Panel and method for producing a panel

Abstract

The board comprises a decorative paper layer impregnated with a resin, such as melamine formaldehyde resin, and a substrate. The decorative paper layer is bonded in the board by polyurethane.

Description

Technical Field

[0001] This invention relates to a board in which decorative paper is bonded to a board substrate in a more reliable manner. This decorative paper may have a uniform color or may have a decorative print. The invention also relates to a method for producing such a board. Background Technology

[0002] Commonly known are boards that include a substrate and a decoration, for example, in the form of MDF (medium-density fiberboard) or HDF (high-density fiberboard) (such as, for example, laminates described in WO97 / 47834), in the form of vinyl (such as, for example, in WO2013 / 026559), or in the form of so-called (wood-plastic composite) boards with a vinyl top layer (such as, for example, described in WO2014 / 065953).

[0003] Laminates of WO97 / 47834 include an MDF or HDF substrate to which a decorative layer is applied. This decorative layer comprises printed paper impregnated with melamine-formaldehyde resin. Laminates are produced by laminating the decorative layer onto the MDF or HDF substrate under elevated temperature and pressure, in which case the melamine-formaldehyde resin cures through a condensation reaction, thus ensuring adhesion between the decorative paper layer and the substrate. This condensation reaction results in the formation of water (which can be absorbed by the MDF or HDF substrate). Typically, during the same pressing process, an abrasion layer is laminated onto the printed paper layer. This abrasion layer is melamine-formaldehyde impregnated paper, which optionally includes abrasion-resistant particles (such as, for example, alumina particles). During the pressing operation, a texture can be pressed onto the surface of the board using a textured press plate.

[0004] The waterproof sheet from WO2013 / 026559 has a substrate made of PVC (polyvinyl chloride) (with a printed decorative layer made of PVC) and a wear-resistant layer made of PVC. The surface properties of this sheet are not as good as those of the sheet described in WO97 / 47834.

[0005] WO2011 / 003763A2 mentions the production of so-called compact board. This is a board consisting of a substrate composed of multiple phenolic resin-impregnated paper layers and a decorative top layer consisting of decorative paper layers impregnated with melamine-formaldehyde resin. The layers are pressed together under elevated temperature and pressure, in which case the phenolic resin and melamine-formaldehyde crosslink, resulting in adhesion between the layers. The disadvantage of this technique is that all layers must be pressed together. Adhesion is problematic when the phenolic resin-impregnated paper layers are pressed first and only the decorative paper layers are pressed onto the compressed phenolic resin layers. However, this method is attractive because it allows for the mass production of the base board at low cost, and decorative layers can be added only through subsequent pressing if needed.

[0006] WO2006 / 082509A2 relates to a sandwich panel made of three layers: a first outer layer, an intermediate layer, and a second outer layer. The intermediate layer is a thick and strong board formed by pressing individual phenolic resin-impregnated paper layers together at elevated temperatures. The first and second outer layers are thin and strong boards formed from differently impregnated paper layers and compressed at elevated temperatures. The sandwich panel is produced by applying an adhesive layer to the surface of the intermediate layer or to the inner surfaces of the first and second outer layers. Subsequently, the layers are pressed together. However, applying the adhesive layer to these strong outer layers or to the intermediate layer is an additional and complex step.

[0007] US9,611,659B2 describes a system comprising a waterproof PVC sheet and a melamine resin layer bonded to the waterproof PVC sheet via an adhesive layer. Furthermore, US9,611,659B2 describes a method for producing such a sheet, wherein a rigid cross-linked melamine sheet is bonded to the PVC sheet. A disadvantage of the method from US9,611,659B2 is that delamination of the adhesive layer may occur if the adhesive does not have sufficient resistance. Additionally, a large amount of adhesive is required to bond the melamine resin layer to the sheet, resulting in increased sheet thickness and cost.

[0008] US 8,956,714B2 discloses a waterproof sheet and a method for producing a waterproof vinyl sheet. A layer of glass fleece or paper is placed on top of the molten PVC. A melamine layer can be applied to the top under elevated temperature and pressure.

[0009] WO2020 / 194202A1 describes a board comprising a substrate and a top layer. The top layer comprises at least melamine resin and an adhesive. The adhesive is selected from the group consisting of: polyacrylate adhesives, polyvinyl acetate adhesives, polyester adhesives, acrylic copolymer adhesives, or polyurethane adhesives.

[0010] DE102019203755A1 describes a method for producing a board. The method includes the following steps: (A) coating a carrier web with a liquid polymerizable coating; (B) drying the coated carrier web (with the polymerizable coating uncrosslinked or only partially crosslinked); (C) producing a multilayer structure comprising at least one coated carrier web and at least one core layer; and pressing the multilayer structure to fully crosslink the polymerizable coating. Optionally, an adhesive layer is added between the carrier web and the substrate, in which case the adhesive layer may be made of paper impregnated with a thermosetting resin. A disadvantage of this method is that the adhesion between the layers is not always optimal.

[0011] EP3587108A1 describes a board made of wood. This board comprises a core layer made of particleboard and an outer layer of wood fibers or a laminate layer. A paper impregnated with a synthetic resin is disposed between the core layer and the outer layer. An adhesive layer, for example, may be a hot-melt adhesive, a polyurethane adhesive, or an ethylene-vinyl acetate adhesive, is disposed between the resin-impregnated paper and the outer layer. Summary of the Invention

[0012] The object of this invention is to provide a board with excellent adhesion between the layers in the board. Furthermore, at least some embodiments of the invention aim to optimize board production by using polyurethane as an adhesive layer.

[0013] When laminating the layers, the condensation moisture formed during the crosslinking of the melamine-formaldehyde resin can cause problems related to the adhesion of the layers. In all aspects of the present invention, polyurethane is used to ensure improved adhesion between the layers of the produced board. The various aspects of the present invention address the aforementioned problems, thereby improving the adhesion between the layers.

[0014] A first aspect of the invention relates to a sheet comprising a paper layer, characterized in that the paper layer is impregnated with polyurethane, wherein the polyurethane can be crosslinked at elevated temperatures.

[0015] This sheet can be used as an adhesive layer in a board in other aspects of the invention. The paper layer in the sheet provides a carrier for the polyurethane in the sheet.

[0016] A preferred embodiment of the first aspect of the invention is characterized by the fact that the polyurethane-free paper layer has a dry weight of 10 g / m² to 50 g / m², for example, 25 g / m². This embodiment ensures the acquisition of a sheet with optimal performance. The paper effectively acts as a carrier, while being sufficiently open to allow the sheet to bond to both sides of the sheet during the lamination process, and there is no risk of sheet separation after the sheet has been used as an adhesive layer during lamination.

[0017] A preferred embodiment of the first aspect of the invention is characterized by the fact that the paper layer is an α-cellulose paper having an ash content of less than 5% by weight. This embodiment ensures the acquisition of a sheet with optimal performance. The paper effectively acts as a carrier, while being sufficiently open to allow the sheet to bond to both sides of the sheet during the lamination process, and there is no risk of sheet separation after the sheet has been used as an adhesive layer during lamination.

[0018] A preferred embodiment of the first aspect of the invention is characterized by the fact that the paper layer is impregnated with polyurethane having a dry weight of 20 g / m² to 60 g / m². This embodiment provides good results and excellent adhesion when using sheets in the lamination process.

[0019] A preferred embodiment of the first aspect of the invention is characterized by the fact that polyurethane is applied to the paper sheet via a water-based dispersion.

[0020] A preferred embodiment of the first aspect of the invention is characterized by the fact that polyurethane is anionicly stable. This embodiment provides good stability of the sheet, allowing the sheet to be stored for a period of time before being used in the lamination process.

[0021] A preferred embodiment of the first aspect of the invention is characterized by the fact that the polyurethane is self-crosslinking.

[0022] A preferred embodiment of the first aspect of the invention is characterized by the fact that the minimum film-forming temperature (MFFT) of the polyurethane is from 0°C to 50°C, preferably from 8°C to 35°C. This embodiment ensures good processability of the sheet during the lamination process.

[0023] A preferred embodiment of the first aspect of the invention is characterized by the fact that the polyurethane is at least partially carboxyl-stabilized. This embodiment provides good stability of the polyurethane dispersion used.

[0024] A preferred embodiment of the first aspect of the invention is characterized by the fact that, after complete curing, the polyurethane has a curing time of 50 to 150 seconds according to ISO 1522:2006. Hardness. It has been found that these sheets achieve good performance when used as adhesive layers during lamination.

[0025] A preferred embodiment of the first aspect of the invention is characterized by the fact that the polyurethane contains a crosslinking agent, such as one or more of isocyanate, carbodiimide, aziridine, or melamine. When such a sheet is used as an adhesive layer during the lamination process, it is advantageous if the resulting laminated product exhibits improved water resistance.

[0026] A preferred embodiment of the first aspect of the invention is characterized by the fact that the polyurethane contains silane. Using this sheet during the lamination process yields a laminate with improved hydrophobicity.

[0027] A preferred embodiment of the first aspect of the invention is characterized by the fact that the paper layer is saturated with polyurethane. This leads to optimization of the lamination process using sheets and optimization of the properties of the laminate, for example, through optimal adhesion of the sheets.

[0028] A second aspect of the invention relates to a board comprising a substrate and a top layer containing a decorative paper layer, wherein the decorative paper layer is impregnated with melamine-formaldehyde resin, characterized in that the top layer is bonded to the substrate by a sheet as described in any embodiment of the first aspect of the invention, by crosslinking the sheet with polyurethane. The decorative paper layer may have a uniform color or may have a decorative printed pattern.

[0029] In certain lamination processes where the top layer must be laminated onto the substrate, the condensation moisture of the melamine-formaldehyde resin in the decorative top layer can have negative consequences during the lamination process; for example, if this condensation moisture cannot be absorbed or drained, bubbles will form. During the production of the board according to the second aspect of the invention, this problem does not occur because the sheet provides adhesion between the top layer and the substrate.

[0030] An example of a board according to a second aspect of the invention is a board in which the substrate is or comprises a dense board, wherein a top layer is laminated on a pre-produced dense board. The use of sheets in the first aspect of the invention prevents the problem of condensation moisture caused by the condensation reaction of the melamine-formaldehyde resin in the decorative paper. A dense board is a board comprising a plurality of paper sheets impregnated with phenolic resin, which are compressed under pressure and elevated temperature to form a board.

[0031] A preferred embodiment of the second aspect of the invention is characterized by the fact that the board includes a backing layer on the side opposite to the side comprising the top layer, wherein the backing layer is or contains a paper layer impregnated with melamine-formaldehyde resin, the paper layer being bonded to the substrate by a sheet as in any embodiment of the first aspect of the invention, wherein the crosslinking of the polyurethane in the sheet provides adhesion between the backing layer and the substrate. Again, adhesion problems between the backing layer and the substrate due to condensation moisture from the melamine-formaldehyde resin in the backing layer are prevented.

[0032] A preferred embodiment of the second aspect of the invention is characterized by the fact that, on the side facing the substrate, the top layer of the board comprises a paper layer impregnated with resin. Preferably, the resin-impregnated paper layer is impregnated with phenolic resin.

[0033] According to a second aspect of the invention, the board can have an embossed design on its decorative surface by using a textured pressing surface during the lamination process. Using this resin-impregnated paper layer allows for a deeper embossing into the decorative surface of the board. This paper layer also better handles the problem of condensation moisture from the cross-linked melamine-formaldehyde resin, resulting in further improved adhesion between the layers.

[0034] A preferred embodiment of the second aspect of the invention is characterized by the fact that the resin-impregnated paper layer is in direct contact with the decorative paper layer.

[0035] A preferred embodiment of the second aspect of the present invention is characterized by the fact that the substrate comprises at least one of the following or is composed of at least one of the following:

[0036] (i) Dense board, which is a board made of paper sheets pressed together at elevated temperatures and impregnated with phenolic resin. The term phenolic resin also includes resins containing other components besides phenol and formaldehyde, such as melamine;

[0037] (ii) Mineral boards, such as gypsum board or magnesium oxide board;

[0038] (iii) Vinyl sheets containing fillers—such as mineral fillers or wood-based fillers, or

[0039] (iv) Boards comprising wood fibers or wood chips bonded together by thermosetting adhesives such as urea-formaldehyde resin or diphenylmethane diisocyanate resin, or by thermoplastic adhesives such as thermoplastic PVB (polyvinyl butyral) and / or by elastomeric adhesives such as elastomeric PVB (polyvinyl butyral).

[0040] (v) Polyurethane board or polyisocyanurate board.

[0041] A preferred embodiment of the second aspect of the invention is characterized by the fact that the top layer includes an abrasion-resistant layer on top of the decorative paper layer, wherein the abrasion-resistant layer comprises a paper layer impregnated with melamine-formaldehyde resin, the paper layer optionally comprising particles that increase abrasion resistance, such as alumina particles.

[0042] Here, the use of adhesive sheets is even more important because the lamination process also releases condensation water during the crosslinking of the melamine-formaldehyde resin in the wear-resistant layer.

[0043] A preferred embodiment of the second aspect of the invention is characterized by the fact that, on the side facing the top layer, the substrate includes an additional layer, wherein the additional layer is bonded to the substrate by, for example, a sheet as in any embodiment of the first aspect of the invention. An example of such an additional layer is aluminum foil that makes the board flame-retardant.

[0044] The use of sheet material again provides good adhesion between the layers in the board.

[0045] A preferred embodiment of the second aspect of the invention is characterized by the fact that the decorative surface of the panel includes an embossed design, preferably wherein the embossed design is pressed onto the decorative surface. This embossed design can be pressed onto the surface of the panel during a pressing operation under pressure and elevated temperature, wherein the top layer is laminated onto the substrate via a sheet layer. During this process, the polyurethane in the sheet crosslinks, and the melamine-formaldehyde resin (if present) of the decorative layer and the abrasion layer also crosslinks. When a textured pressure element is used in this pressing operation, the embossed design is pressed onto the surface of the panel.

[0046] A third aspect of the invention relates to a board comprising a substrate and a top layer (including a decorative paper layer impregnated with melamine-formaldehyde resin), characterized in that the top layer is bonded to the substrate by a polyurethane adhesive layer; preferably, the polyurethane adhesive layer does not contain a carrier or reinforcing layer. The decorative paper layer may have a uniform color or may have a decorative printed pattern.

[0047] In certain lamination processes where the top layer must be laminated onto the substrate, the condensation moisture of the melamine-formaldehyde resin in the decorative top layer can have negative consequences during the lamination process; for example, if this condensation moisture is not absorbed or cannot be drained, bubbles will form. This problem does not occur during the production of the panels according to the third aspect of the invention because polyurethane provides adhesion between the top layer and the substrate.

[0048] An example of a board according to a third aspect of the invention is a board in which the substrate is or comprises a dense board, wherein a top layer is laminated on a pre-produced dense board. The use of polyurethane as an adhesive layer prevents the problem of condensation moisture generated during the condensation reaction of the melamine-formaldehyde resin in the decorative paper.

[0049] A preferred embodiment of the third aspect of the invention is characterized by the fact that, on the side facing the substrate, the top layer of the board comprises a paper layer impregnated with resin. Preferably, the paper layer impregnated with resin is impregnated with phenolic resin.

[0050] Preferably, the resin-impregnated paper layer is in direct contact with the decorative paper layer.

[0051] According to a third aspect of the invention, the board can have an embossed design on its decorative surface by using a textured pressing surface during the lamination process. Using this resin-impregnated paper layer allows for a deeper embossing onto the decorative surface of the board. This paper layer also better addresses the issue of condensation moisture involved in the crosslinking of melamine-formaldehyde resin, resulting in further improved adhesion between the layers.

[0052] A preferred embodiment of the third aspect of the invention is characterized by the fact that, on the side opposite to the side containing the top layer, the board includes a backing layer, wherein the backing layer is or contains a paper layer impregnated with melamine-formaldehyde resin, wherein the backing layer is bonded to the substrate by a polyurethane adhesive layer; preferably, wherein the polyurethane adhesive layer does not contain a carrier or reinforcing layer. Again, this prevents adhesion problems between the backing layer and the substrate due to the condensation of moisture in the melamine-formaldehyde resin of the backing layer.

[0053] A preferred embodiment of the third aspect of the present invention is characterized by the fact that the substrate comprises at least one of the following:

[0054] (i) Dense board, which is a board made of paper sheets pressed together at elevated temperatures and impregnated with phenolic resin. The term phenolic resin also includes resins containing other components besides phenol and formaldehyde, such as melamine.

[0055] (ii) Mineral boards, such as gypsum board or magnesium oxide board.

[0056] (iii) Vinyl sheets containing fillers—such as mineral fillers or wood-based fillers, or

[0057] (iv) Boards comprising wood fibers or wood chips bonded together by thermosetting adhesives—such as urea-formaldehyde resin or diphenylmethane diisocyanate resin—or by thermoplastic adhesives—such as thermoplastic PVB (polyvinyl butyral)—and / or by elastomeric adhesives—such as elastomeric PVB (polyvinyl butyral).

[0058] (v) Polyurethane board or polyisocyanurate board.

[0059] A preferred embodiment of the third aspect of the invention is characterized by the fact that the top layer includes an abrasion-resistant layer on top of the decorative paper layer, wherein the abrasion-resistant layer comprises a paper layer impregnated with melamine-formaldehyde resin, the paper layer optionally including particles, such as alumina particles, to increase abrasion resistance.

[0060] Here, the use of a polyurethane adhesive layer is even more important because the lamination process also releases condensation water during the crosslinking of the melamine-formaldehyde resin in the wear-resistant layer.

[0061] A preferred embodiment of the third aspect of the invention is characterized by the fact that, on the side facing the top layer, the substrate contains an additional layer, wherein the additional layer is bonded to the substrate by a polyurethane adhesive layer; preferably, the polyurethane adhesive layer does not contain a carrier or reinforcing layer. An example of such an additional layer is aluminum foil that makes the board flame-retardant.

[0062] The use of a polyurethane adhesive layer further ensures good adhesion between the layers in the board.

[0063] A preferred embodiment of the third aspect of the invention is characterized by the fact that the decorative surface of the panel includes an embossed design, preferably wherein the embossed design is pressed onto the decorative surface. This embossed design can be pressed onto the surface of the panel during a pressing operation under pressure and elevated temperature, wherein the top layer is laminated onto the substrate via a polyurethane adhesive layer. During this process, the polyurethane in the polyurethane adhesive layer crosslinks, and crosslinking also occurs in the melamine-formaldehyde resin of the decorative layer and the abrasion layer (if the latter is present). When a textured pressure element is used in this pressing operation, the embossed design is pressed onto the surface of the panel.

[0064] The fourth aspect of the invention relates to a method for producing a plate, for example, in any embodiment of the second aspect of the invention, wherein the method comprises the following steps:

[0065] -Provide base materials,

[0066] - Provides a top layer containing a decorative paper layer impregnated with melamine-formaldehyde resin;

[0067] - Provide a sheet, for example, as in any embodiment of the first aspect of the invention, and arrange the sheet between a substrate and a top layer;

[0068] - The top layer, sheet, and substrate are pressed together under elevated temperature and pressure, during which melamine-formaldehyde resin crosslinks, and the crosslinking of the polyurethane in the sheet provides adhesion between the top layer and the substrate.

[0069] The decorative paper layer can have a uniform color, or it can have a decorative printed pattern.

[0070] This method produces high-quality boards in which the layers have been bonded to each other in a satisfactory manner.

[0071] A preferred embodiment of the fourth aspect of the invention is characterized by the fact that the temperature during pressing is 140 to 220 degrees Celsius, more preferably 160 to 220 degrees Celsius, and even more preferably 180 to 220 degrees Celsius. These conditions produce optimal results during pressing.

[0072] A preferred embodiment of the fourth aspect of the invention is characterized by the fact that the duration of the pressing operation is 10 to 120 seconds, preferably 10 to 60 seconds, and even more preferably 12 to 22 seconds. These conditions produce optimal results during the pressing process.

[0073] The fifth aspect of the invention relates to a method for producing a plate as described in any embodiment of the third aspect of the invention, wherein the method comprises the following steps:

[0074] -Provide base materials,

[0075] - Provides a decorative paper layer impregnated with melamine-formaldehyde resin;

[0076] - A resin-impregnated paper layer, preferably impregnated with phenolic resin, is provided between the substrate and the decorative paper layer; wherein the side of the paper layer facing the substrate contains a polyurethane coating.

[0077] - Under elevated temperature and pressure, the substrate, resin-impregnated paper layer, and decorative paper layer are pressed together, during which cross-linking of melamine-formaldehyde resin and cross-linking of polyurethane coating occur, causing the substrate, resin-impregnated paper layer, and decorative paper layer to be laminated together.

[0078] The decorative paper layer can have a uniform color, or it can have a decorative printed pattern.

[0079] This method produces high-quality boards in which the layers have been bonded to each other in a satisfactory manner.

[0080] A preferred embodiment of the fifth aspect of the invention is characterized by the fact that the temperature during pressing is 140 to 220 degrees Celsius, more preferably 160 to 220 degrees Celsius, and even more preferably 180 to 220 degrees Celsius. These conditions produce optimal results during pressing.

[0081] A preferred embodiment of the fifth aspect of the invention is characterized by the fact that the duration of the pressing operation is 10 to 120 seconds, preferably 10 to 60 seconds, and even more preferably 12 to 22 seconds. These conditions produce optimal results during the pressing process.

[0082] A sixth aspect of the invention relates to a board, wherein the board includes a substrate and a top layer bonded to the substrate, wherein the top layer contains decorative paper, wherein the decorative paper is impregnated with melamine-formaldehyde resin or impregnated with acrylate resin, wherein on the side bonded to the substrate, the decorative paper includes a polyurethane adhesive layer that provides adhesion between the decorative paper and the substrate.

[0083] The layers in the board are bonded to each other satisfactorily. There is no risk of local or complete delamination. The problem of condensation moisture that can occur during the crosslinking of melamine-formaldehyde resin is prevented. An example of this problem is the appearance of bubbles. Polyurethane provides good adhesion between the top layer and the substrate, while the resin impregnating the decorative paper ensures that the decorative paper layers are prevented from separating. It has been found that decorative paper impregnated with polyurethane alone (which must provide the required adhesion) is insufficient to prevent paper separation. Therefore, decorative paper impregnated with both resin—melamine-formaldehyde resin or acrylic resin—and a polyurethane adhesive layer is required to produce high-quality boards. Polyurethane can be applied by coating onto decorative paper impregnated with melamine-formaldehyde resin or acrylic resin, after which the top layer can be pressed onto the substrate under increased pressure and temperature, during which crosslinking of the resin and polyurethane occurs.

[0084] A preferred embodiment of the sixth aspect of the invention is characterized by the fact that the polyurethane adhesive layer contains 7 to 15 grams of polyurethane by dry weight. These embodiments produce excellent results in terms of board quality.

[0085] A preferred embodiment of the sixth aspect of the invention is characterized by the fact that decorative paper is bonded to a substrate layer containing polyvinyl butyral as both an adhesive and a filler via a polyurethane adhesive layer. The filler may be a wood-based filler, such as sawdust and / or wood fibers and / or wood dust. More preferably, the substrate further includes a layer made of MDF (medium-density fiberboard) or HDF (high-density fiberboard). Examples of such a substrate include MDF or HDF boards on which a layer comprising a wood-based filler bonded together by thermoplastic or elastomer polyvinyl butyral (PVB) is arranged.

[0086] Due to their melamine-formaldehyde resin composition, melamine-formaldehyde impregnated decorative layers adhere well to MDF or HDF boards. However, they have been found to adhere poorly to layers containing wood-based fillers and have been bonded to each other using thermoplastic or elastomer polyvinyl butyral (PVB). In contrast, the use of a polyurethane adhesive layer, as in this embodiment of the invention, ensures good adhesion and high-quality boards.

[0087] A preferred embodiment of the sixth aspect of the invention is characterized by the fact that polyurethane is anionicly stable. These embodiments provide good stability of the sheet, allowing the sheet to be stored for a period of time before being used in the lamination process.

[0088] The preferred embodiment of the sixth aspect of the present invention is characterized by the fact that the polyurethane is self-crosslinking.

[0089] A preferred embodiment of the sixth aspect of the invention is characterized by the fact that the minimum film-forming temperature (MFFT) of the polyurethane is 5°C to 50°C, preferably 8°C to 35°C. This embodiment provides good processability during the pressing operation, wherein a board is produced by laminating the layers together.

[0090] A preferred embodiment of the sixth aspect of the invention is characterized by the fact that, after complete curing, the polyurethane has a curing time of 50 to 150 seconds according to ISO 1522:2006. Hardness. It has been found that using this polyurethane produces good properties for use as an adhesive layer in this invention.

[0091] The preferred embodiment of the sixth aspect of the present invention is characterized by the fact that the polyurethane is at least partially carboxyl-stabilized.

[0092] A preferred embodiment of the sixth aspect of the invention is characterized by the fact that the substrate comprises wood fibers and / or wood chips, preferably wherein the wood fibers and / or wood chips are bonded together by a thermosetting adhesive or by a thermoplastic plastic.

[0093] A preferred embodiment of the sixth aspect of the invention is characterized by the fact that the decorative surface of the plate includes an embossed design, preferably wherein the embossed design is pressed onto the decorative surface.

[0094] This embossing can be pressed onto the surface of the board during a pressing operation under pressure and elevated temperature, with the top layer laminated onto the substrate via a polyurethane adhesive layer.

[0095] The seventh aspect of the invention relates to a board, optionally a board as in any embodiment of the sixth aspect of the invention, wherein the board comprises a substrate and a top layer bonded to the substrate, wherein the top layer comprises decorative paper impregnated with melamine-formaldehyde resin or impregnated with acrylic resin, wherein on the side opposite to the side bonded to the substrate, the top layer comprises a lacquer layer, wherein the lacquer layer optionally contains particles to increase abrasion resistance, characterized in that the board comprises a polyurethane adhesive layer providing adhesion between the decorative paper and the lacquer layer.

[0096] The polyurethane adhesive layer provides good adhesion between the lacquer layer and the impregnated decorative paper. When using adhesives via polyurethane, decorative paper impregnated with melamine-formaldehyde resin or acrylic resin may seem redundant. However, it has been found that while polyurethane does provide adhesion to the lacquer layer without such impregnation, there is a risk of the decorative paper separating. The inventors suspect this is due to insufficient saturation of the decorative paper with polyurethane, even if polyurethane has been applied to the decorative paper or the paper has been immersed in a bath. Therefore, the decorative paper is first impregnated with resin—melamine-formaldehyde resin or acrylic resin—before the polyurethane adhesive layer is applied.

[0097] Examples of paint layers that can be used in this case are acrylic paint layers, polyurethane acrylic paint layers, polyurethane paint layers, or thermosetting polyester paint layers.

[0098] Preferably, the paint layer is directly bonded to the impregnated decorative paper using a polyurethane adhesive layer.

[0099] A preferred embodiment of the seventh aspect of the invention is characterized by the fact that the polyurethane adhesive layer providing bonding between the decorative paper and the lacquer layer contains 7 to 15 grams of polyurethane by dry weight. This embodiment produces excellent results in terms of board quality.

[0100] The preferred embodiment of the seventh aspect of the invention is characterized by the fact that the polyurethane in the polyurethane adhesive layer that provides bonding between the decorative paper and the lacquer layer is anionicly stable.

[0101] A preferred embodiment of the seventh aspect of the invention is characterized by the fact that the polyurethane in the polyurethane adhesive layer that provides bonding between the decorative paper and the lacquer layer is self-crosslinking.

[0102] The preferred embodiment of the seventh aspect of the invention is characterized by the fact that the minimum film-forming temperature (MFFT) of the polyurethane providing the bonding between the decorative paper and the lacquer layer is 5°C to 50°C, preferably 8°C to 35°C.

[0103] A preferred embodiment of the seventh aspect of the invention is characterized by the fact that the polyurethane in the polyurethane adhesive layer that provides bonding between the decorative paper and the lacquer layer is at least partially carboxyl-stabilized.

[0104] A preferred embodiment of the seventh aspect of the invention is characterized by the fact that the substrate contains wood fibers and / or wood chips, preferably wherein the wood fibers and / or wood chips are bonded together by a thermosetting adhesive or by a thermoplastic plastic.

[0105] A preferred embodiment of the seventh aspect of the invention is characterized by the fact that the decorative surface of the plate includes an embossed design, preferably wherein the embossed design is pressed onto the decorative surface.

[0106] During the pressing operation in which the top layer is laminated onto the substrate via a polyurethane adhesive layer, this embossing can be pressed onto the surface of the board under pressure and elevated temperature.

[0107] The preferred embodiments of the sixth and / or seventh aspects of the invention, wherein the decorative paper is impregnated with melamine-formaldehyde resin, are characterized by the fact that the melamine-formaldehyde resin contains at least 25% by weight of a modifier relative to the total amount of melamine-formaldehyde resin. This weight percentage is determined relative to the amount of dry matter. An advantage of this embodiment is that it facilitates the production of high-quality boards because the decorative paper impregnated with this melamine-formaldehyde resin is more easily coated with polyurethane on one or both sides; the polyurethane then forms one or more adhesive layers. The inventors suspect that this is due to the fact that a higher amount of modifier results in a more flexible melamine-formaldehyde resin impregnated decorative paper.

[0108] More preferably, the melamine-formaldehyde resin contains at least 30% by weight of a modifier relative to the total amount of the melamine-formaldehyde resin. Even more preferably, the melamine-formaldehyde resin contains at least 35% by weight of a modifier relative to the total amount of the melamine-formaldehyde resin. Even more preferably, the melamine-formaldehyde resin contains at least 40% by weight of a modifier relative to the total amount of the melamine-formaldehyde resin. These weight percentages are determined relative to the amount of dry matter.

[0109] For example, modifiers that can be used in this case include glycerol, polyols, polyethylene glycol, polyvinyl alcohol, phenoxyethanol, phenylethylene glycol, sugars, dimethylformamide, caprolactam, guanidine, toluenesulfonamide, dicyandiamide, and urea. Attached Figure Description

[0110] To illustrate the features of the invention in more detail, some preferred embodiments are described below by way of example with reference to the accompanying drawings, but are not limited thereto, wherein:

[0111] Figure 1 A plate according to a second aspect of the invention is shown;

[0112] Figure 2 A plate according to a second aspect of the invention is shown;

[0113] Figure 3 A plate according to a third aspect of the invention is shown;

[0114] Figure 4 A plate according to a third aspect of the invention is shown; and

[0115] Figure 5 A plate according to the sixth and seventh aspects of the invention is shown. Detailed Implementation

[0116] Figure 1A plate (10) according to a second aspect of the invention is shown. The plate (10) includes a substrate (11) and a top layer (8). The top layer (8) includes a decorative paper layer (18) having a uniform color or printed with decorations. The decorative paper layer is impregnated with melamine-formaldehyde resin.

[0117] The top layer (8) includes an abrasion-resistant layer (19) located on top of the decorative paper layer (18). The abrasion-resistant layer is a paper layer impregnated with melamine-formaldehyde resin, which optionally includes particles to increase abrasion resistance, such as alumina particles.

[0118] On the side facing the substrate (11), the top layer (8) includes a paper layer (16) impregnated with resin, preferably a phenolic resin. In this example, the resin-impregnated paper layer (16) is in direct contact with the decorative paper layer (18).

[0119] The top layer (8) is bonded to the substrate by a sheet (14) as described in the first aspect of the invention. The sheet comprises a paper layer impregnated with polyurethane, wherein the top layer (8) of the board is bonded to the substrate by the polyurethane of the cross-linked sheet.

[0120] exist Figure 1 In the example, the substrate (11) is a dense board, but for the present invention, the substrate is not necessarily or may include a dense board. A dense board is a board composed of paper sheets pressed together at elevated temperatures and impregnated with phenolic resin.

[0121] On the side opposite to the side including the top layer (8), the board (10) includes a backing layer (13). The backing layer (13) is a melamine-formaldehyde resin impregnated paper layer that is bonded to the substrate (11) by a sheet (14) as described in the first aspect of the invention, wherein the polyurethane crosslinking of the sheet provides adhesion between the backing layer and the substrate. The sheet (14) includes a polyurethane-impregnated paper layer.

[0122] Optionally, the decorative surface of the board may contain embossing, for example, due to the use of textured pressure elements under pressure and elevated temperature during the pressing operation. During this pressing operation, the aforementioned layers are pressed together, resulting in crosslinking of the individual resins and polyurethanes.

[0123] Figure 2 A plate (10) according to a second aspect of the invention is shown. The plate (10) includes a substrate (11) and a top layer (8). The top layer (8) includes a decorative paper layer (18) having a uniform color or printed with decorations. The decorative paper layer is impregnated with melamine-formaldehyde resin.

[0124] The top layer (8) includes an abrasion-resistant layer (19) located on top of the decorative paper layer (18). The abrasion-resistant layer is a paper layer impregnated with melamine-formaldehyde resin, which optionally includes particles to increase abrasion resistance, such as alumina particles.

[0125] Although Figure 2 The example is not shown, but the top layer facing the substrate may also include a paper layer impregnated with resin, preferably a phenolic resin; the resin-impregnated paper layer may be in direct contact with the decorative paper layer.

[0126] The top layer (8) is bonded to the substrate by a sheet (14) as described in the first aspect of the invention. The sheet (14) comprises a paper layer impregnated with polyurethane, wherein the top layer (8) of the board is bonded to the substrate by the polyurethane of the cross-linked sheet.

[0127] exist Figure 2 In the example, the substrate (11) includes a dense board (17), but for the present invention, the substrate does not necessarily include a dense board. A dense board is a board composed of paper sheets pressed together at elevated temperatures and impregnated with phenolic resin.

[0128] On the side facing the top layer (8), the substrate (11) includes an additional layer, in Figure 2 In one example, the additional layer is an aluminum foil (22). The aluminum foil (22) is bonded to the substrate by a sheet (14) as described in the first aspect of the invention. The sheet (14) comprises a paper layer impregnated with polyurethane, wherein the top layer (8) of the sheet is bonded to the substrate by the polyurethane of the cross-linked sheet.

[0129] On the side opposite to the side including the top layer (8), the board (10) includes a backing layer (13). The backing layer (13) is a paper layer impregnated with melamine-formaldehyde resin, which is bonded to the substrate (11) by a sheet (14) as described in the first aspect of the invention, wherein the polyurethane crosslinking of the sheet provides adhesion between the backing layer and the substrate. The sheet (14) includes a paper layer impregnated with polyurethane.

[0130] Optionally, the decorative surface of the board may contain embossing, for example, due to the use of textured pressure elements under pressure and elevated temperature during the pressing operation. During this pressing operation, the aforementioned layers are pressed together, resulting in crosslinking of the individual resins and polyurethanes.

[0131] Figure 3 A plate (10) according to a third aspect of the invention is shown. The plate (10) includes a substrate (11) and a top layer (8). The top layer (8) includes a decorative paper layer (18) having a uniform color or printed with decorations. The decorative paper layer is impregnated with melamine-formaldehyde resin.

[0132] The top layer (8) includes an abrasion-resistant layer (19) located on top of the decorative paper layer (18). The abrasion-resistant layer is a paper layer impregnated with melamine-formaldehyde resin, which optionally includes particles to increase abrasion resistance, such as alumina particles.

[0133] On the side facing the substrate (11), the top layer (8) includes a paper layer (16) impregnated with resin, preferably a phenolic resin. In this example, the resin-impregnated paper layer (16) is in direct contact with the decorative paper layer (18).

[0134] The top layer (8) is bonded to the substrate via a polyurethane adhesive layer (30). The polyurethane adhesive layer (30) does not contain a carrier or reinforcing layer.

[0135] The polyurethane adhesive layer (30) can be produced by coating a phenolic resin impregnated paper layer (16) with a polyurethane dispersion. Then, during the pressing process, the layers—including the layers of the top layer (8)—are laminated together under pressure and temperature.

[0136] exist Figure 3 In the example, the substrate (11) is a dense board, but for the present invention, the substrate is not necessarily or includes a dense board. A dense board is a board composed of paper sheets pressed together at elevated temperatures and impregnated with phenolic resin.

[0137] On the side opposite to the side including the top layer (8), the board (10) includes a backing layer (13). The backing layer (13) is a melamine-formaldehyde resin impregnated paper layer that is bonded to the substrate (11) by a polyurethane adhesive layer (31). This can be achieved by coating the melamine-formaldehyde resin impregnated paper layer that forms the backing layer with a polyurethane dispersion. During the pressing operation in which the board is produced, the polyurethane crosslinks, thereby creating a bond between the backing layer (13) and the substrate (11).

[0138] Optionally, the decorative surface of the board may include embossing, for example, due to the use of textured pressure elements under pressure and elevated temperature during the pressing operation. During the pressing operation, the aforementioned layers are pressed together, resulting in crosslinking of the individual resins and polyurethanes.

[0139] Figure 4 A plate (10) according to a third aspect of the invention is shown. The plate (10) includes a substrate (11) and a top layer (8). The top layer (8) includes a decorative paper layer (18) having a uniform color or printed with decorations. The decorative paper layer is impregnated with melamine-formaldehyde resin.

[0140] On top of the decorative paper layer (18), the top layer (8) includes an abrasion-resistant layer (19). The abrasion-resistant layer is a paper layer impregnated with melamine-formaldehyde resin, which optionally includes particles to increase abrasion resistance, such as alumina particles.

[0141] The top layer (8) is bonded to the substrate via a polyurethane adhesive layer (30). The polyurethane adhesive layer (30) does not contain a carrier or reinforcing layer.

[0142] exist Figure 4In the example, the substrate (11) includes a dense board (17), but for the present invention, the substrate does not necessarily include a dense board. A dense board is a board composed of paper sheets pressed together at elevated temperatures and impregnated with phenolic resin.

[0143] On the side facing the top layer (8), the substrate (11) includes an additional layer, in Figure 4 In this example, the additional layer is an aluminum foil (22). The aluminum foil (22) is bonded to the substrate by a polyurethane adhesive layer (32). This can be achieved by coating the aluminum foil (22) with a polyurethane dispersion. The top layer (8) is bonded to the substrate by a polyurethane adhesive layer (30), which can also be achieved by coating the other side of the aluminum foil (22) with a polyurethane dispersion.

[0144] During the pressing operation, the layers are bonded together under pressure and elevated temperature using cross-linked resin and polyurethane.

[0145] On the side opposite to the side including the top layer (8), the board (10) includes a backing layer (13). The backing layer (13) is a melamine-formaldehyde resin impregnated paper layer that is bonded to the substrate (11) by a polyurethane adhesive layer (31). This can be achieved by coating the melamine-formaldehyde resin impregnated paper layer that forms the backing layer with a polyurethane dispersion. During the pressing operation in which the board is produced, the polyurethane crosslinks, thereby creating a bond between the backing layer (13) and the substrate (11).

[0146] Optionally, the decorative surface of the board may include embossing, for example, due to the use of textured pressure elements under pressure and elevated temperature during the pressing operation. During the pressing operation, the aforementioned layers are pressed together, resulting in crosslinking of the individual resins and polyurethanes.

[0147] Figure 5 A plate (10) according to the sixth and seventh aspects of the invention is shown. These two aspects are not necessarily combined in the invention.

[0148] Figure 5 The board (10) includes a substrate (11) and a top layer (8) bonded to the substrate (11). The top layer (8) includes decorative paper (18) impregnated with melamine-formaldehyde resin or impregnated with acrylic resin. On the side bonded to the substrate (11), the decorative paper (18) includes a polyurethane adhesive layer (53) that provides adhesion between the decorative paper and the substrate. Preferably, the polyurethane adhesive layer (53) contains 7 g / m² to 15 g / m² of polyurethane by dry weight.

[0149] Figure 5The substrate (11) in the example includes a first layer (51) and a second layer (52). In this example, the first layer is MDF (medium-density fiberboard) or HDF (high-density fiberboard). The second layer (52) is a layer comprising polyvinyl butyral (as a binder) and wood-based fillers (e.g., wood chips and / or wood fibers).

[0150] The polyurethane adhesive layer (53) provides adhesion between the decorative paper layer (18) and the second layer (52) of the substrate (11).

[0151] On the opposite side of the side bonded to the substrate (11), the top layer (8) includes a lacquer layer (55). This can be an acrylic lacquer layer, a polyurethane acrylic lacquer layer, a polyurethane lacquer layer, or a thermosetting polyester lacquer layer. The lacquer layer (55) optionally includes particles to increase abrasion resistance. A polyurethane adhesive layer (54) provides adhesion between the decorative paper (18) and the lacquer layer (55). The polyurethane adhesive layer (54) preferably comprises polyurethane with a dry weight of 7 g / m² to 15 g / m².

[0152] Optionally, the board may include a backing layer (13), preferably a melamine-formaldehyde resin impregnated paper layer. The backing layer (13) may be bonded to the substrate by melamine-formaldehyde resin. Alternatively, the melamine-formaldehyde resin impregnated paper layer may be bonded to the substrate (11) by a polyurethane adhesive layer.

[0153] Optionally, the decorative surface of the board may include embossing, for example, due to the use of textured pressure elements under pressure and elevated temperature during the pressing operation. During the pressing operation, the aforementioned layers are pressed together, resulting in crosslinking of the individual resins and polyurethanes.

Claims

1. Panel, wherein the panel (10) comprises a substrate (11) and a top layer (8) comprising a decorative paper layer (18) having a uniform colour or printed with a decoration, wherein the decorative paper layer is impregnated with melamine formaldehyde resin, characterised in that, The top layer is bonded to the substrate by means of a sheet, wherein the sheet (14) includes a paper layer, wherein the paper layer is impregnated with polyurethane, wherein the polyurethane is capable of crosslinking at elevated temperatures; The top layer is bonded to the substrate by cross-linking the polyurethane of the sheet (14).

2. The panel of claim 1, wherein The paper layer, excluding the polyurethane, has a dry weight of 10 g / m² to 50 g / m².

3. The panel of claim 1, wherein The paper layer is α-cellulose paper with an ash content of less than 5% by weight.

4. The panel of claim 1, wherein The paper layer is impregnated with the polyurethane at a dry weight of 20 g / m² to 60 g / m².

5. The plate according to claim 1, characterized in that, The polyurethane is applied to paper sheets via a water-based dispersion.

6. The plate according to claim 1, characterized in that, The polyurethane is anionic stable.

7. The plate according to claim 1, characterized in that, The polyurethane is self-crosslinking.

8. The plate according to claim 1, characterized in that, The minimum film-forming temperature (MFFT) of the polyurethane is 0°C to 50°C.

9. The plate according to claim 1, characterized in that, The polyurethane is at least partially carboxyl-stabilized.

10. The plate according to claim 1, characterized in that, After complete curing, the polyurethane has a König hardness of 50 to 150 seconds according to ISO 1522:2006.

11. The plate according to claim 1, characterized in that, The polyurethane contains a crosslinking agent provided by one or more of isocyanates, carbodiimides, aziridines, or melamine.

12. The plate according to claim 1, characterized in that, The polyurethane contains silane.

13. The plate according to claim 1, characterized in that, The paper layer is saturated with the polyurethane.

14. The plate according to claim 1, characterized in that, On the side opposite to the side including the top layer (8), the board (10) includes a backing layer (13), wherein the backing layer is a melamine-formaldehyde resin impregnated paper layer or a melamine-formaldehyde resin impregnated paper layer, the paper layer being bonded to the substrate by means of a sheet. The sheet includes a paper layer, the paper layer is impregnated with polyurethane, the polyurethane is crosslinkable at elevated temperatures, and the crosslinking of the polyurethane in the sheet provides adhesion between the backing layer and the substrate.

15. The plate according to claim 14, characterized in that, On the side facing the substrate, the top layer (8) of the board includes a paper layer (16) impregnated with resin.

16. The plate according to claim 15, characterized in that, The resin-impregnated paper layer (16) is in direct contact with the decorative paper layer (18).

17. The plate according to claim 1, characterized in that, The substrate includes at least one of the following: (i) a dense board, said dense board being composed of paper sheets pressed together at elevated temperatures and impregnated with phenolic resin. (ii) Mineral plates, (iii) Vinyl veneer containing filler, (iv) A board comprising wood fibers or wood chips, said wood fibers or wood chips being bonded together by means of a thermosetting adhesive, or by means of a thermoplastic adhesive, or by means of an elastomer adhesive. (v) Polyurethane board or polyisocyanurate board.

18. The plate according to claim 1, characterized in that, The top layer (8) includes an abrasion-resistant layer (19) on top of the decorative paper layer, wherein the abrasion-resistant layer comprises a paper layer impregnated with melamine-formaldehyde resin, and the paper layer optionally includes particles to increase abrasion resistance.

19. The plate according to claim 1, characterized in that, On the side facing the top layer (8), the substrate (11) includes an additional layer. The additional layer is bonded to the substrate by means of a sheet; wherein the sheet comprises a paper layer, wherein the paper layer is impregnated with polyurethane, wherein the polyurethane is capable of crosslinking at elevated temperatures.

20. The plate according to claim 1, characterized in that, The decorative surface of the panel includes embossing.

21. A method for producing the plate of claim 1, wherein the method comprises the following steps: - Provide base materials, - A top layer containing a decorative paper layer impregnated with melamine-formaldehyde resin is provided; - Provide a sheet; and arrange the sheet between the substrate and the top layer, wherein the sheet (14) includes a paper layer, wherein the paper layer is impregnated with polyurethane, wherein the polyurethane is capable of crosslinking at elevated temperatures; - The top layer, the sheet, and the substrate are pressed together under elevated temperature and pressure, during which melamine-formaldehyde resin crosslinks, and the crosslinking of the polyurethane in the sheet provides adhesion between the top layer and the substrate.

22. The method according to claim 21, characterized in that, The temperature during pressing is between 140 and 220 degrees Celsius.

23. The method according to claim 21, characterized in that, The duration of the pressing operation is from 10 seconds to 120 seconds.

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