WO2003000761A1

WO2003000761A1 - Coated medium-density fibre boards, method for production and use thereof

Info

Publication number: WO2003000761A1
Application number: PCT/EP2002/006677
Authority: WO
Inventors: Wolfgang Bremser; Hans-Peter Steiner; Frank Strickmann; Peter-Eduard Kunze
Original assignee: Basf Coatings Ag
Priority date: 2001-06-21
Filing date: 2002-06-18
Publication date: 2003-01-03
Also published as: EP1401908A1; DE10129875A1

Abstract

Medium-density fibre boards, coated on at least one surface thereof, whereby the coating may be produced by applying at least one coating material to the surfaces and hardening the resultant layer(s). At least one of the coating materials contains (A) the aqueous dispersion of a block co-polymer, comprising isocyanate-reactive functional groups obtained by the twin- or multiple-stage controlled radical block co-polymerisation in an aqueous or organic medium, whereby (1) in a first stage (a) at least one olefinic unsaturated monomer and (b) at least one olefinic unsaturated monomer, different from the olefinic unsaturated monomer (a), of general formula (I): R?1R2C=CR3R4¿ are co-polymerised, (2) in a second stage a further monomer (a) is (co-)polymerised in the presence of the co-polymer from the first stage without addition of radical initiators and (B) a polyisocyanate.

Description

Coated medium density fiberboard, process for its production and its use

The present invention relates to new coated mitrichicht fibreboards. The present invention also relates to a new method for producing coated medium-density fiberboard. Furthermore, the present invention relates to the use of the new coated medium-density fiberboard for the production of doors, wooden cassettes, furniture and rear walls of furniture.

Coated medium-density fibreboards and their use for the production of doors, wooden cassettes, furniture and back walls of furniture are known per se. Because of the porous structure of the medium density fiberboard, however, their coating often causes problems. The aim is to produce scratch-resistant, glossy coatings that have a uniform flow and a smooth surface without faults, such as craters or pinholes, are free of light-dark shades (clouds) and against all household chemicals , including active chlorine, are stable. With the coating materials previously used for this purpose, however, it is not easy to produce coatings that easily meet all of these requirements.

Pigmented coating materials are known from German patent applications DE 199 30 665 A 1 and DE 199 30 067 A 1

A) as a binder or as one of the binders at least one copolymer, which by radical polymerization of a) at least one olefinically unsaturated monomer and

b) at least one olefinically unsaturated monomer of the general formula I which is different from the olefinically unsaturated monomer (a)

R ¹ R ² C = CR ³ R ⁴ (I),

wherein the radicals R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen atoms or substituted or unsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl or arylcycloalkyl radicals with the proviso that at least two of the variables R ¹ , R ² , R ³ and R ^{4 are} substituted or unsubstituted aryl, arylalkyl or

Arylcycloalkyl radicals, in particular substituted or unsubstituted aryl radicals;

can be produced in an aqueous medium;

such as

B) at least one color and / or effect pigment and / or at least one filler

contain.

The pigmented coating materials can be two- or multi-component systems which contain polyisocyanates as crosslinking agents. Furthermore, the pigmented coating materials can be customary and known binders, such as linear and / or branched and / or block-like, comb-like and / or random (meth) acrylate (co) polymers, polyesters, alkyds, aminoplast resins, polyurethanes, acrylated polyurethanes, acrylated polyesters , Polylactones, polycarbonates, polyethers, epoxy resin-amine adducts, (meth) acrylate diols, preferably in an amount of 1 to 50, preferably 2 to 40, particularly preferably 3 to 30 and in particular 5 to 25% by weight, in each case based on the total solids content of the coating material. It is not specified which of these customary and known binders are preferably used. In addition, it is not proposed to use the binders in the form of their dispersions.

Suitable substrates are all surfaces to be painted, which are not damaged by curing the paintwork thereon using heat and optionally actinic radiation. B. metals, plastics, wood, ceramics, stone, textiles, fiber composites, leather, glass, glass fibers, glass and rock wool, mineral and resin-bound building materials, such as plaster and cement boards or roof tiles, as well as composites of these materials. However, the fiber composites are not specified in more detail.

The known coating materials are basically also suitable for applications outside of automotive painting, for example in industrial painting, including coil coating and container coating. In the context of industrial painting, they are suitable for painting practically all parts and objects for private or industrial use, such as radiators, household appliances, small parts made of metal, hubcaps or rims. In addition, the Basecoat according to the invention also for painting furniture. But above all, they are used for automotive painting.

The coating of medium density fiberboard and the problems associated with it are not described in the German patent applications.

The object of the present invention is to provide new coated medium-density fiberboard which are suitable for the production of doors in the interior, of wooden cassettes, furniture and furniture rear walls and which have scratch-resistant, glossy coatings which have a uniform flow and a smooth surface without defects, such as Craters or pinholes, have no light-dark shades (clouds) and are resistant to all household chemicals, including those containing active chlorine. In addition, the new coated medium-density fiberboard should be easy to manufacture.

Accordingly, we have found the new medium-density fiberboard which is coated on at least one of its surfaces, the coating being producible by applying at least one coating material to at least one surface and curing the resulting layer or layers, at least one of the coating materials

(A) the aqueous dispersion of at least one block copolymer, which on average has at least two isocyanate-reactive functional groups and by the two-stage or multistage, controlled radical block copolymerization in is available in an aqueous or an organic medium, wherein

(1) in a first stage

(a) at least one olefinically unsaturated monomer and

(b) at least one olefinically unsaturated monomer of the general formula I which is different from the olefinically unsaturated monomer (a)

R ¹ R ² C = CR ³ R ⁴ (I),

wherein the radicals R ¹ , R ² , R ³ and R ^{4 are} each independently of one another hydrogen atoms or substituted or unsubstituted alkyl, cycloalkyl,

Alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl or arylcycloalkyl radicals, with the proviso that at least two of the variables R ¹ , R ² , R ³ and R ^{4 are} substituted or unsubstituted aryl, arylalkyl or

copolymerized, after which

(2) in a second stage, at least one further monomer (a) is polymerized in the presence of the copolymer formed in the first stage without the addition of free radical initiators (co); and

(B) at least one crosslinking agent component with at least one polyisocyanate

contains.

In view of the prior art, it was surprising and unforeseeable for the person skilled in the art that the object on which the present invention is based, with the aid of the coating materials to be used according to the invention, which comprises an aqueous dispersion (A) of at least one block copolymer of monomers (a ) and (b) could be solved. It was particularly surprising that these coating materials in particular had an application-related property profile which made them outstandingly suitable for coating medium-density fiberboard. As a result, the coating materials on the medium-density fiberboard provided scratch-resistant, glossy coatings, which had a uniform course and a smooth surface without defects, such as craters or pinholes, were free from light-dark shades (clouds) and against all household chemicals , including active chlorine, were stable.

The medium-density fiberboard to be coated is the usual and known medium-density fiberboard, as is known to be used for the production of doors in the interior, wooden cassettes, cheap furniture and furniture back panels. The medium-density fiberboard is coated on at least one surface, in particular at least two surfaces. The two surfaces are preferably the front and the back of the medium-density fiberboard. However, at least one of the four lateral surfaces can also be coated. Which embodiment is chosen depends on the intended use of the new coated medium-density fiberboard.

The coating on at least one of the surfaces can be produced by applying at least one coating material to the surface in question and curing the resulting layer or layers.

Preferably, two coating materials are applied to the surface in question, the first coating material being a customary and known, preferably physically curing, coating material based on organic solvents, in particular methyl ethyl ketone, and (meth) acrylate copolymers as used in the field of medium density Fiberboard is commonly used to make primers. (Meth) acrylate copolymers which are suitable for this purpose are commercially available products and are sold, for example, by DSM under the brand Uracron®, for example Uracron® CY476E.

It is essential that at least one of the further coating materials or the further coating material which is applied to the primer contains the aqueous dispersion (A) of at least one block copolymer. The block copolymer contains on average at least two, preferably at least three, in particular at least four, isocyanate-reactive functional groups. Examples of suitable isocyanate-reactive groups are hydroxyl groups, primary and secondary amino groups (if not neutralized), thiol groups and imino groups. After their neutralization, the primary and secondary amino groups can also serve as dispersing functional groups (ii). Hydroxyl groups are preferably used.

The block copolymer can be prepared by two-stage or multi-stage, in particular two-stage, controlled radical copolymerization of at least one olefinically unsaturated monomer (a) with at least one monomer (b).

The monomers (a) are preferably selected from the group consisting of hydrophilic and hydrophobic olefinically unsaturated monomers. For the terms “hydrophilic” and “hydrophobic”, reference is made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, page 294, “Hydrophilie”, and pages 294 and 295, “Hydrophobie”.

Suitable hydrophilic monomers (a) contain at least one, in particular one, dispersing functional group which consists of the group consisting of

(i) functional groups which can be converted into anions by neutralizing agents and anionic groups,

or (ii) functional groups by neutralizing agents and / or quaternizing agents! can be converted into cations, and cationic groups,

and

(iii) nonionic hydrophilic groups,

is selected.

The functional groups (i) from the group consisting of carboxylic acid, sulfonic acid and phosphonic acid groups, acidic sulfuric acid and phosphoric acid ester groups and carboxylate, sulfonate, phosphonate, sulfate ester and phosphate ester groups are preferably the functional groups (ii) from the Group consisting of primary, secondary and tertiary amino groups, primary, secondary, tertiary and quaternary ammonium groups, quaternary phosphonium groups and tertiary sulfonium groups, and the functional groups (iii) from the group consisting of omega-hydroxy and omega-alkoxy poly ( alky! enoxid) -1-yl groups.

If not neutralized, the primary and secondary amino groups can also serve as isocyanate-reactive functional groups.

Examples of highly suitable hydrophilic monomers (a) with functional groups (i) are acrylic acid, methacrylic acid, beta-carboxyethyl acrylate, ethacrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid; olefinically unsaturated sulfonic or phosphonic acids or their partial esters; or maleic acid mono (meth) acryloyloxyethyl ester, succinic acid mono (meth) acryloyloxyethyl ester or phthalic acid mono no (meth) acryloyloxyethyl ester, especially acrylic acid and methacrylic acid.

Examples of highly suitable hydrophilic monomers (a) with functional groups (ii) are 2-aminoethyl acrylate and methacrylate or allylamine.

Examples of highly suitable hydrophilic monomers (a) with functional groups (iii) are omega-hydroxy or omega-methoxy-polyethylene oxide-1-yl-, omega-methoxy-polypropylene-oxide-1-yl- or omega-methoxy-poly (ethylene oxide) -co-polypropylene oxide) -1 -yl acrylate or methacrylate.

When selecting the hydrophilic monomers (a), care must be taken that the hydrophilic monomers (a) with functional groups (i) and the hydrophilic monomers (a) with functional groups (ii) are not combined with one another, because this is insoluble to form them Salts and polyelectrolyte complexes can lead. In contrast, the hydrophilic monomers (a) with functional groups (i) or with functional groups (ii) with the hydrophilic monomers (a) with functional groups (iii) can be combined as desired.

Of the hydrophilic monomers (a) described above, the monomers (a) with the functional groups (i) are particularly preferably used.

The neutralizing agents for the functional groups (i) which can be converted into anions are preferably selected from the group consisting of ammonia, trimethylamine, triethylamine, tributylamine, dimethylaniline, diethylaniline, triphenylamine, dimethylethanolamine, diethylethanolamine, methyldiethanolamine, 2-aminomethylpropanol, dimethylisopropylamine, dimethylisopropylamine, dimethylisopropylamine , Diethylenetriamine and Triethylenetetramine, and the neutralizing agents for the functional groups convertible into cations (ii) selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, lactic acid, dimethylolpropionic acid and citric acid.

Examples of suitable hydrophobic olefinically unsaturated monomers (a) are

(1) ~ essentially acid group-free esters of olefinically unsaturated acids, such as (meth) acrylic acid, crotonic acid, ethacrylic acid, vinylphosphonic acid or vinylsulfonic acid alkyl or cycloalkyl esters with up to 20 carbon atoms in the alkyl radical, in particular methyl, ethyl, propyl, n-butyl, sec.-butyl, tert-butyl, hexyl, ethylhexyl, stearyl and lauryl acrylate, methacrylate,

-crotonate, -ethacrylate or -vinylphosphonate or vinyl sulfonate; Cycloaliphatic (meth) acrylic acid, crotonic acid, ethacrylic acid, vinylphosphonic acid or vinylsulfonic acid esters, especially cyclohexyl, isobornyl, dicyclopentadienyl, octahydro-4,7-methano-1H-indene-methanol or tert.-

Butylcyclohexyl (meth) acrylate, crotonate, ethacrylate, vinyl phosphonate or vinyl sulfonate. These can be used in minor amounts of higher-functional (meth) acrylic acid, crotonic acid or alkyl or cycloalkyl ethacrylic acid, such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol,

Butylene glycol, pentane-1, 5-diol, hexane-1,6-diol, octahydro-4,7-methano-1H-indene-dimethanol- or cyclohexane-1, 2-, -1,3- or - 1,4-diol-di (meth) acrylate; Trimethylolpropane tri (meth) acrylate; or pentaerythritol tetra (meth) acrylate and the analog ethacrylates or crotonates. Within the scope of the present invention minor amounts of higher-functional monomers (1) are to be understood here as amounts which do not lead to crosslinking or gelling of the block copolymers, unless they should be in the form of crosslinked microgel particles;

(2) monomers which carry at least one hydroxyl group or hydroxymethylamino group per molecule and are essentially free of acid groups, such as

Hydroxyalkyl esters of alpha, beta-olefinically unsaturated carboxylic acids, such as hydroxyalkyl esters of acrylic acid, methacrylic acid and ethacrylic acid, in which the hydroxyalkyl group contains up to 20 carbon atoms, such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3-

Hydroxybutyl, 4-hydroxybutyl acrylate, methacrylate or ethacrylate; 1,4-bis (hydroxymethyl) cyclohexane, octahydro-4,7-methano-1 H-indene-dimethanol or

Methyl propanediol monoacrylate, monomethacrylate, monoethacrylate or monocrotonate; or

Reaction products from cyclic esters, such as' e.g. epsilon-caprolactone and these hydroxyalkyl esters;

olefinically unsaturated alcohols such as allyl alcohol;

Allyl ethers of polyols such as trimethylolpropane monoallyl ether or pentaerythritol mono-, di- or triallyl ether. The higher functional monomers (a1) are generally used only in minor amounts. In the context of the present invention are subordinate Amounts of higher-functional monomers are to be understood as amounts which do not lead to crosslinking or gelling of the block copolymers, unless they should be in the form of crosslinked microgel particles; 5

Reaction products from alpha.beta-olefinisch

Carboxylic acids with glycidyl esters of an alpha-branched monocarboxylic acid with 5 to 18 carbon atoms in the molecule. Implementation of the

10 acrylic or methacrylic acid with the glycidyl ester one

Carboxylic acid with a tertiary alpha carbon atom can take place before, during or after the polymerization reaction. The reaction product of acrylic and / or methacrylic acid is preferred as monomer (2)

15 used the glycidyl ester of Versatic® acid. This

Glycidyl ester is commercially available under the name Cardura® E10. In addition, reference is made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, pages 605 and 606;

20

Formaldehyde adducts of aminoalkyl esters of alpha.beta- olefinically unsaturated carboxylic acids and of alpha.beta- unsaturated carboxamides, such as N-methiol and N, N-dimethylol-aminoethyl acrylate, aminoethyl ethacrylate,

25 acrylamide and methacrylamide; such as

Olefinically unsaturated monomers containing acryloxysilane groups and hydroxyl groups, can be prepared by

Reaction of hydroxy-functional silanes with epichlorohydrin

30 and subsequent implementation of the intermediate with an alpha.beta-olefinically unsaturated carboxylic acid, especially acrylic acid and methacrylic acid, or their hydroxyalkyl esters;

(3) vinyl esters of monocarboxylic acids with 5 to 18 carbon atoms in the molecule which are branched in the alpha position, such as the vinyl esters of Versatic® acid which are sold under the brand VeoVa®;

(4) cyclic and / or acyclic olefins, such as ethylene, propylene, but-1-ene, pent-1-ene, hex-1-ene, cyclohexene, cyclopentene, norbones,

Butadiene, isoprene, cyclopentadiene and / or dicyclopentadiene;

(5) amides of alpha.beta-olefinically unsaturated carboxylic acids, such as (meth) acrylic acid amide, N-methyl, NN-dimethyl, N-ethyl, N, N-diethyl, N-propyl, N, N-dipropyl, N-butyl, N, N-dibutyl and / or

N, N-Cyclohexyl-methyl- (meth) acrylamide;

(6) monomers containing epoxy groups, such as the glycidyl ester of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid and / or itaconic acid;

(7) vinyl aromatic hydrocarbons, such as styrene, vinyl toluene or alpha-alkylstyrenes, especially alpha-methylstyrene;

(8) nitriles such as acrylonitrile or methacrylonitrile;

(9) vinyl compounds selected from the group consisting of

Vinyl halides such as vinyl chloride, vinyl fluoride, vinylidene dichloride,

vinylidene; Vinyl amides such as N-vinyl pyrrolidone; Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n- Butyl vinyl ether, isobutyl vinyl ether and vinyl cyclohexyl ether; as well as vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate;

(10) allyl compounds selected from the group consisting of allyl ether and esters such as propyl allyl ether, butyl allyl ether,

Ethylene glycol diallyl ether trimethylol propane triallyl ether or

Allyl acetate or allyl propionate; what the more functional

As far as monomers are concerned, the above applies analogously;

(11) polysiloxane macromonomers, which are number average

Molecular weight Mn from 1,000 to 40,000 and on average 0.5 to 2.5 ethylenically unsaturated double bonds per molecule, such as polysiloxane macromonomers, which have a number average molecular weight Mn from 1,000 to 40,000 and on average 0.5 to 2.5 ethylenically unsaturated double bonds per molecule exhibit; in particular polysiloxane macromonomers which have a number average molecular weight Mn of 2,000 to 20,000, particularly preferably 2,500 to 10,000 and in particular 3,000 to 7,000 and on average 0.5 to 2.5, preferably 0.5 to 1.5, ethylenically unsaturated double bonds per molecule, as in the DE

38 07 571 A1 on pages 5 to 7, DE 37 06 095 A1 in columns 3 to 7, EP 0 358 153 B1 on pages 3 to 6, in US 4,754,014 A1 in columns 5 to 9, in DE 44 21 823 A1 or in international patent application WO 92/22615 on page 12, line 18, to page 18, line 10; and

(12) Monomers containing carbamate or allophanate groups, such as

Acryloyloxy or methacryloyloxyethyK propyl or butyl carbamate or allophanate; further examples of suitable monomers which contain carbamate groups are described in US Pat 3,479,328 A 1, US 3,674,838 A 1, US 4,126,747 A 1, US 4,279,833 A 1 or US 4,340,497 A 1.

Compounds of the general formula I are used as monomers (b).

In the general formula I, the radicals R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen atoms or substituted or unsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl arylalkyl or arylcycloalkyl radicals, with the proviso that at least two of the variables R ¹ , R ² , R ³ and R ⁴ stand for substituted or unsubstituted aryl, arylalkyl or arylcycloalkyl radicals, in particular substituted or unsubstituted aryl radicals.

Examples of suitable alkyl radicals are methyl, ethyl, propyl, isopropyl, n-butyl, iso-butyl, tert-butyl, amyl, hexyl or 2-ethylhexyl.

Examples of suitable cycloalkyl radicals are cyclobutyl, cyclopentyl or cyclohexyl.

Examples of suitable alkylcycloalkyl radicals are methylenecyclohexane, ethylenecyclohexane or propane-1,3-diylcyclohexane.

Examples of suitable cycloalkylalkyl radicals are 2-, 3- or 4-methyl, ethyl, propyl or butylcyclohex-1-yl.

Examples of suitable aryl radicals are phenyl, naphthyl or biphenylyl.

Examples of suitable alkylaryl radicals are benzyl or ethylene or propane-1,3-diyl-benzene. Examples of suitable cycloalkylaryl radicals are 2-, 3-, or 4-phenylcyclohex-1-yl.

Examples of suitable arylalkyl radicals are 2-, 3- or 4-methyl, ethyl, propyl or butylphen-1-yl.

Examples of suitable arylcycloalkyl radicals are 2-, 3- or 4-cyclohexylphen-1 -yl.

The radicals R ¹ , R ² , R ³ and R ⁴ described above can be substituted. For this purpose, electron-withdrawing or electron-donating atoms or organic residues can be used.

Examples of suitable substitutes are halogen atoms, in particular chlorine and fluorine, nitrile groups, nitro groups, partially or completely halogenated, in particular chlorinated and / or fluorinated, alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl and Arylcycloalkyl radicals, including those exemplified above, in particular tert-butyl; Aryloxy, alkyloxy and cycloalkyloxy radicals, in particular phenoxy, naphthoxy, methoxy, ethoxy, propoxy, butyloxy or cyclohexyloxy; Arylthio, alkylthio and cycloalkylthio radicals, in particular phenylthio, naphthylthio, methylthio, ethylthio, propylthio, butylthio or cyclohexylthio; hydroxyl groups; and / or primary, secondary and / or tertiary amino groups, in particular amino, N-methylamino, N-ethylamino, N-propylamino, N-phenylamino, N-cyclohexylamino, N, N-dimethylamino, N, N-diethylamino, NN-dipropylamino , NN-diphenylamino, N, N-dicyclohexylamino, N-cyclohexyl-N-methylamino or N-ethyl-N-methylamino. Examples of monomers (b) used with particular preference in accordance with the invention are diphenylethylene, dinaphthaleneethylene, eis or trans-stilbene, vinylidene-bis (4-N, N-dimethylaminobenzene), vinylidene-bis (4-aminobenzene) or vinylidene-bis (4- nitrobenzene).

According to the invention, the monomers (b) can be used individually or as a mixture of at least two monomers (b).

With regard to the conduct of the reaction and the properties of the resulting block copolymers, diphenylethylene is of very particular advantage and is therefore used with very particular preference according to the invention.

Each of the above-mentioned monomers (a) can be polymerized alone with the monomer (b). According to the invention, however, it is advantageous to use at least two monomers (a) because this allows the profile of properties of the resulting block copolymers to vary very widely in a particularly advantageous manner and can be adapted very specifically to the particular intended use of the aqueous dispersions (A).

The monomers (a) are preferably selected such that the property profile of the block copolymers is essentially determined by the (meth) acrylate monomers described above, the monomers (a), which come from other monomer classes, advantageously and widely varying this property profile.

In this way, dispersing functional groups (i) or (ii) and / or (iii) or are preferably incorporated into the block copolymers, by means of which the block copolymers become hydrophilic, so that they can be dispersed or dissolved in aqueous media. Installation is preferably carried out in the first stage of the production of the block copolymer

In addition, isocyanate-reactive functional groups are incorporated which can crosslink with the polyisocyanates described below.

The block copolymers are prepared by reacting at least one monomer (b) with at least one monomer (a), in particular at least one hydrophilic monomer (a), in a first stage (1) to give a copolymer or a macroinitiator. After its isolation or directly in the reaction mixture, preferably directly in the reaction mixture, this copolymer or this macroinitiator is then reacted in at least one further stage (2) with at least one further, preferably hydrophobic, monomer (a) under radical conditions. The reaction is preferably carried out in the absence of an initiator of the radical polymerization.

Steps (1) and (2) can also be carried out in succession in one reactor. For this purpose, the monomer (b) is first reacted completely or partially with at least one monomer (a) depending on the desired application and the desired properties, after which at least one further monomer (a) is added and polymerized by free radicals. In a further embodiment, at least two monomers (a) are used from the start, the monomer (b) first reacting with one of the at least two monomers (a) and then the resulting copolymer above a certain molecular weight also with the further monomer (a) responding. The weight ratio of the copolymer or macroinitiator formed in the first stage (1) to the further monomer (s) (a) in the further stage (s) (2) is preferably 1:25 to 5: 1, preferably 1:22 to 4: 1, particularly preferably 1:18 to 3: 1, very particularly preferably 1:16 to 2: 1 and in particular 1:15 to 1: 1.

Depending on how the reaction is carried out, it is possible to produce bock copolymers with block, multiblock, gradient (co) polymer, star and branch structures, which may also be functionalized at the end groups.

Examples of initiators of free-radical polymerization which can be used are: dialkyl peroxides, such as di-tert-butyl peroxide or dicumyl peroxide; Hydroperoxides, such as cumene hydroperoxide or tert-butyl hydroperoxide; Peresters such as tert-butyl perbenzoate, tert-butyl perpivalate, tert-butyl per-3,5,5-trimethyl hexanoate or tert-butyl per-2-ethyl hexanoate; Potassium, sodium or ammonium peroxodisulfate; Azodinitriles such as azobisisobutyronitrile; C-C-cleaving initiators such as benzpinacol silyl ether; or a combination of a non-oxidizing initiator with hydrogen peroxide. Further examples of suitable initiators are described in German patent application DE 196 28 142 A1, page 3, line 49, to page 4, line 6.

Comparatively large amounts of free-radical initiator are preferably added, the proportion of the initiator in the reaction mixture, based in each case on the total amount of the monomers (a) and (b) and of the initiator, particularly preferably 0.5 to 50% by weight, being very particular is preferably 1 to 20% by weight and in particular 2 to 15% by weight. The weight ratio of initiator to monomers (b) is preferably 4: 1 to 1: 4, particularly preferably 3: 1 to 1: 3 and in particular 2: 1 to 1: 2. Further advantages result if the initiator within the specified limits Excess is used.

The two-stage or multi-stage radical copolymerization or block copolymerization is carried out in an aqueous or an organic medium.

If the block copolymerization is carried out in an organic medium, the resulting organic solution or dispersion of the block copolymer or the block copolymers is dispersed in an aqueous medium, resulting in a secondary dispersion (A). The organic solvents contained therein are optionally distilled off.

If the block mixed polymerization is carried out in an aqueous medium, the result is aqueous primary dispersions (A) which, as such, can be used directly for the preparation of the coating materials to be used according to the invention.

The block copolymerization is preferably carried out in an aqueous medium.

The aqueous medium essentially contains water. The aqueous medium can contain minor amounts of the additives described below and / or other dissolved solid, liquid or gaseous, low and / or high molecular weight substances, especially bases, provided that these do not negatively influence or even inhibit the copolymerization and / or more volatile for emission organic compounds. In the context of the present invention, the term “minor amount” is understood to mean an amount which does not cancel out the aqueous character of the aqueous medium. However, the aqueous medium can also be pure water.

Examples of suitable bases are low molecular weight bases such as sodium hydroxide solution, potassium hydroxide solution, ammonia, diethanolamine, triethanolamine, mono-, di- and triethylamine, and / or dimethylethanolamine, in particular ammonia and / or di- and / or triethanolamine.

Reactors for the (co) polymerization processes are the customary and known stirred tanks, stirred tank cascades, tubular reactors, loop reactors or Taylor reactors, as described, for example, in the patents DE 198 28 742 A1 or EP 0 498 583 A1 or in the article by K. Kataoka in Chemical Engineering Science, Volume 50, No. 9, 1995, pages 1409 to 1416. The radical copolymerization is preferably carried out in stirred tanks or Taylor reactors, the Taylor reactors being designed so that the conditions of the Taylor flow are met over the entire length of the reactor, even if the kinematic viscosity of the reaction medium changes greatly due to the copolymerization, in particular increases (cf. German patent application DE 198 28 742 A 1).

The copolymerization is advantageously carried out at temperatures above room temperature and below the lowest decomposition temperature of the monomers used in each case, preferably a temperature range from 10 to 150 ° C. 50 to 120 ° C and in particular 55 to 110 ° C is very particularly preferably selected.

If particularly volatile monomers (a) and / or (b) are used, the copolymerization can also be carried out under pressure, preferably under 1.5 to 3000 bar, preferably 5 to 1500 and in particular 10 to 1000 bar.

With regard to the molecular weight distributions, the block copolymer is not subject to any restrictions.

However, the copolymerization is advantageously carried out so that a

Molecular weight distribution Mw / Mn measured with

Gel permeation chromatography using polystyrene as

Standard of <4, preferably particularly preferably <2 and in particular <1.5 and in individual cases also <1.3 results. The

Molecular weights of the block copolymers are determined by the choice of

Ratio of monomer (a) to monomer (b) to radical initiator controllable within wide limits. In particular, the content of monomer (b) determines the molecular weight, in such a way that the greater the proportion of monomer (b), the lower the amount obtained

Molecular weight.

The proportion of block copolymers in the aqueous dispersions (A) can vary widely. It is preferably 10 to 70, preferably 15 to 65, particularly preferably 20 to 60, very particularly preferably 25 to 55 and in particular 30 to 50% by weight, in each case based on the aqueous dispersion (A).

The content of the aqueous dispersions (A) of the coating material to be used according to the invention can in any case vary widely depends on the requirements of the individual case. The content is preferably 10 to 80, preferably 15 to 75, particularly preferably 20 to 70, very particularly preferably 25 to 65 and in particular 30 to 60% by weight, based on the coating material.

The coating material to be used according to the invention further contains at least one crosslinking agent component which contains or consists of at least one polyisocyanate. The crosslinking agent component can contain inert organic solvents in order to lower the viscosity of the polyisocyanates so that they can be more easily mixed with the other constituents of the coating material to be used according to the invention

The statistical average of the polyisocyanates contains at least 2.0, preferably more than 2.0 and in particular more than 3.0 isocyanate groups per molecule. There is basically no upper limit to the number of isocyanate groups; According to the invention, however, it is advantageous if the number does not exceed 15, preferably 12, particularly preferably 10, very particularly preferably 8.0 and in particular 6.0.

Examples of suitable polyisocyanates are polyurethane prepolymers containing isocyanate groups, which can be prepared by reacting polyols with an excess of diisocyanates and are preferably low-viscosity.

Examples of suitable diisocyanates are isophorone diisocyanate (= 5-isocyanato-1-isocyanatomethyl-1, 3,3-trimethyl-cyclohexane), 5-isocyanato-1 - (2-isocyanatoeth-1-yl) -1, 3,3-trimethyl- cyclohexane, 5-isocyanato-1 - (3-isocyanatoprop-1-y!) - 1, 3,3-trimethyl-cyclohexane, 5-isocyanato- (4-isocyanatobut-1-yl) -1, 3,3-trimethyI -cyclohexane, 1-isocyanato-2- (3- isocyanatoprop-1-yl) -cyclohexane, 1-isocyanato-2- (3-isocyanatoeth-1-yl) cyclohexane, 1-isocyanato-2- (4-isocyanatobut-1-yl) -cyclohexane, 1,2-diisocyanatocyclobutane, 1,3-diisocyanatocyclobutane, 1, 2-

Diisocyanatocyclopentane, 1, 3-diisocyanatocyclopentane, 1,2-diisocyanatocyclohexane, 1, 3-diisocyanatocyclohexane, 1, 4-

Diisocyanatocyclohexane, dicyclohexylmethane-2,4'-diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI),

Ethylethylene diisocyanate, trimethylhexane diisocyanate, heptamethylene diisocyanate or diisocyanates, derived from dimer fatty acids, as sold by the Henkel company under the trade name DDI 1410 and described in the patents WO 97/49745 and WO 97/49747, in particular 2-heptyl-3,4-bis (9-isocyanatononyl) -1-pentyl-cyclohexane, or 1, 2-, 1, 4- or 1, 3- bis (isocyanatomethyl) cyclohexane, 1, 2-, 1, 4- or 1, 3-bis (2nd -isocyanatoeth-1-yl) cyclohexane, 1, 3-bis (3-isocyanatoprop-1-yl) cyclohexane, 1,2-, 1, 4- or 1, 3-bis (4-isocyanatobut ~ 1-yl) cyclohexane or liquid bis (4-isocyanatocyclohexyl) methane having a trans / trans content of up to 30% by weight, preferably 25% by weight and in particular 20% by weight, as described in patent applications DE 44 14 032 A1, GB 1220717 A1, DE 16 18 795 A1 or DE 17 93 785 A1 is described, preferably isophorone di-isocyanate, 5-isocyanato-1 - (2-isocyanatoeth-1-yl) -1,3,3-trimethyl- cyclohexane, 5-isocyanato-1- (3-isocyanatoprop-1-yl) -1,3,3-tr imethyl-cyclohexane, 5-isocyanato- (4-isocyanatobut-1-yl) -1,3,3-trimethyl-cyclohexane, 1-isocyanato-2- (3-isocyanatoprop-1-yl) -cyclohexane, 1-isocyanato- 2- (3-isocyanatoeth-1-yl) cyclohexane, 1-isocyanato-2- (4-isocyanatobut-1-yl) cyclohexane or HDI, especially HDI.

It can also have isocyanurate, biuret, allophanate, iminooxadiazinedione, urethane, urea, carbodiimide and / or uretdione groups Polyisocyanates are used which are prepared in a customary and known manner from the diisocyanates described above. Examples of suitable production processes and polyisocyanates are, for example, from the patents CA 2,163,591 A, US-A-4,419,513, US 4,454,317 A, EP 0 646 608 A, US 4,801, 675 A, EP 0 183 976 A 1, DE 40 15 155 A 1, EP 0 303 150 A 1, EP 0 496 208 A 1, EP 0 524 500 A 1, EP 0 566 037 A 1, US 5,258,482 A 1, US 5,290,902 A 1, EP 0 649 806 A 1, DE 42 29 183 A 1 or EP 0 531 820 A1.

The content of the coating materials to be used according to the invention in the polyisocyanates described above can vary very widely. The content depends in particular on the functionality of the polyisocyanates on the one hand and the number of isocyanate-reactive functional groups in the binders on the other hand and on the crosslinking density which the coatings should have. The content is preferably 1 to 30, preferably 2 to 28, particularly preferably 3 to 24, very particularly preferably 3 to 22 and in particular 3 to 20% by weight, in each case based on the coating material.

The coating material to be used according to the invention may also contain at least one, in particular one, primary aqueous dispersion (C) of at least one (meth) acrylate copolymer which is different from the aqueous dispersion (A). Primary aqueous dispersions (C) are common and known products and are sold, for example, by Zeneca under the Neocryl® brand, for example Neocryl® XK 90. The primary aqueous dispersions (C) are preferably used to grind the pigments described below. In addition, the coating material to be used according to the invention can also give color and / or effect, fluorescent, electrically conductive and / or magnetically shielding pigments, metal powder, organic and inorganic, transparent or opaque fillers and / or nanoparticles (collectively “pigments (D)”) contain.

Examples of suitable effect pigments are platelet pigments such as commercially available aluminum bronzes, aluminum bronzes chromated according to DE 36 36 183 A1, and commercially available stainless steel bronzes as well as non-metallic effect pigments, such as pearlescent or interference pigments, platelet-shaped effect pigments based on iron oxide and brown, a shade of pink has or liquid crystalline effect pigments. In addition, Römpp Lexikon Lacquers and Printing Inks, Georg Thieme Verlag, 1998, pages 176, "Effect Pigments" and pages 380 and 381 "Metal Oxide Mica Pigments" to "Metal Pigments", and the patent applications and patents DE 36 36 156 A1, DE 37 18 446 A1, DE 37 19 804 A1, DE 39 30 601 A1, EP 0 068 311 A1, EP 0 264 843 A1, EP 0 265 820 A1, EP 0 283 852 A1, EP 0 293 746 A 1, EP 0 417 567 A 1, US 4,828,826 A or US 5,244,649 A.

Examples of suitable inorganic color pigments are white pigments such as titanium dioxide, zinc white, zinc sulfide or lithopone; Black pigments such as carbon black, iron-manganese black or spinel black; Colored pigments such as chromium oxide, chromium oxide hydrate green, cobalt green or ultramarine green, cobalt blue, ultramarine blue or manganese blue, uitramarin violet or cobalt and manganese violet, iron oxide red, cadmium sulfoselenide, molybdate red or ultramarine red; Iron oxide brown, mixed brown, spinel and corundum phases or chrome orange; or Iron oxide yellow, nickel titanium yellow, chrome titanium yellow, cadmium sulfide, cadmium zinc sulfide, chrome yellow or bismuth vanadate.

Examples of suitable organic color pigments are monoazo pigments, bisazo pigments, anthraquinone pigments,

Benzimidazole Pigments, Quinacridone Pigments, Quinophthalone Pigments, Diketopyrroiopyrrole Pigments, Diσxazine Pigments, Inάanthron Pigments, Isoindoline Pigments, Isoindolinone Pigments, Azomethine Pigments,

Thioindigo pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments or aniline black.

In addition, Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pages 180 and 181, "Iron Blue Pigments" to "Iron Oxide Black", Pages 451 to 453 "Pigments" to "Pigment Volume Concentration", page 563 "Thioindigo Pigments", Pages 567 "Titanium dioxide pigments", Pages 400 and 467, "Naturally occurring pigments", Page 459 "Polycyclic pigments", Page 52, "Azomethine pigments", "Azo pigments", and Page 379, "Metal complex pigments" ,

Examples of fluorescent pigments (daylight pigments) are bis (azomethine) pigments.

Examples of suitable electrically conductive pigments are titanium dioxide / tin oxide pigments.

Examples of magnetically shielding pigments are pigments based on iron oxides or chromium dioxide. Examples of suitable metal powders are powders made from metals and metal alloys aluminum, zinc, copper, bronze or brass.

Examples of suitable organic and inorganic fillers are chalk, calcium sulfates, barium sulfate, silicates such as talc, mica or kaolin, silicas, oxides such as aluminum hydroxide or magnesium hydroxide or organic fillers such as plastic powders, in particular made of polylamide or polyacrylonitrile. In addition, reference is made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pages 250 ff., "Füllstoffe".

Examples of suitable transparent fillers are those based on silicon dioxide, aluminum oxide or zirconium oxide.

Suitable nanoparticles are selected from the group consisting of hydrophilic and hydrophobic, in particular hydrophilic, nanoparticles based on silicon dioxide, aluminum oxide, zinc oxide, zirconium oxide and the polyacids and heteropolyacids of transition metals, preferably of molybdenum and tungsten, with a primary article size <50 nm, preferably 5 to 50 nm, in particular 10 to 30 nm. The hydrophilic nanoparticles preferably have no matting effect. Nanoparticles based on silicon dioxide are particularly preferably used.

Hydrophilic pyrogenic silicon dioxides are very particularly preferably used, the agglomerates and aggregates of which have a chain-like structure and which can be produced by flame hydrolysis of silicon tetrachloride in a detonating gas flame. These are sold, for example, by Degussa under the brand Aerosil ®. Precipitated water glasses, such as nanohectorites, are also particularly preferred for example, sold by Südchemie under the Optigel ® brand or by Laporte under the Laponite ® brand.

In addition to the pigments (D) described above, the coating material to be used according to the invention may also contain at least one further additive.

Examples of suitable further additives are other crosslinking agents, such as blocked, other than the polyisocyanates (B)

Polyisocyanates, aminoplast resins, or tris (alkoxycarbonylamino) triazines, molecularly dispersible dyes, light stabilizers, such as UV absorbers and reversible radical scavengers (HALS), antioxidants, low and high-boiling ("long") organic solvents, deaerating agents, wetting agents, emulsifiers, slip additives, polymerization inhibitors,

Crosslinking catalysts, thermolabile free radical initiators, thermally curable reactive thinners, adhesion promoters, leveling agents, film-forming aids, rheology aids (thickeners),

Flame retardants, corrosion inhibitors, pouring aids, waxes, siccatives, biocides and / or matting agents, such as those in the

Textbook "Lackadditive" by Johan Bieleman, Wiley-VCH, Weinheim,

New York, 1998.

From a methodological point of view, the production of the coating materials to be used according to the invention has no peculiarities, but instead takes place by mixing the components described above in conventional and known mixing units, such as stirred kettles, Ultraturrax, inline dissolvers, extruders or kneaders. In terms of method, the coating materials to be used according to the invention are also not peculiar, but can be carried out by all customary application methods, such as, for example, spraying, knife coating, brushing, pouring, dipping, trickling or rolling. Spray application methods are preferably used, such as, for example, compressed air spraying, airless spraying, high rotation, electrostatic spray application (ESTA), if appropriate combined with hot spray application, such as hot air hot spraying.

The curing of the applied coating materials also has no special features in terms of method, but instead takes place according to the customary and known thermal methods, such as heating in a forced-air oven or irradiation with IR lamps.

The new coated medium-density fibreboards have scratch-resistant, glossy coatings, which have a uniform flow and a smooth surface without faults, such as craters or pinholes, are free of light-dark shades (clouds) and against all household chemicals, including active chlorine are resistant. The new coated medium-density fibreboards are therefore ideally suited for the production of interior doors, wooden cassettes, cheap furniture and furniture back panels.

Production Example 1

The manufacture of a markro initiator

In a steel reactor, as is usually used for the production of

Dispersions was used, equipped with a stirrer, a reflux condenser and 3 feed vessels, 1,591, 1 part by weight VE- Submitted water and heated to 70 ° C. 308.2 parts by weight of acrylic acid, 555.2 parts by weight of methyl methacrylate and 45.2 parts by weight of diphenylethylene were placed in the first feed vessel. 300.1 parts by weight of 25 percent ammonia solution were placed in the second feed vessel. 159 parts by weight of demineralized water and 68.2 parts by weight of ammonium peroxodisulfate were placed in the third feed vessel. The three feeds were started simultaneously with vigorous stirring of the initial charge in the steel reactor. The first and second feed were metered in within four hours. The third feed was metered in over 4.5 hours. The resulting reaction mixture was kept at 70 ° C. for four hours and then cooled to below 40 ° C. and filtered through a 100 μm GAF bag. The resulting dispersion had a solids content of 33 to 34% by weight (1 hour, 130 ° C.) and a free monomer content of less than 0.2% by weight (determined by gas chromatography).

Preparation example 2

The preparation of the dispersion (A) of a block copolymer

In a steel reactor, as is usually used for the production of dispersions, equipped with a stirrer, a reflux condenser and an inlet vessel, 1,361.7 parts by weight of demineralized water and 240 parts by weight of the dispersion according to Preparation Example 1 were placed and heated to 80 ° C. with stirring , A mixture of 260 parts by weight of n-butyl methacrylate, 208 parts by weight of styrene, 334 parts by weight of hydroxyethyl methacrylate and 234.4 parts by weight of ethylhexyl methacrylate was then metered in from the feed vessel over the course of six hours. The resulting reaction mixture was stirred at 80 ° C for two hours. The resulting dispersion was then cooled below 40 ° C. and filtered through a 50 μm GAF bag. The dispersion (A) had a solids content of 42 to 43% by weight (1 hour, 130 ° C.) and a free monomer content of less than 0.2% by weight (determined by gas chromatography).

example 1

The production of coated medium density fiberboard

For the production of the coated medium-density fibreboard, a base coat was first made

150 parts by weight of dispersion (A) from preparation example 2,

100 parts by weight of a commercially available aqueous primary dispersion of a methacrylate copolymer (Neocryl® XK 90 from Zeneca), containing titanium dioxide white pigment (Glasurit® FensterColor 30 / B 035 from BASF Coatings AG),

1.5 parts by weight of a commercially available defoaming agent (Agitan ® E 256 from Münzing Chemie),

6.0 parts by weight of a commercially available polydimethylsiloxane

Dispersion (Wacker Sl finish CT12E from Wacker Chemie) and

5 parts by weight of deionized water manufactured.

Shortly before application, the base coating was mixed with 13.25 parts by weight of a polyisocyanate (trimeric hexamethylene diisocyanate of the isocyanurate type, Basonat® P LR 8878 from BASF Aktiengesellschaft, 56 percent in 1-methoxypropylacetate-2 / acetone).

The coating material was applied with the aid of cup guns to medium-density fibreboards which were provided with a primer, prepared from a solution of a commercially available methacrylate copolymer (Uracron® CY476E from DSM) in methyl ethyl ketone. The wet layer thickness was adjusted such that after the layers had hardened for 60 minutes at 40 ° C., dry layer thicknesses of 50 to 70 μm resulted.

The coatings had a uniform flow and a smooth surface. The gloss was 14 to 18 ° with a measuring angle of 60 °. The scratch resistance and chemical resistance to chlorine-containing cleaning agents were excellent.

Claims

Coated medium-density fibreboards, process for their production and their use

1. Medium-density fiberboard which is coated on at least one of its surfaces, the coating being producible by applying at least one coating material to at least one surface and curing the resulting layer or layers, characterized in that at least one of the coating materials

(A) the aqueous dispersion of at least one block copolymer, which on average has at least two isocyanate-reactive functional groups and is obtainable by the two-stage or multi-stage, controlled free-radical batch polymerization in an aqueous or an organic medium, where

(1) in a first stage

(a) at least one olefinically unsaturated monomer and

(b) at least one of the olefinically unsaturated

Monomer (a) various olefinically unsaturated monomer of the general formula I

R ¹ R ² C = CR ³ R ⁴ (I), in which the radicals R ¹ , R ² , R ³ and R ⁴ each independently of one another represent hydrogen atoms or substituted or unsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl,

Aryl, alkylaryl, cycloalkylaryl, arylalkyl or arylcycloalkyl radicals, with the proviso that at least two of the variables R ¹ , R ² , R ³ and R ^{4 are} substituted or unsubstituted aryl, arylalkyl or arylcycloalkyl radicals, in particular substituted or unsubstituted Aryl residues, stand;

copolymerized, after which

(2) in a second stage, at least one further monomer (a) is polymerized in the presence of the copolymer formed in the first stage without the addition of free radical initiators (co);

and

(B) at least one crosslinking agent component with at least one polyisocyanate

contains.

2. Medium density fiberboard according to claim 1, characterized in that the coating material (C) at least one primary aqueous dispersion of at least one (meth) acrylate copolymer different from the aqueous dispersions (A)

contains.

3. Medium density fiberboard according to claim 1 or 2, characterized in that the coating material

(D) at least one pigment

contains.

4. Medium density fiberboard according to claim 3, characterized in that the pigments from the group consisting of coloring and / or effect, fluorescent, electrically conductive and magnetically shielding pigments, metal powders, organic and inorganic, transparent and opaque fillers and nanoparticles, selected become.

5. Medium-density fiberboard according to one of claims 1 to 4, characterized in that the block copolymer (A) can be prepared by at least one monomer (b) with at least one hydrophilic monomer (a) to a copolymer in the first stage (1) implements.

6. Medium-density fiberboard according to one of claims 1 to 5, characterized in that the block copolymer (A) can be produced by at least one further stage (2) reacting the resulting copolymer with at least one hydrophobic monomer (a).

7. Medium density fiberboard according to one of claims 1 to 6, characterized in that the aryl radicals R ¹ , R ² , R ³ and / or R ^{4 of} the monomers (b) are phenyl or naphthyl radicals.

8. Medium density fiberboard according to claim 7, characterized in that it is phenyl radicals.

9. Medium density fiberboard according to one of claims 1 to 8, characterized in that the substituents in the radicals R ¹ , R ² , R ³ and / or R ^{4 of} the monomers (b) from the group consisting of electron-withdrawing or electron-donating atoms or organic residues.

10. Medium density fiberboard according to claim 9, characterized in that the substituents from the group consisting of halogen atoms, nitήl, nitro, partially or fully halogenated alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, Cycloalkylaryl, arylalkyl and arylcycloalkyl radicals; Aryloxy, alkyloxy and cycloalkyloxy radicals; Arylthio, alkylthio and cycloalkylthio residues and primary, secondary and / or tertiary amino groups can be selected.

11. Medium density fiberboard according to one of claims 5 to 10, characterized in that the hydrophilic monomer (a) contains at least one functional group consisting of the group consisting of (i) functional groups which can be converted into anions by neutralizing agents and anionic groups,

or

(ii) functional groups which can be converted into cations by neutralizing agents and / or quaternizing agents and cationic groups,

and

(iii) nonionic hydrophilic groups,

is selected.

12. Medium density fiberboard according to claim 11, characterized in that the functional groups (i) from the group consisting of carboxylic acid, sulfonic acid and

Phosphonic acid groups, acidic sulfuric acid and

Phosphoric acid ester groups and carboxylate, sulfonate, phosphonate, sulfate ester and phosphate ester groups, the functional groups (ii) from the group consisting of primary, secondary and tertiary amino groups, primary, secondary, tertiary and quaternary ammonium groups, quaternary phosphonium groups and tertiary sulfonium groups, and the functional groups (iii) are selected from the group consisting of omega-hydroxy and omega-alkoxy-poly (alkylene oxide) -1-yl groups.

13. Medium density fiberboard according to claim 11 or 12, characterized in that the neutralizing agent for the functional groups convertible into anions (i) from the group consisting of ammonia, trimethylamine, triethylamine,

Tributylamine, dimethylaniline, diethylaniline, triphenylamine, dimethylethanolamine, diethylethanolamine, methyldiethanolamine, 2-aminomethylpropanol, dimethylisopropylamine,

Dimethylisopropanolamine, triethanolamine, diethylene triamine and triethylene tetramine, and the neutralizing agents for the functional groups convertible into cations (ii) are selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, lactic acid, dimethylol propionic acid and citric acid.

14. Medium density fiberboard according to one of claims 5 to 13, characterized in that the hydrophobic monomers (a) from the group consisting of

(1) essentially acid group-free esters of olefinically unsaturated acids;

(2) monomers which carry at least one hydroxyl group or hydroxymethylamino group per molecule and are essentially free of acid groups;

(3) vinyl esters of alpha-branched monocarboxylic acids having 5 to 18 carbon atoms in the molecule; (4) cyclic and / or acyclic olefins;

(5) amides of olefinically unsaturated carboxylic acids;

(6) monomers containing epoxy groups;

(7) vinyl aromatic hydrocarbons;

(8) nitriles;

(9) vinyl compounds selected from the group consisting of vinyl halides, N-vinyl amides, vinyl ethers and vinyl esters;

(10) allyl compounds selected from the group consisting of allyl ethers and esters;

(11) Polysiloxane macromonomers which have a number average molecular weight Mn of 1,000 to 40,000 and an average of 0.5 to 2.5 ethylenically unsaturated double bonds per

Have molecule; and

(12) monomers containing carbamate or allophanate groups;

to be selected.

15. Medium-density fiberboard according to one of claims 1 to 14, characterized in that the isocyanate-reactive functional groups are selected from the group consisting of hydroxyl groups, primary and secondary amino groups, thiol groups and imino groups.

16. Medium density fiberboard according to claim 15, characterized in that one uses hydroxyl groups.

17. Use of the medium density fiberboard according to one of claims 1 to 16 for the production of doors, wooden cassettes, furniture and furniture back panels.