WO2008129056A1

WO2008129056A1 - Wood materials based on polyamine-containing binding agents

Info

Publication number: WO2008129056A1
Application number: PCT/EP2008/054904
Authority: WO
Inventors: Daniel KÄSMAYR; Stephan WEINKÖTZ
Original assignee: Basf Se
Priority date: 2007-04-24
Filing date: 2008-04-23
Publication date: 2008-10-30

Abstract

The invention describes a method for the production of wood materials, wherein wood particles are glued with an aqueous glue solution and are subsequently compressed into the wood material at an elevated temperature, and wherein the glue solution contains, in addition to a polyamine-containing component, a cross-linker with at least two primary alcohol groups.

Description

Wood-based materials based on polyamine-containing binders

description

The invention relates to a process for the production of wood-based materials containing a binder based on polyamines or polyamine-containing aminoplast resins, wood-based materials obtainable by this process, and special polyamine-containing binders.

Wood materials in the context of the invention are materials which are produced by mixing wood particles, for example fibers, chips, strips and wood layers of different thickness, with a binder and subsequent hot pressing.

Typical examples of such materials are wood fiber materials such as medium density fiberboard (MDF), chipboard materials such as chipboard and oriented strand board (OSB), plywood such as veneered plywood, and laminated wood.

The binders used are mainly amino resins, in particular melamine-reinforced urea-formaldehyde condensates (mUF resin), phenolic resins and binders based on isocyanates, in particular of polymeric methylene diisocyanate.

However, since the demands on modern wood-based materials - and thus also the binders used therein - are constantly increasing in terms of application properties as well as economic and ecological aspects, such as the moisture resistance, the processing speed, which must withstand the binder, or the release of harmful substances , Especially of formaldehyde, from the finished material, there is a constant need for new binders that have at least in some areas, preferably in the release of formaldehyde, over the known binders.

Polyamines in conjunction with sugars and a crosslinker from the group of dicarboxylic acids, aldehydes and epoxides as binders for the production of particle board are described in DE-A 43 080 89 and US Pat. No. 3,642,671. WO 01/05891 discloses polyamine-based binders for the production of MDF boards.

It has now been found that the properties of wood-based materials which contain polyamine-based binders can advantageously be modified if the binder additionally contains a crosslinker which contains at least two primary alcohol groups (-CH ₂ OH). The invention therefore provides a process for the production of wood-based materials, wherein

(A) gluing wood particles with an aqueous glue solution, wherein the glue solution contains a binder (L) comprising the following components:

(a-1) an aliphatic polyamine having at least three groups selected from the group of primary and secondary amino groups which has a weight-average molecular weight of 600 to 1,000,000 g / mol and is substantially free from other functional groups except for tertiary amino groups (Polyamine P); and or

(a-2) an aminoplast resin, which is available from

(a-21) formaldehyde;

(a-22) a compound (a-22) selected from the group consisting of urea and melamine, wherein the ratio of the amino groups of the compound (a-22) to the formaldehyde is 0.3: 1 to 3.0: 1;

(a-23) a polyamine P, wherein the molar ratio of the sum of the primary, secondary and tertiary amino groups of the polyamine P to the sum of the primary amino groups of the compounds düng (a-22) 0.0005: 1 to 2: 1;

(a-24) optionally up to 0.2 moles per mole of formaldehyde of another compound (a-24) capable of reacting with formaldehyde in a polycondensation reaction; and

(a-25) optionally up to 0.2 mol per mol of amino groups of the compound (a-22) of another compound (a-25) capable of reacting with amino groups in a polycondensation reaction;

(b) a crosslinker (V) containing two or more primary alcohol groups, and

(c) optionally an aminoplast resin, which is obtainable from

(c-1) formaldehyde; (c-2) a compound (c-2) selected from the group consisting of urea and melamine, wherein the ratio of the amino groups of the compound (c-2) to the formaldehyde is 0.3: 1 to 3: 1;

(c-3) and optionally up to 0.2 mol per mol of formaldehyde of another compound (c-3) capable of reacting with formaldehyde in a polycondensation reaction;

(C-4) and optionally up to 0.2 mol per mol of amino groups of

Compound (c-2) of another compound (c-4) capable of reacting with amino groups in a polycondensation reaction;

(B) the glued wood particles obtained according to step (A) pressed at elevated temperature to a wood material.

The invention furthermore relates to wood-based materials obtainable, preferably obtained, by the process according to the invention.

Likewise provided by the invention is the binder (L) according to the invention and its use as a binder for wood-based materials.

Wood-based materials according to the invention are characterized by better mechanical properties, less swelling due to contact with water, lower emissions of formaldehyde and shorter pressing times.

The term wood particles within the meaning of the invention comprises the comminuted and processed wood parts commonly used for the production of the desired wood materials (such as MDF boards and chipboard), for example wood layers, wood strips, wood chips or wood fibers, the latter optionally also of wood fiber-containing plants such as flax, hemp , Sunflowers, Jerusalem artichoke or canola.

Starting materials for wood particles are usually thinning, industrial waste and used wood as well as wood fiber containing plants.

Their preparation for the respective desired wood particles is carried out by known methods known to those skilled in the art, as described for example in M. Dunky, P. Niemt, Holwerkstoffe and Glues, pp. 91-156, Springer Verlag Heidelberg, 2002. Thus, for example, for the production of MDF boards such cellulosic fibers into consideration, which are commonly used for the production of MDF into consideration. Such raw materials are described, for example, in "MDF Medium Density Fiberboard", Hans-Joachim Deppe, Kurt Ernst, 1996, DRW-Verlag Weinbrenner GmbH & Co., 70771 Leinfelden-Echterdingen, Chapter 2, pages 25 ff Annual plants, waste paper fiber material and preferably wood fibers.

As the sizing solution (L-1), preferred is a solution containing the components (a-1) and (b).

Further preferred is a sizing solution (L-2) containing the component (a-1), (b) and (c).

Further preferred is a sizing solution (L-3) containing the component (a-2) and (b).

Further preferred is a sizing solution (L-4) containing the component (a-1), (a-2), and (b).

Further preferred is a sizing solution (L-5) containing the component (a-1), (a-2), (b) and (C).

Further preferred is a sizing solution (L-6) containing the component (a-2), (b) and (c).

Particularly preferred are the sizing solutions (L-1), (L-2), (L-3) and (L-4).

Most preferred are the size solutions (L-1), (L-2) and (L-3).

Particularly preferred are the sizing solutions (L-1) and (L-2).

The polyamine (P) component (a-1) is an aqueous solution of an aliphatic polyamine having at least 3 functional groups selected from the group of primary and secondary amino groups and having a weight-average molecular weight of 600 to 1,000. 000 g / mol and, apart from tertiary amino groups is substantially free of other functional groups. Essentially free in the sense of the invention means, in particular, that in the case of polyvinylamine partial hydrolysates are included, which may still contain up to about 10% formamide groups or other functions. As components (a-1) it is preferred to use polyamines which have a molecular weight of at least 500 g / mol and at least 10 primary or secondary amino groups. Preferred polyamines are poly (ethyleneimine) and poly (vinylamine).

The weight-average molecular weight of the polyvinylamine is preferably 5,000 to 250,000 g / mol, more preferably 5,000 to 100,000 g / mol, that of the polyethyleneimine is preferably 500 to 200,000 g / mol, more preferably 800 to 70,000 g / mol, most preferably 2,000 to 50,000 g / mol and in particular 5,000 to 50,000 g / mol.

The component (a-1) - if present - contains one or more, preferably one or two, more preferably a polyamine (P).

Component (a-2) is an aminoplast resin which is available from:

(a-21) formaldehyde;

(a-22) a compound (a-22) selected from the group consisting of urea and melamine, wherein the ratio of the amino groups of the compounds (a-22) to the formaldehyde is 0.3: 1 to 3.0: 1;

(a-23) a polyamine P, wherein the molar ratio of the sum of the primary, secondary and tertiary amino groups of the polyamine P to the sum of the primary amino groups of the compound (a-22) is 0.0005: 1 to 2000: 1;

(a-24) optionally up to 0.4 mole per mole of formaldehyde of another compound (a-24) capable of reacting with formaldehyde in a polycondensation reaction; and

(a-25) optionally up to 0.4 mole per mole of amino groups of the compound (a-22) of another compound (a-25) capable of reacting as an electrophile with amino groups;

The compounds (a-24) are, for example, guanidines, thiourea or alkali hydrogen sulphite or alkali metal sulphite.

The compounds (a-25) are, for example, carboxylic acids or carboxylic anhydrides, preferably C 1 -C 10 -mono- or di- or polycarboxylic acids or anhydrides, in particular maleic anhydride, succinic anhydride or phthalic anhydride, organic halogen compounds such as Cr to C ₁ 0-alkyl halides, isocyanates, such as are generally known for preparing polyurethanes, for example, hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI) and polymethylene polyisocyanates (PMDI) , Aldehydes, in particular aliphatic d- to Ci ₀ - mono- or dialdehydes, such as succinaldehyde, glutaraldehyde or acetaldehyde, chlorohydrins, in particular epichlorohydrin, or epoxides derived from these chlorohydrins.

The aminoplast resins (a-2), in addition to the fact that a polyamine (P) is additionally used, prepared in principle by generally known methods, as described in Ullmann's Encyclopedia of Industrial Chemistry, 1996, VCH Verlagsgesellschaft, Vol. A2, chapter "Amino Resins ", pages 1 to 15 et seq., And WO 01/05891 The preparation of polyamine-modified urea-formaldehyde resins is described in Journal of Applied Polymer Science, 47 (1991) 2957.

In general, one proceeds in such a way that one

in step 1, an aqueous solution of

Formaldehyde; such amounts of the compound (a-22) that the ratio of the amino groups of the compound (a-22) to the formaldehyde is 0.1: 1 to 2.0: 1; - such amounts of the polyamine (P) that the molar ratio of the sum of the primary, secondary and tertiary amino groups of the polyamine P to the sum of the primary amino groups of the compound (a-22) is 0.0005: 1 to 2000: 1; optionally up to 0.2 mol per mol of formaldehyde of another compound (a-24); and optionally in amounts up to 0.2 mol per mol of amino groups of the compound (a-25);

at a pH of 2.5 to 8.5, preferably at pH 4.0 to 6.5, and a temperature of 50 to 100 ⁰ C until such time as the solution has a viscosity of

10 to 2,000 mPas, and

in step 2, if necessary, raising the pH to 6 to 9 and, if necessary, adding such amounts of urea that the final molar ratio of the components (a-21), (a-22), (a-) 23) and (a-24) is reached, and the reaction mixture further reacted at a temperature of 20 to 100 ⁰ C until the solution has a viscosity of 10 to 2,000 mPas.

The information on the viscosity refers to samples which were measured at 20 ^° C. and adjusted to a solids content of 40% by weight before the measurement.

The component (a-2), if present, contains one or more, preferably one or two, more preferably a modified aminoplast resin.

The crosslinker component (b) contains one or more, preferably one or two, particularly preferably one, low molecular weight, oligomeric or polymeric crosslinker (V) which contains two or more primary hydroxyl groups.

Examples of crosslinkers (V) are

V-1 aliphatic di- or polyols of the formula (I),

HO-CH ₂ -R ¹ -CH ₂ -OH (I),

wherein R ^{1 is} a straight-chain, branched or cyclic alkylene group having 1 to 10

C atoms which is unsubstituted or substituted by one or more CH ₂ -OH groups.

Preferred examples are ethanediol (glycol), 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, trimethylolmethane, trimethylolethane, trimethylolpropane, (2,2-bis-hydroxymethyl-1 butanol), pentaerythritol (2,2-bis-hydroxymethyl-1-butanol) and 1,1,2,2-tetramethylolethane.

V-2 sugar alcohols (alditols), in particular of the formula (II),

HIGH ₂ - (CHOH) _n -CH ₂ OH (II)

where n is a natural number from 1 to 4, for example glycerol, tetrides, such as threitol and erythritol, pentides, such as ribitol, adonite, arabitol and XyNt, and hexitols, such as dulcitol, mannitol and sorbitol.

V-3 acyclic and cyclic bis- and oligomethylol-urea derivatives, preferably of the formula (III), O

HO (H ₂ C) _n -N CN - (CH ₂ ) _n OH

R ² R ³

^KK (III),

in which

R ² , R ^{3 are} identical or different H, (C _r C ₆ ) alkyl or (CH ₂ ) _n OH

or

R ² and R ³ together - (CH ₂ ) _m -, - (CHR ') _m - (with R' = H or OH), -CH ₂ -NR ⁴ -CH ₂ -, -CO-NR ⁴ -CO- (with R ⁴ = CH ₃ , C ₂ H ₅ , CH ₂ OH or CH ₂ -CH ₂ -OH);

m is 2 or 3, preferably 2, and

n is 1 or 2, preferably 1,

mean.

Examples are 1, 3-dimethylol-4,5-dihydroxyethyleneurea (4,5-dihydroxy-1,3-bis (hydroxymethyl) imidazolidin-2-one), dimethylolethyleneurea (1,3-bis (hydroxymethyl) imidazolidin-2-one) on), di- and trimethyloltriazinones, such as 5-methyl

1, 3-bis (hydroxymethyl) triazinone and 1, 3,5-tris (hydroxymethyl) triazinone.

(Hydroxyalkyl) aminoalkyl compounds of the formula (IV),

HO (CH ₂ ) _n

HO (CH ₂ ) _n C- (CH ₂ ) _m -NH ₂

^R (IV)

With R = H, (C ₁ -Ce) alkyl, (CH ₂ ) _n -OH;

m = 0, 1 or 2; and

n = 1 or 2;

for example trometamol (m = 0 and n = 1).

V-5 bis- or polyhydroxymethylated melamine derivatives of the formula (V),

in which

R ^{5 is the} same or different H or - (CH ₂ ) _n OR ';

R 'is H or (C _r C ₄ ) alkyl;

n is 1, 2, 3 or 4, preferably 1 or 2, more preferably 1,

means;

for example hexamethylolmelamine (R ⁵ = CH ₂ OH).

V-6 polyalkylene glycols, preferably those of the formula (VI),

H- (E) ₃ -OH (VI),

in which

E is identical or different and is 0-CH ₂ -CH ₂ or 0-CH ₂ -CH (CH ₃ ) - and

3 <s <100 applies. The compounds may be random, alternating or block copolymers in the case of copolymers. Preferably, a molecular weight M _w of 80 to 10,000. Particularly preferred is polyethylene glycol, in particular with a molecular weight of 80 to 2,000.

V-7 polyoxymethylenes with uncapped end groups and a molecular weight M _w in the range of 80 to 10,000, preferably 80 to 2,000.

V-8 phenol-formaldehyde condensates from the group of resoles.

Resole resins of the types which are also used as binders in the production of wood-based materials are preferred, ie. H. Resoles obtainable by base catalyzed condensation of (optionally modified) phenol and formaldehyde in a molar ratio of 1: 1, 5 to 1: 1, 25. Preferably, such a resol is used as an aqueous alkaline solution having an alkali content of 3-10%.

The crosslinkers V-1 to V-8 mentioned are known and either commercially available or can be prepared by known methods known to the person skilled in the art.

(V-1): Aliphatic di- or polyols of the formula (I) (V-1) and their preparation are described, for example, in Houben Weyl, Methods of Organic Chemistry and are commercially available from BASF SE, Ludwigshafen, Germany.

(V-2): Sugar alcohols and their preparation are described, for example, in Römpp Chemie Lexikon, Vol. 6, 9th ed., C. Thieme Verlag, Stuttgart 1995 and the literature cited therein. Such compounds are sold, for example, as food additives.

(V-3): Methylol ureas and their preparation are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry. Derivatives of these compounds are marketed, for example, by BASF SE under the name Fixapret® crosslinking agents for textile production and processing.

(V-4): Tris (hydroxymethyl) aminoalkyl compounds and their preparation are described, for example, in Römpp Chemie Lexikon (supra) and the references cited therein.

(V-5): Melamine derivatives of the formula (V) and their preparation are described, for example, in Römpp Chemie Lexikon (see above) and the literature cited therein. sol che connections are still available under the name Luwipal® ^® from BASF SE.

(V-6): polyalkylene glycols and their preparation are, for example, in Römpp Chemie Lexikon (see above) and described in the literature cited therein, and are typically sold by BASF under the name SE Pluriol ^®.

(V-7): Polyoxymethylenes and their preparation are described, for example, in Römpp Chemie Lexikon (supra) and references cited therein, and are described i.a. from Ticino (Kelsterbach, Germany).

(V-8): Resole resins and their preparation are described, for example, under the heading phenolic resins in Ullmann's Encyclopedia of Industrial Chemistry and the literature cited therein, and can be obtained, for example, from Hexion AG (Iserlohn, Germany).

The optionally contained aminoplast resin (c) is available from

(c-1) formaldehyde;

(c-2) a compound (c-2) selected from the group consisting of urea and

Melamine, wherein the ratio of the amino groups of the compound (c-2) to

Formaldehyde is 0.3: 1 to 3: 1;

(c-4) and optionally up to 0.2 mol per mol of amino groups of the compound (c-2) of another compound (c-4) capable of reacting with amino groups as electrophiles;

Such size resins (c) are generally known and described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 1996, VCH Verlagsgesellschaft, Vol. A2, Chapter "Amino Resins", page 115 et seq.

As the compounds (c-3), the same are considered as compounds (a-24), as compounds (c-4) the same as compounds (a-25).

The aminoplast resins (c) are basically made in the same way as the aminoplast resins (a2), except that no polyamine (P) is used. The glue solutions according to the invention may furthermore contain customary auxiliaries, such as water repellents, for example paraffins, or wood preservatives. Furthermore, the glue solutions can be mixed with a hardener, for example a carboxylic acid, such as formic acid or an ammonium salt, immediately before processing in order to shorten the curing times.

The solids content of the glue solutions is usually determined by pouring a defined amount by weight (about 2 g) of the appropriate solution onto a tray and drying for 2 hours at 120 ⁰ C in a drying oven. The solids content is determined by differential weighing.

The sizing solution (L) generally contains 0 to 80 wt .-% (based on the binder) of polyamine (a-1), preferably 10 to 50 wt .-%, particularly preferably 20 to 40 wt .-%.

The content of the polyaminomodified aminoplast component (a-2) is generally 0 to 80 wt .-%, preferably 0 to 50 wt .-%, particularly preferably 0 to 25 wt .-%.

The content of crosslinker (V) in the size-reducing solution according to the invention is generally from 1 to 30% by weight, preferably from 2 to 30% by weight, particularly preferably from 3 to 10% by weight.

The content of the aminoplast resin (C) is generally 0 to 80 wt .-%, preferably 0 to 50 wt .-%, particularly preferably 0 to 25 wt .-%.

The content of additives is generally 0 to 5 wt .-%.

The amount of water in wt .-% (based on atro wood particles) is preferably 1 to 150%, more preferably 2 to 120%.

The amount of the amine component ((a-1) and / or (a-2) and optionally (c)) based on atro wood particles is generally 0.1 to 15 wt .-%.

The amount of crosslinker based on the amine component is generally from 5 to 100 wt .-%, preferably 5 to 50 wt .-% and particularly preferably 10 to 25 wt .-%.

In the sizing solution (L-2), the weight ratio of components (a-1) :( c) is generally 1-10: 10-1. In the sizing solution (L-4), the weight ratio of components (a-1): (a-2) is generally 1-10: 10-1.

In the sizing solution (L-5), the weight ratio of components (a-1): (a-2) is generally 1-10: 10-1 and the weight ratio of component a ((a-1) + (a-2 )): (c) generally 1-10: 10-1.

For carrying out the process according to the invention, the moisture of the wood particles or the water content of the glue is preferably adjusted in step A such that the moisture of the glued wood particles is not more than 150%, preferably 2 to 120%.

Further preferred is a separate addition of polyamine component (a) and crosslinker component (b), wherein preferably the polyamine component (a) is initially charged and the crosslinker component (b) is then added, more preferably only immediately before the pressing operation in step (B) Of course, a sufficient mixing of the components must take place before the pressing process.

The gluing of the wood particles in step A takes place according to the methods and conditions which are appropriate for the respective type of wood particles and which are familiar to the person skilled in the art. For example, in the production of MDF boards, the gluing can be done by mixer gluing, blow-line gluing or dry gluing.

In order to avoid a premature reaction of binder and crosslinking agent, the loading is sizing at low temperatures, preferably carried out from 20 to 40 ⁰ C.

The gluing of the glued wood particles in step B is carried out according to the conditions appropriate for the respective wood material, as known to those skilled in the art and described for example under the keyword "Wood" in Ullmann's' Encyclopedia of Industrial Chemistry and the literature cited therein.

The temperature during pressing (based on the pressure plate) is generally from 150 ⁰ C to 250 ⁰ C, preferably 200 ⁰ C to 240 ⁰ C, the temperature in the middle of the plate for plates with a thickness of> 5 mm is not more than 150 ^0th C rises and is about 110 ⁰ C in the middle of the plate with conventional chipboard (16 mm). The pressure is generally 1 to 5 N / mm ² . The pressing times are generally from 2 to 30 s / mm, preferably from 5 to 15 s / mm.

In addition to the production of chipboard and OSB boards, the production of MDF boards by the process according to the invention is preferred. According to the invention, the size solutions for producing the MDF boards are applied to the cellulosic fibers by conventional methods (see "MDF - Medium Density Fiberboard", Hans-Joachim Deppe, Kurt Ernst, 1996, DRW-Verlag Weinbringer GmbH & Co., 70771 Leinfelden-Echterdingen, chapter 4.3, pages 81 ff.) -

Usually, one proceeds by gluing cellulosic fibers having a moisture content of 0 to 120% in a so-called blowline, ie, by vortexing the fibers in an air or steam stream and spraying the glue solution or gluing by mixing fibers and glue solution in a trough mixer makes. Moisture is defined as the ratio of the difference between the actual weight of the wood and the corresponding weight of atro (absolutely dry) fibers to the weight of atro fibers. The weight of the absolutely dry fibers is determined by drying a certain amount of fibers in a drying cabinet at 105 ⁰ C for 16 hours.

Optionally follows, in particular for MDF boards, a drying step to adjust a fiber moisture content of 5 to 15%.

Subsequently, the glued cellulosic fibers are pressed by a conventional method to fiberboard. For this purpose, for example, by sprinkling the glued cellulosic fibers on a support a fiber mat and squeezed them at temperatures of 80 to 250 ⁰ C and at pressures of 5 to 50 bar to fiberboard (see loc. Cit., Chapter 4.5, pages 93ff).

Preferably, the glued cellulosic fibers are scattered to fiber mats of such a layer thickness that result after hot pressing fiberboard with a density of 500 to 900 kg / m3 and a layer thickness of 3 to 40, preferably 3 to 25 mm. The pressing times required for this purpose are usually 3 to 20 seconds per mm thickness of the resulting fiberboard.

In order to produce fiberboard with smooth surfaces, suitable as smooth surface press tools, e.g. two polished steel belts, one of which serves as a support for the fiber mat, or a combination of a polished steel belt as a support and an over-running polished steel roller or a combination of several polished steel rollers.

According to the invention thus MDF boards can be produced, as required in particular by the furniture industry and the

are highly densified so that they have good mechanical properties, about 6 to 40 mm thick, so that they are used for the production of furniture side panels or doors, and have a smooth surface on both sides. Such plates are referred to as S2S plates (smooth-two sides) (see Ullmann's Encyclopedia of Industrial Chemistry, 1996 VCH Verlagsgesellschaft, Vol. A 28, Chapter 2.3.2.1, page 336).

The obtained wood materials, especially MDF boards, chipboard and OSB boards can be processed as usual and are particularly suitable for the production of furniture parts.

Claims

claims

1. A process for the production of wood-based materials, wherein one

(a-1) an aliphatic polyamine having at least three groups selected from the group of primary and secondary amino groups, which has a weight average molecular weight of 600 to 1,000,000 g / mol and, apart from tertiary amino groups, substantially free from other functional groups Groups is (polyamine P); and or

(a-2) an aminoplast resin, which is available from

(a-21) formaldehyde;

(a-22) a compound (a-22) selected from the group consisting of urea and melamine, wherein the ratio of the amino groups of the compound (a-22) to the formaldehyde is 0.3: 1 to 3.0: 1 ;

(a-23) a polyamine P, wherein the molar ratio of the sum of the primary, secondary and tertiary amino groups of the polyamine P to the sum of the primary amino groups of the compound (a-22) is 0.0005: 1 to 2: 1;

(b) a crosslinker (V) containing two or more primary alcohol groups, and (c) optionally an aminoplast resin, which is obtainable from

(c-1) formaldehyde;

(c-2) a compound (c-2) selected from the group consisting of urea and melamine, wherein the ratio of the amino groups of the compound (c-2) to the formaldehyde is 0.4: 1 to 3: 1;

(c-4) and optionally up to 0.2 mol per mol of amino groups of the compound (c-2) of another compound (c-4) capable of reacting with amino groups in a polycondensation reaction; and

(B) the glued wood particles obtained according to step (A) at an elevated temperature to a wood material pressed.

2. The method according to claim 1, wherein as the size solution, a sizing solution (L-1) containing the components (a-1) and (b), a sizing solution (L-2) containing the component (a-1), (b ) and (c) a sizing solution (L-3) containing the components (a-2) and (b), a sizing solution (L-4) containing the component (a-1), (a-2) and (b) a sizing solution (L-5) containing the component (a-1), (a-2), (b) and (c), or a sizing solution (L-6) containing the component (a- 2), (b) and (c) is used.

3. The method according to claim 2, wherein a sizing solution (L-1), (L-2) or (L-3) is used.

4. The method according to any one of claims 1 to 3, wherein it is the polyamine (P) is polyethyleneimine or polyvinylamine.

The process of claim 4 wherein the polyethylenimine has a weight average molecular weight of 500 to 200,000 and the polyvinylamine has one of 5,000 to 200,000.

6. The method according to any one of claims 1 to 5, wherein the crosslinking component (b) is selected from:

V-1 aliphatic di- or polyols of the formula (I),

HO-CH ₂ -R ¹ -CH ₂ -OH (I),

wherein R ^{1 represents} a straight-chain, branched or cyclic alkylene group having 1 to 10 C atoms, which is unsubstituted or substituted by one or more CH ₂ -OH groups;

V-2 sugar alcohols (alditols) of the formula (II),

HIGH ₂ - (CHOH) _n -CH ₂ OH (II)

where n is a natural number from 1 to 4;

V-3 acyclic and cyclic bis- and oligomethylol-urea derivatives;

V-4 (hydroxyalkyl) aminoalkyl compounds of the formula (IV)

HO (CH ₂ ) _n

HO (CH ₉ )

; C- (CH ₂ ) _m -NH ₂

R (IV)

With

R = H, (C 1 -C 6 -alkyl, (CH 3 -OH;

m = 0, 1 or 2; and

n = 1 or 2;

V-5 bis- or polyhydroxymethylated melamine derivatives of the formula (V),

in which

R ^{5 is the} same or different H or - (CH ₂ ) _n OR ';

R 'is H or (C _r C ₄ ) alkyl;

N 1, 2, 3 or 4,

means;

V-6 polyalkylene glycols;

V-7 polyoxymethylenes with uncapped end groups and one molecular weight

_Mw in the range of 80 to 10,000, and

V-8 phenol-formaldehyde condensates from the group of resoles

7. The method according to claim 6, wherein as component V-6 polyalkylene glycols of the formula (VI),

H- (E) ₃ -OH (VI), where

3 <s <100, are used.

8. The method according to any one of claims 1 to 7, wherein the aqueous glue solution further contains a hydrophobing agent.

9. wood material, obtainable by a process according to any one of claims 1 to 8.

10. A binder according to any one of claims 1 to 8.

1 1. Use of the binder according to any one of claims 1 to 8 as a binder for wood-based materials.