Plate-shaped material and methods for its manufacture.

Abstract

The invention relates to a plate-shaped material containing lignocellulosic fibers and binders. To achieve a plate-shaped material with reduced swelling using fibers, the amount of binder must exceed 50% of the weight of the plate-shaped material. The invention also includes a method for manufacturing the plate-shaped material.

Description

[0001] The invention relates to a plate-shaped material and a method for its production as well as the use of the plate-shaped material.

[0002] Sheet-like materials made from lignocellulosic fibers are used in a wide variety of applications because their production is inexpensive and technically mature. A typical example is the use of high-density fiberboard (HDF), in which wood fibers are pressed into boards using binders and then usually coated with resin-impregnated paper. This coating hardens under pressure and temperature, forming a firmly bonded laminate. This laminate is cut into pieces, and the edges are profiled, for example, to be used as glueless flooring. However, the material is exposed at the profiled edges. In the presence of water, the wood fibers at these exposed edges begin to swell due to water absorption, leading to a change in the shape of the wood-based panel. This water can be either free-flowing water or even high humidity. High humidity, for example, caused by...Swelling, which can be caused by seasonal factors or technical reasons, may preclude the use of laminate flooring, even though it is largely reversible, meaning that drying can mostly reverse the swelling. However, swelling cannot be completely reversed, so that an unsightly open joint remains after initial swelling.

[0003] Alternatives to laminate flooring include wood-plastic composites (WPC), an extruded mixture of wood fibers and plastic, described, for example, in DE 10 2007 041 438 A1, US 5,985,429 A, CN 109249491 A1, and US 2004 / 0235983 A1. With a sufficiently high plastic content, WPC is dimensionally stable under the influence of water or moisture. However, its production requires the use of...

[0004] Extruders that are not suitable for the production of sheet-shaped materials of larger dimensions.

[0005] Finally, materials are available from which non-swelling, sheet-like materials can be produced that contain no wood fibers or other wood components. This eliminates the need for a renewable, abundant raw material with good strength properties. Examples of such raw materials include stone plastic composites (SPC) and polyvinyl chloride (PVC). These materials typically contain halogens or terephthalates, making them environmentally unsound. The sheet-like material according to the invention is low-emission or emission-free; in particular, formaldehyde emissions can be largely reduced or avoided, thus complying with California's CARB 2 formaldehyde emission regulations. Volatile organic compounds (VOCs) can also be largely or completely avoided.

[0006] Furthermore, WO 2011 / 107900 A1 describes a reduced-swelling, plate-shaped material containing binders as well as fibers and expanded particles. The manufacturing process is complex and the material comprises numerous components.

[0007] The object of the invention is to provide a plate-shaped material and a method for its production which exhibits reduced swelling when using fibers.

[0008] This problem is solved by a method according to claim 1 and a plate-shaped wood-based material 10. The use of the plate-shaped material according to the invention is covered in claim 19.

[0009] The invention relates to a sheet-shaped material comprising fibers and a binder, characterized in that the proportion of the binder, based on the sheet-shaped material, is more than 50% by weight. Fibers within the meaning of this invention are elongated solid particles, i.e., particles whose diameter is many times smaller than their longest dimension. The dimensions of the fibers can be selected within a wide range; they depend in particular on the sheet thickness and on the requirements for the homogeneity of the sheet-shaped material. The diameter of the fibers ranges from 10 µm to 5 mm, and the length of the fibers from 0.05 mm to 100 mm. The sheet-shaped material thus has a larger proportion of binder than fibers. The binder content can also be expressed in terms of fibers, that is, the proportion of binder is specified with reference to the weight of the fibers used.For hygroscopic fibers that can absorb moisture (e.g., lignocellulosic fibers), the fiber content is specified as fibers dried to constant weight, usually at 105 °C (dry fibers: absolutely dry fibers). The binder content of the sheet-like material is then, based on the fiber content, more than 100 wt.%.

[0010] Organic or inorganic fibers can be used for the sheet-like material according to the invention. Natural fibers, e.g., lignocellulosic fibers, cotton or linen fibers, or synthetic fibers such as fibers made of thermoplastic material like polyethylene or polypropylene, but also of polycarbonate, polyacrylate, polymethacrylate, or polyurethane, can be used to produce the material according to the invention. Inorganic fibers such as carbon fibers or fibers made of mineral or ceramic raw materials or glass fibers are particularly suitable for producing the sheet-like material when mixed with other fibers. In particular, mixtures of fibers, especially mixtures of the aforementioned fibers, can be used to produce the material according to the invention. Mixtures of fibers make it possible to adjust the properties of the material according to the invention, e.g.,The elasticity or bending properties, dimensional stability, strength, but also the manufacturing properties or processability are important. If fibers from renewable raw materials, especially lignocellulosic fibers, e.g., fibers from wood, bamboo, or annual plants, are used, inexpensive, easy-to-process fibers are available. Natural fibers are preferably used untreated, i.e., the fiber components cellulose and lignin, and possibly hemicelluloses, are not altered in their properties by chemical processes. The use of hygroscopic fibers is not excluded, especially if they are at least partially dried before the production or pressing of the material according to the invention.

[0011] The lignocellulosic fibers mentioned above include, in particular, all fibers obtained from plants through chemical or physical processes. Typical examples of physically obtained fibers are softwood fibers, hardwood fibers, or bamboo fibers, or fibers from other organic raw materials obtained through mechanical fiber degradation. Examples of chemically obtained fibers include cellulose fibers from wood, annual plants, or other raw materials, especially renewable resources. Wood fibers from mechanical fiber degradation are particularly common, with the aim of minimizing the loss of lignin and hemicelluloses. Fiber blends can also be used, especially to adjust the material properties (strength, weight) and to optimize the cost-effective use of fiber as a raw material.Fibers within the meaning of this invention also include fiber bundles; smaller chips are also included, provided that their fibers can still be largely coated with binder.

[0012] The material according to the invention is plate-shaped, i.e., it generally has two main surfaces, which are hereinafter also referred to as the top and bottom surfaces. The narrow surfaces or edges of the material are arranged between the top and bottom surfaces. The thickness of the finished plate-shaped material can range from 0.8 mm to 500 mm, typically between 1 mm and 80 mm, and usually between 3 mm and 30 mm. A typical application may require a thickness of the plate-shaped material of 4 mm to 10 mm, particularly between 4 mm and 7 mm. The material according to the invention can have flat main surfaces, but the top and / or bottom surfaces can also be embossed, milled, or otherwise machined, resulting in a variable thickness of the material relative to its surface area. The material preferably has a substantially homogeneous composition throughout its thickness.The edges, whose height corresponds to the thickness of the material, can be machined with conventional tools. They can be sawn, cut, or milled. The maximum length and width of the sheet-like material according to the invention are limited only by the available presses used to manufacture the material. Smaller dimensions can be produced by dividing the sheet-like material into sections. Typical dimensions of the sheet-like material can be 5600 mm (length) x 2070 mm (width) after production in the press, 1380 mm x 195 mm after dividing into floor, wall, or ceiling panels, or 3048 mm x 2800 mm. The latter format is particularly well-suited for use in construction because the width of the panel corresponds to the floor height.

[0013] The sheet-shaped material according to the invention can be used in a variety of ways. It can be used, for example, as flooring, ceiling and / or wall coverings, for the manufacture of interior fittings or furniture, particularly for the interior fittings of vehicles such as vehicle cabins, but also outdoors, both as cladding, e.g., as a curtain wall, and for structural applications. The sheet-shaped material according to the invention can be coated, colored, painted, or otherwise decoratively finished. In particular, surface coatings, such as those known from the field of wood-based materials, can be applied to the surface of the material according to the invention. Furthermore, the sheet-shaped material according to the invention can be used as a component of a sandwich panel, i.e.,h, that the material according to the invention is combined with the same or other foil- or plate-shaped materials, in particular wood-based panels, but also plastic panels or films to form a sandwich panel.

[0014] The material according to the invention differs from the WPC described above in that it does not consist of plastic, in particular thermoplastic plastic with fibers, formed into a sheet-like material, but rather a binder is used that forms a cohesive and / or adhesive interaction with the fibers. Such binders are known, for example, from the prior art of wood-based panel production. The binder used according to the invention preferably comprises melamine. Melamine is used in aqueous solution as melamine resin, wherein the solids content of the melamine is preferably at least 45% by weight based on the aqueous solution, and advantageously the solids content is over 50% by weight. The upper limit of the solids content is determined by the solubility and, if applicable, the processability of the melamine, e.g., in spray nozzles.Melamine is preferred as a binder because it is non-swelling, non-hygroscopic, and resistant to hydrolysis. Melamine can be used as a binder either alone or in combination with one or more other binders. In the context of this invention, "in combination" means that mixtures of binders can be used, wherein either the mixture of two or more binders is applied to the fiber simultaneously, e.g., as MF resin (melamine-formaldehyde resin). Or a combination of binders is used that are applied sequentially, e.g., because they cannot be used in mixture or because separate application of different binders has an advantageous effect. In combination with the aforementioned melamine, or alternatively, other binders such as, for example,Formaldehyde, methylenediphenyl diisocyanate (MDI), also in emulsified form as eMDI or polymeric diphenylmethane diisocyanate (PMDI), and polyurethane can also be used. Phenolic resin is water-resistant but dark-colored, which is a disadvantage in application. As described above, two or more binders can also be used in combination. It is preferred if the binder predominantly comprises melamine. It is further preferred if the proportion of melamine in the binder exceeds 20 wt.%, and in particular 50 wt.%. The binder is preferably urea-free, since urea contributes to hygroscopicity and thus to the swelling of the lignocellulosic fibers, or does not prevent it. Thermoplastic binders are advantageously avoided. The sheet-shaped material according to the invention is preferably free of halogens (e.g., fluorine, chlorine) and also of terephthalates.

[0015] According to the invention, the sheet-shaped material is modified, and in particular improved, in its elastic properties by the addition of an elastomer or thermoplastic, which is used as an elasticizing additive, e.g., by the addition of polyvinyl acetate (PVAc) or ethyl vinyl acetate. Acrylate, styrene acrylate, or polyurethane (PU) are preferably used for elasticizing the sheet-shaped material according to the invention, particularly in the form of a liquid additive such as a dispersion, because they are water-resistant. Acrylate, styrene acrylate, and PU with a glass transition temperature (TG) below 0 °C are preferred. However, mono- or diethylene glycol are also suitable for elasticizing the sheet-shaped material. The aforementioned elasticizing additives can each be used individually or in mixtures.The addition of elastomers or thermoplastics reduces the brittleness of the sheet material and improves the elastic properties of the sheet material according to the invention, e.g., the modulus of elasticity. Furthermore, the addition of elasticizing additives results in better flatness of the sheet material. The elasticizing additive is used as a solid, calculated proportionally to the amount of solid material in the synthetic resin used. The elasticizing additive is used in a ratio of 1:1, preferably 0.7:1, particularly 0.2:1, and advantageously 0.01:1, relative to the synthetic resin. The elasticizing additive is therefore not used as the main component of the binder, especially not as the main component by quantity. The elasticizing additives are added, for example, to the binder, e.g., melamine resin, before application to the fibers and applied to the fibers together with the binder.Alternatively, the elasticizing agent can be applied to the fibers before or after the binder.

[0016] The binder, supplemented by the elasticizing additive, constitutes the largest proportion of the sheet-like material according to the invention, usually the predominant proportion. Preferably, the sheet-like material has more than 100 wt.%, e.g., 101 wt.% or 102 wt.% up to 120 wt.% binder, based on the fiber content; advantageously, the material has more than 150 wt.% binder, particularly preferably more than 200 wt.% binder, and a maximum of 500 wt.% binder, in each case based on the fiber content.

[0017] The density of the material according to the invention is between 1,000 kg / m³ and 1,800 kg / m³, in particular between 1,000 kg / m³ and 1,600 kg / m³, advantageously between 1,000 kg / m³ and 1,300 kg / m³, and particularly advantageously between 1,030 kg / m³ and 1,200 kg / m³. Due to the high binder content, the material according to the invention has a higher density compared to, for example, a wood-based material such as an HDF board, which consists predominantly of lignocellulosic fibers, e.g., between 1,000 kg / m³ and 1,200 kg / m³.

[0018] The material preferably contains fillers. Fillers can be added to optimize, usually minimize, the weight of the sheet-like material or to further improve the matrix structure of binder and fibers. Alternatively or additionally, an additive or a combination of additives can serve to optimize certain properties of the sheets, such as conductivity, insulating properties, or strength properties. In the material according to the invention, an additive replaces fibers. Since the material should exhibit minimal swelling, particularly minimal thickness swelling, in the presence of water, non-hygroscopic or non-swelling additives, as well as additives resistant to hydrolysis, are preferred. Such additives can be mineral particles, but also ceramic, synthetic, or glass particles.Calcium carbonate (CaCO3) and / or barite (BaSO4) can also be used as additives. The particle size is preferably no larger than one millimeter, preferably between 10 µm and 800 µm. Mixtures of different particles can also be used, e.g., mixtures of different materials or sizes. Up to 30 wt.% based on the total weight of the sheet-like material is used, particularly preferably up to 20 wt.%, advantageously up to 15 wt.%. The lower limit of the amount used is determined by the detectability of an additive. The additive can be applied to the fibers before or after the binder is applied, preferably by spraying.

[0019] According to an advantageous embodiment of the invention, the sheet-shaped material incorporates hydrophobic agents, e.g., paraffin or wax, which are typically used in amounts of up to 5 wt.% based on the weight of the sheet-shaped material, usually in amounts of up to 2 wt.%, and often in amounts of 0.1 wt.% to 1 wt.%. The use of hydrophobic agents also contributes to a reduction in the swelling tendency of the sheet-shaped material.

[0020] The invention further relates to a method for producing a sheet-shaped material comprising fibers and binders, wherein the proportion of the binder in the sheet-shaped material is more than 50 wt.%, comprising the steps: Providing fibers, providing the binder, preferably in liquid form, applying the binder to the fibers, forming a fiber cake, pressing the fiber cake in a press while the binder hardens to produce a sheet-shaped material.

[0021] The steps of the process correspond to those of a conventional process, e.g., for manufacturing a wood-based panel in a press. However, according to the invention, a larger quantity of binder is used than previously known, so that the weight fraction of the binder is greater than the weight fraction of the fibers.

[0022] When synthetic or inorganic fibers are used, it may be necessary to at least partially dry the binder on the fibers. If the fibers contain moisture, as is common with lignocellulosic fibers, the moisture content should be adjusted before pressing the fiber cake so that a dimensionally stable, non-swelling, and non-shrinking board is obtained after pressing. Lignocellulosic fibers are often used with a moisture content of up to 120 wt.% or more before sizing. The lignocellulosic fibers can be dried before or after the application of the binder. During pressing, it is preferred that the lignocellulosic fibers have a moisture content of at least 3 wt.% to a maximum of 15 wt.%, that is, a water content of at least 3 wt.% to 15 wt.% based on the total weight of the fibers.

[0023] The binder is typically supplied in liquid form. It can be supplied in pure form or—more commonly—in solution, either in solvent or water, or as a dispersion or emulsion. The binder is usually applied to the lignocellulosic fibers by spraying, for example, using multiple spray nozzles that create a spray mist of the binder and are arranged around a downward flow of fibers. A typical example of such a drying device is a blowline, which is used in fiberboard production. The surface of the fibers is wetted with binder droplets or a binder mist. After optional drying, the binder-wetted fibers are formed into a fiber cake and pressed. During this process, the binder hardens, resulting in a sheet-like material.During curing, which occurs under the influence of pressure and temperature primarily on the top and bottom surfaces of the fiber cake, irreversible chemical bonds are formed between the fibers and the binder, as well as within the binder itself, unlike in WPC products. The process according to the invention avoids the effort of kneading and extrusion.

[0024] Surprisingly, it has been found that the pressing conditions are essentially the same as those of known wood-based materials, particularly those with a reduced proportion of binder compared to the invention. Pressure, temperature, and pressing time are, for example, comparable to those of conventional HDF (high-density fiberboard) panels. The material according to the invention can be excellently produced in presses such as those used for the manufacture of wood-based materials. In particular, continuous or discontinuous hot presses are suitable, e.g., continuous double-belt presses with circulating, heated metal belts or intermittent presses. This allows for the production of panel formats that—unlike with WPC—are not limited to the production of narrow plank formats with a width of approximately 30 cm. Rather, conventional panel formats, such as those commonly used for wood-based panels, can be produced.

[0025] The production of the fiber cake, as is common with wood-based materials, is generally carried out by spreading. The fibers, either freshly coated with the entire quantity of binder or preferably dried, are spread onto a carrier, usually a conveyor belt, typically in a homogeneous layer, but alternatively also in several layers, the layers of which can have different compositions with regard to fibers, binder, or additives. The spread fiber cake on the carrier is, if necessary, first passed through a pre-press and then compressed in a press. The press acts on both the top and bottom surfaces of the fiber cake or the sheet-shaped material.

[0026] Any press that applies sufficient pressure and temperature is suitable, including both a plate press, in which the material is pressed between two sheets, and especially a continuous press, in which the material is pressed between two circulating metal belts. Hot presses are preferred, in which the press plates or circulating metal belts are heated to a predetermined temperature. Suitable pressing temperatures can be selected from 140 °C to 220 °C, preferably from 160 °C to 180 °C. The thinner the sheet, the lower the pressing temperature can be. Suitable pressing pressures are, for example, in the range of 0.3 N / mm² to 5.5 N / mm², particularly 1 N / mm² to 3 N / mm². The pressing time is advantageously 6 seconds / mm of sheet thickness (hereinafter: s / mm) to 60 s / mm, usually 10 s / mm to 20 s / mm.In continuous presses, the feed rate of the circulating metal belts, between which the sheet-like material is produced by pressing, is usually between 350 mm / second and 400 mm / second.

[0027] A pre-press for compacting the fiber cake can be installed prior to the actual pressing process. Optionally, a device for cooling the sheet-shaped material can be installed downstream of the press, in particular a device for cooling under a predetermined pressing pressure, which may be lower than the pressing pressure during pressing the material.

[0028] The additives, wet-strength agents or hydrophobizing agents described above can be added to the material according to the invention, typically before or during the forming of the fiber cake.

[0029] The material produced according to the inventive process preferably has a surface that essentially comprises binder and the elasticizing additive, and particularly preferably a surface consisting of either binder or the elasticizing additive. Especially when using hygroscopic fibers, e.g., lignocellulosic fibers, the aim is to have as few fibers as possible on the surface of the material in order to optimize thickness swelling as much as possible. Water in liquid form or, for example, as atmospheric humidity would be absorbed by the hygroscopic fibers, resulting in swelling of the material. This is undesirable. The high or predominant proportion of binder in the sheet-like material enables a surface of the material that predominantly or completely comprises binder and an elasticizing additive, or that has hardly any or no hygroscopic fibers.

[0030] The material according to the invention can be processed like a wood-based panel, e.g., an HDF panel. The surface can be coated, embossed, or milled; the edges can be profiled, e.g., for the production of floor panels. The sheet-like material according to the invention can be laminated with resin-impregnated papers, printed, varnished, stained, or otherwise processed. It is considered an advantage of this invention that the sheet-like material can be processed and manufactured using existing equipment.

[0031] The disclosure further includes a device for producing the aforementioned sheet-shaped material, comprising means for coating lignocellulosic fibers with a binder, which, according to the invention, includes means for coating pre-coated lignocellulosic fibers. The term "coating" here refers to the application of a binder. The means for coating fibers are advantageously designed as nozzles that generate a spray of liquid binder. Fibers are guided through the binder spray, onto which binder droplets from the spray are then deposited. Known means for coating lignocellulosic fibers are designed to apply a maximum of 30% by weight of binder based on the fibers to be coated.The process according to the invention can be carried out by repeatedly passing the fibers to be sized through the known sizing agents until sufficient binder has been applied to the fibers. However, it is proposed to arrange several of the known sizing agents such that the fibers to be sized are conveyed along a plurality of sizing agents, each agent applying a portion of the binder to the lignocellulosic fibers until the desired total amount of at least more than 50 wt.% of the sheet-like material has been applied to the fibers. Thus, in addition to the known agents for sizing unsized fibers (fibers without binder), further agents for sizing pre-sized fibers, to which a portion of the binder has already been applied, are used.

[0032] The sheet-shaped material according to the invention can be adapted to various requirements by different combinations of fibers, binders, fillers and optionally other additives such as waxes. It is therefore expressly pointed out that the features described above can be freely combined with one another.

[0033] The invention further relates to the use of the aforementioned sheet-shaped material. A key characteristic of the sheet-shaped material according to the invention is its versatility due to minimal swelling, particularly the almost completely reduced thickness swelling in the edge area. In interior construction, the sheet-shaped material can be used, for example, as flooring panels or laminate flooring. Unlike, for example, HDF floor panels, its use is also possible in damp and wet rooms because the edge profile, where the core of the panel is freely exposed to moisture, no longer swells significantly under the influence of water or high humidity, nor does it shrink during drying. Thickness swelling of less than 3%, preferably less than 2%, relative to the original panel thickness, is considered insignificant within the meaning of the invention.The plate-shaped materials according to the invention, optimized for minimal thickness swelling, exhibit thickness swelling according to DIN 317 or edge swelling according to DIN 13329 of only 0.5% to 1%. The plate-shaped material according to the invention is therefore low-swelling or, when a maximum thickness swelling of up to 1% relative to the original plate thickness is achieved, swelling-free and dimensionally stable. Thus, for example, a plate-shaped, essentially non-swelling material that is dimensionally stable against water or atmospheric humidity can now be produced on known devices for manufacturing wood-based panels. This material is not limited to narrow formats and preferably maximizes the use of renewable raw materials.

[0034] Naturally, the sheet-like material according to the invention can also be used as a wall or ceiling panel, as a furniture panel, particularly in the construction of damp and wet rooms or laboratories, technical rooms, and workshops, but this is not limited to these applications. In exterior construction, the material according to the invention is suitable as a facade panel or for roofing. The sheet-like material according to the invention can be used, for example, for terrace construction, including decking boards or exterior flooring. In this way, it becomes possible to use the same flooring or floor coverings for interior and adjacent exterior areas (terraces, balconies, facades, walkways). The sheet-like material according to the invention is preferably used for structures, especially furniture, in exterior areas. The construction of workshops, production halls, or stables, for example, can easily be carried out using the material according to the invention.The sheet-like material can optionally be designed as a panel and, if required, provided with a profile along the edges. The profile preferably serves to fix two panels together. Alternatively, two adjacent panels can also be butted together using double-sided adhesive tape applied laterally to a joint between the directly adjoining panels. Bonding directly adjacent panels or sheets is also possible, preferably using a waterproof adhesive.

[0035] The plate-shaped material according to the invention exhibits good strength properties, in particular a high transverse tensile strength of at least 2.5 N / mm², preferably up to 3 N / mm², and particularly up to 4 N / mm². The material according to the invention also exhibits high compressive strength. The good strength properties mean that fewer fasteners, e.g., screws, are required to fasten a plate made of the material according to the invention, because each individual fastener has a better hold in the plate. The higher transverse tensile strength also allows for more intensive machining of a plate made of the material according to the invention, e.g., the milling of complex profiles into the side edge of a plate. For example, a complex profile can be machined into the side edge of a plate only 4.3 mm thick, aligning two interlocking plates with each other in both the vertical and horizontal directions.The high compressive strength allows the sheet material to withstand high point loads, making it suitable, for example, for vehicle loading floors or as flooring for storage areas. The high flexural stiffness of the sheet material allows its use as a structural element, e.g., for wall stiffening.

[0036] Details of the invention are explained below using exemplary embodiments. It shows: Fig. 1 a schematic representation of a plate-shaped material according to the invention

[0037] The figure shows a sheet-shaped material 1 with a top surface 2, a bottom surface 3, and an edge 4. The material contains fibers 5 embedded in a binder. The binder constitutes more than 50% by weight of the sheet-shaped material. Thus, more binder than fiber 5 is used. Natural, synthetic, organic, and inorganic fibers can be used, either individually or in mixtures. Hygroscopic fibers such as wood, cellulose, or linen fibers can also be used. Melamine is the preferred binder, often in combination with formaldehyde or phenol, but also in mixtures with PMDI. Examples of fiber-binder combinations are described below. Example 1

[0038] For the experiment, the results of which are shown in Table 1 below, lignocellulosic fibers, in this case softwood fibers, were used. The fibers were produced from steamed wood chips by fiberization in a refiner. Alternatively, any other lignocellulosic fibers or mixtures of such fibers can be used. The softwood fibers are used at a moisture content of 120% before sizing; before pressing, they are dried with the binder present on them to a residual moisture content of 8%, i.e., one ton of fibers contains 80 kg of water.

[0039] For this experiment, more than 100 wt%, in this case 108 wt%, of binder based on oven-dry wood is used, specifically a binder comprising melamine-formaldehyde resin (MF resin). The melamine-formaldehyde resin (MF resin) used in the binder had a solids concentration of 60% (measured at 60 min / 120°C). Thus, 180 grams of liquid binder, containing 108 g of MF resin, were applied to 100 grams of oven-dry fiber (oven-dry wood), taking into account the liquid content (108 g at 60% solids concentration = 180 g). "Oven-dry wood" here refers to lignocellulosic fibers that have been dried at 105°C until constant weight is achieved. "Oven-dry wood" is a common reference measure for formulations containing lignocellulosic fibers. The subsequent embodiments refer to the absolute amount of binder used.

[0040] Furthermore, 1.2 wt% paraffin based on dry wood is used.

[0041] The binder is applied to the lignocellulosic fibers in four passes, with 27% by weight applied to each fiber in each pass. The liquid binder is sprayed through nozzles in a known fiber sizing device. The spray mist generated by the nozzles settles on the surface of the fibers as they pass through it, for example, by falling from top to bottom through the binder spray.

[0042] The fiber gluing process is followed by drying of the glued fibers in drying equipment, such as a hot air tunnel or shaft that applies heated air to the fibers. The aim of drying is not to completely remove all liquid, but to dry the binder to the point where it is no longer sticky. The drying process should not impair the binder's reactivity during curing under pressure and / or temperature.

[0043] After drying, the fibers can be stored or further sizing / processed. First, a second pass through the sizing device follows, in which another 27 wt% MF resin is sprayed onto the fibers, which have already been pre-sized after the first pass. After the second pass, the sized fibers are dried until they no longer adhere to each other. A third and fourth pass through the sizing device and drying agent are carried out in the same manner. Alternatively, the 110 wt% binder can be applied to the fibers in one or two passes, or alternatively in five or more passes. The amount of binder applied to the fibers in each pass can vary from pass to pass.

[0044] After each pass, a portion of the sizing fibers is removed and processed into a sheet-like material with a thickness of 7 mm. This is done by spreading a fiber cake, which is then pressed in a known continuous double-belt press at 180 °C and a pressure of 2.5 N / mm² for a pressing time of 15 s / mm. The resulting sheet has a thickness of 5.5 mm and a density of 1050 kg / m³. As a reference, a sheet-like material produced under the same conditions without an increased binder addition is tested (Table 1, pass o).

[0045] The resulting sheet-shaped material is tested for swelling according to DIN 317 and for edge swelling according to DIN 13329. Thickness swelling is determined at an edge of the material as a change in mm relative to the initial thickness of 7 mm, both as an absolute change and as a relative change (%). Table 1 Thickness swelling for a sheet-shaped material, thickness 7 mm, binder content increasing from 0 to 108 wt.% Passage No. 0 1 2 3 4 Absolute difference (mm) 1,47 0,50 0,25 0,21 0,12 Relative difference (%) 22,92 7,45 3,82 3,05 1,83

[0046] For the sheet-like material without added binder (pass 0), the thickness swelling, as expected according to Table 1, is approximately 23% at its maximum. Each pass, in which 27 wt% MF resin is applied, reduces the thickness swelling at the edge of the sheet-like material. An exceptionally low edge swelling value of 1.83% is achieved when 108 wt% binder, based on the dry wood content, is used. Example 2

[0047] For the fiber component of the sheet-shaped material in embodiment 2, a 50:50 mixture of different fibers is used, for example, wood fibers and carbon fibers, alternatively, for example, recycled paper fibers and glass wool fibers, or alternatively, mineral fibers and cellulose fibers. The natural fibers (wood, recycled paper, cellulose fibers) are preferably dried before gluing. The fibers can be mixed before or after gluing and the optional drying of the binder. Both variants allow the production of a homogeneous mixture of glued fibers, which can then be spread into a fiber cake. Otherwise, embodiment 2 is identical to embodiment 1 with regard to the use of the binder and the use of paraffin. Example 3

[0048] Exemplary embodiment 3 relates to a mixture of fibers and binder, in which 50 parts polyethylene fibers, 20 parts carbon fibers, and 10 parts aggregate, e.g., glass particles, mineral or ceramic particles, constitute the fiber portion, which is smeared with 115 wt.% binder, here, for example, with MF resin. The fiber-aggregate-binder mixture is otherwise treated as in exemplary embodiment 1. Example 4

[0049] The aim is to produce a fiber and binder panel suitable for use in flooring, specifically one that can be coated with a decorative surface, either with resin-impregnated paper or by varnishing. The panel will contain 40% by weight of fibers with a density of approximately 550 kg / m³ and 55% by weight of a binder, in this case a MF resin with a melamine content exceeding 60%. Additionally, 5% by weight of other substances will be used, specifically 1.5% by weight of paraffin and 3.5% by weight of a gray dye. The dye is used to give the panel a uniform color.

[0050] The sheet-shaped material with the aforementioned composition is produced on an industrial, continuous press and compared with HDF boards made from the same fiber material, but with a binder content of 15 wt.%, and which have a density of 880 kg / m 3<. Table 2 Comparative tests on the swelling of an HDF and a board according to the invention Attempt Panel thickness (mm) Binder (%) Density (kg / m³< ) Transverse tensile strength (N / mm²< ) Swelling of raw plate (%) Edge swelling coated (%) Standard HDF 6 15% 880 >1,4 18 - 22 14 - 18 sheet-shaped material 5,8 137,5% 1050 >4,5 0,1-,03 1,0 - 1,2

[0051] Table 2 above compares the two plates, specifying the plate thickness in mm as a gross value (before grinding) and the density in kg / m³. The plates were evaluated according to transverse tensile strength (DIN EN 319), swelling (measured according to EN 317) and edge swelling (measured according to EN 13329).

[0052] Due to its high fiber content, the board according to the invention can be compressed more effectively than a fiberboard. The amount of binder used is approximately nine times higher than in a prior art HDF board. The board-shaped material according to the invention exhibits three times the transverse tensile strength and a 100-fold reduction in the swelling of the raw board. After laminating the top and bottom surfaces, the edge swelling is measured with the board "coated." Only the edges remain exposed to water, as the top and bottom surfaces of the board are sealed by the lamination process and are no longer accessible to water. This test is particularly important for floor coverings because the edges of floor panels generally cannot be sealed and are therefore exposed to water. Here, the edge swelling of the board material according to the invention is reduced to one-tenth compared to a known HDF board.Both the HDF board and the plate-shaped material according to the invention were produced on the same industrial production facilities.

Claims

1. A method for producing a planar material, comprising lignocellulosic fibers (5) and a binding agent, wherein the proportion of the binding agent with a used elasticizing additive is more than 50 wt% of the planar material (1), wherein the elasticizing additive is not used as the main component of the binder, having the steps of: providing lignocellulosic fibers (5), providing the binding agent, preferably in liquid form, wherein the binding agent comprises melamine-formaldehyde resin, phenolic resin, methylene diphenyl isocyanate (MDI), also in emulsified form as eMDI, polymeric diphenylmethane diisocyanate (PMDI), polyurethane, or mixtures of the aforementioned binding agents, as well as a liquid elasticizing additive, applying the binding agent with the elasticizing additive to the fibers (5), forming a fiber cake from the fibers provided with binding agent and the elasticizing additive, pressing the fiber cake in a press while curing the binding agent to create a planar material (1) with a density of 1,000 kg / m3 to 1,800 kg / m3.

2. Method according to claim 1, characterized in that acrylate, styrene acrylate, polyurethane, polyvinyl acetate, ethylene vinyl acetate, mono- or diethylene glycol are added as the elasticizing additive of the planar material.

3. Method according to claim 2, characterized in that the elasticizing additive is used as a solid in a ratio of maximally 1:1, preferably 0.7:1, in particular 0.2:1, advantageously at least 0.01:1 in relation to the solid of the binding agent.

4. Method according to claim 2 or 3, characterized in that the elasticizing additive is applied to the fibers before or after the binding agent or is mixed with the binding agent before being applied to the fibers and is then applied to the fibers.

5. Method according to one of the preceding claims, characterized in that a continuous or a discontinuous press, in particular a hot press, is used for producing the planar material.

6. Method according to one of the preceding claims, characterized in that the pressing temperature is 140 °C to 220 °C, preferably 160 °C to 180 °C.

7. Method according to one of the preceding claims, characterized in that the pressing pressure is 0.3 N / mm2 to 5.5 N / mm2, preferably 1 N / mm2 to 3 N / mm2.

8. Method according to one of the preceding claims, characterized in that the pressing duration is 6 seconds / mm of board thickness to 60 seconds / mm of board thickness, preferably 10 seconds / mm of board thickness to 20 seconds / mm of board thickness.

9. Method according to one of the preceding claims, characterized in that the fibers are provided wet, partially dried or dry with binding agent and optionally with the agent for elasticizing, wherein, when applying the binding agent and optionally the agent for elasticizing, the fibers are preferably subsequently dried.

10. A planar material, produced according to the method according to one of claims 1 to 9 in a press, comprising lignocellulosic fibers (5) and the binding agent, wherein the binding agent comprises melamine-formaldehyde resin, phenolic resin, methylenediphenyl diisocyanate (MDI), also in emulsified form as eMDI, polymeric diphenylmethane diisocyanate (PMDI), polyurethane, or mixtures of the aforementioned binding agents and wherein the proportion of the binding agent with an used elasticizing additive is more than 50 wt% of the planar material (1), which has a density of 1,000 kg / m3 to 1,800 kg / m3.

11. Material according to claim 10, characterized in that the material (1) comprises natural fibers, synthetic fibers, inorganic or organic fibers, or mixtures of fibers.

12. Material according to claim 11, characterized in that the organic, natural fibers comprise lignocellulose fibers from renewable raw materials, in particular coniferous wood fibers, deciduous wood fibers, fibers from annual plants, or bamboo fibers.

13. Material according to claim 11, characterized in that the synthetic fibers comprise fibers made of thermoplastic material, in particular fibers made of polyethylene or polypropylene, but also made of polycarbonate, polyacrylic, polymethacrylic, or polyurethane.

14. Material according to claim 11, characterized in that the inorganic fibers comprise fibers made of mineral, ceramic, or glass materials.

15. Material according to one of the preceding claims 10 to 14, characterized in that the proportion of binding agent in relation to atro wood is more than 101 wt%, more than 120 wt%, more than 150 wt% or more than 200 wt%.

16. Material according to one of the preceding claims 10 to 15, characterized in that the planar material (1) has an aggregate, in particular non-hygroscopic or non-swelling fillers.

17. Material according to claim 16, characterized in that mineral, ceramic, synthetic, or glass particles are used as the aggregate.

18. Material according to one of the preceding claims 10 to 17, characterized in that the planar material (1) has hydrophobing agents, for example paraffin or wax.

19. A use of a planar material according to at least one of claims 10 to 18, characterized in that the planar material (1) is used in interior finishing, in particular as a floor board or floor laminate, as a wall or ceiling board, as a furniture board, when finishing damp and wet rooms, in outdoor construction as a facade board or for roofing, for stables, for terrace construction, including decking or outdoor flooring, and outdoor structures, in particular outdoor furniture.