CN113389343A

CN113389343A - Panel and method for manufacturing a panel

Info

Publication number: CN113389343A
Application number: CN202010646449.0A
Authority: CN
Inventors: 托马斯·卢克·马丁·贝尔特; 汤姆·范·波尔; 斯万·伯恩
Original assignee: Chinafloors Timber China Co ltd
Current assignee: Chinafloors Timber China Co ltd
Priority date: 2020-03-13
Filing date: 2020-07-07
Publication date: 2021-09-14
Also published as: NL2025119B1

Abstract

The present invention relates to a panel for constructing a floor or wall covering. The panel comprises a substantially flat top surface, at least one core layer of composite material, wherein the core layer is provided with at least one cavity, and a bottom surface. The panels further comprise at least one pair of opposite edges, preferably comprising complementary coupling portions configured for mutual coupling of adjacent panels.

Description

Panel and method for manufacturing a panel

Technical Field

The invention relates to a panel, in particular a floor panel, a wall panel or a ceiling panel. The invention also relates to a method of manufacturing such a panel.

Background

Over the past years, there has been a significant growth in the rigid floating floor market, moving from flexible vinyl slats or LVT (luxury vinyl tiles) to thick, rigid engineered hybrid products, integrating multiple layers; these products have several benefits, such as unprecedented stability under temperature fluctuations, less likelihood of fluttering (telegraphing) or deformation on uneven sub-floors, and increased locking strength between panels. This development towards more rigid floor panels (usually with a polymer core) is represented by the WPC (wood plastic composite, in practice with a density of about 900 kg/m)³Foamed PVC core) and at a later stage by SPC (stone plastic composite, density of about 2000 kg/m)³Solid PVC core). SPC was developed on WPCs because it has better dimensional stability when subjected to temperature fluctuations, thus providing a larger mounting surface area and allowing installation in high temperature and high flow areas. However, a disadvantage inherent to rigid floor SPC is its unsatisfactory acoustic properties. The sound performance is poor compared to the original flexible and soft luxury vinyl tile. In general, it can be said that an increase in the filler or mineral content of the product leads to a higher stiffness and an improved dimensional stability, but this also leads to poorer acoustic properties. Acoustic performance in the floor industry is understood to be the reduction in amplitude of sound waves as they move through the floor (sound transmitted to the room below) and the reduction in amplitude as reflected walking sounds are tested (sound heard in the same room). The transmission sound reduction may be tested as "Delta IIC" or "Delta Lw". Both test methods show a reduction in sound transmission to the room below due to the decorative floor, which is the difference between sound transmission with or without decorative floor installed. To improve (reduce)) The sound transmission can be achieved by installing a spacer between the decorative floor and the subfloor, or by attaching a pre-installed sound absorption mat to the back of the decorative floor in a factory. According to an example, 4mm SPC with a 1mm pre-loaded EVA backing can be expected to achieve a Delta Lw result of 12 dB. WPC products with the same specifications typically reach 20 dB. The lower density of the WPC may improve sound absorption.

In addition, it is inherently less dimensionally stable compared to solid core SPC, since it contains a very low mineral content ratio. Therefore, there is a need for a flooring product that has the advantages of both SPC panels (rigid, flutter free, stable) and WPC panels (lower density and improved acoustic performance).

Disclosure of Invention

It is an object of the invention to provide a panel which at least partly has the advantages of both SPC and WPC panels.

The invention provides for this purpose a panel, in particular a floor panel, wall panel or ceiling panel, comprising at least one core layer comprising a composite material comprising at least 20% by weight of a mineral material and preferably a thermoplastic material, wherein the composite material has a top surface and a bottom surface, wherein at least a part of the bottom surface of the core layer is provided with at least one cavity extending towards the top surface.

In a possible embodiment, the composite material comprises (a mixture of) a mineral material and a thermoplastic material. The panels according to the invention are in particular configured for constructing floor coverings, wall coverings or ceiling coverings. The combination of a panel with a composite core comprising a mixture of a mineral material and preferably a thermoplastic material, wherein the composite material comprises at least 20% by weight of the mineral material and at least a part of the bottom surface of the core is provided with at least one cavity extending towards the top surface of the core, allows for improved acoustic performance of the panel relative to a substantially solid panel without compromising the rigidity of the panel. As the core layer of the panel comprises a composite material comprising mineral material and the weight percentage of mineral material is at least 20%, a substantially rigid panel may be obtained. Whereas the panel has a core layer which is substantially completely made of thermoplastic material, the presence of a core layer comprising at least 20% by weight of mineral material contributes to increasing the rigidity of the panel. Substantially rigid panels facilitate relatively easy handling and/or installation as compared to flexible panels. In addition, substantially rigid panels are better equipped to bridge minor protrusions and undulations in the sub-floor without transferring them to the surface. This is particularly advantageous for use as a floor panel, but if the panel is used as a wall panel or a ceiling panel, the rigidity of the panel may also be beneficial. However, as mentioned above, rigid panels often have unsatisfactory acoustic performance. This drawback may be overcome by providing at least one cavity on at least a portion of the bottom surface of the core layer extending towards the top surface. The presence of at least one cavity in the bottom surface of the core layer extending towards the top surface of the core layer results in at least one local reduction of material in the core layer. This may affect the absorption, transmission, reflection, refraction and/or diffraction of the sound waves interacting with the panel. It has been found experimentally that the combination of a composite core provided with at least one cavity according to the invention has a positive effect on the acoustic properties of the panel, wherein a sound damping effect is obtained. This is advantageous as it may eliminate the need to use an additional sound damping layer below the panel. A further benefit of the combination of the composite material according to the invention with the at least one cavity is that the rigidity of the composite material may prevent undesired vibrations of the panel during use. This is also advantageous for the overall performance of the panel during use.

At least a portion of the bottom surface of the core panel is typically substantially flat. In particular, the bottom surface typically defines a substantially flat surface. When referring to a cavity, the terms groove, slot, recess, opening, channel and/or depression may also be used. The cavity is typically a cut-away portion of the panel. Such cavities can either be formed during the production of the panel or can be subsequently carved or cut out. The one or more cavities may be local recesses formed in the bottom surface of the panel, e.g. during production, e.g. during extrusion, substantially immediately after extrusion, during hot pressing, or before curing of the composite material forming the core of the panel. The panels are typically waterproof panels. Due to the good acoustic properties of the panels, the panels may also be referred to as sound-insulating panels.

The panel according to the invention may for example be a substantially longitudinal panel. This is particularly advantageous in case the panel is used as a floor panel. However, it is also conceivable that the panels are substantially rectangular, rhombic or polygonal.

The at least one cavity may be present in a predetermined pattern. The at least one cavity may for example extend from a first distal end of the panel to a second distal end of the panel. In such embodiments, the first distal end is generally opposite the second distal end. It is also conceivable that the at least one cavity is located at a predetermined distance from an edge of the panel. For example, it is conceivable that the at least one cavity does not extend through the (outer) edge of the panel. Thus, the at least one cavity may be substantially centrally located. This was found to be beneficial for the sound absorbing properties of the panel. Such an embodiment may additionally ensure that the stability of the panel is not negatively affected by the cavity or cavities (if applied), as the bottommost surface so formed provides the pull-back strength. A non-limiting example of the predetermined pattern is, for example, a zigzag pattern.

In a preferred embodiment of the panel, at least a part of the bottom surface of the core layer is provided with a plurality of cavities. The plurality of cavities may further contribute to enhancing the acoustic performance of the panel. The cavities may for example be arranged such that a (predetermined) pattern of the cavities affects the acoustic properties, in particular the sound damping properties, of the panel. For such embodiments, typically at least one cavity extends in at least two directions within the same (horizontal plane). Considering that the cavity extends in the y-direction from the bottom surface towards the top surface of the core, these two directions may for example be the x-direction and the z-direction. The at least one cavity may extend in at least two directions, e.g. in a plane defined by the bottom surface of the core layer. Possibly, in case the panel is substantially longitudinal, the at least one cavity may extend in a direction other than the longitudinal direction of the panel. For example, it is conceivable that the cavity extends in a combination of a longitudinal direction and a transverse direction. It is also conceivable that at least one or all cavities are located substantially in the centre of the panel and/or do not extend through the (outer) edge of the panel. It is further conceivable that the cavities are positioned at a predetermined distance from each other. The cavities may also form a network of interconnected cavities. This embodiment may be particularly beneficial because sound waves may travel through such interconnected cavities where sound propagates. The sound waves may lose their energy due to friction between the air particles and the cavity wall through which the sound waves pass. At least one outer edge, preferably all outer edges of the panel may be free of cavities. Thus, it is conceivable that the cavity or cavities do not extend through the outer edge of the panel. For example, it is conceivable that there is no cavity at least 1cm from each outer edge of the panel.

The panels according to the invention may comprise at least one pair of opposite (side) edges comprising complementary coupling parts configured for mutual coupling of adjacent panels. The coupling parts of the panels may for example be interlocking coupling parts, which are preferably configured for providing horizontal and vertical locking. Interlocking coupling portions are coupling portions that require elastic deformation, a click fit, or movement in multiple directions to couple or decouple the portions to or from each other. Any suitable interlocking coupling known in the art may be employed. One non-limiting example is an embodiment in which: wherein a first edge of the first pair of opposing edges comprises a first coupling portion, and wherein a second edge of the first pair of opposing edges comprises a complementary second coupling portion that allows a plurality of panels to be coupled to one another; wherein the first coupling part comprises a lateral tongue extending in a direction substantially parallel to a plane defined by the panels, and wherein the second coupling part comprises a groove configured for receiving at least a part of the lateral tongue of another panel, the groove being defined by an upper lip and a lower lip.

It is conceivable that the panel comprises at least one backing layer, which is preferably attached to the bottom surface of the core layer. The backing layer may provide a protective function for the core layer and thus for the panel. The backing layer may, for example, comprise an adhesive layer. This can then be achieved according to the inventionAdhesive mounting of the panels. It is also conceivable that the backing layer is a balancing layer, preferably configured for stabilizing and/or protecting the panel. The balancing layer may for example prevent the panel from cupping, warping and/or bending. The balancing layer may also be referred to as a stabilizing layer. It is also conceivable that at least one balancing layer is attached to the top surface of the core layer. Possibly, the panel comprises a first balancing layer attached to the top surface of the core layer and a second balancing layer attached to the bottom surface of the core layer. The balancing layer may comprise lignocellulose and a cured resin. The backing layer may be substantially free of cavities. In such an embodiment, the bottom surface of the core layer is provided with at least one cavity, and the backing layer substantially completely covers said bottom surface of said core layer. The backing layer may thereby substantially seal the one or more cavities. However, it is also conceivable that at least one cavity extends from the backing layer into the core layer. Thus, the shape of the at least one cavity of the backing layer may follow or be substantially identical to the shape of the at least one cavity of the bottom surface of the core layer. Either way, the presence of the backing layer may further contribute to the acoustic performance of the panel, as the backing layer may have sound dampening properties and/or facilitate the installation of the panel. In addition, the backing layer may form a moisture barrier. The backing layer is typically made of a polymeric material such as, but not limited to, polyurethane. It is also conceivable that the panel comprises a combination of any of the above examples of possible backing layers. Furthermore, the backing layer may also be an acoustic layer. Such an acoustic backing layer may further contribute to the good acoustic properties of the panel. Such backing layers may also be referred to as acoustic layers. The backing layer may consist of a foam layer of Ethylene Vinyl Acetate (EVA), radiation cross-linked polyethylene (IXPE), expanded polypropylene (XPP) and/or expanded polystyrene (XPS), preferably a low density foam layer thereof. However, it is also conceivable that the backing layer comprises non-woven fibers (e.g. natural fibers such as hemp or cork) and/or recycled/recyclable materials, such as PET. If a backing layer is used, the density is preferably 65kg/m³To 300kg/m³And most preferably 80kg/m³To 150kg/m³In the meantime.

Advantageously, the depth of the at least one cavity is at least 20% of the total thickness of the panel. Regarding the depth of the cavity, the distance measurement in the same spatial direction as the thickness of the panel is considered. In general, in the assembled state of the panels forming a floor covering, both the thickness of the panels and the depth of the cavity can be measured in the vertical direction. It is also possible that the depth of the at least one cavity is at least 30% of the total thickness of the panel. Preferably, the depth of the cavity is no more than 55% of the total thickness of the panel. The latter case prevents the panel from buckling when a load is applied over the panel.

Due to the combination of stiffness and sound absorption, relatively thin panels can be applied. Preferably, the thickness of the panel is less than 3.5cm, more preferably less than 2.75 cm. For example, the thickness of the panel may be between 0.5 and 3cm, preferably between 0.7 and 2.5 cm. Such thickness is significantly less than the thickness of conventional acoustical (wall, floor or ceiling) panels.

In another preferred embodiment, the planar surface area of the bottom surface of the core layer is at least 30% less than the planar surface area of the top surface of the core layer. It was found experimentally that this difference further contributes to the acoustic properties of the panel, while not affecting the stiffness and/or stability of the panel. The top surface of the core layer is typically substantially flat and free of cavities.

The at least one cavity may have a substantially curvilinear geometric cross-section. This may be a cross section of the panel as viewed from a direction perpendicular relative to a plane defined by the bottom surface of the core layer. This may further contribute to the desired absorption, transmission, reflection, refraction and/or diffraction of the sound waves interacting with the panel. It is also possible that the at least one cavity has a substantially curvilinear geometry in a plane defined by the bottom surface. Such a shape may also contribute to sound distribution within the material. It is further conceivable that the part of the core layer surrounding the cavity has a structured surface. For example, the surface of the core layer surrounding the cavity may be at least partially structured. This may also be a contoured or rough surface. Thus, the core layer may have a contoured surface in part, preferably near or at the region defining the cavity. The cavity may be, for example, a substantially elongated cavity. It is further contemplated that at least a portion of at least one lumen is substantially cylindrical, pyramidal, and/or conical. At least a part of the cavity may for example be formed by a substantially semi-cylindrical body, in particular in the plane of the bottom surface. The depth of the at least one cavity may vary over the length and/or width of the cavity. In particular, the shape of the cavities should be chosen such that they enhance the dissipation of impacts and/or the dissipation of airborne sound. Preferably, the geometry of at least one cavity, preferably all cavities, in the bottom surface of the core layer does not cause a difference in longitudinal or lateral flexibility. Thus, the geometry of the cavity or cavities is chosen such that they do not negatively affect the rigidity of the panel.

In another preferred embodiment, the at least one cavity may be at least partially filled with a filler material, such as a sound absorbing material and/or a sound insulating material. This may further contribute to the sound absorption properties of the panel and thus to its acoustic properties. The sound-absorbing material may for example be a natural material, such as bamboo, cocoa fibres and/or cork. Other non-limiting examples of sound absorbing materials that may be used in the present invention are mineral wool, fiberglass, and/or polystyrene foam. In another possible embodiment, the at least one cavity may be substantially completely filled with sound absorbing material.

It is also conceivable that at least one core layer consists of a composite material comprising at least 40% by weight, preferably at least 50% by weight, more preferably at least 60% by weight of mineral material. The core layer may also comprise at least 80% by weight of mineral material. Higher mineral content generally results in a more rigid panel. Furthermore, due to the relatively large amount of mineral material and the relatively low amount of thermoplastic material in the composite core layer, a significantly improved heat resistance can be obtained, in particular with respect to conventional floor panels having a core based mainly on PVC. Thus, the panel according to the invention no longer suffers from undesired shrinkage and expansion due to seasonal and/or local temperature variations.

It is conceivable that at least one core layer comprises at least one mineral material selected from the group consisting of: magnesium oxide, calcium carbonate, chalk, clay, calcium silicate and/or talc. These materials have been shown to impart sufficient rigidity to the composite material. As another non-limiting example, limestone (e.g., calcium carbonate and magnesium carbonate) may be used as the mineral material in the core layer. The mineral material may be present in the form of a particulate mineral filler.

Typically, the core layer of the panel according to the invention consists of a composite material comprising a mixture of mineral material and thermoplastic material. Non-limiting examples of thermoplastic materials are polyvinyl chloride (PVC), Polyethylene (PE), Polyurethane (PU), Acrylonitrile Butadiene Styrene (ABS) and/or polypropylene (PP). The thermoplastic material may also be a vinyl-containing thermoplastic material. The core layer may also comprise mixtures of the aforementioned materials. Typically, the ratio of the weight percentages of mineral material to thermoplastic material is at least 1. Preferably, the composite material comprises at least 15% by weight of thermoplastic material. This lower limit was found to be sufficient to ensure sufficient stability and strength of the core layer. The composite material preferably comprises up to 40% by weight of thermoplastic material. This maximum value is preferable in order to increase the rigidity of the core layer and to significantly improve the heat resistance of the core layer.

The panel, in particular the core layer, may further comprise at least one binder. Preferably, the ratio of the weight percentages of mineral material to the binder is at least 1.

The core layer may further comprise at least one additive selected from the group consisting of: pigments, impact modifiers, lubricants, stabilizers, waxes, and/or processing aids. Various pigments (e.g., inks) impart color to the composite layer. Pigments, if used, are typically present in the composite layer in an amount of 0-5% by weight. As impact modifier, preferably MBS (methacrylate-butadiene-styrene), CPVC (chlorinated PVC), ABS (acrylonitrile-butadiene-styrene) or TPE (thermoplastic elastomer) is used, which is more preferably present in the composite core layer in an amount of 0-5% by weight. Additionally, at least one lubricant may be present, and more preferably an internal lubricant and an external lubricant. The optional stabilizer may be selected to be effective for the particular polymer used, and may be, for example, a calcium zinc stabilizer. Preferably, the total amount of additives present in the composite core layer is limited to 1-15% by weight, more preferably 5-15% by weight, most preferably 8-12% by weight. In a possible embodiment, the core layer is substantially free of natural organic fibers, in particular substantially free of wood (e.g., wood fibers, including wood chips and bamboo chips).

The panels according to the invention may be substantially rectangular, but may also be substantially diamond-shaped or substantially polygonal. In a preferred embodiment, the flexibility of the panel in the longitudinal direction is substantially equal to the flexibility of the panel in the transverse direction. For example, in the case of substantially square or square-like panels, it is also conceivable that the flexibility of the panel in a first direction is substantially equal to the flexibility in a second direction, wherein the first direction and the second direction are defined in one and the same plane, wherein a directional component of the first direction is substantially perpendicular to a directional component of the second direction. Substantially equal means that the average measured deviation between the longitudinal and transverse directions is within 10%, preferably within 5%. A benefit of such an embodiment is that a relatively rigid and stable panel may be obtained. The cavity or cavities are preferably positioned such that the flexibility of the panel is not significantly affected, in particular in at least one direction and possibly in a single direction. For example, it is conceivable that one or more cavities are positioned such that they do not affect flexibility in a first direction, such as, but not limited to, a longitudinal direction.

The modulus of rigidity of the panel is preferably at least 2500 MPa. In another preferred embodiment the modulus of rigidity of the panel in the longitudinal direction is at least 2500MPa and/or wherein the modulus of rigidity of the panel in the transverse direction is at least 2500 MPa. Stiffness is typically measured according to the NEN-EN 310 standard.

It is conceivable that the core layer is an extruded layer formed by an extrusion process. An advantage of forming the core layer by an extrusion process is that the panel can be manufactured in a relatively inexpensive manner. Furthermore, it was found that the extruded core layer is advantageous in terms of the stiffness obtained and is capable of forming a melt bond with the top layer. Here, the extrusion process and the melting process may be simultaneously performed during the manufacturing of the panel. It is particularly advantageous if at least one cavity is formed in the extrusion process. In this way, it is possible to prevent material from being removed from the core after the panel is manufactured. Thus, the panel can be manufactured in a more efficient manner. Furthermore, the formation of residual material is prevented. It is also conceivable that the at least one cavity is formed substantially immediately after the extrusion process. In this context, it is meant that at least one cavity is formed before the core is cured.

In another possible embodiment, it is conceivable that the core layer is formed by hot pressing. For such a technique, the at least one cavity may be formed during the manufacturing process and/or provided after the manufacturing of the panel. The hot pressing may have a positive effect on the rigidity of the panel. It is also conceivable that the core layer is formed by a curing process. With this technique it is also possible to form at least one cavity during the manufacturing process and/or to provide at least one cavity after the manufacturing of the panel.

The panel may further comprise at least one reinforcing layer. Non-limiting examples of such reinforcement layers are glass fibers, polypropylene, jute, cotton and/or polyethylene terephthalate. It is particularly advantageous if the reinforcement layer is at least partially impregnated with a thermosetting resin. Such thermosetting resins may be selected from: melamine formaldehyde resin, phenol formaldehyde resin and/or urea formaldehyde. Typically, if a reinforcement layer is applied, the reinforcement layer is present near the top surface and/or near the bottom surface of the panel. In particular, the reinforcement layer is attached to the core layer.

The panel according to the invention may further comprise at least one top layer, preferably a decorative top layer. Such a decorative top layer may for example be a High Pressure Laminate (HPL), a plurality of impregnated layers comprising lignocellulose, a wood veneer, a thermoplastic layer comprising at least a decorative layer and an optional protective top layer, a stone veneer, etc. and/or a combination of said decorative layers. The decorative top layer may also comprise at least one cellulose-based layer, preferably paper or kraft paper, and a cured resin. The layer of cellulose-based material may also be a veneer layer adhered to the top surface of the core layer. The veneer layer is preferably selected from wood veneer, cork veneer, bamboo veneer, and the like. Other decorative topcoats contemplated by the present invention include ceramic or porcelain tiles, real stone sheets, rubber sheets, decorative plastic or vinyl, linoleum and decorative thermoplastic films or foils which may be laminated with an abrasion resistant layer and an optional coating. Examples of thermoplastics may be PP, PET, PVC, etc. An optional primer may also be provided on the upwardly facing surface of the core and the desired visual effect printed in a direct printing process. The decorative layer may be further finished with a thermosetting varnish or lacquer, such as polyurethane, PUR or melamine based resin. It is also conceivable that the panel comprises a top layer consisting of ceramic tiles. Such tiles may be attached to the top surface of the core layer, for example, by an adhesive such as, but not limited to, polyurethane. It is also conceivable that the top layer is made of ceramic and/or stone. The invention therefore also relates to a panel, in particular a floor panel, a wall panel or a ceiling panel, comprising at least one core layer comprising a composite material, preferably comprising at least 20% by weight of a mineral material; the core layer has a top surface and a bottom surface, wherein at least a part of the bottom surface of the core layer is provided with at least one cavity extending towards the top surface, and wherein the panel comprises at least one top layer attached to the top surface of the core layer. The top layer comprises stone and/or ceramic material. Preferably, the top layer is stone and/or ceramic tile.

The invention also relates to a method for manufacturing a panel, in particular a floor panel, a wall panel or a ceiling panel, preferably according to the invention, comprising the steps of:

providing a composite material, preferably a substantially liquid composite material, comprising at least 20% by weight of a mineral material;

forming a core layer of the composite material, wherein the core layer has a top surface and a bottom surface;

providing at least one cavity in at least a portion of the bottom surface of the core layer extending towards the top surface; and

the core layer is hardened and/or cured.

The formation of the core layer may be accomplished, for example, by extrusion. The method may further comprise the steps of: at least one backing layer is provided and attached to the bottom surface of the core layer and/or at least one top layer is provided and attached to the top surface of the core layer. The method may further comprise the step of machining at least two edges of the panel, wherein said edges are provided with complementary coupling portions.

Drawings

The invention will now be elucidated in more detail with reference to the following non-limiting drawings. In the drawings:

fig. 1a-1d are bottom views of possible embodiments of panels according to the invention, respectively.

Fig. 2a-2e are each a sectional view of a possible embodiment of a panel according to the invention.

Detailed Description

Fig. 1a-1d show schematic views of possible embodiments of panels 100 according to the invention. These figures show a bottom view of the panel 100. Each

panel

100a, 100b, 100c, 100d may be, for example, a floor panel 100, a wall panel 100, or a ceiling panel 100. Each panel comprises a core layer 101, the core layer 101 preferably comprising a composite material comprising a mixture of a mineral material and a thermoplastic material. Each core layer 101 has a top surface not shown in the drawing and a bottom surface shown in the drawing. A portion of the bottom surface of the core 101 of each

panel

100a, 100b, 100c, 100d is provided with at least one cavity 102 extending towards the top surface of the core 101. In the shown embodiment, the

panels

100a, 100b, 100c, 100d are not provided with (interlocking) coupling means. However, it is conceivable to apply the coupling device.

Fig. 1a shows a panel 100a comprising a plurality of substantially parallel cavities 102. Each cavity 102 is positioned a predetermined distance from the peripheral edge of the panel 100 a. It can also be seen that each cavity 102 extends in the longitudinal direction of the panel 100 a. Fig. 1b shows a panel 100b, wherein the cavities 102 form a network of interconnected cavities 102. It has been found through experimentation that such an embodiment may enhance the sound attenuation effect of the panel 100 b. Fig. 1c shows a panel 100c having a plurality of individual cavities 102 extending substantially in the longitudinal direction of the panel 100 c. The cavity 102 widens locally. The at least locally widened region can be filled, for example, with sound-absorbing material. Fig. 1d shows a panel 100d having a series of generally V-shaped cavities 102. The cavities 102 are positioned a predetermined distance from each other and do not interfere with adjacent cavities 102.

Fig. 2a-2e show other possible embodiments of panels 200 according to the invention. The figures show side views of cross sections of

panels

200a, 200b, 200c, 200d, 200e, wherein the

panels

200a, 200b, 200c, 200d, 200e may be floor panels 200, wall panels 200 or ceiling panels 200. Figure 2a shows that the panel 200 may optionally be provided with interconnected coupling parts 203a, 203 b. The interconnected coupling portions 203a, 203b may be applied to any embodiment encompassed by the present invention. Each panel 200 comprises a core layer 201, the core layer 201 preferably comprising a composite material comprising a mixture of a mineral material and a thermoplastic material. Each core layer 201 has a top surface 204 and a bottom surface 205.

Fig. 2a shows a panel 200a comprising a plurality of cavities 202, the cavities 202 being spaced apart from each other by a predetermined distance. The panel 200a further includes a top layer 206. In the embodiment shown, the top layer 206 is a ceramic panel 206 attached to the top surface 204 of the core layer 201. Figure 2b shows a panel 200b in which the depth of the cavities 202 differs between each cavity 202. The cavity 202 is generally trapezoidal in cross-section. Optionally, the panel 200b may include a decorative top layer. Fig. 2c shows an embodiment in which the cavity 202 has a semi-circular cross-section. The cavity 202 is filled with sound absorbing material 207. The panel 200c also includes a backing layer 208 attached to the bottom surface 205 of the core layer 201. Fig. 2d shows that the height or depth h of the cavity 202 is at least 20% of the total thickness t of the panel 200 d. In particular, the depth h of the cavity 202 is about 1/3 of the thickness t of the panel 200 d. Figure 2e shows a side view of a panel 200e, wherein it can be seen that the cavity 202 extends substantially over the entire length of the panel 200e, but that the cavity 202 starts and ends at a predetermined distance from the outer end of the panel 200 e. The panel 200e further comprises a backing layer 208, in particular a balancing layer 208. The cavity 202 is free of filler material, such as sound absorbing material.

It is obvious that the invention is not limited to the embodiments shown and described herein, but that within the scope of the appended claims many variations are possible which are obvious to a person skilled in the art.

The above inventive concept is illustrated by several exemplary embodiments. It is contemplated that various inventive concepts may be applied without the application of the other details of the described examples. It is not necessary to describe in detail all possible combinations of the above-described inventive concepts, since a person skilled in the art will understand that many inventive concepts may be (re) combined to achieve a specific application.

The verb "to comprise" and its conjugations used in this patent disclosure is understood to mean not only "comprising" but also the phrases "comprising", "consisting essentially of … …", "formed of … …" and its conjugations. When referring to a reinforcing layer, it may also refer to a reinforcing element and vice versa.

Claims

1. A panel, in particular a floor panel, a wall panel or a ceiling panel, the panel comprising:

at least one core layer comprising a composite material comprising at least 20% by weight of a mineral material, the core layer having a top surface and a bottom surface,

wherein at least a portion of the bottom surface of the core layer is provided with at least one cavity extending towards the top surface.

2. Panel according to claim 1, wherein at least a part of the bottom surface of the core layer is provided with a plurality of cavities.

3. Panel according to claim 1 or 2, wherein the panel comprises at least one pair of opposite edges comprising complementary coupling parts configured for mutual coupling of adjacent panels.

4. The panel according to any one of the preceding claims, comprising at least one backing layer attached to the bottom surface of the core layer.

5. The panel according to claim 4, wherein the backing layer comprises an adhesive layer.

6. Panel according to claim 4 or 5, wherein the backing layer is a balancing layer.

7. A panel as set forth in any one of claims 4-6, wherein said backing layer is an acoustic layer.

8. A panel as set forth in any one of claims 4-7, wherein said backing layer is substantially free of cavities.

9. A panel as set forth in any one of claims 4-7, wherein at least one cavity extends from said core into said backing layer.

10. Panel according to any one of the preceding claims, wherein the depth of at least one cavity is at least 20% of the total thickness of the panel.

11. Panel according to one of the foregoing claims, wherein at least one cavity has a substantially curvilinear geometry, in particular in a plane defined by the bottom surface of the core.

12. Panel according to any one of the preceding claims, wherein at least a part of at least one cavity is substantially cylindrical, pyramidal and/or conical, in particular perpendicular to a plane defined by the bottom surface of the core.

13. Panel according to one of the foregoing claims, wherein the depth of at least one cavity varies over the width and/or length of the cavity.

14. Panel according to one of the foregoing claims, wherein the depths of at least two cavities are different.

15. Panel according to any one of the preceding claims, wherein at least one cavity is filled with sound absorbing material.

16. Panel according to any one of the preceding claims, wherein the core layer comprises at least 40% by weight, preferably at least 50% by weight, more preferably at least 60% by weight of mineral material.

17. Panel according to any one of the preceding claims, wherein the core layer comprises at least one mineral material selected from: magnesium oxide, calcium carbonate, chalk, clay, calcium silicate and/or talc.

18. Panel according to any one of the preceding claims, comprising at least one binder and preferably the ratio of the weight percentages of mineral material to the binder is at least 1.

19. Panel according to any one of the preceding claims, wherein the core layer further comprises at least one additive selected from the group consisting of: pigments, impact modifiers, lubricants, stabilizers, waxes, and/or processing aids.

20. Panel according to one of the foregoing claims, wherein the flexibility of the panel in the longitudinal direction is substantially equal to the flexibility of the panel in the transverse direction.

21. Panel according to any one of the preceding claims, wherein the modulus of rigidity of the panel is at least 2500 MPa.

22. Panel according to claim 21, wherein the modulus of rigidity of the panel in the longitudinal direction is at least 2500MPa and/or wherein the modulus of rigidity of the panel in the transverse direction is at least 2500 MPa.

23. Panel according to any one of the preceding claims, wherein the core layer is an extruded layer formed by an extrusion process, or a calendered layer formed by a calendering process, or a cured layer formed by a curing process.

24. Panel according to any one of the preceding claims, wherein at least one cavity is formed during the extrusion process, or substantially immediately after the extrusion process, or by a hot pressing process or by a curing process.

25. Panel according to one of the foregoing claims, comprising at least one reinforcing layer.

26. Panel according to one of the foregoing claims, comprising at least one top layer, preferably a decorative top layer.

27. Panel according to one of the foregoing claims, wherein at least one outer edge, preferably all outer edges of the panel are free of cavities.

28. A method for manufacturing a panel, in particular a floor panel, a wall panel or a ceiling panel, preferably a panel according to any one of claims 1 to 27, the method comprising the steps of:

providing at least one cavity in at least a portion of the bottom surface of the core layer extending toward the top surface; and

hardening and/or curing the core layer.