ES2718057T3 - Procedure for the manufacture of a material of wood shavings and hardeners for aminoplastics used - Google Patents

Description

DESCRIPTION

Procedure for the manufacture of a material of wood shavings and hardeners for aminoplastics used

The present invention relates to a process for the manufacture of wood chip materials according to claim 1 and to the use of a hydrothermally and mechanically decomposed hydrothermally-containing material, as hardener for an aminoplast resin according to claim 20.

The materials based on chips, the so-called wood chip materials, are composed of a crushed wood material that can be pressed forming both monolayer plates and multilayer plates. The classification of wood chip materials is usually carried out in accordance with EN 309. Important classification characteristics are the manufacturing process (extruded or pressed flat), the surface consistency (rough, sanded, pressed-coated), the shape and the size of the wood materials used (wood shavings, wood flakes, wood slices, wood strands), the plate structure (monolayer or multilayer) and the intended use.

Since the solid wood joint is largely annulled in wood chip materials, these plates have the direction of the plate plane, ie in the direction of the length and width of the plate, practically the width of the plate. same characteristics of swelling and contraction. Wood chip materials are used, for example, in construction as an insulating, building or coating element, in the furniture industry and as a floor covering.

In the manufacture of wood chip materials, a great use of wood material can be guaranteed. In addition to forest wood, residual wood from industry and used wood is also used.

The chip materials are manufactured from wood material of fine particles of the most diverse types of wood by adding natural and / or synthetic binders and other substances. For the preparation of wood material, cutting procedures are used to obtain wood particles. Examples of wood particles are wood flakes, wood strands, slices of wood, wood shavings and shredded cuttings. Next, the wood particles are usually dried, glued with a composition (tail float) containing a binder and arranged in one or different layers (dispersion). Finally, the dispersed wood material is pressed under pressure and temperature action forming the desired wood chip material.

The expert distinguishes between wood chip materials and wood fiber materials. The wood chip materials and the fiber materials in the manner as well as their manufacturing processes differ fundamentally from one another. The wood fiber materials contain as a main component a fiber material obtained from wood. Said fiber material is obtained by vaporization or firing (for example, in a preliminary boiler or kettle) of wood material and by its chemical or mechanical decomposition (for example, in a refiner) to obtain individual fibers, bundles of fibers or fragments of fibers. On the contrary, the wood chip materials contain as a main component chip material, that is, wood chips. The chip material is obtained by the mere crushing of wood material. No treatment is carried out by vaporization, cooking or chemical or mechanical decomposition as in defibration.

The binders for the manufacture of wood chip materials may have one or more components. Usually, binders for the manufacture of wood chip materials are composed of or contain synthetic resins.

The synthetic resins are basically known by the expert. Synthetic resins are described for example in "Rompps Chemie-Lexikon", 7th edition, Frankh'sche Verlagshandlung Stuttgart, 1973, page 1893. An important group of synthetic resins are the condensed resins. These are hardened by condensation reactions, in which water is often dissociated. Among the condensed resins are, for example, phenol-formaldehyde resins and aminoplast resins.

Aminoplast resins have proved to be especially suitable for the practice in relation to the manufacture of wood chip materials. Usually, a wood chip material contains at least one aminoplast resin as a binder. Aminoplast resins are commonly used in wood chip materials to bond lignocellulose-containing wood particles or particles to one another. For this, an individual aminoplast resin or a mixture of different aminoplast resins can be used.

The aminoplast resins are known to the person skilled in the art and are described, for example, in "Ullmanns Enzyklopadie der technischen Chemie", 4th edition, volume 7. page 403 et seq. The aminoplast resins can be obtained by the condensation of a component containing amino, imino or amide groups, with a carbonyl compound. Common starting materials for aminoplast resins are, for example, urea and / or melanin (as a component containing amino groups) and formaldehyde (as a carbonyl compound). In the latter case, the amino-containing component is generally precondensed in a first step with the carbonyl compound to a certain degree. According to whether in the first step, for example, only melanin is used or only Urea as a component containing amino groups, one obtains a so-called melanin resin or a urea resin. Melamine and / or urea resins of this type can especially be the main components of aminoplast resins. In a second step which is often also referred to as hardening, the aminoplast resin can then be continuously crosslinked. The resins formed by urea and formaldehyde are also referred to as urea-formaldehyde resins. The resins formed by melanin and formaldehyde are also referred to as melanin-formaldehyde resin.

When we speak of aminoplast resins here or elsewhere, it also refers to aminoplast resin compositions. Aminoplast resins and / or aminoplast resin compositions may also contain water.

The curing of synthetic resins, in particular of aminoplast resins, can be carried out, for example, by the addition of acid catalysts. Conventional hardeners are conventionally used for this purpose. Hardeners and their reaction to initiate hardening reactions are described, for example, in "Holzwerkstoffe und Leime: Technologie und Einflussfaktoren" by M. Dunky and P. Niemz, Springer-Verlag Verlag, 2013, pages 265 to 270. Basically, typical hardeners for aminoplast resins they have in common that they contain, are composed of or can release said acid. Said acid catalyzes or initiates the hardening reaction. Examples of conventional hardeners are strong organic acids, inorganic acids such as sulfuric acid and phosphoric acid, salts that react acid in water such as aluminum chloride or aluminum nitrate (also known as acid salts), salts which by reaction with components of the synthetic resin, preferably with formaldehyde, generate an acid (also called acid-generating salts) such as ammonium phosphate, ammonium nitrate, ammonium sulfate and ammonium chloride, and mixtures of the substances mentioned above.

In case of human or animal exposure, formaldehyde can be harmful to health and cause allergies, irritations of the skin, respiratory tract or eyes. In case of chronic exposure, it can even be carcinogenic. Therefore, it is desirable to manufacture wood chip materials with a reduced formaldehyde content. This is especially important with regard to the use of wood chip materials for the manufacture of furniture or as a floor covering.

JPS60210406A discloses a process for the manufacture of a floor covering containing lignocellulose, in which dry mixed cellulose, fine aggregates, cork material in the form of powder and urea resin are used.

DE102004010796A1 refers to a process for reducing the emission of formaldehyde and other volatile organic compounds from plates of lignocellulose-containing material, in which the material is defibrated by thermomechanical decomposition to form particles and / or fibers, glued, it forms forming mats and is pressed forming a finished plate, the degradation products of the lignocellulosic material, caused by the decomposition, being partially or completely eliminated by leaching.

For hardening especially aminoplast resins, various hardeners are known to the person skilled in the art: WO02 / 068178A2 describes a method for gluing products laminated with an aminoplast resin, in which a hardener is used which contains an acid salt and / or a salt which generates acid, as well as a polymer dispersion.

WO2005 / 030895A1 discloses binder systems which, in addition to aminoplast resins and N-functionalized copolymers, also contain at least one acid, an acid salt and / or a salt that generates acid. WO2007 / 012615A1 discloses a hardener composition for aminoplast resins containing an acid, an acid salt and / or a salt generating acid and an aminoplast resin dispersion with a residual activity less than or equal to 100 J / g.

The disadvantage of the curing compositions in the state of the art is that the curing of the aminoplast resin using strong acids as a hardener is difficult to control, since the hardening can already begin when the acid is added.

To avoid this unwanted early hardening, the so-called preliminary hardening application procedure has been proposed in the prior art, in which the acid is first applied to the previous or intermediate product of the wood chip material. and, only afterwards, the gluing is carried out with a synthetic resin. However, economic expense here is disadvantageous by the additional process steps.

In addition, strong acids contribute to a greater extent to the unwanted hydrolysis of the cast joint. Frequently, additional buffer systems have to be used to reduce these disadvantages, which however can lead to insufficient hardening of the resin. The same is true for the use of acid salts in which hardening can also begin with the addition of the acid salts. Another disadvantage of salts which generate acid consists in that these salts usually require free formaldehyde to form the corresponding strong acid which then contributes to the hardening of the resin. Therefore, binder compositions (tail fleets) containing hardener systems based on acid-generating salts require a greater part of formaldehyde. This formaldehyde is usually not permanently bound and can be slowly released again after the manufacturing process is completed. Therefore, these hardener compositions are not optimal for the manufacture of wood chip materials with a reduced formaldehyde content.

In addition, the use of ammonium salts can be problematic also under ecological, economic and safety aspects. On the one hand, ammonium compounds constitute before, during and after the manufacture a source of potential emission for ammonia and, on the other hand, also the use of ammonium chloride has to be assessed as critical with a view to recycling and thermal use final. In addition, ammonium nitrate poses a risk during storage, as it is combustion and explosive.

Another critical aspect is that in the case of the use of ammonium compounds or the direct addition of acid, after the manufacture of the wood chip material, acid can still be formed or free strong acid remains in the wood chip material. This acid can lead to the hydrolysis of the casting, which can adversely affect the stability and swelling properties of the wood chip material.

Starting from the state of the art described above and from its disadvantages, the invention had the objective of providing a method employing an alternative, improved hardening system. Especially, the invention had the objective of providing a process that allows to manufacture wood chip materials with a reduced formaldehyde content.

This object is achieved according to the invention by a method according to claim 1 and the use according to claim 20.

Advantageous embodiments of the invention are described in the dependent claims and are hereinafter explained in detail as the general idea of the invention.

The method according to the invention for the manufacture of a wood chip material comprising the steps:

a) the provision of a first material containing lignocellulose in the form of wood particles; b) gluing the first lignocellulose-containing material with a composition comprising at least one aminoplast resin and at least one first hardener, the first hardener having been obtained by the hydrothermal and mechanical decomposition of a second lignocellulose-containing material, and the second hardener proceeding material containing lignocellulose from another raw material than the first material containing lignocellulose;

c) the pressing forming a material of wood chips.

Optionally, before, after and / or between steps a) to c) additional procedural steps can be performed. Optional steps may be, for example, preheating in a preheating vessel, grinding, storage, mixing, addition of additional substances, dispersion or drying of the material used or obtained in steps a) to c).

Surprisingly, it was found that by using a hardener of a material containing lignocellulose, hydrothermally and mechanically decomposed, the aforementioned problems known from the prior art can be avoided or reduced to a greater extent.

Since the aminoplast resin used in the process according to the invention can also contain additional hardeners, the hardener obtained by the hydrothermal and mechanical decomposition of lignocellulose-containing material is referred to herein as the "first hardener".

It is advantageous that the use of the first hardener can be integrated in a simple manner in processes customary in the wood industry for the manufacture of wood chip materials. No complicated intermediate steps or procedure interruptions are required.

Also, it is advantageous that the first hardener which is used according to the invention can be obtained economically and is readily available. It can be obtained by the hydrothermal and mechanical decomposition of lignocellulose-containing material. In a preferred embodiment of the invention, the first hardener is obtained from biomass containing lignocellulose. When we talk about biomass here, it refers to the plants, parts of plants, fruits and mixtures of these, more diverse, especially also of waste from agricultural plants or the wood industry. The use of this biomass for the manufacture of the first hardener is therefore a very important ecological advantage, since biomass is a renewable raw material. A special embodiment of the invention makes it possible to use waste products from the first hardener plants that already or only are not suitable for the final use. In total, a better cascade utilization of vegetable raw materials can be achieved by the process according to the invention.

Another practical and economic advantage of the first hardener is that it can be manufactured in a particularly simple and inexpensive manner. The processes for the hydrothermal and mechanical decomposition of lignocellulose-containing material are known to the person skilled in the art, for example, for the manufacture of fiber plates. It is also important for practice that the first hardener can be added particularly easily to the binder composition (tail float) and is compatible with it. This is not possible, for example, in the case of the use of strong acids sometimes practiced in the state of the art, such as are used, for example, in the preliminary hardening application process.

In addition, the method according to the invention allows a reduced use of the chemical substances mentioned above. By using the first hardener according to the invention according to the invention, the need for free formaldehyde and / or the amount of conventional hardeners such as, for example, acid-generating salts, can be markedly reduced. Therefore, the first hardener constitutes an alternative and / or a complement to the conventional hardeners described at the beginning.

Without wanting to be limited to a specific scientific theory, this surprising effect of the first hardener seems to be explained because during hydrothermal and mechanical decomposition one or several acids are released. This at least one acid seems to contribute to the hardening of the resin.

In the at least one acid released during hydrothermal and mechanical decomposition, it also appears to be a slightly volatile acid. Therefore, this acid does not remain or remains only for a short time in the casting of the finished wood chip material. Due to this type of short residence of the acid, a hydrolysis of the joint cast by said acid can be largely avoided. When we talk about acid here, it can refer to an individual acid or mixtures of different acids.

Important characteristic quantities for wood chip materials are swelling, transverse tensile strength and water absorption. Surprisingly, in practical experiments it was found that these characteristic magnitudes are improved in wood chip materials that were manufactured by the process according to the invention. In particular, by using the first hardener according to the invention which can be obtained by hydrothermal and mechanical decomposition, it is possible to reduce the amount of conventional hardener and, in part, even to dispense with it, without causing a worsening of said characteristic magnitudes. For example, the transverse tensile strength of wood chip materials is improved. In addition, swelling and / or water absorption of wood chip materials is significantly reduced.

When we speak of "lignocellulose-containing material", it refers to a plant material containing lignocellulose Lignocellulose in the sense of the invention contains cellulose and / or hemicellulose as well as lignin. "Cellulose" is an unbranched polysaccharide which It consists of several hundred and ten thousand units of cellobiose. These cellobiose units in turn are composed of two glucose molecules that are linked through a 6-1,4-glycosidic bond.

"Hemicellulose" is a collective designation for different components of plant cell walls.Hemicelluloses are branched polysaccharides with a shorter chain length - usually less than 500 units of sugar - which are formed by several sugar monomers.Hemicellulose is substantially formed by different sugar monomers such as glucose, xylose, arabinose, galactose and mannose, the sugars may be substituted by acetyl and methyl groups, they have a random amorphous structure and are hydrolyzed well.Xylose or arabinose are mainly composed of monomers of sugar with five carbon atoms (pentoses) Mannose or galactose are composed mainly of sugar monomers with six carbon atoms (hexoses).

"Lignins" are amorphous, branched amorphous macromolecules of an irregular nature that exist in nature as a component of cell walls where they cause lignification of the cell.They are formed of substituted phenylpropanol units, have a lipophilic character and are insoluble at room temperature. neutral solvents such as water The lignin precursor substances are, for example, p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol, The molar masses of lignin are usually between 10,000 and 20,000 g / mol.

"Hydrolysis" in the sense of the invention can refer in particular to the dissociation of a (bio) chemical compound by reaction with water, during which, in particular, a hydrogen atom can be formally emitted to a dissociated part and the remaining hydroxyl radical it can be issued to the other dissociated party.

When we speak of "wood chip material", according to the invention, this means different materials based on chips that are made of wood or contain wood. (chip plates in the widest sense), designates a group of products in the field of wood materials that are manufactured by means of heat and pressure from wood particles and at least one binder. Another group of products in the field of wood chip materials that are not covered by the term "wood chip material" as used herein are wood fiber materials, the latter being fiber plates as per For example, medium density fiberboard (MDF) and high density fiberboard (HDF), unlike wood chip materials, for the manufacture of fiberboard, the wood used is broken down to obtain wood fibers. of fibers or fiber fragments For the expert, wood chip materials and wood fiber materials are two categories of fundamentally different materials to be differentiated.

Basically, the expert knows different wood chip materials. Examples of these are chip plates, flat pressed plates, monolayer plates, multilayer plates, light flat pressed plates, extruded plates, extruded tubular plates (ET - "Extruded Tubular"), solid extruded plates (ES - "Extruded Solid") , flat decorative plates pressed with synthetic material (MFB - "Melanin Faced Board"), shaped pieces of wood chips or plates of oriented chips (OSB - "Oriented Strand Board"). The classification of the chip plates can be carried out in accordance with DIN EN 312, according to which the chip plates can be differentiated in terms of their strength and resistance to moisture. OSB sheets can be classified according to their use in accordance with EN 300. Wood chip materials of this type can be processed, for example, into laminates, floor coverings, worktops, tabletops, pallets and / or shaped wood pieces. . Wood chip materials, their manufacture and their requirements are also described in "Taschenbuch der Holztechnik", A. Wagenführ, F. Scholz, Carl Hanser Verlag. 2nd edition 2012, on pages 143 to 146.

According to one embodiment of the invention, the wood chip material is a plate of wood chip material. Preferably, the wood chip material is a plate of chips or OSB plates. Practical experiments have shown that the process according to the invention as well as the embodiments described above are particularly suitable for the manufacture of pressed wood chip materials, especially for the manufacture of chips plates and OSB plates.

Preferably, the wood chip material or its previous or intermediate product is substantially composed of lignocellulose and binder-containing material. "Substantially" here means 90% by weight, 95% by weight, 99% by weight or 99.9% by weight, based on the total weight of the wood chip material, respectively.

However, it is also possible that the wood chip material, or its previous or intermediate product, contains additional substances. For example, wetting agents and / or separators can be added for an improved pressing process. In addition, fungistatic or flame retardant agents can be added. In this way, wood chip materials containing lignocellulose can meet special requirements. These types of requirements have already been mentioned above and are known to the expert. In particular, this type of additional substances can be added to the process according to the invention before, during and / or after one of steps a) to c).

Step a) of the process according to the invention provides for the provision of wood particles. When we speak of wood particles here, it refers to any type of wood particles that can be used for the manufacture of wood chip materials. The wood particles can be any type of grinding products of lignocellulose-containing material. The wood particles as used herein do not include wood fibers.

Since the hardener used according to the invention also contains lignocellulose, the wood particles used in step a) are designated here as the "first lignocellulose-containing material". To differentiate them, the material used for the manufacture of the hardener is designated as "second material containing lignocellulose". The first lignocellulose-containing material differs from the second lignocellulose-containing material as described below.

For the production of wood chip materials according to the process according to the invention and its embodiments, a first lignocellulose-containing material present in the form of wood particles is used in step a). Depending on the type of wood chip material, the first lignocellulose-containing material can be produced by grinding lignocellulose-containing materials. According to the invention, the first lignocellulose-containing material is made available in the form of wood particles, that is to say it can contain or be composed of wood particles. The wood particles as used here may contain wood or be composed of wood. Examples of wood particles are fine-particle wood materials, wood chips, wood strands, wood chips, wood flakes and shredded cuttings. Usually, wood particles for wood chip materials are obtained by cutting processes. In an optional step, the wood particles can be dried or stored in an intermediate way before the next processing. In addition, additional substances may be added to the first and / or the second material containing lignocellulose.

Basically, the skilled person knows different methods for manufacturing wood chip materials by pressing. According to one embodiment of the invention, the wood particles glued in step b) are pressed in step c) to form a wood chip material. Preferably, in step c) it is a hot pressing. Optimal results can be achieved if the compression factor during hot pressing is between 2 and 10 s / mm, preferably between 3 and 6 s / mm. By compression factor is meant here, in particular, the residence time in press of the wood chip material containing lignocellulose in seconds per millimeter of thickness or thickness of the wood chip material containing lignocellulose, finished pressing.

Suitable temperatures for the pressing in step c) of the process according to the invention or one of its embodiments are temperatures of 150 ° C to 250 ° C, preferably 160 ° C to 240 ° C, particularly preferably 180 ° C. C at 230 ° C. At temperatures within these ranges, the process can be carried out particularly cost-effectively.

For economic and process engineering reasons, it has turned out to be advantageous if a specific compression pressure (active pressure on the surface of the plate) of 50 to 300 N / cm2 is used during the pressing. This type of pressure guarantees a particularly good mutual adhesion of the lignocellulose-containing particles. In addition, with a compression pressure of this type, a great solidity of wood chip materials containing lignocellulose can be achieved.

Since the process according to the invention is a process for the manufacture of wood chip materials from wood particles (here, designated as the "first lignocellulose-containing material") used in step a), this procedure does not include no defibration, vaporization, cooking or chemical and / or mechanical decomposition (for example, in a refiner) of the first lignocellulose-containing material, as practiced for example in the manufacture of wood fiber plates.

In step b) of the process according to the invention, the first lignocellulose-containing material is glued with a composition comprising at least one aminoplast resin and at least one first hardener. When referring to "gluing" here, it refers to the total or partial wetting with a composition containing a binder ("binder-containing composition"). This type of compositions are also known by the person skilled in the art as "tail floats." According to the invention, the binder is an aminoplastic resin, and especially the homogeneous distribution of the binder-containing composition on the wood particles can also be entangled. Application of the binder-containing composition can be carried out, for example, by impregnation or spraying.

The method according to the invention comprises in step b) the gluing of wood particles with a composition comprising at least one aminoplast resin and at least one first hardener. This can be done in various ways. In particular, the hardener can be added to the aminoplast resin prior to and / or during gluing to manufacture the composition. According to an embodiment of the process according to the invention, a pre-blended aminoplast resin mixture and the first hardener are used as the composition for gluing the wood particles and applied to the wood particles. According to this embodiment of the process, therefore, the wood particles are glued with a composition containing an aminoplast resin and a first hardener, applying on the wood particles a mixture of aminoplast resin and the first hardener, previously prepared.

However, the process according to the invention also comprises embodiments in which the hardener is added to the aminoplast resin only during gluing and, therefore, the composition originates only in situ during gluing. This can be done in particular in such a way that during the gluing of the wood particles, the aminoplast resin and the first hardener are applied to the wood particles separately from one another, possibly with additional additives and binders. During this, the aminoplast resin and the hardener are mixed, so that a composition is formed which "contains" an aminoplast resin and a first hardener, for example, the aminoplast resin can be applied to the wood particles in a first step. In a second step, the first hardener, vice versa, it is also possible to apply the first hardener to the wood particles in a first step, and then to the aminoplast resin in a second step.A simultaneous application of the aminoplast resin is also possible. the first hardener by means of two separate application devices, such as for example nozzles, on wood particles Accordingly, another embodiment of the method provides that the wood particles are glued with a composition containing an aminoplast resin and a first hardener , in such a way that the aminoplast resin and the first hardener are applied on the wood particles separately.

The amount of the binder used during gluing is preferably between 0.1 and 20% by weight, in particular between 1 and 16% by weight, more preferably between 4 and 14% by weight, based on the dry weight of wood (solid resin / atro). For many applications it is particularly suitable for practice, if the binder is used in an amount of 0.1 to 15% by weight with respect to the dry weight of wood (solid resin / atro).

Basically, the process according to the invention or one of its embodiments are suitable for a multitude of combinations of binders and wood particles. According to the invention, at least one aminoplast resin is used as a binder. Alternatively or additionally, other synthetic resins, especially phenoplastics, vinyl acetates, isocyanates, epoxy resins and / or acrylic resins can also be used in the process according to the invention. In one embodiment of the invention, the binder is composed of an aminoplast resin and one or more hardeners. Examples of aminoplast resins are ureaformaldehyde resins (UF), urea-formaldehyde resins reinforced with melanin (MUF), melanin-urea-phenolformaldehyde resins (MUPF) or mixtures thereof. In practice, particularly good results are achieved with urea-formaldehyde (UF) resins, urea-formaldehyde resins reinforced with melanin (MUF) or mixtures thereof.

Preferably, the aminoplast resin can be obtained by condensation of a component containing amino groups with a carbonyl compound. The carbonyl compound is preferably formaldehyde. The component containing amino groups is preferably melanin and / or urea. Especially preferably, the aminoplast resin is a melamine resin or a urea resin, especially a melamine-formaldehyde resin or a urea-formaldehyde resin or a urea-formaldehyde resin.

The composition (tail float) used in the process according to the invention also contains at least one first hardener. Advantageously, the binder contains 0.1 to 15% by weight of the first hardener, especially 0.5 to 10% by weight with respect to the solid resin part of the aminoplast resin.

The term "hardener" as used herein is a technical term known to the person skilled in the manufacture of wood chip materials Hardeners are catalysts that catalyze, that is, promote or initiate a hardening or crosslinking reaction. , without spending themselves during it As the expert knows, catalysts are substances that increase the speed of reactions by reducing the activation energy of a chemical reaction, without spending themselves during it.The hardening of aminoplast resins is carried out by acid catalysis The acid that acts as a hardener here initiates and advances the hardening or crosslinking reaction without using it during this process Hardeners, therefore, differ from the educts of the crosslinking reaction of aminoplast resins , which during the hardening of aminoplast resins react with each other and therefore Likewise, the hardeners are also differentiated from additives, for example, diluents such as lignin, which through functional groups are capable of being incorporated by polymerization into the aminoplast resin. This type of additives that can be incorporated by polymerization during the hardening of the aminoplast resin and thus can finish reacting and wear out are not included in the term "hardener" as used herein.

The first hardener used according to the invention is based on a lignocellulose-containing material. It is obtained by the hydrothermal and mechanical decomposition of such lignocellulose-containing material. According to one embodiment, therefore, the first hardener used according to the invention contains hydrothermally and mechanically decomposed lignocellulose-containing material or consists of it.

The hardener which is used according to the invention is obtained from a second lignocellulose-containing material which differs from the first lignocellulose-containing material described above, used in step a). This difference consists especially in the origin and / or the raw materials on which it is based. According to the invention, it is especially provided that the second material containing lignocellulose comes from another raw material than the first material containing lignocellulose. The first and second material containing lignocellulose can represent different raw materials or have been manufactured or obtained from different raw materials. According to one embodiment, the difference in the raw materials consists of the plant species or the composition of plant species from which the two lignocellulose-containing materials are obtained. According to another embodiment, the difference in the raw materials consists of the plant genus or the composition of plant genera from which the two lignocellulose-containing materials are obtained. The terms vegetable species and plant genus are understood according to the usual botanical definition (taxon and genus).

The first lignocellulose-containing material is made available according to the invention in the form of wood particles, that is to say that at least one raw material from which the first lignocellulose-containing material originates is wood. The second material containing lignocellulose may have been obtained from another species so that it was used as a raw material for the first material containing lignocellulose. Preferably, however, the raw materials for the first and second lignocellulose-containing material differ in such a way that the second material containing lignocellulose comes from a raw material other than wood, especially tree wood.

In a preferred embodiment of the invention, the second lignocellulose-containing material is selected from the group consisting of annular plants, useful plants, herbs, leaves, cereals, their components and wastes or mixtures thereof. Useful plant is understood to be straw, wheat, rye, barley, oats, millet, corn, miscanthus, rice, its components, its waste and / or mixtures thereof. When we speak here of "annual plants", it refers to plants and / or their components that contain lignocellulose and that from the germination of their seed to the pollination of their flower and the maturation of the new seed take a period of vegetation and they die after the maturation of the new seed. In an especially preferred embodiment, one or more of these selected second materials containing lignocellulose are subjected to a hydrothermal and mechanical decomposition. This hydrothermally and mechanically decomposed material can then be used as the first hardener.

The use of lignocellulose-containing materials, described above, for the manufacture of the first hardener has turned out to be advantageous in terms of cost-effectiveness. The mentioned plants are easy and quick to grow and can be easily processed and in a few procedural steps. For example, through the processing of plant waste not only guarantees an economic raw material, but also a better cascade use of plant raw materials. On the contrary, in the case of using wood, especially tree wood, as a raw material for the manufacture of the first hardener, the much longer cultivation times, the significantly higher labor investment and the costs of wood processing would be disadvantageous. Therefore, according to the invention, it has turned out to be advantageous if the "second" material containing lignocellulose, used for the manufacture of the hardener used according to the invention, differs from the so-called "first" material containing lignocellulose, used in step a) of the process according to the invention for the manufacture of wood chip material.

For these reasons, according to a special embodiment of the invention, it is provided that the second material containing lignocellulose does not contain wood, especially tree wood, nor does it come from such raw materials. According to the invention, the raw materials mentioned above for the second lignocellulose-containing material (see claims 14 and 15) are not included in the generic term "wood".

In one embodiment of the invention, the second lignocellulose-containing material can be used in non-crushed form for hydrothermal and mechanical decomposition. In another embodiment of the invention, the second lignocellulose-containing material can also be pre-crushed for hydrothermal and mechanical decomposition. Preferably, it is pre-crushed dry. The second material containing lignocellulose, crushed, can have a mean particle size - determined according to the mesh width of the sieve - from 20 | jm to 20 mm, from 0.05 | jm to 1 mm or from 0.4 | jm at 0.4 mm.

In the "average particle sizes" indicated here, these are average sieve diameters determined by the fact that the particles pass through a defined mesh width of a sieve The expert basically knows methods for determining particle sizes For example, the sieving analysis according to DIN61165 For the analysis of the average sieving diameter, for example, a sieve system with mesh widths can be chosen, which decreases from top to bottom.Then, during the sieving process, each sieve is left that part that has passed through the upper sieve, but has not passed through the sieve in question, the different parts can be weighed and represented in percentage form in the form of a particle distribution, from which the diameter can also be calculated screening medium according to DIN66165. For particle sizes or fractions of small particles, it is possible to resort to microscopic procedures. cos for the determination of particle size.

Preferably, the second grinded lignocellulose-containing material has a particle size distribution with which at least 70, 80, 90 or 95% by weight of the material has a sieve diameter of 20 jm to 20 mm, of 0, 05 jm to 1 mm or 0.1 jm to 0.4 mm, determined by the mesh width of the screen. This particle size distribution may exist before or after mechanical decomposition. Preferably, this particle size distribution refers to the material that has already been mechanically ground and is only subjected to a hydrothermal and mechanical decomposition.

In one embodiment, the particle size or the average particle size can be determined in such a way that the particles of the second lignocellulose-containing material pass through a sieve with a mesh width of 20 mm, preferably 1 mm, in a form especially preferably 0.4 mm and particularly preferably 0.2 mm. For practice, this means that according to one embodiment of the invention, fractions of particles resulting from particles passing through these mesh widths can be used. The average particle size is determined in this embodiment by a "maximum size" of the particles by the mesh widths defined above.These particle sizes may exist before or after the hydrothermal and mechanical decomposition. The particles refer to the material that was already mechanically ground and is only subjected to a hydrothermal and mechanical decomposition.

According to another embodiment of the invention, the second grinded lignocellulose-containing material has a particle size distribution with which at least 70, 80, 90 or 95% by weight of the material has a screening diameter of less than 20. mm, preferably less than 1 mm, less than 0.4 mm or less than 0.2 mm, determined respectively by passing through a screen with a corresponding mesh width.

When the term "dry weight" is used here, it refers to the content of dry mass.The content of dry mass is that part of a substance that remains after deducting the mass of water contained.This means that the dry mass content and the The water content of a substance is complemented 100% In one embodiment of the invention, the first hardener can have a dry weight of 5 to 25% by weight, especially 10 to 20% by weight with respect to total weight of the material.

During the hydrothermal and mechanical decomposition of the second material containing lignocellulose, acid can be liberated. According to a preferred embodiment, the first hardener contains in step b) an acid that was released by the hydrothermal and mechanical decomposition of the second lignocellulose-containing material. This is advantageous in particular because the second material containing lignocellulose, hydrothermally and mechanically decomposed, directly contains the acid which can act as a catalyst during the hardening reaction (as described above) and does not have to be released first. In an embodiment of the invention, the second lignocellulose-containing material releases during hydrothermal and mechanical decomposition at least one acid, in the presence of water and / or thermal action. Surprisingly, it was found that weak and / or volatile acids are preferably released during hydrothermal and mechanical decomposition. In a preferred embodiment of the invention, formic acid and / or acetic acid are released during hydrothermal and mechanical decomposition. Since formic acid and / or acetic acid are weak acids, the disadvantages described above for strong acids can be avoided to a large extent.

"Hydrothermal" as used herein means that the decomposition is carried out under the action of water and elevated temperature. Water can come from the same materials used or added. Preferably, water is added, especially in the form of water vapor. According to a preferred embodiment of the invention, the decomposition mentioned in step b) is a decomposition simultaneously hydrothermal and mechanical.

Without wanting to be linked to a scientific theory, the release of acid seems to be due to the good hydrolyzing capacity of hemicellulose. Comparative experiments with microcrystalline cellulose that was subjected to hydrothermal and mechanical decomposition conditions did not lead to acid release. Basically, the p-1,4-glycosidic bonds of the glucose molecule are very stable. Therefore, for the hydrolysis of cellulose it requires drastic conditions such as for example strongly acidic or strongly alkaline conditions or special enzymes. One reason that microcrystalline cellulose does not release acid during hydrothermal and mechanical decomposition could be that this decomposition is not sufficiently acidic or alkaline.

In this way, it also seems to be possible to explain why the second lignocellulose-containing material mentioned above, for example tree wood, is much more suitable for the manufacture of the first hardener. One reason for this could be that the second lignocellulose-containing material used according to the invention, especially the plants mentioned above, have a greater average part of hemicellulose than, for example, tree wood, especially coniferous wood.

According to one embodiment of the invention, the release of the acid contributes to the hardening of the resin. This is the case especially if the resin can be hardened by acid catalysis. Among the resins curable by acid catalysis are aminoplast resins. According to one embodiment of the invention, the acid liberated during the hydrothermal and mechanical decomposition contributes to the hardening of the aminoplast resin contained in the binder-containing composition.

In one embodiment of the invention, the acid liberated during hydrothermal and mechanical decomposition has a molecular weight of 40 g / mol to 500 g / mol, especially from 40 g / mol to 250 g / mol. According to another embodiment, the acid is a Bronsted acid with a pK ^a of 2 to 8, especially of 3 to 6. Preferably, the acid is a carboxylic acid with a chain length of 1 to 5 carbon atoms. Examples of carboxylic acids are formic acid, acetic acid, propanoic acid, butyric acid, pentanoic acid and derivatives thereof. Examples and characteristics of Bronsted acids are described for example in "Basiswissen der Chemie", C. Mortimer, Thieme, 7th edition, 2001, pages 281 to 290. By pK ^a is meant the negative decadic logarithm of the acidity constant K ^a under standard conditions (see also "Organic Chemistry", Jonathan Clayden, Nick Greeves, Stuart Warren, Oxford OUP, 2012, pages 163 to 181). The smaller the pK ^a value, the stronger the acid. If an acid has several dissociation steps (for example, H ² SO ⁴ : pK ^at 1st stage: -3, 2nd stage: 1.92), here, the pK ^a value refers to the pK ^a value of the 1st stage of dissociation. The pK ^a values of some important Bronsted acids are found in the following table.

In one embodiment of the invention, the carboxylic acid is a weak acid. When we speak of weak acids here or elsewhere, it means that the pKa is equal to or greater than 3. With a pKa of less than 3 of Bronsted's acid, the binder can be attacked by the acid and hydrolyzed at least in part for this.

Practical experiments with the first hardener to be used according to the invention have resulted in a markedly reduced hydrolysis of the cast joint, if the acid that is released during hydrothermal and mechanical decomposition and that can contribute to the hardening of the aminoplast resin is a weak acid . One reason for this could be that because of the low acidity of the weak acids, the hydrolysis is not as pronounced as is the case in acids from conventional hardeners and / or strong acids. Conventional hardeners, such as, for example, ammonium salts, are still capable, even after finishing the wood chip material, of releasing additional acids which can diffuse into the cast joint and hydrolyze it.

In another embodiment of the invention, the carboxylic acid is a volatile acid. Examples of volatile acids are formic acid or acetic acid. The volatility of the acid can contribute to further improving the stability of the casting. One reason for this could be that a volatile acid remains for a shorter time in the cast joint than acids from conventional hardeners. By this shorter residence time, undesired hydrolysis of the casting can be reduced or even prevented.

The first hardener can be obtained by hydrothermal and mechanical decomposition. Suitable temperatures for the hydrothermal and mechanical decomposition of the second lignocellulose-containing material are temperatures of 120 to 180 ° C, preferably 130 to 170 ° C and especially preferably 140 to 160 ° C.

For reasons of the process technique it is particularly suitable for practice if the hydrothermal and mechanical decomposition the second lignocellulose-containing material is carried out at a pressure of 3 to 10 bar, especially at between 4 and 8 bar.

In one embodiment of the invention, the duration of hydrothermal and mechanical decomposition is from 2 seconds to 40 minutes, especially from 5 seconds to 30 minutes.

In another embodiment of the invention, the hydrothermal and mechanical decomposition can be carried out in a preheater tank, a boiler and / or a refiner. Preferably, the hydrothermal and mechanical decomposition is carried out in a boiler and / or a pressure reactor. Alternatively or additionally, the hydrothermal and mechanical decomposition is preferably carried out in a refiner. In addition, hydrothermal and mechanical decomposition may comprise the following steps:

(i) the hydrothermal decomposition of the second material containing lignocellulose in a boiler and / or pressure reactor,

(ii) mechanical decomposition by grinding the second lignocellulose-containing material from step (i) in a refiner.

The terms kettle, pressurized reactor and refiner are known to the expert active in the lumber industry. By "kettle" is meant in particular a device suitable for the hydrothermal decomposition of the second material containing lignocellulose. The "pressure reactor" is any reaction tank constituting a sealed bounded space in which a pressure can be established and which is suitable for carrying out the hydrothermal decomposition of the second lignocellulose-containing material. By "refiner", the skilled person understands a device for crushing or defibring wood, especially under the action of pressure. Examples of refiners commonly used in practice are the Southerland refiners with a hollow shaft and with a mobile grinding disc, the Fritz refiners with 10 grinding discs, the Calfin refiners and the hydro-refiners.

The hydrothermal decomposition in step (i) can be carried out at a temperature of 120 to 180 ° C, especially at 140 to 160 ° C. Suitable pressures for hydrothermal decomposition are between 3 and 8 bar, especially between 4 and 6 bar. The duration of the decomposition can be between 5 and 40 minutes. A decomposition time of 30 min has been found to be advantageous. Good results are achieved if step (i) is carried out in the presence of water. The use of water vapor has proved especially suitable for practice.

The mechanical decomposition in step (ii) is carried out in a refiner. Particularly suitable process temperatures are in a range from 140 to 180 ° C, in particular from 150 to 160 ° C and a pressure from 1 to 8 bar, especially from 4 to 6 bar. The duration of the mechanical decomposition can be between 2 seconds and 5 minutes, especially between 5 seconds and 3 minutes. In another embodiment of the invention, step (ii) can be carried out under the presence of water, especially water vapor.

In another embodiment of the invention, optional additional process steps may be carried out before, after or between steps (i) and (ii). The optional steps can be preheating in a preheating tank, grinding, storage, mixing, dispersing, adding additional substances or drying the lignocellulose-containing material or a mixture containing the lignocellulose-containing material of the Steps (i) and / or (ii).

In practice, it has turned out to be advantageous if the binder-containing composition contains, in addition to the first hardener which is used according to the invention, a second hardener. The second hardener may be a conventional hardener described above, especially an ammonium salt. Examples of suitable ammonium salts are ammonium nitrate, ammonium phosphate, ammonium chloride and ammonium sulfate. Under reaction with formaldehyde, these ammonium salts form their corresponding acid which, as an acid catalyst, contributes to the hardening of the resin. Examples of these are nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid.

It has been shown that the first hardener used according to the invention is especially compatible with aminoplast resins and with the conventional hardeners commonly used therein. In addition, binder compositions containing an aminoplast resin, a first hardener according to the invention and a second hardener have proved to be very stable.

In another embodiment of the process according to the invention, the binder-containing composition contains from 0.1 to 4% by weight of ammonium salt, especially from 0.5 to 3.0% by weight, based on the resin solid resin. In a preferred embodiment of the process, the ammonium salt is ammonium nitrate and the resin is an aminoplast resin. It is particularly advantageous if the part of the second conventional hardener can be reduced by using the first hardener. In a particularly preferred embodiment of the invention, it is possible to save up to half or more of the second hardener, if the second hardener is used in combination with the first hardener which is used according to the invention.

Basically, this also means that, for example, in comparison with the single use of ammonium salts as hardener for aminoplast resins, significantly less ammonium salt must be supplied to the process. Because of the reduced content of ammonium salt, therefore, less formaldehyde must also be supplied to the process. In this way, it is possible to obtain wood chip materials with a reduced formaldehyde content. The same is true for other conventional hardeners that have been described at the beginning.

The disclosure also relates to wood chip materials containing lignocellulose, which have been manufactured or can be obtained according to the process according to the invention or its embodiments, which have been described above. A wood chip material of this type can be used especially well for the manufacture of a laminate, a floor covering, a work board, a table top, a piece of furniture or a pallet.

Furthermore, the invention also relates to the use according to claim 20 of the first hardener according to the invention which was obtained by the hydrothermal and mechanical decomposition of a second lignocellulose-containing material, in a method according to the invention, described above, for the manufacture of wood chip materials. For the characteristics of use, what has been said above with respect to the characteristics of the method according to the invention or its embodiments is valid. In particular, according to a preferred embodiment of the use according to the invention, the first hardener releases an acid. In another embodiment of the use according to the invention, the first hardener releases acetic acid and / or formic acid.

The advantages of the process according to the invention which have already been mentioned above are also valid for the use according to the invention of the first hardener. In particular, by using the first hardener, the strength of conventional wood chip materials can be maintained or even improved, while at the same time reducing the amount of conventional hardeners. In addition, by using the first hardener, while reducing the amount of conventional hardeners at the same time, an improvement in swelling performance and / or water absorption can be achieved. One reason for this could be that the acid released during hydrothermal and mechanical decomposition is freely present and volatizes more rapidly than conventional hardeners. In this way, a neutral casting is formed which positively influences the characteristic dimensions described above of the wood chip material. In the following, the invention is described in detail by way of example with the aid of exemplary embodiments. Example 1

First, the manufacture of the first hardener is described. Straw was used as lignocellulose-containing material.

Variant 1:

In the first variant, the decomposition of the lignocellulose-containing material was performed in a discontinuous one-disk refiner (Sprout Waldron). For this, the refiner was filled with the material and steam (160 ° C) was introduced into the cyclone. The material remained for approximately 2 minutes in the refiner at 160 ° C and 6 bars, then the cyclone was opened and the material was evacuated through the auger and a 2.5 mm valve in approx. 5 minutes.

Variant 2:

In the second variant, the lignocellulose-containing material was previously ground dry in an Ecopulser (Krause Maschinenbau GmbH) and sieved (Retsch AS 200). Subsequently, the fraction of particles smaller than 0.6 mm was boiled in a pressure reactor (Büchiglasuster Cyclon 300) for approx. 30 min. at 160 ° C and 5 to 6 bars under dilution with water of about 1: 5.

Example 2

Experiments with plates were carried out in the following conditions:

Plate thickness: 14 mm

Density of destination: 600 kg / m3

Press factor: 9.3 s / mm

Press temperature: 200 ° C

Gluing degree: 8.0% by weight with respect to the total mass of the chip plate

First material containing lignocellulose: wood shavings

First hardener: the material obtained in example 1 (variant 1 or 2)

Second hardener: ammonium nitrate

Press: Siempelkamp laboratory press

Several pressings were made with different dosages of the first hardener and / or the second hardener. As the first hardener, the lignocellulose-containing material prepared according to Example 1 was used in the dosages of 1, 3, 6 and 10% by weight of the solid substance with respect to the solid resin part (hereinafter% solid). As the second hardener, ammonium nitrate was used, in particular, in amounts of 1, 1.5, 2 and 3 % solid / RS.

The lignocellulose-containing material, prepared, was added to the tail fleet containing an aminoplast resin. After the pressing of the plates, the transverse tensile strength, the swelling and the water absorption were determined. For this, in the first place, specimens with the geometry of 50 x 50 x 14 mm were cut out. Each test piece was measured, before the test, by means of a digital thickness probe and the mass was determined and the density was calculated from it.

Transverse tensile strength

The determination of the transverse tensile strength was carried out according to EN 319. For this purpose, each specimen was glued, by means of a hot-melt adhesive, with two aluminum yokes on the upper and lower faces and, after cooling, they were separated from each other. traction in the test machine (Zwick Zmart.Pro) at a constant test speed of 1 mm / min. The force that caused the break in the center of the specimen was recorded and the resulting transverse tensile strength was calculated across the surface of the specimen [N / mm2].

Thickness swelling

The determination of the swelling thickness after 24 hours of storage in water was carried out according to DIN EN 317. For this, the test pieces were stored under water for 24 h at a water temperature of 20 ° C. Then, the increase in thickness was determined with respect to the starting thickness and the swelling of the percentage thickness was calculated.

Water absorption

The water absorption was determined in samples of the swelling thickness, ie also after 24 h of storage in water. For the calculation, the weight was measured after 24 h and then the water absorption was calculated according to the following formula:

Dough ^after - Dough ^before

Water Absorption [%] = ----------------------------------------- * 100

Dough ^before

The determined results were evaluated through Excel, Minitab or DesignExpert.

Next, the experiment results of reference plates containing only ammonium nitrate and plates containing the first hardener (decomposed material of example 1) and ammonium nitrate as the second hardener are represented. The plates were manufactured with the following hardener compositions:

The reference plates 1 and 2 were made without the addition of the first hardener. The plates object of experiment 1 to 3 were made with the first hardener of the variant 1 of example 1 and the plates under experiment 4 and 5 were made with the first hardener of the variant 2 of example 1.

The plates under experiment were respectively made at least in duplicate and the transverse tensile strength, swelling and absorption of water were determined. The measured values shown below are average values of at least two plates.

Result of the transverse tensile strength:

The transverse tensile strength was determined for the reference plates 1 and 2 and the plates object of experiment 1 to 3. The results are shown in diagram 1.

In diagram 1 it can be seen that the transverse tensile strength of the plates subjected to experiment 1 to 3 corresponded approximately to the transverse tensile strength of the reference plate 2. By the addition of the decomposed material in example 1, as the first hardener, the amount of ammonium nitrate was halved and nevertheless maintained the good transverse tensile strength.

Swelling result:

The swelling was determined on reference plate 2 and the plates under experiment 4 and 5. The results are shown in diagram 2.

The measurement yielded less swelling for the plates under experiment 4 and 5 despite the reduced content of ammonium nitrate.

Result of water absorption:

The water absorption was determined on reference plate 2 and the plate object of experiment 4. The results are shown in diagram 3.

It is demonstrated that using the first hardener it was possible to reduce the absorption of water, despite the reduced content of ammonium nitrate.

Claims (20)

1. Process for manufacturing a wood chip material, comprising the steps: a) the provision of a first material containing lignocellulose in the form of wood particles; b) gluing the first lignocellulose-containing material with a composition comprising at least one aminoplast resin and at least one first hardener and a second hardener, the first hardener having been obtained by the hydrothermal and mechanical decomposition of a second lignocellulose-containing material, and the second material containing lignocellulose from a raw material other than the first material containing lignocellulose; and the second hardener being an ammonium salt c) the pressing forming a material of wood chips. Process according to claim 1, characterized in that during the hydrothermal and / or mechanical decomposition, at least one acid is released from the second lignocellulose-containing material. 3. Method according to claim 2, characterized in that the acid contributes to the hardening of the aminoplast resin. Process according to claims 2 or 3, characterized in that the acid has a molecular weight of 40 g / mol to 500 g / mol, especially from 40 g / mol to 250 g / mol. Method according to one of claims 2 to 4, characterized in that the acid is a Bronsted acid with a pKa of 2 to 8, especially 3 to 6. Method according to one of claims 2 to 5, characterized in that the acid is a carboxylic acid, being selected especially from the group consisting of formic acid, acetic acid, propanoic acid, butyric acid, pentanoic acid and derivatives thereof. Method according to one of the preceding claims, characterized in that the hydrothermal and / or mechanical decomposition of the second lignocellulose-containing material is carried out at a temperature of 120 to 180 ° C, especially of 140 to 160 ° C. Method according to one of the preceding claims, characterized in that the hydrothermal and / or mechanical decomposition of the second lignocellulose-containing material is carried out at a pressure of 3 to 10 bar, especially at between 4 and 8 bar. Method according to one of the preceding claims, characterized in that the duration of hydrothermal and / or mechanical decomposition is from 2 seconds to 40 minutes, especially from 5 seconds to 30 minutes. Method according to one of the preceding claims, characterized in that the hydrothermal and / or mechanical decomposition is carried out in a preheater tank, a boiler and / or a refiner. Method according to one of the preceding claims, characterized in that the composition contains 0.1 to 15% by weight of the first hardener, especially 0.5 to 10% by weight, in each case with respect to the resin part. solid of the aminoplast resin. Process for manufacturing a wood chip material according to one of the preceding claims, the hydrothermal and / or mechanical decomposition described in step b) comprising the following steps: (i) the hydrothermal decomposition of the second material containing lignocellulose in a boiler and / or a pressure reactor, (ii) mechanical decomposition by grinding the second lignocellulose-containing material from step (i) in a refiner. Method according to one of the preceding claims, characterized in that the wood particles in step a) are selected from the group consisting of wood material of fine particles, wood flakes, thin slices of wood, wood strands, shavings of wood. wood and crushed cuttings. Method according to one of the preceding claims, characterized in that the second material containing lignocellulose is selected from the group consisting of annual plants, useful plants, herbs, leaves, cereals, their components, waste and mixtures thereof. Method according to claim 14, characterized in that the useful plant is selected from the group consisting of straw, wheat, rye, barley, oats, millet, corn, miscanthus, rice, its components, waste and mixtures thereof. Method according to one of the preceding claims, characterized in that the aminoplast resin is a melanin or urea resin. Method according to one of the preceding claims, characterized in that the ammonium salt is selected from the group consisting of ammonium nitrate, ammonium chloride and ammonium sulfate. Method according to one of the preceding claims, characterized in that the composition contains 0.1 to 4% by weight of the second hardener, especially 0.5 to 3.0% by weight, based on the solid resin part. of the aminoplast resin. Method according to one of the preceding claims, characterized in that the wood chip material is a chip plate or an OSB plate. 20. Use of a material containing lignocellulose, hydrothermally and mechanically decomposed, as hardener for an aminoplast resin in a process for the manufacture of a wood chip material according to one of claims 1 to 19.