Panels and Coverings

Abstract

The market for flooring for floor coverings has seen significant advancements in recent decades. Various methods for installing floor panels on a subfloor are known. The present invention relates to improved panels, such as floor panels, particularly decorative floor panels. The present invention also relates to coverings, particularly floor coverings, comprising a plurality of interconnected panels according to the present invention.

Description

[Technical Field]

[0001] The present invention relates to a panel, in particular a floor panel, and to a covering, in particular a floor covering, comprising a plurality of panels according to the invention. [Background technology]

[0002] The market for floor coverings has seen significant advances in recent decades. Various methods for installing floor panels on a subfloor are known. For example, it is known to attach floor panels to the subfloor by gluing or nailing. Disadvantages of this technique include its high complexity and the need to disassemble the floor panels for subsequent modifications. An alternative installation method involves loosely installing floor panels on the subfloor and then mating them with each other via tongue-and-groove connections, which are often also glued together at the tongue-and-groove joints. The resulting floor, also known as floating parquet flooring, has the advantages of ease of installation and the ability to move the complete floor surface, which is often convenient for accommodating potential expansion and contraction phenomena. Examples of known floor panels are described in WO 2019 / 138365, EP 3597836, WO 2019 / 137964 and WO 2017 / 115202. Summary of the Invention [Problem to be solved by the invention]

[0003] Flooring options and requirements have also evolved. While flooring was once made from wood or wood-derived products, the market has recently evolved to include plastic-based panels such as PVC panels and even mineral-based panels such as magnesium oxide-based panels. Each of these alternatives has its own advantages and disadvantages. One disadvantage is that it can be difficult to interlock the panels together and to lock them together to create a watertight connection.

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved connection between panels, in particular a waterproof connection. [Means for solving the problem]

[0005] To this end, the invention provides a panel, in particular a floor panel, comprising at least one first connection and at least one second connection arranged on opposite sides of the panel, the first and second connections being adapted to connect with the first and second connections of other panels, preferably by a downward movement; wherein the first connecting portion includes an upward tongue, at least one upward flank provided at a distance from the upward tongue, and an upward groove formed between the upward tongue and the upward flank, the upward groove being adapted to receive at least a part of a downward tongue of a second connecting portion of another panel, the side of the upward tongue facing the upward flank being an inner side of the upward tongue, and the side of the upward tongue facing away from the upward flank being an outer side of the upward tongue, the second connecting portion includes a downward tongue, at least one downward flank spaced a distance from the downward tongue, and a downward groove formed between the downward tongue and the downward flank, the downward groove being adapted to receive at least a part of the upward tongue of the first connecting portion of another panel, the side of the downward tongue facing the downward flank being an inner side of the downward tongue, and the side of the downward tongue facing away from the downward flank being an outer side of the downward tongue, the outer side of the downward tongue and the upward flank both comprise upper contact surfaces near, at, or adjacent to or at the top side of the panel, which upper contact surfaces are in contact in the connected state of the panels, and at least one of the upper contact surfaces preferably extends at least partially in a vertical direction; an outer side of the upwardly facing tongue includes a first locking element in the form of an outward bulge, and the downwardly facing flank includes a second locking element in the form of a recess, at least a portion of the first locking element and at least a portion of the second locking element contacting each other in a coupled state of the panels to form a locking element surface; the outwardly bulging outer portion includes an upper portion and an adjacent lower portion, the lower portion including an inclined locking surface, and the upper portion including a guide surface, preferably curved; the recess includes an upper portion and a lower portion adjacent thereto, the lower portion including an inclined locking surface, and a portion of the first locking element and a portion of the second locking element that contact each other in a coupled state of the panels are the inclined locking surfaces of the locking elements; When the panels are connected to each other, an upper portion of the first locking element and an upper portion of the second locking element are at least partially spaced apart.

[0006] In describing the present invention, terms such as top, bottom, upper, lower, horizontal, and vertical are used based on the flooring configuration, with the side facing upward being the top, or upper side, and the side in contact with the subfloor being the bottom, or lower side, with the panel being horizontally oriented, i.e., positioned on a horizontal surface. The panels of the present invention can also be used as wall coverings, but in that case they are typically installed vertically. In this case, the side facing the wall is the bottom and the side facing the room is the top, with the vertical and horizontal orientations interchanged. The wall panel itself can also be considered to be positioned on the floor, as if it were positioned as a floor panel. This also applies to ceiling coverings. The panels of the present invention can also be used as ceiling coverings, in which case the panel is installed on the ceiling, with the top and bottom orientations interchanged. The ceiling panel itself can also be considered to be positioned on the floor, as if it were positioned as a floor panel.

[0007] The joints of two panels interact to lock the panels together, typically horizontally and vertically, by placing an upward tongue in a downward groove and a downward tongue in an upward groove, in the direction of the face of the panel, i.e. horizontally in the case of floor coverings, for example.

[0008] Preferably, at least a portion, more preferably the entire inner side of the upward tongue is inclined towards the upward flank, and at least a portion, more preferably the entire inner side of the downward tongue is inclined towards the downward flank, which typically has the beneficial effect that the upward lower part is at least partially surrounded and fixed, and possibly clamped, by the downward groove, and that the downward tongue is at least partially surrounded and fixed, and possibly clamped, by the upward groove.

[0009] The panels are typically arranged to interlock with a downward motion. Such a motion is also referred to as a drop-down motion or vertical motion, which may mean that a new panel can be pushed into an already-placed panel. Such interlocking is also possible when panels are connected with a zipper-like or scissor-like motion. Alternatively, the panels may be arranged to interlock with an angular (downward) motion. Such a motion may also be referred to as a rotational motion, in which a portion of the new panel is inserted into a portion of the already-placed panel and then fully inserted with an angular motion. In a preferred embodiment, the panels include at least one third connector and at least one fourth connector, each disposed on a pair of opposing sides of the panels, and the third connector of one panel and the fourth connector of another panel are preferably arranged to interlock with an angular downward motion.

[0010] Preferably, the third connecting portion includes a lateral tongue extending in a direction substantially parallel to the upper side of the core, at least one second downward flank spaced a distance from the lateral tongue, and a second downward groove formed between the lateral tongue and the second downward flank, the fourth interlocking portion is configured to receive at least a portion of a lateral tongue of a third interlocking profile of an adjacent panel, the third groove being defined by an upper lip and a lower lip, the lower lip being provided with an upward locking element; the third connecting portion and the fourth connecting portion are configured so that the two panels can be connected to each other by rotational movement; In the connected state, at least a portion of the lateral tongue of the first panel is inserted into the third groove of the adjacent second panel, and at least a portion of the upward locking element of the second panel is inserted into the second downward groove of the first panel.

[0011] To form a strong connection at the apex, the panels are in contact with each other at the upper contact surfaces. Preferably, these upper contact surfaces are substantially plane-parallel, and both contact surfaces may extend vertically to increase the contact surface. It is often advantageous for at least one upper contact surface to be slightly inclined with respect to the vertical, and this at least one slightly inclined contact surface and the vertical plane may subtend an angle of preferably 0 to 2 degrees, preferably 0 to 1 degree, more preferably 0 to 0.5 degrees, and even more preferably 0 to 0.3 degrees. Preferably, the upper contact surface of the downward tongue extends vertically, and the upper contact surface of the upward flank is inclined downwards away from the upward tongue, and preferably, and here more preferably, the vertical upper contact surface of the downward tongue and the inclined upper contact surface of the upward flank subtend an angle with each other of between 0 degrees and 2 degrees, preferably between 0 degrees and 1 degree, more preferably between 0 degrees and 0.5 degrees, and even more preferably between 0 degrees and 0.3 degrees. It is also envisioned that the upper contact surface of the upward flank extends vertically, and the upper contact surface of the downward tongue slopes downward toward the lower flank. Preferably, the sloped upper contact surface of the downward tongue and the vertical upper contact surface of the upward flank mutually subtend an angle 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. It is further contemplated that the upper contact surface of the downward tongue and the upper contact surface of the upward flank are each at least partially sloped with respect to a vertical plane (i.e., a plane perpendicular to the panels). This slope is preferably such that both of the respective upper contact surfaces slope downward away from each other. A technical effect of these embodiments is a more concentrated contact of the upper contact surfaces at the top seam formed between the panels, which facilitates the creation of a watertight barrier. Furthermore, the aforementioned slope typically reduces sensitivity to tolerances and precision during manufacturing and connection. The slightly sloped upper contact surfaces prevent squeaking between the interconnected panels, and the slope also provides a stronger or better connection between the interconnected panels at the top.The apex is where the panels are configured to make full contact when joined together.

[0012] Each upper contact surface is not necessarily the upper surface of each panel, but may for example be provided with a chamfered or beveled top surface or may be grouted, thereby providing a decorative function to the panel surface. Preferably, each upper contact surface is the upper surface where two panels meet.

[0013] Furthermore, in one embodiment, the outer side of the downward tongue includes at least one, preferably trapezoidal, recess between the upper contact surface and the inclined contact surface of the downward tongue, and in the connected state of adjacent panels, the recess is preferably located at a distance from the upper contact surface of the upward flank.

[0014] The recess allows the panel material to expand or swell (locally) and prevents the connection between the two interconnecting panels from being disrupted or coming undone. The recess also serves as an additional dust chamber, preventing dust from disrupting the contact between the upper contact surfaces. The recess may be located between the upper contact surface of the downward tongue and the inclined contact surface of the downward tongue and / or the third locking element, or in the transition between the upper contact surface and the inclined contact surface of the downward tongue and / or the third locking element.

[0015] Preferably, each panel or each connection of each panel is configured to exert a certain locking force, pressing the panels toward each other, in the connected state. Such a locking force can be generated, for example, by a pre-tensioning configuration or by slightly oversizing one connection compared to the other. In the case of floor panels, this generates a horizontal force, i.e., in the direction of the plane of the floor panel. This locking force preferably presses the panels toward each other in the direction of the main plane of the panels, thereby pressing the upper contact surfaces together. This pre-tensioning improves the connection between the panels, preferably creating a watertight seal at the top of each panel.

[0016] The locking or clamping force may cause the area or zone around the inclined contact surfaces of the downward tongue to deform elastically or plastically while adjacent inclined contact surfaces are engaged, the type of deformation typically depending on the material properties of the panels and the specific design of each connection.

[0017] The outer side of the upward tongue may include a first locking element, e.g., in the form of an outward bulge, and the downward flank may include a second locking element, e.g., in the form of a recess, with at least a portion of the first locking element and at least a portion of the second locking element contacting the panel in the coupled state and forming a locking element surface. Thus, the two locking elements can cooperate to provide locking, particularly locking perpendicular to or perpendicular to the (main) faces of the panel. The first and second locking elements are preferably formed integrally with the panel, e.g., milled into the panel material. The application of the mutually cooperating locking elements prevents the two panels from being displaced substantially perpendicularly relative to each other. Either or both of the first and second locking elements are preferably substantially rigidly connected to the rest of the panel, respectively, and do not use relatively weak, resilient locking components that may also experience material fatigue relatively quickly, thereby achieving a relatively durable and strong lock. The first locking element may form an integral part of the upward tongue, where the first locking element may be formed, for example, by a protruding (outwardly bulging) edge deformation or a recessed (inwardly bulging) edge deformation of the upward tongue.

[0018] The first locking element may be an outward bulge, the outer side of which includes an upper portion and an adjacent lower portion, the lower portion including an inclined locking surface, preferably a curved guide surface. The first locking element on the outer side of the upward tongue is a protruding portion of the panel, typically the outermost portion of one panel, that must overcome the force during joining to press one panel into the other, and contacts the downward flank of the other panel during connection. By providing a (curved) guide surface on the upper portion, the further or other panel can be guided downward, allowing the connection to occur gradually and preventing large material deformations and / or peak stresses. Therefore, the lower portion may be inclined, forming a portion that returns from the outermost portion of the bulge toward the upward tongue. This inclined surface also provides a guide function, guiding the panel toward its final stage. The inclination of the locking surface further allows potential upward force or movement of the panel to have vertical and horizontal force components. A horizontal component can be used to bring the panels closer together and press them together to improve the connection between the panels and the waterproof properties of the connection. The second locking element may be a recess including an upper portion and an adjacent lower portion, the lower portion including an inclined locking surface for cooperating with the first locking element. An inclined surface further has the advantage that it is relatively easy to fabricate or process, for example, compared to a rounded surface, and that it is relatively easy to achieve a relatively large contact area between the panels to distribute the locking force across the connected panels. Preferably, each inclined locking surface is a plane (flat surface) that defines a surface, and this plane forms a fold or kink with the curved upper portion of the corresponding locking element. The plane is preferably arranged parallel to the plane formed by the inclined contact surfaces of the panels. For smooth guidance, the outer portion of the upward tongue preferably descends vertically toward and extends to the outward bulge. The intersection of the upper portion of the outward bulge with the vertical outer portion of the upward tongue includes a fold or kink. The outward bulge preferably comprises a curved upper portion, the curve gradually flattening to a substantially vertical line near a lower region of the upper portion.The upper portion extends to the lower portion, the lower portion comprising a flat, inclined locking surface. The inclined locking surface forms a fold or kink with the flattened lower region of the upper portion of the outward bulge. The recess of the downward flank is preferably complementary (form-fitting) to the outward bulge, and thus the upper flank preferably includes a vertical outer portion extending from the upper surface of the downward groove to the recess. The inward recess includes a curved upper portion, the curvature preferably gradually flattening toward a substantially vertical line near the lower region of the upper portion. The inclined locking surface forms a fold or kink with the flattened lower region of the upper portion of the recess. The inclined locking surfaces have substantially the same inclination angle with respect to the vertical.

[0019] Preferably, when adjacent panels are connected, the upper portion of the first locking element and the upper portion of the second locking element are generally spaced apart. This typically results in a situation where, when adjacent panels are connected, the outward bulge and the recess cooperate solely via the inclined locking surface. In this way, the function and effect of the inclined locking surface can be more improved. Preferably, when adjacent panels are connected, only a portion of the inclined locking surface at the bottom of the outward bulge cooperates with only a portion of the inclined locking surface at the bottom of the recess. Preferably, the length of the inclined locking surface at the bottom of the outward bulge is greater than the length of the inclined locking surface at the bottom of the recess, preferably at least 1.5 times greater.

[0020] Preferably, the upper outer portion is preferably substantially vertical and defines an outer vertical surface, and at least a part of the first locking element protrudes horizontally at least partially from the outer vertical surface, preferably by a maximum of 2 mm, more preferably by a maximum of 1 mm. The outer vertical surface typically divides the upwardly facing tongue into an inner section oriented towards the upwardly facing flank and an outer section including the first locking element, the maximum width of the inner section being at least 8 times, preferably at least 10 times, the maximum width of the outer section.

[0021] The first and second locking elements are preferably located at a height position below the height positions of the inclined contact surfaces (if applicable) of the downward tongue and upward flank and / or the third and fourth locking elements (if applicable). This typically reduces the degree of deformation of the joined parts during the joining process and is advantageous for the life and reliability of the joined parts. Preferably, the height positions of the inclined contact surfaces of the downward tongue and upward flank are above the height position of the highest point of the upward tongue. This is typically advantageous for forming a watertight barrier as close to the top surface of the panel as reasonably possible.

[0022] Preferably, at least a part of the upper part of the outward bulge located outside the upward tongue is located at a height position higher than the height position defined by the lowest point of the upward groove, and preferably, at least a part of the upper part of the recess located on the downward flank is located at a height position higher than the height position defined by the lowest point of the upward groove. The inclined contact surfaces of said bulge and recess are preferably located below the lowest point of the upward groove. This typically facilitates the joining process, but can also be advantageous for releasing the joining of interconnected panels by a downward angling movement of the panels relative to each other.

[0023] The upper portion extends over a larger vertical portion than the lower portion, allowing for gradual guiding of the panel into position. Because the upper portion typically does not provide a vertical locking effect (because the upper portion of the outward bulge and the upper portion of the recess are preferably spaced apart when coupled), its horizontal portion is less relevant than the lower portion, which typically provides a vertical locking effect. In the coupled state of the panels, the contacting portions of the first and second locking elements are typically formed by the inclined locking surfaces, i.e., the lower portions, of the locking elements. In the coupled state of the panels, the upper portions of the first and second locking elements may be at least partially spaced apart. This spacing allows the upward movement of the upward tongue to be unimpeded by the downward flank, which can be transferred and converted into a closing horizontal movement, pressing the panels together, to improve the connection or locking of the panels.

[0024] The outer side of the upward-facing tongue may include an upper outer portion and a lower outer portion, with the first locking element disposed between the upper and lower outer portions, the lower outer portion being closer to the inner side of the upward-facing tongue than the upper outer portion. The upper outer portion may preferably be substantially vertical, defining an outer vertical surface, with the first locking element protruding at least partially, preferably by up to 2 mm, from the outer vertical surface. For example, the upper outer portion above the first locking element may define a vertical surface, and the lower outer portion below the first locking element may define another vertical surface that is parallel but offset, with the vertical surface of the lower outer portion positioned closer to the upward flank. This difference creates a relatively large distance between the panels at the intersection between the inclined locking surface of the upward-facing tongue and the lower outer portion, which allows for greater upward angular or rotational movement of the upward-facing tongue and, therefore, potentially greater closing or tension force exerted by the locking element to improve the connection and waterproofing properties of the panels.

[0025] The lower outer portion may be substantially vertical, with the inclined locking surface or lower portion and the lower outer portion subtending an angle between 100 and 175 degrees, particularly between 100 and 150 degrees, and more particularly between 110 and 135 degrees. Such angles have proven to provide the best combination of locking and guiding characteristics. The angle subtended by the upper contact surface and the inclined contact surface and the angle subtended by the lower outer portion and the inclined locking surface or lower portion may be within 20 degrees of each other and are preferably the same. This allows both elements to be machined from the panel using the same or similar tooling, making manufacturing relatively easy.

[0026] The outermost portion of the first locking element may be positioned at a lower horizontal height than the upward groove, so that when the panels move downward during connection, the widest or outermost portion of the first locking element comes into contact relatively late, facilitating connection of the two panels.

[0027] Preferably, below and preferably adjacent to the upper contact surfaces of the downward tongue and upward flank, an outer portion of the downward tongue includes a third locking element, and the upward flank includes a fourth locking element, and in a coupled state of adjacent panels, at least a portion of the third locking element of one panel contacts at least a portion of the second locking element of another panel to lock the panels relative to each other, preferably vertically. Preferably, in a coupled state of adjacent panels, the upper contact surfaces define an inner vertical surface, and the third and fourth locking elements are arranged on the same, more preferably a single, side of the inner vertical surface facing away from the upward tongue. Preferably, the third and fourth locking elements extend horizontally relative to the inner vertical surface by a maximum of 1 mm, preferably a maximum of 0.5 mm, more preferably a maximum of 0.2 mm. Each of the third and fourth locking elements may include a bulge and / or a recess, and preferably the third locking element includes a bulge and the fourth locking element includes a recess.

[0028] Preferably, the third and fourth locking elements are at a height position above the height position of the highest point of the upward tongue, which reduces material deformation and therefore material stress during coupling and uncoupling. Preferably, the first and second locking elements are at a height position below the height position of the third and fourth locking elements, which (also) reduces material deformation and therefore material stress during coupling and uncoupling.

[0029] The outer side of the downward tongue preferably includes at least one recess between the upper contact surface of the downward tongue and the third locking element, and in the coupled state of adjacent panels, the recess is preferably located at a distance from the upper contact surface of the upward flank. The recess allows the panel material to expand (locally) and prevents the connection between the two interlocking panels from being disturbed or disengaged. The recess also serves as an additional dust chamber to prevent dust from disturbing the contact of the upper contact surface. The recess may be located between the upper contact surface of the downward tongue and the third locking element of the downward tongue, or at the transition between the upper contact surface and the third locking element.

[0030] Adjacent to each upper contact surface, typically directly adjacent to or immediately below each upper contact surface, there may be a sloped contact surface. At each slope, the panels come into contact and connect or seal the panels together. The slope is preferably such that when looking at the downward tongue, the slope extends outward, and when looking at the upward flank, the slope extends inward. The slope angle is such that the downward tongue has a protrusion and the upward flank has a recess, which, when in a mated state, come into contact and provide a vertical locking effect. The slope also creates a slight labyrinth, which improves the watertightness of the connection.

[0031] Preferably, the inclined contact surface of the downward tongue extends horizontally by at most 1 mm, preferably at most 0.5 mm, more preferably at most 0.2 mm relative to the inner vertical plane defined by the (contact portions of) the upper contact surfaces of the two panels in the joined state. Preferably, the height positions of the inclined contact surfaces of the downward tongue and the upward flank are higher than the height position of the highest point of the upward tongue. This reduces material stress during the joining process and is advantageous for the reliability of the durability of the connection between adjacent panels. Typically, the inclined contact surface of the downward tongue defines at least a part of the third locking element, and the inclined contact surface of the upward flank defines at least a part of the fourth locking element.

[0032] Proximate, typically directly adjacent to, or immediately below the inclined contact surface, the downward tongue may include an outer surface. This outer surface may be, for example, the outermost surface of the downward tongue, or the surface of the outward tongue that is furthest from the downward flank. Similarly, proximate, typically directly adjacent to, or immediately below the inclined contact surface, the upward flank includes an inner surface. A space exists between the inner surface and the outer surface. The purpose of this space is to prevent forces acting on or exerted by each panel from pressing the panels together at locations other than the respective upper contact surface and / or the respective inclined contact surface. Contact between the inner surface and the outer surface would prevent the upper contact surfaces from contacting each other, which would adversely affect the watertightness of the connection. Thus, at the top, at the respective upper contact surface and the respective inclined contact surface, the purpose is to connect the panels together, while below these contact surfaces, the purpose is to avoid such a connection.

[0033] Each upper contact surface may be at least partially vertically oriented and define an inner vertical surface, with the inclined contact surface of the downward tongue extending horizontally beyond the inner vertical surface, preferably by at most 1 mm, and the inclined contact surface of the upward flank being located inward of the inner vertical surface. Such a configuration allows the downward tongue to locally protrude from the inner vertical surface and the upward flank to locally recess, such that in a coupled state, the inclined contact surfaces grip behind each other to provide a vertical locking effect. By limiting the horizontal protrusion, the downward tongue can provide a vertical locking effect while still allowing coupling by downward or vertical movement. Thus, a portion of the downward tongue may extend beyond the inner vertical surface, the portion being elongated, with the vertical portion being greater than the horizontal portion, preferably at least three times the horizontal portion. This allows for a relatively small horizontal section, yet still allows the panels to be connected by vertical or downward movement.

[0034] Thus, a portion of the downward tongue may extend beyond the inner vertical surface, and the portion may be generally trapezoidal or wedge-shaped, such that the portion provides a robust portion on the face of each panel that wedges into the space provided in the upward flank under locking, interlocking, or other forces, thereby providing a tighter connection between the panels and thereby improving the watertightness of the connection between the panels.

[0035] The inclined contact surfaces can be located outside and / or adjacent to the inner vertical surface, and preferably are located entirely outside the inner vertical surface or entirely to one side of the inner vertical surface. This allows for a relatively simple structure that provides a tight connection between the two panels. Preferably, the upper contact surface that defines the vertical surface transitions directly into the inclined contact surface. In this configuration, the connection of the contact surfaces continues from the upper contact surface to the inclined contact surface, increasing the uninterrupted surface, thereby improving the connection between the panels and the waterproof properties of the connection.

[0036] In the connected state, the bottom of the downward tongue can contact the upper side of the upward groove at the groove contact surface, and a gap extending from the inclined contact surface to the groove contact surface exists between the first and second connecting portions. Such a gap can be used, for example, to collect dust or shavings from the panels that may be generated when connecting two panels. Furthermore, such a gap is intended to prevent forces exerted on or by the panels from pressing the panels together at locations other than the upper contact surface and / or the inclined contact surface. The groove contact surface is preferably primarily horizontal, allowing downward forces exerted on the panels, particularly at the connection between two panels, typically by stepping on the panel, to be transmitted to the subfloor or surface below the panels. The upward groove and the downward tongue are preferably formed so that the gap between the groove contact surface and the outward-facing surface of the bottom of the downward tongue spans the gap width, which preferably extends across at least one-quarter, more preferably at least one-third, and even more preferably more than half of the groove width. The groove width is defined by the smallest horizontal width between the outer surface of the upturned tongue and the upturned flank.

[0037] The upper surface of the upward tongue and the upper surface of the downward groove may be spaced apart from each other in the mated state, such that a gap exists between the two surfaces. Again, this gap is intended to prevent any force exerted on or by the panels from pushing the panels together at locations other than the upper contact surface and / or the inclined contact surface. Upward movement of the upward tongue may, for example, result in a horizontal force that closes or tightens the connection between the two panels, more particularly a so-called closed-groove locking connection. To allow this upward movement, a gap is formed between the upward tongue and the downward groove. The upper surface of the downward groove may, for example, be formed by the bottom surface of a bridge portion connecting the downward tongue to the rest of the panel.

[0038] The upper contact surface and the inclined contact surface of the upward flank may mutually enclose a first angle, and the upper contact surface and the inclined contact surface of the downward tongue may mutually enclose a second angle, with the first and second angles being within 20 degrees of each other. For example, the inclined contact surface of the upward flank may mutually enclose a first angle of 120 degrees, and the upper contact surface and the inclined contact surface of the downward tongue may mutually enclose a second angle of 125 degrees. The difference between these two angles is 5 degrees, which is within 20 degrees of each other. By providing a difference between the angles, a configuration can be provided in which a wedging action can be achieved to increase the locking force and watertight properties of the connection. Pressing or wedging the locking members together can increase the locking force or connection of the panels.

[0039] Preferably, in the connected state of adjacent panels, a space exists between at least a part of the outer surface of said panel and at least a part of the inner surface of the adjacent panel. Preferably, the outer side of the upward tongue includes an upper outer portion defining an outer vertical surface dividing the upward tongue into an inner section directed towards the upward flank and an outer section including a first locking element, the maximum width of the inner section being at least 8 times, preferably at least 10 times, the maximum width of the outer section. This limits the effective width of the first locking element, facilitating the connecting process and reducing the degree of material deformation during the connecting process, which is advantageous for the reliability and durability of the connection of the interconnected panels.

[0040] The panel according to the present invention may be, for example, at least partially made of or based on magnesium oxide. The panel according to the present invention may comprise a core having an upper side and a lower side, and a decorative top structure (or top) attached directly or indirectly to the upper side of the core, the core comprising at least one composite layer containing at least one magnesium oxide (magnesia) and / or magnesium hydroxide-based composition, in particular magnesia cement. Particles, in particular cellulose- and / or silicone-based particles, may be dispersed in the magnesia cement. Optionally, one or more reinforcing layers, such as glass fiber layers, may be embedded in the composite layer. The core composition may comprise magnesium chloride, resulting in magnesium oxychloride (MOC) cement, and / or magnesium sulfate, resulting in magnesium oxysulfate (MOS) cement.

[0041] It has been found that the application of magnesia cement containing magnesium oxide and / or magnesium hydroxide-based compositions, particularly MOS and MOC, significantly improves the flammability (non-combustibility) of such decorative panels. Furthermore, the relatively fire-resistant panels also exhibit significantly improved dimensional stability during temperature fluctuations during normal use. Magnesia-based cement is a cement primarily composed of magnesia (magnesium oxide), which is the reaction product of a chemical reaction in which magnesium oxide acts as one of the reactants. In magnesia cement, the magnesia may still be present and / or may have undergone a chemical reaction in which additional chemical bonds are formed, as will be explained in more detail below. Further advantages of magnesia cement compared to other cement types are listed below. A first additional advantage is that magnesia cement can be produced in a relatively energy-efficient, and therefore cost-efficient, manner. Furthermore, magnesia cement has relatively high compressive and tensile strength. Another advantage of magnesia cement is its natural affinity with typically inexpensive cellulose materials, such as plant fiber powder (wood dust) and / or wood chips. This not only improves the magnesia cement's binding, but also its lighter weight and sound insulation (attenuation). Magnesium oxide, when combined with cellulose and, optionally, clay, creates a magnesia cement that absorbs water vapor and efficiently expels moisture, preventing deterioration (rot). Furthermore, magnesia cement is a relatively good thermal and electrical insulator, making the panels particularly suitable for use as flooring in radar stations and hospital operating rooms. A further advantage of magnesia cement is its relatively low pH compared to other cement types, which allows for the primary durability of glass fibers as dispersed particles in the cement matrix and / or as a reinforcing layer (as glass fibers), and also allows for the use of other types of fibers in a durable manner. Another advantage of decorative panels is their suitability for both indoor and outdoor use.

[0042] As already mentioned, magnesia cement is based on magnesium oxide and / or magnesium hydroxide. The magnesia cement itself may not contain magnesium oxide, depending on the additional reactants used to produce the magnesia cement. Here, for example, it is quite conceivable that magnesia as a reactant is converted to magnesium hydroxide during the manufacturing process of magnesia cement. Therefore, the magnesia cement itself may contain magnesium hydroxide. Typically, magnesia cement contains water, in particular hydration water. Water is usually used as a binder to form a strong and cohesive cement matrix.

[0043] Magnesia-based compositions, particularly magnesia cement, may contain magnesium chloride (MgCl2). Typically, magnesia cement containing magnesium oxychloride (MOC) is formed when magnesia (MgO) is mixed with magnesium chloride in an aqueous solution. The binder phases are Mg(OH)2, 5Mg(OH)2·MgCl2·8H2O (form 5), 3Mg(OH)2·MgCl2·8H2O (form 3), and Mg2(OH)ClCO3·3H2O. The latter phase is preferred due to its superior mechanical properties. Compared to other cements, such as Portland cement, MOC offers superior properties. It does not require wet curing, has high fire resistance, low thermal conductivity, and excellent abrasion resistance. MOC cement can be used with a variety of aggregates (additives) and fibers, has excellent adhesion resistance, and can be surface-treated. MOC develops high compressive strength (e.g., 8,000-10,000 psi) within 48 hours. The increase in compressive strength occurs early in the cure process, and after 48 hours the strength is at least 80% of the ultimate strength. The compressive strength of MOC is preferably between 40 and 100 N / mm. 2 The bending tensile strength is preferably between 10 and 17 N / mm 2 The surface hardness of the MOC is preferably 50 to 250 N / mm 2 The elastic modulus (E-modulus) is preferably 1 to 3. 4 N / mm 2Although the flexural strength of MOC is relatively low, it can be significantly improved by the addition of fibers, especially cellulose-based fibers. MOC is compatible with a wide variety of plastic fibers, mineral fibers (e.g., basalt fiber), and organic fibers such as bagasse, wood fiber, and hemp. The MOC used in the panels of the present invention can be reinforced with one or more of these fibers. MOC is non-shrinkable, abrasion-resistant, impact-resistant, dent-resistant, and scratch-resistant. MOC is resistant to heat and freeze-thaw cycles and does not require air entrapment for improved durability. MOC also has excellent thermal conductivity, low electrical conductivity, and excellent bonding to various substrates and additives, and possesses acceptable fire resistance properties. Exposure of panels to relatively extreme weather conditions (temperature and humidity) is less preferable because these conditions affect not only the curing properties but also the phase development of the magnesium oxychloride. Over a period of time, atmospheric carbon dioxide reacts with the magnesium oxychloride, forming a surface layer of Mg2(OH)ClCO3·3H2O. This layer serves to slow the leaching process until further leaching occurs, forming hydromagnesite (4MgO 3CO3 4H2O), which is insoluble and allows the cement to maintain its structural integrity.

[0044] Magnesium-based compositions, especially magnesia cements, can be based on magnesium sulfate, specifically the heptahydrate sulfate mineral epsomite (MgSO4·7H2O). This latter salt is also known as Epsom salt. In aqueous solution, MgO reacts with MgSO4 to produce magnesium oxysulfate cement (MOS), which has excellent bonding properties. In MOS, 5Mg(OH)2·MgSO4·8H2O is the most commonly found chemical phase. While MOS is not as strong as MOC, it begins to decompose at temperatures more than twice those of MOC, improving its fire resistance and making it suitable for fire-stopping applications. Furthermore, its decomposition products at high temperatures are less toxic (sulfur dioxide) and less corrosive than oxychlorides (hydrochloric acid). Furthermore, weather conditions (humidity, temperature, wind) during construction are less critical for MOS than for MOC. 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 that contribute to the mechanical strength of MOS cements have been found to exist in the ternary system MgO·MgSO₄·H₂O at temperatures ranging from 30 to 120°C: 5Mg(OH)₂·MgSO₄·3H₂O (513 phase), 3Mg(OH)₂·MgSO₄·8H₂O (318 phase), Mg(OH)₂·2MgSO₄·3H₂O (123 phase), and Mg(OH)₂·MgSO₄·5H₂O (115 phase). Typically, the 513 and 318 phases can only be obtained by fixing the molar ratio of MgO to MgSO₄ (approximately) 5:1 and curing the cement under saturated steam. The 318 phase has been found to be preferable in applied MOS because it contributes significantly to mechanical strength and is stable at room temperature. This also applies to the 513 phase. The 513 phase typically has a microstructure that includes needle-like structures. This can be confirmed by SEM analysis. The magnesium oxysulfate (5Mg(OH)2·MgSO4·3H2O) needles can be substantially uniformly formed and typically have lengths of 10-15 μm and diameters of 0.4-1.0 μm. When referring to a needle-like structure, flake and / or whisker structures can also be included.While it may not be practical to obtain MOS containing more than 50% of the 513 or 318 phases, adjusting the crystalline phase composition can improve the mechanical strength of the MOS. Preferably, the magnesia cement contains at least 10%, preferably at least 20%, and more preferably at least 30% of 5Mg(OH)2·MgSO4·3H2O (513 phase). This preferred embodiment provides magnesia cement with sufficient mechanical strength for use in the core layer of floor panels.

[0045] The crystalline phase of MOS can be adjusted by modifying it with organic acids, preferably citric acid and / or phosphoric acid and / or phosphate salts. During this modification, new MOS phases are obtained, which can be represented by 5Mg(OH)₂·MgSO₄·5H₂O (515 phase) and Mg(OH)₂·MgSO₄·7H₂O (517 phase). The 515 phase is obtained by modifying MOS with citric acid. The 517 phase is obtained by modifying MOS with phosphoric acid and / or phosphate salts (H₃PO₄, KH₂PO₄, K₃PO₄, K₂HPO₄). These 515 and 517 phases can be determined by chemical elemental analysis, and SEM analysis demonstrates that the microstructures of both the 515 and 517 phases are water-insoluble needle-like crystals. In particular, the addition of citric acid can improve the compressive strength and water resistance of MOS. Therefore, when applied to panels according to the present invention, MOS preferably contains 5Mg(OH)2·MgSO4·5H2O (515 phase) and / or Mg(OH)2·MgSO4·7H2O (517 phase). As mentioned above, the addition of phosphoric acid and phosphates can extend the setting time of MOS cement and improve its compressive strength and water resistance by altering the hydration process and phase composition of MgO. Here, phosphoric acid or phosphates ionize in solution to form H2PO4 - ,HPO4 2- and / or PO4 3- These anions form [Mg(OH)(HO) x ] +The addition of phosphoric acid or phosphates to MOS cement results in a compact structure, high mechanical strength, and good water resistance. + The order follows: >>K2HPO4 >>K3PO4. MOS has better volume stability, less shrinkage, better bonding properties, and less corrosion resistance under a much wider range of weather conditions than MOC, and may therefore be preferable to MOS. The density of MOS is typically 350-650 kg / m 3 The bending tensile strength is preferably 1 to 7 N / mm 2 is.

[0046] The magnesium cement composition preferably includes one or more silicone-based additives. Various silicone-based additives may be used, including, but not limited to, silicone oil, neutral-cure silicone, silanol, silanol fluid, 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 its derivatives). Neutral-cure silicones include silicones that release alcohol or other volatile organic compounds (VOCs) upon curing. Other silicone-based additives and / or siloxanes (e.g., siloxane polymers) may also be used, including, but not limited to, hydroxyl (or hydroxy)-terminated siloxanes and / or siloxanes terminated with other reactive groups, acrylic siloxanes, urethane siloxanes, epoxy siloxanes, and mixtures and derivatives thereof. As described in more detail below, one or more crosslinkers (e.g., silicone-based crosslinkers) may also be used. The viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) may be about 100 cSt (at 25° C.), which is referred to as a low viscosity. In another embodiment, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is about 20 cSt (at 25° C.) to about 2000 cSt (at 25° C.). In another embodiment, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is about 100 cSt (at 25° C.) to about 1250 cSt (at 25° C.). In another embodiment, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is about 250 cSt (at 25° C.) to 1000 cSt (at 25° C.). In yet another embodiment, the viscosity of one or more silicone-based additives (eg, silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is between about 400 cSt (25° C.) and 800 cSt (25° C.).And, in certain embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is about 800 cSt (25°C) to about 1250 cSt (25°C). One or more silicone-based additives having higher and / or lower viscosities may also be used. For example, in further embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is about 20 cSt (25°C) to about 200,000 cSt (25°C), about 1,000 cSt (25°C) to about 100,000 cSt (25°C), or about 80,000 cSt (25°C) to about 150,000 cSt (25°C). In other embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is from about 1,000 cSt (25° C.) to about 20,000 cSt (25° C.), from about 1,000 cSt (25° C.) to about 10,000 cSt (25° C.), from about 1,000 cSt (25° C.) to about 2,000 cSt (25° C.), or from about 10,000 cSt (25° C.) to about 20,000 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 polymer, etc.) is from about 1,000 cSt (25° C.) to about 80,000 cSt (25° C.), from about 50,000 cSt (25° C.) to about 100,000 cSt (25° C.), or from about 80,000 cSt (25° C.) to about 200,000 cSt (25° C.). And in further embodiments, the viscosity of one or more silicone-based additives (e.g., silicone oil, neutral cure silicone, silanol fluid, siloxane polymer, etc.) is from about 20 cSt (25° C.) to about 100 cSt (25° C.). Other viscosities may also be used, as desired.

[0047] In preferred embodiments, magnesium cement compositions, particularly magnesium oxychloride cement compositions, include a single type of silicone-based additive. In other embodiments, mixtures of two or more types of silicone-based additives are used. For example, in some embodiments, magnesium oxychloride cement compositions may include a mixture of one or more silicone oils and neutral-curing silicones. In certain embodiments, the ratio of silicone oil to neutral-curing silicone may be about 1:5 to about 5:1 by weight. In other such embodiments, the ratio of silicone oil to neutral-curing silicone may be about 1:4 to about 4:1 by weight. In other such embodiments, the ratio of silicone oil to neutral-curing silicone may be about 1:3 to about 3:1 by weight. In still other such embodiments, the ratio of silicone oil to neutral-curing silicone may be about 1:2 to about 2:1 by weight. In still further such embodiments, the ratio of silicone oil to neutral-curing silicone may be about 1:1 by weight.

[0048] It is contemplated that one or more crosslinking agents may be used in the magnesia cement. In some embodiments, the crosslinking agent is a silicone-based crosslinking agent. Exemplary crosslinking agents include, but are not limited to, methyltrimethoxysilane, methyltriethoxysilane, methyltris(methylethylketoximino)silane, and mixtures and derivatives thereof. Other crosslinking agents (including other silicone-based crosslinking agents) may also be used. In some embodiments, the magnesium oxychloride cement composition includes 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 the one or more silicone-based additives (e.g., silanols and / or silanol fluids) to the crosslinking agent may be about 1:20 to about 20:1 by weight, about 1:10 to about 10:1 by weight, or about 1:1 to about 10:1 by weight.

[0049] Magnesium (oxychloride) cement compositions containing one or more silicone-based additives may exhibit reduced sensitivity to water compared to conventional magnesium (oxychloride) cement compositions. Furthermore, in some embodiments, magnesium (oxychloride) cement compositions containing one or more silicone-based additives may exhibit little or no sensitivity to water. Magnesium (oxychloride) cement compositions containing one or more silicone-based additives may further exhibit hydrophobicity and water resistance.

[0050] Magnesium (oxychloride) cement compositions containing one or more silicone-based additives may also exhibit improved hardening characteristics. For example, magnesium (oxychloride) cement compositions may harden to form various reaction products, including the 3Mg(OH)₂·MgCI₂·8H₂O (Phase 3) and 5Mg(OH)₂·MgCl₂·8H₂O (Phase 5) crystal structures. In some situations, a higher proportion of the 5Mg(OH)₂·MgCl₂·8H₂O (Phase 5) crystal structure is preferred. In such situations, the addition of one or more silicone-based additives to a magnesium oxychloride cement composition may stabilize the hardening process, which may increase the percent yield of the 5Mg(OH)₂·MgCl₂·8H₂O (Phase 5) crystal structure. For example, in some embodiments, magnesium oxychloride compositions containing one or more silicone-based additives may harden to form greater than 80% of the 5Mg(OH)₂·MgCI₂·8H₂O (Phase 5) crystal structure. In other embodiments, magnesium oxychloride compositions containing one or more silicone-based additives may cure to form greater than 85% of the 5Mg(OH)2·MgCI2·8H2O (Phase 5) crystal structure. In yet other embodiments, magnesium oxychloride compositions containing one or more silicone-based additives may cure to form greater than 90% of the 5Mg(OH)2·MgCI2·8H2O (Phase 5) crystal structure. In yet other embodiments, magnesium oxychloride compositions containing one or more silicone-based additives may cure to form greater than 95% of the 5Mg(OH)2·MgCl2·8H2O (Phase 5) crystal structure. In yet other embodiments, magnesium oxychloride compositions containing one or more silicone-based additives may cure to form greater than 98% of the 5Mg(OH)2·MgCI2·8H2O (Phase 5) crystal structure. In yet other embodiments, magnesium oxychloride compositions containing one or more silicone-based additives may cure to form about 100% 5Mg(OH)2·MgCI2·8H2O (Phase 5) crystal structure.

[0051] Furthermore, magnesium (oxychloride) cement compositions containing one or more silicone-based additives may also exhibit improved strength and bonding properties. If desired, magnesium (oxychloride) cement compositions containing one or more silicone-based additives may also be used to produce relatively thin magnesium (oxychloride) cement or concrete structures. For example, magnesium (oxychloride) cement compositions containing one or more silicone-based additives may be used to produce cement or concrete structures or layers having a thickness of less than 8 mm, preferably less than 6 mm.

[0052] In some cases, temporary deformation of the joints may be desired and / or required to achieve interlocking between the joints, and as a result, mixing magnesium oxide and / or magnesium hydroxide and / or magnesium chloride and / or magnesium sulfate with one or more silicone-based additives can be beneficial because it provides an increased degree of flexibility and / or elasticity. For example, in some embodiments, cement and concrete structures formed using magnesium oxychloride cement compositions can bend or flex without cracking or breaking.

[0053] Magnesium (oxychloride) cement compositions containing one or more silicone-based additives may further include one or more additional additives. The additional additives may be used to enhance certain properties of the composition. For example, in some embodiments, additional additives may be used to make structures formed using the disclosed magnesium oxychloride cement compositions appear like stone (e.g., granite, marble, sandstone, etc.). In certain embodiments, the additional additives may include one or more pigments or colorants. In other embodiments, additional additives may include fibers, including, but not limited to, paper fibers, wood fibers, polymer fibers, organic fibers, and glass fibers. The magnesium oxychloride cement compositions may also form UV-stable structures whose color and / or appearance do not undergo substantial fading from UV light over time. Other additives may also be included in the composition, including, but not limited to, plasticizers (e.g., polycarboxylic acid plasticizers, polycarboxylic acid ether plasticizers, etc.), surfactants, water, and mixtures and combinations thereof. As indicated above, magnesium oxychloride cement compositions, if applied, may contain magnesium oxide (MgO), aqueous magnesium chloride (MgCl(aq)), and one or more silicone-based additives. Instead of aqueous magnesium chloride (MgCl), magnesium chloride (MgCl) powder may also be used. For example, magnesium chloride (MgCl) powder may be used in combination with an amount of water equivalent to or similar to the amount of aqueous magnesium chloride (MgCl(aq)) added.

[0054] In certain embodiments, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride solution (MgCl(aq)), if applicable, in the magnesium oxychloride cement composition may vary. In some such embodiments, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride solution (MgCl(aq)) is from about 0.3:1 to about 1.2:1 by weight. In other embodiments, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride solution (MgCl(aq)) is from about 0.4:1 to about 1.2:1 by weight. And in still other embodiments, the ratio of magnesium oxide (MgO) to aqueous magnesium chloride solution (MgCl(aq)) is from about 0.5:1 to about 1.2:1 by weight.

[0055] Aqueous magnesium chloride solution (MgCl(aq)) can be described as (or derived from) a magnesium chloride brine solution. Aqueous magnesium chloride solution (MgCl(aq)) (or magnesium chloride brine) may also contain relatively small amounts of other compounds or substances, including, but not limited to, magnesium sulfate, magnesium phosphate, hydrochloric acid, phosphoric acid, etc.

[0056] In preferred embodiments, the amount of one or more (liquid) silicone-based additives in the magnesium oxychloride cement composition can be defined as the ratio of silicone-based additive to magnesium oxide (MgO). For example, in some embodiments, the weight ratio of silicone-based additive to magnesium oxide (MgO) is between 0.06 and 0.6.

[0057] It is also possible, and more preferably, to incorporate at least one oil, such as linseed oil or silicon oil, into the core layer. This increases the flexibility of the magnesium-based core layer and / or thermoplastic-based core layer, reducing the risk of breakage. Instead of or in addition to oil, it is also possible to incorporate one or more water-soluble polymers or polycondensation (synthetic) resins, such as polycarboxylic acids, into the core layer. This has the advantage of preventing the panel from shrinking during drying / curing / solidification, thereby preventing crack formation, and also imparting hydrophobic properties to the core layer after drying / curing / solidification, thereby preventing water (moisture) penetration during subsequent storage and use.

[0058] It is envisioned that the core layer comprises polycaprolactone (PCL). This biodegradable polymer is particularly preferred because it has been found to be meltable by the exothermic reaction of the reaction mixture. It has a melting point of approximately 60°C. PCL can be low-density or high-density. The latter is particularly preferred because it produces a stronger core layer. Alternatively, or in addition, other polymers may be used, preferably polymers selected from the group consisting of other 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-co-caprolactone), poly(lactic acid-co-trimethylene carbonate), poly(sebacic acid-co-ricinoleic acid), and combinations thereof.

[0059] Alternatively, the panel, particularly the core layer, can be made at least in part from PVC, PET, PP, PS, or (thermoplastic) polyurethane (PUR). PS can be in the form of expanded PS (EPS) to further reduce the panel's density, which reduces costs and makes the panel easier to handle. Preferably, at least a portion of the polymer used is formed from recycled thermoplastics, such as recycled PVC or recycled PUR. Recycled PUR can be made based on recyclable polymers, such as recyclable PET. PET can be chemically recycled by glycolysis or depolymerization of PET into monomers or oligomers, and then ultimately to polyurethane polyol. It is also envisioned that rubber and / or elastomer moieties (particles) can be dispersed within at least one composite layer to at least partially improve flexibility and / or impact resistance. It is also conceivable to use a mixture of virgin and recycled thermoplastic materials to construct at least a portion of the core. Preferably, in this mixture, the virgin and recycled thermoplastic materials are essentially the same. For example, such a blend may be entirely PVC-based or entirely PUR-based. The core, when composed of multiple sections / layers, may be solid or foamed, or both.

[0060] 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 microns, preferably 4 to 5 microns. That is, each individual granule preferably has micropores. Preferably, the micropores are interconnected. Preferably, they are not limited to the surface of the granule, but are found substantially throughout the entire cross section of the granule. Preferably, the size of the granules is 200 to 900 microns, preferably 250 to 850 microns, particularly 250 to 500 microns or 500 to 850 microns. Preferably, granules of at least two different sizes are used, most preferably two granules. Preferably, small granules and / or large granules are used. The small granules may have a size range of 250 to 500 microns. Preferably, the large granules have a diameter of 500 to 850 microns. The granules may each be substantially the same size, or may be of two or more predetermined sizes. Alternatively, two or more distinct size ranges may be used, with particles of various different sizes within each range. Preferably, two different sizes or size ranges are used. Preferably, each granule contains a plurality of microparticles, with each microparticle substantially partially fused with one or more adjacent microparticles to form a lattice defining a micropore. Each microparticle preferably has an average size of 1 to 10 microns, with an average of 4 to 5 microns. Preferably, the average size of the micropores is 2 to 8 microns, most preferably 4 to 6 microns. The micropores may be irregularly shaped. Thus, the size of the micropores, and indeed the size of the midi-pores referred to below, is determined by adding the narrowest diameter of the pore to the widest diameter of the pore and dividing by two. Preferably, the ceramic material is uniformly distributed throughout the cross-section of the core layer, i.e., substantially no agglomerates of ceramic material are formed. Preferably, the microparticles have an average size of at least 2 or 4 microns, and / or less than 10 or less than 6 microns, most preferably 5 to 6 microns. It has been found that in this particle size range, the formation of micropores can be controlled.

[0061] The granules may also contain a plurality of substantially spherical mesopores having an average diameter of 10 to 100 microns. These substantially increase the total porosity of the ceramic material without compromising the mechanical strength of the material. The mesopores are preferably interconnected via a plurality of micropores. That is, the mesopores may be in fluid communication with each other via the micropores. The average porosity of the ceramic material is preferably at least 50%, more preferably greater than 60%, and most preferably 70 to 75%. The ceramic material used to prepare the granules may be any (non-toxic) ceramic known in the art, such as calcium phosphate or glass ceramic. The ceramic may be a silicate, but is preferably calcium phosphate, particularly [α]- or [β]-tricalcium phosphate, or hydroxyapatite, or a mixture thereof. Most preferably, the mixture is hydroxyapatite and [β]-tricalcium phosphate, especially more than 50% w / w [β]-tricalcium, most preferably 85% [β]-tricalcium phosphate and 15% hydroxyapatite. Most preferably, the material is 100% hydroxyapatite. Preferably, the cement composition or dry premix contains 15-30% by weight of granules based on the total dry weight of the composition or premix.

[0062] The porous particles can lower the average density of the core layer, thus resulting in a weight reduction that is favorable from an economic and handling standpoint. Furthermore, the presence of the porous particles in the core layer typically increases the porosity of the porous top and bottom surfaces of the core layer, at least to some extent, which is beneficial for attaching additional layers to the top and / or bottom surfaces of the core layer, such as a primer layer, an (initially liquid) adhesive layer, or another decorative or functional layer. Often, these layers are initially applied in a liquid state, and the pores allow the liquid material to be absorbed (permeated) into the pores, thereby increasing the contact surface area between the layers and therefore improving the adhesive strength between the layers.

[0063] The panel may, for example, comprise a layer structure having a central core (or core layer) and at least one decorative top portion directly or indirectly attached to or integrated with the core layer, the top portion forming the top surface of the panel. The top portion preferably comprises at least one decorative layer attached directly or indirectly to the upper surface of the core layer. The decorative layer may be a printed layer, such as a PVC layer, a printed PU layer, or a printed paper layer, and / or may be covered by at least one protective (top) layer covering the decorative layer. The protective layer also constitutes part of the decorative top portion. The presence of the printed and / or protective layer can prevent the tile from being damaged by scratches, environmental factors such as UV rays and moisture, and / or abrasion. The printed layer may be formed by a decoratively printed film, which is applied to a substrate layer and / or an intermediate layer, such as a primer layer, located between the substrate layer and the decorative layer. The print layer may be formed by at least one ink layer applied directly to the top surface of the core layer or a primer layer applied to the substrate layer. The panel may also include at least one wear layer applied directly or indirectly to the top surface of the decorative layer. The wear layer also forms part of the decorative top. Each panel may also include at least one lacquer layer applied directly or indirectly to the top surface of the decorative layer, preferably to the top surface of the wear layer.

[0064] The underside (rear side) of the core(s) may directly constitute the underside (rear side) of the panel. However, it is conceivable, and in some cases even preferable, for the panel to include a backing layer attached directly or indirectly to the underside of the core. Typically, the backing layer functions as a balancing layer to stabilize the shape, particularly the flatness, of such a panel. Furthermore, the backing layer typically contributes to the acoustic damping properties of such a panel. Since the backing layer is typically a closed layer, the attachment of the backing layer to the underside of the core at least partially, preferably completely, covers the core grooves. Here, the length of each core groove is preferably smaller than the length of the backing layer. The backing layer may have a cutout portion, at least a portion of which overlaps with at least one core groove. At least one backing layer is preferably made at least partially from a flexible material, preferably an elastomer. The thickness of the backing layer is typically about 0.1 to 2.5 mm. Non-limiting examples of materials from which the backing layer can be at least partially composed include polyethylene, cork, polyurethane, polyvinyl chloride, and ethylene vinyl acetate. Optionally, the backing layer is made of one or more additives, such as fillers (e.g., chalk), dyes, resins, and / or one or more plasticizers. In certain embodiments, the backing layer is made at least in part of a composite of crushed (or shaved) cork particles bound together by resin. Other tree-related products, such as wood, can be used instead of cork. The thickness of a polyethylene backing layer, for example, is typically 2 mm or less. The backing layer can be solid or foam. A foam backing layer can further improve sound-damping properties. A solid backing layer can improve the desired balance and stability of the panel.

[0065] The inner side of the upward tongue and the inner side of the downward tongue may be in contact with each other in an interlocking manner to transmit force between them, particularly from the upward tongue to the downward tongue. The inner sides of the tongues may be in contact at a tongue contact surface, which may be inclined. The inclination may be such that at least a portion of the inner side of the upward tongue is inclined toward the flank so that a tangent from the tongue contact surface intersects with an inner vertical plane above the tongue contact surface. Alternatively, the inclination may be such that at least a portion of the inner side of the tongue is inclined away from the upward flank so that a tangent from the tongue contact surface intersects with an inner vertical plane below the tongue contact surface. These are closed groove and open groove designs, respectively. The closed groove design can improve locking but is more difficult to interlock, while the open groove design is easier to interlock but does not provide the additional vertical locking of the closed groove design.

[0066] The first and second connectors are located on opposite sides of the panel. The panel may be, for example, rectangular, parallelogram, and / or elongated, and the first and second connectors may be located on both opposite sides of the panel (hence, on all four sides). It is also possible to provide the first and second connectors on only one pair of opposite sides, and other connectors, for example, downwardly angled connectors with lateral tongues and lateral grooves, on the other pair of opposite sides.

[0067] The present invention further relates to a covering, in particular a floor covering, comprising a plurality of panels according to any of the present invention connected to one another.

[0068] The invention will be elucidated on the basis of non-limiting exemplary embodiments shown in the following figures, in which corresponding elements are provided with corresponding reference numerals, in which: [Brief explanation of the drawings]

[0069] [Figure 1]1 is a schematic diagram of two interconnected panels having a first connecting portion and a second connecting portion according to the present invention; FIG. [Figure 2] 2 is a diagram showing a schematic view of a first connecting portion of the panel according to the present invention and FIG. 1; FIG. [Figure 3] FIG. 4 is a diagram schematically illustrating a second connecting portion of the panel according to the present invention. [Figure 4] 1A and 1B are schematic diagrams illustrating an embodiment of two interconnected panels having first and second connectors according to the present invention. [Figure 5] FIG. 5 is a diagram schematically illustrating details of a portion A of the embodiment shown in FIG. 4. [Figure 6] 5 is a diagram schematically illustrating details of a portion B of the embodiment shown in FIG. 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0070] 1 shows a floor panel (1) including a first connecting portion (2) and a second connecting portion (3) in a connected state. The first connecting portion (2) includes an upward tongue (4), an upward flank (5) spaced a certain distance from the upward tongue (4), and an upward groove (6) formed between the upward tongue (4) and the upward flank (5), where the upward groove (6) is adapted to fit a downward tongue (7) of a second connecting portion (3) of another panel (1). The side of the upward tongue (4) facing the upward flank is the inner side (8) of the upward tongue (4), and the side of the upward tongue (4) facing away from the upward flank (5) is the outer side (9) of the upward tongue (4).

[0071] The second connecting portion (3) includes a downward tongue (7), a downward flank (10) provided at a certain distance from the downward tongue (7), and a downward groove (11) formed between the downward tongue (7) and the downward flank (10). The side of the downward tongue (7) facing toward the downward flank (10) is the inner side (12) of the downward tongue (7), and the side of the downward tongue (7) facing away from the downward flank (10) is the outer side (13) of the downward tongue (7).

[0072] The outer side (13) of the downward tongue (7) and the upward flank (5) both include upper contact surfaces (14) at the top of the panel (1), the two upper contact surfaces (14) being in contact and extending vertically. Adjacent to the upper contact surfaces (14), the downward tongue (7) and the upward flank (5) both include inclined contact surfaces (15), the two inclined contact surfaces (15) being in contact, the two upper contact surfaces (14) on the one hand and the two inclined contact surfaces (15) of the outer side (13) of the upward flank (5) and / or downward tongue (7) on the other hand preferably form an angle (α) of approximately 125 degrees with each other. The upper contact surface (14) and the inclined contact surface (15) of the upward flank (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.

[0073] Adjacent to the inclined contact surface (15), the downward tongue (7) includes an outer surface (16), and adjacent to the inclined contact surface (15), the upward flank (5) includes an inner surface (17), the outer surface (16) and the inner surface (17) being parallel and vertically oriented. A space (18) exists between the outer surface (16) and the inner surface (17).

[0074] The two upper contact surfaces (14) define an inner vertical surface (19), and the inclined contact surface (15) of the downward tongue (7) extends beyond the inner vertical surface (19), and the inclined contact surface (15) of the upward flank (5) is located inside the inner vertical surface (19). A portion (20) of the downward tongue (7) extends beyond the inner vertical surface (19), and said portion (20) is approximately trapezoidal or wedge-shaped. The two inclined contact surfaces (15) are located close to the inner vertical surface (19), both of which are completely outside the inner vertical surface (19). The portion (20) is elongated, with the vertical portion being larger than the horizontal portion.

[0075] The bottom (21) of the downward tongue (7) is in contact with the upper part (22) of the upward groove (6) at the groove contact surface (23), and a gap (24) exists between the first connecting part (2) and the second connecting part (3), and the gap (24) extends from the two inclined contact surfaces (15) to the groove contact surface (23). Additionally, the upper surface (25) of the upward tongue (4) and the upper surface (26) of the downward groove (11) are spaced apart from each other, and a gap (27) exists between the two surfaces (25, 26).

[0076] The outer side (9) of the upward tongue (4) includes a first locking element (28), which is in the form of an outward bulge, and the downward flank (10) is provided with a second locking element (29), which is in the form of a recess, and the first locking element (28) and at least a portion of the second locking element (29) are in contact with each other and form a locking element surface (30).

[0077] 2 and 3 show the first and second connectors, respectively. The outer side of the outwardly bulging portion (28) includes an upper portion (31) and an adjacent lower portion (32), the lower portion (32) including an inclined locking surface (30A), and the upper portion (31) including a curved guide surface (32'). The recess (29) includes an upper portion (33) and an adjacent lower portion (34), the lower portion (34) including an inclined locking surface (30B). The upper portions (31, 33) extend in a vertical direction longer than the lower portions (32, 34).

[0078] The contacting portions of the first locking element (28) and the second locking element (29) are the inclined locking surfaces (30, 30A, 30B) of the locking elements (28, 29), and the upper portions (31, 33) of the first locking element (28) and the second locking element (29) are at least partially spaced apart.

[0079] The outer part (9) of the upward tongue (7) includes an upper outer portion (35) and a lower outer portion (36), and the first locking element (28) is disposed between the upper outer portion (35) and the lower outer portion (36). The lower outer portion (36) is disposed closer to the inner part (8) of the upward tongue (4) than the upper outer portion (35).

[0080] The upper outer portion (35) is generally vertical and defines an outer vertical surface (37), from which the first locking element (28) projects. The lower outer portion (36) is generally vertical, and the angled locking surfaces (30A) or lower portion (32) and the lower outer portion (36) form an angle (β) between 100 and 175 degrees. The angle (α) formed by the two upper contact surfaces and the two inclined contact surfaces is generally the same as the angle (β) formed by the lower outer portion (36) and the inclined locking surfaces (30A) or lower portion (32).

[0081] The outermost portion (38) of the first locking element (28) is located at a horizontal height position lower than the upward groove (6).

[0082] FIG. 4 shows a schematic diagram of an embodiment of two interconnected panels (1) having a first connector and a second connector according to the present invention. The two panels (1) include a first connector (2) and a second connector (3) in a connected state. The illustrated embodiment includes all the features shown in FIG. 1 and further includes a recess (40) located below the upper contact surface (14a) of the second connector (3). The recess (40) includes an upper inclined surface and a lower inclined surface. The lower inclined surface is aligned with the inclined contact surface (15a) of the downward tongue (7). The recess (40) may act as an expansion chamber, allowing the panel material to expand, for example, upon exposure to heat and / or moisture, and may also reduce the contact surface area at the top seam between the two panels (1), increasing the clamping force at the top seam between the panels (1) and improving the waterproofness of the panels thus connected.

[0083] Figure 5 shows a schematic detail view of portion A around the upper contact surfaces of two interconnected panels in the embodiment shown in Figure 4. The figure shows two contact points or zones (41, 42), where the engagement force (i.e., clamping force) at this particular region of the connection (2, 3) is higher than at other portions shown in the figure. These two points or zones (41, 42) of concentrated contact significantly improve the waterproofing, thereby further improving the watertight connection between the panels (1). As shown in the figure, the upper contact areas 14b and 14a are not perfectly parallel; rather, the upper contact area 14b is slightly inclined relative to the opposing vertical upper contact area 14a, and more specifically, extends (slightly) away from the vertical upper contact area 14a as it extends downward. This does not necessarily mean that the upper contact regions 14a, 14b are farther apart from each other as they go downwards, but generally results in the effect that the contact between the upper portions of the upper contact regions 14a, 14b is more concentrated compared to the contact between the lower portions of the upper contact regions 14a, 14b.

[0084] It is conceivable that the locking force will cause the area around the inclined contact surface 15a of the downward tongue to deform elastically or plastically while the adjacent inclined contact surfaces are engaged. Locally, the area around the inclined contact surface 15b may also deform elastically or plastically.

[0085] FIG. 6 shows a schematic detail view of part B around the interlocking elements (28, 29) of the two interconnected panels in the embodiment shown in FIG.

[0086] The upper outer portion (35) is generally vertically oriented and defines an outer vertical surface (37), from which the first locking element (28) protrudes. A distance (39a) between the outermost portion (38) of the first locking element (28) and the outer vertical surface (37) is approximately half the distance (39b) between the outermost portion (38) of the second locking element (29) and the vertical surface (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 surface (37) and the upper contact surface is distance D. Distance 39b may be approximately 0.4 times distance D, and distance 39a may be approximately 0.2 times distance D.

[0087] Ordinal numbers such as "first," "second," "third," etc., used in this document are for identification purposes only. Panels of the present 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 be comprised of multiple sublayers, which may include reinforcing layers, such as fiberglass layers. Each joint may also be referred to as a connecting or interlocking profile. "Complementary" interlocking profiles mean that the interlocking profiles can cooperate with one another. However, for this purpose, complementary interlocking profiles do not necessarily have complementary shapes. "Vertical" locking refers to locking in a direction perpendicular to the plane of the panels, and "horizontal" locking refers to locking in a direction perpendicular to the joined edges of the two panels and parallel to or coincident with the plane defined by the panels. In the context of this document, "foam composite material" and "foamed plastic material" (or "expandable plastic material") are interchangeable and, in fact, a foamed composite material comprises a foamed mixture comprising at least one (thermo)plastic material and at least one filler (non-polymeric material).

[0088] The inventive concepts described above are illustrated by several exemplary embodiments. It is contemplated that individual inventive concepts may be applied without applying other details of the described examples. Those skilled in the art will recognize that many inventive concepts can be combined (recombined) to arrive at specific applications, so it is not necessary to detail examples of all possible combinations of the described inventive concepts.

Claims

1. A panel (1), a. at least one first connector (2) and at least one second connector (3) respectively arranged on the sides of opposing panels (1), the first connector (2) of said panel and the second connector (3) of the other panel (1) being arranged to connect by a downward movement; b) the first connecting portion (2) comprises an upward tongue (4), at least one upward flank (5) provided at a distance from the upward tongue (4), and an upward groove (6) formed between the upward tongue (4) and the upward flank (5); the upward groove (6) is adapted to receive at least a part of the downward tongue (7) of the second connecting portion (3) of the other panel (1); the side of the upward tongue (4) facing the upward flank is the inner side (8) of the upward tongue (4); the side of the upward tongue (4) facing away from the upward flank (5) is the outer side (9) of the upward tongue (4); At least a portion of the inner side (8) of the upward tongue (4) is inclined towards the upward flank (5), c) the second connecting portion (3) comprises a downward tongue (7), at least one downward flank (10) provided at a distance from the downward tongue (7), and a downward groove (11) formed between the downward tongue (7) and the downward flank (10); the downward groove (11) is adapted to receive at least a part of the upward tongue (4) of the first connecting portion (2) of another panel (1); the side of the downward tongue (7) facing the downward flank (10) is the inner side (12) of the downward tongue (7); the side of the downward tongue (7) facing away from the downward flank (10) is the outer side (13) of the downward tongue (7); At least a portion of the inner side (12) of the downward tongue (7) is inclined towards the downward flank (10), d. The outer side (13) of the downward tongue (7) and the upward flank (5) both include an upper contact surface (14) near or at the top of the panel (1); At least one of said upper contact surfaces (14) extends at least partially vertically; in a connected state of the panels (1), the upper contact surface (14) of the outer side (13) of the downward tongue (7) of one panel is configured to engage with the upper contact surface (14) of the upward flank (5) of an adjacent panel; e. the outer side (9) of the upward tongue (4) includes a first locking element (28) having an outward bulge; The downward flank (10) is provided with a second locking element (29) having a recess, In the coupled state of adjacent panels, at least a part of the first locking element (28) of one panel and at least a part of the second locking element (29) of another panel come into contact, thereby locking the panels (1) relative to each other; f. the outer portion of said outward bulge (28) includes an upper portion (31) and an adjacent lower portion (32); The lower portion (32) includes a flat, inclined locking surface (30a); The upper portion (31) includes a curved guide surface (32'), the inclined locking surface (30a) forms a fold together with the curved upper portion (31); g. the recess (29) includes a curved upper portion (33) and an adjacent lower portion (34); the lower portion (34) includes a flat, inclined locking surface (30b), which forms a fold together with the curved upper portion (33); h. When adjacent panels are connected, the inclined locking surface (30a) of the lower portion (32) of the outward bulge (28) and the inclined locking surface (30b) of the lower portion (34) of the recess (29) come into contact with each other to provide the locking effect between the panels; In the coupled state of adjacent panels (1), the upper portions (31, 33) of the first locking element (28) and the second locking element (29) are at least partially spaced apart; The outer part (9) of the upward tongue (4) comprises an upper outer part (35) and a lower outer part (36), the first locking element (28) is disposed between the upper outer portion (35) and the lower outer portion (36); the lower outer portion (36) is arranged closer to the inner portion (8) of the upward tongue (4) than the upper outer portion (35); the upper outer portion (35) is generally vertically oriented and defines an outer vertical surface (37); A panel, characterized in that said first locking element (28) projects horizontally at least partially from said outer vertical face (37).

2. 2. A panel (1) according to claim 1, wherein the entire inner side (8) of the upward tongue (4) is inclined towards the upward flank (5) and the entire inner side (12) of the downward tongue (7) is inclined towards the downward flank (10).

3. 3. A panel (1) according to claim 1 or 2, wherein in the connected state of adjacent panels, the upper portions (31, 33) of the first locking element (28) and the second locking element (29) are generally spaced apart.

4. 4. A panel (1) according to claim 1, wherein, in a joined state of adjacent panels, only a portion of the inclined locking surface (30a) of the lower portion (32) of the outward bulge (28) cooperates with only a portion of the inclined locking surface (30b) of the lower portion (34) of the recess (29).

5. 5. A panel (1) according to any one of claims 1 to 4, wherein at least a portion of the upper portion (31) of the outward bulge (28) is located at a height position higher than a height position defined by the lowest point of the upward groove (6), and at least a portion of the upper portion (33) of the recess (29) is located at a height position higher than a height position defined by the lowest point of the upward groove (6).

6. 6. The panel (1) according to claim 1, wherein the length of the inclined locking surface (30a) of the lower portion (32) of the outward bulge (28) is greater than the length of the inclined locking surface (30B) of the lower portion (34) of the recess (29).

7. The upper portions (31, 33) have a vertical section that extends longer than the lower portions (32, 34), 7. A panel (1) according to any one of claims 1 to 6, wherein the height of the upper portions (31, 33) is at least three times the height of the lower portions (32, 34).

8. 8. A panel (1) according to any one of claims 1 to 7, wherein the outermost portion (38) of the first locking element (28) is arranged at a horizontal height position lower than the upwardly directed groove (6).

9. The upper contact surface (14) of the downward tongue (7) extends vertically, the upper contact surface (14) of the upward flank (5) is inclined downwards, away from the upward tongue (4); 9. The panel (1) according to any one of claims 1 to 8, wherein the vertical upper contact surface (14) of the downward tongue (7) and the inclined upper contact surface (14) of the upward flank (5) mutually subtend an angle between 0 and 2 degrees.

10. 10. A panel (1) according to any one of claims 1 to 9, wherein adjacent to the upper contact surface (14), both the downward tongue (7) and the upward flank (5) comprise inclined contact surfaces (15), and in the coupled state of the panels (1), the inclined contact surface (15) of the downward tongue (7) of one panel is configured to engage with the inclined contact surface (15) of the upward flank (5) of an adjacent panel, and wherein each vertical portion of the upper contact surface (14) and each adjacent inclined surface (15) mutually subtend an angle (α) of between 100 and 175 degrees.

11. 11. A panel (1) according to claim 10, wherein the inclined contact surface (15) of the downward tongue defines at least a part of a third locking element and the inclined contact surface (15) of the upward flank (5) defines at least a part of a fourth locking element.

12. 12. A panel (1) according to any one of claims 10 to 11, wherein the downward tongue (7) comprises, adjacent to the inclined contact surface (15), an outer surface (16) that is located below the inclined contact surface (15) of the downward tongue (7), and the upward flank (5) comprises, adjacent to the inclined contact surface (15), an inner surface (17) that is located below the inclined contact surface (15) of the upward flank (5), the outer surface (16) and the inner surface (17) extending substantially parallel, at least partially extending vertically and / or at least partially curved.

13. 13. A panel (1) according to claim 12, wherein in the connected state of adjacent panels, a space (18) exists between at least a portion of the outer surface (16) of the panel (1) and at least a portion of the inner surface (17) of the adjacent panel (1).

14. 14. A panel (1) according to any one of claims 10 to 13, wherein in the connected state of adjacent panels, the bottom (21) of the downward tongue (7) contacts the upper part (22) of the upward groove (6) at a groove contact surface (23), wherein a gap (24) exists between the first connecting portion (2) and the second connecting portion (3), extending from the inclined contact surface (15) to the groove contact surface (23).

15. 15. A panel (1) according to any one of claims 1 to 14, wherein in the connected state of adjacent panels, the bottom (21) of the downward tongue (7) is in approximately horizontal contact with the upper part (22) of the upward groove (6) at a groove contact surface (23), wherein a gap (24) exists between the first connecting portion (2) and the second connecting portion (3) on both sides of the groove contact surface (23).

16. 16. A panel (1) according to any one of claims 1 to 15, wherein in the connected state, the upper surface (25) of the upward tongue (4) and the upper surface (26) of the downward groove (11) are at least partially separated from each other so that a gap (27) exists between the two surfaces (25, 26).

17. The outer part (9) of the upward tongue (4) an upper outer portion (35) defining an outer vertical surface (37) dividing the upward tongue (4) into an inner section on the side of the upward flank (5) and an outer section including the first locking element (28); 17. A panel (1) according to any one of the preceding claims, wherein the maximum width of the inner section is at least 8 times the maximum width of the outer section.

18. the panel includes at least one third connector and at least one fourth connector, each disposed on a pair of opposite sides of the panel (1); A panel (1) according to any one of the preceding claims, wherein the third connection of the panel and the fourth connection of the other panel (1) are arranged to connect by an angular downward movement.

19. The third connecting portion is - lateral tongues extending in a direction substantially parallel to the upper side of the core; at least one second downward flank provided at a distance from said lateral tongue; a second downward groove formed between said lateral tongue and said second downward flank, The fourth connecting portion is a third groove configured to receive at least a portion of a lateral tongue of a third connecting profile of an adjacent panel, the third groove being defined by an upper lip and a lower lip, the lower lip being provided with an upwardly directed locking element; the third connecting portion and the fourth connecting portion are configured so that the two panels can be connected to each other by rotational movement; 19. A panel (1) according to claim 18, wherein in the coupled state, at least a portion of the lateral tongue of the first panel is inserted into the third groove of the adjacent second panel, and at least a portion of the upward locking element of the second panel is inserted into the second downward groove of the first panel.

20. The panel (1) is a decorative panel, at least one core layer, - at least one decorative cap attached directly or indirectly to said core layer, said cap defining the top surface of said panel; A panel (1) according to any one of the preceding claims, comprising a plurality of side edges at least partially defined by the core layer and / or side apexes, at least two opposing side edges being provided with the first connecting portion and the second connecting portion, respectively.

21. A covering comprising a plurality of interconnected panels (1) according to any one of claims 1 to 20.

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