EP1858677A1

EP1858677A1 - Production of moulded bodies from lignocellulose-based fine particle materials

Info

Publication number: EP1858677A1
Application number: EP06707409A
Authority: EP
Inventors: Ulf Baus; Günter Scherr; Holger Militz; Andreas Krause; Falko Wepner
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2005-03-04
Filing date: 2006-03-03
Publication date: 2007-11-28
Also published as: BRPI0608757A2; NO20074256L; WO2006092330A1; JP2008531800A; KR20080002805A; US20080246177A1; RU2007136554A; AU2006219948A1; CA2599431A1; MX2007010009A; AR054007A1; ZA200708405B; CN101132892A

Abstract

The invention relates to a method for producing moulded bodies from lignocellulose-based fine particle materials and to thus obtainable moulded bodies. The use of aqueous compositions containing at least one type of cross-linkable urea compound for producing lignocellulose-based fine particle materials treated by said composition for producing moulded bodies is also disclosed.

Description

Production of moldings from finely divided materials based on lignocellulose

description

The present invention relates to a process for the production of moldings from finely divided materials based on lignocellulose and the moldings obtainable thereby. The invention also relates to the use of aqueous compositions containing at least one crosslinkable urea compound for the preparation of finely divided materials based on lignocellulose and treated with this composition for the production of moldings.

Moldings based on finely divided materials based on lignocellulose (hereinafter also shaped bodies based on lignocellulose particles), for example based on wood particles, are widely used as construction materials in the construction and furniture sector. Their preparation is generally carried out by gluing the lignocellulose particles with a liquid, usually aqueous composition of binder polymers, shaping the materials so glued and curing. When curing takes place, optionally with crosslinking of the binder, a bonding of the finely divided materials instead, whereby the molding obtains its stability. In the case of wood-plastic composites (WPC), the finely divided materials are embedded in a plastic matrix. An overview of the common types of shaped articles based on lignocellulose particles and the methods for their production H.H. Nimz et al, "Wood - Wood-based Materials," in Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed. on CD-ROM, Wiley-VCH, Weinheim 1997. Molded products based on finely divided lignocellulose particles are mass-marketed and subject to immense cost pressure.

A major problem with moldings based on lignocellulosic particles is their often only moderate to poor resistance to water. This results from the property of the lignocellulosic particles to store water on contact with water or in a humid atmosphere, e.g. in the cell walls. As a result, the shaped bodies swell and their mechanical strength is reduced. In addition, moldings based on lignocellulosic particles, in particular in the moist state, fall from wood-degrading or wood-discoloring organisms, in particular microorganisms, which makes it necessary to equip the shaped bodies with corresponding fungicides and biocides. This in turn represents a not inconsiderable cost factor and is also environmentally disadvantageous.

To improve durability, wood and comparable lignocellulose-based materials are often rendered hydrophobic, e.g. B. by treatment with waxy Impregnating agents. This makes penetration of water into the pores of the material more difficult.

It has been proposed to improve the dimensional stability of wood-based materials such as particleboard and fiberboard and their resistance to wood-destroying organisms by the acetylation of the wood particles by means of anhydrides such as acetic anhydride (see EP-A 213252 and literature cited therein as well as Rowell et al. , Wood and Fiber Science, 21 (1), pp. 67-79). A disadvantage is the high cost of treatment and the unpleasant odor of the material thus treated, so that these measures have not prevailed in the market.

Other chemicals, such as isocyanates, siloxanes and acrylamide, have also been proposed for the modification of lignocellulosic fibers (J. Appl. Polym ScL, 73 (1999) 2493-2505). Overall, however, these measures are not satisfactory.

WO 2004/033170 and WO 2004/033171 describe the use of impregnating agents based on hydroxymethyl- or alkoxymethyl-modified urea derivatives, such as 1,3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one, alkanol-modified bis (hydroxymethyl ) 4,5-dihydroxyimidazolidinone, 1, 3-bis (hydroxymethyl) -urea, 1, 3-bis (methoxymethyl) urea, 1-hydroxymethyl-3-methylurea,

1, 3-bis (hydroxymethyl) imidazolidin-2-one, 1, 3-dimethyl-4,5-dihydroxyimidazolidin-2-one or tetra (hydroxymethyl) acetylenediurea for improving the durability, dimensional stability and surface hardness of wood bodies made of solid wood. The problem of the dimensional stability of molded articles based on finely divided lignocellulosic materials is not addressed.

Accordingly, it is the object of the present invention to provide a finely divided material based on lignocellulose, from which moldings having improved dimensional stability on exposure to moisture can be produced. The finely divided material should also be inexpensive to produce in view of the use in the production of mass products such as fiber and chipboard.

It has surprisingly been found that these and other objects can be achieved by lignocellulose-based finely divided materials treated with an aqueous composition comprising at least one crosslinkable urea compound, wherein the crosslinkable urea compound is selected from urea compounds H which contain at least one N -bonded group of the formula CH ₂ OR, in which R is hydrogen or C 1 -C ₄ -alkyl, and / or a 1, 2-bishydroxyethane-1, 2-diyl group bridging the two nitrogen atoms of the urea, precondensates of the urea compound H, and reaction products or mixtures of the urea compound H with at least one alcohol selected from C _r C ₆ -alkanols, C ₂ -C ₆ -polyols and oligoethylene glycols.

In the following, finely divided materials based on lignocellulose are also referred to as finely divided lignocellulose materials or lignocellulose particles for short. Accordingly, treated according to the invention, finely divided materials based on lignocellulose as treated or inventive finely divided lignocellulosic materials or as treated or inventive lignocellulose particles and untreated finely divided materials based on lignocellulose as untreated finely divided lignocellulosic materials or untreated lignocellulosic particles.

Treatment is understood to mean impregnation or impregnation of the untreated finely divided lignocellulose materials with the aqueous composition and, if appropriate, drying and / or curing of the impregnated material or of the curable constituents absorbed by the impregnated material.

Finely divided lignocellulosic materials which have been impregnated with the aqueous composition of the crosslinkable urea compounds and which have been treated in such a way that the crosslinking of the urea compounds (curing) has occurred, give moldings in conventional further processing, which are distinguished by superior mechanical properties, in particular improved properties Dimensional stability, d. H. less swelling on contact with moisture and higher surface hardness. In addition, the moldings are less prone to attack with wood-destroying microorganisms, such as wood-destroying harmful fungi and wood-destroying bacteria, whereby the cost of corresponding fungicides and biocides can be reduced and frequently even avoided. The crosslinking of the crosslinkable urea compounds of the aqueous composition takes place following the impregnation, optionally in a separate drying / curing step at elevated temperature and / or during the subsequent shaping process after the gluing with a customary for the molding of the binder, optionally by adding a the curing of the urea compounds promoting catalyst.

Accordingly, a first subject of the present invention is the use of an aqueous composition containing at least one crosslinkable urea compound from the group of the urea compounds H, which is at least one N-linked group of the formula CH ₂ OR, where R is hydrogen or C ₁ -C ₄ - Alkyl, and / or a two nitrogen atoms of the urea bridging 1, 2-bishydroxyethane-1, 2-diyl group have, precondensates of the urea compound H, and reaction products or mixtures of the urea compound H with at least one alcohol selected from C _r C ₆ -alkanols, C ₂ -C ₆ -polyols and oligoethy- lenglykolen, for the preparation of treated with this composition finely divided materials based on lignocellulose for the production of moldings.

The invention further relates to the treated lignocellulose materials obtainable in this way and their use for the production of moldings. The invention also relates to the molded articles produced using such impregnated lignocellulosic materials.

Aqueous compositions of crosslinkable urea compounds of the type in question are described, for example, in WO 2004/033170 and WO 2004/033171 cited above and in K. Fisher et al. "Textile Auxiliaries - Finishing Agents" Chap. 7.2.2 in Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed. on CD-ROM, Wiley-VCH, Weinheim 1997 and literature cited there, eg. B. US 2,731,364

US 2,930,715 known and are commonly used as crosslinkers for textile finishing. Reaction products of urea compounds with alcohols, eg. B. modified 1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidinon-2 (mDMDHEU) are known for example from US 4,396,391 and WO 98/29393. Incidentally, urea compounds H and their reaction products and precondensates are commercially available, for example under the trade names Fixapret® CP and Fixapret® ECO from BASF Aktiengesellschaft.

The urea compounds contained in the aqueous compositions are low molecular weight compounds or oligomers of low molecular weight, which are usually completely dissolved in water. The molecular weight of the urea compounds is usually below 400 daltons. These compounds are thought to allow the compounds to penetrate into the cell walls of the lignocellulosic particle and, upon curing, improve the mechanical stability of the cell walls and reduce their swelling caused by water.

Examples of crosslinkable urea compound of the curable, aqueous composition include, but are not limited to:

1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one (DMDHEU),

1,3-Bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one which is modified with a C ₁ -C ₆ -alkanol, a C ₂ -C ₆ -polyIl, an oligoethylene glycol (modified DMDHEU or mDMDHEU) , 1, 3-bis (hydroxymethyl) urea, - 1, 3-bis (methoxymethyl) urea;

1-hydroxymethyl-3-methylurea, 1, 3-bis (hydroxymethyl) imidazolidin-2-one (dimethylolethyleneurea), 1,3-bis (hydroxymethyl) -1,3-hexahydropyrimidin-2-one (dimethylolpropyleneurea),

1, 3-bis (methoxymethyl) -4,5-dihydroxyimidazolidin-2-one (DMeDHEU) and - tetra (hydroxymethyl) acetylene diurea.

In a preferred embodiment of the invention, the crosslinkable urea compound is 1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one and one having a C _r C ₆ alkanol, a C ₂ -C ₆ polyoxy, a Oligoethylenglykol modified 1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one selected.

MDMDHEU reaction products of 1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2 with a -C ₆ alkanol, a C ₂ -C ₆ -polyol, an oligoethylene glycol or mixtures of these alcohols. Suitable C _1-6 -alkanols are, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol and n-pentanol, preference is given to methanol. Suitable polyols are ethylene glycol, diethylene glycol, 1, 2 and 1, 3-propylene glycol, 1, 2, 1, 3, and 1, 4-butylene glycol, glycerol. Suitable oligoethylene glycols are, in particular, those of the formula HO (CH ₂ CH ₂ O) _n H where n is from 2 to 20, of which diethylene glycol and triethylene glycol are preferred. To produce mDMDHEU, DMDHEU are mixed with the alkanol, the polyol or the polyethylene glycol. Here, the monohydric alcohol, the polyol, or the oligo- or polyethylene glycol are usually used in a ratio of 0.1 to 2.0, in particular 0.2 to 2 molar equivalents, based on DMDHEU. The mixture of DMDHEU, the polyol or the polyethylene glycol is usually reacted in water at temperatures of preferably 20 to 70 ⁰ C and a pH of preferably 1 to 2.5, wherein the pH after the reaction usually to a Range is set from 4 to 8.

The curable aqueous compositions may in addition to the urea compounds H or their reaction products or precondensates (component A) and one or more of the aforementioned alcohols, C _r C ₆ alkanols, C ₂ -C ₆ polyols, ethylene glycols oligomers or mixtures of these alcohols contained (component C). Suitable Ci _-6 alkanols are for example methanol, is ethanol, n-propanol, iso-propanol, n-butanol and n-pentanol, preferably methanol. Suitable polyols are ethylene glycol, diethylene glycol, 1, 2 and 1, 3-propylene glycol, 1, 2, 1, 3, and 1, 4-butylene glycol, glycerol. Suitable oligoethylene glycols are, in particular, those of the formula HO (CH ₂ CH ₂ O) _n H where n is from 2 to 20, of which diethylene glycol and triethylene glycol are preferred.

The concentration of urea compound H or its reaction product or precondensate in the aqueous composition is usually in the range of 1 up to 60% by weight, often in the range of 10 to 60% by weight and in particular in the range of 15 to 50% by weight, based on the total weight of the composition. If the curable, aqueous composition comprises one of the abovementioned alcohols, its concentration is preferably in the range from 1 to 50% by weight, in particular in the range from 5 to 40% by weight. The total amount of component A) and component C) usually constitutes from 10 to 60% by weight and in particular from 20 to 50% by weight of the total weight of the aqueous composition.

In addition to the components A) and, if appropriate, C), the aqueous composition may also contain a catalyst K which brings about the crosslinking of the urea compound H or of its reaction product or precondensate. In general, as catalysts K metal salts from the group of metal halides, metal sulfates, metal nitrates, metal phosphates, Metalltetrafluoroborate; boron trifluoride; Ammonium salts from the group of ammonium halides, ammonium sulfate, ammonium oxalate and diammonium phosphate; and organic carboxylic acids, organic sulfonic acids, boric acid, sulfuric acid and hydrochloric acid.

Examples of metal salts suitable as catalysts K are in particular magnesium chloride, magnesium sulfate, zinc chloride, lithium chloride, lithium bromide, aluminum chloride, aluminum sulfate, zinc nitrate and sodium tetrafluoroborate.

Examples of suitable as catalysts K ammonium salts are in particular ammonium chloride, ammonium sulfate, ammonium oxalate and diammonium phosphate.

Particularly suitable catalysts K are water-soluble organic carboxylic acids such as maleic acid, formic acid, citric acid, tartaric acid and oxalic acid, furthermore benzenesulfonic acid, p-toluenesulfonic acid but also inorganic acids such as hydrochloric acid, sulfuric acid, boric acid or mixtures thereof.

Preferably, the catalyst K is selected from magnesium chloride, zinc chloride, magnesium sulfate, aluminum sulfate or mixtures thereof, magnesium chloride being particularly preferred.

The catalyst K is usually added to the aqueous composition only shortly before the impregnation of the lignocellulosic material. It is usually used in an amount of 1 to 20 wt .-%, in particular 2 to 10 wt .-%, based on the total weight of the components contained in the curable, aqueous composition A) and optionally C). The concentration of the catalyst, based on the total weight of the curable, aqueous composition, is usually in the range of 0.1 to 10 wt .-% and in particular in the range of 0.5 to 5 wt .-%. Furthermore, the aqueous composition used for impregnation may contain a part or the total amount of the binders required for the production of the moldings, which are explained in more detail below. If desired, the concentration of binder in the aqueous composition is usually in the range of 0.5 to 25% by weight, often in the range of 1 to 20% by weight and in particular in the range of 5 to 15% by weight. based on the total weight of the aqueous composition and calculated as dry glue components (ie, without any solvent or Verdünnungsmittelbestanteile of the binder).

It is assumed that the binder components of the sizing composition, unlike crosslinkable urea compounds, the catalyst K and the optionally present alcohols of component C) are not or only to a small extent absorbed by the cell walls of the lignocellulose particles but remain largely on the surface of the particles and therefore in the subsequent shaping process of the production of the shaped bodies as binders are available.

The preparation of the finely divided materials based on lignocellulose impregnated with the aqueous composition can basically be carried out in two different ways.

Thus, according to a first embodiment of the invention, a coarse, untreated material based on lignocellulose, z. B. wood blocks with the aqueous compositions containing a catalyst K, in the manner described in WO 2004/033170 and WO 2004/033171 described manner and then comminute, z. As by machining, defibering or grinding, or the obtained during processing or recycling of the resulting materials obtained treated wood chips or fibers.

Preferably, however, an untreated, finely divided lignocellulose-based material will be impregnated with the curable aqueous composition and the catalyst K and subsequently exposed to conditions which cause crosslinking of the urea compounds contained in the composition and thus curing of the composition. The aqueous composition and the catalyst K can be applied together in one composition or in two separate compositions to the untreated, lignocellulose-based, finely divided material. Usually, however, the catalyst K will be incorporated into the aqueous composition before application. However, it is also conceivable to use the finely divided material based on lignocellulose with a first aqueous preparation which contains the catalyst K in dissolved form and a second aqueous composition. Composition, which contains the crosslinkable urea compound and optionally the alcohol component C), simultaneously or successively to impregnate.

The type of untreated finely divided lignocellulose material depends in a known manner on the shaped article to be produced. Examples of suitable finely divided lignocellulosic materials include, but are not limited to, finely divided wood materials such as wood chips, e.g. For example, from machined round and billet wood, chipped industrial wood and industrial waste wood, sawmill and veneer waste, shavings from thermomechanically digested wood, planing and peeling chips, wood chips and wood chips, furthermore lignocellulose-containing raw materials other than wood, such as bamboo, bagasse, cotton stalks , Jute, sisal, straw, flax, coconut fibers, banana fibers, reeds, eg Miscanthus, ramie, hemp, manila hemp, esparot (alfagras), rice husks and cork.

The untreated finely divided lignocellulosic materials may be present in the form of granules, flour, or preferably shavings, including sawdust and shavings, fibers and / or shavings. These include materials of wood and bamboo, such as wood fibers, wood chips, wood chips and wood chips or bamboo fibers, bamboo chips and bamboo chips and their mixtures, particularly preferred. In particular, these are finely divided materials made of wood. The types of wood that make up the finely divided materials include, for example, softwoods such as Douglas fir, spruce, pine, larch, pine, fir, cedar, stone pine and deciduous trees such as horn, acacia, birch, beech, oak, alder, ash, aspen , Hazel, hornbeam, cherry, linden, poplar, robinia, elm, walnut, willow, Turkey oak and the like.

The dimension, d. H. The dimensions (length, thickness) comprising at least 90% of the finely divided lignocellulosic materials are usually in the range of 0.1 to 20 mm, in particular 0.5 to 10 mm and especially 1 to 5 mm, in the case of elongated formed finely divided materials with a length / width ratio> 5 the length, which comprise at least 90% of the particles, may also exceed 10 mm and may be up to 200 mm. The average width or thickness of elongated particles is typically in the range of 0.1 to 10, in particular in the range of 0.2 to 5 mm and especially in the range of 0.3 to 3 mm.

The impregnation or impregnation of the untreated finely divided materials based on lignocellulose can, for. B. by dipping the fibers in the aqueous composition, by applying vacuum, optionally in combination with pressure, or by spraying. The conditions will usually be chosen so that the amount of curable constituents of the aqueous composition taken up is at least 1% by weight, based on the dry mass of the untreated material. The absorbed amount of curable Ingredients may be up to 100 wt .-%, based on the dry weight of the untreated lignocellulosic materials and is often in the range of 1 to 60 wt .-%, preferably in the range of 5 to 50 wt .-%, and in particular in the range of 10 to 30 wt .-%, based on the dry matter of the untreated material used. Usually, the impregnation is carried out at ambient temperature, typically in the range of 15 to 40 ^° C.

The moisture content of the impregnated, untreated lignocellulosic materials is not critical and can be, for example, up to 100%. Here and below, the term "moisture" is synonymous with the term residual moisture content according to DIN 52183. It is often in the range of 1 to 80% and in particular 5 to 50%.

During dipping, the untreated finely divided lignocellulosic materials, which advantageously have a moisture in the range of 1% to 100%, are immersed in the aqueous composition in a container over a period of a few seconds to 12 hours, in particular 1 minute to 60 minutes or suspended in this. Hereby, the finely divided lignocellulosic material absorbs the aqueous impregnating composition, the amount of curable material absorbed by the fine lignocellulosic material being determined by the concentration of hardenable components (ie component A) and C)) in the aqueous composition, temperature and duration of treatment Components can be controlled. The amount of curable components actually absorbed can be determined by the person skilled in the art in a simple manner via the weight increase of the finely divided lignocellulose material and the concentration of the aqueous composition.

The impregnation can also be achieved by the use of reduced pressure, which may optionally be followed by an elevated pressure phase. For this purpose, the finely divided lignocellulose material under reduced pressure, which is often in the range of 10 to 500 mbar and in particular in the range of 50 to 100 mbar, brought into contact with the aqueous composition, for. By dipping or suspending in the curable aqueous composition. The time period is usually in the range of 1 minute to 1 hour. Optionally, a phase at elevated pressure, z. B. in the range of 1 bar to 20 bar, to. The duration of this phase is usually in the range of 1 min to 6 h, in particular 5 min to 1 h. Hereby, the finely divided lignocellulosic material absorbs the aqueous impregnating composition, whereby the concentration of curable constituents in the aqueous composition, the applied pressure, the temperature and the duration of treatment can control the amount of hardenable constituents taken up by the finely divided lignocellulosic material. The amount actually absorbed can also be calculated here by the weight increase of the finely divided lignocellulosic material. In a further embodiment of the invention, the impregnation is carried out by spraying the untreated lignocellulose particles with the aqueous composition. The lignocellulose particles advantageously have a moisture content of not more than 50%, for example in the range of 1% to 30%. The spraying is usually carried out at temperatures in the range of 15 to 50 ^° C. The concentration of curable constituents in the aqueous composition, the amount applied, the temperature and the duration of the spraying allow the amount of lignocellulosic material to be absorbed be controlled on curable ingredients. The actually absorbed amount of curable components results directly from the sprayed amount of aqueous composition. The spraying may be carried out in a conventional manner in all devices suitable for spraying solids, e.g. As in spray towers, fluidized bed devices and the like.

The impregnation can also be done by means of ultrasound.

The impregnated, finely divided lignocellulose particles thus obtained are, if appropriate after a drying step and / or a curing step, further processed into shaped bodies.

In many cases, the further processing comprises gluing the treated finely divided material with a liquid or powdered preparation of a binder and shaping and hardening the glued material to form a shaped body. In other cases, eg. In the production of WPCs, the further processing comprises mixing the material obtained in step i) with a thermoplastic polymer and molding the mixture. In this case, the preparation in step i) usually comprises an impregnation and a drying or curing step.

The invention therefore also relates to a process for the production of moldings from finely divided materials based on lignocellulose, comprising

i) providing a lignocellulose-based finely divided material impregnated with the curable, aqueous composition described herein and optionally cured,

ii) gluing the lignocellulose-based finely divided material obtained in step i) or a mixture thereof with other finely divided materials with a liquid or pulverulent preparation of a binder; and iii) shaping and hardening the glued finely divided material into a shaped body,

or

ii ') mixing the treated, preferably dried and / or cured finely divided material based on lignocellulose obtained in step i) with a thermoplastic polymer and

iii ') molding the mixture into a shaped article.

The invention also relates to the moldings obtainable by the process.

If the provision of the treated finely divided lignocellulosic materials comprises the impregnation of untreated lignocellulosic materials, it is possible to carry out a drying step, in the following also a predrying step, following the impregnation in step i) and before the gluing in step ii). In this case, the volatile constituents of the aqueous composition, in particular the water and excess organic solvents, which do not react in the curing / crosslinking of the urea compounds, partially or completely removed. In addition, depending on the selected drying temperature, partial or complete curing / crosslinking of the curable constituents contained in the composition can take place. The predrying / curing of the impregnated materials is usually carried out at temperatures of 50 ° C to 220 ⁰ C, in particular in the range of 80 to 200 ⁰ C. If curing is desired, the drying is preferably carried out above 100 ⁰ C. The curing / drying can in a conventional fresh air exhaust system, z. B. a drum dryer, performed. Pre-drying preferably takes place in such a way that the moisture content of the finely divided lignocellulosic materials after predrying is not more than 30%, in particular not more than 20%, based on the dry mass. It may be advantageous to carry out the drying / curing up to a moisture content <10% and in particular <5%, based on the dry mass. The moisture content can be easily controlled by the temperature, the duration and the pressure selected during pre-drying.

However, a predrying step is generally not required, and devolatilization and crosslinking of the curable constituents of the aqueous composition can also be carried out following the gluing in step ii) or in the shaping and curing step iii). Such a procedure not only has the advantage of simplifying the procedure, but also allows shorter gluing and shaping times. Therefore, in a preferred Embodiment preferably no separate drying step is performed and the gluing is carried out immediately after impregnation or simultaneously therewith.

If the aqueous composition already contains an amount of binder sufficient for the production of the shaped article, the treatment step i) and the gluing ii) coincide in time and the removal of the volatile constituents and the crosslinking of the curable constituents of the aqueous composition take place in the shaping and curing step iii).

If the aqueous composition used for impregnation in step i) contains no amount of binder sufficient for the production of the shaped bodies, then the impregnated and optionally predried and cured lignocellulose particles are glued in the usual manner with the binder required for the production of the shaped bodies.

Gluing can be done in the usual way. Optionally, further fine-particle materials, additives, catalysts or auxiliaries forming the shaped body are added at this stage.

The type of binder depends in a conventional manner on the nature of the molded article to be produced. Suitable binders are described, for example, in A. Pizzi (ed.): Wood Adhesives, Marcel Dekker, New York 1983. Examples of binders are:

i) thermally curable binders (reactive binders) such as aminoplast resins, phenolic resins, isocyanate resins, epoxy resins and polycarboxylic acid resins;

ii) thermoplastic materials such as polyethylene, polypropylene, polystyrene resins, polysulfones, polyester resins; and

iii) film-forming polymers, e.g. For example, aqueous polymer dispersions based on styrene acrylates, polyacrylates (acrylic acid ester / methacrylic acid ester copolymers), vinyl acetate polymers (polyvinyl acetate), styrene-butadiene copolymers and the like.

Preferred binders are the thermally curable binders mentioned in group i) and mixtures thereof with film-forming polymers of group iii), the thermally curable binders preferably being used in the form of aqueous preparations. Preferred binders are aminoplast resins, phenolic resins, isocyanate resins, polyvinyl acetate and polycarboxylic acid resins.

Particularly suitable aminoplast resins are formaldehyde condensates of urea (urea-formaldehyde condensates) and of melamine (melamine-formaldehyde condensates). They are available as aqueous solutions or powders under the names Kaurit ^® and Kauramin ^® (Prod. BASF) and contain urea and / or melamine-formaldehyde precondensates. Typical phenolic resins are phenol-formaldehyde condensates, phenol-resorcinol-formaldehyde condensates and the like. Also suitable are mixed condensates of aminoplast resins and phenolic resins. Examples of mixed condensates of aminoplast resins and phenolic resins are urea-melamine-formaldehyde condensates, melamine-urea-formaldehyde-phenol condensates, and mixtures thereof. Their preparation and use for the production of moldings from finely divided lignocellulosic materials is well known. Preference is given to urea-formaldehyde resins and of these in particular those having a molar ratio of 1 mol of urea to 1.1 to 1.4 moles of formaldehyde.

In the processing of aminoplast resins and phenolic resins, a transition of the soluble and meltable precondensates into infusible and insoluble products takes place. In this process, known as curing, it is known that continuous cross-linking of the precondensates occurs, which is generally accelerated by hardeners. As curing agents, the hardener known to those skilled in the art for urea, phenol and / or melamine-formaldehyde resins can be used, such as acid-reacting and / or acid-releasing compounds, for. For example, ammonium or amine salts. In general, the proportion of hardener in a glue resin liquor is from 1 to 5% by weight, based on the liquid resin content.

As Isocyanatharze all common resins based on Methylendiphenylenisocyanaten (MDI) resins are suitable. They usually consist of a mixture of monomers and oligomeric di- or polyisocyanates, the so-called precondensates, which are capable of reacting with the cellulose, lignin and the moisture of the lignocellulose particles. Suitable isocyanate resins are for example as Lupranat® ^® grades (from Elastogran) are commercially available.

Examples of reactive polycarboxylic acid resins are compositions comprising:

i) a polymer P of ethylenically unsaturated monomers which is from 5 to 100, preferably from 5 to 50,% by weight of an ethylenically unsaturated acid anhydride or an ethylenically unsaturated dicarboxylic acid whose carboxylic acid groups can form an anhydride group, or their reaction products with alkanolamines (Monomers a)), and 0 to 95 wt .-%, preferably 50 to 95 % By weight of monomers b) other than the monomers a); and

ii) at least one alkanolamine A- (OH) ₂ having at least two hydroxyl groups and / or an alkoxylated polyamine and

iii) optionally a water-insoluble, water-dispersible film-forming polymer P '.

Reactive polycarboxylic acid resins are known in the art and are used in z. For example, EP-A-882 093, WO 97/45461, WO 99/09100, WO 99/02591, WO 01/27163 and WO 01/27198.

Particular preference is given to polymers P which contain maleic acid and / or maleic anhydride as monomers a).

Preferred monomers b) are ethylenically unsaturated C ₃ -C ₆ -monocarboxylic acids such as acrylic acid, methacrylic acid, olefins such as ethene, propene, butene, isobutene, cyclopentene, diisobutene, vinylaromatics such as styrene, alkyl vinyl ethers, eg. Methyl vinyl ether, ethyl vinyl ether, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, vinyl acetate, butadiene,

Acrylonitrile or mixtures thereof. Particularly preferred monomers b) are acrylic acid, methacrylic acid, ethene, acrylamide, styrene and acrylonitrile or mixtures thereof.

In particular, polymers P are preferred in which the monomer b) comprises at least one C ₃ -C ₆ -monocarboxylic acid, preferably acrylic acid as comonomer b).

As component A- (OH) ₂ , alkanolamines having at least two OH groups are used, such as diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, methyldiethanolamine, butyldiethanolamine and methyldiisopropanolamine. Preferred is triethanolamine. The component A- (OH) _{2 also} includes alkoxylated, in particular ethoxylated polyamines, as described in WO 97/45461, z. B. Compounds of the formulas I ₁ described therein and in particular Ia, Ie and If.

Suitable components P 'and also binders of group iii) are in principle all water-insoluble polymers which are film-forming and dispersible in water. These include, in particular, emulsion polymers and the powders produced therefrom, as described, for. B. in WO 01/27198 be referred to as polymers A1. The polymers P 'often have a glass transition temperature in the range of -10 to +150 ⁰ C and in particular in the range of +20 to +120 ⁰ C. In particular, these are copolymers based on styrene / butadiene, based on Styrene / acrylic acid alkyl esters and those based on alkyl methacrylate / alkyl acrylate.

For the preparation of the polycarboxylic resins, the polymer P and the alkanolamine A- (OH) _{2 are} preferably used in such a ratio to one another that the molar ratio of carboxyl groups of the component P and the hydroxyl groups of the component A- (OH) ₂ 20: 1 to 1: 1, preferably 8: 1 to 5: 1 and more preferably 5: 1 to 1, 7: 1 (the anhydride groups are calculated here as 2 carboxyl groups).

The binder is usually used in amounts of 0.5 to 30 wt .-%, often from 1 to 20 wt .-%, in particular in amounts of 5 to 15 wt .-%, based on the treated lignocellulosic materials.

The preferred binders of group i) can of course also be used in mixtures with one another or in mixtures with binders of groups ii) and in particular iii).

In addition, for the production of the moldings customary auxiliaries and additives can be used as the above-mentioned hardener, d. H. Catalysts that cause a faster crosslinking of the binder.

The excipients include z. As bactericides or fungicides and water repellents to increase the water resistance of the moldings. Suitable hydrophobizing agents are customary aqueous paraffin dispersions or silicones. In addition, wetting agents, thickeners, plasticizers, retention aids can be used in the preparation. These are often added to the binder composition. Frequently, the binder compositions also contain coupling reagents, such as alkoxysilanes, for example 3-aminopropyltriethoxysilane, soluble or emulsifiable oils as lubricants and dust binders, and wetting assistants.

Common additives include inert fillers such as aluminum silicates, quartz, precipitated or fumed silica, light and heavy spar, talc, dolomite or calcium carbonate; coloring pigments, such as titanium white, zinc white, iron oxide black, etc.

Finally, in the production of the moldings conventional fire retardants, such as. As aluminum silicates, aluminum hydroxides, borates and / or phosphates are used.

The gluing is carried out according to the usual procedure, for. B. by mixing the finely divided, impregnated lignocellulosic materials with the binder in the usual Mixing apparatus for mixing liquid with solid materials, by vortexing the lignocellulosic materials in the air stream and injecting the binder, preferably in the form of a liquid binder composition, in the so-called blow-line process.

The glue-coated mixture of lignocellulose-containing materials and the binder composition can be pre-dried to 200 ⁰ C prior to molding to remove volatiles at elevated temperature, for example at temperatures of 10 to. Depending on the type of binder composition, however, the removal of volatile constituents may also be omitted or carried out during the shaping step.

Following the gluing and optionally predrying takes place a shaping step, in a conventional manner usually at elevated temperature, for. Example, at temperatures of 50 to 300 ⁰ C, preferably 100 to 250 ⁰ C and particularly preferably 140 to 225 ⁰ C and usually at elevated pressures of generally 2 to 200 bar, preferably 5 to 100 bar, particularly preferably 20 to 50 bar , he follows.

Suitable methods of shaping are familiar to the expert and include, for. B. extrusion process, deep drawing and in particular the hot pressing, these processes discontinuously or continuously, for. B. as rolling presses, sliding presses, calendering presses, extrusion presses, steam injection presses, can be configured. An overview of common methods can be found z. In Ullmann's Encyclopedia of Industrial Chemistry, "Wood - Wood Based Materials", Chapters 2.3.1, 2.3.2 and 2.3.3, 5th edition on CD-ROM, Wiley-Verlag-Chemie, Weinheim 1997.

In the temperatures and pressure prevailing during shaping, the lignocellulose particles stick together and, depending on the type of binder, melting and / or crosslinking of the binder constituents takes place, so that a stable shaped body is formed on cooling and removal of the mold.

The shaped bodies can be of any shape and comprise flat shaped bodies such as plates or mats, or have a 3-dimensional configuration, for example specially shaped molded parts. Examples of sheet-like molded articles include oriented structural board (OSB), chipboard, wafer boards, insulating boards, medium density (MDF) and high density (HDF) fiberboard. The molded articles according to the invention also include OSL boards and OSL molded parts (Oriented Strand Lumber), as well as PSL boards and PSL molded parts (parallel beach lumber). The molded articles also include molded parts made of WPC (wood-plastic composites). The inventive method is particularly suitable for the production of moldings, wherein the lignocellulosic material is wood. Depending on the size of the lignocellulose-containing particles used, a distinction is made between OSB (oriented structural board) boards, chipboard, wafer boards, OSL boards and OSL molded parts (Oriented Strand Lumber), PSL boards and PSL moldings (parallel beach lumber). Insulation boards and medium density (MDF) and high density (HDF) fiberboard and the like.

The inventive method is particularly suitable for the production of so-called WPC (wood-plastic composites), as z. In WO 96/34045, the literature cited therein, and in general in Austria. Kunststoffzeitschrift 35, 2004, 10-13 and in Klauditzforum 5th ed. 6/2004. The processes known for the production of WPC can be carried out in an analogous manner with the lignocellulose materials treated according to the invention.

For the preparation of the WPCs, the finely divided lignocellulosic material treated according to the invention, after having previously carried out a drying / curing step, with at least one thermoplastic plastic material, for. B. thermoplastic polymers based on poly-C ₂ -C ₆ -olefinen such as polyethylene, polypropylene and the like, or based on poly-C ₂ -C ₄ halo-olefins such as polyvinyl chloride, polyvinylidene chloride or copolymers of vinyl chloride with vinylidene chloride, vinyl acetate and / or C ₂ -C ₆ olefins and then subjected to a shaping process, usually an injection molding or extrusion process. The amount of thermoplastic polymer is usually from 20 to 90 wt .-% and in particular 30 to 80 wt .-%, based on the total mass of. Accordingly, the fraction of finely divided lignocellulosic material treated according to the invention is in the range from 10 to 80% by weight and in particular from 20 to 70% by weight, based on the total weight of the WPC. In addition, the WPCs customary additives such as adhesion promoters (eg organosilanes, maleic anhydride, isocyanates), pigments, light stabilizers, lubricants or fire retardant components can be added. The addition of biocides, however, is not required.

The finely divided lignocellulosic materials treated according to the invention are particularly suitable for the production of wood-based materials, such as chipboard and wood-fiber boards, including HDF, MDF, OSB, OSL and PSL (see Ullmann's Encyclopedia of Industrial Chemistry, loc. Cit.), Which are obtained by gluing cut parts Wood such. As wood chips, wood chips, wood chips and / or wood fibers are produced.

The production of chipboard is generally known and is described, for example, in HJ Deppe, K. Ernst Taschenbuch der Spanplattentechnik, 2nd edition, publisher Leinfei- 1982, and can be used analogously in the process according to the invention.

In chipboard production, the gluing of the previously dried chips takes place in continuous mixers. Usually, different chip fractions in different mixers are glued differently and then separated (multilayer boards) or poured together. Chips are preferably used whose mean chip thickness is on average 0.1 to 2 mm, in particular 0.2 to 0.5 mm, and which contain less than 6% by weight of water. The binder composition is applied as evenly as possible to the wood chips, for example by spraying the binder composition in finely divided form onto the chips. The glued wood chips are then spread to a layer with a uniform surface as possible, with the thickness of the layer depends on the desired thickness of the finished chipboard. The litter layer is optionally precompressed cold and at a temperature of z. B. 100 to 250 ⁰ C, preferably from 140 to 225 ⁰ C by applying pressures of usually 10 to 750 bar pressed to a dimensionally stable plate. The required pressing times can vary within a wide range and are generally between 15 seconds to 30 minutes.

The necessary to produce medium density fiberboard (MDF) wood fibers suitable quality can potential mill by milling in SPE or so-called refiners are prepared at temperatures of about 180 ⁰ C from bark-free wood chips.

In MDF and HDF board production, the fibers are glued after the refiner in the blow-line. For gluing, the wood fibers are generally fluidized with a stream of air and the binder composition is injected into the fiber stream thus produced ("blow-line" method). The glued fibers then pass through a dryer in which they are dried to humidities of 1 to 20 wt .-%. In some cases, the fibers are first dried and subsequently glued in special continuous mixers. A combination of blow-line and mixer feed is also possible. The ratio of wood fibers to binder composition, based on the dry content or solids content, is usually 40: 1 to 3: 1, preferably 20: 1 to 4: 1. The glued fibers are in the fiber stream at temperatures of z. B. 130 to 180 ⁰ C dried, sprinkled to a nonwoven fabric, optionally cold precompressed and pressed at pressures of 20 to 40 bar to plates or moldings.

In OSB production, the wood chips (strands) are optionally separated after drying in middle and outer layer material and glued separately in continuous mixers. To complete the panels, the glued wood chips are then closed Mats poured, optionally cold precompressed and pressed in heated presses at temperatures of 170 to 240 ⁰ C to plates.

The glued wood fibers can also, such. As described in DE-OS 2 417 243, are processed into a transportable fiber mat. This semi-finished can then in a second, temporally and spatially separate step to plates or moldings, such as. B. interior door panels of motor vehicles, further processed.

Other lignocellulosic materials, eg. As natural fiber materials such as sisal, jute, hemp, ramie, straw, flax, coconut fibers, banana fibers and other natural fibers can be processed using plates known per se into plates and moldings. The natural fiber materials can also be used in mixtures with plastic fibers, eg. As polypropylene, polyethylene, polyester, polyamides or polyacrylonitrile can be used. These synthetic fibers can also act as co-binders in addition to the above-mentioned binder composition. The proportion of plastic fibers is preferably less than 50 wt .-%, in particular less than 30 wt .-% and most preferably less than 10 wt .-%, based on all chips, chips or fibers. The processing of the fibers can be carried out according to the method practiced in fibreboards. However, preformed natural fiber mats can also be impregnated with the binders according to the invention, if appropriate with the addition of a wetting aid. The impregnated mats are then in the wettable or pre-dried state z. B. at temperatures between 100 and 250 ⁰ C and pressures between 10 and 100 bar pressed into plates or moldings.

Due to their high resistance, the moldings according to the invention are suitable for a variety of different applications, in particular for applications in which they are exposed to weathering and moisture, e.g. as a basis for structural components in house building and shipbuilding, e.g. for interior and exterior walls, floor construction, for the manufacture of cladding in the home, ship and automobile industry, e.g. as exterior cladding, interior trim, boot and engine compartment linings, as underlay for decorative panels such as ceiling, wall and prefabricated parquet panels, as components and panels in the furniture industry and for the home improvement sector etc.

The following examples are merely illustrative of the examples of the invention and are not intended to be limiting.

The stated moisture contents were determined according to DIN 52183. Example 1 :

The impregnating agent used was a 50% strength aqueous solution of a diethylene glycol-methanol-modified DMDHEU (mDMDHEU) which had been mixed with 1.5% MgCl ₂ .6H ₂ O.

Thermomechanically digested spruce wood chips with a mean fiber length (90% value) and a moisture content of 11% were introduced by means of a metal basket in an impregnation plant. The impregnation system was exposed for 30 minutes to a vacuum of 100 mbar and then flooded with the impregnating agent. Subsequently, a pressure of 10 bar was applied for one hour. The printing phase was stopped and the residual liquid was removed. The chips obtained in this way were subsequently dried in a dryer at 50 ^° C. for 4 hours.

Example 2:

In an analogous manner to Example 1, wood chip shavings with average dimensions of 0.5 mm × 5 mm × 100 mm were impregnated and then dried.

Example 3:

The pine wood shavings obtained in Example 2, impregnated were heated in a drying oven for 1 hour at 130 ⁰ C to give cured Kiefemholzspäne received.

Example 4: Production of a chipboard

5400 g of dried chips from Example 1 were admixed with 1628 g of the composition given in Table 1 and 3370 g of this were poured into a mold (56.5 cm × 44 cm). The material was pressed in a press at 190 ⁰ C to a thickness of 18 mm in 230 s to a chipboard.

The chipboard contained 14% solid resin / dry chips, 0.5% solid wax / dry chips (atro = wt .-%, based on dry chips).

Table 1

Urea-formaldehyde resin, 68% 100.0 T

Paraffin emulsion, 60% 6.3 T

Ammonium nitrate solution. 52% 4.0 T

T = parts by weight Example 5: Production of an MDF board

1000 g of dry fibers from Example 3 were admixed with the glue formulation given in Table 2 and dried to a moisture content of 8%. Of these, 920 g were poured in a mold (30 cm x 30 cm). The material was pressed in a press at 190 ⁰ C to a thickness of 12 mm in 300 s to an MDF board.

The MDF board contained 14% solid resin / atro fibers and 0.5% solid wax / atro fibers.

Table 2:

Urea-formaldehyde resin, 68% 100.0 g

Paraffin emulsion, 60% 3.2 g

Water 11, 8 g

Example 6:

In each case 70 g of wood fibers from Example 3 were well mixed with 13.2 g of a powdery composition according to Example P2 to P6 of WO 01/27198. 14 g of water were then sprayed onto this fiber-binder mixture with continued mixing. The glued fibers were scattered x 19 cm fiber mat at 70 ⁰ C to a residual moisture of 10% and dried absolutely to a nineteenth

These fiber mats were pressed with a hydraulic press (manufacturer Fa Wickert Maschinenbau GmbH, Landau, model WKP 600 / 3.5 / 3) at a press temperature of 220 ⁰ C for 120 sec between two metal plates with 2 mm spacers. For this purpose, a press pressure of 50 bar was initially set for 20 seconds. Then, after a 10 sec sustained depressurization, a pressure of 200 bar was maintained for a further 90 sec.

The resulting fiberboards were stored for 24 h in a standard atmosphere at 23 ⁰ C and 65% relative humidity and then tested. The water absorption was determined by the weight gain (in%, based on the original weight). The thickness swelling of the wood fiber boards was determined as a relative increase in the thickness of 2 × 2 cm specimens after 24 hours storage in demineralized water analogously to DIN 52351.

Example 7

Wood chips, produced by machining of DMDHEU modified pine boards, prepared according to WO 2004/033170, analogously to Example 2, were analogously to Example 4 with the specified in Table 3 glues at 190 ⁰ C for 230 s to chipboard (density 650 kg / m ³ ). In parallel, unmodified pine wood chips were pressed into chipboard under the same conditions. The particleboard thus prepared was stored in water for 24 hours and the swelling measured as a relative increase in thickness.

1), 4), 5) Aqueous urea resin glues, products of BASF AG, Ludwigshafen

2) glue components related to wood chips (atro)

3) Aqueous melamine resin glue, product of BASF AG, Ludwigshafen

Claims

claims

Use of an aqueous composition containing at least one crosslinkable urea compound selected from urea compounds H, which contains at least one N-linked group of the formula CH ₂ OR, where R is

Hydrogen or C _r C ₄ alkyl, and / or a two nitrogen atoms of the urea bridging 1, 2-bishydroxyethane-1, 2-diyl group, precondensates of the urea compound H, and reaction products or mixtures of the urea compound H with at least one Alcohol selected from C ₁ -C ₆ -alkanols, C ₂ -C ₆ -polyols and oligoethylene glycols for the preparation of lignocellulose-based fine-particle materials treated with this composition for the production of moldings.

2. Use according to claim 1, wherein the crosslinkable urea compound is selected from

1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one,

1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one, which with a

C _r C ₆ -alkanol, a C ₂ -C ₆ -polyol, an oligo- or a polyethylene glycol is modified,

1, 3-bis (hydroxymethyl) urea,

1, 3-bis (methoxymethyl) urea;

1-hydroxymethyl-3-methylurea,

1, 3-bis (hydroxymethyl) imidazolidin-2-one, - 1, 3-bis (hydroxymethyl) -1, 3-hexahydropyrimidin-2-one

1, 3-bis (methoxymethyl) -4,5-dihydroxyimidazolidin-2-one,

Tetra (hydroxymethyl) acetylene diurea.

3. Use according to claim 2, wherein the crosslinkable urea compound 1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one or one with a

C ₁ -C ₆ alkanol is a C ₂ -C ₆ polyoxy, an oligo- or a polyethylene glycol-modified 1, 3-bis (hydroxymethyl) -4,5-dihydroxyimidazolidin-2-one.

Use according to any one of the preceding claims, wherein the concentration of crosslinkable urea compound in the aqueous curable composition is in the range of from 1 to 60% by weight, based on the total weight of the composition.

5. Use according to one of the preceding claims, wherein the aqueous composition contains at least one catalyst which causes the crosslinking of the urea compound.

6. Use according to claim 5, wherein the catalyst K is selected from metal salts from the group of metal halides, metal sulfates, metal nitrates, metal phosphates, metal tetrafluoroborates; boron trifluoride; Ammonium salts from the group of ammonium halides, ammonium sulfate, ammonium oxalate and di-ammonium phosphate; organic carboxylic acids, organic sulfonic acids, boric acid, sulfuric acid and hydrochloric acid.

7. Use according to claim 6, wherein the catalyst K is magnesium chloride. •

Use according to any one of claims 5 to 7, wherein the concentration of the catalyst in the aqueous composition is in the range of 0.1 to

20 wt .-%, based on the total weight of the composition.

9. A process for the production of moldings from finely divided materials based on lignocellulose, comprising

i) providing a lignocellulose-based finely divided material treated with a curable, aqueous composition, wherein the curable, aqueous composition contains:

a) at least one crosslinkable urea compound from the group of the urea compounds H, which is at least one N-bonded group of the formula CH ₂ OR, wherein R is hydrogen or C ₁ -C ₄ -AIlCyI, and / or a bridging the two nitrogen atoms of the urea 1, 2-bishydroxyethane-1,2-diyl group, precondensates of the urea compound H, and reaction products or mixtures of the urea compound H with at least one alcohol which is C _r C ₆ alkanols, C ₂ -C _β polyols and Oligoethylengly - kolen is selected, and

b) at least one of the crosslinking of the urea compound causing catalyst K;

ii) gluing the finely divided material obtained in step i) on the basis of

Lignocellulose or a mixture thereof with other particulate materials with a liquid or powdered preparation of a binder; and

iii) shaping and hardening the glued finely divided material into one

Moldings, or

ii ') mixing the treated finely divided material based on lignocellulose obtained in step i) with a thermoplastic polymer and

iii ') molding the mixture into a shaped article.

A process according to claim 9, wherein the treated lignocellulose-based material is prepared by adding an untreated, finely divided material

Base of lignocellulose impregnated with the aqueous composition and optionally performs a drying and / or curing at elevated temperature.

11. The method of claim 9 or 10, wherein the finely divided material before gluing in step ii) to a residual moisture of less than 30%, based on the dry mass, is dried.

12. The method of claim 10 or 11, wherein the drying and / or curing at temperatures ranging from 50 to 220 ⁰ C is carried out.

13. The method of claim 9, wherein in step i) a treated finely divided material based on lignocellulose is prepared by impregnation with the curable, aqueous composition and the substantially non-hardened material in step ii) glues.

14. The method according to any one of claims 9 to 13, wherein the curable, aqueous composition is used in an amount such that the curable constituents taken up by the finely divided material in the range of 1 to 60 wt .-%, based on the dry mass of the untreated, amount of finely divided material.

15. The method according to any one of claims 9 to 14, wherein the untreated finely divided material based on lignocellulose among wood fibers, wood shavings and wood chips is selected.

16. The method according to any one of claims 9 to 15, wherein the finely divided material based on lignocellulose at least 80 wt .-%, based on the total weight of the molding forming finely divided materials.

17. The method according to any one of claims 9 to 16, wherein the binder used in step ii) comprises at least one thermally curable binder.

18. The method according to claim 17, wherein the thermally curable binder is used in the form of an aqueous preparation.

19. The method according to any one of claims 17 or 18, wherein the thermally curable binder is selected from aminoplast resins, phenolic resins, Isocyanathar- zen and polycarboxylic.

20. The method according to any one of claims 9 to 19, wherein the binder, based on the solid binder components in an amount of 0.5 to 20% by weight, based on the total weight of the molding materials forming materials used.

21. The method according to any one of claims 9 to 15, wherein in step i) performs a drying and curing step and mixes the thus obtainable finely divided material with at least one thermoplastic polymer and subjects the mixture to a molding process.

22. The method of claim 21, wherein the thermoplastic polymer is 20 bis

90 wt .-%, based on the total amount of thermoplastic polymer and molded body, makes up.

23. The method of claim 21 or 22, wherein the thermoplastic polymer is selected from poly-C ₂ -C ₆ -olefins, poly-C ₂ -C ₄ -halo-olefins and mixtures thereof.

24 molded articles of finely divided materials based on lignocellulose, obtainable by a process according to one of claims 9 to 23.

25. A lignocellulose-based finely divided material obtainable by treating an untreated lignocellulose-based particulate material with an aqueous composition, or by impregnating a wood body with a curable, aqueous composition comprising:

a) at least one crosslinkable urea compound from the group of

Urea compounds H, which is at least one N-bonded group of the formula CH ₂ OR, in which R is hydrogen or C _r C ₄ alkyl, and / or a bridging the two nitrogen atoms of the urea 1, 2-bishydroxyethane-1, 2-diyl group, precondensates of the urea compound H, and reaction products or mixtures of the urea compound H with at least one alcohol which is C _r C ₆ alkanols, C ₂ -C ₆ polyols and oligoethylene glycols, and optionally

at least one catalyst which effects crosslinking of the urea compound.