RU2781987C2 - Fiberboard and method for formation of fiberboard - Google Patents

Abstract

FIELD: building materials.

SUBSTANCE: group of inventions relates to the production of fiberboards. A fiberboard contains lignocellulose fibers and a binding agent pressed together. Lignocellulose fibers are mixed with the binding agent, while at least 95% by wt. of lignocellulose fibers with a moisture content of 6% pass through a woven sieve of metal wire with a cell width of 3 mm. At least 50% by wt. of lignocellulose fibers pass through the woven sieve of metal wire with a width cell of 630 mcm. The mixture of lignocellulose fibers and the binding agent is applied to a surface as at least the first layer. At least the first layer of the mixture of lignocellulose fibers and the binding agent is pressed to form fiberboard (16) having the total thickness from 0.5 to 7 mm and density of at least 930 kg/m³.

EFFECT: efficiency of fiberboard production is increased.

24 cl, 4 tbl, 2 dwg

Description

Technical field

The present invention relates to a fiberboard containing compressed lignocellulosic fibers and a binder. In addition, the present invention relates to a method for producing fiberboard.

State of the art

Fibreboard is an engineered wood product that is made from lignocellulosic fibers, most commonly wood fibers. The wood fibers are usually pressed with a binder (eg urea resin) to form a fibreboard. Fibreboard, especially medium density fibreboard (MDF), is widely used in the furniture industry. Types of fibreboard in the art include medium density fibreboard (MDF) and high density fibreboard (HDF). Veneers are often glued to visible parts of furniture made from fiberboard to give them the appearance of ordinary wood. Fibreboard is made from fresh wood. In addition, fine particles are generally not used in the production of fibreboard, as they are known to degrade the properties of the resulting fibreboard. It is known that the recycling of fibreboards and especially HDF boards for the production of new fibreboards is a difficult task.

During the production of furniture, a large amount of waste wood material is generated. This waste is generated when boards and wood products are cut and processed into the desired shapes and sizes. Waste typically includes sawdust, most of which consists of small particles, shavings and larger woody materials. This material, which is a mixed material, both in terms of particle size and material type (it may contain various types of wood, as well as some plastics, adhesives, etc.), is now commonly burned in a kiln/boiler for receiving energy. Apart from being used as a filler in plastics, fine wood waste, such as sawdust, is not used in other furniture or construction applications.

KR 20000002694 describes a polyolefin wood substitute containing shredded furniture waste as filler. A similar extruded polypropylene board containing shredded wood waste as a filler is described in KR 20010016955. As is known in the art, the use of wood fibers as fillers in plastics has been known for a long time. However, for most construction and furniture applications, a wood substitute with such a high proportion of plastic components is disadvantageous and cannot be used to replace conventional MDF boards or HDF boards. Plastic wood substitute cannot be processed in the same way as conventional MDF boards and HDF boards, and is difficult to recycle.

US 2010/0104813 describes an embossed fibreboard (MDF) having a density of about 700 kg/m ³ to about 900 kg/m ³ and a thickness of about 12.5 mm, which can be used, for example, as siding. The MDF consists of a single layer embossed MDF incorporating wood particles with an average size of less than 4mm. Raw materials are obtained from various sawmills or wood processing enterprises. The size of raw wood can be anything from logs to chips, shavings or sawdust. In embossed MDF, the particles are distributed in such a way that the smaller wood particles are mainly present on the surface of the board, while the larger particles are mainly present in the central part of the board. The only raw material used in US 2010/0104813 is 100% virgin wood, i. the raw material used to form the particles is untreated or recycled wood.

It would be interesting to be able to recycle lignocellulosic fibrous material in furniture production in a more efficient way. In particular, it would be of interest to recycle wood fiber boards such as MDF boards and HDF boards. In addition, it would be interesting to find a better way to use all the materials from wood waste from furniture production, including small lignocellulosic fibers, than to use them for energy.

Thus, there is a need for fibreboard made from recycled furniture, as well as from other waste generated during the production of furniture.

The essence of the invention

Accordingly, according to a first aspect of the invention, there is provided a fibreboard containing lignocellulosic fibers and a binder. Fibreboard is produced by mixing lignocellulosic fibers and a binder, placing the mixture as a layer on a surface, and pressing this layer to form a 0.5 to 7 mm thick fibreboard.

It has been found that the final properties of fibreboard depend on the density of the board. To ensure sufficient mechanical properties (eg modulus of elasticity) when using lignocellulosic fibers from recycled furniture, including small lignocellulosic fibers, it is necessary to press the material to a density of at least 930 kg/m ³ . Thus, the density of the proposed fibreboard should be at least 930 kg/m ³ .

In addition, it has been found that it is not necessary to discard fine lignocellulosic fibers, i.e., lignocellulosic fibers passing through a 630 µm woven metal wire screen, as is commonly done in the art, provided that the material is compressed to a density of at least 930 kg/m ³ . On the contrary, it has been found advantageous to include a relatively high proportion of fine lignocellulosic fibers. Fine lignocellulosic fibers should preferably be distributed throughout the board, and not just on the surface of the fibreboard, as they have been found to improve the structural integrity of the board. Small lignocellulosic fibers have a positive effect on the properties of the fibreboard. In addition, the use of previously discarded lignocellulosic fibers avoids the incineration of part of the lignocellulosic fibers resulting from the recycling of furniture, thereby improving the overall economics of the process. In the fiberboard of the present invention, at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers thus pass through a woven metal wire sieve with a mesh width of 630 µm; preferably through a 500 µm woven metal wire mesh. The moisture content of 6% is the moisture content of the dried material under laboratory standard climatic conditions (oven-dried (105°C) material immediately absorbs water from the atmosphere when it is taken out of the oven, so reaching zero (0%) content moisture in practical tests is almost impossible). At any given location on the fibreboard, the content of lignocellulosic fibers passing through a 630 µm woven metal wire mesh, preferably a 500 µm woven metal wire mesh, should preferably be at least 25% by weight, more preferably at least 40% of the mass.

In addition, the content of large lignocellulosic fibers must be low in order to provide the desired properties and to ensure efficient production of fibreboard. Thus, in the fiberboard of the present invention, at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm; preferably through a woven metal wire screen with a mesh width of 2 mm.

While the content of lignocellulosic fibers in the fiberboard is at least 50% of the mass. (at a moisture content of 6%) is acceptable, the content of lignocellulosic fibers in fibreboard is usually higher. According to one implementation variant, the content of lignocellulosic fibers in the fiberboard is at least 70, 80, 85, or 90% of the mass. (at a moisture content of 6%).

In one embodiment, the woven metal wire mesh and mesh width are in accordance with ISO 3310-1:2016 Test sieves - Specification and testing - Part 1: Metal wire cloth test sieves. In addition, screening with such a sieve can be performed in accordance with ISO 2591-1:1988 "Control screening - Part 1: Methods using test screens of woven wire and perforated metal plate". Further guidance is given in ISO 2395 Test sieves and test screening - Terminology and ISO 565:1990 Test sieves. Metal wire cloth, perforated metal plate and electroplated sheet. Nominal hole sizes. These additional standards are referenced in the aforementioned ISO 3310-1:2016.

As is known to a qualified specialist, the expression that at least X % of the mass. samples of lignocellulosic fibers pass through a woven metal wire sieve with a cell width of Y mm, which means that 100% -X% of the mass. samples are too large to pass through the specified sieve with a given mesh width, i.e. Y mm. For example, if 95% of the mass. of this sample pass through a woven metal wire sieve with a mesh width of 3 mm, then 5% of the mass. do not pass through it.

Preferably, not all lignocellulosic fibers in the fibreboard are fine fibres. Thus, lignocellulosic fibers in a fibreboard may meet one or more of the following criteria:

- at least 20, 25, 30 or 35% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a woven metal wire sieve with a mesh width of 125 microns; and/or

- at least 15, 20, 25 or 30% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a 315 µm woven metal wire mesh screen; and/or

- at least 5, 10, 15 or 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a woven metal wire sieve with a mesh width of 630 μm.

It is further preferred that some of the lignocellulosic fibers in the fiberboard are fine fibers or even very fine fibers. Thus, lignocellulosic fibers in a fibreboard may meet one or both of the following criteria:

- at least 5, 10, 15 or 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 125 microns; and/or

- at least 10, 15, 20, 25 or 30% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire screen with a mesh width of 315 microns.

Although the small amount of lignocellulosic fibers in the fiberboard may be very large fibers, it is preferred if the amount is limited. According to one implementation variant, at least 97.5% of the mass. (at a moisture content of 6%), for example, at least 99.0% of the mass. (at a moisture content of 6%) the lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm, more preferably a woven metal wire sieve with a mesh width of 2 mm.

In the present description, the phrase "recycled lignocellulosic fibers" includes lignocellulosic fibers obtained from used products such as used furniture, and the phrase "recycled lignocellulosic fibers" also refers to lignocellulosic fibers that are waste from manufacturing processes, for example, waste including sawdust , cut end pieces, etc.).

As already described, one of the objectives of the present invention is to enable the use of recycled lignocellulosic fibers obtained from furniture. Thus, a fibreboard according to one embodiment comprises recycled lignocellulosic fibers derived from furniture. The recycled lignocellulosic fibers may be lignocellulosic fibers obtained from disintegrated medium density fibreboard (MDF) and/or high density fibreboard (HDF), particle board, wood based boards such as oriented strand board (OSB) and plywood, or residues solid wood, such as parts of solid wood objects (for example, cut ends) or sawdust. Typically, recycled lignocellulosic fibers are obtained from more than one source. The disintegration of objects containing lignocellulosic fibers can be carried out in various ways or combinations of ways. Suitable disintegration methods include crushing, grinding, milling and refining. Typically, sequences of such processes can be used to reduce particle size in steps, such as crushing followed by grinding and/or milling. The fiber board preferably contains at least 25% by weight, more preferably at least 50% by weight. (at a moisture content of 6%) recycled lignocellulosic fibers. Such recycled lignocellulosic fibers can be obtained from disintegrated MDF boards and/or HDF boards, particle boards, wood-based boards such as oriented strand board (OSB) and plywood, or solid wood residues. Recyclable lignocellulosic fibers are preferably obtained from the wood processing industry such as the timber industry, the production of wood-based panels and the furniture industry, and/or consumer waste such as used furniture. The present invention has been found to be well suited for incorporating lignocellulosic fibers from various types of boards and panels. As is known in the art, boards and panels require recycling. This is especially true for MDF boards and/or HDF boards. According to one implementation variant, fiberboard contains at least 25% of the mass. recycled lignocellulosic fibers obtained from disintegrated MDF boards and/or HDF boards, particle boards, wood boards such as oriented strand board (OSB) and plywood, at least 25% of the mass. recycled lignocellulosic fibers obtained from disintegrated MDF boards and/or HDF boards.

The present fibreboard typically has a thickness of 7 mm or less. Thus, the thickness of the fibreboard can be between 0.5 and 7 mm. The fibreboard preferably has a thickness of 1 to 6 mm, and even more preferably 2 to 4 mm.

In addition to lignocellulosic fibers, the fibreboard also contains a binding agent. The binding agent is usually added to the fibers separately. Examples of binders include MUF (melamine urea formaldehyde resin), MDI (methylene diphenyl isocyanate) and lignin (in addition to the lignin contained in the fibers). The binder is added to bind the fibers together when they are pressed, and the binder ensures the formation of the fibreboard.

In one embodiment, the coupling agent is an isocyanate. The isocyanate may be a methylene diphenyl diisocyanate (MDI), eg 4,4'-methylene diphenyl diisocyanate, or a polymethylene polyphenylene isocyanate, eg a polymethylene polyphenylene isocyanate containing a 4,4'-methylene diphenyl diisocyanate moiety. According to this embodiment, the amount of binder in the fiberboard can be from 1 to 10 wt%. calculated on the final weight of the fibreboard. The amount of binding agent is preferably from 2 to 9% of the mass. based on the final mass of fiberboard and more preferably from 2.5 to 8% of the mass. calculated on the final weight of the fibreboard.

In an alternative but less preferred embodiment, the coupling agent is a urea-formaldehyde resin or a melamine-modified urea resin. According to such an implementation option, the amount of binder in the fiberboard can be from 5 to 20% of the mass. calculated on the final weight of the fibreboard. The amount of binder in the fiberboard is preferably 6 to 16% by weight. calculated on the final weight of the fibreboard.

As is known to the person skilled in the art, lignocellulosic fibers are obtained from the dry matter of plants, such as wood. The fibers are composed of cellulose and hemicellulose tightly bound to lignin, which is a cross-linked phenolic polymer.

The fibreboard may be a single layer board. In accordance with some implementation options, it may be preferable to use fiberboard with more than one layer. For example, it may be preferable to provide the fibreboard with a surface layer located on the fibreboard, in addition to an additional layer, which may be referred to as a core layer. Such a surface layer can provide a more secure attachment of a top layer, such as paint or veneer, subsequently applied to the fibreboard. In addition, the surface layer may contain a large amount of fine fibers, thus giving the visual impression of a smoother surface.

According to one embodiment, at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm and at least 50% of the mass. (at a moisture content of 6%) pass through a woven metal wire screen with a mesh width of 630 μm, and the binding agent is present in at least two connected layers, that is, in the first and second layers. Typically, the layers are connected to each other by pressing the lignocellulosic fibers and the binding agent that are in each layer together. According to this embodiment, from 10% of the mass. up to 50% wt. (at a moisture content of 6%) lignocellulosic fibers of the first layer do not pass through a woven metal wire screen with a mesh width of 630 μm. Thus, the first layer contains a portion of fibers of an intermediate size, i. e. fibers passing through a woven metal wire sieve with a mesh width of 3 mm, but not passing through a woven metal wire sieve with a mesh width of 630 μm. However, the first layer also contains small fibers. These fine fibers are present throughout the first layer to improve the structural integrity of the first layer. At least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire screen with a mesh width of 630 μm. Preferably at least 25% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire screen with a mesh width of 315 μm. Also preferably at least 10% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire screen with a mesh width of 125 μm. In contrast, the second layer contains a large number of small fibers. More than 90% wt., 95% wt. or even more than 99% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 630 μm. In addition, at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 315 μm. Usually at least 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen even with a mesh width of 125 μm. As already noted, the proportion of fine fibers in the second layer is greater than in the first layer. Thus, the average particle size of the second layer is smaller than the average particle size of the first layer.

The second layer is usually thinner than the first layer, which may be referred to as the main layer or the center layer. The second layer may have the same mass as the first layer, although the mass of the second layer is usually less than the mass of the first layer. The weight of the second layer is preferably less than 50% of the weight of the first layer. The weight of the second layer may even be less than 30% of the weight of the first layer. The first layer is preferably a core layer comprising 30 to 90%, more preferably 40 to 90%, most preferably 60 to 85% of the total weight of the board.

According to one embodiment, at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm and at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a 630 µm woven metal wire screen and the binding agent is present in at least three connected layers, i.e. the first, second and third layers. Typically, the layers are joined by pressing the lignocellulosic fibers and the binder present in each layer together. Although not required, the second and third layers are usually located on opposite sides of the first layer to provide a surface layer on the sides of the fibreboard. The first layer is the central layer. According to one implementation variant of the fibreboard contains at least three connected layers, from 10% of the mass. up to 50% wt. (at a moisture content of 6%) lignocellulosic fibers of the first layer do not pass through a woven metal wire screen with a mesh width of 630 μm. Thus, the first layer contains a portion of fibers of an intermediate size, i. e. fibers passing through a woven metal wire sieve with a mesh width of 3 mm, but not passing through a woven metal wire sieve with a mesh width of 630 μm. However, the first layer also contains small fibers. At least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire screen with a mesh width of 630 μm. Preferably at least 25% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire screen with a mesh width of 315 μm. Also preferably at least 10% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire screen with a mesh width of 125 μm.

On the contrary, the second layer includes a large number of small fibers. More than 90% wt., 95% wt. or even more than 99% (at a moisture content of 6%) of the lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 630 μm. In addition, at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 315 μm. Usually at least 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen even with a mesh width of 125 μm. As already noted, the number of fine fibers in the second layer is greater than in the first layer.

The third layer also contains a large number of small fibers. More than 90% wt., 95% wt. or even more than 99% (at a moisture content of 6%) of the lignocellulosic fibers of the third layer pass through a woven metal wire screen with a mesh width of 630 μm. In addition, at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the third layer pass through a woven metal wire screen with a mesh width of 315 μm. Usually at least 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the third layer pass through a woven metal wire screen even with a mesh width of 125 μm. As already noted, the number of small fibers in the third layer is greater than in the first layer.

Although not required, the particle size distribution of the lignocellulosic fiber is usually the same for the second and third layers. In addition, the average particle size in the second and third layers, respectively, is smaller than in the first layer.

The second and third layers are usually thinner than the first layer, which may be referred to as the base layer (or center layer if the second and third layers are on opposite sides of the first layer). The second and third layers may have the same mass as the first layer, although the mass of each of the second or third layers is usually less than the mass of the first layer. Preferably, the weight of each of the second and third layers is less than 50% of the weight of the first layer. The weight of each of the second and third layers may even be less than 30% of the weight of the first layer. Preferably the first layer is a core layer comprising 30 to 90%, more preferably 40 to 90%, most preferably 60 to 85% of the total weight of the board.

According to a second aspect of the invention, there is provided a process for producing a fiberboard containing lignocellulosic fibers and a binder pressed together. The fibreboard is generally the kind of fibreboard as described above. Thus, the characteristics of the fibreboard already described with regard to the fibreboard are equally applicable to the process for producing a fibreboard containing lignocellulosic fibers and a binder pressed together.

A method for producing a fiberboard containing lignocellulosic fibers and a binder pressed together includes the following steps:

- mixing lignocellulosic fibers with a binder;

- placing a mixture of lignocellulosic fibers and a binder as at least a first layer (as indicated below, an additional layer (s) containing lignocellulosic fibers and a binder may be present) on the surface; and

- pressing the first layer, consisting of mixed lignocellulosic fibers and a binder, to form a fibreboard.

While at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers are lignocellulosic fibers passing through a woven metal wire sieve with a mesh width of 3 mm. In addition, at least 50% of the mass. lignocellulosic fibers are lignocellulosic fibers that pass through a woven metal wire screen with a mesh width of 630 µm. As already mentioned, small lignocellulosic fibers (eg, lignocellulose fibers passing through a 630 µm woven metal wire mesh) are present throughout the board, not just on its surface. At any given location on the fibreboard, the content of lignocellulosic fibers passing through a 630 µm woven metal wire mesh, preferably a 500 µm woven metal wire mesh, is preferably at least 25% by weight, more preferably 25% mass. In particular, at any given location in the first layer, the content of lignocellulosic fibers passing through a woven metal wire sieve with a mesh width of 630 µm, preferably through a woven metal wire sieve with a mesh width of 500 µm, is preferably at least 25% by weight, more preferably 25% of the mass. In addition, the layer(s) of mixed lignocellulosic fibers and binder is pressed so that the resulting fibreboard has a total thickness of 0.5 to 7 mm and a density of at least 930 kg/m ³ . The density of the resulting fibreboard can be influenced by controlling the pressure during the pressing step. When pressing material located on surfaces located at a certain distance, the pressure depends on the amount of material being pressed - the more material, the higher the density of the resulting fibreboard. The fibreboard typically has a thickness of 0.5 to 7 mm, or may have a thickness of 1 to 6 mm, such as 2 to 4 mm.

Because the fibers used to make fibreboard are typically recycled lignocellulosic fibers, their moisture content is typically higher than that of the new lignocellulosic fiber used in HDF production. Thus, the moisture content of the lignocellulosic fibers to be laid and pressed into the fibreboard can be at least 12%. The moisture content is preferably in the range of 14 to 18%.

The surface on which the lignocellulosic fibers and the binder are applied as a layer may be an endless moving belt. The tape may be a closed smooth tape or a wire mesh tape. An endless moving belt can be used to feed the layer of lignocellulosic fibers and binder into the press.

Typically, the press is a continuous or discontinuous wood-based panel press. Such presses are available, for example, from Dieffenbacher GmbH, Eppingen, Germany and G. Siempelkamp GmbH & Co. KG, Krefeld, Germany. The layer of lignocellulosic fibers and binder can be pressed at a temperature of from 100 to 250°C, for example from 125 to 180°C on a hot plate. The applied pressure may be from 0.5 to 10 N/mm ² , for example from 1 to 6 N/mm ² .

While the acceptable content of lignocellulose fibers in a mixture of lignocellulose fibers and a binder is at least 50% of the mass. (at a moisture content of 6%), the content of lignocellulosic fibers in a mixture of lignocellulosic fibers and a binder is usually higher. According to one implementation variant, the content of lignocellulose fibers in a mixture of lignocellulose fibers and a binder is at least 70, 80, 85 or 90% of the mass. (at a moisture content of 6%). This provides an even higher strength of the fibreboard.

Preferably, not all lignocellulosic fibers in the mixture of lignocellulosic fibers and binder are small fibers. Thus, lignocellulosic fibers in a mixture of lignocellulosic fibers and a binder may meet one or more of the following criteria:

- at least 20, 25, 30 or 35% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a woven metal wire sieve with a mesh width of 125 microns; and/or

- at least 15, 20, 25 or 30% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a 315 µm woven metal wire mesh screen; and/or

- at least 5, 10, 15 or 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a woven metal wire sieve with a mesh width of 630 μm.

It is further preferred that some of the lignocellulosic fibers in the mixture of lignocellulosic fibers and the binder are fine fibers or even very fine fibers. Thus, lignocellulosic fibers in a mixture of lignocellulosic fibers and a binder may meet one or both of the following criteria:

- at least 5, 10, 15 or 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 125 microns; and/or

- at least 10, 15, 20, 25 or 30% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire screen with a mesh width of 315 microns.

Although a small amount of lignocellulosic fibers in a mixture of lignocellulosic fibers and a binder may be very large fibers, it is preferable if this number is limited. According to one embodiment, at least 97.5% of the mass. (at a moisture content of 6%), for example, at least 99.0% of the mass. (at a moisture content of 6%), lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm, more preferably pass through a woven metal wire sieve with a mesh width of 2 mm.

As already described, one of the objectives of the present invention is to enable the use of recycled lignocellulosic fibers obtained from furniture. Thus, a mixture of lignocellulosic fibers and a binder, in accordance with one embodiment, contains recyclable lignocellulosic fibers. The recycled lignocellulosic fibers may be lignocellulosic fibers obtained from disintegrated medium density fibreboard (MDF) and/or high density fibreboard (HDF), particle board, wood based boards such as oriented strand board (OSB) and plywood, or residues solid wood, such as parts of solid wood or sawdust. Typically, recycled lignocellulosic fibers are obtained from more than one source. The disintegration of objects containing lignocellulosic fibers can be carried out in various ways or combinations of ways. Suitable disintegration methods include crushing, grinding, grinding and refining. Typically, sequences of such processes can be used to reduce particle size in steps, such as crushing followed by grinding and/or milling. A mixture of lignocellulosic fibers and a binder preferably contains at least 25% wt., more preferably at least 50% wt. (at a moisture content of 6%) recycled lignocellulosic fibers. Such recycled lignocellulosic fibers can be obtained from disintegrated MDF boards and/or HDF boards, particle boards, wood-based boards such as oriented strand board (OSB) and plywood, or solid wood residues. Recyclable lignocellulosic fibers are preferably obtained from the wood processing industry such as the timber industry, the production of wood-based panels and the furniture industry, and/or consumer waste such as used furniture. The present invention has been found to be well suited for incorporating lignocellulosic fibers from various types of boards and panels. As is known in the art, boards and panels require recycling. This is especially true for MDF boards and/or HDF boards. According to one implementation variant, fiberboard contains at least 25% of the mass. recycled lignocellulosic fibers obtained from disintegrated MDF boards and/or HDF boards, particle boards, wood boards such as oriented strand board (OSB) and plywood, at least 25% of the mass. recycled lignocellulosic fibers obtained from disintegrated MDF boards and/or HDF boards.

The present fibreboard typically has a thickness of 7 mm or less. Thus, the thickness of the fibreboard can be between 0.5 and 7 mm. The fibreboard preferably has a thickness of 1 to 6 mm, and even more preferably 2 to 4 mm. Fibreboards of this thickness can be produced with high mechanical strength. In addition, fibreboards with this combination of mechanical strength and thickness find many applications, for example in the furniture industry, for example for the manufacture of cabinets, drawers, bookshelves, etc.

In addition to lignocellulosic fibers, the fibreboard also contains a binding agent. Examples of binding agents include MUF (melamine urea formaldehyde resin), MDI (methylene diphenyl isocyanate) and lignin (in addition to the lignin contained in the fibers). The binder is added to bind the fibers together when they are pressed, and the binder ensures the formation of the fibreboard.

In one embodiment, the coupling agent is an isocyanate. The isocyanate may be a methylene diphenyl diisocyanate (MDI), eg 4,4'-methylene diphenyl diisocyanate, or a polymethylene polyphenylene isocyanate, eg a polymethylene polyphenylene isocyanate containing a 4,4'-methylene diphenyl diisocyanate moiety. According to this embodiment, the amount of binder in the mixture of lignocellulosic fibers and binder may be from 1 to 10% of the mass. The amount of binder is preferably from 2 to 9% of the mass. and more preferably from 2.5 to 8% of the mass.

In an alternative but less preferred embodiment, the coupling agent is a urea-formaldehyde resin or a melamine-modified urea resin. According to this embodiment, the amount of binder in the mixture of lignocellulosic fibers and the binder may be from 5 to 20 wt%. The amount of binder in the mixture of lignocellulosic fibers and binder is preferably from 6 to 16% of the mass.

As already noted, lignocellulosic fibers contain fibers of various sizes. To control the size distribution of lignocellulosic fibers, the method may include an additional sizing step such as classifying, selecting, sieving, or sifting lignocellulosic fibers before they are mixed with a binder. The lignocellulosic fibers are preferably subjected to a disintegration step prior to the fiber sizing step. Disintegration has already been described in this document above.

In addition, the size distribution of lignocellulosic fibers can be controlled by mixing two or more parts of lignocellulosic fibers having different size distributions. In one embodiment, the lignocellulosic fibers to be mixed with the binder are obtained by mixing a first portion of the lignocellulosic fibers with a second portion of the lignocellulosic fibers. In order to control the size distribution of the lignocellulosic fibers to be mixed with the binder, the size distribution of the lignocellulosic fibers in the first part is different from the size distribution of the lignocellulosic fibers in the second part. Preferably, the first and/or second portion of the lignocellulosic fibers has been obtained by sizing the lignocellulosic fibers to control the size distribution of the lignocellulosic fibers in the respective portion.

As already noted, the resulting fibreboard may be a single layer board. In accordance with some implementation options, it may be preferable to use fiberboard with more than one layer. For example, it may be preferable to provide the fibreboard with a surface layer. Such a surface layer can provide a stronger bond for a top layer, such as paint or veneer, subsequently applied to the fibreboard. In addition, the surface layer may contain a large amount of fine fibers, thus giving the visual impression of a smoother surface.

In one embodiment, the process for making fiberboard includes the additional step of forming a second layer of lignocellulosic fibers and bonding agent adjacent to the first layer of mixed lignocellulosic fibers and bonding agent prior to pressing the first layer. After pressing two layers of lignocellulosic fibers and a binder, a multilayer fibreboard is formed. According to this implementation:

- at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the first layer pass through a woven metal wire sieve with a mesh width of 3 mm, from 10 to 50% of the mass. (at a moisture content of 6%) lignocellulose fibers of the first layer do not pass through a woven metal wire sieve with a cell width of 630 μm, and at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire sieve with a mesh width of 630 μm; and

- at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a mesh width of 3 mm, more than 90% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a cell width of 630 μm, and at least 40% of the mass. (at a moisture content of 6%) the lignocellulosic fibers (in free form) of the second layer pass through a 315 µm woven metal wire screen. The average particle size of the second layer is smaller than the first layer. As noted, small lignocellulosic fibers (eg, lignocellulosic fibers passing through a 630 µm woven metal wire screen) are present throughout the first layer. At any given location in the first layer, the content of lignocellulosic fibers passing through a woven metal wire sieve with a mesh width of 630 µm, preferably through a woven metal wire sieve with a mesh width of 500 µm, is preferably at least 25% by weight, more preferably 25% wt. In addition, the total thickness of the fiberboard laminate is 0.5 to 7 mm.

According to this embodiment, it is preferable that at least 25% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer passed through a woven metal wire sieve with a mesh width of 315 μm. It is also preferred that at least 10 wt. (at a moisture content of 6%) lignocellulosic fibers of the first layer passed through a woven metal wire sieve with a mesh width of 125 μm. In addition, usually at least 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a sieve of metal wire even with a width of 125 microns.

The second layer preferably contains a large number of small fibers. Thus, more than 90% wt., 95% wt. or even more than 99% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 630 μm. In addition, at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 315 μm. Usually at least 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen even with a mesh width of 125 μm. As already noted, the proportion of fine fibers in the second layer is higher than in the first.

According to such an implementation for obtaining a multilayer fibreboard, the method includes the following steps of forming a second layer of lignocellulosic fibers and a binder on the first side of the first layer and forming a third layer of lignocellulosic fibers and a binder on the second side of the first layer. The further steps of forming the second and third layers, respectively, are carried out before pressing. After pressing three layers of lignocellulosic fibers and a binder, a multilayer fibreboard containing at least three layers is formed. According to this implementation:

- at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the first layer pass through a woven metal wire sieve with a mesh width of 3 mm, from 10 to 50% of the mass. (at a moisture content of 6%) lignocellulose fibers of the first layer do not pass through a woven sieve of metal wire with a mesh width of 630 μm, and at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire sieve with a mesh width of 630 μm;

- at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a mesh width of 3 mm, more than 90% of the mass. lignocellulose fibers of the second layer pass through a woven sieve of metal wire with a cell width of 630 μm, and at least 40% of the mass. lignocellulose fibers (in free form) of the second layer pass through a sieve of metal wire 315 µm wide; and

- at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the third layer pass through a woven metal wire sieve with a mesh width of 3 mm, more than 90% of the mass. lignocellulose fibers (in free form) of the third layer pass through a woven sieve of metal wire with a mesh width of 630 μm, and at least 40% of the mass. lignocellulosic fibers (in the free state) of the third layer pass through a 315 µm woven metal wire screen. The average particle size of the second and third layers is smaller than the first layer. As noted, fine lignocellulosic fibers (eg, lignocellulosic fibers passing through a 630 µm woven metal wire mesh) are present throughout the first layer. At any given location in the first layer, the content of lignocellulosic fibers passing through a woven metal wire sieve with a mesh width of 630 µm, preferably through a woven metal wire sieve with a mesh width of 500 µm, is preferably at least 25% by weight, more preferably 25% wt. In addition, the total thickness of the fiberboard laminate is 0.5 to 7 mm.

According to this embodiment, it is preferable that at least 25% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer passed through a woven metal wire sieve with a mesh width of 315 μm. It is also preferred that at least 10 wt. (at a moisture content of 6%) lignocellulosic fibers of the first layer passed through a woven metal wire sieve with a mesh width of 125 μm. In addition, as a rule, at least 20% of the mass. (at a moisture content of 6%) the lignocellulosic fibers of the second layer as well as the third layer pass through a woven metal wire screen even with a mesh width of 125 μm.

The second layer preferably contains a large number of small fibers. Thus, more than 90% wt., 95% wt. or even more than 99% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 630 μm. In addition, at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a sieve of metal wire with a width of 315 microns. Usually at least 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen even with a mesh width of 125 μm. As already noted, the proportion of fine fibers in the second layer is higher than in the first.

In addition, it is also preferable that the third layer contains a large amount of fine fibers. Thus, more than 90% wt., 95% wt. or even more than 99% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the third layer pass through a woven metal wire sieve with a mesh width of 630 μm. In addition, at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the third layer pass through a woven metal wire screen with a mesh width of 315 μm. Usually at least 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the third layer pass through a woven metal wire screen even with a mesh width of 125 μm.

The appearance or surface texture of the fibreboard can be affected by spraying water onto the top surface of the layer(s) of mixed lignocellulosic fibers and binder prior to being pressed into the fibreboard. Thus, in one embodiment, the method further includes the step of spraying water onto the top surface of the mixed lignocellulosic fiber layer(s) and the binder prior to pressing to form the fiberboard.

Brief description of the drawings

These and other aspects, features and advantages of the invention will be apparent and explained from the following description of embodiments of the present invention with reference to the accompanying drawings, which show:

On FIG. 1 is a process flow diagram for the production of a multilayer fiberboard containing compressed lignocellulosic fibers, according to one embodiment.

On FIG. 2 shows a three-layer fibreboard having a core layer and two surface layers. The direction of manufacture of products (see Fig. 1) is indicated in this drawing.

Detailed description

The following description will focus on one embodiment of the present invention applicable to a process for manufacturing a fiberboard containing lignocellulosic fibers from recycled furniture, HDF, etc. However, it should be understood that the invention is not limited to the specific illustrative embodiment described.

In the flow diagram shown in Fig. 1, lignocellulosic fibers obtained by crushing and grinding waste furniture, MDF boards, etc. are stored in the first hopper 1. From the first hopper 1, lignocellulosic fibers enter through the ferrous metal removal device 2 and the non-ferrous metal removal device 3 to the first sieve 4. Ferrous metal removing device 2 removes magnetic objects containing ferrous metal such as steel, and non-ferrous metal removing device 3 removes objects containing non-ferrous metals such as aluminum, copper, brass and tin. On the first sieve 4, large (> 25 mm) particles are discarded and, for example, they can be returned to the stage of crushing and disintegration of large particles carried out before the first hopper 1, while particles of medium size (from 2 to 25 mm) are loaded into the mill 5, and fine (<2 mm) particles are fed to the second sieve 6. From the second sieve 6, large particles (> 2 mm) are fed into the mill 5, particles of large and medium sizes (from 0.7 to 2 mm) are fed into the second bin 9 , particles of small and medium sizes (from 0.3 to 0.7 mm) are fed into the second bin 7, and fine (<0.3 mm) particles are fed into the third bin 8. The crushed particles from the mill 5 are fed into the fourth hopper 9. The particles from the second hopper 7, the third hopper 8 and the fourth hopper 9 are fed into the first mixer 10. In the first mixer 10 the particles from the second hopper 7, the third hopper 8 and the fourth hopper 9 are mixed with the binding agent. Similarly, particles from the second hopper 7 and the third hopper 8 are fed into the second mixer 11 for mixing with the binding agent. Before the particles from the first mixer 10 are fed onto the continuous forming belt 12, large particles (eg lumps of binder) are removed on the first sieve 13. In addition, before the particles from the second mixer 11 are fed onto the continuous forming belt 12, large particles are removed at the second sieve 14. By successively feeding particles from the second sieve 14, particles from the first sieve 13 and particles from the second sieve 14 onto the continuous forming belt 12, a three-layer fibrous mat is formed on it, which is then fed to the press 15. In In a three-layer fibrous mat, the particles from the first sieve 13 are arranged as the first layer in the form of the center layer, while the particles from the second sieve 14 are arranged as the second and third layers in the form of the upper and lower surface layers. By pressing a three-layer fibrous mat in a press 15, a fiberboard 16 (see Fig. 2) containing lignocellulosic fibers and a binding agent is obtained.

Without further specification, it is believed that a person skilled in the art can, using the previous description, use the present invention to its fullest extent. Therefore, the previous preferred specific implementation options should be considered as merely illustrative and not limiting in any way the present invention.

In the embodiment shown in FIG. 1 describes a method and equipment for the production of a fibreboard having a core layer and two surface layers located on opposite sides thereof. It should be understood that it would also be possible to change the production method and equipment for the production of fiberboard having a core layer and a surface layer on one side thereof, for example, by turning off one of the two forming sections designed to form a mixture of particles and a binder to form a surface layer. layer.

In addition, it would be possible to change the production method and equipment for the production of fibreboard having only one layer, for example, by turning off the two forming sections for forming a mixture of particles and a binder to form surface layers.

Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the particular form set forth herein. On the contrary, the present invention is limited only by the appended claims, and other embodiments other than the specific embodiments described above are equally possible within the scope of this appended claims.

In the claims, the term "comprises/comprising" does not exclude the presence of other elements or steps. In addition, although individual features may be included in different claims, they can be advantageously combined, and such inclusion in different claims does not imply that a combination of features is not possible and/or does not provide advantages.

In addition, references in the singular do not exclude the presence of the plural. Terms in the singular, "first", "second", etc. does not rule out the presence of a plural.

Examples

The following examples are merely examples and should in no way be interpreted as limiting the scope of the present invention, as the present invention is only limited by the appended claims.

As indicated below, several fibreboards have been made by mixing mixed lignocellulosic fibers with a binder. The resulting mixture of fibers was pressed to form a fibreboard, and the obtained fibreboards were tested.

Example 1 - single layer fibreboards

In example 1, several thin boards with a single fibrous layer were made and tested.

fibers

Lignocellulosic fibers were obtained by grinding and disintegrating waste furniture, HDF boards, etc. up to a size of less than 25 mm. The resulting fibers were ground using a hammer mill. All particles smaller than 1.2 and 2 mm respectively can leave the grinding chamber through 2 types of steel plates with certain holes. The retention time and hole size determine the composition of the mixture of materials (changing the number of 1.2 mm holes relative to the number of 2 mm holes can change the particle size distribution). In the examples shown, about half of the total open area was with 1.2 mm holes and half of the open area was with 2 mm holes.

Coupling agent

The binder was sprayed to break it up into very small droplets. These droplets were caught in the air stream and mixed with the milled fibers in the air stream to form a mixture of fibers which was compressed into a fibreboard. The type of bonding agent used was HuntsmanI-Bond MDF EM 4330, available from Huntsman Holland BV, Botlek-Rotterdam, The Netherlands.

Pressing

The mixture of fibers was formed into a mat by spreading it on a vacuum belt (closed tape can also be used). The formed mat was transferred to the inlet of the press and pre-compressed to reduce the volume of air in the mat. In the next step, the mat was heated and then a pressing step was performed to achieve the final thickness. In the last step, the mat was held under pressure to solidify. The press was a laboratory batch press, which was pressurized up to 5 N/mm ² .

Fiber blends

The particle size distribution of the fibers in the boards before pressing was determined in accordance with ISO 3310-1:2016 (Part 1: Analysensiebe mit Metalldrahtgewebe). All boards contained a large amount of fine fibers (particle size <0.65 mm) as well as a fairly large amount of really small fibers (particle size <0.3 mm). In Example 1, two types of fiber blends were used. The particle size distribution of these fiber blends, determined in accordance with ISO 3310-1:2016, is presented in Tables 1a and 1b below. The second mixture, mixture 2, contained only fine particles. This fiber blend was used as the surface layer (SL) in the following examples (see Example 2), while the first fiber blend, Blend 1, also containing larger fibers (particle size >0.65 mm), was used as the core layer ( CL).

Table 1a

Blend 1 Fraction size CL avg. content, % 0.125 > 0 mm 25 0.315>0.125mm twenty 0.63 > 0.315 mm 27 1.0 > 0.63 mm eighteen 2.0 > 1.0 mm 9 3.15 > 2.0 mm one > 3.15 mm 0

Table 1b

Blend 2 Fraction size SL avg. content, % 0.125 > 0 mm 35 0.315>0.125mm 25 0.635 > 0.315 mm 40 1.0 > 0.63 mm 0 2.0 > 1.0 mm 0 3.15 > 2.0 mm 0 > 3.15 mm 0

Fiber Blend 1 was used in Fibreboards Nos. 1-3, 5, 6 and 8-13, while Fiber Blend 2 was used in Fibreboards Nos. 4 and 7. The properties of the resulting fibreboards were evaluated using a number of standard methods (Thickness: EN 324-1:1993 Moisture content EN 322:1993 Swelling (%) after 24 hours: EN 317:1993 Modulus of elasticity: EN 310:1993 Flexural strength: EN 310:1993 Internal bond: EN 319: 1993; Surface strength: EN 311:2002). The results are presented in table 2.

Table 2 - Properties of tested fibreboards Nos. 1-13 (underlined data: out of target value)

Test parameters one 2 3 (CTRL) four 5 6 (CTRL) 7 Target value Thickness (mm) 2.56 2.91 2.97 3.03 4.41 6.1 6.08 2-6 Moisture contents (%) 5.75 6.58 6.6 6.61 8.79 6.38 6.07 Swelling after 24 hours (%) 21.2 13.45 17.2 14.28 11.62 9.29 7.16 Modulus of elasticity (N/m ² ) 2744 3838 2100 3176 3883 1838 2240 > 2200 Bending strength (N/m ² ) 16.55 33.96 18.32 31.93 36.72 19.11 22.58 >16 Internal grip (N/ ^m2 ) 0.64 1.04 1.05 1.09 1.35 1.11 1.47 >0.5 Surface strength (N/m ² ) 1.31 2.43 1.06 1.38 1.84 1.63 1.93 >0.8 Density distribution (average) (kg/m ³ ) 946 982 810 1035 1005 883 932 >930

Test parameters eight 9 ten eleven 12 13 Target value Thickness (mm) 2.66 2.76 3.27 3.04 3.05 2.92 2-6 Moisture contents (%) ND ND ND ND ND ND Swelling after 24 hours (%) ND ND ND ND ND ND Modulus of elasticity (N/m ² ) 2976 3877 3166 2692 3645 3473 > 2200 Bending strength (N/m ² ) 31.53 38.79 29.13 22.86 30.26 28.88 >16 Internal grip (N/ ^m2 ) 3.27 3.62 2.35 2.62 3.2 3.59 >0.5 Surface strength (N/m ² ) ND ND ND ND ND ND >0.8 Density distribution (average) (kg/m ³ ) 1088 1115 991.9 979.6 1040 1070.8 >930

As can be seen from Table 2, fibreboards must be sufficiently dense (> 930 kg/m ³ ) to have the required properties. Plates 3 (ctrl) and 6 (ctrl), having a density of less than 900 kg/m ³ did not reach the target modulus of elasticity. The density of the boards can be controlled by the pressure applied when pressing the boards.

Example 2 - multilayer boards

In example 2, several thin boards with 3 layers of fibers (one center layer and two surrounding surface layers) were made and tested. The central layer contained fiber blend 1 (see above), while the surface layers contained fiber blend 2 (see above).

fibers

Fiber blends were prepared in the same manner as in Example 1.

Coupling agent

The binder used was the same as in Example 1, and the mixture of binder and fibers was prepared in the same manner as in Example 1.

Pressing

Fiber mats compressed to form the 4 fibreboards shown in Table 3 were obtained in the same manner as in Example 1 with three layers stacked on top of each other. The first layer (center layer) consisted of a mixture of fibers 1, while the second and third layers (surface layers) consisted of a mixture of fibers 2. The mass fraction of the central layer was 80% wt., and the mass fraction of each of the surface layers was 10% wt. In order to obtain fibreboards of different densities, different pressures were applied when pressing the mat of fibers.

The properties of the obtained fibreboards were evaluated in the same way as in example 1.

Table 3 - Properties of tested fibreboards Nos. 14-17 (underlined data: out of target value)

Test parameters 14 (CTRL) 15 (CTRL) 16 (CTRL) 17 Target value Thickness (mm) 3.57 3.17 3.49 2.82 2-6 Modulus of elasticity (N/m ² ) 1391 2186 1414 3074 > 2200 Bending strength (N/m ² ) 8.49 fifteen 7.61 26.05 >16 Internal grip (N/ ^m2 ) 0.86 1.54 0.8 2.73 >0.5 Density distribution (average) (kg/m ³ ) 766 877.8 747 1036 >930

As can be seen from Table 3, multilayer boards containing fine particles must also be sufficiently dense (> 930 kg/m ³ ) to have the required properties. Boards 14 (ctrl) to 16 (ctrl) having a density of less than 900 kg/m ³ did not reach the target modulus of elasticity. As can be seen for board 17, the density of the boards can be varied by changing the pressure applied when pressing the board (board 17 contains about the same amount of fibers as the control boards).

Example 3 - comparative example

Additional control boards (18-20) with a higher proportion of larger fibers (75 wt. % of 1 to 3 mm fibers and 25 wt. % of less than 1 mm fibers) were made in the same manner as in Example 1. In addition, the properties of the control boards were evaluated in the same manner as in Example 1 and compared with the corresponding properties of the boards of the invention (ie boards 11 and 12). The results are presented in table 4.

Table 4

Test parameters 18 (ctrl) 19 (ctrl) 20 (ctrl) eleven 12 Thickness (mm) 2.85 2.8 2.9 3.04 3.05 Modulus of elasticity (N/m ² ) 2679 2589 2981 2692 3645 Bending strength (N/m ² ) 22.91 23.27 27.15 22.86 30.26 Internal grip (N/ ^m2 ) 3.07 2.96 2.81 2.62 3.2 Density distribution (average) (kg/m ³ ) 947 960 1011 979.6 1040

As can be seen from table 4, the properties of the plates 11 and 12 according to the present invention are similar to the properties of the control plates 18-20. Thus, it was confirmed that a high proportion of fine fibers (<1 mm) does not indeed lead to deterioration of properties, provided that the board is dense (density > 930 kg/m ³ ). In addition, the surface of the fibreboards was smoother compared to the surface of the boards containing blend 1 only (ie fibreboards Nos. 1-3, 5, 6, 8-13).

Claims (24)

1. A fiberboard containing lignocellulosic fibers and a binder pressed together, wherein: the fiberboard has a thickness of 0.5 to 7 mm; the content of lignocellulosic fibers in the fiberboard is at least 50% of the mass. (at a moisture content of 6%); at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm; at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 630 microns; and the density of the fibreboard is at least 930 kg/m ³ . 2. A fibreboard according to claim 1, the thickness of which is 1 to 6 mm, preferably 2 to 4 mm. 3. Fiberboard according to any one of paragraphs. 1 or 2, in which the content of lignocellulose fibers is at least 70, 80, 85 or 90% of the mass. (at a moisture content of 6%). 4. Fiberboard according to any one of paragraphs. 1-3, in which at least 15, 20, 25 or 30% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a 315 µm woven metal wire mesh screen; and/or in which at least 5, 10, 15 or 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a woven metal wire sieve with a mesh width of 630 μm. 5. Fiberboard according to any one of paragraphs. 1-4, in which at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 2 mm; and/or in which at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 500 μm. 6. Fiberboard according to any one of paragraphs.1-5, in which at least 97.5% of the mass. (at a moisture content of 6%), for example, at least 99.0% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm, preferably at least 97.5% of the mass. (at a moisture content of 6%), for example, at least 99.0% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire screen with a mesh width of 2 mm. 7. Fiberboard according to any one of paragraphs. 1-6, which contains recycled lignocellulosic fibers obtained by disintegration, such as crushing and/or grinding and/or grinding and/or refining, medium density fibreboard (MDF) and/or high density fibreboard (HDF ), particle boards, wood-based panels such as oriented strand board (OSB) and plywood, or solid wood residues such as parts of solid wood or sawdust; fibreboard preferably contains at least 25% of the mass. (at a moisture content of 6%) recycled lignocellulosic fibers obtained from the disintegration of MDF boards and/or HDF boards, particle boards, wood-based panels such as oriented strand board (OSB) and plywood, and solid wood residues, preferably recycled lignocellulosic fibers derived from the wood-related industry such as the timber industry, the production of wood-based panels and the furniture industry, and/or consumer waste such as used furniture; more preferably the fibreboard contains at least 25% of the mass. recycled lignocellulosic fibers obtained from disintegrated MDF boards and/or HDF boards, particle boards, wood-based boards such as oriented strand board (OSB) and plywood. 8. Fiberboard according to claim 7, containing at least 25% of the mass. recycled lignocellulosic fibers obtained from disintegrated MDF boards and/or HDF boards. 9. Fiberboard according to any one of paragraphs. 1-8, wherein the coupling agent is a resin containing an isocyanate component, preferably a methylene diphenyl diisocyanate (MDI) isocyanate component, e.g. 4,4'-methylene diphenyl diisocyanate or polymethylene polyphenylene isocyanate, e.g. , the amount of binder is preferably from 1 to 10 wt. -%, more preferably from 2 to 9 wt.%. and most preferably from 2.5 to 8% of the mass. calculated on the final weight of the fibreboard. 10. Fiberboard according to any one of paragraphs. 1-8, in which the binder is a urea-formaldehyde resin or a melamine-modified urea resin, the amount of the binder is preferably 5 to 20% by mass, more preferably 6 to 16% by mass. calculated on the final weight of the fibreboard. 11. Fiberboard according to any one of paragraphs. 1-10, in which lignocellulose fibers and a binding agent are present in at least two connected layers, while: from 10 to 50% of the mass. (at a moisture content of 6%) lignocellulose fibers of the first layer do not pass through a woven sieve of metal wire with a width of 630 μm and at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire sieve with a mesh width of 630 μm; and more than 90% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a mesh width of 630 μm and at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 315 μm. 12. The fiberboard of claim. 11, in which the second layer has the same or less weight than the first layer, the weight of the second layer is preferably less than 50%, more preferably less than 30% of the weight of the first layer, the first layer is preferably the center layer , comprising from 30 to 90%, more preferably from 40 to 90%, most preferably from 60 to 85% of the total weight of the board. 13. Fiberboard according to any one of paragraphs. 1-12, in which lignocellulose fibers and a binder are present in at least three connected layers, while: from 10 to 50% of the mass. (at a moisture content of 6%) lignocellulose fibers of the first layer do not pass through a woven sieve of metal wire with a mesh width of 630 μm, and at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer pass through a woven metal wire sieve with a mesh width of 630 μm; more than 90% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a mesh width of 630 μm and at least 40% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the second layer pass through a woven metal wire screen with a mesh width of 315 microns; and more than 90% of the mass. (at a moisture content of 6%) lignocellulose fibers of the third layer pass through a woven metal wire sieve with a cell width of 630 μm and at least 40% of the mass. lignocellulose fibers of the third layer pass through a woven metal wire mesh with a mesh width of 315 microns; and wherein the second and third layers are preferably located on opposite sides of the first layer. 14. The fiberboard of claim. 13, in which each of the second and third layers have the same or less weight than the first layer, preferably the weight of each of the second and third layers is less than 50%, more preferably less than 30% of the weight of the first layer , preferably the first layer is a core layer comprising 30 to 90%, more preferably 40 to 90%, most preferably 60 to 85% of the total weight of the board. 15. A method of obtaining a fiberboard containing lignocellulosic fibers and a binder pressed together, the method includes the following steps: mixing lignocellulose fibers and a binder, with at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 3 mm, and at least 50% of the mass. lignocellulosic fibers pass through a woven metal wire screen with a mesh width of 630 µm; applying a mixture of lignocellulosic fibers and a binding agent as at least a first layer to the surface; and pressing at least a first layer of the mixture of lignocellulosic fibers and a binder into a fiber board having a total thickness of 0.5 to 7 mm and a density of at least 930 kg/m ³ . 16. The method according to p. 15, in which: at least 95% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 2 mm; and/or at least 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers pass through a woven metal wire sieve with a mesh width of 500 microns; and/or the moisture content of the lignocellulosic fibers to be applied and pressed is at least 12%, and preferably in the range of 14 to 18%. 17. The method according to p. 15 or 16, in which at least 15, 20, 25 or 30% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a 315 µm woven metal wire mesh screen; and/or in which at least 5, 10, 15 or 20% of the mass. (at a moisture content of 6%) lignocellulosic fibers do not pass through a woven metal wire sieve with a mesh width of 630 μm. 18. The method according to any one of paragraphs. 15-17, in which at least part of the lignocellulosic fibers was obtained by disintegration, such as crushing and/or grinding and/or grinding and/or refining, medium density fibreboard (MDF) and/or high density fibreboard (HDF), particle boards, wood-based panels such as oriented strand board (OSB) and plywood, or solid wood residues such as parts of solid wood objects or sawdust, preferably lignocellulosic fibers contain recyclable lignocellulosic fibers, preferably at least 25% wt. lignocellulosic fibers are recycled lignocellulosic fibers obtained from the wood-related industry such as the timber industry, the production of wood-based panels and the furniture industry, and/or consumer waste such as used furniture. 19. The method according to p. 18, in which the fiberboard contains at least 25% of the mass. recycled lignocellulosic fibers obtained from disintegrated MDF boards and/or HDF boards. 20. The method of obtaining fibreboard according to any one of paragraphs. 15-19, further comprising a sizing step, such as classifying, selecting, screening, or screening, of the lignocellulosic fibers before mixing them with a binder to control the size distribution of the lignocellulosic fibers, the lignocellulosic fibers are preferably subjected to a disintegration step before the fiber sizing step. 21. The method of obtaining fibreboard according to any one of paragraphs. 15-20, in which the first part of the lignocellulosic fibers is mixed with the second part of the lignocellulosic fibers to obtain lignocellulosic fibers for mixing with a binder, the size distribution of the lignocellulosic fibers in the first part is different from the size distribution of the lignocellulosic fibers in the second part; preferably, the first and/or second portions of the lignocellulosic fibers have been obtained by sizing the lignocellulosic fibers to control the size distribution of the lignocellulosic fibers in these portions. 22. The method of obtaining fibreboard according to any one of paragraphs. 15-21, further comprising the step of forming a second layer of lignocellulosic fibers and a binder adjacent to the first layer of mixed lignocellulosic fibers and a binder, before pressing the first layer, wherein a multilayer fibreboard is obtained by pressing two layers of lignocellulosic fibers and a binder, while: from 10% of the mass. up to 50% wt. (at a moisture content of 6%) lignocellulosic fibers of the first layer do not pass through a woven sieve of metal wire with a mesh width of 630 μm; and at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a mesh width of 3 mm, more than 90% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a cell width of 630 μm, and at least 40% of the mass. (at a moisture content of 6%) the lignocellulosic fibers (in free form) of the second layer pass through a 315 µm woven metal wire screen. 23. The method of obtaining fibreboard according to any one of paragraphs. 15-22, further comprising the steps of: forming a second layer of lignocellulosic fibers and a binding agent on a first side of the first layer; and forming a third layer of lignocellulosic fibers and a binder on the second side of the first layer, additional steps of forming the second and third layers are performed respectively before pressing the first layer, whereby, after pressing the three layers of lignocellulosic fibers and a binder, a multilayer fibreboard is obtained, in which from 10 to 50% of the mass. (at a moisture content of 6%) lignocellulosic fibers of the first layer do not pass through a woven sieve of metal wire with a mesh width of 630 μm; and at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the second layer pass through a woven metal wire sieve with a mesh width of 3 mm, more than 90% of the mass. lignocellulose fibers of the second layer pass through a woven sieve of metal wire with a cell width of 630 μm, and at least 40% of the mass. lignocellulosic fibers (in free form) of the second layer pass through a 315 µm woven metal wire screen; at least 95% of the mass. (at a moisture content of 6%) lignocellulose fibers of the third layer pass through a woven metal wire sieve with a mesh width of 3 mm, more than 90% of the mass. lignocellulose fibers (in free form) of the third layer pass through a woven sieve of metal wire with a mesh width of 630 μm, and at least 40% of the mass. lignocellulosic fibers (in free form) of the third layer pass through a 315 µm woven metal wire screen. 24. The method of obtaining fibreboard according to any one of paragraphs. 15-23, further comprising the step of spraying water onto the upper surface of the layer(s) of mixed lignocellulosic fibers and a binder prior to pressing to form a fiberboard.

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