Sheet material for a decorative panel

Abstract

A sheet comprises a polymer matrix, a first filler material and a second filler material. The first filler material is selected from wood material, plant-based material, mineral fillers, or combinations thereof. The second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3. The first filler material as well as the second filler material are embedded in the polymer matrix. The polymer matrix is selected from a thermoplastic matrix, a thermoset matrix or combinations thereof.

Description

[0001] Sheet material for a decorative panel

[0002] The invention relates to a sheet material for a decorative panel, to decorative panels comprising such sheet material, and to methods for making such sheet material and such decorative panels. The sheet material provides sound dampening properties to the decorative panels when used as floor panels.

[0003] W02021 / 009584A1 discloses a sheet material with at least two layers of material: a first layer of material and a second layer of material. The first layer of material forms more than half of the thickness of the sheet material and is mainly built up from wood particles glued by means of a thermosetting binder and pressed. The second layer of material is present on the surface of the sheet material and is mainly built up from particulate particles glued by means of a second binder and pressed. The second binder is thermoplastic and / or elastomeric.

[0004] WO2024 / 074931A1 discloses a decorative panel comprising a decorative top layer, an intermediate layer and a carrier layer. The intermediate layer is located between the decorative top layer and the carrier layer. The intermediate layer comprises wood particles, low-density particles and a polymer binder. The low-density particles have a density of less than 0.35 g / cm3. The polymer binder binds the wood particles and the low-density particles in the intermediate layer.

[0005] It is an object of the invention to provide improved sheet material for producing floor panels with improved sound properties when being walked upon.

[0006] It is an object of the invention to provide methods for producing such sheet material and decorative panels comprising such sheet material.

[0007] The first aspect of the invention is a sheet. The sheet comprises a polymer matrix, a first filler material and a second filler material. The first filler material is selected from wood material, plant-based material, mineral fillers, or combinations thereof. The second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3. The first filler material as well as the second filler material are embedded in the polymer matrix. The polymer matrix is selected from a thermoplastic matrix, a thermoset matrix or combinations thereof.

[0008] It is a benefit of the invention that a sheet is obtained that can be used in floor covering products - e.g. in decorative floor panels - and that provides the floor covering product with sound dampening properties when being walked upon, while the impact properties of the floor covering product are still good. The favorable combination of properties is obtained thanks to the combination of the first filler material and the second filler material.

[0009] The preferred at least partial use of a thermoplastic matrix is beneficial for synergistically improving the sound dampening properties of the sheet and of floor coverings in which the sheet is incorporated.

[0010] Sheets wherein the polymer matrix is a thermoset matrix or a combination of a thermoplastic matrix and a thermoset matrix are preferred as they provide improved possibility of using the sheet in a lamination process at increased temperature in which the sheet is laminated onto a board, and / or in which a decorative top layer is laminated onto the sheet.

[0011] The thermoset matrix, or the thermoset part of the polymer matrix, will ensure that the sheet has sufficient strength for the lamination process.

[0012] The first filler material preferably is particulate matter.

[0013] The polymer matrix can be a 100% thermoset polymer matrix.

[0014] Preferred wood material for use in the invention has a density higher than 0.5 g / cm3. The first filler material can comprise wood fibers or wood particles (e.g. wood chips), or combinations thereof.

[0015] The wood fibers and / or the wood particles can be coated with a thermoset binder. Such embodiments provide excellent bonding of the wood fibers and / or the wood particles in the polymer matrix. It also ensures that effective bonding is created at contacts between the wood fibers and / or the wood particles on the one hand and the second filler material on the other hand.

[0016] It is a further benefit that the thermoset binder with which the wood fibers and / or wood particles are coated shield the wood fibers and / or wood particles from moisture. As a results a sheet having improved resistance to moisture is obtained.

[0017] Preferred plant-based materials for use in the invention as first filler material in the invention are plant-based particles, such as e.g. flax shives or miscanthus particles. The plant-based particles can be coated with a thermoset binder.

[0018] The plant-based material can be coated with a thermoset binder. Such embodiments provide excellent bonding of the plant-based material in the polymer matrix. It also ensures that effective bonding is created at contacts between the plant-based material and the second filler material.

[0019] Preferred thermoset binders with which the wood fibers, the wood particles or the plantbased material can be coated include aminoplast binders (e.g. urea formaldehyde, melamine formaldehyde, melamine urea formaldehyde), isocyanate binders (e.g. polymeric methylene diphenyl diisocyanate), polyurethane binders, acrylate binders, vinyl-acetate binders, epoxy binders, biobased binders, hyperbranched polyamide binders, or combinations thereof.

[0020] The wood fibers, the wood particles or the plant-based material can be coated with a thermoset binder prior to producing the sheet. This is an elegant way of applying thermoset binder, and ensures that the wood fibers, the wood particles or the plant-based material are well bonded in the polymer matrix. It also ensures that the thermoset binder applied is well distributed.

[0021] Thermoset binder can have been applied in other ways than via coating the first filler material (e.g. the wood fibers, the wood particles, the plant-based material) with thermoset binder. Thermoset binder can have been sprayed during the production process of the sheet. Such spraying can take place even if the first filler material has not been coated with thermoset binder.

[0022] Use of a thermoplastic matrix or use of a polymer matrix being the combination of a thermoplastic matrix and a thermoset matrix has the benefit that the sheet has excellent resistance to moisture.

[0023] A combination of a thermoplastic matrix and a thermoset matrix can be an interconnected network of a thermoplastic and a thermoset matrix. Alternatively, the polymer matrix can be in part thermoset in nature and in part thermoplastic in nature.

[0024] A preferred sheet is characterized in that the first filler comprises or consists of one or more of calcium carbonate, talcum, fly ash, magnesium oxide, grit, or kaolinite. Optionally, the mineral fillers can be coated with a thermoset resin to improve the strength of their embedment in the polymer matrix of the sheet.

[0025] Such inorganic fillers are readily available and cheap. They are not sensitive to water. Therefor, their use results in a sheet having excellent resistance to moisture.

[0026] The first filler material preferably provides at least 50 wt% of the sheet, and more preferably at least 60 wt% of the sheet, more preferably at least 65 wt% of the sheet, even more preferably at least 70 wt% of the sheet, even more preferably at least 75 wt% of the sheet.

[0027] The thermoset binder of the polymer matrix of a preferred sheet comprising a thermoset matrix or a combination of a thermoplastic matrix and a thermoset matrix, can be selected from aminoplast binders (e.g. urea formaldehyde, melamine formaldehyde, melamine urea formaldehyde), isocyanate binders (e.g. polymeric methylene diphenyl diisocyanate), polyurethane binders, acrylate binders, vinyl-acetate binders, epoxy binders, biobased binders, hyperbranched polyamide binders, or combinations thereof.

[0028] Thermoset binders which will form a thermoset matrix in the sheet can be applied in different ways. They can be added as particulate matter (e.g. melamine formaldehyde resin powder), or sprayed, or the first filler material and / or the second filler material can be coated with the thermoset binder. Two or more of these methods can be combined, wherein the thermoset binders applied in the different methods of application can be the same or different.

[0029] The thermoset matrix in the sheet can be a partially cured thermoset binder. Such embodiment has the benefit that the partially cured thermoset binder can be used as adhesive when laminating the sheet onto a board and / or when laminating a decorative top layer onto the sheet.

[0030] The low density particles can be selected from cork particles, polyurethane foam particles, thermoplastic foam particles, expanded glass, or combinations thereof.

[0031] The low density particles contribute to the sound dampening properties of the sheet. However, they can result in low impact resistance, reason why the combination is made with the first filler material such that a sheet with sufficient impact resistance is obtained for being used as floor covering or as layer in a floor covering, e.g. in a decorative floor panel.

[0032] The low density particles preferably provide at least 5 wt%, and preferably less than 30 wt% of the sheet. More preferably, the low density particles provide at least 10 wt% of the sheet, and more preferably at least 15 wt% of the sheet. More preferably, the low density particles provide less than 25 wt% of the sheet. Such embodiments provide an excellent combination of sound dampening and impact resistance of the sheet and of floor coverings comprising such sheet.

[0033] A preferred sheet is characterized in that the first filler material and the second filler material are each substantially uniformly distributed in the polymer matrix. Such substantial uniform distribution is beneficial for sound dampening and impact resistance of the sheet and of floor coverings comprising such sheet.

[0034] In sheets wherein the polymer matrix is a thermoplastic matrix or a combination of a thermoplastic matrix and a thermoset matrix, the thermoplastic polymer of the thermoplastic matrix or the thermoplastic polymer of the combination of the thermoplastic matrix and the thermoset matrix can be selected from polyvinyl butyral

[0035] (PVB), polylactic acid (PLA), ethylene vinyl acetate (EVA), polyamide, polyester (e.g. polyethylene terephthalate), polypropylene (PP), polyethylene (PE), polyvinyl chloride

[0036] (PVC), thermoplastic polyurethane or combinations thereof.

[0037] The use of polyvinyl butyral (PVB) is particularly preferred as its use provides optimum sound dampening properties.

[0038] The sheet can comprise at its bottom side an adhesion layer. Such adhesion layer can contact the polymer matrix in which the first filler material and the second filler material are embedded.

[0039] The adhesion layer is beneficial for laminating the sheet to a board, e.g. in the production process of a floor panel.

[0040] The adhesion layer preferably covers the full bottom surface of the sheet.

[0041] The adhesion layer can be provided by a thermoset resin, and more preferably by a partially cured thermoset resin. Preferred thermoset resins for use as or in the adhesion layer are aminoplast resins (e.g. urea formaldehyde, melamine formaldehyde, melamine urea formaldehyde) or polyurethane resins.

[0042] Aminoplast resins for use as or in the adhesion layer are particularly preferred when the sheet is to be laminated to a wood-based board, e.g. to a wood fiber board, to a wood particle board, to a plywood board or to an oriented strand board (OSB).

[0043] The upper side of the sheet can comprise a printed decor. The printed decor can be applied on an ink receiving coating layer applied onto the polymer matrix in which the first filler material and the second filler material are embedded. The printed decor can be a digitally printed decor.

[0044] A preferred sheet is between 0.5 and 3 mm thick. Such embodiments are ideally suited for being laminated onto a board. The board can act as carrier for the sheet, and a decorative top layer can be applied on the sheet.

[0045] A preferred sheet is between 3.5 and 7 mm thick. Such embodiments are ideally suited when the sheet itself, with addition of a decorative top layer and an optional balancing layer at the bottom of the sheet, is used as decorative panel, e.g. as decorative floor panel.

[0046] Preferred sheets can comprise a first layer and a second layer. The second layer is provided closer to the upper side of the sheet than the second first layer. The first layer and the second layer are part of the polymer matrix in which the first filler material and the second filler material are embedded.

[0047] The composition of the first layer can differ from the composition of the second layer. This way, the properties of the sheet can be optimized. The first layer can be optimized for being laminated to a board, whereas the second layer can be optimized for impact resistance. The first layer can comprise a larger amount by weight of polymer matrix material than the second layer. Such embodiment is beneficial, as laminating the sheet to a board is facilitated. Preferably, the first layer comprises a larger amount by weight of thermoset matrix material than the second layer.

[0048] It is preferred however that the polymer matrix material of the first layer and the matrix material of the second layer at least comprise the same thermoset binder and / or the same thermoplastic binder. Such embodiments are favored for their excellent adhesion between the first layer and the second layer.

[0049] The number based average particle size of the first filler material and / or of the second filler material can be smaller in the second layer than in the first layer. It is a benefit of such sheets that a better quality of decorative top layer can be created on such sheets, as there is less risk of telegraphing of coarse particles of the sheet through the decorative top layer.

[0050] The percentage by weight of the second filler material can be lower in the second layer than in the first layer. Such embodiment is beneficial for improving the impact resistance of the board.

[0051] Two or more of the listed features for the first layer and for the second layer can be combined as long as not contradictory.

[0052] Besides a first layer and a second layer, the sheet can comprise a third layer; wherein the third layer is part of the polymer matrix in which the first filler material and the second filler material are embedded; wherein the second layer is provided between the first layer and the third layer. The composition of the first layer and of the third layer is substantially the same.

[0053] Such embodiment has the benefit of a balanced layered composition, meaning that a sheet with excellent dimensional stability is obtained. As an example, the risk of cupping is minimal. The second layer preferably contacts the first layer and the third layer.

[0054] The first layer as well as the second layer of the embodiments described so far comprise first filler material as well as second filler material in the polymer matrix. However, it is also possible that these embodiments are modified in that the first layer or the second layer does not comprise second filler material embedded in the polymer matrix. It is meant that either the first layer or the second layer does not comprise low density particles having a density less than 0.30 g / cm3.

[0055] Such embodiments provide further opportunity for optimizing the properties and performance of the sheet, and of decorative panels comprising such sheets.

[0056] The second aspect of the invention is a decorative panel. The decorative panel comprises a sheet as in any embodiment of the first aspect of the invention, a printed decor and a wear layer. The printed decor is applied on the sheet.

[0057] The decorative panel can be used as decorative floor panel. The floor panel has sound dampening properties when being walked upon, while the impact properties of the floor panel are still good. The favorable combination of properties is obtained thanks to the combination of the first filler material and the second filler material in the sheet.

[0058] The printed decor can comprise a decor printed on the sheet. The decor can be printed on an ink receiving coating layer applied onto the polymer matrix in which the first filler material and the second filler material are embedded. The decor can have been printed with digital printing technologies, e.g. with digital inkjet printing technology.

[0059] The printed decor can comprise a resin impregnated printed sheet of paper laminated onto the sheet of the first aspect of the invention.

[0060] The resin impregnated printed sheet of paper can be laminated onto the sheet by the resin with which the resin impregnated printed sheet of paper is impregnated. It means that the resin impregnated sheet of paper can be laminated to the sheet in a Direct Pressure Lamination Process.

[0061] The resin impregnated printed sheet of paper can be glued onto the sheet by using an additional glue layer. To this end, the resin impregnated printed sheet of paper can be part of a High Pressure Laminate (HPL) which is glued onto the sheet by using an appropriate glue. A High Pressure Laminate comprises a resin impregnated printed sheet of paper laminated using thermoset resin on one or a plurality of Kraft paper layers.

[0062] The decorative panel comprises a wear layer. In a preferred embodiment, the wear layer comprises an alpha cellulose sheet of paper impregnated with resin, e.g. impregnated with aminoplast resin (e.g. with a melamine formaldehyde resin), impregnated with an acrylate resin or impregnated with a polyurethane resin.

[0063] Such alpha cellulose sheet of paper impregnated with resin can be laminated in a same lamination operation as resin impregnated printed sheet of paper onto the sheet of the first aspect of the invention. Alternatively, the alpha cellulose sheet of paper impregnated with resin can have been integrated in the already mentioned High Pressure Laminate.

[0064] The alpha cellulose sheet of paper impregnated with resin can comprise wear resistance increasing particles, such as corundum, diamond, or silicon carbide.

[0065] In a preferred embodiment of the invention, the wear layer comprises or consists of a coating layer. The coating layer can be an acrylate coating layer (e.g. a polyurethane acrylate coating layer), a thermoset polyester coating layer, or a polyurethane coating layer.

[0066] The coating layer can comprise wear resistance increasing particles, such as corundum, diamond, or silicon carbide.

[0067] The decorative panel can comprise an embossed surface. The embossments can be provided in register with the printed decor. Preferably, at least part of the embossments at the embossed surface also show a deformation of the polymer matrix of the sheet.

[0068] The sheet of the invention enables that deep embossments can be provided in the surface of the decorative panel. The provision of the second filler material facilitates the formation of deep embossments.

[0069] The decorative panel of the invention can be provided with a pressed bevel, wherein in the pressed bevel, there is a deformation of the polymer matrix of the sheet by pressing the bevel.

[0070] The decorative panel can be rectangular, square or oblong, wherein the decorative panel comprises at a first pair of opposite edges coupling parts for coupling two such panels at their edges, wherein in coupled condition a locking is obtained in the direction parallel with the plane of the coupled decorative panels and perpendicular to the coupled edges, and / or a locking is obtained in the direction perpendicular to the plane of the coupled decorative panels.

[0071] The coupling parts can be provided substantially entirely in the sheet. Alternatively, the coupling parts can be provided substantially in the board onto which the sheet is laminated. It is also possible that the coupling parts are provided partly in the sheet and partly in the board onto which the sheet is laminated.

[0072] Providing the coupling parts substantially entirely in a board onto which the sheet is laminated provides the coupling parts with high strength and appropriate properties for appropriate coupling of the decorative panels.

[0073] A preferred decorative panel is characterized in that the sheet is between 3.5 and 7 mm thick, wherein the sheet provides at least 80% - and more preferably at least 90% - of the thickness of the decorative panel. More preferably, such preferred decorative panel consists of the sheet, a top layer comprising the printed decor and the wear layer, and optionally a balancing layer at the bottom of the decorative panel. The optional balancing layer can be laminated onto the polymer matrix in which the first filler material and the second filler material is embedded.

[0074] Such embodiments provide a simple layered construction of the decorative panel, which facilitates its production.

[0075] The bottom surface of the polymer matrix of the sheet - polymer matrix in which the first filler material and the second filler material are embedded - can provide the bottom surface of the decorative panel; possibly except for a balancing layer at the bottom surface of the polymer matrix of the sheet.

[0076] The balancing layer can be provided by a resin impregnated sheet of paper, or by a balancing sealer coating.

[0077] A preferred decorative panel of the second aspect of the invention is characterized in that the sheet is laminated to a board, wherein the board provides at least 60% (and preferably at least 70%) of the thickness of the decorative panel.

[0078] The board acts as a carrier for the sheet, and can provide the decorative panel with specific mechanical properties. Coupling parts can be milled in the board.

[0079] Examples of boards that can be used in the invention are wood-based boards (e.g. wood fiber boards, wood chip boards, oriented strand boards or plywood boards), mineral based boards (gypsum boards, magnesium oxide (MgO) based boards or cement boards), or - whether or not filled - polymer boards (e.g. whether or not filled polyvinyl chloride based boards). The decorative panel can comprise an adhesion layer provided between the board and the sheet. Such adhesion layer improves the adhesion between the board and the sheet of the first aspect of the invention.

[0080] A preferred decorative panel comprises a balancing layer. The balancing layer can be selected from one or more of a resin impregnated sheet of paper or a balancing sealer coating, such as an acrylate, an aminoplast or a polyurethane based coating.

[0081] The balancing layer is beneficial for providing dimensional stability to the decorative panel, e.g. to ensure straightness and flatness to the decorative panel. The balancing layer can provide resistance to cupping of the decorative panel.

[0082] Use of a balancing sealer coating is preferred when the wear layer comprises or consists of a coating layer. The balancing sealer coating can be a UV-cured acrylate coating layer, e.g. a UV-cured polyurethane acrylate coating layer.

[0083] The third aspect of the invention is a method for producing a sheet as in the first aspect of the invention. The method comprises the steps of:

[0084] - providing a particulate blend comprising first filler material, second filler material, and optionally particulate polymer binder;

[0085] - scattering the particulate blend in one or more than one consecutive scattering operation(s);

[0086] - optionally spraying polymer binder - preferably thermoset binder - onto the particulate blend before, during or after the scattering;

[0087] - consolidating the scattered particulate blend using a press operation, thereby forming a sheet comprising a polymer matrix, a first filler material and a second filler material; wherein the first filler material and the second filler material are embedded in the polymer matrix; wherein the first filler material is selected from wood material, plant-based material, mineral fillers, or combinations thereof; wherein the second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3; wherein the polymer matrix is selected from a thermoplastic polymer matrix, a thermoset polymer matrix; or combinations thereof.

[0088] The method of the third aspect of the invention can be used to manufacture a sheet according to the first aspect of the invention. The first filler material, the second filler material and the thermoset and / or thermoplastic binders used for forming the polymer matrix can be as specified in the listed embodiments of the sheet of the first aspect of the invention.

[0089] In the method, the polymer matrix can be obtained via the introduction of particulate polymer binder (particulate thermoplastic polymer binder and / or particulate thermoset polymer binder) and / or of thermoset binder applied in another way. Liquid thermoset binder can be added by a spraying operation during the scattering process, such that thermoset binder is distributed between the first filler material and the second filler material. It is also possible that the first filler material and / or the second filler material are coated with thermoset binder.

[0090] In the pressing operation, the polymer matrix will be formed. The polymer matrix will be - depending on the polymer binder used - be a thermoplastic matrix, a thermoset matrix or a combination of a thermoplastic and a thermoset matrix.

[0091] A combination of a thermoplastic matrix and a thermoset matrix can be an interconnected network of a thermoplastic and a thermoset matrix. Alternatively, the polymer matrix can be in part thermoset in nature and in part thermoplastic in nature, as is e.g. achieved when the first filler material has been coated with a thermoset binder and thermoplastic binder particles have been blended together with the first filler material and the second filler material in order to be scattered together.

[0092] The pressing operation is preferably performed at increased temperature. The increased temperature can be selected as required for forming the polymer matrix. The pressing operation can also be performed at ambient temperature, meaning without increasing the temperature, e.g. when cold curing polyurethane resin is used for forming the polymer matrix.

[0093] The pressing operation can be performed in a double belt press, however, other types of press operations can be used.

[0094] As mentioned above, the sheet can comprise a first layer and a second layer, and even a third layer. Such sheets can be made according to a method according to the third aspect of the invention in which consecutively different particulate blends are scattered, such that the different layers are formed prior to the pressing operation. Such scattering can be combined with spraying liquid thermoset binder during the scattering operation.

[0095] Therefore, a preferred method according to the third aspect of the invention is characterized in that the step of scattering the particulate blend comprises the step of first scattering a first particulate blend followed by scattering a second particulate blend. The first particulate blend as well as the second particulate blend comprises first filler material, second material, and optionally particulate polymer binder. The composition of the first particulate blend differs from the composition of the second particulate blend. The sheet obtained comprises a first layer and a second layer, wherein the first layer is obtained from the first particulate blend and the second layer is obtained from the second particulate blend.

[0096] The first particulate blend and the second particulate blend can be composed for producing the layered sheets described earlier in the invention.

[0097] It is also possible that the first particulate blend or the second particulate blend do not comprise second filler material. Such embodiments allow to tune the properties of the sheet. A preferred method of the third aspect of the invention is characterized in that the scattering is performed on a board, and that in the consolidation step the sheet obtained is laminated onto the board.

[0098] To this end, the board can be provided with an adhesion layer to facilitate the adhesion of the sheet to the board in the pressing operation.

[0099] The fourth aspect of the invention is a method for producing a sheet as in the first aspect of the invention. The method comprises the steps of

[0100] - providing a particulate blend comprising first filler material, second filler material, and optionally particulate polymer binder;

[0101] - scattering the particulate blend in or on a mold, thereby obtaining a scattered particle blend in or on the mold;

[0102] - optionally spraying polymer binder - preferably thermoset binder - onto the particulate blend during the scattering;

[0103] - consolidating the scattered particulate blend in or on the mold using a press operation, thereby forming a mass comprising a polymer matrix, the first filler material and the second filler material, wherein the first filler material and the second filler material are embedded in the polymer matrix;

[0104] - slicing the mass thereby obtaining a sheet comprising a polymer matrix, the first filler material and the second filler material, wherein the first filler material and the second filler material are embedded in the polymer matrix; wherein the first filler material is selected from wood material, plant-based material, mineral fillers, or combinations thereof; wherein the second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3; wherein the polymer matrix is selected from a thermoplastic polymer matrix, a thermoset polymer matrix, or combinations thereof.

[0105] The slicing operation can be performed linearly. The slicing operation can be performed circumferentially, e.g. from material in cylindrical shape. A circumferential slicing operation can result is sheets of larger length than a linear slicing operation.

[0106] The same possible approaches apply with respect to the formation of the polymer matrix (and the thermoplastic and / or thermoset binders used for forming the polymer matrix) as for the method of the third aspect of the invention.

[0107] The method of the fourth aspect of the invention provides an alternative production method for producing a sheet according to the third aspect of the invention. The method of the fourth aspect of the invention is of particular interest for producing smaller volumes of sheet, e.g. for sample production.

[0108] The pressing operation is preferably performed at increased temperature. The increased temperature can be selected as required for forming the polymer matrix.

[0109] The pressing operation can also be performed at ambient temperature, meaning without increasing the temperature, e.g. when cold curing polyurethane resin is used for forming the polymer matrix.

[0110] In preferred methods of the third aspect or of the fourth aspect of the invention, the scattering operation results in a substantially homogeneous scattered particle blend.

[0111] In the methods of the third aspect and of the fourth aspect of the invention, the first filler material, the second filler material and the polymer matrix can have features as specified for the sheet of the first aspect of the invention.

[0112] With the intention of better showing the characteristics of the invention, hereafter, as an example without any limitative character, several preferred embodiments are described, with reference to the accompanying drawings, wherein: figure 1 shows an embodiment of a sheet according to the first aspect of the invention; figure 2 shows another embodiment of a sheet according to the first aspect of the invention; figure 3 shows yet another embodiment of a sheet according to the first aspect of the invention; figure 4 shows an embodiment of a decorative panel according to the second aspect of the invention; figure 5 shows an embodiment of a decorative panel according to the second aspect of the invention; figure 6 shows an example of a method according to aspects of the invention; and figure 7 shows an example of a method according to aspects of the invention.

[0113] Figure 1 shows an embodiment of a sheet 10 according to the invention. The sheet comprises a polymer matrix 11, a first filler material 12 and a second filler material 14. The first filler material 12 is selected from wood material, plant-based material, mineral fillers, or combinations thereof. The second filler material 14 is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3. The first filler material 12 as well as the second filler material 14 are embedded in the polymer matrix 11.

[0114] The sheet 10 optionally comprises at its bottom side an adhesion layer 16. The adhesion layer 16 can be a partially cured thermoset resin, e.g. a partially cured aminoplast resin (e.g. a urea formaldehyde resin) or a polyurethane resin. The adhesion layer can be beneficial for laminating the sheet 10 to a board, e.g. in the production process of a decorative floor panel according to the second aspect of the invention.

[0115] The polymer matrix 11 is selected from a thermoplastic matrix, a thermoset matrix, or combinations thereof.

[0116] The first filler material 12 can comprise or consist of wood material (e.g. wood fibers or wood particles; or combinations thereof). The wood fibers and / or the wood particles can be coated with a thermoset binder. This way, the thermoset binder will form the polymer matrix or be part in it. It is e.g. possible to combine in the production process of the sheet particulate thermoplastic binder material with wood fibers or wood particles coated with a thermoset binder and second filler material in order to create a polymer matrix which is a combination of a thermoplastic binder and a thermoset binder.

[0117] Other ways of applying the thermoset binder are also possible, the thermoset binder can e.g. be applied as particulate matter (e.g. as melamine formaldehyde resin powder) or by spraying liquid thermoset binder when scattering the particulate matter in the process of formation of the sheet.

[0118] Besides or in combination with wood material, the first filler can comprises or consist of plant-based material (e.g. flax shives or miscanthus particles) or mineral fillers, such as calcium carbonate, talcum, fly ash, magnesium oxide, grit, kaolinite, or combinations thereof.

[0119] Cork particles, polyurethane foam particles, thermoplastic foam particles, expanded glass, or combinations thereof, are examples of low density particles of the second filler that can be used.

[0120] Figure 2 shows another embodiment of a sheet 20 according to the first aspect of the invention. The sheet 20 comprises a first layer 27 and a second layer 28. The first layer 27 and the second layer 28 are part of the polymer matrix in which the first filler material and the second filler material are embedded.

[0121] The first layer 27 comprises polymer matrix material 21, first filler material 22 and second filler material 24. The first filler material 22 of the first layer 27 is selected from wood material, plant-based material, mineral fillers, or combinations thereof. The second filler material 24 of the first layer 27 is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3. The first filler material 22 of the first layer 27 as well as the second filler material 24 of the first layer 27 are embedded in the polymer matrix 21 of the matrix material of the first layer 27. The second layer 28 comprises polymer matrix material 31, first filler material 32 and second filler material 34. The first filler material 32 of the second layer 28 is selected from wood material, plant-based material, mineral fillers, or combinations thereof. The second filler material 34 of the second layer 28 is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3. The first filler material 32 of the second layer 28 as well as the second filler material 34 of the second layer 28 are embedded in the polymer matrix 31 of the matrix material of the second layer 29.

[0122] The combination of the polymer matrix material 21 of the first layer 27 and the polymer matrix material 31 of the second layer 28 provides the polymer matrix of the sheet 20 of figure 2.

[0123] In order to optimize the properties and the performance of the sheet, the matrix materials 31, 32; the first filler materials 22, 32; and / or the second filler materials 24, 34 of the first layer 27 and the second layer 28 can differ in composition and / or in relative content.

[0124] It is preferred that the polymer matrix material 21 of the first layer 27 and the polymer matrix material 31 of the second layer 28 at least comprise the same thermoset binder and / or the same thermoplastic binder; which is beneficial for the adhesion between the first layer 27 and the second layer 28 of the sheet 20.

[0125] The sheet 20 of figure 2 optionally comprises at its bottom side an adhesion layer 16. Such adhesion layer is beneficial for laminating the sheet to a carrier, e.g. to a board for producing a floor panel.

[0126] Figure 3 shows another embodiment of a sheet 30 according to the first aspect of the invention. The sheet 30 comprises a first layer 27 and a second layer 28 as in the example shown in figure 2. The reference numerals in figure 3 have the same meaning as in figure 2. In addition, the sheet 30 of figure 3 comprises a third layer 29. In the example shown in figure 3, the third layer 29 has the same thickness and the same composition as the first layer 27. This is however not necessarily the case for the invention.

[0127] Sheets wherein the first layer 27 and the third layer 29 have the same thickness and the same composition have a balanced layer composition resulting in excellent dimensional stability of the sheet.

[0128] Figure 4 shows an example of a decorative panel 40 according to the second aspect of the invention. The decorative panel 40 of the example of figure 4 can be used as decorative floor panel. The decorative panel 40 comprises a sheet 10 according to the first aspect of the invention, e.g. a sheet as shown in figure 1. However, also sheets as shown in figures 2 and 3 can be used. The reference numerals in figure 4 have the same meaning as in the other figures. The sheet 10 is laminated onto a board 42.

[0129] The board 42 can be a wood-based board, e.g. a wood fiber board, a wood particle board, a plywood board or an oriented strand board (OSB). The board can also be a mineral based board (e.g. a gypsum board, a magnesium oxide (MgO) based board or a cement board) or a - whether or not filled - polymer board, e.g. a filled polyvinyl chloride based board.

[0130] The decorative panel 40 of the example shown further comprises a printed decor 44 and a wear layer 46.

[0131] In the example of figure 4, the sheet 10 has thickness T1 of 2 mm and the board 42 has thickness T2 of 8 mm.

[0132] In the example shown, the printed decor 44 is provided by a resin impregnated printed sheet of paper laminated onto the sheet 10. In the example shown, the wear layer 46 is provided by a resin impregnated sheet of alpha cellulose paper. Other ways of applying the printed decor and the wear layer are possible according to the invention. The surface of the decorative panel 40 is provided with embossments. The embossments can be applied in register with the printed decor, e.g. for the decorative panel to simulate a wood plank.

[0133] The decorative panel 40 of the example of figure 4 comprises a balancing layer 48 laminated to the bottom of the board 42. In the example shown, the balancing layer 48 is provided by a resin impregnated sheet of paper.

[0134] The decorative panel 40 is provided with pressed bevels 49. In the pressed bevels 49, there is a deformation of the polymer matrix 11 of the sheet 10 created by pressing the bevels 49.

[0135] The decorative panel 40 of figure 4 is rectangular and is provided at a first pair of opposite edges with coupling parts for coupling two such decorative panels at their edges. The coupling parts are configured such that in coupled condition a locking is obtained in the direction parallel with the plane of the coupled decorative panels and perpendicular to the coupled edges, as well as in the direction perpendicular to the plane of the coupled decorative panels.

[0136] In the decorative panel 40 of figure 4, the coupling parts are configured as on the one hand a tongue 51 and on the other hand a female coupling part provided by a groove 52 bordered by an upper lip 53 and a lower lip 54. The tongue 51 on the one hand and on the other hand the groove 52 bordered by the upper lip 53 and the lower lip 54 provide in coupled condition a locking in the direction perpendicular to the surface of the coupled decorative panels. The tongue 51 and the female coupling part comprise locking parts 56, 57. The locking parts 56, 57 provide in coupled condition a locking in the direction perpendicular to the coupled edges and parallel to the surface of the coupled decorative panels. In the example, the coupling parts comprise a protrusion 56 at the lower lip 54 and a corresponding recess 57 at the bottom of the tongue 51.

[0137] In the example of figure 4, the coupling parts are substantially provided in the board 42. The second pair of opposite edges can also be provided with coupling parts which can be the same as, similar to, or different in nature from the coupling parts at the first pair of opposite edges of the decorative panel.

[0138] Figure 5 shows another embodiment of a decorative panel 40 according to the second aspect of the invention. The decorative panel 40 of figure 5 consists of a sheet 10 according to the first aspect of the invention (e.g. the sheet 10 shown in figure 1), a top layer comprising the printed decor 44 and the wear layer 46, and optionally a balancing layer 48 at the bottom of the decorative panel. The optional balancing layer 48 can be laminated onto the polymer matrix 11 in which the first filler material 12 and the second filler material 14 is embedded. The reference numerals in figure 5 have the same meaning as in the other figures.

[0139] The decorative panel 40 of figure 5 is provided with coupling parts. The coupling parts of the decorative panel 40 of figure 5 are configured similarly to the coupling parts of the decorative panel of figure 4. The coupling parts of the decorative panel of figure 5 are provided substantially entirely in the sheet 10.

[0140] The sheet 10 of the decorative panel 50 of figure 4 can e.g. have a thickness T3 between 3.5 and 7 millimeter.

[0141] Figure 6 illustrates a method for producing a sheet according to the first aspect of the invention. After blending first filler material, second filler material and optionally particulate polymer binder, the obtained particulate blend 61 is scattered in one or more than one consecutive scattering operations onto a belt 67. In the example, two consecutive scattering units 61 are shown for scattering the particulate blend 62. Figure 6 shows that the same particulate blend 61 is scattered in both scattering units 62. This way, a gradual built up of the required amount of particulate blend is obtained.

[0142] However, it is possible that the two (or more than two) scattering units 62 scatter different particulate blends for producing multi-layered sheets according to the invention. Instead of scattering on a belt, the particulate blend can be scattered on a board, in order to obtain a sheet laminated to a board in the same process in which the sheet is manufactured.

[0143] Polymer binder material, preferably liquid thermoset binder 64, can be sprayed onto the particulate blend during or after the scattering. To this end, figure 6 shows two spraying units 65 for spraying liquid thermoset binder 64 onto the scattered particulate blend. Instead or in addition, it is possible to spray binder on the particulate blend before the scattering operation.

[0144] The scattered particulate blend, with the polymer binder, is consolidated in a double-belt press 68, thereby forming the sheet 10 which comprises a polymer matrix, a first filler material and a second filler material; wherein the first filler material and the second filler material are embedded in the polymer matrix. The consolidation in the double-belt press 68 can be performed at increased temperatures. The temperature can be selected based on e.g. the type of polymer binders used for forming the polymer matrix of the sheet. Other types of presses can be used than a double-belt press.

[0145] The first filler material can be selected from wood material, plant-based material, mineral fillers, or combinations thereof. The second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3.

[0146] The polymer matrix can be selected from a thermoplastic polymer matrix, a thermoset polymer matrix; or combinations thereof.

[0147] The polymer matrix can be obtained in several ways. A way for obtaining a thermoplastic polymer matrix, or of introducing a thermoplastic polymer binder in a combined thermoplastic and thermoset polymer matrix, is by blending in the particulate blend particles of thermoplastic material which will fuse when consolidating the particulate blend at increased temperature. Ways for obtaining a thermoset polymer matrix, or of introducing a thermoset polymer binder in a combined thermoplastic and thermoset polymer matrix include: coating the first filler material and / or the second filler material with thermoset binder; spraying liquid thermoset binder during or after the scattering process onto the scattered particulate blend; and

[0148] - blending solid particles of thermoset binder (e.g. solid particles of a urea formaldehyde resin) in the particulate blend.

[0149] Figure 7 shows an example of a method according to the fourth aspect of the invention for producing a sheet according to the first aspect of the invention.

[0150] Referring to figure 7a) a particulate blend comprising first filler material, second filler material, and optionally particulate polymer binder is scattered in or on a mold 71 thereby forming a scattered particulate blend 75. To this end, figure 7 shows a travelling scattering unit 62. Optionally, polymer binder 64 can be sprayed during the scatting of the particulate blend using a travelling spraying unit 65.

[0151] As shown in figure 7b) the scattered particulate blend is consolidated in or on the mold 71 using a press operation in a press 73. This way, a mass 75 is formed comprising a polymer matrix, the first filler material and the second filler material, wherein the first filler material and the second filler material are embedded in the polymer matrix.

[0152] The polymer matrix can be composed and obtained in the same way as described for the method shown in figure 6.

[0153] The mass 75 is sliced in a slicing operation (see figure 7c) using slicing equipment 77, thereby obtaining a sheet 80 comprising a polymer matrix, the first filler material and the second filler material, wherein the first filler material and the second filler material are embedded in the polymer matrix. The following table presents examples of recipes for producing a sheet according to aspects of the invention:

[0154] Sheets made with these recipes provided good sound dampening properties when used in a decorative floor panel. Decorative floor panels according to the invention incorporating these sheets had good impact properties. It was observed that the sheets made with the higher amount of thermoset resin resulted in decorative floor panels having higher impact resistance. A higher amount of cork in the sheets improved the sound dampening properties of the decorative floor panels even more.

[0155] The thermoset resin can be applied as a coating on the wood particles, and optionally also as a coating on the cork particles. Alternatively, it can be sprayed during the scattering process in which the particulate blend of the wood particles, the cork particles and the polyvinyl butyral (PVB) particles are scattered.

[0156] The examples list polyvinyl butyral as thermoplastic binder. However, other thermoplastic binders can be used, e.g. polylactic acid (PLA), ethylene vinyl acetate (EVA), polyamide, polyester (e.g. polyethylene terephthalate), polypropylene (PP), polyethylene, polyvinyl chloride, thermoplastic polyurethane or combinations thereof. Although the examples in the table mention cork particles as second filler material, other second filler material can be used, such as polyurethane foam particles, thermoplastic foam particles, expanded glass, or combinations thereof. The present invention is in no way limited to the embodiments described as examples and represented in the figures, on the contrary it can be realized in various forms and dimensions, without leaving the scope of the invention.

Claims

Claims1.- A sheet, characterized in that the sheet comprises a polymer matrix, a first filler material and a second filler material; wherein the first filler material is selected from wood material, plant-based material, mineral fillers, or combinations thereof; wherein the second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3; wherein the first filler material as well as the second filler material are embedded in the polymer matrix; wherein the polymer matrix is selected from a thermoplastic matrix, a thermoset matrix, or combinations thereof.2.- A sheet as in claim 1, characterized in that the first filler material comprises wood fibers or wood particles, or combinations thereof; and / or that the first filler material comprises plant-based particles; or combinations thereof.3.- A sheet as in claim 2, characterized in that the wood fibers, the wood particles or the plant-based particles are coated with a thermoset binder.4.- A sheet as in any of the preceding claims, characterized in that the first filler material comprises one or more of calcium carbonate, talcum, fly ash, magnesium oxide, grit, or kaolinite.5.- A sheet as in any of the preceding claims, characterized in that the first filler material provides at least 50 wt%, and more preferably at least 60 wt%, of the sheet.6.- A sheet as in any of the preceding claims, characterized in that the sheet comprises a thermoset matrix or a combination of a thermoplastic matrix and a thermoset matrix, wherein the thermoset binder of the thermoset matrix or of the combination of a thermoplastic matrix and a thermoset matrix is selected from an aminoplast binder, an isocyanate binder, a polyurethane binder, an acrylate binder, a vinyl-acetate binder, anepoxy binder, a biobased binder, a hyperbranched polyamide binder; or combinations thereof.7.- A sheet as in any of the preceding claims, characterized in that the low density particles are selected from cork particles, polyurethane foam particles, thermoplastic foam particles, expanded glass, or combinations thereof.8.- A sheet as in any of the preceding claims, characterized in that the low density particles provide at least 5 wt%, and more preferably at least 10 wt% of the sheet, and preferably less than 30 wt% of the sheet, more preferably less than 25 wt% of the sheet.9.- A sheet as in any of the preceding claims, characterized in that the first filler material and the second filler material are each substantially uniformly distributed in the polymer matrix.10.- A sheet as in any of the preceding claims, characterized in that the polymer matrix is a thermoplastic matrix or a combination of a thermoplastic matrix and a thermoset matrix, wherein the thermoplastic polymer of the thermoplastic matrix or of the combination of the thermoplastic matrix and the thermoset matrix, is selected from polyvinyl butyral (PVB), polylactic acid (PLA), ethylene vinyl acetate (EVA), polyamide, polyester (e.g. polyethylene terephthalate), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), thermoplastic polyurethane or combinations thereof.11.- A sheet as in any of the preceding claims, characterized in that the sheet comprises at its bottom side an adhesion layer, preferably wherein the adhesion layer is provided by a thermoset resin and / or preferably wherein the adhesion layer covers the full bottom surface of the sheet.12.- A sheet as in any of the preceding claims, characterized in that the upper side of the sheet comprises a printed decor, preferably wherein the printed decor is applied on an ink receiving coating layer applied onto the polymer matrix in which the first filler material and the second filler material are embedded.13.- A sheet as in any of the preceding claims, characterized in that the sheet is between 0.5 and 3 mm thick.14.- A sheet as in any of the preceding claims, characterized in that the sheet is between 3.5 and 7 mm thick.15.- A sheet as in any of the preceding claims, characterized in that the sheet comprises a first layer and a second layer, wherein the second layer is provided closer to the upper side of the sheet than the first layer; wherein the first layer and the second layer are part of the polymer matrix in which the first filler material and the second filler material are embedded; wherein the sheet comprises one or more of the following features:- the composition of the first layer differs from the composition of the second layer;- the first layer comprises a larger amount by weight of polymer matrix material than the second layer;- the number based average particle size of the first filler material and / or of the second filler material is smaller in the second layer than in the first layer;- the percentage by weight of the second filler material is lower in the second layer than in the first layer.16.- A sheet as in claim 15, characterized in that the sheet comprises a third layer; wherein the third layer is part of the polymer matrix in which the first filler material and the second filler material are embedded; wherein the second layer is provided between the first layer and the third layer - preferably wherein the second layer contacts the first layer and the third layer -; wherein the composition of the first layer and the third layer is substantially the same.17.- Decorative panel, characterized in that the decorative panel comprises a sheet as in any of the preceding claims 1 - 16, a printed decor and a wear layer; wherein the printed decor is applied on the sheet.18.- Decorative panel as in claim 17, characterized in that the printed decor comprises a decor printed on the sheet, preferably onto an ink receiving coating layer applied onto the polymer matrix in which the first filler material and the second filler material are embedded.19.- Decorative panel as in claim 17, characterized in that the printed decor comprises a resin impregnated printed sheet of paper laminated onto the sheet, preferably wherein the resin impregnated printed sheet of paper is laminated onto the sheet by the resin with which the resin impregnated printed sheet of paper is impregnated.20.- Decorative panel as in any of the preceding claims 17 - 19, characterized in that the wear layer comprises an alpha cellulose sheet of paper impregnated with resin, e.g. impregnated with an aminoplast resin, impregnated with an acrylate resin or impregnated with a polyurethane resin.21.- Decorative panel as in any of the preceding claims 17 - 20, characterized in that the wear layer comprises or consists of a coating layer - e.g. an acrylate coating layer, a thermoset polyester coating layer or a polyurethane coating layer -, optionally comprising wear resistance increasing particles.22.- Decorative panel as in any of the preceding claims 17 - 21, characterized in that the decorative panel is rectangular, square or oblong; wherein the decorative panel comprises at a first pair of opposite edges coupling parts for coupling two such panels at their edges, wherein in coupled condition a locking is obtained in the direction parallel with the plane of the coupled panels and perpendicular to the coupled edges; and / or a locking is obtained in the direction perpendicular to the plane of the coupled panels.23.- Decorative panel as in any of the preceding claims 17 - 22, characterized in that the sheet is between 3.5 and 7 mm thick, wherein the sheet provides at least 80% of the thickness of the decorative panel.24.- Decorative panel as in claim 23, characterized in that the bottom surface of the polymer matrix of the sheet - polymer matrix in which the first filler material and the second filler material are embedded - provides the bottom surface of the decorative panel; possibly except for a balancing layer at the bottom surface of the polymer matrix of the sheet.25.- Decorative panel as in any of the preceding claims 17 - 22, characterized in that the sheet is laminated to a board, wherein the board provides at least 60%, and preferably at least 70%, of the thickness of the decorative panel.26.- Decorative panel as in claim 25, characterized in that the decorative panel comprises an adhesion layer provided between the board and the sheet.27.- Decorative panel as in any of the preceding claims 17 - 26, characterized in that the decorative panel comprises a balancing layer, preferably wherein the balancing layer is selected from one or more of:- a resin impregnated sheet of paper; or- a balancing sealer coating, such as an acrylate coating, an aminoplast coating or a polyurethane based coating.28.- Method for producing a sheet as in any of the preceding claims 1 - 16, characterized in that the method comprises the steps of- providing a particulate blend comprising first filler material, second filler material, and optionally particulate polymer binder;- scattering the particulate blend in one or more than one consecutive scattering operation(s);- optionally spraying polymer binder - preferably thermoset binder - onto the particulate blend before, during or after the scattering;- consolidating the scattered particulate blend using a press operation - preferably at increased temperature - , e.g. in a double belt press, thereby forming a sheet comprising a polymer matrix, a first filler material and a second filler material, wherein the first filler material and the second filler material are embedded in the polymer matrix;wherein the first filler material is selected from wood material, plant-based material, mineral fillers, or combinations thereof; wherein the second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3; wherein the polymer matrix is selected from a thermoplastic polymer matrix, a thermoset polymer matrix, or combinations thereof.29.- Method as in claim 28, characterized in that the step of scattering the particulate blend comprises the step of first scattering a first particulate blend followed by scattering a second particulate blend; wherein the first particulate blend as well as the second particulate blend comprise first filler material, second material, and optionally particulate polymer binder; wherein the composition of the first particulate blend differs from the composition of the second particulate blend; wherein the sheet comprises a first layer and a second layer, wherein the first layer is obtained from the first particulate blend and the second layer is obtained from the second particulate blend.30.- Method as in claims 28 - 29, characterized in that said scattering is performed on a board; and that in the consolidation step the sheet obtained is laminated onto the board.31.- Method for producing a sheet as in any of the preceding claims 1 - 16, characterized in that the method comprises the steps of- providing a particulate blend comprising first filler material, second filler material, and optionally particulate polymer binder;- scattering the particulate blend in or on a mold, thereby obtaining a scattered particle blend in or on the mold;- optionally spraying polymer binder - preferably thermoset binder - onto the particulate blend during the scattering;- consolidating the scattered particulate blend in or on the mold using a press operation - preferably at increased temperature - thereby forming a mass comprising a polymer matrix, the first filler material and the second filler material, wherein the first fillermaterial and the second filler material are embedded in the polymer matrix;- slicing the mass thereby obtaining a sheet comprising a polymer matrix, the first filler material and the second filler material, wherein the first filler material and the second filler material are embedded in the polymer matrix; wherein the first filler material is selected from wood material, plant-based material, mineral fillers, or combinations thereof; wherein the second filler material is provided by low density particles, wherein the low density particles have a density less than 0.30 g / cm3; wherein the polymer matrix is selected from a thermoplastic polymer matrix, a thermoset polymer matrix, or combinations thereof.

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