Thermoplastic-based building panel comprising balancing layer

Abstract

The present disclosure relates to a building panel (1) based on thermoplastic, such as a floor panel. The building panel comprises an upper layer arrangement (2), a lower layer arrangement (3) and a balancing layer (4) arranged between the lower layer arrangement and the upper layer arrangement. The building panel further comprises a groove arrangement (10) comprising a groove (11). Furthermore, the present disclosure relates to a building panel (1) based on thermoplastic, comprising an upper layer arrangement and a balancing layer as a bottom layer of the building panel. The building panel includes a trench arrangement in which a major portion of the trench is disposed only in the balancing layer. Finally, the present disclosure relates to a thermoplastic-based building panel (1) comprising a mechanical locking system for horizontally and / or vertically locking a building panel to an adjacent building panel. The mechanical locking system includes a mating surface located in the balancing layer and configured to mate with a mating surface of an adjacent building panel.

Description

[0001] This application is a divisional application of the invention patent application with application date of December 22, 2020, application number 202080088981.3, and invention name “Building panels based on thermoplastics including a balancing layer”. Technical Field

[0002] The present disclosure generally relates to balancing of thermoplastic based building panels, such as floor panels. More specifically, the present disclosure relates to thermoplastic based building panels comprising a balancing layer, wherein the balancing layer is arranged between a lower layer arrangement structure and an upper layer arrangement structure, or wherein the balancing layer is a bottom layer of the building panel. The present disclosure also relates to a thermoplastic based building panel, the building panel comprising a mechanical locking system for horizontal locking and / or vertical locking, the mechanical locking system comprising a cooperating surface at least partially located in the balancing layer. Optionally, the building panel may include at least one groove. Background Art

[0003] Panels comprising thermoplastic materials, such as luxury vinyl tiles (LVT panels) or stone plastic (polymer) composite panels (SPC panels) present many advantages, such as high durability and easy maintenance. However, a typical problem with these types of panels is that they can become too heavy for certain applications. Heavy panels can have a negative impact on their performance as well as on their production and transportation costs. Furthermore, transportation and handling of the panels can become cumbersome. Therefore, there is currently a strong desire to reduce the weight of the panels, for example by using less material during the manufacturing process of the panels, or by removing material from the panels after they are formed. Less material usage also means substantial cost savings.

[0004] WO 2013 / 032391 and WO 2014 / 007738 disclose panels comprising thermoplastic material and provided with a specific groove configuration to reduce the weight thereof. Figure 1a A similar panel comprising specific grooves 10 in the rear side 5 of the panel 1 is shown in the cross-sectional side view of FIG.

[0005] LVT panels or SPC panels usually have a layered construction, each layer performing a different function. For example, a panel may have a wear layer, a printed film and a core. The bottom layer of the panel may be a balancing layer or backing layer, which may ensure that the panel remains sufficiently flat under ambient temperature variations. Typically, the balancing layer mainly comprises thermoplastic material and fillers. However, the above-mentioned grooves usually have a negative impact on the balance of the known panels, which may in fact become dimensionally unstable under ambient temperature variations. At least for some panels, a balancing layer completely penetrated by the grooves may not be sufficient to contribute to the balance of the panel. As Figure 1bAs shown, an unbalanced panel 1 may curl, for example so that the front and back sides become concave. It is generally desirable that the layers of a panel, such as the top layer, core layer and balancing layer, expand and contract in a substantially similar manner so that the panel remains sufficiently flat under temperature changes. Summary of the invention

[0006] It is therefore an object of at least embodiments of the present disclosure to provide a thermoplastic based building panel, such as a floor panel, having a reduced weight and / or a reduced material content and having improved balanced properties.

[0007] It is another object of at least embodiments of the present disclosure to provide a thermoplastic based building panel that is more resistant to curling effects that may be caused by ambient temperature variations, and / or more resistant to indentation effects.

[0008] It is another object of at least embodiments of the present disclosure to provide a stronger and / or more secure mechanical locking system for thermoplastic based building panels.

[0009] At least some of these and other objects and advantages as may be apparent from the description have been achieved through the aspects described below.

[0010] According to a first aspect of the present disclosure, there is provided a thermoplastic based building panel, such as a floor panel, comprising an upper layer arrangement structure comprising at least one upper layer, a lower layer arrangement structure comprising at least one lower layer, and a balancing layer arranged between the lower layer arrangement structure and the upper layer arrangement structure. The building panel further comprises a groove arrangement structure comprising at least one groove, preferably a plurality of grooves.

[0011] By displacing the balancing layer from the back side of the building panel, less material or even no material can be removed from the balancing layer when a groove is provided in the building panel (e.g. at its bottom). As a result, the balancing layer can remain more intact and the balance of the building panel can be improved. In addition, the curling effect of the building panel can be reduced. Generally, in the present disclosure, in particular for the first aspect and the second aspect introduced below, the curling and / or balance of the panel can be determined by ISO 23999:2018 and / or by utilizing the indicator method described in detail in the "Examples" section below. Panels based on thermoplastics can be fully balanced at temperatures up to 60°C or even up to 80°C. Another advantage of a more complete layer assembly is that the panel can become more resistant to the sag effect. Generally, in the present disclosure, in particular for the first aspect and the second aspect, the residual sag / compression resistance can be determined by standard ASTM F1914-18 (ASTM F1700 product specification).

[0012] The building panels, or simply panels, may be floor panels, wall panels, ceiling panels or furniture panels. In non-limiting examples, the floor panels may be LVT tiles, SPC panels, EPC panels (expanded polymer core) or WPC (wood plastic composite) panels. Furthermore, the panels may include a pair of opposing edge portions, such as a first pair and a second pair of opposing edge portions. The first pair and the second pair may include a long edge portion and a short edge portion of the panel, respectively.

[0013] The panel may comprise a front side and a rear side and may extend in a first horizontal direction X and a second horizontal direction Y, which are preferably perpendicular to each other. In a first example, the first horizontal direction and the second horizontal direction extend parallel to the long edge portion and the short edge portion, respectively. In a second example, the first horizontal direction and the second horizontal direction extend parallel to the short edge portion and the long edge portion, respectively. The vertical direction Z of the panel may be perpendicular to the first horizontal direction and the second horizontal direction and may be parallel to the thickness direction of the panel. Thus, we may refer to elements that are arranged "above" or "below" each other. The front side may be adapted to be visible, and at least in some embodiments, for example for floor panels, the rear side may be adapted to be hidden in the installed state of the panel. In practice, a set of building panels, such as floor panels, may be installed on an underlying structure, such as a subfloor.

[0014] The at least one groove may have a longitudinal extension and a transverse extension. The longitudinal extension may be larger than the transverse extension. In a first example, the longitudinal extension and the transverse extension may be parallel to the long edge portion and the short edge portion, respectively. In a second example, the longitudinal extension and the transverse extension may be parallel to the short edge portion and the long edge portion, respectively.

[0015] The upper layers may be laminated to each other and / or bonded to each other by an adhesive. Similarly, the lower layers may be laminated to each other and / or bonded to each other by an adhesive. The upper layer arrangement and / or the lower layer arrangement may be laminated to the balancing layer and / or bonded to the balancing layer by an adhesive. Any of the layers or layer arrangements herein may be laminated to each other under heat and pressure. In the second aspect described below, reference will typically be made only to the upper layer arrangement without reference to the lower layer arrangement.

[0016] The trench arrangement may be provided in the underlying arrangement.

[0017] At least one groove may be provided on the rear side of the underlying arrangement, preferably on the bottom layer thereof.

[0018] The groove arrangement may be "post-formed" after forming the panel itself, preferably by removing material from an underlying layer, e.g. a lower layer, of the panel. A person skilled in the art will appreciate that within the scope of the present invention the concept of "post-forming" includes the case where the groove arrangement is post-formed after forming the sheet itself and subsequently dividing the sheet into at least one panel, e.g. a plurality of panels. Prefabricated grooves are likewise possible.

[0019] The at least one groove may taper towards a depth direction of the groove, which depth direction may be parallel to a vertical direction of the panel. Typically, an inner portion of the groove may be curved or planar.

[0020] In some embodiments, each of the at least one groove may be an internal groove arranged in the underlying arrangement structure, for example in its bottom layer. Thus, the internal groove may have walls along one horizontal direction and along a vertical direction inside the panel. The internal groove may be open towards another horizontal direction.

[0021] The groove depth, preferably the maximum groove depth, of at least one groove may be more than 20%, for example more than 30% or more than 40% of the thickness of the underlying structure and / or of the thickness of the building panels, e.g. floor panels.

[0022] Generally, the balancing layer may be at least partially disposed over the trench arrangement structure, for example completely disposed over the trench arrangement structure.

[0023] The main part of the groove may be completely arranged below the balancing layer. Therefore, the main part of the groove does not extend into (eg penetrate) the balancing layer. For example, the groove may only penetrate the underlying arrangement structure.

[0024] Generally, in this context, a major part of the trenches may comprise a major part of the total volume of the trenches and / or a major part of the total number of trenches. Thus, a major part of the total volume of the trenches and / or a major part of the total number of trenches may be completely disposed below the balancing layer.

[0025] The major part may be at least 50% of the number of grooves and / or at least 50% of the total volume of the grooves. When the grooves are arranged at the rear side, the total volume of the grooves may be the volume occupied by the grooves in the panel and limited by the horizontal plane HP arranged along the rear side. When the grooves are internal grooves, the total volume of the grooves may be the volume occupied by the grooves in the panel and limited by the vertical plane VP preferably arranged along the edge portion.

[0026] In some embodiments, the average groove depth of the plurality of grooves may be less than the thickness of the underlying arrangement structure. Therefore, the average value of the innermost portion of the grooves along the vertical direction may be disposed below the balancing layer. These embodiments provide examples in which the main portion of the grooves is completely disposed below the balancing layer.

[0027] In some embodiments, all trenches are disposed completely below the balance layer.

[0028] The building panel may comprise a plurality of grooves in the lower arrangement, wherein the innermost portion of at least one groove is spaced a distance from the balancing layer in the vertical direction of the building panel. Thus, the lower arrangement may be continuous, which may improve the balancing of the panel. For example, there may be a distance between each of the plurality of grooves and the balancing layer. The distance may be at least 0.3 mm, such as at least 1 mm. Preferably, the distance is non-negative, although in alternative embodiments the distance between the groove and the balancing layer is negative, such that the groove extends through the balancing layer. The distance may be greater than 0.25 times the thickness of the uppermost layer of the upper arrangement, preferably greater than 0.50 times or 1.0 times the thickness of the uppermost layer. For example, the uppermost layer may be a wear resistant layer.

[0029] The combined thickness, such as the maximum combined thickness, of the underlying arrangement structure and the balancing layer may be at least 20%, such as at least 35% or at least 50% of the thickness of the building panel.

[0030] The thickness of the balancing layer may be smaller than the trench depth of at least one trench, preferably smaller than the maximum trench depth thereof.

[0031] Generally, in the present context, the maximum groove depth of a groove may be the distance from the back side of the building panel to the innermost part of the groove. The groove depth may be the distance along the vertical direction of the building panel. Furthermore, for an internal groove, the maximum groove depth may be the maximum vertical distance between the walls of the internal groove.

[0032] The thickness, eg the maximum thickness, of the balancing layer may be at least 5%, such as at least 10% or at least 20% of the thickness of the building panel. In some embodiments the thickness of the balancing layer may even be at least 30% of the thickness of the building panel.

[0033] The thickness, e.g. maximum thickness, of the balancing layer may be greater than the thickness of an upper layer of the superstructure, wherein the upper layer is preferably the uppermost layer of the superstructure. For example, the uppermost layer may be a wear-resistant layer. Thus, an improved balance of the panel may be provided. The thickness, e.g. maximum thickness, of the balancing layer may be at least the same as, preferably greater than, the thickness of the uppermost layer. In some embodiments, the thickness (e.g. maximum thickness) of the balancing layer may be at least 5 times or at least 10 times the thickness (e.g. maximum thickness) of the uppermost layer (e.g. wear-resistant layer).

[0034] According to a second aspect of the disclosure, there is provided a thermoplastic based building panel, such as a floor panel, comprising an upper layer arrangement comprising at least one upper layer and a balancing layer being a bottom layer of the building panel. The building panel further comprises a groove arrangement comprising at least one groove, preferably a plurality of grooves, wherein a major part of the grooves are provided only in the balancing layer.

[0035] According to the second aspect, a major part of the groove does not penetrate into other layers of the building panel and the balancing layer can remain more intact. Thus, an improved balancing of the panel may be provided. Furthermore, curling effects of the building panel, such as caused by ambient temperature changes, may be reduced. Incidentally, it should be noted that a minor part of the groove may optionally penetrate into an upper layer of the building panel.

[0036] Generally, in this context, the minor portion and the major portion may correspond collectively to all grooves, such as the total number of grooves and / or the total volume of the grooves.

[0037] The upper layers may be laminated to each other and / or bonded to each other by an adhesive.The upper layer arrangement may be laminated to the balancing layer and / or bonded to the balancing layer by an adhesive.

[0038] In some embodiments, all grooves are disposed only in the balancing layer. Thus, the bottom layer may be continuous without any grooves penetrating its lower and upper sides.

[0039] The groove depth of the groove or grooves, preferably the maximum groove depth, may be more than 20%, such as more than 30% or more than 40% of the balancing layer thickness and / or the building panel (eg floor panel) thickness.

[0040] In some embodiments, the average groove depth of the plurality of grooves may be less than the thickness of the balancing layer. Therefore, the average value of the innermost portion of the grooves along the vertical direction may be disposed below the upper arrangement structure. These embodiments provide examples in which the main portion of the grooves is completely disposed below the upper arrangement structure.

[0041] The groove may be provided on the rear side of the balancing layer.

[0042] In some embodiments, each of the at least one groove may be an internal groove at least partially, preferably completely, arranged in the balancing layer. Thus, the internal groove may have walls in the panel along one horizontal direction and a vertical direction of the panel. The internal groove may be open towards another horizontal direction.

[0043] The major portion may comprise a major portion of the total volume of the grooves and / or a major portion of the total number of grooves. In some embodiments, the major portion of the grooves may comprise a major portion of the groove depth. Thus, a major portion, such as at least 50%, of the innermost portion of the grooves may be completely disposed below the balancing layer.

[0044] The major portion may be at least 50% of the number of grooves and / or at least 50% of the total volume of the grooves. In some embodiments, the total volume of the grooves may be at least 60% or even at least 70% of the total volume of the grooves. An embodiment of the total volume of the grooves has been described with respect to the first aspect, whereby reference is made to it by analogy. The major portion of the total number of grooves may exceed 50% of the total number of grooves. In a non-limiting example, the major portion of 11 grooves is at least 6 grooves, and the major portion of 14 grooves is at least 8 grooves. By analogy, the embodiments relating to the "major portion" also apply to the first aspect.

[0045] The thickness, e.g., maximum thickness, of the balancing layer may be greater than the thickness of an upper layer of the superstructure, wherein the upper layer is preferably the uppermost layer of the superstructure. For example, the uppermost layer may be a wear-resistant layer. The thickness (e.g., maximum thickness) of the balancing layer may be at least 4 times, e.g., at least 10 times, or at least 20 times, of the thickness (e.g., maximum thickness) of the uppermost layer (e.g., wear-resistant layer).

[0046] The thickness, e.g. the maximum thickness, of the balancing layer may be at least 20%, e.g. at least 35% or at least 50% of the thickness of the building panel. Such a relatively thick balancing layer may require more material content and may become more expensive. However, by using recyclable materials, e.g. thermoplastic polymers, in the balancing layer, the material removed or saved when forming the grooves may be recycled or reused. Thus, costs, e.g. the total production cost of several panels, may be effectively reduced.

[0047] The building panel may comprise a plurality of grooves in the balancing layer, wherein the innermost part of at least one groove is spaced a distance from the superposition structure in the vertical direction of the building panel. Thus, the balancing layer may be continuous, which may improve the balancing of the panel. For example, each of the plurality of grooves may be separated from the superposition structure. The distance may be at least 0.3 mm, such as at least 1 mm. The distance may be greater than 0.25 times the thickness of the uppermost layer of the superposition structure, preferably greater than 0.50 times or 1.0 times the thickness of the uppermost layer. For example, the uppermost layer may be a wear resistant layer.

[0048] It is emphasized that for the panel according to either of the first and second aspects, the following embodiments are conceivable.

[0049] In some embodiments, the trench depths of the plurality of trenches may be substantially the same.

[0050] The building panels may comprise a plurality of grooves, wherein the groove depth, preferably the maximum groove depth, of at least two grooves is different.

[0051] In some embodiments, the groove arrangement may include calibration grooves, such as described in WO 2014 / 182215, page 2, lines 13-22, which is incorporated herein by reference in its entirety.

[0052] Typically, the balancing layer may be a discontinuous layer. Thus, the balancing layer may be completely penetrated, for example by at least one groove or even all grooves. Such a panel may be less balanced than a panel in which the balancing layer is continuous, but may be sufficiently balanced for some applications. Optionally, in such an embodiment, the panel may include a reinforcing element, see discussion below.

[0053] The balancing layer may be a continuous layer. According to this embodiment, the balancing layer is not completely penetrated, for example by grooves. Thus, the panel may become more balanced. In a first example, the balancing layer has a substantially constant thickness, optionally comprising internal grooves. In a second example, the balancing layer has a varying thickness along a first horizontal direction and / or a second horizontal direction of the building panel. The varying thickness may be generated by grooves at least partially provided in the balancing layer.

[0054] The building panel may include at least one reinforcing element, such as at least one fiberglass layer. The upper arrangement and / or the lower arrangement may include a reinforcing element, such as a fiberglass layer. Furthermore, the balancing layer may include a reinforcing element, such as a fiberglass layer. In some embodiments, the reinforcing element may contribute to the balancing of the panel.

[0055] The at least one reinforcing element may be arranged in a central part of the building panel, wherein the central part is arranged between an innermost part of the groove and a front side of the panel in a vertical direction. The central part may be arranged at a distance from the front side that is between 35% and 65% of the distance between the innermost part and the front side.

[0056] Building panels such as floor panels may also comprise a mechanical locking system in one or more edge portions for locking the building panel horizontally and / or vertically to adjacent one or more building panels.The panels may comprise a mechanical locking system on long edge portions and / or short edge portions.

[0057] In some embodiments, the building panels are not provided with any mechanical locking system. Instead, the panel may be implemented as a floor panel that may be configured to be loosely installed on a subfloor, or it may be implemented as a building panel, such as a floor panel, that is configured to be nailed or glued to an underlying structure such as a subfloor.

[0058] Embodiments of the mechanical locking system of the first aspect or the second aspect may be implemented according to any embodiment described herein with respect to the third aspect.

[0059] Typically, in this context, the panel thickness may be 2-40 mm, such as 2-10 mm or 3-6 mm. For example, when the thickness of the underlying arrangement in the first aspect or the balancing layer in the second aspect is 2-30 mm, the groove depth of any groove may be at least 0.5-10 mm. For example, a floor panel with a thickness of 2-10 mm may have a groove depth of at least 0.5-5 mm.

[0060] Note that in either of the first and second aspects, a separately formed bottom layer element may at least partially, preferably completely, cover the back side of the panel. The bottom layer element may be a foam, such as radiation cross-linked polyethylene foam (IXPE) or ethylene vinyl acetate foam (EVA), or a cork. The bottom layer element may be bonded to the back side by an adhesive according to principles known in the art.

[0061] According to a third aspect of the present disclosure, there is provided a thermoplastic based building panel, such as a floor panel, comprising an upper and / or lower arrangement structure, a balancing layer comprising a thermoplastic polymer, and a mechanical locking system for horizontally and / or vertically locking the building panel to an adjacent building panel. The mechanical locking system comprises a mating surface which is arranged in an edge portion of the building panel and is configured to mate with a mating surface of an adjacent building panel, wherein the mating surface of the mechanical locking system is at least partially located in the balancing layer.

[0062] For many thermoplastic based panels, a part of the mechanical locking system may be the weakest part of the panel, for example when subjected to high stresses, for example when conducting high load tests, locking strength tests or castor chair tests, or during panel installation. The mechanical locking system according to the third aspect may be made stronger and / or more secure. For example, the risk of damage (e.g. cracking) of a part of the mechanical locking system may be reduced.

[0063] The mating surfaces, such as locking surfaces and / or guide surfaces, may be directly engaged or indirectly engaged. In any embodiment described herein, a sealant, such as wax or adhesive, may be provided between the mating surfaces, thereby providing an example of indirect engagement.

[0064] The mating surface may be a horizontal and / or vertical mating surface for horizontal and / or vertical mating, eg locking to and / or guiding an adjacent panel.

[0065] The balancing layer may be arranged between the lower arrangement structure and the upper arrangement structure.The embodiments and examples may be the same as those of the first aspect, and reference is made thereto.

[0066] The balancing layer may be a bottom layer of the building panels.Embodiments and examples may be identical to those of the second aspect, reference is hereby made to them.

[0067] The balancing layer may extend at least partially through locking elements provided on the strip and / or through locking grooves, wherein the locking elements are configured to engage with locking grooves of adjacent building panels for horizontal locking. The strip may extend horizontally beyond the upper edges of the edge portions. Typically, in a locked state of the panels, the upper edges of the panels may be juxtaposed. When the normal of the surface portion of the upper edge is arranged perpendicular to the normal of the front and / or back side of the panel, they may define a vertical plane VP, which preferably has a normal parallel to the normal of the surface portion.

[0068] The balancing layer may extend at least partially through an upper portion, an inner wall and / or an outer wall of the locking element and / or through an upper wall, an inner wall and / or an outer wall of the locking groove,

[0069] Generally in this context, an edge portion may be a short edge portion and / or a long edge portion.

[0070] The mating surface may be located on the locking element and / or in a locking groove, for example at least partially in the balancing layer.

[0071] An uppermost surface of the locking element may comprise a portion of the balancing layer, wherein the mating surface is preferably arranged in the uppermost surface.

[0072] The balancing layer may extend at least partially along the strip, for example along an upper portion of the strip.The strip may be embodied as described above.

[0073] For example, the uppermost surface of the strip arranged horizontally inside the locking element may comprise a portion of the balancing layer. The mating surface may be arranged in the uppermost surface.

[0074] The transition surface from the uppermost surface of the strip to the locking element, e.g. the inner wall of the locking element, may comprise a portion of the balancing layer. Thus, the mechanical locking system may become more secure and / or more robust, e.g. when subjected to high stresses, e.g. when performing a locking strength test, or during panel installation. In practice, the area around the transition surface, in particular on the short edge portions, may be exposed to particularly high stresses. Alternatively, the transition surface may comprise a portion of the uppermost surface of the strip and / or a portion of the inner wall of the locking element.

[0075] The balancing layer may extend at least partially through the tongue portion, for example through a lower part of the tongue portion, wherein the tongue portion is configured to engage with a tongue groove of an adjacent building panel for vertical locking.

[0076] The tongue part may comprise a tongue formed integrally with the panel.

[0077] The tongue part may comprise a separate, preferably flexible tongue, which is configured to be arranged in a displacement groove provided at an edge portion, preferably a short edge portion, of the panel.

[0078] The mating surface may be at least partially provided in a wall of the tenon tongue groove, for example in at least one of an upper wall, a lower wall and an inner wall of the tenon tongue groove.

[0079] The mating surface may be located on the tongue portion.

[0080] The lowermost surface of the tongue portion may comprise a part of the balancing layer, wherein the mating surface is preferably provided in the lowermost surface.

[0081] The mating surface may be a first mating surface arranged in a first edge portion of the building panel, and the mechanical locking system may further include a second mating surface arranged in a second edge portion of the building panel, the first edge portion and the second edge portion being preferably arranged oppositely on the building panel, wherein the second mating surface is at least partially located in the balancing layer.

[0082] Typically, the first mating surface and the second mating surface may be arranged to mate with corresponding second mating surfaces and first mating surfaces of respective adjacent building panels. The mating surfaces of adjacent building panels may be general mating surfaces. However, alternatively, the mating surfaces of adjacent building panels may be located at least partially in a balancing layer of an adjacent building panel.

[0083] The mating surface may be a locking surface which is configured to engage with a locking surface of an adjacent building panel in a locked state of the building panel and the adjacent building panel. The locking surface may engage for vertical locking and / or horizontal locking. Thus, the locking surface may be a vertical locking surface and / or a horizontal locking surface. The locking surface of the adjacent building panel may be a general locking surface. However, optionally, the locking surface of the adjacent building panel may be located at least partially in a balancing layer of the adjacent building panel.

[0084] The mating surface may be a guiding surface configured to guide an adjacent building panel during locking of the building panel to the adjacent building panel, for example by mating or engaging with a mating surface (e.g. guiding surface) of the adjacent building panel during the locking process. The guiding surface may guide the adjacent panel vertically and / or horizontally. The mating surface (e.g. guiding surface) of the adjacent building panel may be a general mating surface. However, optionally, the mating surface of the adjacent building panel may be located at least partially in a balancing layer of the adjacent building panel.

[0085] The adjacent building panels can be configured to be angled / tilted downward during locking and / or displaced vertically downward toward the building panels. However, alternatively, the building panels can be configured to be angled / tilted downward during locking and / or displaced vertically downward toward the adjacent building panels. In fact, it will be understood by a person of ordinary skill that within the scope of the present disclosure, the roles of the building panels and adjacent building panels described herein can be interchanged. For example, the features of mating surfaces, such as locking surfaces and / or guide surfaces can be interchanged. In particular, the adjacent building panels may include a mechanical locking system for locking the adjacent building panels horizontally and / or vertically to the building panels, the mechanical locking system including a mating surface, which is disposed in an edge portion of the adjacent building panel and is configured to mate with a mating surface of the building panel. The mating surface may be at least partially located in a balancing layer of the adjacent building panel. However, for simplicity, only the mating surface at least partially located in the balancing layer of the building panel is generally mentioned / referenced.

[0086] In some embodiments, the mating surface may be a locking surface as well as a guiding surface.

[0087] The building panels may further comprise a groove arrangement comprising at least one groove, preferably a plurality of grooves.The groove may be implemented as any of the first aspect or the second aspect, reference is hereby made thereto.

[0088] When the panel is subjected to high stress and / or severe curling, the inner part of the groove may be the weakest part of the panel. By having a layer including a thermoplastic polymer, such as a lower layer or a balancing layer, the inner part can be more flexible and / or less brittle. As a result, the inner part and therefore the entire panel can become more resistant to high stress.

[0089] Further embodiments and examples of the building panels according to the third aspect may be largely similar to those of the first or second aspect, reference being hereby made to the above. In particular, embodiments and examples of at least one selected from the group consisting of the groove, the upper arrangement and / or the lower arrangement, the balancing layer and the thickness may be identical. However, it is emphasized that for the building panels according to the third aspect the groove arrangement is optional.

[0090] It is emphasized that the following embodiments concerning the material composition and properties of the balancing layer and the upper and / or lower arrangement structures are applicable to each of the first, second and third aspects.

[0091] The upper layer arrangement, for example each of the at least one upper layer, may comprise a thermoplastic polymer and optionally a filler.

[0092] The upper arrangement may include a wear layer and / or a printed layer, such as a printed film. Preferably, the wear layer is the uppermost layer. The printed layer may be disposed below the wear layer. It should be understood that, in general, a coating such as a UV curable coating, preferably a wear layer, may be provided on the upper arrangement, such as on the uppermost layer. For clarity, such coatings are often omitted in the present disclosure, but may be understood to be implicitly included.

[0093] The balancing layer may comprise a thermoplastic polymer and optionally a filler.

[0094] The underlying arrangement, for example each of the at least one underlying layer, may comprise a thermoplastic polymer and optionally a filler.

[0095] The thermoplastic polymer of the upper and / or lower layers may include polyvinyl chloride (PVC), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), acrylonitrile butadiene styrene (ABS) or thermoplastic polyurethane (TPU). Additionally or alternatively, the balancing layer may include PVC, PE, PET, PP, ABS or TPU. For example, the amount of thermoplastic polymer in each upper and / or lower layer and / or balancing layer may be 10-70 wt%, such as 20-50 wt%.

[0096] Typically, the filler of the upper arrangement structure and / or the lower arrangement structure and / or the balancing layer may include an organic filler and / or an inorganic filler. The filler may be a functional filler and / or an extender. The inorganic filler may be a mineral material, such as calcium carbonate (CaCO 3 ) or stone, such as stone powder or similar materials. The organic filler can be organic fiber, such as wood chips or rice husks. The filler can also be a clay material, such as kaolin. For example, the amount of filler in each upper layer and / or lower layer and / or balancing layer can be 20-90wt%, such as 40-80wt%.

[0097] Optionally, any one, any pair or each of the upper layer arrangement structure, the lower layer arrangement structure and the balancing layer can contain a plasticizer and / or an additive, such as a stabilizer, an impact modifier, a pigment or a lubricant. However, optionally, the upper layer arrangement structure and / or the lower layer arrangement structure can include a foaming agent. Typically, the panel can be an elastic panel or a rigid panel, such as due to including a plasticizer and not including any plasticizer, respectively. Similarly, for example, depending on the presence of a plasticizer, the upper layer or the lower layer or the balancing layer can be elastic or rigid. In a preferred embodiment, the balancing layer can be elastic, thereby including a plasticizer. Therefore, the balancing performance of the panel can be enhanced.

[0098] Generally, in this document, the concept of "material composition" may include at least one of the amount and type of thermoplastic polymer, the amount and type of filler, the amount and type of plasticizer and / or additive, and the like.

[0099] At least two layers of the panel, for example at least one upper layer and / or at least one lower layer, may have the same material composition.

[0100] In some embodiments, the upper layer and the balancing layer and the lower layer in the first aspect may include different material compositions. For example, each of the upper layer, the balancing layer and the lower layer in the first aspect may include a thermoplastic polymer, and preferably includes a filler.

[0101] In some embodiments of the first aspect, the upper layer and the lower layer may include substantially similar material compositions. For example, the upper layer and the lower layer may include a thermoplastic polymer and preferably a filler.

[0102] In some embodiments of the first aspect and the second aspect, the upper layer and the balancing layer may include substantially similar material compositions. For example, the upper layer and the balancing layer may include thermoplastic polymers, and preferably include fillers.

[0103] The amount of thermoplastic polymer in the balancing layer can be higher than the amount of thermoplastic polymer in the upper and / or lower arrangement structures. For example, the amount can be specified in weight percentage or volume percentage, or, for example, when the thermoplastic polymer is PVC, in parts per hundred of PVC resin / percentage of PVC resin (PHR). Optionally, the amount of filler, such as mineral filler, in the balancing layer can be lower than the amount of filler in the upper and / or lower arrangement structures. With this embodiment, the balancing layer can become less fragile and / or more flexible. In addition, the strength of the balancing layer, such as tensile strength, can become higher. This may be advantageous, for example, when the mating surface is at least partially located in the balancing layer according to the third aspect. For example, the mechanical locking system can become even more secure and / or stronger. Note that a lower degree of filler, especially mineral filler, in the layer can make the layer less fragile.

[0104] The amount of thermoplastic polymer in the balancing layer can be higher than the amount of thermoplastic polymer in each of the upper and / or lower layers. Generally, in this article, the panel can include an upper layer arrangement structure and a lower layer arrangement structure (first aspect), an upper layer arrangement structure (second aspect), or any combination of an upper layer arrangement structure and / or a lower layer arrangement structure (third aspect). Optionally, the amount of filler such as a mineral filler in the balancing layer can be lower than the amount of filler in each of the upper and / or lower layers.

[0105] Typically, the first layer of the panel, e.g. the wear layer or the balancing layer, comprises a higher content of thermoplastic polymer and optionally a lower content of filler than the second layer of the panel, which may be more conducive to curling of the panel, e.g. because thermoplastic polymers such as PVC and fillers such as CaCO 3 For example, the first layer may be a balancing layer or a wear layer, and the second layer may be an upper layer or a lower layer.

[0106] At least one upper layer and / or lower layer of the building panel may be extruded, such as coextruded.Preferably, each extruded or coextruded layer comprises a thermoplastic polymer.

[0107] The balancing layer itself may be extruded, or it may be coextruded with at least one upper layer and / or lower layer. For example, the panel may comprise an AB, ABA or ABC coextruded layer element comprising two or three layers. The balancing layer may be disposed between an upper layer and a lower layer in an ABA or ABC coextruded layer element. Here, the same letter (A) and different letters (A, B or C) refer to layers having substantially the same material composition and layers having different material compositions, respectively.

[0108] In some embodiments, the upper and / or lower arrangement may comprise a non-polymer layer. In a first example, the veneer / veneer may be bonded to the upper layer, which is preferably a layer comprising a thermoplastic polymer and preferably comprising a filler. In a second example, paper, preferably melamine-formaldehyde impregnated paper may be bonded to the upper layer, which is preferably a layer comprising a thermoplastic polymer and preferably comprising a filler.

[0109] According to a fourth aspect of the present disclosure, a panel assembly comprising a building panel and an adjacent building panel is provided. The building panel and / or the adjacent building panel may be implemented as a building panel according to any embodiment and example of the first, second and third aspects, to which reference is hereby made.

[0110] Embodiments and examples of other aspects of the present disclosure and each of the first, second, third and fourth aspects are provided in the following illustrative embodiments section. It should be emphasized that the embodiments and examples of any aspect can be combined with the embodiments and examples of any other aspect.

[0111] Unless otherwise expressly defined herein, generally all terms used in the claims and clauses are to be interpreted according to their ordinary meaning in the technical field. Unless otherwise expressly stated, all references to "an / the [element, device, component, method, step, etc.]" should be openly interpreted as referring to at least one instance of the element, device, component, method, step, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] The present disclosure will be described below in conjunction with exemplary embodiments and will be described in more detail with reference to the accompanying exemplary drawings, in which:

[0113] Figure 1a-1b An embodiment of a floor panel comprising grooves and an embodiment of a rolled floor panel according to known technology are shown in a cross-sectional side view.

[0114] Figure 1c-1e In perspective ( Figure 1c )、Bottom view( Figure 1d ) and sectional side view ( Figure 1e ) show an exemplary embodiment of a building panel according to the first aspect.

[0115] Figure 2a-2d A cross-sectional side view of an exemplary embodiment of a building panel according to the first aspect is shown.

[0116] Figure 3a-3c Cutaway side view ( Figure 3a-3b ) and bottom view ( Figure 3c ) show an exemplary embodiment of a building panel according to the second aspect.

[0117] Figure 4a-4c A cross-sectional side view of an exemplary embodiment of a building panel according to the second aspect is shown.

[0118] Figure 5a-5d Cutaway side view ( Figure 5a-5b ) and perspective view ( Figure 5c ) shows an exemplary embodiment of a building panel according to the first and second aspects, and an embodiment of an underlying arrangement is shown in a sectional side view ( Figure 5d ).

[0119] Figure 6a-6c From the bottom view ( Figure 6a )、Cross-sectional top view( Figure 6c ) and sectional side view ( Figure 6b-6c ) shows an exemplary embodiment of a building panel comprising a mechanical locking system.

[0120] Figures 7a-7f Exemplary embodiments comprising a mechanical locking system and building panels and locking of the building panels are shown in a sectional side view and in an enlarged sectional side view.

[0121] Figures 8a-8d A cross-sectional side view of an exemplary embodiment of building panels comprising a mechanical locking system is shown.

[0122] Figure 9a-9bA cross-sectional side view of an exemplary embodiment of building panels comprising a mechanical locking system and their locking is shown.

[0123] Figure 9c-9e An exemplary indicator device is shown that may implement the indicator method described herein.

[0124] Figure 10a-10c A photograph of an exemplary reference panel sample and a photograph of an exemplary panel sample according to the first aspect are shown, illustrating the curling effect under certain temperature variations.

[0125] Fig.10d A photograph of an exemplary reference panel sample is shown.

[0126] Figures 11a-11d Shown are photographs of exemplary panel samples according to the first and second aspects showing the curling effect and photographs of exemplary reference panel samples.

[0127] Figures 12a-12d A photograph of an exemplary panel sample according to the first aspect subjected to a residual sag test is shown. DETAILED DESCRIPTION

[0128] Various aspects of the present disclosure will be described below with respect to thermoplastic-based floor panels, but a person skilled in the art will appreciate that within the scope of the present disclosure they are applicable to general building panels, such as wall panels, ceiling panels or furniture panels. Therefore, in the following, reference will often be made simply to the panels.

[0129] Figure 1c-1e , Figure 2a-2d , Figure 5a , Figure 5c , Figure 6a-6c , Figure 7a-7c , Figure 8a-8b , Figure 8d and Figure 9a An embodiment of a thermoplastic-based panel 1 in the form of a floor panel according to the first aspect is shown. The panel comprises an upper layer arrangement 2, a lower layer arrangement 3 and a balancing layer 4 arranged between the lower layer arrangement and the upper layer arrangement. Typically, the upper layer arrangement comprises at least one upper layer 2a, 2b, 2c and the lower layer arrangement comprises at least one lower layer 3a, 3b. A groove arrangement 10 comprising at least one groove 11, preferably a plurality of grooves, is arranged in the lower layer arrangement 3.

[0130] The upper arrangement 2 may comprise a wear resistant layer and / or a printed layer. The wear resistant layer may be the uppermost layer 2a.

[0131] In some embodiments, the upper layer arrangement structure 2 and / or the lower layer arrangement structure 3 can be laminated to the balancing layer 4. In turn, at least some of the upper layers and / or lower layers can be laminated to each other. For example, the upper layer, the lower layer and the balancing layer can be provided as sheets, or can be provided from a rolling mill and can be laminated to each other under heat and pressure. These sheets can be stacked layer by layer and can be laminated to each other, for example, in a hot press or a multi-layer static press. The layers provided from the rolling mill can be laminated to each other in a continuous process. In some embodiments, the balancing layer can be (co)extruded with at least one upper layer and / or lower layer, for example all upper layers and lower layers except the wear-resistant layer and / or the printing layer.

[0132] For example Figure 1c-1e , Figure 2a-2d , Figure 6a-6c and Figure 7a As shown in the embodiment in FIG. 1 , the grooves 11 can be provided in the rear side 5 of the underlying arrangement 3, preferably in the bottom layer 5' thereof. The grooves can be post-formed after the panel itself is formed, for example by removing material from the bottom layer 5', for example by rotating a saw blade, cutting, milling, scraping or slicing. Alternatively, the grooves can be pre-formed when the panel is formed, for example during heating and pressing of the panel.

[0133] However, if Figure 5a and Figure 5c As shown in the embodiment in FIG. 5 , it is conceivable that the grooves may be provided in the underlying arrangement, for example in its bottom layer 5 '. In the illustrative embodiment, the grooves are defined by the portion of the panel located below the grooves. Optionally, the grooves may comprise openings at the surface of the panel 1 facing downwards. For example, these internal grooves 11 may be preformed in the underlying arrangement, for example during the manufacture of the underlying arrangement and / or the panel, for example by (co)extrusion. The internal grooves 11 may have a plurality of grooves in the panel along a horizontal direction (for example Figure 5c The wall of the panel is oriented in a second horizontal direction Y) and in a vertical direction Z of the panel. Generally, in this context, the thickness direction may be parallel to the vertical direction Z of the panel. The internal groove may be oriented in another horizontal direction, for example Figure 5c The first horizontal direction shown is open X. Thus, the inner groove can extend all the way to an edge portion, for example a short edge portion.

[0134] The balancing layer 4 may be arranged at least partially above the groove arrangement 10. Thus, the balancing layer may be continuous. Figure 1c , Figure 1e , Figure 2a , Figure 2c-2d , Figure 5a , Figure 5c , Figure 6b-6c and Figure 7aAs also shown in some of these figures, the balancing layer 4 may be arranged entirely above the trench arrangement.

[0135] It is also conceivable that Figure 2b As shown in the embodiment in FIG. 1 , all grooves 11 completely penetrate the balancing layer, so that the balancing layer 4 becomes discontinuous. However, such a panel 1 may be less balanced than a panel in which the balancing layer is at least partially arranged above the groove arrangement. Nevertheless, such a panel may be sufficiently balanced for certain applications. For example, as described below, a reinforcing element 13 may be arranged therein.

[0136] For example Figure 1c , Figure 1e , Figure 2c-2d , Figure 5a , Figure 5c and Figure 6b-6c As shown in the embodiment in , the balancing layer 4 may have a substantially constant thickness T4, preferably by all grooves in the panel being arranged completely below the balancing layer. The grooves may only penetrate the underlying arrangement 3.

[0137] It is also conceivable that the balancing layer 4 may have a thickness T4 that varies along the first horizontal direction X and / or the second horizontal direction Y of the panel. Figure 2a-2b and Figure 7a As shown, the groove 11 may be at least partially disposed in the balancing layer 4, thereby providing a varying thickness along the second horizontal direction Y. A major portion of the groove may be disposed completely below the balancing layer, such as Figure 2a Optionally, the thickness may also vary along the first horizontal direction X, for example by grooves being arranged in the edge portion of the panel along the first horizontal direction X. This is useful, for example Figure 1c-1e , Figure 2a-2d , Figure 6a-6c and Figure 7a-7c Any embodiments are contemplated.

[0138] The major part may be at least 50% of the number of grooves and / or at least 50% of the total volume TV of the grooves. The total volume TV of the grooves 11 arranged in the rear side 5 may be the volume occupied by the grooves in the panel, e.g. defined by the inner walls 11b of the grooves, and limited by a horizontal plane HP arranged along the rear side, see e.g. Figure 6b The total volume TV of the internal groove 11 may be the volume occupied by the groove within the panel, for example defined by the inner wall 11b of the groove, and limited by a vertical plane VP arranged along the edge portion of the internal groove opening, see e.g. Figure 5c .

[0139] Typically, the groove depth GD of the groove 11 can be greater than 20% of the thickness T3 of the underlying arrangement 3, for example greater than 30% of the thickness T3 or even greater than 40% of the thickness T3. In some embodiments, the groove depth GD can be greater than 20% of the panel thickness T1, for example greater than 30% of the thickness T1 or greater than 40% of the thickness T1.

[0140] like Figure 1e , Figure 2c-2d , Figure 5a , Figure 5c , Figure 6b-6c and Figure 7a As shown in the embodiment of FIG. 1 , the innermost portion 11a of one or more of the plurality of grooves 11 may be spaced apart from the balancing layer 4 by a distance Sa in the vertical direction Z of the panel. Figure 2a As shown, for a pair of transverse outermost grooves (but it is obviously conceivable that for any one, some or each groove), the distance Sa may be zero (Sa=0). Optionally, when Sa=0, the balancing layer 4 may be exposed from below. In some embodiments, the distance Sa may be greater than 0.25 times the thickness TU of the uppermost layer 2a (e.g., the wear-resistant layer). However, preferably, the distance is greater than 0.50 times the thickness TU of the uppermost layer 2a or even greater than 1.0 times the thickness TU.

[0141] For example Figure 2a However, it can be applied to any embodiment of the first aspect, for example Figure 1c-1e , Figure 2c-2d , Figure 5a , Figure 5c , Figure 6a-6c and Figure 7a In the embodiment of FIG. 1 , the average trench depth GA of the trench 11 may be less than the thickness T3 . Figure 2a The average depth of the trenches 11 ′ is schematically shown.

[0142] Typically for the first aspect, the thickness T4 of the balancing layer 4 may be at least 5%, such as at least 10% or at least 20% of the panel thickness T1. Alternatively or additionally, the combined thickness T1 of the underlying arrangement 3 and the balancing layer 4 may be at least 20%, such as at least 35% or at least 50% of the panel thickness T1.

[0143] Furthermore, the thickness T4 of the balancing layer may be greater than the thickness TU of the upper layer. For example, the upper layer may be the uppermost layer 2a, such as a wear-resistant layer. Figure 1e Shown in.

[0144] Figure 5d An embodiment of a sublayer arrangement 3 comprising a first sublayer 3a and a second sublayer 3b is shown in a sectional side view. Figure 1c-1e , Figure 2a-2d , Figure 5a , Figure 5c , Figure 6a-6c , Figure 7a-7c Any of the underlying arrangements in may be replaced with this underlying arrangement, preferably having grooves therein.

[0145] Figure 3a-3c , Figure 4a-4c , Figure 5b , Figure 7d-7f , Figure 8c and Figure 9b An embodiment of a thermoplastic based panel 1 in the form of a floor panel according to the second aspect is shown. The panel comprises an upper layer arrangement 2 and a balancing layer 4, which is a bottom layer 5' of the panel. The upper layer arrangement comprises at least one upper layer 2a, 2b, 2c, 2d. A groove arrangement 10 comprising a plurality of grooves 11 is provided in the balancing layer.

[0146] The main part of the trench is arranged only in the balancing layer 4. At least 50% of the total volume TV of the trench can be arranged only in the balancing layer. Figure 3c In the non-limiting example shown in Figure 3c is Figure 3b Alternatively or additionally, a major part of the total number of grooves may be provided only in the balancing layer. Figure 3c In the embodiment, 24 grooves are provided only in the balancing layer, and 9 grooves are also provided in the upper layer arrangement structure 2, see Figure 3b .

[0147] Embodiments of the superposition structure 2 of the second aspect may be the same as those of the first aspect, reference being hereby made to those parts of the disclosure.

[0148] In some embodiments, the upper arrangement 2 can be laminated to the balancing layer 4. In turn, at least some of the upper layers can be laminated to each other. For example, the upper layer and the balancing layer can be provided as sheets, or can be provided on a roller mill and can be laminated to each other under heat and pressure. These sheets can be stacked on each other and can be laminated to each other, for example, in a hot press or a multi-day static press. The layers provided on the roller mill can be laminated to each other in a continuous process. In some embodiments, the balancing layer can be co-extruded with at least one upper layer, for example, with all upper layers except the wear layer and / or the printing layer.

[0149] like Figure 3a-3c , Figure 4a-4c and Figure 7d As shown in the embodiment of FIG. 1 , the groove 11 may be provided in the rear side 4a of the balancing layer, and thus preferably in the rear side 5 of the panel. For example, as described in the first aspect, the groove may be post-formed or pre-formed. Figure 5bAs shown, it is conceivable that an internal groove may be provided in the balancing layer 4. The internal groove may be preformed, for example, during the manufacturing process of the balancing layer and / or the panel, for example by (co)extrusion. As described above, the internal groove 10 may have walls along one horizontal direction and a vertical direction of the panel, and may be open towards another horizontal direction.

[0150] All the grooves 11 may be arranged in the balancing layer 4 only as shown in the figure, for example Figure 3a , Figure 4b-4c , Figure 5b and Figure 7d The embodiments in .

[0151] Generally in this context, for the first, second and third aspects, the grooves 11 may be provided on the inner side of all edge portions 1a-1d of the panel along the first horizontal direction X and the second horizontal direction Y, see e.g. Figure 1c-1d and Figure 3c Furthermore, one edge portion 16 or preferably both edge portions of the groove may be bent along the longitudinal extension of the groove. The groove may be open towards the rear side.

[0152] The balancing layer 4 may have a thickness T4 that varies along the first horizontal direction X and / or the second horizontal direction Y of the panel, for example by having grooves 11 at least partially arranged in the balancing layer. Figure 3a-3c , Figure 4a-4b and Figure 7d The embodiment in shows a varying thickness along the second horizontal direction Y. Optionally, the thickness may also vary along the first horizontal direction X, for example by providing grooves in the edge portion of the panel along the first horizontal direction X, see for example Figure 3c .

[0153] like Figure 4c and Figure 5b As shown, the balancing layer 4 may have a substantially constant thickness. For example, the balancing layer may be (co)extruded with at least one upper layer of the superlayer arrangement 2.

[0154] In some embodiments, Figure 4a-4b As shown, the thickness T4 of the balancing layer is greater than the thickness TU of the upper layer of the superstructure 2. Preferably, the upper layer is the uppermost layer 2a of the superstructure, such as a wear-resistant layer, but other upper layers are also conceivable. Figure 4b As shown, the thickness T4 of the balancing layer may be greater than the thickness TU of each upper layer in the upper layer arrangement.

[0155] Typically for the second aspect, the thickness T4 of the balancing layer 4 may be at least 20%, such as at least 35% or at least 50% of the panel thickness T1 .

[0156] The groove depth GD of the groove 11 may be greater than 20%, for example greater than 30% or even greater than 40% of the thickness T4 of the balancing layer 4. In some embodiments, the groove depth GD may be greater than 20% of the panel thickness T1, for example greater than 30% or greater than 40% of the thickness T1.

[0157] For example Figure 3a-3b , Figure 4a-4c , Figure 5b and Figure 7d The embodiment in Figure 1 shows that the innermost part 11a of any, some or even all grooves can be spaced apart from the upper arrangement structure 2 by a distance Sb in the vertical direction Z of the panel. The distance Sb can be greater than 0.25 times the thickness TU of the uppermost layer 2a (e.g. the wear layer). However, preferably, the distance is greater than 0.50 times or even greater than 1.0 times the thickness TU of the uppermost layer 2a.

[0158] In some embodiments of the first and second aspects, the groove depths GD of the grooves 11 are substantially the same, see e.g. Figure 1e , Figure 2b-2d , Figure 3a , Figure 4a-4c , Figure 5a -c, Figure 6b-6c and Figure 7d For example, Figure 2a and Figure 3b As shown, it is also conceivable that the groove depths GD of at least two grooves are different. Figure 2a , Figure 3b and Figure 7a The embodiment in shows the groove depth GD of one or several grooves 11, which are preferably edge grooves arranged at edge portions, such as long edge portions 1a, 1b, which may be smaller than the groove depth GD of other grooves, such as grooves arranged horizontally inward of the edge grooves along the second horizontal direction Y.

[0159] For example Figure 3b However, it can be applied to any embodiment of the second aspect, for example, Figure 3a , Figure 3c , Figure 4a-4c , Figure 5b and Figure 7d-7f In the embodiment of FIG. 1 , the average trench depth GA of the trench 11 may be less than the thickness T4 . Figure 3b A mean depth trench 11 ' is schematically shown.

[0160] Alternatively, if Figure 2b and Figure 4bAs shown, the panel may include at least one reinforcing element 13, such as a glass fiber layer. The at least one reinforcing element 13 may be arranged in a central portion of the panel, preferably at a distance d1 from the front side 12, the distance d1 being 35% to 65% of the distance d2 between the innermost portion 11a of the panel and the front side 12.

[0161] The upper arrangement structure 2 in any embodiment of the first aspect and the second aspect, for example Figure 1c-1e , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c , Figure 5a-5c , Figure 6a-6c , Figures 7a-7f , Figures 8a-8d and Figure 9a-9b Any embodiment of the present invention may include a thermoplastic polymer such as PVC and optionally a filler such as CaCO 3 In fact, in some embodiments, each of the upper layers 2a, 2b, 2c, 2d may comprise a thermoplastic polymer such as PVC and optionally a filler. The upper arrangement may comprise a wear layer and / or a printed layer, such as a printed film. Both layers may comprise a thermoplastic polymer such as PVC. In the same manner, Figure 1c-1e , Figure 2a-2d , Figure 5a , Figure 5d , Figure 6a-6c , Figure 7a-7c , Figure 8a-8b , Figure 8d and Figure 9a In any embodiment of the present invention, the lower layer arrangement 3, for example each of the at least one lower layer 3a, 3b, may comprise a thermoplastic polymer such as PVC and optionally a filler such as CaCO 3 Optionally, the amount of thermoplastic polymer in the balancing layer 4 may be higher than the amount of thermoplastic polymer in the upper arrangement 2 and / or the lower arrangement 3 .

[0162] Furthermore, any embodiment of the first aspect and the second aspect—e.g. Figure 1c-1e , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c , Figure 5a-5c , Figure 6a-6c , Figures 7a-7f , Figures 8a-8d and Figure 9a-9b In any of the embodiments of the present invention, the balancing layer 4 may include a thermoplastic polymer such as PVC and optionally a filler such as CaCO 3 .

[0163] Figure 1c-1e , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c , Figure 5a-5c , Figure 6a-6c , Figures 7a-7f , Figures 8a-8d and Figure 9a-9b The panel 1 in any of the embodiments may be a panel itself, for example, constructed to be loosely laid or glued to an underlying construction, or it may be a middle portion of a panel comprising a mechanical locking system 20 arranged in the edge portions 1a, 1b, 1c, 1d. In the latter case, the mechanical locking system may not be visible in the drawings, but may be understood to be implicit. On the other hand, Figure 6a-6c , Figure 7a-7c , Figure 8a-8b , Figure 8d and Figure 9a An embodiment of a floor panel 1, 1' according to the first aspect is shown, and Figure 7d-7f , Figure 8c and Figure 9b 1 , 1 ' according to the second aspect. The panels 1, 1 ' in these figures will be described by a general upper arrangement 2 and / or lower arrangement 3. However, a person skilled in the art will appreciate that within the scope of the present disclosure, they may be embodied as any of the embodiments herein, for example as Figure 1c-1e , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c and Figure 5a-5d In particular, the material composition of any of these panels can be implemented in the same way.

[0164] Figure 6a-6c An embodiment of a panel 1 is shown in a bottom view and in a cross-sectional side view of the panel along long edge portions 1a, 1b and short edge portions 1c, 1d. The embodiments described herein for the panel 1 are equally possible for the adjacent panel 1'.

[0165] Any panel disclosed herein—e.g. Figure 1c-1e , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c , Figure 5a-5d , Figure 6a-6c , Figures 7a-7f , Figures 8a-8d and Figure 9a-9b Any panel in the balancing layer 4 of the panel 1 may comprise a mechanical locking system 20 according to the third aspect for locking the panel 1 horizontally and / or vertically to an adjacent panel 1'. Such a mechanical locking system comprises a mating surface 21 which is arranged in an edge portion 1a, 1b, 1c, 1d of the panel 1 and is configured to mate with a mating surface 21 of an adjacent panel 1'. The mating surface 21 is at least partially located in the balancing layer 4 of the panel 1.

[0166] The panel 1 may be configured to be locked to an adjacent similar panel 1' at edge portions, such as the long edge portions 1a, 1b and the short edge portions 1c, 1d, by an angle A relative to each other and / or by a vertical displacement V. Figure 6b , Figure 7a-7b and Figure 7d-7e as well as Figure 6c , Figure 7c , Figure 7f , Figures 8a-8d and Figure 9a-9b An embodiment of a panel 1 is shown which is configured to be locked by angling A and by vertical displacement V, respectively. Figures 8a-8d The panels 1 , 1 ' in 9a-9b are shown around their short edge portions 1c, 1d, but alternatively or additionally it is equally conceivable to use any such mechanical locking system on the long edge portions 1a, 1b of the panels.

[0167] Typically, the mechanical locking system 20 of each panel 1, 1 ' may include at least one mating surface 21, preferably at least one locking surface 22, 23 and / or at least one guiding surface 24, 25. The at least one mating surface 21 may be arranged in an edge portion or an opposing edge portion, such as a short edge portion 1c, 1d and / or a long edge portion 1a, 1b. A person skilled in the art will appreciate that within the scope of the present disclosure, the mating surface 21 may be a first mating surface arranged in a first edge portion, such as a long edge portion 1a, 1b or a short edge portion 1c, 1d, and the mechanical locking system may also include a second mating surface 21 arranged in a (opposite) second (opposite) edge portion, such as a short edge portion 1c, 1d or a long edge portion 1a, 1b. The second mating surface 21 may be at least partially located in the balancing layer 4.

[0168] In some embodiments, the panels 1, 1' can be formed by providing the upper layers 2a, 2b, 2c, 2d and the balancing layer 4 as sheets or on a rolling mill and then laminating them to each other under heat and pressure. Where applicable, for example in the first aspect, the lower layers 3a, 3b can also optionally be provided as sheets or from a rolling mill and can be laminated to each other and to the other layers of the panel under heat and pressure. As an alternative to the above, the balancing layer can be co-extruded with at least one upper layer and / or lower layer. In any of these cases, before the mechanical locking system is formed in the panel 1, 1', the balancing layer 4 can extend into the edge portions 1a-1d of the panel, see for example Figure 1c-1e , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c and Figure 5a-5d The mechanical locking system may be formed by removing material from the edge portions 1a-1d. Figure 6a-6c , Figures 7a-7f , Figures 8a-8d and Figure 9a-9b In the embodiment of the present invention, after forming the mechanical locking system, a part of the balancing layer can be maintained in the edge portion. In particular, the balancing layer can be maintained in substantially the same vertical position.

[0169] For example Figure 6b-6c , Figure 7a , Figure 7d , Figures 8a-8d and Figure 9b The embodiment in FIG. 1 shows panels 1, 1', wherein the mating surface 21 is a locking surface 22, 23, which is configured to engage with a locking surface 23, 22 of an adjacent panel 1' / panel 1 in a locked state. As shown, the locking surface 22, 23 may be at least partially located in the balancing layer 4 of the respective panel 1, 1'. Typically, the locking surface 22, 23 may be a vertical and / or horizontal locking surface 22, 23. In FIG. Figure 7a In the embodiment, the locking surface 22 comprises an upwardly facing horizontal recessed portion of the mating surface 21. Figure 7a In the embodiment, the lowest horizontal recessed portion facing upward is the surface of the balancing layer 4.

[0170] For example Figure 7b-7c , Figure 7e-7f and Figure 9a-9b The embodiment in the figure shows a panel 1, 1 ', wherein the mating surface 21 is a guide surface 24, 25, which is configured to guide the adjacent panel 1 ' / panel 1 during locking. The guidance can be achieved by the guide surface 24, 25 cooperating or engaging with the mating surface 21 (e.g., guide surface 25, 24) of the adjacent panel during locking. As shown, the guide surface 24, 25 can be at least partially located in the balancing layer 4 of the corresponding panel 1, 1 '. Typically, the guide surface 24, 25 can guide the adjacent panel vertically and / or horizontally.

[0171] For example Figure 6b-6c As shown, the mechanical locking system 20 of the panel 1 - for example, the mechanical locking system on the long edge portions 1a, 1b and / or the short edge portions 1c, 1d - may include locking elements 8, 8' arranged on the strips 6, 6', which are configured to engage with the locking grooves 14, 14' of the adjacent panels 1' for horizontal locking. The strips 6, 6' may extend horizontally inward and may include portions that are thinner than the locking elements 8, 8'. The balancing layer 4 may extend at least partially through the locking elements 8, 8' and / or the locking grooves 14, 14'. In addition, the mating surface 21 may be located on the locking elements 8, 8' and / or in the locking grooves 14, 14'. In some embodiments, and for example as Figure 6b-6c , Figure 7c-7f , Figures 8a-8d and Figure 9a-9b As shown in , the uppermost surface 8a, 8a' of the locking element may comprise a part of the balancing layer and the mating surface 21, eg the locking surface 22 and / or the guiding surface 24 may be provided in the uppermost surface 8a, 8a'.

[0172] The balancing layer 4 may extend at least partially along the strips 6, 6', for example along the upper part of the strips. For example, the balancing layer 4 may extend along a portion of the strips 6, 6' or the entire upwardly facing surface. Figure 7a-7b , Figure 7d-7f , Figure 8a , Figure 8c-8d and Figure 9a-9b As shown in , the uppermost surface 6a, 6a' of the strip may comprise a part of the balancing layer. A mating surface 21, such as a locking surface 22 and / or a guiding surface 24 may be provided in the uppermost surface 6a, 6a'.

[0173] For example Figure 7f and Figure 8a As shown in the figure, the transition surface 26 from the uppermost surface 6a' of the strip 6' to the locking element 8', for example the inner wall 8b' of the locking element, may comprise a portion of the balancing layer 4. The uppermost surface 6a' may be arranged horizontally inside the locking element 8'. This embodiment may be particularly advantageous on the short edge portion 1d, where particularly high stresses may occur.

[0174] Furthermore, the mechanical locking system 20 of the panel 1, e.g. on the long edge portions 1a, 1b and / or the short edge portions 1c, 1d, may comprise a tongue portion 9, 9' configured to engage with a tongue groove 7, 7' of an adjacent panel 1' for vertical locking. The balancing layer 4 may extend at least partially through the tongue portion 9, e.g. through a lower part of the tongue portion. For example, Figure 6b-6c , Figures 7a-7f , Figures 8a-8d and Figure 9a-9b As shown in , the mating surface 21, such as the locking surfaces 22, 23 and / or the guiding surfaces 24, 25, may be located on the tongue part 9, 9'. The lowermost surface 9a, 9a' of the tongue part may comprise a part of the balancing layer, and the mating surface 21 may be provided in the lowermost surface 9a, 9a', see e.g. Figure 7a-7b , Figure 7d-7f , Figure 8a , Figure 8c-8d and Figure 9a-9b .

[0175] For example Figure 6bAs shown, the tongue portion 9 preferably provided in the long edge portion 1a may comprise a tongue 18 formed integrally with the panel. Figure 6c As shown, the tongue portion 9', preferably arranged in the short edge portion 1d, may comprise a separate and preferably flexible tongue 18', which is configured to be arranged in a displacement groove 19 arranged at an edge portion of the panel, for example the short edge portion 1d. Figure 6c A non-limiting embodiment of a tongue 18 ′ is shown in a sectional top view in . This so-called bristle tongue is preferably formed in one piece and comprises a flexible protrusion 28 .

[0176] The mating surface 21 of the adjacent panel 1', for example a locking surface and / or a guiding surface, may be a general mating surface provided at the edge portion. However, alternatively, it may be located at least partially in the balancing layer 4 of the adjacent panel 1'. In a first example, for example Figures 8a-8d shown (but generally applicable to e.g. Figure 6b-6c and Figures 7a-7f In the embodiment of FIG. 4 , in the locked state, a portion of the vertical and / or horizontal locking surface 22 of the panel 1 including the balancing layer 4 may be configured to engage with a portion of the vertical and / or horizontal locking surface 23 of the panel 1 ′ including the balancing layer 4. In a general second example, for example Figure 7b-7c , Figure 7e-7f and Figure 9a-9b As shown in , during locking, a portion of the vertical and / or horizontal guide surface 24 of the panel 1 including the balancing layer 4 may be configured to cooperate with a portion of the vertical and / or horizontal guide surface 25 of the panel 1 ' including the balancing layer 4. The third general example includes all partial configurations of the first and second examples.

[0177] It should be emphasized that the roles of the panel 1 and the adjacent panel 1 ′ described herein may be interchanged.

[0178] In a first example, and for example Figure 7b-7c , Figure 7e-7f and Figure 9a-9b As shown in the figure, the guide surface 25 of the panel 1' may be arranged in the edge parts 1a, 1c, may be located at least partially in the balancing layer 4 of the panel 1', and may be configured to cooperate with the mating surface 21 of the panel 1 during locking. Embodiments and examples of the guide surface 25 of the panel 1' have been described above with respect to these figures. Figure 7b , Figure 7e and Figure 9a-9b As shown in , such a mating surface 21 can be provided on the uppermost surface 6a of the strip 6 and / or on the locking element 8. Figure 9a-9bAs shown in , such a mating surface 21 can also be provided in a wall 27 in the upper edge of the panel 1, optionally along a vertical plane VP defined by the juxtaposed upper edges of the panels 1, 1'. Figure 7c and Figure 7f As shown in FIG. 4 , such a mating surface 21 may be provided in a wall 27 arranged along said vertical plane VP in the upper edge of the panel 1 and / or on a separate, preferably flexible tongue 18 ′.

[0179] In the second example, for example Figures 8a-8d As shown in , the locking surface 23 of the panel 1 ' may be arranged in the edge portion 1c, may be located at least partially in the balancing layer 4 of the panel 1 ', and may be configured to engage with the locking surface 22 of the panel 1 in the locked state of the panels 1, 1 '. Figures 8a-8d As shown in FIG. 5 , such a locking surface 22 may be provided on the uppermost surface 6a of the strip 6 and / or on the locking element 8, for example on the uppermost surface 8a, the inner wall 8b and / or the outer wall 8c thereof.

[0180] A person skilled in the art will understand that within the scope of the present disclosure, in some embodiments, the mechanical locking system 20 includes a mating surface 21 that is at least partially located in the balancing layer 4, and further, includes a mating surface 21 that is only arranged in the upper structure 2 and / or the lower structure 3.

[0181] It is emphasized again that the groove arrangement 10 is optional with respect to the third aspect. Figures 8a-8d and Figure 9a-9b The embodiment in is shown without any grooves 11 therein, although for example Figure 6a-6c , Figure 7a and Figure 7d The grooves shown in any of the embodiments are obviously not excluded. It should also be noted that in any of the embodiments herein, the grooves may be provided between the mechanical locking system 20 provided at a pair of opposite edge portions (e.g. short edge portions 1c, 1d). For example Figure 6c As shown in , the groove length GL may be smaller than the distance DM between the mechanical locking systems 20 located at a pair of opposite edge portions, for example, smaller than the distance DM between the inner portions of the mechanical locking systems 20 .

[0182] In some embodiments, and as Figure 9a as well as Figure 8a-8cAs shown in , the groove arrangement 10 may include a calibration groove 15 for facilitating the locking of the panels, for example when the panels have different / diverging thicknesses or when no underlying element (e.g. foam) is used. The calibration groove 15 may be arranged in the edge portion of the adjacent panels 1', preferably in the rear side 5 of the adjacent panels 1'. Furthermore, the calibration groove 15 may be arranged adjacent to the locking groove 14, for example, immediately adjacent to the locking groove 14.

[0183] Table 1 - Examples of layer combinations in the first aspect

[0184] A1 A2 A3 A4 A5 upper layer L1 U1 L1 U1 L1 Balance layer L3 L3 L3 U2 U2 Lower level L1 U1 E1 U1 E1

[0185] Table 2 - Examples of layer combinations in the first aspect

[0186] B1 B2 B3 B4 B5 First upper level L2 U2 L2 L2 U2 Second upper floor L1 U1 U1 L1 U1 Balance layer L3 U2 L3 L3 U2 Lower level L1 U1 U1 E1 E1

[0187] Table 3 - Examples of layer combinations in the second aspect

[0188] C1 C2 C3 C4 upper layer L1 U1 L1 U1 Balance layer L3 L3 U2 U2

[0189] Table 4 - Examples of layer combinations in the second aspect

[0190] D1 D2 D3 D4 D5 D6 First upper level L2 L1 L1 L1 U1 U2 Second upper floor L1 E1 U1 E1 E1 U1 Balance layer L3 L3 L3 U2 U2 U2

[0191] Table 5 - Examples of material compositions for the first and second aspects

[0192]

[0193] Tables 1 and 2 show non-limiting examples of layer combinations A1, ..., A5 and B1, ..., B5, respectively, of the first aspect, which can be envisaged for example Figure 1c-1e , Figure 2a-2d , Figure 5a , Figure 5c , Figure 6a-6c , Figure 7a-7c , Figure 8a-8b , Figure 8d and Figure 9a Furthermore, Tables 3 and 4 show non-limiting examples of layer combinations C1, ..., C4 and D1, ..., D6 of the second aspect, respectively, which can be envisaged for example Figure 3a-3c , Figure 4a-4c , Figure 5b , Figure 7d-7f , Figure 8c and Figure 9bAny panel in the above. A person skilled in the art will appreciate that within the scope of the present disclosure, a panel comprising any layer combination in Tables 1-4 may also include a wear resistant layer and / or a printed layer. In addition, a coating, such as a UV coating, may be provided on the upper layer arrangement. For layer combinations B1, ..., B5 and D1, ..., D6, the first upper layer may be disposed on the second upper layer. In general, each of the upper layer, the lower layer and the balancing layer may comprise a thermoplastic polymer such as PVC. Preferably, each of the layers comprises a filler, such as CaCO 3 Furthermore, each layer may comprise plasticizers and / or additives, such as stabilizers, impact modifiers, pigments or lubricants, and optionally foaming agents.

[0194] Non-limiting examples of material compositions L1-L3, U1, U2 and E1 for the upper, lower and balancing layers, expressed in weight percent (wt%), are shown in Table 5. These material compositions can be applied to any layer combination in Tables 1-4.

[0195] In some embodiments, the upper layer and the balancing layer may include different material compositions, see A1-A5, B1, B3-B4, C1-C4, and D1-D5. In addition, in some embodiments, the upper layer and the balancing layer may include substantially similar material compositions, see B2, B5, and D6. In some embodiments of the first aspect, the upper layer and the lower layer may include different material compositions, see A3, A5, and B4-B5. However, in some embodiments, the upper layer and the lower layer may include substantially similar material compositions, see A1, A2, A4, and B1-B3. In any of these embodiments, the thickness of the layers having substantially similar material compositions may be different.

[0196] Aspects of the present disclosure have been described above primarily with reference to several embodiments. However, as will be readily appreciated by those skilled in the art, other embodiments than those disclosed above, as defined by the appended patent claims and the items in the following examples section, are also possible within the scope of the present disclosure. For example, in any embodiment herein, Figure 2d As schematically shown in FIG. 5 , a separately formed bottom layer element 17 , such as foam or cork, may at least partially cover the rear side 5 of the panel, which may be arranged in the underlying arrangement 3 (first aspect) or in the balancing layer 4 (second aspect).

[0197] Example

[0198] The following examples further describe and demonstrate embodiments within the scope of the present invention. These examples are given for illustrative purposes only and should not be construed as limitations of the present disclosure, as many variations thereof are possible without departing from the spirit and scope of the present disclosure.

[0199] In order to test the curling effect of the panel according to the first aspect, the following measurements were made using the indicated method on each of a set of samples S1, S2 and S3, each sample having horizontal dimensions of 160×160 mm. Figure 10a-10c Shown in a photograph with a ruler indicating millimeters. Fig.10a A photograph of sample S1 (reference) in which a groove completely penetrates the balancing layer as the bottom layer is produced is shown, while Figure 10b-10c Photographs of samples S2, S3 produced according to the first aspect with the grooves provided only in the lower layer are shown.

[0200] Compositions COM1, COM2 and WL0 were used in the samples. In terms of weight percentage, COM1 contained 16.92% PVC (Norvinyl TM S5745), 76.14% CaCO 3 (Greenafiller TM 0-100), 0.34% stabilizer (Baerostab TM CT 1228R), 0.08% lubricant (Baerolub TM PA Special), 6.43% plasticizer (Eastman TM 168) and 0.08% black pigment. In addition, COM2 contains 37.04% PVC (Norvinyl TM S5745), 50.00% CaCO 3 (Greena-filler TM 0-100), 0.74% stabilizer (Baerostab TM CT 1228R), 0.19% lubricant (Baerolub TM PA Special), 11.85% plasticizer (Eastman TM 168) and 0.19% red pigment. WL0 contains additives and plasticizers and 75 wt% PVC. The thickness of the layers of the samples, the total thickness of the samples and the groove depth GD are specified in millimeters in Table 6, and the material composition of the layered construction is specified in Table 7. Each of the samples S1, S2 and S3 contains a wear layer and a print layer, the wear layer contains additives and plasticizers and 75 wt% PVC, and the print layer contains PVC and white pigment and has a thickness of 0.04 mm.

[0201] Table 6 – Sample data

[0202]

[0203] By using Fig.9c , measurements are performed on each of the samples S1, S2 and S3 using an indicator device 30 schematically shown in a side view of FIG. The indicator device comprises a pair of abutment portions 31 fixedly arranged on opposite (two) sides 33 of a rod 32 located on the same horizontal plane. A movable indicator 34 arranged between the abutment portions 31 is configured to measure a deviation Δz of the movable indicator 34 relative to the abutment portions 31 along a direction F parallel to the movement direction of the movable indicator 34.

[0204] Figure 9d Shown along Fig.9c Cross-sectional top view of section EE in FIG. Fig.9e Shown with Fig.9c Same cross-sectional top view, but with the indicator device 30 rotated 90 degrees in the XY plane.For each sample, measurements were taken along the sample's center lines CX and CY, which are parallel to the first horizontal direction X and the second horizontal direction Y, respectively.

[0205] Table 7 – Material composition and test results of samples

[0206]

[0207] More specifically, the abutment portion 31 abuts the sample along the center line CX at a distance of 5 mm from the edge of the sample, and the movable indicator 34 engages with the center point C0 of the sample, see Figure 9d From this, the vertical deviation Δz is derived at a temperature of 22°C 1 (X). Similarly, a similar process is used to derive the vertical deviation Δz along the center line CY at the same temperature. 1 (Y), see Fig.9e .

[0208] The sample was then heated to a temperature of 80°C and maintained at that temperature for 6 hours. Thereafter, the sample was acclimated to a temperature of 22°C for 24 hours. After the sample acclimated, the vertical deviations Δz(X) and Δz(Y) were remeasured using the same method as above to obtain Δz 2 (X) and Δz 2 Table 7 summarizes the values ​​of Δz 12 (X) = Δz 1 (X)-Δz 2 (X) and Δz 12 (Y) = Δz 1 (Y)-Δz 2 It can be seen that the curling effect of S2 and S3 is significantly reduced along the first horizontal direction X and the second horizontal direction Y compared to sample S1 as a result of shifting the balancing layer according to the first aspect.

[0209] The curling effect was also tested on sample S5 according to the first aspect and samples S7 and S8 according to the second aspect. Fig.11a shows a photograph of a sample S5 produced according to the first aspect, and Figure 11c-11d The photographs of samples S7 and S8 produced according to the second aspect are shown. The grooves in S5 (S7-S8) are only provided in the lower layer (only in the balancing layer). In order to observe the improvement, the sample S5 (S7 or S8) is compared with the reference sample S4 (S6), which is produced with grooves that completely penetrate the balancing layer as the bottom layer. The photographs of S4 and S6 are respectively Fig.10d and Fig.11b Shown in.

[0210] The curling effect was tested using standard ISO 23999:2018, modified so that each sample S4-S8 had dimensions of 160×160 mm (instead of 229×229 mm). Compositions COM1 (as described above), COM3 and COM4 were used in the samples. In terms of weight percentage, COM3 contained 56.34% PVC (Norvinyl TM S5745), 28.17% CaCO 3 (Greenafiller TM 0-100), 1.13% stabilizer (Baerostab TM CT 1228R), 0.28% lubricant (Baerolub TM PA Special) and 14.08% plasticizer (Eastman TM 168), and COM4 contains 37.11% PVC (Nor-vinyl TM S5745), 50.09% CaCO 3 (Greenafiller TM 0-100), 0.74% stabilizer (Baerostab TM CT 1228R), 0.19% lubricant (Baerolub TM PA Special) and 11.87% plasticizer (Eastman TM 168).

[0211] The thickness and groove depth GD of S4-S8 in millimeters are summarized in Table 6, and the material composition is specified in Table 8. Each sample S4-S8 includes a PVC wear layer and a printed film including PVC, having a thickness of approximately 0.60 mm and 0.06 mm, respectively. The difference Δz measured using the indicator method 12 (X) and the difference Δz 12The average values ​​of (Y) and curl measured using ISO 23999:2018 are summarized in mm in Table 8. It can be seen that the curling effect is reduced using both tests S5 (first aspect) compared to sample S4. In particular, Δz 12 (Y) significantly decreased. In addition, the curling effect of S7 and S8 (second aspect) was significantly reduced using both tests compared to sample S6.

[0212] Table 8 – Material composition and test results of samples

[0213]

[0214]

[0215] Table 9 – Material composition and sample data

[0216]

[0217] A pair of samples Q2 and Q4 according to the first aspect were tested for residual concavity by standard ASTM F1914-18 (ASTM F1700 product specification). The elastic sample Q2 and the rigid sample Q4 were compared with reference samples Q1 and Q3, respectively, which had similar layer combinations but did not include the lower layer LL present in Q2 and Q4. Each sample Q1-Q4 had two upper layers UL1, UL2, a balancing layer BL and horizontal dimensions of 50×50 mm. The grooves in Q2 and Q4 were only provided in the lower layer, while the grooves in Q1 and Q3 completely penetrated the balancing layer BL provided as the bottom layer. An IXPE foam with a thickness of 1.5 mm was used as the bottom layer, thereby covering the grooves. Figures 12a-12d Photographs of samples Q1-Q4 during testing are shown respectively.

[0218] Compositions COM4 (described above), COM5 and COM6 were used in the samples. COM5 contained 37.59% PVC (Norvinyl TM S6261)), 56.38% CaCO 3 (Greenafiller TM 0-100), 0.21% pigment (Printex TM Carbon Black), 3.76% stabilizer (Baerostab TM CT 1229P), 0.28% processing aids and lubricants (Baerocid TM SMS1A), 0.28% lubricant (Baerolub TM PA 200), 1.13% impact modifier (AddstrengthTM CPE-3516) and 0.38% impact modifier (Kane Ace TM B580) and COM6 contain 27.32% PVC (Norvinyl TM S6261), 68.30% CaCO 3 (Greena-filler TM 0-100), 0.15% pigment (Printex TM Carbon Black), 2.73% stabilizer (Baerostab TM CT 1229P), 0.20% processing aids and lubricants (Baerocid TM SMS1A), 0.20% lubricant (Baerolub TM PA 200), 0.82% impact modifier (Addstrength TM CPE-3516) and 0.27% impact modifier (Kane Ace TM B580).

[0219] The material combinations, layer thicknesses (in millimeters) and groove depths GD (in millimeters) of Q1-Q4 are specified in Table 9. Samples Q1 and Q3 were both destroyed in the test, while samples Q2 and Q4 resulted in residual dishing of 2.896% and 1.390%, respectively. Therefore, it can be concluded that the sample properties related to residual dishing are significantly improved when the balancing layer is sandwiched between the upper and lower layer arrangements.

[0220] Note that similar results can be derived for the second aspect. Indeed, by analogy, one skilled in the art would expect that a more complete bottom layer (underlayer or balancing layer) including trenches would perform better in terms of residual dishing.

[0221] Illustrative Embodiments

[0222] Other aspects of the present disclosure are provided below. Embodiments, examples, etc. of these aspects are largely similar to the embodiments, examples, etc. described above. Reference is therefore made to the detailed description above.

[0223] Item 1. A thermoplastic-based building panel (1), such as a floor panel, comprising:

[0224] An upper layer arrangement (2) comprising at least one upper layer (2a, 2b, 2c),

[0225] A lower layer arrangement (3) comprising at least one lower layer (3a, 3b), and

[0226] a balancing layer (4) arranged between the lower arrangement structure and the upper arrangement structure,

[0227] The building panel further comprises a groove arrangement (10), the groove arrangement comprising at least one groove (11), preferably a plurality of grooves.

[0228] Item 2. The building panel according to item 1, wherein the groove arrangement is provided in the underlying arrangement (3).

[0229] Item 3. The building panel according to item 1 or 2, wherein the at least one groove (11) is provided in the rear side (5) of the underlying arrangement (3), preferably in the bottom layer (5') thereof.

[0230] Item 4. A building panel according to any of the preceding items, wherein the groove depth (GD), preferably the maximum groove depth, of at least one of the grooves is greater than 20% of the thickness (T3) of the underlying arrangement structure (3) and / or the thickness (T1) of the building panel, for example greater than 30% of the thickness or greater than 40% of the thickness.

[0231] Item 5. The building panels of any one of the preceding items, wherein a major portion of the groove is disposed completely below the balancing layer.

[0232] Item 6. The building panel according to any of the preceding items, comprising a plurality of grooves in the underlying arrangement, wherein an innermost portion (11a) of at least one groove is spaced a distance (Sa) from the balancing layer (4) in a vertical direction of the building panel.

[0233] Item 7. A building panel according to any of the preceding items, wherein the combined thickness (TL), e.g. the maximum combined thickness, of the underlying arrangement structure (3) and the balancing layer (4) is at least 20%, e.g. at least 35% or at least 50%, of the thickness (T1) of the building panel.

[0234] Item 8. The building panel according to any of the preceding items, wherein a thickness (T4), e.g. a maximum thickness, of the balancing layer (4) is at least 5%, e.g. at least 10% or at least 20% of the thickness (T1 ) of the building panel.

[0235] Item 9. A building panel according to any of the preceding items, wherein the thickness (T4), e.g. the maximum thickness, of the balancing layer (4) is greater than the thickness (TU) of an upper layer of the superstructure, preferably the uppermost layer (2a) of the superstructure.

[0236] Item 10. A thermoplastic-based building panel (1), such as a floor panel, comprising:

[0237] An upper layer arrangement (2) comprising at least one upper layer (2a, 2b, 2c), and

[0238] As a balancing layer (4) of the bottom layer (5') of a building panel,

[0239] The building panel further comprises a groove arrangement (10) comprising a plurality of grooves (11), a major part of the grooves being arranged only in the balancing layer.

[0240] Item 11. The building panel of item 10, wherein all of the grooves are provided in the balancing layer only.

[0241] Item 12. The building panels of item 10 or 11, wherein the grooves are provided in the back side (4a) of the balancing layer.

[0242] Item 13. The building panels of any preceding items 10-12, wherein the major portion comprises a major portion of the total groove volume (TV) and / or a major portion of the total number of grooves.

[0243] Item 14. The building panel according to any of the preceding items 10-13, wherein the thickness (T4), e.g. the maximum thickness, of the balancing layer is greater than the thickness (TU) of an upper layer of the superstructure, preferably the uppermost layer (2a) of the superstructure.

[0244] Item 15. The building panel according to any of the preceding items 10-14, wherein a thickness (T4), e.g. a maximum thickness, of the balancing layer (4) is at least 20%, e.g. at least 35% or at least 50%, of the thickness (T1) of the building panel.

[0245] Item 16. The building panel of any of the preceding items 10-15, comprising a plurality of grooves in the balancing layer, wherein an innermost portion (11a) of at least one groove is spaced a distance (Sb) from a superposition structure in a vertical direction of the building panel.

[0246] Item 17. The building panel according to any of items 10 to 16, wherein the groove depth (GD) of the groove is greater than 20% of the thickness (T4) of the balancing layer and / or the thickness (T1) of the building panel (e.g. floor panel), such as greater than 30% of the thickness or greater than 40% of the thickness.

[0247] Item 18. The building panel according to any of the preceding items 1-17, comprising a plurality of grooves, wherein the groove depth (GD), preferably the maximum groove depth, of at least two of the grooves is different.

[0248] Item 19. The building panel according to any of preceding items 1-18, wherein the balancing layer is a continuous layer.

[0249] Item 20. The building panel according to any of the preceding items 1-19, comprising at least one reinforcement element, such as a fiberglass layer.

[0250] Item 21. The building panel according to any of the preceding items 1-20, further comprising a mechanical locking system (20) in the edge portions (1a, 1b; 1c, 1d) for horizontally locking the building panel and / or vertically locking the building panel to an adjacent building panel.

[0251] Item 22. The building panel according to any of the preceding items 1-21, further comprising a mechanical locking system (20) according to item 23 or any of items 26-38.

[0252] Item 23. A thermoplastic-based building panel (1; 1'), such as a floor panel, comprising:

[0253] The upper arrangement structure (2) and / or the lower arrangement structure (3),

[0254] a balancing layer (4) comprising a thermoplastic polymer, and

[0255] A mechanical locking system for horizontally locking and / or vertically locking a building panel (1; 1') to an adjacent building panel (1'; 1), the mechanical locking system comprising a mating surface (21) provided in an edge portion (1a, 1b; 1c, 1d) of the building panel (1; 1') and configured to mate with a mating surface (21) of an adjacent building panel (1'; 1),

[0256] The mating surface (21) of the mechanical locking system (20) is at least partially located in the balancing layer.

[0257] Item 24. The building panel according to item 23, wherein a balancing layer is arranged between the lower arrangement structure (3) and the upper arrangement structure (2).

[0258] Item 25. The building panel according to item 23, wherein the balancing layer is a bottom layer (5') of the building panel.

[0259] Item 26. A building panel according to any of the preceding items 23 to 25, wherein the balancing layer extends at least partially through a locking element (8; 8') provided on the strip (6; 6') and / or through a locking groove (14; 14'), the locking element being configured to engage with a locking groove of the adjacent building panel (1') for horizontal locking.

[0260] Item 27. The building panels according to item 26, wherein the mating surface is located on the locking element (8; 8') and / or in the locking groove (14; 14').

[0261] Item 28. The building panels according to item 26 or 27, wherein the uppermost surface (8a; 8a') comprises a part of the balancing layer, the mating surface being preferably provided in the uppermost surface.

[0262] Item 29. The building panels according to any of the preceding items 23-28, wherein the balancing layer extends at least partially along the strip (6; 6'), for example along an upper part of the strip.

[0263] Item 30. The building panels according to item 29, wherein the uppermost surface (6a; 6a') comprises a portion of a balancing layer, the mating surface (21) being preferably arranged on the uppermost surface (6a; 6a').

[0264] Item 31. A building panel according to any of items 23-30, wherein the balancing layer extends at least partially through a tongue portion (9; 9'), for example through a lower part of the tongue portion, which is configured to engage with a tongue groove (7; 7') of an adjacent building panel for vertical locking.

[0265] Item 32. The building panels of item 31, wherein the mating surface is located on the tongue portion (9; 9').

[0266] Item 33. The building panels according to item 31 or 32, wherein the lowermost surface (9a; 9a') comprises a part of the balancing layer, the mating surface being preferably provided in the lowermost surface.

[0267] Item 34. A building panel according to any one of the preceding items 23-33, wherein the mating surface (21) is a first mating surface arranged in a first edge portion (1a, 1b; 1c, 1d) of the building panel, and the mechanical locking system also includes a second mating surface arranged in a second edge portion (1c, 1d; 1a, 1b) of the building panel, the first edge portion and the second edge portion are preferably arranged opposite to each other on the building panel, wherein the second mating surface is at least partially located in the balancing layer (4).

[0268] Item 35. A building panel according to any one of the preceding items 23-34, wherein the mating surface (21) is a locking surface (22; 23) configured to engage with a locking surface (23; 22) of an adjacent building panel in a locked state of the building panel and the adjacent building panel.

[0269] Item 36. A building panel according to any one of the preceding items 23-35, wherein the mating surface (21) is a guide surface (24; 25) which is configured to guide an adjacent building panel during the process of locking the building panel to the adjacent building panel, for example by mating or engaging with the mating surface (21) (e.g., the guide surface (25; 24)) of the adjacent building panel during the locking process.

[0270] Item 37. The building panel according to any of the preceding items 23-36, wherein the building panel further comprises a groove arrangement structure (10) comprising at least one groove (11), preferably a plurality of grooves.

[0271] Item 38. The building panels of any of the preceding items 23-37, wherein a building panel and an adjacent building panel are configured to be locked to each other by relative vertical displacement and / or angling of the building panels towards each other.

[0272] Item 39. The building panel according to any of the preceding items 1-38, wherein the upper layer arrangement (2), such as each of the at least one upper layer, comprises a thermoplastic polymer and optionally a filler.

[0273] Item 40. The building panel of any one of preceding items 1-39, wherein the superposition structure comprises a wear layer (2a) and / or a printed layer (2b), such as a printed film.

[0274] Item 41. The building panel according to any of the preceding items 1-40, wherein the balancing layer (4) comprises a thermoplastic polymer and optionally a filler.

[0275] Item 42. The building panel according to any of the preceding items 1-41, wherein the underlying arrangement (3), such as each of the at least one underlying layer, comprises a thermoplastic polymer and optionally a filler.

[0276] Item 43. The building panel according to any of the preceding items 1-42, wherein the amount of thermoplastic polymer in the balancing layer is higher than the amount of thermoplastic polymer in the superstructure and / or substructure.

[0277] Item 44. The building panels according to any of the preceding items 1-43, wherein at least one upper layer and / or lower layer of the building panels is extruded, such as coextruded.

[0278] Item 45. The building panel of any of the preceding items 1-22 or 37-44, wherein the groove arrangement (10) is post-formed after forming the panel (1) itself, preferably by removing material from the bottom layer (5') of the panel.

[0279] Item 46. The building panel of any one of preceding items 1-9 or 37-45, wherein an average groove depth (GA) of the plurality of grooves (11) is less than a thickness (T3) of the underlying arrangement.

[0280] Item 47. The building panel according to any one of preceding items 10-22 or 37-45, wherein an average groove depth (GA) of the plurality of grooves (11) is less than the thickness (T4) of the balancing layer.

[0281] Item 48. The building panel of any one of the preceding claims, comprising a groove arrangement (10) comprising at least one groove (11), wherein the at least one groove (11) comprises at least one opening at a downwardly facing surface of the building panel (1).

[0282] Item 49. The building panels of any one of the preceding claims, comprising a groove arrangement (10) comprising at least one groove (11), wherein the at least one groove (11) is defined by a panel portion located below the at least one groove (11).

[0283] Item 50. The building panels of item 35, wherein the locking surface (22) comprises an upwardly facing horizontal recessed portion of the mating surface (21).

[0284] Item 51. The building panel of item 50, wherein the upwardly facing horizontal recessed portion is the surface of the balancing layer (4).

[0285] Item 52. A panel assembly comprising a building panel (1) and an adjacent building panel (1'), wherein the building panel and / or the adjacent building panel is embodied as a building panel according to any of the preceding items 1-51.

Claims

1. A thermoplastic-based building panel (1) comprising: A superstructure (2) comprising a thermoplastic polymer, the superstructure (2) comprising at least one superstructure (2a, 2b, 2c), A balancing layer (4) comprising a thermoplastic polymer, the balancing layer serving as a bottom layer (5') of a building panel, and A groove arrangement structure (10), comprising a plurality of grooves (11), in, The groove depth (GD) of the groove (11) is greater than 20% of the thickness (T4) of the balancing layer (4) and / or 20% of the thickness (T1) of the building panel (1), and Wherein, a major portion of the groove (11) is only arranged in the balancing layer (4).

2. The building panel according to claim 1, wherein The major portion is at least 50% of the number of the grooves (11) and / or at least 50% of the total volume of the grooves (11).

3. The building panel according to claim 1, wherein All of the grooves (11) are arranged only in the balancing layer (4).

4. The building panel according to any one of claims 1 to 3, wherein The grooves are provided in the rear side (4a) of the balancing layer.

5. The building panel according to any one of claims 1 to 3, wherein The thickness (T4) of the balancing layer is greater than the thickness (TU) of the upper layer (2a, 2b, 2c) of the upper layer arrangement (2).

6. The building panel according to claim 5, wherein The upper layer is the uppermost layer (2a) of the upper layer arrangement structure.

7. The building panel according to claim 6, wherein The uppermost layer (2a) is a wear-resistant layer.

8. The building panel according to any one of claims 1 to 3, wherein The thickness of the balancing layer (4) is at least 4 times the thickness (TU) of the uppermost layer (2a) of the superstructure (2).

9. The building panel according to any one of claims 1 to 3, wherein The thickness (T4) of the balancing layer (4) is at least 20% of the thickness (T1 ) of the building panel.

10. The building panel according to any one of claims 1 to 3, wherein An innermost portion (11a) of at least one groove is spaced a distance (Sb) from the superposition structure (2) in a vertical direction (Z) of the building panel.

11. The building panel according to any one of claims 1 to 3, wherein The groove depth (GD) of the groove (11) is greater than 30% of the thickness (T4) of the balancing layer (4) and / or 30% of the thickness (T1) of the building panel.

12. The building panel according to any one of claims 1 to 3, wherein The groove arrangement (10) is post-formed after the building panel (1) itself is formed by removing material from the bottom layer (5') of the building panel.

13. The building panel according to any one of claims 1 to 3, wherein The superstructure (2) and / or the balancing layer (4) comprises a filler.

14. The building panels according to any one of claims 1 to 3, wherein A minor portion of the grooves (11) penetrates the superstructure (2) of the building panels, the minor portion and the major portion together corresponding to the total number of grooves and / or the total volume of the grooves.

15. The building panels according to any one of claims 1 to 3, wherein The average groove depth (GA) of the plurality of grooves (11) is less than the thickness (T4) of the balancing layer (4).

16. The building panels according to any one of claims 1 to 3, wherein The groove depths (GD) of at least two grooves (11) are different.

17. The building panels according to any one of claims 1 to 3, wherein Each groove (11) is an internal groove at least partially arranged in the balancing layer (4).

18. The building panels according to any one of claims 1 to 3, wherein The building panel (1) comprises at least one reinforcement element (13).

19. The building panels according to any one of claims 1 to 3, wherein An edge portion (1a, 1b, 1c, 1d) of a building panel (1) comprises a mechanical locking system (20) for horizontally and / or vertically locking the building panel to an adjacent building panel (1') or to a plurality of adjacent building panels (1').

20. The building panels according to any one of claims 1 to 3, wherein A separately formed base element (17) at least partially covers the rear side (5) of the building panel (1).

21. The building panels according to any one of claims 1 to 3, wherein The building panel (1) is a floor panel.

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