,000 cSt (25 °C), or between approximately 80,000 cSt (25 °C) and approximately 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 between approximately 1000 cSt (25 °C) and approximately 20,000 cSt (25 °C), between approximately 1000 cSt (25 °C) and approximately 10,000 cSt (25 °C), between approximately 1000 cSt (25 °C) and approximately 2000 cSt (25 °C), or between approximately 10,000 cSt (25 °C) and approximately 20,000 cSt (25 °C).In still other forms, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymers, etc.) is between approximately 1000 cSt (25 °C) and approximately 80,000 cSt (25 °C), between approximately 50,000 cSt (25 °C) and approximately 100,000 cSt (25 °C), or between approximately 80,000 cSt (25 °C) and approximately 200,000 cSt (25 °C). In still other configurations, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral-cure silicone, silanol fluid, siloxane polymers, etc.) ranges from approximately 20 cSt (25°C) to approximately 100 cSt (25°C). Other viscosities may also be used as desired. In a preferred embodiment, the magnesium cement composition, particularly the magnesium oxychloride cement composition, comprises a single 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 include a mixture of one or more silicone oils and neutral-cure silicones. In particular embodiments, the ratio of silicone oil to neutral-cure silicone may be between approximately 1:5 and approximately 5:1 by weight. In other embodiments, the ratio of silicone oil to neutral-cure silicone may be between approximately 1:4 and approximately 4:1 by weight. In still other embodiments, the ratio of silicone oil to neutral-cure silicone may be between approximately 1:3 and approximately 3:1 by weight.In still other configurations, the ratio of silicone oil to neutral-cure silicone can be between approximately 1:2 and approximately 2:1 by weight. In additional configurations, the ratio of silicone oil to neutral-cure silicone can be approximately 1:1 by weight. It is conceivable that one or more crosslinking agents may be used in magnesium cement. In some embodiments, the crosslinking agents are silicone-based. Illustrative crosslinking agents include, but are not limited to, methylrimethoxysilane, methyltriethoxysilane, methyltris(methylethylkethoximino)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 may be between approximately 1:20 and approximately 20:1 by weight, between approximately 1:10 and approximately 10:1 by weight, or between approximately 1:1 and approximately 10:1 by weight. Magnesium (oxychloride) cement compositions comprising one or more silicone-based additives may exhibit reduced water sensitivity compared to traditional magnesium (oxychloride) cement compositions. Furthermore, in some embodiments, magnesium (oxychloride) cement compositions comprising one or more silicone-based additives may exhibit little or no water sensitivity. Magnesium (oxychloride) cement compositions comprising one or more silicone-based additives may also exhibit hydrophobic and water-resistant properties. qq l Lnn / rznz / E / γΐΛΐ Furthermore, magnesium (oxychloride) cement compositions comprising one or more silicone-based additives can exhibit improved curing characteristics. For example, magnesium (oxychloride) cement compositions cure to form various reaction products, including the 3Mg(OH)₂.MgCl₂.8H₂O (phase 3) and 5Mg(OH)₂.MgC₁₂.8H₂O (phase 5) crystal structures. In some situations, higher percentages of the 5Mg(OH)₂.MgC₁₂.8H₂O (phase 5) crystal structure are preferred. In such situations, the addition of one or more silicone-based additives to magnesium oxychloride cement compositions can stabilize the curing process, which can increase the percentage yield of the 5Mg(OH)₂.MgC₁₂.8H₂O (phase 5) crystal structures.For example, in some embodiments, magnesium oxychloride compositions comprising one or more silicone-based additives can cure to form more than 80% of the 5Mg(OH)2.MgCl2.8H2O (phase 5) crystal structures. In other embodiments, magnesium oxychloride compositions comprising one or more silicone-based additives can cure to form more than 85% of the 5Mg(OH)2.MgCl2.8H2O (phase 5) crystal structures. In still other embodiments, magnesium oxychloride compositions comprising one or more silicone-based additives can cure to form more than 90% of the 5Mg(OH)2.MgCl2.8H2O (phase 5) crystal structures. In still other forms, magnesium oxychloride compositions comprising one or more silicone-based additives can cure to form more than 95% of the 5Mg(OH)2.MgC12.8H2O (phase 5) crystalline structures.In still other embodiments, magnesium oxychloride compositions comprising one or more silicone-based additives can cure to form more than 98% of the 5Mg(OH)₂.MgCl₂.8H₂O (phase 5) crystalline structures. In still other embodiments, magnesium oxychloride compositions comprising one or more silicone-based additives can cure to form approximately 100% of the 5Mg(OH)₂.MgCl₂.8H₂O (phase 5) crystalline structures. Furthermore, magnesium (oxychloride) cement compositions comprising one or more silicone-based additives can also exhibit enhanced strength and bonding characteristics. If desired, magnesium (oxychloride) cement compositions comprising one or more silicone-based additives can also be used to manufacture relatively thin concrete or magnesium (oxychloride) cement structures.For example, magnesium cement (oxychloride) compositions comprising one or more silicone-based additives can be used to manufacture cement or concrete structures or layers that are less than 8 mm thick, preferably less than 6 mm. To achieve coupling between the coupling parts, a temporary deformation of the coupling part(s) may be desired and / or even required. As a result, it is beneficial to mix magnesium oxide and / or magnesium hydroxide and / or magnesium chloride and / or magnesium sulfate with one or more silicone-based additives, as this leads to an increase in the degree of flexibility and / or elasticity. For example, in some embodiments, cement and concrete structures formed using magnesium oxychloride cement compositions can be bent or flexed without cracking or breaking. Magnesium (oxychloride) cement compositions comprising one or more silicone-based additives may further comprise one or more additional additives. These additional additives may be used to enhance particular characteristics of the composition. For example, in some embodiments, the additional additives may be used to make structures formed using the described magnesium oxychloride cement compositions resemble stone (e.g., granite, marble, sandstone, etc.). In certain embodiments, the additional additives may include one or more pigments or colorants. In other embodiments, the additional additives may include fibers, including, but not limited to, paper fibers, wood fibers, polymer fibers, organic fibers, and glass fiber.Magnesium oxychloride cement compositions can also form UV-stable structures, so that the color and / or appearance are not subject to substantial UV light loss over time. In addition, other additives may be included in the composition, including, but not limited to, plasticizers (e.g., polycarboxylic acid plasticizers, polycarboxylate ether-based plasticizers, etc.), surfactants, water, and mixtures and combinations thereof. As stated above, the composition of magnesium oxychloride cement, if used, may comprise magnesium oxide (MgO), aqueous magnesium chloride (MgCh(aq)), and one or more silicone-based additives. Magnesium chloride powder (MgCh) may also be used instead of aqueous magnesium chloride (MgCh).For example, magnesium chloride powder (MgCh) can be used in combination with an amount of water that would be equivalent or otherwise analogous to the addition of aqueous magnesium chloride (MgCh (aq)). In certain formulations, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride (MgCh(aq)) may vary, if applicable, in the composition of the magnesium oxychloride cement. In some formulations, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride (MgCh(aq)) is between approximately 0.3:1 and approximately 1.2:1 by weight. In other formulations, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride (MgCh(aq)) is between approximately 0.4:1 and approximately 1.2:1 by weight. And in still other formulations, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride (MgCh(aq)) is between approximately 0.5:1 and approximately 1.2:1 by weight. Aqueous magnesium chloride (MgCE(aq)) can be described as (or otherwise derived from) a magnesium chloride brine solution. Aqueous magnesium chloride (MgCb(aq)) (or magnesium chloride brine) may further 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 silicone-based additives (liquids) within the magnesium oxychloride cement composition can be defined as the 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 between 0.06 and 0.6. Preferably, it is also conceivable, and even desirable, to incorporate at least one oil, such as linseed oil or silicone oil, into the core layer. This makes the magnesium-based core layer and / or the thermoplastic-based core layer more flexible and reduces the risk of cracking. Instead of or in addition to oil, it is also conceivable to incorporate one or more water-soluble polymers or polycondensed (synthetic) resins, such as polycarboxylic acid, into the core layer.This leads to the advantage that during drying / curing / setting the panel will not shrink, which prevents the formation of cracks, and also gives the core layer, after drying / curing / setting, a more hydrophobic character, which prevents the penetration of water (moisture) during storage and subsequent use. It is conceivable that the core layer comprises polycaprolactone (PCL). This biodegradable polymer is particularly preferred since it has been found to melt by the exothermic reaction of the reaction mixture. It has a melting point of approximately 60 °C. PCL can be either low-density or high-density. The latter is particularly preferred as it produces a stronger core layer. Instead of, or in addition to, other polymers may be used, preferably a polymer selected from the group consisting of: another poly(lactic-co-glycolic acid) (PLGA), poly(lactic acid) (PLA), poly(glycolic acid) (PGA), the polyhydroxyalkanoate (PHA) family, polyethylene glycol (PEG), polypropylene glycol (PPG), polyesteramide (PEA), poly(lactic acid-cocaprolactone), poly(lactide-co-trimethylenecarbonate), poly(sebacic acid-co-ricinoleic acid), and a combination thereof. Alternatively, the panel, particularly the core layer, may be made at least partially of PVC, PET, PP, PS, or polyurethane (thermoplastic) (PUR). The PS may be in the form of expanded polystyrene (EPS) to further reduce the panel's density, leading to cost savings and easier handling. Preferably, at least a fraction of the polymer used may be made from recycled thermoplastic, such as recycled PVC or recycled PUR. The recycled PUR may be manufactured from recyclable polymers, such as recycled PET. The PET may be chemically recycled using glycolysis or depolymerization of PET into monomers or oligomers and subsequently into polyurethane polyols. It is also conceivable that the rubber and / or elastomeric parts (particles) are dispersed within at least one composite layer to improve flexibility and / or impact resistance, at least to some extent.It is conceivable that a mixture of virgin and recycled thermoplastic material may be used to compose at least part of the core. Preferably, in this mixture, the virgin and recycled thermoplastic materials are essentially the same. For example, such a mixture may be entirely PVC-based or entirely PUR-based. The core may be solid or foamed, or both if it is composed of multiple parts / layers. It may be advantageous if the core layer comprises porous granules, particularly porous ceramic granules. Preferably, the granules have a plurality of micropores with an average diameter of 1 to 10 micrometers, preferably 4 to 5 micrometers. That is, the individual granules preferably have micropores. Preferably, the micropores are interconnected. Preferably, they are not confined to the surface of the granules but are substantially distributed throughout the cross-section of the granules. Preferably, the granule size is from 200 to 900 micrometers, preferably from 250 to 850 micrometers, especially from 250 to 500 micrometers or from 500 to 850 micrometers. Preferably, at least two different granule sizes are used, with two being the most preferred. Preferably, small and / or large granules are used.The small granules may have a size range of 250 to 500 micrometers. Preferably, the large granules have a diameter of 500 to 850 micrometers. Each granule may be substantially the same size or of two or more predetermined sizes. Alternatively, two or more distinct size ranges may be used, with a variety of different-sized particles within each range. Preferably, two different sizes or size ranges are used. Preferably, each granule comprises a plurality of microparticles, each microparticle being substantially partially fused with one or more adjacent microparticles to define a network that defines the micropores. Each microparticle preferably has an average size of 1 to 10 micrometers, with an average of 4 to 5 micrometers.Preferably, the average size of the micropores is 2 to 8 micrometers, with a maximum preference of 4 to 6 micrometers. The micropores may be irregularly shaped. Consequently, the size of the micropores, and indeed the midipores referred to below, is determined by adding the widest pore diameter to the narrowest pore diameter and dividing by 2. Preferably, the ceramic material is distributed uniformly throughout the cross-section of the core layer, i.e., substantially without the formation of clumps of ceramic material. Preferably, the microparticles have an average size of at least 2 micrometers or 4 micrometers and / or less than 10 micrometers or less than 6 micrometers, with a maximum preference of 5 to 6 micrometers. This particle size range has been found to allow for controlled micropore formation. The granules may further comprise a plurality of substantially spherical midipores having an average diameter of 10 to 100 microns. These substantially increase the overall porosity of the ceramic material without compromising its mechanical strength. The midipores are preferably interconnected through a plurality of micropores. That is, the midipores may be in fluid connection with each other through micropores. The average porosity of the ceramic material itself is preferably at least 50%, more preferably over 60%, with the highest preference being 70 to 75% average porosity. The ceramic material used to produce the granules may be any (non-toxic) ceramic known in the art, such as calcium phosphate and glass ceramics. The ceramic may be a silicate, although preferably it is a calcium phosphate, especially tricalcium phosphate [alpha] or [beta], or hydroxyapatite, or mixtures thereof.Most preferably, the mixture is hydroxyapatite and tricalcium phosphate [beta], especially more than 50% tricalcium phosphate [beta] w / w, with the highest preference being 85% tricalcium phosphate [beta] and 15% hydroxyapatite. Most preferably, the material is 100% hydroxyapatite. Preferably, the cement composition or dry premix comprises 15 to 30% by weight of granules of the total dry weight of the composition or premix. Porous particles can lead to a lower average core layer density and, therefore, a weight reduction that is advantageous from both an economic and handling perspective. Furthermore, the presence of porous particles in the core layer typically leads, at least to some extent, to increased porosity on both the upper and lower surfaces of the core layer. This is beneficial for bonding an additional layer to the upper and / or lower surfaces of the core layer, such as a primer, an adhesive (initially liquid), or another decorative or functional layer. Often, these layers are initially applied in a liquid state, where the pores allow the liquid substance to be absorbed (permeate), increasing the surface area of ​​contact between the layers and thus improving the bond strength. The panels may comprise a layered structure, comprising, for example, a central core (or core layer) and at least one decorative top section, fixed directly or indirectly to, or integrated with, said core layer, wherein the top section defines a top surface of the panel. The top section preferably comprises at least one decorative layer fixed either directly or indirectly to a top surface of the core layer. The decorative layer may be a printed layer, such as a printed PVC layer, a printed PU layer, or a printed paper layer, and / or may be coated by at least one protective (top) layer that covers said decorative layer. The protective layer further forms part of the decorative top section.The presence of a print layer and / or a protective layer may prevent the tile from being damaged by scratches and / or environmental factors such as UV radiation, humidity, and / or wear and tear. The print layer may consist of a film onto which a decorative print is applied, wherein the film is affixed to the substrate layer and / or an intermediate layer, such as a primer layer, situated between the substrate layer and the decorative layer. The print layer may also consist of at least one ink layer applied directly to the top surface of the core layer, or onto a primer layer applied to the substrate layer. The panel may comprise at least one wear layer affixed, either directly or indirectly, to a top surface of the decorative layer. The wear layer also forms part of the decorative top section.Each panel may comprise at least one lacquer layer fixed, either directly or indirectly, to an upper surface of the decorative layer, preferably to an upper surface of the wear layer. The underside (rear side) of the core (layer(s)) may also constitute the underside (rear side) of the panel itself. However, it is conceivable, and may even be preferable, for the panel to comprise a support layer, directly or indirectly, attached to the underside of the core. Typically, the support layer acts as a balancing layer to stabilize the shape, particularly the flatness, of the panel. In addition, the support layer typically contributes to the sound-damping properties of the panel. Since the support layer is typically a closed layer, applying the support layer to the underside of the core will cover the core slots, at least partially and preferably completely. Here, the length of each core slot is preferably less than the length of the support layer.The support layer may be provided from cut portions, wherein at least some of said cut portions overlap with at least one core groove. The at least one support layer is preferably made at least partially of a flexible material, preferably an elastomer. The thickness of the support layer typically ranges from approximately 0.1 to 2.5 mm. Non-limiting examples of materials from which the support layer may be at least partially composed are polyethylene, cork, polyurethane, polyvinyl chloride, and ethylene-vinyl acetate. Optionally, the support layer comprises one or more additives, such as fillers (like chalk), colorants, resins, and / or one or more plasticizers. In one particular embodiment, the support layer is made at least partially from a composite of crushed (or scraped) cork particles bonded by resin.Instead of cork, other tree-based products, such as wood, can be used. The thickness of a polyethylene backing layer is typically 2 mm or less. The backing layer can be solid or foamed. A foamed backing layer can further enhance the sound-dampening properties. A solid backing layer can improve the desired balance and stability of the panel. The interior of the up-facing tongue and the interior of the down-facing tongue can be in contact in a coupled state to transfer forces between them, particularly from the up-facing tongue to the down-facing tongue. The interiors of the tongues can be in contact at the tongue contact surfaces, where the tongue contact surfaces can be inclined. The inclination can be such that at least a portion of the interior of the up-facing tongue is tilted sideways, so that a tangent line from the tongue contact surface intersects the interior vertical plane above the tongue contact surface.Alternatively, the angle can be such that at least a portion of the inside of the tongue is angled away from the side and upward, so that a tangent line from the tongue's contact surface intersects the interior vertical plane below the tongue's contact surface. These are closed-slot and open-slot systems, respectively. Closed-slot systems provide improved engagement but are more difficult to attach, while open-slot systems are easier to attach but do not provide the additional vertical engagement of a closed-slot system. The first and second coupling parts are arranged on opposite sides of the panel. The panel is, for example, rectangular or parallelogram-shaped and / or elongated, and the first and second coupling parts can be arranged on both opposite sides (i.e., on all four sides) of the panel. Furthermore, it is possible to provide the first and second coupling parts only on one pair of opposite sides, and provide other coupling parts, such as downward-sloping coupling parts with a side tab and a side groove, on the other pair of opposite sides. The invention further relates to a covering, in particular a floor covering, comprising multiple interconnected panels according to any of the present invention. The invention will be clarified on the basis of non-limiting illustrative embodiments shown in the following figures. The relevant elements are indicated in the figures by corresponding reference numbers. In the Figures: - Figure 1 schematically shows two interconnected panels with the first and second coupling parts according to the present invention; - Figure 2 schematically shows a first coupling part of a panel according to the present invention and Figure 1; - Figure 3 schematically shows a second coupling part of a panel according to the present invention and Figure 1; - Figure 4 schematically shows a modality of two interconnected panels with the first and second coupling parts according to the present invention; - Figure 5 schematically shows a detailed view of part A of the modality shown in Figure 4; and - Figure 6 schematically shows a detailed view of part B of the modality shown in Figure 4. Figure 1 shows a floor panel (1), comprising a first coupling part (2) and a second coupling part (3) in the coupled state. The first coupling part (2) comprises an upward tongue (4), an upward side (5) located at a distance from the upward tongue (4), and an upward groove (6) formed between the upward tongue (4) and the upward side (5), wherein the upward groove (6) accommodates the downward tongue (7) of a second coupling part (3) of another panel (1). The side of the upward tongue (4) facing the upward side is the inner (8) of the upward tongue (4), and the side of the upward tongue (4) opposite the upward side (5) is the outer (9) of the upward tongue (4). The second coupling part (3) comprises a downward tongue (7), a downward side (10) located at a distance from the downward tongue (7), and a downward groove (11) formed between the downward tongue (7) and the downward side (10). The side of the downward tongue (7) facing the downward side (10) is the inner (12) of the downward tongue (7), and the side of the downward tongue (7) opposite the downward side (10) is the outer (13) of the downward tongue (7). The outer edge (13) of the downward-facing tab (7) and the upward-facing side (5) both comprise an upper contact surface (14) on the top of the panel (1), the upper contact surfaces (14) of which are in contact and extend vertically. Adjacent to the upper contact surfaces (14), both the downward-facing tab (7) and the upward-facing side (5) comprise an inclined contact surface (15), the inclined contact surfaces (15) of which are in contact, wherein the upper contact surfaces (14) on the one hand, and the inclined contact surfaces (15) of the upward-facing side (5) and / or the outer edge (13) of the downward-facing tab (7) on the other hand, preferably mutually enclose an angle (a) of approximately 125 degrees.The upper contact surface (14) and the inclined contact surface (15) of the upward side (5) mutually enclose a first angle of approximately 125 degrees, and the upper contact surface (14) and the inclined contact surface (15) of the downward tongue (7) mutually enclose a second angle of approximately 125 degrees. Adjacent to the inclined contact surface (15), the downward-facing tongue (7) comprises an outer surface (16), and adjacent to the inclined contact surface (15), the upward-facing side (5) comprises an inner surface (17), wherein the inner (17) and outer (16) surfaces are parallel and vertical. A space (18) is present between the outer surface (16) and the inner surface (17). The upper contact surfaces (14) define an inner vertical plane (19), wherein the inclined contact surface (15) of the downward-facing tongue (7) extends beyond the inner vertical plane (19), and the inclined contact surface (15) of the upward-facing side (5) is located inward relative to the inner vertical plane (19). A portion (20) of the downward-facing tongue (7) extends beyond the inner vertical plane (19), wherein said portion (20) is substantially trapezoidal or wedge-shaped. The inclined contact surfaces (15) are arranged entirely outside and contiguous to the inner vertical plane (19). The portion (20) is elongated with a larger vertical portion relative to the horizontal portion. The lower part (21) of the downward-facing tongue (7) makes contact with the upper side (22) of the upward-facing groove (6) on a contact surface of the groove (23), wherein there is a space (24) between the first (2) and second (3) mating parts, which extend from the inclined contact surfaces (15) to the contact surface of the groove (23). qq l Lnn / rznz / E / γΐΛΐ Additionally, the upper surface (25) of the upward-facing tongue (4) and the upper surface (26) of the downward-facing groove (11) are spaced apart from each other so that there is a space (27) between the two surfaces (25, 26). The exterior (9) of the upward-facing tongue (4) comprises a first engagement element (28), in the form of an outward-facing protrusion, and the downward-facing side (10) is provided with a second engagement element (29), in the form of a cavity, wherein the first (28) and at least a part of the second (29) engagement element are in contact, and form a surface of the engagement element (30). Figures 2 and 3 show the first and second coupling parts individually. The outward-facing protrusion (28) comprises an upper portion (31) and an adjacent lower portion (32), wherein the lower portion (32) comprises an inclined engagement surface (30a) and the upper portion (31) comprises a curved guide surface (32'). The cavity (29) comprises an upper portion (33) and an adjacent lower portion (34), wherein the lower portion comprises an inclined engagement surface (30B). The upper portion (31, 33) extends over a larger vertical section compared to the lower portion (32, 34). The parts of the first (28) and second (29) coupling element that are in contact are the inclined coupling surfaces (30, 30A, 30B) of the coupling elements (28, 29) and the upper portions (31, 33) of the first (28) and second (29) coupling elements are at least partially separated. The exterior (9) of the upward-facing tab (7) comprises an upper outer portion (35) and a lower outer portion (36), wherein the first locking element (28) is disposed between the lower outer portion (36) and the upper outer portion (35). The lower outer portion (36) is disposed closer to the interior (8) of the upward-facing tab (4) compared to the upper outer portion (35). The upper outer portion (35) is substantially vertical and defines an outer vertical plane (37), in which the first engagement element (28) projects from the outer vertical plane (37). The lower outer portion (36) is substantially vertical, and the inclined engagement surface (30A) or the lower portion (32) and the lower outer portion (36) enclose an angle (β) between 100 and 175 degrees. The angle (α) enclosed by the upper contact surfaces and the inclined contact surfaces and the angle (β) enclosed by the lower outer portion (36) and the inclined engagement surface (30A) or the lower portion (32) are approximately the same. An outer portion (38) of the first engagement element (28) is arranged on a horizontal level that is lower compared to the upward-facing slot (6). qq l Lnn / eznz / E / YiAi Figure 4 schematically shows an embodiment of two interconnected panels (1) with first and second coupling parts according to the present invention. The panels (1) comprise a first coupling part (2) and a second coupling part (3) in the coupled state. The embodiment shown includes all the features shown in Figure 1 and further includes a cavity (40) positioned below the upper contact surface (14a) of the second coupling part (3). The cavity (40) comprises an inclined upper surface and an inclined lower surface. The inclined lower surface aligns with the inclined contact surface (15a) of the downward-facing tab (7).The cavity (40) can act as an expansion chamber to allow the panel material to swell, for example, when exposed to heat and / or humidity and, furthermore, reduces the surface contact area at the top seam between two panels (1), allowing clamping forces to be more prominently present at the top seam between said panels (1) to enhance the water barrier properties of the panel coupling as such. Figure 5 schematically shows a detailed view of Part A of the configuration shown in Figure 4 around the upper contact surfaces of two interconnected panels. The figure shows two contact points or zones (41, 42) where the coupling force (or clamping force) in this specific area of ​​the coupling parts (2, 3) is higher than in other parts shown in these figures. These two points or zones of intensive contact (41, 42) lead to a significantly improved water barrier and, therefore, an improved watertight connection between the panels (1). The figure shows that the upper contact areas 14b and 14a are not completely parallel; rather, the upper contact area 14b is slightly inclined with respect to the opposite vertical upper contact area 14a, and more specifically, it runs slightly in the opposite direction to the vertical upper contact area 14a in the downward direction.This does not necessarily mean that the upper contact areas 14a, 14b will separate from each other in a downward direction, but it commonly leads to the effect that the contact between the upper portions of the upper contact areas 14a, 14b is more intense than the contact between the lower portions of the upper contact areas 14a, 14b. It is conceivable that, due to the engagement force, the area on or around the downward-facing inclined contact surface 15a of the tongue may deform elastically or plastically during the engagement of the adjacent inclined contact surfaces. Locally, the area on or around the inclined contact surface 15b may also deform elastically or plastically. qq l Lnn / rznz / E / γΐΛΐ Figure 6 schematically shows a detailed view of part B of the mode shown in Figure 4 and around the attachment elements (28, 29) of two interconnected panels. The upper outer portion (35) is substantially vertical and defines an outer vertical plane (37), in which the first engagement element (28) projects from the outer vertical plane (37). The distance (39a) between an outermost portion (38) of the first engagement element (28) and the outer vertical plane (37) is substantially half the distance (39b) between an outermost portion of the second engagement element (29) and the vertical plane (37). Distance 39b is preferably less than 0.75 mm and distance 39a is preferably less than 0.375 mm. In one embodiment, the horizontal distance between the outer vertical plane (37) and the upper contact surface is a distance D. Distance 39b can be approximately 0.4 times that distance D and distance 39a can be approximately 0.2 times that distance D. The ordinal numbers used in this document, such as “first,” “second,” and “third,” etc., are used for identification purposes only. The panels according to the invention may also be referred to as tiles. The core (layer) of the panel may also be referred to as the base (layer) and may consist of a plurality of sublayers, which may include, for example, a reinforcing layer, such as a fiberglass layer. The mating parts may also be referred to as mating profiles or connecting profiles. Complementary mating profiles are understood to be those that can cooperate with each other. However, for this purpose, the complementary mating profiles need not necessarily have complementary shapes. Interlocking in the vertical direction is understood to mean interlocking in a direction perpendicular to the plane of the panel.Horizontal engagement means engagement in a direction perpendicular to the respective mating edges of two panels and parallel or downward along the plane defined by the panels. In the context of this document, the terms “foamed composite” and “foamed plastic material” (or “foamed plastic material”) are interchangeable, wherein the foamed composite comprises a foamed mixture comprising at least one (thermo)plastic material and at least one filler (non-polymeric material). The inventive concepts described above are illustrated by various illustrative methods. It is conceivable that individual inventive concepts can be applied without also applying other details of the described example. It is not necessary to provide examples of all conceivable combinations of the inventive concepts described above, since a person skilled in the art will understand that numerous inventive concepts can be (re)combined to arrive at a specific application. It is understood that the verb “comprender” and its conjugations used in this patent publication mean not only “comprender”, but also the phrases “contener”, “consiste substantially en”, “formnado por” and their conjugations.

Claims

1. The panel (1), in particular a floor panel, comprising: a. at least a first coupling part (2) and at least a second coupling part (3) arranged on opposite sides of the panel (1), wherein the first coupling part (2) of said panel and the second coupling part (3) of another panel (1) are arranged to couple with a downward movement; b.wherein the first coupling part (2) comprises an upward-facing tongue (4), at least one upward-facing side (5) located at a distance from the upward-facing tongue (4), and an upward-facing groove (6) formed between the upward-facing tongue (4) and the upward-facing side (5), wherein the upward-facing groove (6) is adapted to receive at least a portion of a downward-facing tongue (7) of a second coupling part (3) of another panel (1), wherein the side of the upward-facing tongue (4) that faces the upward-facing side is the inside (8) of the upward-facing tongue (4), and the side of the upward-facing tongue (4) opposite the upward-facing side (5) is the outside (9) of the upward-facing tongue (4), wherein at least a portion of the inside (8) of the upward-facing tongue (4) is inclined toward the upward-facing side (5); c.wherein the second coupling part (3) comprises a downward tongue (7), at least one downward side (10) located at a distance from the downward tongue (7), and a downward groove (11) formed between the downward tongue (7) and the downward side (10), wherein the downward groove (11) is adapted to receive at least a portion of an upward tongue (4) of a first coupling part (2) of another panel (1), wherein the side of the downward tongue (7) facing the downward side (10) is the inside (12) of the downward tongue (7) and the side of the downward tongue (7) opposite the downward side (10) is the outside (13) of the downward tongue (7), wherein at least a portion of the inside (12) of the downward tongue (7) is inclined towards the downward side (10); d.wherein the exterior (13) of the downward-facing tab (7) and the upward-facing side (5) both comprise an upper contact surface (14) near or towards the top of the panel (1), wherein at least one of said contact surfaces (14) preferably extends vertically at least partially, and wherein the upper contact surface (14) of the exterior (13) of the downward-facing tab (7) of said panel is configured to engage with the upper contact surface (14) of the upward-facing side (5) of an adjacent panel, in the engaged state of said panels (1); e.wherein the exterior (9) of the upward-facing tongue (4) comprises a first locking element (28) comprising an outward-facing protrusion and wherein the downward-facing side (10) is provided with a second locking element (29) comprising a cavity, wherein, in the coupled state of the adjacent panels, at least a portion of the first locking element (28) of said panel and at least a portion of the second locking element (29) of another panel are in contact to effect a locking effect, preferably a vertical locking effect of the panels (1) with respect to each other; f.characterized in that the exterior of the outward protrusion (28) comprises an upper portion (31) and an adjacent lower portion (32), wherein the lower portion (32) comprises a flat inclined engagement surface (30a) and the upper portion (31) comprises a curved guide surface (32'), wherein said inclined engagement surface (30a) forms a fold with the curved upper portion (31, 32); g. in that the cavity (29) comprises a curved upper portion (33) and an adjacent lower portion (34), wherein the lower portion comprises a flat inclined engagement surface (30b) wherein said inclined engagement surface (30b) forms a fold with the curved upper portion (31, 32); h.and because, in the coupled state of the adjacent panels, the inclined engagement surface (30a) of the lower portion (32) of the outward protrusion (28) and the inclined engagement surface (30b) of the lower portion (34) of the cavity (29) are in contact to effect said engagement effect between the panels and wherein, in the coupled state of the adjacent panels (1), the upper portions (31, 33) of the first engagement element (28) and the second engagement element (29) are at least partially separated.

2. The panel (1) according to claim 1, wherein the entire interior (8) of the upward-facing tab (4) is inclined sideways upwards (5), and wherein the entire interior (12) of the downward-facing tab (7) is inclined sideways downwards (10). qq l Lnn / rznz / E / γΐΛΐ 3. The panel (1) according to claim 1 or 2, wherein, in the coupled state of the adjacent panels, the upper portions (31, 33) of the first locking element (28) and the second locking element (29) are completely separated.

4. The panel (1) according to any of the preceding claims, wherein, in the coupled state of the adjacent panels, only a portion of the inclined engagement surface (30a) of the lower portion (32) of the outward protrusion (28) acts in conjunction with only a portion of the inclined engagement surface (30b) of the lower portion (34) of the cavity (29).

5. The panel (1) according to any of the preceding claims, wherein at least an upper portion (31) of the outward protrusion (28) is positioned at a higher level than a level defined by the lowest point of the upward groove (6), and wherein at least a portion of the upper portion (33) of the cavity (29) is positioned at a higher level than a level defined by the lowest point of the upward groove (6).

6. The panel (1) according to any of the preceding claims, wherein the length of the inclined engagement surface (30a) of the lower portion (32) of the outward protrusion (28) is greater, preferably at least 1.5 times greater, than the inclined engagement surface (30B) of the lower portion (34) of the cavity (29).

7. The panel (1) according to any of the preceding claims, wherein the upper portion (31, 33) extends over a larger vertical section compared to the lower portion (32, 34), wherein, preferably, the height of the upper portion (31, 33) is at least three times the height of the lower portion (32, 34).

8. The panel (1) according to any of the preceding claims, wherein the exterior (9) of the upward-facing tab (7) comprises an upper outer portion (35) and a lower outer portion (36), wherein the first locking element (28) is disposed between the lower outer portion (36) and the upper outer portion (35), wherein the lower outer portion (36) is disposed closer to the interior (8) of the upward-facing tab (4) compared to the upper outer portion (35).

9. The panel (1) according to claim 8, wherein the upper outer portion (35) is preferably substantially vertical and defines an outer vertical plane (37), wherein the first fastening element (28) projects from the outer vertical plane (37) at least partially, preferably by a maximum of 2 mm in the horizontal direction.

10. The panel (1) according to any of the preceding claims, wherein an outermost portion (38) of the first locking element (28) is arranged at a horizontal level that is lower compared to the upward-facing slot (6).

11. The panel (1) according to any of the preceding claims, wherein the upper contact surface (14) of the downward tab (7) extends vertically, and wherein the upper contact surface (14) of the upward side (5) is inclined downwards in a direction opposite to the upward tab (4), wherein, preferably, the vertical upper contact surface (14) of the downward tab (7) and the inclined upper contact surface (14) of the upward side (5) mutually enclose an angle of between 0 and 2 degrees, preferably between 0 and 1 degrees, more preferably between 0 and 0.5 degrees.

12. The panel (1) according to any of the preceding claims, wherein adjacent to the upper contact surfaces (14) both the downward tab (7) and the upward side (5) comprise an inclined contact surface (15), wherein the inclined contact surface (15) of the downward tab (7) of said panel is configured to engage with the inclined contact surface (15) of the upward side (5) of an adjacent panel, in the engaged state of said panels (1), wherein each vertical portion of the upper contact surface (14) and each adjacent inclined surface (15) mutually enclose an angle (a) between 100 and 175 degrees.

13. The panel (1) according to claim 12, wherein the inclined contact surface (15) of the downward-facing tab (7) extends a maximum of 1 mm, preferably a maximum of 0.5 mm, more preferably a maximum of 0.2 mm, in the horizontal direction with respect to an inner vertical plane (19) defined by the upper contact surfaces (14) of two panels in the coupled state.

14. The panel (1) according to claim 12 or 13, wherein the level of the inclined contact surfaces (15A, 15B) of the downward tab (7) and the upward side (5) is above the level of the highest point of the upward tab (4).

15. The panel (1) according to any one of claims 12-14, wherein the downward-inclined contact surface (15) of the tab defines at least a portion of the third engagement element, and wherein the upward-inclined contact surface (15) of the side (5) defines at least a portion of the fourth engagement element.

16. The panel (1) according to any one of claims 12-15, wherein adjacent to the inclined contact surface (15), the downward tab (7) comprises an outer surface (16), located below the inclined contact surface (15) of the downward tab (7), and wherein adjacent to the inclined contact surface (15), the upward side (5) comprises an inner surface (17), located below the inclined contact surface (15) of the upward side (5), wherein the inner (17) and outer (16) surfaces are substantially parallel and, preferably, extend at least partially in a vertical direction and / or curve at least partially.

17. The panel (1) according to any one of claims 12-16, wherein, in the coupled state of the adjacent panels, the upper contact surfaces (14) define an inner vertical plane (19), wherein the inclined contact surfaces (15a, 15b) are positioned on the same side of said inner vertical plane (19).

18. The panel (1) according to any one of claims 12-17, wherein, in the coupled state of the adjacent panels, the upper contact surfaces (14) define an inner vertical plane (19), wherein the inclined contact surfaces (15a, 15b) are positioned on one and the same side of said inner vertical plane (19).

19. The panel (1) according to any one of claims 12-18, wherein the length of the inclined contact surface (15) of the upward side (5) exceeds the length of the inclined contact surface (15) of the downward tab (7), wherein preferably the length of the inclined contact surface (15) of the upward side (5) is at least twice the length of the inclined contact surface (15) of the downward tab (7).

20. The panel (1) according to any one of claims 12-19, wherein, in the coupled state of the adjacent panels, the upper contact surfaces (14) define an inner vertical plane (19), wherein a portion (20) of the downward tongue (7), including its inclined contact surface (15a), extends beyond the inner vertical plane (19), wherein said portion (20) is substantially trapezoidal or wedge-shaped.

21. The panel (1) according to claim 20, wherein the height of said portion (20) exceeds the width of said portion, wherein, preferably, the maximum height of said portion (20) is at least three times the maximum width of said portion (20).

22. The panel (1) according to claim 20 or 21, wherein the width of the space (18) is equal to or exceeds the width of said portion (20) of the downward tab (20).

23. The panel (1) according to any one of claims 20-22, wherein, in the coupled state of the adjacent panels, the upper contact surfaces (14) define an inner vertical plane (19), wherein the inclined contact surfaces (15) are contiguous to the inner vertical plane (19).

24. The panel (1) according to any of claims 20-23, wherein the angle (β) enclosed by the upper contact surfaces and the inclined contact surfaces and the angle (β) enclosed by the lower outer portion (36) and the inclined engagement surface (30A) or the lower portion (32) differs within 20 degrees and is preferably the same.

25. The panel (1) according to any of the preceding claims, wherein, in the coupled state of the adjacent panels, there is a space (18) between at least a portion of the outer surface (16) of said panel (1) and at least a portion of the inner surface (17) of an adjacent panel (1).

26. The panel (1) according to any of the preceding claims, wherein, in the coupled state of the adjacent panels, a lower portion (21) of the downward-facing tongue (7) makes contact with the upper side (22) of the upward-facing groove (6) on a contact surface of the groove (23), and wherein a space (24) is present between the first (2) and second (3) coupling portions, extending from the inclined contact surfaces (15) to the contact surface of the groove (23).

27. The panel (1) according to any of the preceding claims, wherein, in the coupled state of the adjacent panels, a lower portion (21) of the downward-facing tongue (7) makes contact with the upper side (22) of the upward-facing groove (6) on a groove contact surface (23) that is preferably substantially horizontal, and wherein spaces (24) are present between the first (2) and second (3) coupling portions on both sides of said groove contact surface (23).

28. The panel (1) according to any of the preceding claims, wherein an upper surface (25) of the upward-facing tongue (4) and an upper surface (26) of the downward-facing groove (11), in the coupled state, are at least partially separated from each other so that a space (27) is present between the two surfaces (25, 26).

29. The panel (1) according to any of the preceding claims, wherein the upper contact surface (14) and the inclined contact surface (15) of the upward side (5) mutually enclose a first angle, and the upper contact surface (14) and the inclined contact surface (15) of the downward tab (7) mutually enclose a second angle, wherein the first and second angles differ by more than 20 degrees.

30. The panel (1) according to any of the preceding claims, wherein the exterior of the downward-facing tongue (7) comprises, between the upper contact surface (14) and an inclined contact surface (15a) and / or third fastening element, at least one cavity, wherein, in the coupled state of the adjacent panels, said cavity is preferably positioned at a distance from the upper contact surface (14) of the upward-facing side (5).

31. The panel (1) according to any of the preceding claims, wherein the exterior (9) of the upward-facing tab (7) comprises an upper outer portion (35) defining an outer vertical plane (37) dividing the upward-facing tab (4) into an inner section directed towards the upward-facing side (6), and an outer section comprising the first locking element (28), wherein the maximum width of the inner section is at least 8 times, preferably at least 10 times, the maximum width of the outer section.

32. The panel (1) according to any of the preceding claims, wherein the panel comprises at least a third coupling part and at least a fourth coupling part arranged on another pair of opposite sides of the panel (1), wherein the third coupling part of said panel and the fourth coupling part of another panel (1) are preferably arranged to couple by means of a downward tilting motion.

33. The panel (1) according to claim 32, wherein the third coupling portion comprises: • a side tab extending in a direction substantially parallel to the upper side of the core, • at least a second downward side located a distance from the side tab, and • a second downward groove formed between the side tab and the second downward side, and wherein the fourth coupling portion comprises: • a third groove configured to accommodate at least a portion of the side tab of the third coupling profile of an adjacent panel, said third groove being defined by an upper flange and a lower flange, wherein said lower flange is provided with an upward-facing locking element, wherein the third coupling portion and the fourth coupling portion are configured such that two of the panels can be coupled together by means of a twisting motion, wherein,in the coupled state: at least a portion of the side tab of a first panel is inserted into the third groove of an adjacent second panel, and wherein at least a portion of the upward-facing locking element of said second panel is inserted into the downward-facing second groove of said first panel.

34. The panel (1) according to any of the preceding claims, wherein the panel (1) is a decorative panel, comprising: • at least one core layer, and • at least one decorative top section, fixed directly or indirectly to said core layer, wherein the top section defines a top surface of the panel, • a plurality of side edges defined at least partially by said core layer and / or by the top side section, the at least two opposite side edges of which are provided with the first coupling part and the second coupling part, respectively.

35. The Cladding, in particular for flooring, comprising multiple interconnected panels (1) according to any of the preceding claims.

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