Method and apparatus for manufacturing plate element comprising cavity

Abstract

The present disclosure relates to a method for manufacturing a panel element (1) comprising a thermoplastic material, wherein the rear face (1e) of the panel element comprises a cavity region (2). The method comprises forming a first material (4) in a forming unit (11) forming the component (10), wherein the first material comprises a thermoplastic material; heating the first material; and hardening the shaped first material to form the protrusions (3) in the rear face (6a) of the substrate (6) wherein the substrate comprises a second material (5) comprising a thermoplastic material. A plate element comprising a cavity region created between the protrusions is thereby obtained.

Description

Technical Field

[0001] The present disclosure generally relates to a method and an apparatus for manufacturing a panel element comprising a thermoplastic material, wherein a back side of the panel element comprises a cavity region. The present disclosure also relates to the panel element, such as the panel itself. The panel can be a building panel, a floor panel, a wall panel, a ceiling panel, or a furniture component. Background Art

[0002] The weight of a panel, such as a floor panel, can be reduced in a variety of ways. WO 2013 / 032391 and WO 2014 / 007738 disclose panels comprising a thermoplastic material, which are provided with a specific groove structure on their back sides for reducing their weight. The groove structure can be formed by removing material from the back side, for example, using a rotating hopping tool or a skiving tool to remove the material. Improved methods for forming such grooves by machining tools are disclosed, for example, in WO 2020 / 180237 and WO 2022 / 050891.

[0003] There may be situations where it may be advantageous to form grooves or equivalently cavities without removing any material. For example, as disclosed in WO 2013 / 032391, they can be formed during the pressing of the panel, such as in a discontinuous press, by pressing as disclosed in WO 2021 / 018918 or by embossing as disclosed in WO 2021 / 180882 and PCT / SE2023 / 050596. However, so far, little is known about the details of such methods and similar methods. In addition, the final properties of panels including grooves formed by such methods and similar methods still need to be further developed / improved. Therefore, improved methods and apparatuses for providing such grooves or cavities are needed. However, at least in some applications, when the material is embossed to form a cavity, there is a risk of forming internal stresses in the panel element. For example, this may have a negative impact on the dimensional stability of the panel element. In addition, the method of forming a cavity by embossing may involve many operations in at least some applications, and these operations must be coordinated in a precise manner. Summary of the Invention

[0004] Therefore, an object of at least embodiments of the present disclosure is to provide a more efficient method for forming a cavity in a panel element.

[0005] Another object of at least embodiments of the present disclosure is to provide a panel element with reduced weight while improving the stability and / or the balance characteristics of the panel element.

[0006] Another object is to provide a corresponding apparatus for manufacturing a panel element.

[0007] Another object is to provide an improved plate element including a cavity region, which plate element is optionally manufactured according to an embodiment of the method described herein.

[0008] These and other objects and advantages, which will become apparent from the description, have been achieved by the various aspects, embodiments and examples described below.

[0009] According to a first aspect of the present disclosure, there is provided a method for manufacturing a plate element comprising a thermoplastic material, wherein the back surface of the plate element includes a cavity region. The method includes: forming a first material in a forming unit of a forming member, wherein the first material comprises a thermoplastic material; heating the first material; and hardening the formed first material to form protrusions on the back surface of a substrate, wherein the substrate preferably comprises a second material containing a thermoplastic material. Thereby, a plate element including a cavity region created between the protrusions is obtained.

[0010] By means of the first aspect, a cavity region can be created in the plate element by forming protrusions from a first material containing a thermoplastic material. For example, the protrusions can be formed by fusion or molding. In other words, the cavity region can be created without removing or dispensing a large amount of material, or without dispensing material at least in a loose configuration such as in the form of granules / granulated formations, pellets / balls / globules, powders or microparticles. Therefore, the manufacturing process can become more efficient and / or less time-consuming.

[0011] By having a cavity region and protrusions, a plate element with a varying thickness can be provided, which can, for example, reduce the weight of the entire plate element compared to a corresponding plate with a uniform thickness, the uniform thickness corresponding to the thickness of the plate element manufactured according to the first aspect at the location where the protrusions are located.

[0012] The formation of the protrusions can cause less tension in the plate element. Therefore, improved stability and / or improved balance characteristics can be provided.

[0013] The first material can be conformed to the forming unit, so that the shape of the formed protrusions can substantially correspond to the shape of the forming unit.

[0014] The forming and heating steps in the first aspect can be carried out in any order, or even simultaneously, preferably after the hardening step.

[0015] The cavity region can include at least one cavity, preferably a plurality of cavities. Cavities can be created near and / or between the protrusions. Throughout the present disclosure, the term "cavity" can be interpreted as a recess, groove, depression, notch, gap, incision, etc. The cavity can be open towards the back surface of the plate element.

[0016] To simplify the description herein, multiple cavities or protrusions, multiple forming elements, etc. are often mentioned, but those skilled in the art understand that at least one cavity, at least one protrusion, at least one forming element, at least one protruding element, etc. are included in these statements.

[0017] Generally herein, by hardening (or curing) the first and / or second material comprising a thermoplastic material, the first and / or second material can obtain a fixed shape. For example, the first and / or second material can be cooled to a temperature below the glass transition temperature Tg of the thermoplastic material contained therein. Cooling of the first and / or second material can provide hardening.

[0018] The substrate can be a layer of plate elements or can be hardened to form a layer such as a core. Optionally, a decorative structure such as a decorative layer and / or a wear-resistant layer can be attached, such as by lamination or adhesion, to the front side of the substrate or the core. The decorative layer can be a printed layer. In some embodiments, a backing layer such as a balancing layer can be attached, such as by lamination or adhesion, to the back side of the substrate or the core.

[0019] Optionally, the substrate or the core can include an internal section of the protrusion. Thus, the internal section of the protrusion can contain the second material, and the external section of the protrusion can contain the first material.

[0020] At least the internal region of the substrate or the core can be substantially shaped as a cuboid, optionally further including the internal section of the protrusion.

[0021] The thermoplastic material of the first and / or second material can include a thermoplastic polymer, such as polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), thermoplastic polyurethane (TPU), or polyethylene terephthalate (PET), ethylene-vinyl acetate copolymer (EVA), polyamide (PA), polystyrene (PS), polyvinyl acetate (PVAc), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), polyacrylamide (PAM), polybutylene terephthalate (PBT), or chlorinated PVC (CPVC). Generally herein, the thermoplastic material of the first and / or second material can include at least one of an amorphous polymer and a semi-crystalline polymer. The thermoplastic material of the first material can be different from or the same as the thermoplastic material of the second material.

[0022] The thermoplastic material of the first and / or second material can include a filler, preferably an inorganic filler or an organic filler. The content of the filler can exceed 40 wt%, preferably exceed 60 wt%, for example, be 50 - 90 wt% or 60 - 80 wt%.

[0023] The filler can include or can be an inorganic filler such as a mineral material, such as calcium carbonate (CaCO 3) Limestones such as chalk, talc, fly ash, barium sulfate (BaSO 4 ), or stone materials such as stone powder.

[0024] The filler may include or may be an organic filler, such as wood materials, bamboo materials, cork, or rice husks. For example, the wood material may be wood fibers and / or wood chips, and the bamboo material may be bamboo chips.

[0025] The content and / or type of the filler in the first material may be different from or the same as those in the second material.

[0026] The first material may contain functional fillers, such as cork granules, hollow microparticles such as hollow glass microspheres (glass bubbles), fibers such as organic fibers or inorganic fibers, or rubber granules. Other embodiments of the functional fillers are described in detail herein with respect to the fourth aspect, and reference is made thereto.

[0027] The amount of the thermoplastic polymer such as PVC in the first and / or second material may be 10 - 40 wt%, for example 15 - 35 wt%.

[0028] The amount of the thermoplastic material in the first material may be different from or the same as the amount of the thermoplastic material in the second material.

[0029] The core may be a rigid core. The content of the plasticizer in the core may be less than 5 wt%, preferably less than 3 wt% or less than 1 wt%, for example from 0 wt% to less than 5 wt%, or from 0.1 wt% to less than 1 wt%. The core may be free of plasticizer. The core such as a rigid core may have an elastic modulus or Young's modulus E of 1 - 10 GPa, for example 2 - 8 GPa, preferably measured according to ISO 178:2010 / A1:2013.

[0030] The core may be a flexible core. The content of the plasticizer in the core may exceed 5 wt%, preferably 5 - 15 wt%. The core such as a flexible core may have an elastic modulus or Young's modulus E of less than 2 GPa, for example 0.3 - 1.0 GPa, preferably measured according to ISO 178:2010 / A1:2013.

[0031] The first material may be heated before and / or during the shaping of the first material in the shaping unit. In some embodiments, the first material may be heated after the first material is shaped in the shaping unit.

[0032] The first material may be heated to a temperature of 80 - 295 °C. For example, the temperature of the first material may be determined by an infrared thermometer or a thermal imaging camera. The first material may be heated above the glass transition temperature Tg of the thermoplastic material of the first material. The first material may be heated below the melting temperature Tm of the thermoplastic material of the first material.

[0033] The method may include applying a first material in a forming unit or on a substrate, for example by spreading (or spraying). The method may also include applying pressure to the first material during forming and / or hardening. The pressure may be applied in a press, which preferably includes mating members. For example, the press may be a static press or a continuous press. Alternatively, the pressure may be applied by a pair of rollers, where one of the rollers may include a forming element.

[0034] The applied pressure may be in the range of 0.4 - 6.0 MPa. For example, the pressure may be the maximum applied pressure.

[0035] The method may include providing a substrate comprising a second material, the second material comprising a thermoplastic material. Preferably, the substrate has a constant thickness at least in the inner part of the substrate, but preferably has a constant thickness as a whole.

[0036] The first material may be fused (or added) to the substrate portion of the substrate by a fusing device included in the forming member. Thus, the protrusion may be formed separately from the substrate. In other words, the protrusion may be formed on the back surface. By fusing the first material to the substrate, improved stability and / or improved balance characteristics of the plate element may be provided.

[0037] The fusing of the first material may include applying heat to the first material and optionally also applying pressure. During fusing, the first material may be provided in a viscoelastic state (rubber state) and may be added and bonded or attached to the substrate portion during its hardening.

[0038] When forming the protrusion, the substrate portion, such as the entire substrate, or for example the back surface of the substrate portion, may be placed at an elevated temperature. Thus, the creation of the cavity region may become more controlled.

[0039] When forming the protrusion, the substrate portion, such as the entire substrate or for example the back surface of the substrate portion, may be provided at a temperature above the glass transition temperature Tg of the thermoplastic material / higher than the glass transition temperature. Thus, the thermoplastic material may be provided in a viscoelastic state. When the thermoplastic material includes a semi - crystalline polymer (such as PET), preferably the substrate portion is provided at a temperature below the melting temperature Tm of the thermoplastic material / lower than the melting temperature.

[0040] The method may also include raising the temperature of a substrate portion, such as the entire substrate, from an initial temperature to a raised temperature. The raised temperature may be higher than the ambient temperature at which the substrate is provided during protrusion formation and / or higher than the initial temperature of the substrate. For example, the ambient temperature may be 13 - 40 °C, such as 16 - 26 °C. The initial temperature may be the temperature of the substrate that has been adapted to the ambient temperature. Alternatively or additionally, the initial temperature may be the temperature of the substrate before heating the substrate. For example, the temperature of the substrate (portion), such as the initial temperature or the raised temperature, may be determined by an infrared thermometer or a thermal imaging camera.

[0041] The raised temperature may be obtained by heating the substrate portion. Thus, the substrate portion may be preheated before forming the protrusions.

[0042] The raised temperature may be obtained during the formation of the substrate under heating and preferably also under pressure. Thus, the heat generated for forming the substrate may be used to simplify the formation of the protrusions thereon.

[0043] The raised temperature may exceed 40 °C, preferably be 40 - 295 °C, more preferably be 100 - 295 °C. When the second material comprises PVC and preferably also comprises a filler, the raised temperature may be 50 - 210 °C, preferably 60 - 180 °C, more preferably 110 - 180 °C. When the second material comprises PP and preferably also comprises a filler, the raised temperature may be 60 - 220 °C, preferably 70 - 175 °C, more preferably 100 - 175 °C. When the second material comprises PET and preferably also comprises a filler, the raised temperature may be 70 - 295 °C, preferably 110 - 280 °C, more preferably 130 - 280 °C.

[0044] A plate element including a cavity region may be formed by hardening a first and a second material.

[0045] The act of shaping and heating the first material may be included in the act of pressing the first and second materials under heating to form the substrate and the protrusions. The first and second materials may be pressed under heating in a mold, for example, in a single pressing operation. The method may also include hardening the second material. Thus, the cavity region and the protrusions may be integrally formed with the substrate or the core as an integral piece.

[0046] A shaping member, such as a fusing device or a mold, may include a platen provided with a structured surface including the shaping unit.

[0047] The method may also include cooling the front side of the substrate during and / or after hardening of the first material. By cooling, a well-defined and uniform front side may be provided, and shrinkage of the first material may occur in the lower part / lower portion of the substrate, such as the back side. The inner part of the cavity region may constitute a non-functional surface and may serve as a compensation region for the material that shrinks during cooling.

[0048] When the forming and heating of the first material includes pressing the first and second materials under heating to form a substrate, the front side can be cooled during and / or after the hardening of the first and second materials.

[0049] As an alternative or addition to cooling the front side, the method can include cooling the lower surface of the protrusion. Thus, a well-defined and uniform portion of the back side can be provided. Preferably, the front side can be cooled at a temperature lower than the lower surface, preferably 5 - 45 °C lower, more preferably 5 - 20 °C lower.

[0050] The first and / or second material can be provided as pellets, pills, powders or microparticles. Any of these can be provided in a dry form. During heating, the pellets, pills, powders or microparticles can fuse, and the compositions within and / or between them can consolidate. Preferably, the composition of the pellets, pills, powders or microparticles has an extension length of 0.3 μm to 10 mm, for example 0.5 μm to 3 mm, in at least one direction, such as in the direction of the maximum thickness of the component, preferably in three perpendicular directions. "Composition" throughout the disclosure refers to the particles of the pellets, individual pills / pellets, grains of the powder, or particles of the microparticles. The extension length of the pellets, pills, powders or microparticles can be measured by ISO 13320:2020.

[0051] The first and second materials can be of different types, such as different types of thermoplastic materials. For example, they can differ in at least one element selected from the group consisting of polymer, grade, density, amount of filler, type of filler, amount of additive and type of additive. However, in some embodiments, the first and second materials can be of substantially the same type.

[0052] By means of the first aspect, it is easier to form the cavity region into an arbitrary shape, such as a curved or non-linear shape. This is in contrast to forming a cavity, for example, by cutting with a circular cutting blade or a saw blade. For example, a cavity with a curved or non-linear shape, such as a cavity with a waveform, can provide higher bending stiffness of the plate element.

[0053] The extension lengths of the protruding elements arranged between the forming units along a pair of non-parallel (e.g., perpendicular) horizontal directions can be substantially the same. Thus, corresponding circumscribed cavities can be formed.

[0054] The protruding elements arranged between the forming units can be elongated in the horizontal direction. Thus, elongated cavities can be formed.

[0055] The method may further include forming the substrate under heating and preferably also under pressure and / or by (co)extrusion. "(Co)extrusion" throughout the disclosure refers to extrusion (a single layer) in an extruder or coextrusion (at least two layers) in a coextruder. In the present context, an extruder or a coextruder may be referred to simply as a "(co)extruder" or sometimes just as an "extruder".

[0056] The method may further include attaching a layer to the substrate or the board element, for example by lamination or by means of an adhesive. Lamination may include laminating the layer to the substrate or the board element, optionally under heating.

[0057] The method may further include supporting the back side of the substrate or the board element during lamination of the layer to the substrate or the board element and / or during cooling of the board element (e.g., the front side), at least the inner part of the cavity including the cavity region created, and optionally supporting the lower side or the lower surface of the protrusion. PCT / SE2023 / 050596 discloses embodiments of the supporting operation on page 7, lines 11 - 20, which part is hereby expressly incorporated by reference.

[0058] The layer may be a decorative structure and / or a backing layer. Alternatively or additionally, the layer may be a sub - layer provided between the decorative structure and the core.

[0059] In some embodiments, while forming the protrusion, a layer may be attached (e.g., laminated) to the substrate.

[0060] The method may further include annealing the board element after forming the protrusion. By annealing (or "normalizing"), internal stresses in the board element, for example after creating the protrusion, can be reduced. This may be particularly important at the sharp sections or corners of the protrusion where the internal stresses may be particularly high. Annealing may be performed after heating the first material. For example, annealing may be carried out after dividing the board element into board members and before further dividing the board members into at least two panels. Thereby, the dimensional stability and / or the balance properties of the board element can be increased.

[0061] The board element may be provided in the form of panels or may be divided into at least one panel, for example at least two panels, where each panel is a building panel, a floor panel, a wall panel, a ceiling panel or a furniture part. For example, slats, slabs and tiles are all examples of panels.

[0062] The method may further include forming at least one chamfer in the cavity of the cavity region, where each chamfer is provided between the cavity wall and the back side or between the cavity wall and the bottom of the cavity.

[0063] The method may further include creating at least one conical cavity by means of at least one conical protruding element. Thus, the at least one conical protruding element may create the conical cavity. The conical protruding element may provide a draft angle. For example, the conical protruding element may include a conical side wall portion and / or an inclined surface, and the conical cavity may include a conical cavity wall and / or a chamfer. Thus, after the cavity is created, the material of the substrate can be more easily released from the protruding element. In addition, when the cavity is created, the flow of the material becomes better, especially when the substrate portion is placed at an elevated temperature.

[0064] The draft angle between the side wall portion of the at least one conical protruding element and the general normal direction of the forming member may exceed 0.5°, for example exceed 1.0° or even exceed 3.0°.

[0065] The first material may contain a plasticizer. Thus, the flow of the heated first material becomes better. For example, the plasticizer content in the first material may exceed 3 wt%, preferably 5 - 15 wt%.

[0066] According to a second aspect of the present disclosure, there is provided a panel element, such as a panel, obtainable by a method according to any embodiment of the first aspect.

[0067] According to a third aspect of the present disclosure, there is provided an apparatus for manufacturing a panel element including a cavity region, wherein the apparatus includes a forming member, such as a fusing device or a mold, which includes a forming unit.

[0068] According to a fourth aspect of the present disclosure, there is provided a panel including a back surface. The panel includes: a cavity region disposed between protrusions formed on the back surface, wherein the protrusions contain a first material containing a thermoplastic material; and a core portion containing a second material containing a thermoplastic material. Preferably, the first and second materials are of different types. However, in some embodiments, the first and second materials may be of the same type.

[0069] Thus, as will be further elaborated below, at least some panel characteristics, such as its sound characteristics, thermal characteristics, or dimensional strength, can be improved while reducing the weight of the panel.

[0070] The first and second materials may contain different types of thermoplastic materials.

[0071] The first and second materials may differ in at least one element selected from the group consisting of polymer, grade, density, amount of filler, type of filler, amount of additive, and type of additive.

[0072] The protrusions may be disposed below the lower side surface of the core portion. The lower side surface may be a substantially flat surface.

[0073] The first material may comprise functional fillers such as cork granules, hollow microparticles (such as hollow glass microspheres), fibers (such as organic or inorganic fibers), or rubber particles. The cork granules, microparticles or organic fibers may reduce the weight of the panel and / or may provide thermal insulation for the panel. In addition, the cork granules or rubber particles may provide sound damping, such as vibration absorption characteristics and / or impact damping. In addition, the cork granules or rubber particles may increase the flexibility of the first material. For example, the rubber particles may be recycled particles.

[0074] Generally, the fibers may reinforce the protrusions. Inorganic fibers may increase the strength or stiffness of the protrusions and, in some embodiments, may at least partially balance the upper layer of the panel, such as a reinforcing layer, for example to reduce its cup-shaped deformation. The inorganic fibers may be glass fibers, carbon fibers, steel fibers or combinations thereof. The organic fibers may be synthetic fibers (such as polymer fibers, polyester fibers, PP fibers, nylon fibers, aramid fibers or polyvinyl alcohol fibers), or natural fibers (such as wood fibers or fibers from rice husks, flax, hemp, bamboo, cotton, sisal, jute or ramie), or combinations thereof.

[0075] The first and / or second material may be formed from pellets, pills, powders or microparticles.

[0076] In some embodiments, the protrusions may be formed by fusing or molding, such as as described herein with respect to the first aspect.

[0077] The protrusions may be at least partially disposed below the locking means of the panel, such as at least partially directly below / immediately below the locking means of the panel. For example, the protrusions may be disposed below a strip extending horizontally from the lower portion of the panel element.

[0078] A cavity region may be provided inside the back surface. The interior may be spaced apart from a pair of opposite edge portions of the panel, such as from opposite short edge portions, optionally from all edge portions of the panel.

[0079] The panel may further include a decorative structure, such as a decorative layer and / or a wear-resistant layer.

[0080] The panel may include at least one layer. Any layer, some layers or each layer of the panel may comprise a thermoplastic material.

[0081] The extension lengths of the cavities in the cavity region along a pair of non-parallel (such as perpendicular) horizontal directions may be substantially the same.

[0082] The cavities in the cavity region may be elongated in the horizontal direction.

[0083] Additional embodiments and examples of the second, third, and fourth aspects are largely similar to the embodiments and examples of the first aspect, and reference is made thereto. For example, the panel according to the fourth aspect can be formed by fusion or molding.

[0084] In addition, the board element or panel according to any one of the first, second, third, or fourth aspects can be a luxury vinyl tile (LVT tile), a stone plastic (polymer) composite panel, or a solid polymer core board (SPC panel), or an expanded polymer core board (EPC panel), also known as a waterproof core board or a wood plastic composite panel (WPC panel).

[0085] Generally, unless otherwise clearly defined herein, all terms used in the claims and the items in the following embodiments section will be interpreted according to their ordinary meaning in the technical field. Unless otherwise clearly stated, all references to "a / the [element, device, component, mechanism, step, etc.]" shall be construed openly as referring to at least one example of the element, device, component, mechanism, step, etc. References to one or more "at least one element" etc. may be abbreviated as "element". Description of the Drawings

[0086] The present disclosure will be described in more detail below in conjunction with exemplary embodiments and with reference to the accompanying exemplary drawings, wherein:

[0087] Figure 1a-1b An embodiment of an apparatus for manufacturing a board element including a cavity region and its application is shown in a side view.

[0088] Figure 1c-1d An embodiment of a forming member and a cooling unit is shown in a side view ( Figure 1c ) and an embodiment of a board element or panel manufactured by the apparatus in any one of FIGS. Figure 1a-1b 2a - 2d, for example, is shown ( Figure 1d ).

[0089] Figure 2a-2d An embodiment of a forming member and its application is shown in a side cross-sectional view.

[0090] Figure 2e-2h An embodiment of a protruding element of the forming member is shown in a perspective view ( Figure 2e-2f ) and a related side view ( Figure 2g-2h ).

[0091] Figure 3a-3c An embodiment of an apparatus for manufacturing a board element including a cavity region and its application is shown in a side view.

[0092] Figure 4a-4bAn embodiment of an apparatus for manufacturing a plate element including a cavity region and its application is shown in a side view.

[0093] Figure 4c An embodiment of a forming member and its application are shown in a side cross-sectional view.

[0094] Figure 4d An embodiment of a composite material, for example used as the first and second materials in Figure 4b is shown in a perspective view.

[0095] Figure 5a-5f An embodiment of a forming member is shown in a perspective view ( Figure 5a ), and in a side view ( Figure 5b ). Embodiments of a forming member are shown in a perspective view ( Figure 5c ), and in a side cross-sectional view ( Figure 5d ), and a schematic embodiment of a forming member is shown in a perspective view ( Figure 5e ), and in a side view ( Figure 5f ).

[0096] Figure 6a-6c An embodiment of the interior portion of a forming platen is shown in a perspective view ( Figure 6a ), and an embodiment of a forming member and its application are shown in a side cross-sectional view ( Figure 6b-6c ).

[0097] Figure 6d-6e An embodiment of a plate element, for example manufactured from a forming member in Figure 6b-6d , is shown in a side cross-sectional view.

[0098] Figure 7a-7c An embodiment of a plate element is shown in a side cross-sectional view.

[0099] Figure 7d-7f Embodiments of a forming member and its application ( Figure 7d-7e ) and an embodiment of a substrate provided with a cavity region ( Figure 7d-7f ) are shown in a side (cross-sectional) view.

[0100] Figure 7g An embodiment of a plate element is shown in a side cross-sectional view.

[0101] Figure 8a-8e An embodiment of a plate element or panel is shown in a perspective view ( Figure 8a ), and another embodiment of a plate element or panel is shown in a top view ( Figure 8b ), a bottom view ( Figure 8c ), and a side cross-sectional view ( Figure 8d-8e ).

[0102] Figure 8f-8gAn embodiment of a plate element or panel is shown in a bottom view.

[0103] Figure 9a-9d An embodiment of a plate element or panel is shown in a bottom view ( Figure 9a ) and a side sectional view ( Figure 9b-9d ).

[0104] Figure 9e-9f A side sectional view of an embodiment of a plate element ( Figure 9e ) and a panel ( Figure 9f ) obtainable from the plate element is shown.

[0105] Figure 9g-9h An embodiment of a plate element ready to be divided into panels is shown in a side sectional view and a bottom view.

[0106] Figure 9i An embodiment of a conceivable geometry of a cavity and / or a protruding element is shown in a top view.

[0107] Figure 10a-10b A flowchart of an embodiment of a method for manufacturing a plate element is shown. DETAILED DESCRIPTION

[0108] Next, various different embodiments of a device 20 for manufacturing a plate element 1 will be described with reference to the embodiments in, for example, Figure 1a-1d , Figure 2a-2h , Figure 3a-3c , Figure 4a-4d , Figure 5a-5f , Figure 6a-6e , Figure 7a-7g , Figure 8a-8g , Figure 9a-9i and Figure 10a-10b . The plate element 1 includes a cavity region 2 in the back surface 1e of the plate element. The cavity region 2 may include at least one cavity 2', for example, a plurality of cavities 2'. The plate element 1 may be rectangular including long edge portions 1a, 1b and short edge portions 1c, 1d, but other shapes of the plate element such as square are also conceivable.

[0109] The device 20 extends in a longitudinal direction X, a transverse direction Y, and a vertical direction Z. As shown in the embodiments in Figure 1a-1c , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c , Figure 5a-5f , Figure 6a-6c and Figure 7d-7e , the device 20 includes a forming member 10 which includes at least one forming unit 11, preferably a plurality of forming units. The forming member 10 may further include a cooperating member 12. The forming member 10 is adapted to press the material between the forming unit 11 and the cooperating member 12.

[0110] In some embodiments, the protruding element 9 of the forming member 10 may be arranged adjacent to the forming unit 11 and / or between the forming units 11. The protruding element 9 may be provided on the base 10a of the forming member and may protrude from the base 10a in the general / substantially normal direction N of the base 10a. Preferably, the protruding elements 9 are separated from each other, for example, separated from each other along a horizontal direction or two mutually perpendicular horizontal directions. The pressing surface 12a of the mating member 12 may be flat and / or smooth. However, in some embodiments, the pressing surface 12a may be configured to provide embossing 6d in the front face 6b, 1g of the plate element 1 or in the base plate 6 of the plate element 1, for example, in its decorative structure 8b, see Figure 1d , Figure 2a-2b , Figure 3b , Figure 8a and Figure 8b .

[0111] As an alternative or supplement to the protruding element 9, in some embodiments, the forming unit 11 may be formed as a lower part 9f of the base 10a, for example, a recess, which extends inwardly from the base 10a (e.g., along the normal direction N), for example, inside the horizontal plane HP provided along the base 10a, see, for example, Figure 4c . This is conceivable in any of the embodiments herein, for example, in Figure 1a-1d , 2a - 2d, 3a - 3c, 4a - 4b, 5a - 5f, 6a - 6c and 7d - 7e.

[0112] In some embodiments, the forming member 10 may include a fusing device 11a configured to fuse the first material 4 to the substrate portion 6c of the substrate 6 to form a protrusion 3 thereon, see Figure 1a-1c , Figure 2a-2d , Figure 3a-3c and Figure 6b . In a number of other embodiments, the forming member 10 may include a mold 11b configured to press the first material 4 and the second material 5 under heating to integrally form the substrate 6 and the protrusion 3, see Figure 4a-4b and Figure 6c .

[0113] In some embodiments, as Figure 1a-1c , Figure 5a-5f and Figure 7d-7e shown, the forming member 10 includes at least one roller 17a (see the lower dashed line in Figure 7d-7e ), and the mating member 12 may include a mating roller 17b, and each roller is preferably rotatably arranged in the device 20. The general normal direction N may correspond to the radial direction R of the roller, preferably perpendicular to the circular base. The rollers 17a, 17b may rotate about their respective axes AX, BX.

[0114] In some embodiments, such as Figure 2a-2d , Figure 3a-3c , Figure 4a-4c and Figure 6a-6c shown, the forming unit 11 and the mating member 12 are provided in the platen assembly 13. The forming member and the mating member may respectively include a forming platen 13a and a mating plate 13b provided with a structured surface 13c. Each forming unit 11 may include a lower portion / lower part 9f of the structured surface 13c. Figure 6a Shows Figure 6b or Figure 6c the inner part of the forming platen 13a in

[0115] The side wall 13h is not shown. The structured surface 13c may include protruding elements 9 and an intermediate lower portion 9f provided therebetween, such as a recess. For example, the structured surface may be part of a corrugated plate. The overall normal direction N may be perpendicular to the base 10a, for example perpendicular to the horizontal plane HP.

[0116] Optionally, the forming unit 11 and the mating member 12 may be relatively displaced relative to each other along, for example, the vertical direction V. Figure 2a-2b and Figure 6b-6c ) or a multi-layer press (see, for example Figure 2c-2d ), or a continuous press such as a twin-belt press (see, for example Figure 3a-3c and Figure 4a-4b ). The pressing device may be a fusing device 11a or a mold 11b.

[0117] In some embodiments, the static press may include at least two forming platens 13a, and preferably at least two mating plates 13b, see, for example Figure 2c the general schematic embodiment in Figure 2d and the more specific embodiment in Figure 2d . The platen 13a may include protruding elements 9 on the base 10a, which base 10a is provided on one side 13d of the platen, see, for example Figure 2d . The opposite side 13e of the inner platen 13a may be formed as part of the mating plate 13b. The substrate 6 may be arranged face-to-back (front side to back side) in the static press.

[0118] For example, such as Figure 1a-1c , Figure 2a-2d , Figure 3a-3c , Figure 4a-4b , Figure 5a-5f and Figure 6b-6cAs shown, the first material 4 and / or the substrate 6 in which the cavity region 2 is to be created can be provided, for example fed between the forming unit 11 and the mating member 12. During the formation of the protrusions 3 in the substrate 6, the forming unit and the mating member can be configured to face the back side 6a and the front side 6b of the substrate, respectively.

[0119] The double-belt press can include an upper endless belt unit 27a and a lower endless belt unit 27b. The forming platen 13a can be provided as part of the belt of the upper endless belt unit 27a or the lower endless belt unit 27b, see for example Figure 3a and Figure 4a-4b . Further, the mating platen 13b can be provided as part of the belt of the lower endless belt unit 27b or the upper endless belt unit 27a, see for example Figure 3a-3c and 4a-4b.

[0120] In some embodiments, as Figure 3b-3c shown, a part of the platen assembly 13 can be provided independently of the double-belt press. The platen assembly 13 can include a plurality of independent forming platens 13a, for example see Figure 3b , and the independent forming platens are preferably configured to be reusable multiple times.

[0121] In some embodiments, as Figure 3c shown, the forming member 10 includes a flexible member 13f that includes protruding elements 9, and the flexible member is preferably configured to be wound around a reel 13g located, for example, upstream and / or downstream of the upper endless belt unit 27a.

[0122] The forming member 10 herein, for example in Figure 1a-1c , Figure 2a-2h , Figure 3a-3c , Figure 4a-4c , Figure 5a-5f , Figure 6a-6c and Figure 7d-7e any one of them, such as the forming platen 13a or the flexible member 13f, can include structured paper, structured sheet materials such as metal sheets or phenolic sheets, or structured foils such as polymer-based foils. The metal can include steel.

[0123] The substrate 6 can be conveyed from the inlet of the double-belt press to its pressing member 29. The pressing member 29 can include an upper pressing member 29a and / or a lower pressing member 29b, and the upper pressing member 29a and / or the lower pressing member 29b are configured to apply pressure to the first material 4 and an optional second material 5, and preferably also apply heat, for forming the protrusions 3.

[0124] In any of the embodiments herein, for example Figure 1a-1c , Figure 2a-2d , Figure 3a-3c , Figure 4a-4c , Figure 5a-5f ,Figure 6a-6c and Figure 7d-7e the protruding element 9 in Figure 7d-7e can be frustoconical or hemispherical, or can be formed into a preferred cuboid, parallelepiped, polyhedron, prismoid such as a prism, etc. Figure 2e-2h A hemispherical protruding element and a prismoid / prismatic protruding element are shown. For example, their forms can be determined relative to the base 10a.

[0125] The protruding element 9 can be conical / can be tapered, preferably tapered in a direction away from the base 10a, such as in the general normal direction N. In any embodiment herein, for example, in Figure 1a-1c , Figure 2a-2h , Figure 3a-3c , Figure 4a-4c , Figure 5a-5f , Figure 6a-6c and Figure 7d-7e in Figure 1a-1c to Figure 7d-7e , the draft angle α between the side wall portion 9c of the protruding element 9 and the general normal direction N can exceed 0.5°, for example exceed 1.0° or even exceed 3.0°, see Figure 2g-2h and Figure 7e . For example, α can be 0.5° - 70°, for example 0.5° - 45° or 1° - 30°. Figure 7d-7e The bases 10a of the forming platen 13a and the roller 17a are shown by solid lines and dashed lines respectively in Figure 7d-7e . In some embodiments, such as Figure 2e , Figure 2g , Figure 5a-5f , Figure 6a-6c and Figure 7d-7e shown, the side wall portion 9c can be substantially planar. Optionally, as Figure 2f and Figure 2h shown, the side wall portion 9c can be curved.

[0126] Other types of conical protruding elements can also be contemplated. In some embodiments, the protruding element 9 can include inclined surfaces, such as an external inclined surface 9a and / or an internal inclined surface 9b, see for example Figure 2e , Figure 2g and Figure 7d . The external inclined surface 9a can be provided between the side wall portion 9c and the outer wall 9d. The internal inclined surface 9b can be provided in the inner region 9e of the protruding element 9 adjacent to the base 10a. The inclined surfaces 9a and / or 9b can be inclined at an angle β with respect to the general normal direction N. For example, the inclined surface angle β can be 10° - 70°, for example 25° - 40°, for example 45°.

[0127] The device 20 can include a substrate forming arrangement structure 16, which is preferably provided upstream of the forming member 10, see for example Figure 1a-1b , or provided by the mold 11b, see for example Figure 4a-4b and Figure 6cThe hardened substrate 6 can provide the core 8a of the panel element 1. Optionally, the substrate 6 can include an additional layer 8, for example obtained by co-extrusion therefrom.

[0128] As shown in the embodiments of, for example Figure 1a the substrate forming arrangement 16 can include an extruder 16a (or co-extruder) and a roll assembly 16b for calendering the extrudate from the extruder. The extruder 16a can communicate with a material container 23 configured to receive, for example via a hopper, a second material 5 containing a thermoplastic material that includes a thermoplastic polymer and a filler. For example, the second material 5 can be received via the hopper.

[0129] In some embodiments, and as can be seen in, for example Figure 1b the substrate forming arrangement 16 can include a roll mill 25, preferably a two-roll mill, in communication with the material container 23, and an optional roll assembly 16b. The substrate forming arrangement 16 can also include a mixer 24, such as a Banbury mixer or a kneader, located upstream of the roll mill 25 and preferably also includes a heater 26 for heating the second material 5 received in the material container 23. The mixer 24 can include a rotatable mixing member 24a that includes, for example, at least one rotating element. Optionally, the mixer 24 and the heater 26 can be combined. In some embodiments, the heat can be provided by friction.

[0130] Figure 1a The roll assembly 16b in or 1b can include at least three rolls, such as 4, 5, or 6 rolls, which are, for example, stacked vertically on top of each other or arranged adjacent to each other in a horizontal direction. By means of the roll assembly 16b, the extrudate or the heated material (preferably in a paste form) from the roll mill 25 can be calendered into a substrate 6 in the form of a sheet, preferably a continuous sheet. The sheet thus obtains a substantially constant thickness.

[0131] The apparatus 20 can include an application device 28, such as at least one spreading device, configured to apply the first material 4 onto the substrate 6, see, for example Figure 1a-1b and 3a - 3c, or in the forming unit 11, for example on the forming platen 13a, see, for example Figure 4a-4c and 6b - 6c.

[0132] The apparatus 20 can include a heating device 14 for heating the substrate 6 and / or the first material 4. In some embodiments, as Figure 1a shown, the heating device 14 can be provided in the substrate forming arrangement 16. For example, the extrudate from the (co-)extruder can be provided at an elevated temperature TS, which is, for example, 90 - 225 °C, such as 145 - 220 °C. In some embodiments, and as Figure 1a-1bAs shown in FIGS. 3a and 3b, the heating device 14 can be a separate heating device, for example in the form of one or more heating rollers, in the form of the heater 26, or in the form of an infrared heater. In a first example, the first and second rollers and optionally the third roller in the roller assembly 16b can be heated along the feed direction F, see Figure 1a or 1b. In a second example, the roller 17a can be heated to provide the heating device 14. In some embodiments, the heating device 14 can be provided as a heating zone in a twin belt press, see Figure 3a-3c and Figure 4a-4b .

[0133] It is clear that the substrate 6 in any one of those disclosed herein, for example Figure 1a-1c , Figure 2a-2d , Figure 3a-3c , Figure 6b and Figure 7d-7f , can be provided at an elevated temperature TS, for example by means of any of the alternatives in the previous paragraphs.

[0134] Optionally, the device 20 can include a preheater 14a adapted to preheat the first material 14a, such as an infrared heater, see for example Figure 1a-1b and Figure 3a .

[0135] As an alternative or supplement to the heating device 14, the device 20 can include a cooling unit 15 and / or 15a, which is preferably arranged downstream of the heating device 14 and / or at the heating device 14. There can be a cooling unit 15 arranged upstream of the forming member 10 and / or a cooling unit 15a arranged downstream of the forming member 10 or at the forming member 10. The cooling units 15, 15a can be provided in the form of one or more heating rollers (for example see Figure 1a and Figure 1c ), can be arranged individually in the form of direct or indirect fluid cooling or in the form of air cooling (for example see Figure 1a and Figure 1b ), or can be provided in the form of a cooling zone in a twin belt press (for example see Figure 3a-3c and Figure 4a-4b ). The cooling unit 15a can be provided by the roller 17b, a cooling zone in a twin belt press and / or an optional separate cooling unit including rollers. The cooling unit 15a adapted to face the back 6a and / or the front 6b of the substrate 6 (see the dashed lines in Figure 1a and Figure 1c ) can be configured to cool the back 6a and / or the front 6b.

[0136] Optionally, the substrate forming arrangement 16 may include a top layer roll arrangement 22, which includes a decorative layer roll arrangement 22a and / or an abrasion resistant layer roll arrangement 22b. Such a top layer roll arrangement 22 is shown more schematically in Figure 1a-1b but is conceivable in any of the embodiments herein, for example in Figure 1c , Figure 3a-3c and Figure 4a-4c or in any one of Figure 1c , Figure 3a-3c and Figure 4a-4c or in relation to any one of them. Thus, the decorative structure 8b such as the decorative layer 8c and / or the abrasion resistant layer 8d may be continuously laminated onto the board element 1 after or during the formation of the board element 1. The decorative structure 8b may be applied to the substrate 6 or the board element 1 under the pressure of the rolls in the top layer roll arrangement 22, preferably without using an adhesive. Optionally, the board element 1 may be heated during lamination, for example by IR heating or by means of one or more heated rolls in the top layer roll arrangement 22 and / or in the roll assembly 16b. In some embodiments, the decorative structure 8b may be formed by directly printing, preferably digitally printing, the print P onto the board element 1 or the core 8a by means of a printing press 22c and optionally also providing an abrasion resistant layer 8d on the print P, see for example Figure 4a and Figure 8a . In some embodiments, the backing layer 8e may be laminated onto the substrate 6 or the board element 1 correspondingly before or after creating the cavity region 2.

[0137] In some embodiments, at least one layer 8 may be laminated onto the board element 1 in a pressing member 29 (such as a static press or a continuously used roll), preferably with heating during lamination, see for example Figure 1b and Figure 2a-2b . The layer 8 may be the decorative structure 8b and / or the backing layer 8e. Alternatively, the layer 8 may provide dimensional stability to the panel. For example, the layer 8 may be a mineral base layer, preferably containing magnesium oxide and optional magnesium chloride (such as MgCl 2 ) and / or magnesium sulfate (such as MgSO 4 ).

[0138] In some embodiments, as shown in Figure 1b , the apparatus 20 may further include a support member 18, which is adapted to support the back surfaces 6a, 1e, at least including the inner part 2f of the created cavity 2' and optionally the lower surface 3c of the formed protrusion 3. The cavity 2' and / or the protrusion 3 may be supported during the lamination of the layer 8 onto the substrate 6 or the board element 1 and / or during the cooling of the board element (such as the front surfaces 6b, 1g).

[0139] The support member 18 may include at least one protruding support element 7, preferably a plurality of protruding support elements. PCT / SE2023 / 050596 discloses embodiments of such a support element 18 and its operation on pages 12, lines 13 - 19, page 16, lines 20 - 26, page 20, lines 17 - 28, page 21, lines 1 - 9, and Figure 2a and Figure 6a -6i, which are hereby expressly incorporated by reference in their entirety, including the passage around the abutment member 17 and the displaceability in the direction W.

[0140] As Figure 1a-1b shown, but also conceivable in any of the embodiments herein, the device 20 may further include a plate dividing device 21a and / or a profiling unit 21b. The plate dividing device 21a may be configured to divide the plate element 1 into at least one panel 1', for example at least two panels 1'. The profiling unit 21b may be adapted to produce locking means 19a, 19b on at least one edge portion 1a, 1b, 1c, 1d of the plate element 1 in the form of a panel 1' or in the form of at least one panel 1' into which the plate element has been divided. For example, the locking means 19a and / or 19b may preferably be produced by machining on the long edge portions 1a, 1b and / or the short edge portions 1c, 1d.

[0141] As Figure 1b , Figure 1d , Figure 3a-3c , Figure 4a and Figure 8a shown, in some embodiments, the manufactured plate element 1 or panel 1' does not include locking means. For example, they may be assembled in a loose / scattered configuration, preferably abutting each other, or they may be attached to the underlying floor by an adhesive.

[0142] For example, Figure 1a-1c , Figure 2a-2h , Figure 3a-3c , Figure 4a-4c , Figure 5a-5f , Figure 6a-6c and Figure 7d-7e The device 20 in any one of is capable of implementing a method for manufacturing a plate element 1 (such as a panel) that includes a cavity region 2 in the back 1e of the plate element, the cavity region including at least one cavity 2', preferably a plurality of cavities 2'. Figure 10a and Figure 10b The flowcharts in illustrate embodiments of such a method (block 30 or 40).

[0143] The plate element 1 is made of a first material 4 and a second material 5, each of the first and second materials comprising a thermoplastic material. The first material 4 and / or the second material 5 may comprise a thermoplastic polymer (such as PVC, PE, PP, TPU, PET, EVA, PA, PS, PVAc, PMMA, PVB, PC, ABS, PAM, PBT or CPVC), fillers, and optionally additives (such as at least one of stabilizers, blowing agents or foaming agents, plasticizers, colorants, pigments, lubricants, impact modifiers, processing aids, etc.).

[0144] Additives in the first material 4 such as plasticizers and / or lubricants can help increase the flow of the material, so a more controllable fusion or molding can be obtained. Plasticizers such as dioctyl terephthalate (DOTP) can soften the first material 4. The lubricant can be an internal lubricant such as fatty alcohol or fatty glyceride, and / or an external lubricant such as wax, for example PE wax or paraffin wax. For example, the content of the plasticizer can be 1-25 wt%, preferably 3-20 wt%, and / or the content of the lubricant can be 0.2-5 wt%, preferably 1-2 wt%. In addition, additives such as processing aids can be included to improve the fusion of the second material 5 during the formation of the substrate 6 and / or to reduce the formation of cracks during fusion or molding. For example, the content of a processing aid such as an acrylic processing aid can be 0.5-5 wt%, preferably 1-3 wt%.

[0145] In some embodiments, the thermoplastic polymer of the first material 4 may comprise a PVC-PVAc copolymer and optionally also PVC. Thus, the first material 4 can become softer and easier to process, whereby fusion or molding can become simpler. For example, the content of the PVC / PVAc copolymer can be 5-100 wt%, preferably 8-25 wt%.

[0146] The composition of the first material 4 and / or the second material 5 can be provided as a mixture such as powder or particles, which are preferably provided as a dry blend before heating. The composition of the powder (or particles) can have an extension length of 0.3-200 μm, for example 0.5-50 μm (or 0.2-3.0 mm, for example 0.3-1.5 mm) in at least one direction, such as in the maximum thickness direction of the part, preferably in three perpendicular directions. Preferably, the thermoplastic material is uniformly distributed in each of the first and / or second materials. Alternatively, as Figure 4dAs shown in the embodiments herein, the first material 4 and / or the second material 5 may be provided as a composite material, preferably as a pre-composite material such as pellets, pills or microparticles, which preferably comprise a thermoplastic polymer, a filler and optionally any of the above additives. The composition of the pellets or pills may have an extension length of 0.5 - 10 mm, preferably 1 - 3 mm, in at least one direction, for example in the direction of the maximum thickness of the composition, preferably in three perpendicular directions, and the composition of the microparticles may have an extension length of 0.2 - 3.0 mm, preferably 0.3 - 1.5 mm, in at least one direction, for example in the direction of the maximum thickness of the composition, preferably in three perpendicular directions. The composite material may increase the cohesion of the first material and / or may increase the adhesion between the first and second materials. The filler in any of these alternatives may include or may be an inorganic or organic filler, such as a mineral material, such as CaCO 3 , limestone such as chalk, talc, fly ash, BaSO 4 , or stone such as stone powder. In addition, the first material 4 may comprise a functional filler, such as cork granules, hollow microparticles (such as hollow glass microspheres), fibers (such as organic or inorganic fibers), or rubber particles.

[0147] According to some embodiments, such as the embodiments implemented by the device 20 in any one of Figure 1a-1c , Figure 2a-2d , Figures 3a - 3c and Figure 6b , first, a substrate 6 comprising the second material 5 is provided (block 31) or a substrate 6 comprising the second material 5 is formed under heating and preferably also under pressure and / or preferably by (co)extrusion (block 32), the second material 5 comprising a thermoplastic material. In the former case, the substrate 6 thus provided may be pre-formed, preferably without cavities 2', and the substrate portion 6c comprising the second material 5 may optionally be heated by a heating device 14 (block 33) such that the substrate portion 6c or even the entire substrate 6 comprising the second material 5 is brought to an elevated temperature TS. On the other hand, when forming the substrate 6, the elevated temperature TS may be obtained during the formation. For example, the substrate 6 may be formed in a substrate forming arrangement 16.

[0148] The elevated temperature TS may exceed 40 °C, preferably be 40 - 295 °C, more preferably be 100 - 295 °C. When the thermoplastic material comprises PVC, the elevated temperature TS of the second material 5 may be 50 - 210 °C, preferably 60 - 180 °C, more preferably 110 - 180 °C. When the thermoplastic material comprises PP, the elevated temperature TS may be 60 - 220 °C, preferably 70 - 175 °C, more preferably 100 - 175 °C. When the thermoplastic material comprises PET, the elevated temperature TS may be 70 - 295 °C, preferably 110 - 280 °C, more preferably 130 - 280 °C.

[0149] Thereafter, the first material 4 is formed in the forming unit 11 of the forming member 10 (block 34). The first material 4, which can be provided as a mixture or composite material, can be applied by an application device 28 in a fusing device 11a including the forming unit 11 or on the substrate 6, for example, by spreading application, see Figures 1a - 1c , Figures 2a - 2d , Figures 3a - 3c , Figure 4c and Figure 6b . For example, it can be applied in the forming unit 11 and optionally between the forming units, above the protruding element 9. The first material 4 can be fused to the substrate portion 6c (block 34) by applying heat to the first material and optionally also applying pressure, for example, fusing is carried out in the fusing device 11a, see Figures 1a - 1c , Figures 2a - 2d , Figures 3a - 3c and Figure 6b . Preferably, before and / or during the forming of the first material 4, the first material 4 is heated to a temperature T1 of 80 - 295 °C (optionally including a preheating step) (blocks 33 and 34). For example, it can be heated by a heating device 14 and optionally also preheated by a preheater 14a. The applied pressure can be in the range of 0.4 - 6.0 MPa, for example, 0.5 - 5.0 MPa or 0.6 - 3.0 MPa. For example, the applied pressure can be 0.7 - 2.5 MPa, for example, 1.0 - 2.0 MPa. The formed first material 4 is then hardened, optionally hardened under pressure (block 35), to form a protrusion 3 fused to the back surface 6a of the substrate 6. The protrusion 3 can thus be formed on the back surface 6a. The substrate 6 can be cooled by a cooling unit 15a and / or can be hardened to form a core 8a.

[0150] In view of the above, a plate element 1 can be obtained, which includes a cavity region 2 preferably created horizontally between the protrusions 3, see for example Figures 1a - 1c , Figures 2a - 2d , Figures 3a - 3c , Figure 6d , Figures 7a - 7b and Figure 7g .

[0151] According to some embodiments, the substrate 6 and the protrusion 3 can be formed simultaneously, preferably as a continuous layer. The first material 4 and the second material 5 can each be provided as a mixture or composite material (see above), and can be applied by an application device 28, for example, by spreading application, into a mold 11b including the forming unit 11, see Figures 4a - 4b and Figure 6cPreferably, the first material 4 and the second material 5 are respectively applied in the forming unit 11 and the mold body 11c. The mold body 11c can be arranged between the protruding element 9 and the mating member 12, for example, vertically above the protruding element 9 and vertically below the mating member 12, and can be configured to mold the core 8a of the panel element 1 or the panel 1'. The first material 4 and the second material 5 can be molded under pressure and heat (block 41), for example, molded in a pressing device. Therefore, the molding can include the forming, heating, and pressing of the first material 4 and the second material 5. Before and / or during molding, the materials 4, 5 can be heated, preferably to a temperature T1, T2 in the range of 80 - 295 °C. The applied pressure can be in the range of 0.4 - 6.0 MPa, such as 0.5 - 5.0 MPa or 0.6 - 3.0 MPa. For example, the applied pressure can be 0.7 - 2.5 MPa, such as 1.0 - 2.0 MPa. The molded first material 4 and second material 5 are then hardened (block 42), optionally hardened under pressure, to integrally form the substrate 6 and the protrusions 3 in its back surface 6a. The substrate 6 and the protrusions can be cooled by the cooling unit 15a and / or can be hardened to form the core 8a.

[0152] In view of the above, a panel element 1 including a cavity region 2 created between the protrusions 3 can be obtained, see for example Figure 4a 、 Figure 6e 、 Figure 7c and Figure 7g 。

[0153] Optionally, during the formation of the protrusions 3, the substrate 6 can be displaced in the feed direction F, see for example Figures 1a - 1c 、 Figures 3a - 3c and Figures 4a - 4b 。For example, the substrate can be fed along the longitudinal direction X and / or the vertical direction Z.

[0154] When the first material 4 contains PVC and preferably also contains fillers, it can be heated to 80 - 210 °C, preferably 100 - 180 °C. When the first material 4 contains PP and preferably also contains fillers, it can be heated to 80 - 220 °C, preferably 90 - 175 °C. When the first material 4 contains PET and preferably also contains fillers, it can be heated to 90 - 295 °C, preferably 120 - 280 °C. It should be emphasized that in the case of fusion (T1) for the first material 4, and in the case of molding (T1 and / or T2) for the first material 4 and / or the second material 5, any of these temperatures are conceivable.

[0155] In some embodiments, the fused or molded first material 4 and the second material 5 can be of the same or substantially the same type. The materials 4, 5 can have substantially the same grade, density, amount and type of filler, amount and type of additive. For example, the first and second materials can be the same. Thus, the bonding between the protrusion 3 and the substrate 6 can be improved.

[0156] In some embodiments, the fused or molded first material 4 and second material 5 may be of different types. In one example related to fusion, a first material 4 of a type different from the material type of the substrate 6 may be fused to the substrate portion 6c. In one example related to molding, the first material 4 and second material 5 may be applied such as dispersed in the forming unit 11 and the mold body 11c, respectively. For example, the forming unit 11 and the mold body 11c may contain 10-100wt%, preferably 50-100wt%, and more preferably 70-100wt% of the first material 4 and the second material 5, respectively, wherein the remaining portions of the forming unit and the mold body are composed of the second material 5 and the first material 4, respectively.

[0157] For example, the materials 4, 5 may differ in at least one element selected from the group consisting of polymer, grade, density, amount of filler, type of filler, amount of additive and type of additive. Thus, the properties of the protrusion 3 and the substrate 6 may be different, and the properties of the plate element 1 as a whole may be adapted to the environment in which it is installed. It is emphasized that in some embodiments, the thermoplastic materials of the first and second materials may be based on the same polymer, such as PVC, but may differ in at least one element selected from the group consisting of grade, density, amount of filler, type of filler, amount of additive and type of additive. For example, the first material 4 may contain functional fillers, such as cork particles, hollow microparticles (such as hollow glass microspheres), fibers (such as organic fibers or inorganic fibers), or rubber particles.

[0158] In some embodiments, the substrate 6 may be cooled (block 36 or 43). In particular, the front side 6b of the substrate 6 may be cooled during and / or after hardening of the first material 4, preferably by a cooling unit 15a adapted to face the front side 6b, see e.g. Figures 1a - 1c , Figures 3a - 3c and Figures 4a - 4b . Thus, a hard shell layer may be provided.

[0159] Alternatively or additionally, the back side 6a of the protrusion 3, preferably the lower side 3c, may be cooled. The lower side 3c may be part of the lowest part of the back side 6a. For example, a heating device 14 and a cooling unit 15a provided by rollers 17a and 17b, respectively, may be used, see Figure 1aAlternatively or additionally, a cooling unit 15a suitable for the back side 6a can be used. When both the back side 6a and the front side 6b are cooled, the front side 6b is preferably cooled more than the lower surface 3c. Preferably, the inner part 2f of the cavity 2' is not directly cooled. In some embodiments, the entire substrate 6 including the front side 6b and the lower surface 3c can be cooled.

[0160] In some embodiments, the method can include forming at least one chamfer 2a, 2b in the cavity 2'. The chamfers, such as the outer chamfer 2a and / or the inner chamfer 2b, can be formed by the inclined surfaces of the protruding element 9, such as the inner inclined surface 9b and / or the outer inclined surface 9a. The chamfers 2a, 2b can be arranged along the longitudinal extension length LE and / or the transverse extension length TE of the cavity 2' (see Figures 8f - 8g and Figure 9a ), for example, arranged along the entire circumference 2j of the cavity. Each chamfer 2a, 2b can be arranged between the cavity wall 2c and the back sides 6a, 1e, or between the cavity wall 2c and the bottom wall 2d of the cavity 2'. The chamfers 2a, 2b can be inclined at a chamfer angle γ with respect to the normal direction M of the substrate 6 or the plate element 1, see for example Figure 7d and Figure 7f . The chamfer angle γ can be 10 - 70°, for example 25 - 40°, for example 45°. The inclined surfaces 9a, 9b and / or the chamfers 2a, 2b can be substantially planar (see Figure 7d ) or rounded (see the dashed line at 9a in Figure 7f and Figure 7d ), for example, including a radius RB. The extension length of the substantially flat inclined surface and / or the substantially flat chamfer can be 0.07 - 2 mm, for example 0.1 - 1 mm. For the rounded inclined surface or the rounded chamfer, the radius RB can be 0.05 - 2.5 mm, for example 0.1 - 1.2 mm.

[0161] More generally, the method can include creating a tapered cavity 2' by means of a tapered protruding element 9, see for example Figure 7e . The cavities 2' can taper along their longitudinal extension length LE and / or their transverse extension length TE. The cavity wall 2c can be inclined at a wall angle δ with respect to the normal direction M, see for example Figure 7e . The wall angle δ can exceed 0.5°, for example exceed 1.0° or even exceed 3.0°. Alternatively or additionally, the wall angle δ can be less than 80°, for example less than 70°, or even less than 50°. For example, the wall angle δ can be 0.5 - 70°, for example 0.5 - 45° or 1 - 30°. As an alternative or supplement to the tapered cavity wall 2c, the tapered cavity 2' can include the above-mentioned chamfers 2a, 2b.

[0162] Generally, herein, the form / shape of the cavity 2' may correspond to the form / shape of the protruding element 9. For example, the draft angle α and the wall angle δ may correspond to each other, and / or the bevel angle β and the chamfer angle γ may correspond to each other.

[0163] Optionally, the layer 8 may be attached (e.g., laminated or adhered) to the substrate 6 or the plate element 1 (frame 37 or 44), see for example Figures 1a - 1b 、 Figure 2a 、 Figure 2d and Figures 6b - 6c 。In some embodiments, as Figure 1b shown, while forming the protrusion 3 and thus creating the cavity region 2, the layer 8 may be attached to the substrate 6. The layer 8 may be a decorative structure 8b, such as a decorative layer 8c and / or a wear-resistant layer 8d, and / or a backing layer 8e, see for example Figures 6d - 6e 、 Figures 7a - 7c 、 Figure 7g 、 Figures 8a - 8e and Figures 9b - 9f 。Optionally, the back sides 6a, 1e may be supported during the attachment of the layer 8 to the substrate 6 or the plate element 1, at least including the inner part 2f of the created cavity 2' and optionally the lower surface 3c of the formed protrusion 3, see Figure 1b herein and Figure 2a and Figure 6a -6h of PCT / SE2023 / 050596 referred to above.

[0164] As an alternative or supplement to supporting the back sides 6a, 1e during the attachment of the layer 8, the substrate part 6c or the plate element 1 may be cooled after creating the cavity region 2 and before attaching the layer 8, see for example Figure 2a in PCT / SE2023 / 050596 mentioned above.

[0165] The plate element 1 here may be provided in the form of a panel 1' or may be divided into at least one panel 1', such as at least two panels, where each panel is a building panel, a floor panel, a wall panel, a ceiling panel or a furniture part. In fact, embodiments of the method disclosed herein (see for example frame 30 or 40) may also include dividing the plate element 1 into at least one panel, such as at least two panels 1', by a plate dividing device 21a, see Figures 1a - 1b 。For example, the plate element 1 may be divided into plate members 1” by a first dividing unit 21a', and the plate members 1” may be further divided into at least two panels 1' by a second dividing unit 21a”, where the panels are preferably divided into substantially final forms. Preferably, the plate element 1 or the plate member 1” is divided at a temperature higher than the initial temperature of the substrate 6 and / or the ambient temperature.

[0166] Alternatively or additionally, the method may further include generating locking devices 19a, 19b on at least one of the edge portions 1a, 1b, 1c, 1d by means of a profiling unit 21b. The locking devices 19a, 19b may be configured to lock the edge portions horizontally and / or vertically to the edge portions of an adjacent panel 1'. Preferably, the locking devices 19a, 19b are formed on two opposite edge portions of the panel 1'. As Figures 9e - 9g shown, the locking devices 19a and / or 19b may be generated in the panel 1' including the cavity region 2 and the protrusion 3 by removing the material 1h of the plate, for example, by machining to remove the material 1h of the plate.

[0167] In some embodiments, as Figures 9g - 9h shown, the plate element 1 may include a protrusion 3 extending at a split portion VD of the plate element, at which split portion VD the plate element is adapted to be split into a first panel and a second panel 1'. Thus, before splitting, a single protrusion 3 may extend below both of the edge portions 1a, 1b of the first and second panels, such that the single protrusion 3 may be split into two protrusions 3 after splitting, and the two protrusions 3 are arranged below the respective edge portions 1a, 1b. Preferably, the protrusion 3 extends from a region A1 of the first panel below the strip 19c to be generated to a region A2 inside horizontally of the horizontally innermost portion 19e of the locking device 19a to be generated of the second panel. After splitting the plate element, the locking device 19a may be generated at the edge portions 1a, 1b of the first and second panels by removing the material 1h of the plate, for example, by machining to remove the material 1h of the plate. Thereby, the first and second panels 1' having the edge portions 1a, 1b as in Figure 9f can be obtained.

[0168] Figures 9e - 9h The long edge portions 1a, 1b are shown, but it should be emphasized that a similar splitting process can equally be envisaged for splitting the plate element 1 and generating the locking device 1b at the short edge portions 1c, 1d of the panel 1', see Figures 8b - 8c , Figures 8e - 8g and Figure 9d (having a strip 19c' and a horizontally innermost portion 19f).

[0169] In some embodiments, the apparatus 20 may further include an annealing unit 21c, which is preferably arranged after at least a part of the plate splitting device 21a and before the profiling unit 21b, see for example Figures 1a - 1b . In a non-limiting example, as Figure 1a most clearly seen in, the annealing unit 21c may be arranged after the first splitting unit 21a' and before the second splitting unit 21a". The annealing is preferably carried out after cooling when the substrate 6 is cooled by the cooling units 15, 15a.

[0170] Thus, after the protrusions 3 are formed, the plate element 1 can optionally be annealed (block 38 or 45). Annealing can include heating the plate element 1 or the plate member 1" to an annealing temperature of 80 - 170 °C, such as 120 - 145 °C, such as 130 - 140 °C. For example, the annealing temperature can be lower than the glass transition temperature Tg of the first material and the second material. For example, the first material 4 and the optional second material 5 can comprise PVC and a filler, such as an inorganic filler. By way of example, the annealing unit 21c can include at least one of a heating furnace, a hot air heater, and a hot bath containing a fluid (such as water).

[0171] Figure 1d , Figures 3a - 3c , Figure 4a , Figures 6d - 6e , Figures 7a - 7c , Figures 7f - 7g , Figures 8a - 8g and Figures 9a - 9i shows an embodiment of the plate element 1 such as the panel 1', which can be obtained by the methods described herein, for example by fusion or molding. The plate element 1 or the panel 1' includes at least one layer 8 such as a core 8a containing the second material 5 and a cavity region 2 disposed between protrusions 3 formed in the back surface 1e, wherein the protrusions contain the first material 4.

[0172] The protrusions 3 can be disposed below the lower side surface 8g of the core 8a (or the substrate 6). For example, the protrusions 3 can protrude vertically downward from the lower side surface 8g. The core 8a (or the substrate 6) and the protrusions 3 can extend above and below the horizontal plane H1, respectively. Thus, the first material 4 and the second material 5 can share an attachment region 50 and / or can be bonded along the attachment region 50, preferably along the horizontal plane H1. For example, at least the inner region 51 of the substrate 6 or the core 8a of the plate element 1 or the panel 1' can be shaped to be substantially cuboid, see for example Figures 6d - 6e , Figures 7a - 7c , Figures 8d - 8e and Figures 9b - 9g , optionally further including an inner section 3d of the protrusion 3, see for example Figure 7g . The inner region 51 can be disposed between the horizontal plane H1 and the front surface 6b of the core (or the substrate), and for the panel 1', it can also preferably be disposed between the horizontal innermost parts 19e and / or 19f. The horizontal plane H1 can extend along the lower side surface 8g of the core 8a (or the substrate 6) and can be a substantially flat surface. The horizontal plane H1 can be parallel to the front surface 6a and / or the back surface 6b.

[0173] In Figure 7g , the inner section 3d of the protrusion contains the second material 5 and the outer section 3e of the protrusion contains the first material 4.

[0174] Generally, the board element 1 or the panel 1' can be multi-layered, for example, obtained by co-extrusion or by attaching (e.g., laminating) the layer 8 to the core 8a. For example, the board element or the panel can include a core 8a and a decorative structure 8b, such as a decorative layer 8c and / or a wear-resistant layer 8d. The decorative layer and / or the wear-resistant layer can be provided as a thermoplastic-based foil or film, for example, including PVC. The thickness of the decorative layer and the wear-resistant layer can be 0.01 - 0.10 mm and 0.05 - 2.0 mm, respectively. In some embodiments, the decorative structure 8b can include embossing 6d, see Figures 8a - 8b . Optionally, the panel can also include a backing layer 8e and / or a covering layer 8f, such as a foam layer.

[0175] The first material 4 and / or the second material 5 and thus any, some, or each of the layers 8, 8a, 8b, 8c, 8d, 8e, 8f can contain a thermoplastic polymer and fillers. The thermoplastic polymer can be, for example, PVC, PE, PP, TPU, PET, EVA, PA, PS, PVAc, PMMA, PVB, PC, ABS, PAM, PBT, or CPVC. For example, the fillers can include or can be inorganic fillers, such as mineral materials, or functional fillers, such as cork granules, hollow microparticles, fibers such as organic fibers or inorganic fibers, or rubber granules. Particles such as glass bubbles can include at least one selected from the group consisting of silica, alumina, soda-lime, borosilicate, soda-lime borosilicate, and zirconia. Each particle can have an extension length of 5 - 200 μm, for example, 10 - 100 μm, in at least one direction of the particle, for example, in its three perpendicular directions. Generally herein, the first material 4 and / or the second material 5 can also contain additives, such as at least one of stabilizers, blowing agents or foaming agents, plasticizers, colorants, pigments, lubricants, impact modifiers, processing aids, etc. For example, the layer 8 of the panel 1 such as the core 8a, which can be obtained, for example, by an embodiment of the method described herein, can contain 10 - 40 wt% of PVC, 50 - 90 wt% of an inorganic filler such as chalk, and 0 - 20 wt%, such as 5 - 20 wt%, of additives.

[0176] In any embodiment of the substrate 6 or the board element 1 (e.g., the panel 1') herein, the surface of the inner part 2f of the cavity 2 (e.g., the cavity wall 2c and / or the bottom wall 2d) can be closed. Such a closed surface is defined on page 31, line 20 to page 32, line 2 of PCT / SE2023 / 050596, and these parts are hereby expressly incorporated by reference.

[0177] In some embodiments, as Figures 8c - 8g and Figures 9d - 9gAs shown, the cavity region 2 can be arranged inside the interior 1f of the back surface 1e, whereby the cavity 2' can be spaced apart from a pair of opposite long edge portions 1a, 1b and / or a pair of opposite short edge portions 1c, 1d. Optionally, they can be spaced apart from all the edge portions of the panel, as Figures 8c - 8g shown. The cavity 2' can be arranged inside the locking devices 19a and / or 19b, as Figures 8c - 8g and Figure 9a shown. For example, the cavity 2' can be arranged inside the horizontally innermost portions 19e, 19f of the locking devices 19a and / or 19b.

[0178] The protrusion 3 can be arranged at least partially below the locking devices 19a and / or 19b. In particular, the protrusion 3 can be arranged below strips 19c, 19c' that horizontally extend from the lower part of the plate element 1 or the panel 1', preferably directly vertically below / immediately below the strips 19c, 19c', which strips are arranged, for example, on the long edge portion 1a and / or the short edge portion 1c. The locking elements 19d, 19d' can be arranged on the strips 19c and / or 19c' and can be configured to cooperate with the locking grooves 19g and / or 19g' of an adjacent panel 1' for horizontal locking. The protrusion 3 can be arranged below the locking surfaces 19h, 19h' of the locking elements 19d, 19d', preferably directly vertically below / immediately below the locking surfaces 19h, 19h'. For example, the protrusion 3 can extend along substantially the entire strips 19c, 19c', for example, at least up to the horizontally innermost portions 19e, 19f, see for example Figures 8c - 8e .

[0179] In some embodiments, the protrusions 3 can be at least partially separated from each other. In some embodiments, as Figure 7a and 7g shown, the protrusions 3 can be completely separated from each other (discontinuous), for example, completely separated from each other (discontinuous) along one direction or along two perpendicular directions. In Figure 7a , the protrusion 3 can extend vertically to the horizontal plane H1, while in Figure 7g , the protrusion 3 can extend vertically below the bottom wall 2d of the cavity 2'.

[0180] In some embodiments, as Figures 6d - 6e and Figures 7b - 7cAs shown, for example, an intermediate part 3b, which can be a strip or a film, can extend between the protrusions 3, for example, between their inner sections 3d. The thickness K of the intermediate part 3b can be 0.1 - 3.0 mm, for example, 0.3 - 2.0 mm. For example, a pair of adjacent protrusions 3 can be continuously connected to each other through the intermediate part 3b. The surface of the intermediate part 3b can include the inner part 2f of the cavity 2'. In some embodiments, the intermediate part 3b together with the region 3a provided above the protrusion 3 can form the entire substrate 6 or the core 8a, see, for example Figure 6e and Figure 7c .

[0181] As Figures 2e - 2h 、 Figures 5a - 5d 、 Figures 6a - 6c and Figure 9i shown, the extension lengths of the protruding element 9 along a pair of non - parallel (e.g., perpendicular) horizontal directions E1, E2 can be substantially the same. Generally here, the horizontal extension lengths E1, E2 can be determined at the bottom of the protruding element. Thus, an inscribed / circumscribed cavity 2' can be created, which has extension lengths along a pair of non - parallel, e.g., perpendicular, horizontal directions D1, D2 that are substantially the same. For example, the cavity 2' can have a circular or preferably a regular convex polygon boundary, such as the boundary of a triangle, square, pentagon, hexagon, etc., see Figures 8c - 8e 、 Figures 9b - 9d and Figure 9i . During shaping, the horizontal direction / horizontal extension lengths E1, E2 can have components along the X and Y directions.

[0182] As Figures 5e - 5f shown, in some embodiments, the protruding element 9 can be horizontally elongated, whereby a horizontally elongated cavity 2' can be created, see, for example Figures 8f - 8g 、 Figure 9a and Figure 9g . Thus, the protruding element 9 and the cavity 2' can have a longitudinal extension length LE greater than the lateral extension length TE. The elongated protruding element 9 can be arranged along a part of the base 10a, for example, along its circumference, see Figure 5f . As Figures 8f - 8g and Figure 9h shown, the elongated cavity 2' can be substantially straight, or can have a curved or non - linear shape, such as a waveform, see Figure 9a . The elongated cavity 2' can be substantially parallel to the long edge parts 1a, 1b. For example, the longitudinal extension length of the cavity 2' can be parallel to the long edge parts 1a, 1b or the short edge parts 1c, 1d. In any of the embodiments herein, the elongated cavity 2' can be continuous, for example, as Figure 8f 、 Figure 9a and Figure 9g shown, or can be discontinuous, for example, as Figure 8g shown.

[0183] Generally in the present text, for example in Figures 5e - 5f , Figures 6d - 6e , Figures 7a - 7c , Figure 7g , Figures 8f - 8g and Figures 9a - 9h , the ratio between the longitudinal extension length LE and the transverse extension length TE of the slender cavity 2' and / or the slender protruding element 9 can be 1 < LE / TE ≤ 150, for example 6 ≤ LE / TE ≤ 120, preferably 10 ≤ LE / TE ≤ 100. For the protruding element, TE and LE can be measured along the base 10c, for example along the circumference (see Figure 5f ).

[0184] For example in Figures 6d - 6e , Figures 7a - 7c , Figure 7g , Figures 8a - 8g and Figures 9a - 9i , the cavity 2' in any one of them may include at least one chamfer 2a, 2b, as has been described in detail elsewhere in this text. Figure 7d and Figure 7f show examples of such chamfers provided along the longitudinal extension length LE and / or the transverse extension length TE. For example, the chamfer in the slender cavity 2' can be provided along its longitudinal extension length LE and, optionally, along its transverse extension length TE. The chamfer can sometimes be provided along the entire circumference 2j of the cavity 2, see for example Figure 8c and Figure 8f and see also Figures 2e - 2h .

[0185] Alternatively or additionally, Figures 6d - 6e , Figures 7a - 7c , Figure 7g , Figures 8a - 8g and Figures 9a - 9i , the cavity 2' in any one of them can be conical, as detailed elsewhere in this text. In Figure 7e , Figures 8d - 8e and Figures 9b - 9g , examples of such conical cavities including inclined cavity walls 2c along the longitudinal extension length LE and / or the transverse extension length TE are most clearly shown.

[0186] Generally, the substrate 6, the core 8a or the plate element 1 such as the panel 1' in this text can have a thickness T of 2 - 10 mm, preferably the maximum thickness. In addition, the depth DC of the cavity 2', preferably most (i.e., greater than 50%) of the depth DC, can be 10 - 65% of the thickness T, for example 20 - 50%.

[0187] In some embodiments, the depth DC of the cavity 2' at the long edge portions 1a, 1b and / or the short edge portions 1c, 1d, for example at the locking devices 19a and / or 19b, may be smaller than the depth DC at the inner portion 1f, see Figures 9c - 9d For example, they may taper towards the edge portions. Thus, the locking device may become stronger and / or a more rigid plate element section may be provided.

[0188] In any of the embodiments herein, for example in Figures 1a - 1d , Figures 2a - 2d , Figures 3a - 3c , Figures 4a - 4d , Figures 6b - 6e , Figures 7a - 7g , Figures 8a - 8g and Figures 9a - 9i In the embodiment, the first material 4 and the second material 5 may be of substantially the same type. Figure 9b and Figures 9e - 9g As shown, it is contemplated that in any of the embodiments listed above, the first material 4 and the second material 5 may be of different types.

[0189] Typically, in this article, e.g. Figures 6d - 6e , Figures 7a - 7c , Figure 7g , Figures 8a - 8g and Figures 9a - 9f At least half of the cavities 2', preferably all of the cavities, provided in the rear side le may have substantially the same area AC. The area AC may be specified along a horizontal plane Q extending along the rear side le.

[0190] Aspects of the present disclosure have been described above mainly with reference to several embodiments. However, as will be readily appreciated by those skilled in the art, other embodiments than those disclosed above are equally possible within the scope of the present disclosure. For example, injection molding is included in the concept of molding / molding herein. For example, first and second materials 4, 5, which are preferably of the same type, may be injection molded to form the substrate 6 and the protrusion 3. Furthermore, it is clear that Figures 1a - 1c , Figures 2a - 2d , Figures 3a - 3c and Figures 4a - 4c The device 20 in the figure is exemplary and it is also conceivable that elements thereof, such as the preheater 14a or the coolers 15, 15a, may sometimes be removed in other embodiments.

[0191] Example

[0192] Similar to Figure 2aThe schematic diagram in [description] tests the formation of protrusions by fusion by applying a first material among and between the forming units of the forming platen. A release spray is applied among and between the forming units, and a release foil is arranged on the pressing surface of the mating member. In the first set of tests, the first material is provided as a dry blend of powders, and in the second set of tests, the first material is provided as pre-compounded pellets, which are ground from extruded pellets / pills formed from the same powder dry blend as the first set. The dry blend contains PVC powder with an average particle size of 500 nanometers and chalk with an average particle size of 20 micrometers, and also contains stabilizers, internal and external lubricants, impact modifiers, and processing aids. In the first set (or the second set) of tests, the first material is preheated with the forming platen for 10 minutes until they reach a temperature of 180 - 200 °C (or 160 - 200 °C). The first material and the sample of the SPC panel are then pressed in a static hot - hot press at a pressure of 2 - 3 MPa for 5 minutes (or 2 - 5 minutes). Then, for both the first set and the second set, samples with Figure 7b protrusions of the same formed type as shown are obtained, and the samples are passively cooled to room temperature.

[0193] It is found that the protrusions and the intermediate parts in the second set of tests are more cohesive than those in the first set of tests. In addition, it is found that the adhesion of the protrusions and the intermediate parts to the sample in the second set is stronger than that in the first set.

[0194] Embodiments

[0195] Other aspects of the present disclosure are provided below. The embodiments, examples, etc. of these aspects are largely similar to the above - mentioned embodiments, examples, etc., and thus reference the above - detailed description.

[0196] Item 1. A panel (1') including a back surface (1e), the panel comprising:

[0197] A cavity region (2) disposed between protrusions (3) formed in the back surface (1e), the protrusions comprising a first material (4) containing a thermoplastic material; and

[0198] A core part (8a) containing a second material (5) containing a thermoplastic material,

[0199] wherein the first material (4) and the second material (5) are preferably of different types.

[0200] Item 2. The panel according to Item 1, wherein the first material (4) and the second material (5) comprise different types of thermoplastic materials.

[0201] Item 3. The panel according to Item 1 or 2, wherein the first material (4) and the second material (5) differ in at least one element selected from the group consisting of polymer, grade, density, amount of filler, type of filler, amount of additive, and type of additive.

[0202] Item 4. The panel according to any one of the preceding items, wherein the protrusion (3) is provided below the lower side surface (8g) of the core portion (8a), and the lower side surface is a substantially flat surface.

[0203] Item 5. The panel according to any one of the preceding items, wherein the first material (4) contains a functional filler, such as cork granules, hollow microparticles, fibers, or rubber particles, and the fibers are, for example, organic fibers or inorganic fibers.

[0204] Item 6. The panel according to any one of the preceding items, wherein the first material (4) and / or the second material (5) is formed of pellets, pills, powders, or microparticles.

[0205] Item 7. The panel according to any one of the preceding items, wherein the protrusion (3) is formed by fusion or molding.

[0206] Item 8. The panel according to any one of the preceding items, wherein the protrusion (3) is at least partially disposed below the locking means (19a, 19b) of the panel (1').

[0207] Item 9. The panel according to any one of the preceding items, wherein the cavity region (2) is provided inside the back surface (1e), and is spaced apart from a pair of opposite edge portions (1a, 1b; 1c, 1d) of the panel, such as opposite short edge portions, and optionally spaced apart from all edge portions of the panel.

[0208] Item 10. The panel according to any one of the preceding items, further comprising a decorative structure (8b), such as a decorative layer (8c) and / or a wear-resistant layer (8d).

[0209] Item 11. The panel according to any one of the preceding items, wherein any layer (8; 8a, 8b, 8c, 8d, 8e, 8f), some layers, or each layer of the panel contains a thermoplastic material (4).

[0210] Item 12. The panel according to any one of the preceding items, wherein the extension lengths of the cavities (2') in the cavity region (2) along a pair of non-parallel, for example, a pair of perpendicular horizontal directions (D1; D2) are substantially the same.

[0211] Panel according to any one of the preceding items, wherein the cavity (2’) in the cavity region (2) is elongated in the horizontal direction.

[0212] Panel according to any one of the preceding items, wherein the first material (4) and the second material (5) are of the same type.

Claims

1. A method for manufacturing a plate element (1) comprising a thermoplastic material, the back surface (1e) of the plate element (1) including a cavity region (2), wherein the method comprises: forming a first material (4) in a forming unit (11) of a forming member (10), the first material comprising a thermoplastic material; heating the first material (4); and hardening the formed first material (4) to form a plurality of protrusions (3) in the back surface (6a) of a substrate (6), wherein the substrate comprises a second material (5), the second material comprising a thermoplastic material, thereby obtaining a plate element (1), the plate element (1) including the cavity region (2) created between the plurality of protrusions (3), wherein the first material (4) and / or the second material (5) is provided in the form of pellets, pills, powders or microparticles.

2. The method according to claim 1, wherein, the first material (4) is heated to a temperature (T1) of 80 - 295 °C.

3. The method according to claim 1 or 2, further comprising applying pressure to the first material (4) during the forming and / or during the hardening.

4. The method according to claim 3, wherein, the applied pressure is in the range of 0.4 - 6.0 MPa.

5. The method according to any one of the preceding claims, wherein, the first material (4) is fused to a substrate portion (6c) of the substrate (6) by a fusing device (11a), the fusing device (11a) being included as part of the forming member (10).

6. The method according to any one of the preceding claims, wherein, the act of forming and heating the first material (4) is included in the act of pressing the first material and the second material (4; 5) under heating conditions to form the substrate (6) and the protrusions (3), and wherein the method further comprises hardening the second material (5).

7. The method according to any one of the preceding claims, wherein, the forming member (10) such as a fusing device (11a) or a mold (11b) includes a forming platen (13a), the forming platen being provided with a structured surface (12c) including the forming unit (11).

8. The method according to any one of the preceding claims, further comprising cooling the front surface (6b) of the substrate (6) during and / or after the hardening of the first material (4).

9. The method according to any one of the preceding claims, including cooling the lower surface (3c) of the protrusions (3).

10. The method according to any one of the preceding claims, wherein, the composition of the pellets, pills, powders or microparticles has an extension length of 0.3 μm to 10 mm, for example 0.5 μm to 3 mm, in at least one direction of the composition.

11. The method according to any one of the preceding claims, wherein, the extension lengths of the protruding elements (9) arranged between the forming units (11) are substantially the same along a pair of non - parallel, for example a pair of perpendicular, horizontal directions (E1; E2).

12. The method according to any one of the preceding claims, wherein, the protruding element (9) arranged between the shaping units (11) is elongated in the horizontal direction.

13. The method according to any one of the preceding claims, further comprising forming the substrate (6) under heating conditions, preferably also under pressure conditions and / or by extrusion or co-extrusion.

14. The method according to any one of the preceding claims, further comprising attaching a layer (8) to the plate element (1).

15. The method according to any one of the preceding claims, further comprising annealing the plate element (1) after forming the protrusions (3).

16. The method according to any one of the preceding claims, wherein, the first material (4) contains a plasticizer.

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