WO2021152154A1

WO2021152154A1 - Floor panel and method of manufacturing of a floor panel

Info

Publication number: WO2021152154A1
Application number: PCT/EP2021/052218
Authority: WO
Inventors: Thomas Luc Martine BAERT; Tom VAN POYER; Sven Boon
Original assignee: Champion Link International Corporation
Priority date: 2020-01-31
Filing date: 2021-01-29
Publication date: 2021-08-05
Also published as: CN113202252A; EP4096913A1; NL2024807B1

Abstract

The invention relates to a panel suitable for constructing a floor or wall covering. The panel according to the present invention comprises a core comprising a mineral material, and comprising at least one pair of opposite side edges which are provided with interconnecting coupling means for interconnecting adjacent panels, the panel further comprises an additive in order to improve the flexibility and/or tensile strength of the panel.

Description

Floor panel and method of manufacturing of a floor panel

The invention relates to a panel suitable for constructing a floor or wall covering. The invention further relates to a method of manufacturing a panel suitable for constructing a floor or wall covering.

The flooring industry uses mainly traditional materials for manufacturing (laminated) floor tiles. Examples of commonly used materials are high density fiberboard (HDF) which can be merged together by a formaldehyde or phenol-based resin, heterogeneous or homogeneous polyvinyl chloride (PVC) which may possibly comprise any plasticizers, pieces of solid hardwood, or layers of veneers glued together, and fired and glazed clay such as ceramic and porcelain tiles. The purpose of use of these materials depends mainly on their material properties such as impact resistance, rigidity, acoustic performance and/or appearance.

An interest in the use of alternative materials has occurred relatively recently, mostly due to a demand from the market for greener or more sustainable products. A prime example thereof is the use of mineral materials, since mineral materials are usually abundant resources, generally benefit a relatively high compressive strength and dimensional stability and a resistance to heat and fire. As such, they have certain clear advantages over plastic and HDF-based flooring panels.

Mineral based floorings generally utilize two major materials: calcium or magnesium. These materials are processed and form the basis of hydraulic cement and non-hydraulic cement respectively. The cement is generally cured into the shape of a board and used as a core or carrier plate and laminated together with a decorative layer. Calcium-based or hydraulic cement panels feature a core board made of a cement based on calcium carbonate or silicate. The high alkalinity of these hydraulic calcium-based cements does not allow for the addition of reinforcing materials such as fiberglass. This has greatly restricted their popularity in the flooring industry, as they are too fragile to withstand the stresses that high foot traffic places on their locking mechanism. Magnesium-based panels have a core board comprising a non-hydraulic cement based on magnesium oxychloride or oxysulfate. This cement features excellent strength and fire-retardant properties so it is widely employed in the building materials industry to produce a fire-retardant alternative to gypsum or particle board wall panels. Recent improvements in magnesium cement technology, such as a higher density, and specific constructions of fiber meshes incorporated in the boards, allow for their use in flooring panels. Still, generally these magnesium-based boards are light-weight, around 1300 to 1500kg/m3, and brittle. Like calcium-based hydraulic cements, they lack the flexibility required to be installed as a floor, even more so to be equipped with a locking mechanism on the side of the boards for floating installation. This would require a flexibility that is commonly accepted as being inherently impossible for this type of material.

Hence, it is a goal of the invention to provide a mineral-based panel having an improved flexibility, to allow for use as a floor; and allow for the milling of a locking mechanism at the side edges of the floor panel.

The invention provides thereto a panel suitable for constructing a floor or wall covering, comprising a core comprising a mineral material, and comprising at least one pair of opposite side edges which are provided with interconnecting coupling means for interconnecting adjacent panels, wherein the core further comprises at least one dendritic additive.

The addition of this at least one dendritic additive to the mineral based core may improve the flexibility and/or tensile strength of the core. The yield strength of the core, and thus the panel’s carrying strength may be improved due to the use of a dendritic additive. This improves the ability of the mineral material for being used in flooring purposes. Due to this improved flexibility and/or tensile strength it is also enabled that interconnecting coupling means can be applied in practice for a (floor) panel having a mineral based core. The improved flexibility and/or tensile strength prevents breakage of the protruding parts of the coupling means provided at the edges of the panel when tension is exerted onto said protruding parts. The improved flexibility and/or tensile strength can be explained by the dendritic additive inducing dendritic crystal growth within the mineral based core; while at the same time breaking up and centering the crystal structure. This may cause that in at least part of the core a web structure of crystals is obtained. At least one dendritic additive can for example be present in the form of three dimensionally expanded flexible crystallization matrix. Hence, the dendritic additive serves as frame for crystallization within the mineral material. The dendritic crystal structure in the mineral based changes the overall material properties of the final product, i.e. the (floor) panel as such. However, the addition of at least one dendritic additive does not negatively affect the dimensional stability and heat resistance of the panel. The dendritic additive is typically present within the core.

The panel according to the present invention is in particular suitable for use in flooring, wall or ceiling coverings featuring a locking mechanism. The panel comprising at least one pair of opposite side edges which are provided with interconnecting coupling means for interconnecting adjacent panels. Preferably the panel according to the invention comprises two pairs of opposite side edges which are provided with interconnecting coupling means. As such a 'floating' covering can be assembled by interconnecting the individual panels with each other at all four sides, without the need for adhesives. It is further conceivable that the interconnecting coupling means comprise a tongue and a groove wherein the tongue is provided on one side edge of one pair of opposite side edges, and the groove is provided on the other side edge of the same pair of opposite side edges. Such a design of coupling means is well-known in the art and has proven highly suitable for panels for floor coverings such as a floating floor. In a further embodiment it is possible that the interconnecting coupling means have an interlocking feature which avoids free movement (play) of interconnected panels. Such an interlocking feature may be a projection and a respective recess provided on the respective opposite side edges by which neighboring panels interlock with each other.

The panel according to the present invention may comprise at least one top layer affixed to said core. The top layer may for example be a decorative layer. It is also conceivable that the top layer comprises a decorative layer and a wear layer covering said decorative layer. The decorative layer may be composed of a film provided and/or printed with a motif. The decorative layer may be a paper layer and/or a polymer layer, such as a PVC layer. The wear layer is commonly substantially transparent. The wear layer may consist of one or more transparent lacquer layers. Typically, the thickness of the layer(s) in the panel is in the range of 0.2 to 2.0 mm. The panel according to the present invention is typically a laminated panel. A decorative top layer, if applied, may for example comprise at least one ply of cellulose-based layer and a cured resin, wherein the cellulose-based layer is preferably paper or kraft paper. Said ply of cellulose-based material may also be a veneer layer adhered to a top surface of the core layer. The veneer layer is preferably selected from the group consisting of wood veneer, cork veneer, bamboo veneer, and the like. Other decorative top layers that could possibly be applied for the present invention include a ceramic tile, a porcelain tile, a real stone veneer, a rubber veneer, a decorative plastic or vinyl, linoleum, and decorative thermoplastic film or foil. The top layer may possibly be further provided with a wear layer and optionally a coating. Examples of thermoplastics which could be used in such top layer are PP, PET, PVC and the like. It is also possible to provide on the top facing surface of the core an optional primer and print the desired visual effect in a direct printing process. The decorative top layer can receive a further finishing with a thermosetting varnish or lacquer such as polyurethane, PUR, or a melamine based resin.

It is also conceivable that the panel comprises at least one backing layer affixed to the core. It is also conceivable that the panel comprises (at its back surface) at least one balancing layer, generally composed of at least one layer comprising lignocellulose and a cured resin. The panel may also comprise at least one acoustic layer, usually composed of a low density foamed layer of ethylene-vinyl acetate (EVA), irradiation-crosslinked polyethylene (IXPE), expanded polypropylene (XPP), expanded polystyrene (XPS), but also nonwoven fibers such as made from natural fibers like hemp or cork, or recycled/recyclable material such as PET or rubber. The density of this acoustic layer preferably has a density between 65 kg/m3 and 300 kg/m3, most preferably between 80 kg/m3 and 150 kgm3.

The dendritic additive can for example be a dendritic polymer. Such dendritic polymer can possibly have a monodisperse framework or a polydisperse framework. Non-limiting examples of possible dendritic polymers are dendrimers, dendrons, star polymer, hyperbranched polymer, dendrigrafts or linear-dendritic polymers. The dendritic polymer is preferably non-linear. The dendritic additive can for example be a dendritic polyurethane. Further non-limiting examples of dendritic polymers are polylactic acid, polypropylene and/or polysiloxane. Per definition, one- dimensional and/or polymers with a straight chain do not fall within the scope of a dendritic additive according to the present invention.

Preferably, the core comprises in the range of 0.1 to 10 wt% dendritic additive, preferably in the range of 0.5 to 5 wt%, and more preferably in the range of 1 to 2 wt%. It is for example possible that the amount of dendritic additive is in the range of 0.7 to 2wt% of the total weight of mineral material. It is experimentally shown that said ranges provide the most promising results with respect to the desired material properties for the goal of the invention.

It is conceivable that the core is a multilayer core. Hence, the core may comprise at least one upper core layer and at least one lower core layer, wherein at least one core layer comprises at least one dendritic additive. Preferably all core layers comprise at least one dendritic additive. It is possible that different core layers have a different density. It is conceivable that the core comprises at least one reinforcing layer. In a possible embodiment, the core comprises multiple core layers wherein two adjacent core layers enclose a reinforcing layer. The presence of at least one reinforcing layer may further enhance the impact resistance of the core, and thus the panel. At least one reinforcing layer may for example be present in the form of a reinforcing mat, a membrane and/or a mesh. At least one reinforcing layer may for example comprise fiber glass, polypropylene, jute, cotton and/or polyethylene terephthalate.

At least part of the dendritic additive may possible be a nanodendritic addititive.

The use of nanodendritic additive may positively affect the crystallization of the mineral material within the core. It is also conceivable that at least part of the dendritic additive has an average particle size in the range of 5 to 250 micrometer, preferably in the range of 50 to 100 micrometer. The surface area of the dendritic additive is for example in the range of 5 m²/g to 50 m²/g.

The invention also relates to the use of a panel according to the present invention. Hence, the invention relates to the use of a panel comprising dendritic particles in core of a mineral based floor panel.

The invention further relates to a method of manufacturing a panel suitable for constructing a floor or wall covering, in particular a panel according to the present invention, wherein the core is made by adding least one dendritic additive to a mineral material.

The mineral material comprising the core may for example be a magnesium oxide or magnesia (MgO). The magnesia can be calcined in order to affect the reactivity of the material. With respect to the present invention, the magnesia is typically obtained via a calcination process which is applied at temperatures of about 600 to 1300 degrees Celsius, preferably between 800 and 1000 degrees Celsius, such that reactive magnesia, which has a relatively high reactivity, is obtained. Reactive magnesia is also known in the field as “caustic-calcined magnesia” or light-burned magnesia. Typically, this is a highly reactive calcined MgO with a relatively small crystallite size. The magnesium cement, which can be used as primary core material, can be produced by mixing this reactive magnesia with an aqueous magnesium salt solution (usually conprising MgS04, MgCI2 and/or MgC03), then mixing this slurry with additives and water. Subsequently, the slurry is cured in order to form a ceramic material. This ceramic cement is poured onto a mold, and allowed to set, typically at either ambient or elevated temperature until it has cured. Non-limiting examples of these cements which can be used are magnesium chloride (MOC), magnesium oxysulfate (MOS) or magnesium carbonate. The magnesium chloride cement can be present in the 5-1-8 phase (5Mg(0H)2.MgCI2.8H20) or the 3-1-8 phase (3Mg(0H)2.MgCI2.8H20). Both of these phases form needle- or whisker-like crystals which benefit from useable properties, such as a dense microstructure and high bending strength. Magnesium oxysulfate cement can be present in the 5-1-3 phase (5Mg(0H)2.MgS04.3H20) or the 3-1-8 phase (3Mg(0H)2.MgS04.8H20). The former shows a needle- or whisker- like structure of typically 0.2 to 1.0 micrometer in diameter and a length of 20 to 50 micrometer; whereas the latter shows a flaky crystal structure.

At least one dendritic additive is preferably added to the abovementioned slurry during mixing prior to curing. The dendritic additive can achieve that a three- dimensionally expanded flexible crystallization matrix will be formed that serves as a frame for the crystallization of the magnesia. This three-dimensionally expandable dendritic additive typically consists of a material that features a resemblance to or have dendrites, including linear or non-linear branched polymers, star polymers, dendrimers that can provide an interwoven skeleton to the setting magnesia cement crystals. When the term dendrimer is used, repetitively branched molecules can be meant. Typically not included are any linear, one dimensional and/or straight-chained polymers such as polyethylene, nylon, polyester, PVC, PAN, alkanes or similar.

It is also conceivable that in stead of a magnesium based core any other crystal based cement is used in relation to the present invention.

The method may further comprise a step wherein least one pair of opposite side edges of the panel is provided with interconnecting coupling means for interconnecting adjacent panels. This can be any conventional coupling means, such as aforementioned non-limiting examples.

The invention also relates to a method of manufacturing a panel suitable for constructing a floor or wall covering, according to the present invention, wherein at least one dendritic additive is added to the core.

The invention further relates to a method for producing a panel, in particular a floor or wall panel, preferably according to any embodiment of the present invention, the method comprising the steps of: a) preparing a magnesium oxide composition comprising magnesium salt and water; b) mixing at least one composition comprising at least one dendritic additive to the magnesium oxide composition to form a mixture; c) optionally applying a force of at least 7MPa to the mixture at a temperature in the range of 45 to 55 degrees Celsius for a predetermined period of time such that a core layer comprising an upper core surface and a lower core surface is obtained.

The magnesium oxide composition can also be referred to as magnesium oxide cement composition. The screening step can also be a sieving step. The magnesium oxide composition can for example be a magnesium oxide powder.

The magnesium oxide composition can be a damp composition. The magnesium oxide composition can be an aqueous composition or a slurry. The composition comprising at least dendritic additive preferably comprises up to 90% by weight of dendritic additive. The steps of said method are generally subsequent steps. After the pressure of step c) is released, a core layer, or core board whereof multiple core layers can be formed, is obtained. The method according to the preferred embodiment of the present invention allows to produce a core layer having a density in the range of 1200 kg/m3 to 1600 kg/m3, in particular between 1350 kg/m3 and 1550 kg/m3. The method also enables that a core layer can be obtained having a density which is substantially constant over the entire volume of the core layer. This can at least partially be explained by the pressure applied at step c). A substantially constant density is also beneficial for the overall strength of the panel. It is also possible to provide multiple layers of a magnesium oxide composition with different additive ratios so that a core layer can be obtained having a density which fluctuates over the entire volume of the core layer. Typically, the magnesium oxide composition, e.g. magnesium oxysulfate cement and magnesium chloride cement, is formed by mixing at least one magnesium oxide powder and brine. The magnesium oxide damp composition is in practice a substantially powdery composition, which has a lower water content than a convention magnesium oxide slurry. The magnesium oxide composition is typically slightly wet but not soaked. Hence, the magnesium oxide composition can also be classified as textured composition. Preferably, the magnesium oxide composition is mixed prior to at least one screening step. During at least one screening step, a mesh size between 10 and 35 mm could for example be applied. The screening step can, for example, be achieved by making use of a processor which preferably comprises brushes and/or screens, for example screens having a mesh size between 10 and 35 mm. It is also possible that multiple subsequent screening steps are applied to ensure that the screened magnesium oxide cement damp composition is even.

The method according to the present invention allows to achieve panels having a rather consistent density, which can be at least partially explained by the combination of steps a) to c). These steps also at least partially prevent bubble formation and/or remove gas and/or bubbles present in the composition. Step c) enables the (chemical) reaction of the components of the magnesium oxide composition to finish and/or to cure the magnesium oxide composition. A further benefit of the method according to the present invention is that where conventional magnesium oxide cement based panels are typically produced by a process using excessive water, the panel according to the preferred embodiment of the present invention can produce via a more water efficient method. In practice, this means that substantially less watering process is used, and needed, during the production process and it also enables a significant reduction of the overall production time. Hence, no overload of water is applied during the production process, which is amongst others, beneficial from environmental point of view. Typically, a predetermined amount of water is applied for forming the magnesium oxide damp composition, wherein the amount is determined based upon the water required for the (chemical) reaction with magnesium oxide and optionally any further components and/or curing thereof. For example, the amount of water to be used can be controlled based upon the desired properties of the final product and the desired crystal structure in the core layer. More specifically, the amount of water in weight percentage or molar ratio added to the composition directly influences which crystal structure is formed in the core layer during the pressing phase.

Step c) of the method can, for example, be achieved via at least one pressing and/or compressing step. Step c) enables the removal of excessive liquid from the magnesium oxide cement composition. During step c), the magnesium oxide composition is typically dried and/or cured. The at least one screening step enables that a more even magnesium oxide composition can be obtained. Where it is referred to a mold, a conveyer, container and/or a plate can also be meant. Basically, due to the magnesium oxide damp composition having a relatively functional structure, it is not required that the mold comprises raised edges and/or a rim. Typically, the magnesium oxide damp composition has a relatively low moisture content, wherefore the damp composition does not behave like a liquid. This enables easier handling of the composition during processing thereof. The method may for example involve applying a layer which is at least partially 4 to 7 cm in thickness of the magnesium oxide cement damp composition in or upon the mold. As indicated above, the method can also allow the production of core board whereof multiple core layers are formed.

As indicated above, a core layer comprising magnesium oxide cement and natural fibers, may have a density in the range of 1350 kg/m3 to 1550 kg/m3, resulting in a core layer having a relatively good flexural and structural strength. Preferably, the magnesium oxide composition formed at step a) has a moisture content below 25 wt%, preferably below 10 wt%, more preferably at 7 +/- 2 wt%. It is for example possible that the magnesium oxide composition formed at step a) has a moisture content between 10 and 1 1 2 wt %. It is possible to apply such relatively low moisture content due to the combination and/or fractions of materials used and the process steps applied in the present method. As indicated above, in the prior art it is known to produce magnesium oxide cement based panels via an extensive and time consuming process of drying of a magnesium oxide cement slurry, wherein the slurry contains at least 50 wt% of water, and often even over 60 wt% water. The need to use an overload of water is overcome by the method according to the present invention. The magnesium oxide composition may further comprise magnesium hydroxide, magnesium chloride and/or magnesium oxysulfate. The magnesium oxide composition may further comprise any of the additives and/or fillers as described for the present invention.

It is conceivable that natural fibers are added to the magnesium oxide composition after or during step a). The magnesium oxides composition may for example comprises at least 30 wt% natural fibers. The natural fibers may comprise at least one element chosen from the group of: wood fibers, bamboo fibers, animal fibers, and/or mycelium fibers. The natural fibers may be any of the above described natural fibers and may be present in any of the above described volumes. The average length of the natural fibers may for example be at least 2 mm. The natural fibers may comprise lignocellulose fibers, such as but not limited to wood fibers. Mixing of the magnesium oxide composition may contribute to at least part of the natural fibers being encapsulated by magnesium oxide cement. It is experimentally found that magnesium oxide and natural fibers effectively bond under pressure.

The method is typically performed under ambient conditions. However, it is also conceivable that the method is performed under vacuum or under a predetermined pressure above atmospheric pressure. Step c) is typically performed for a duration of at least 2 hours, preferably at least 4 hours. Step c) is in a further preferred embodiment performed for a duration between 6 hours to 12 hours. Afterwards, the panels can be demolded and/or cured. The method may comprise the step of demolding of the obtained core layer.

The boards or panels typically have an initial strength that is at least 50% of the final strength after said duration intervals, and are the sufficiently strong to be further processed. Hence, the required process time is significantly shorter than the process time which are typically required for the production of a magnesium oxide based panel. Conventional processes for the production of a magnesium oxide based panel typically have a duration of at least seven days, which can be even longer in case a layer of fiberglass is included in the panel.

The method may optionally comprise the step of attaching at least one decorative top layer to an upper core surface of the core layer, preferably by applying heat and/or pressure. This step is made possible due to the technical possibility of avoiding the creation of a density gradient in the panel, in particular in the core layer of the panel, which is a result of the pressure applied at step c) and the consistency of the composition. It is also conceivable that a density gradient is present in the panel. It is possible to provide a core with a consistent density gradient, or a lack of density gradient, that being a core with an even specific gravity across the volume of the core.

The current method enables the production of a panel having a core layer with a density that is substantially constant over the entire volume of the core layer thereby increasing the overall strength thereof which allows the panel to withstand further application of heat and pressure without being damaged. With the core layer being free of any regions and/or zones having an increased density, which is typical of conventional magnesium oxide cement based panels, hot pressing of at least one layer of impregnated paper, or lignocellulose impregnated with a resin, to the upper and lower surfaces of the panel is made possible without causing the panel to warp or bend despite the core layer comprising magnesium oxide cement. Hot pressing of at least one layer of impregnated paper to the upper and lower surfaces of the panel is typically done by applying heat and pressure to the panel, more specifically to the core layer thereof. Optionally, the core layer can be subjected to a sanding process to increase adhesion prior to hot pressing. Preferably, the core layer is subjected to a temperature ranging from 100 - 200 , more preferably 170 -200 °C, most preferably 175 -190 and to pressure ranging from 5-

25Mpa, more preferably 18-22Mpa, most preferably around 20Mpa. The application of heat and pressure to the core layer is conceived to last for at least 10 seconds to about 45 minutes, more preferably at least 30 seconds to about 90 seconds, most preferably at least 50 seconds to about 80 seconds. The method may also comprise the step of profiling and/or edging of at least one side edge of at least one panel, and in particular the core layer of the panel. Such step may for example involve that at least one pair of complementary coupling parts is provided at least two opposite side edges of the panel, preferably wherein the complementary coupling parts are configured such that in a coupled state a pretension is existing. In a preferred embodiment, the complementary coupling parts specifically contain a higher ratio of 5-phase whisker phase to 3-phase flake phase, allowing for a pretension to exist in the coupled state of the coupling parts due to the enhanced strength the 5-phase content provides to the coupling parts. It is possible and desirable therefore that the coupling parts contain a 5-phase to 3- phase magnesium cement of more than 1 , where the rest of the core may have a different ratio.

The method may for comprise a step of attaching at least one decorative top layer to the upper core surface of the core layer and/or attaching at least one balancing layer to the lower core surface of the core layer. Non-limiting examples of possible balancing layers and/or decorative top layers to be used are described above for the panel according to the present invention.

In a further possible embodiment, a layer of magnesium oxide damp composition is during step c) subjected to a force having a pressure between 7 MPa and 20 MPa. It is, for example, also possible that the magnesium oxide damp composition is subjected to a force having a pressure below 18 MPa. The preferred pressure applied is at least partially dependent of the desired thickness and/or density of the final product.

The invention will be further elucidated based upon the following non-limitative clauses.

1 . Panel suitable for constructing a floor or wall covering, comprising: a core comprising a mineral material, and comprising at least one pair of opposite side edges which are provided with interconnecting coupling means for interconnecting adjacent panels, characterized in that the core further comprises at least one dendritic additive. 2. Panel according to clause 1 , comprising at least one top layer affixed to said core.

3. Panel according to any of the previous clauses, wherein the mineral material comprises magnesium oxide, magnesium oxysulfate and/or magnesium oxychloride.

4. Panel according to any of the previous clauses, wherein the dendritic additive is a dendritic polymer.

5. Panel according to clause 4, wherein the dendritic polymer is non-linear.

6. Panel according to any of the previous clauses, wherein the core comprises 0.1 to 10 wt% dendritic additive, preferably 0.5 to 5wt%, more preferably 1 to 2wt%.

7. Panel according to any of the previous claim, wherein the core is a multilayer core.

8. Panel according to clause 7, wherein the core comprises at least one upper core layer and at least one lower core layer, wherein at least one core layer comprises at least one dendritic additive.

9. Panel according to any of the previous clauses, wherein the core comprises at least one reinforcing layer.

10. Panel according to clause 9, wherein the reinforcing layer comprises fiber glass, polypropylene, jute, cotton and/or polyethylene terephthalate.

11 . Panel according to any of the previous clauses, wherein the dendritic additive is a nanodendritic addititive.

12. Panel according any of the previous clauses, wherein at least part of the dendritic additive has an average particle size in the range of 5 to 250 micrometer, preferably in the range of 50 to 100 micrometer. 13. Use of a panel according to any of clauses 1 -12.

14. Method of manufacturing a panel suitable for constructing a floor or wall covering, in particular a panel according to any of clauses 1-12, wherein the core is made by adding least one dendritic additive to a mineral material.

15. Method according to clause 14, wherein at least one pair of opposite side edges of the panel is provided with interconnecting coupling means for interconnecting adjacent panels.

Claims

1 . Panel suitable for constructing a floor or wall covering, comprising: a core comprising a mineral material, and comprising at least one pair of opposite side edges which are provided with interconnecting coupling means for interconnecting adjacent panels, characterized in that the core further comprises at least one dendritic additive within the core.

2. Panel according to claim 1 , comprising at least one top layer affixed to said core.

3. Panel according to any of the previous claims, wherein the mineral material comprises magnesium oxide, magnesium oxysulfate and/or magnesium oxychloride.

4. Panel according to any of the previous claims, wherein the dendritic additive is a dendritic polymer.

5. Panel according to claim 4, wherein the dendritic polymer is non-linear.

6. Panel according to any of the previous claim, wherein the core comprises 0.1 to 10 wt% dendritic additive, preferably 0.5 to 5wt%, more preferably 1 to 2wt%.

8. Panel according to claim 7, wherein the core comprises at least one upper core layer and at least one lower core layer, wherein at least one core layer comprises at least one dendritic additive.

9. Panel according to any of the previous claims, wherein the core comprises at least one reinforcing layer.

10. Panel according to claim 9, wherein the reinforcing layer comprises fiber glass, polypropylene, jute, cotton and/or polyethylene terephthalate.

11. Panel according to any of the previous claims, wherein the dendritic additive is a nano-dendritic additive.

12. Panel according any of the previous claim, wherein at least part of the dendritic additive has an average particle size in the range of 5 to 250 micrometer, preferably in the range of 50 to 100 micrometer.

13. Method of manufacturing a panel suitable for constructing a floor or wall covering, in particular a panel according to any of claims 1-12, wherein the core is made by adding least one dendritic additive to a mineral material.

14. Method according to claim 13, wherein at least one pair of opposite side edges of the panel is provided with interconnecting coupling means for interconnecting adjacent panels.