WO2001098414A1 - Wood-duroplastic composites - Google Patents

Abstract

The invention relates to wood-duroplastic composites with high dimensional stability and weather resistance, consisting of partially acetylated and optionally phosphorylated wood and melamine resins or urea resins. Said composites are produced according to the following method: after a sorption process and reaction with alkenyl acetates of the formula R-C(=CH2)-O-CO-CH3, semi-finished wood products or wood products are subjected to sorption and reacted with an ammonia alkaline aqueous solution of pre-polymers of melamine resins and/or urea resins, which contain latent curing agents and optionally phosphorylating agents. The wood-duroplastic composites are suitable for use as high-performance semi-finished wood products and wood products with low water-absorption, high dimensional stability and weather resistance, in particular for use as parquet elements, floorboards and for external applications in the construction industry.

Description

 Wood thermoset composites

The invention relates to wood-thermoset composites of high dimensional stability, durability and flame resistance from semi-finished wood products or wood products and thermosets produced therefrom by machining.

The use of urea-melamine-formaldehyde resins in particle board manufacture (EP 0 913 411) and of melamine resins as flame retardants for wood (US Pat. No. 4,839,0S9) is known.

It is also known to improve the fungus resistance of woods by impregnation with dispersions of polyacrylates or alkyd resins [Militz, H., Material and Organisms 28 (1993/1994) 1, 55-73].

It is also known to wood by reaction with acetic anhydride, or benzylation and subsequent reaction with resorcinol (Shiraishi, N., in: Wood and Cellulosic Chemistry, Marcel Dekker New York 1991, pp. 861-881) or by treatment with ammonia [Bariska, M., ACS Symp. Ser. 43 (1977), 326-347].

A disadvantage of the known solutions for wood modification according to the prior art is that only a part of the problems can be solved with all modification methods. For example, it is possible to increase the dimensional stability and durability by acetylation with acetic anhydride, while the flame resistance and the resistance to mechanical stress remain unchanged or are reduced.

The object of the present invention was to develop wood-thermoset composites with high dimensional stability, durability, flame resistance and strength against mechanical stress with the lowest possible thermoset content and a technologically simple process for their production.

The object according to the invention was achieved by wood-thermoset composites of high dimensional stability, durability and flame resistance from semi-finished wood products or wood products and thermosets produced therefrom by machining, the wood-thermoset composites according to the invention a) 65 to 99 mass% of partially acetylated and optionally phosphorylated wood, and b) 1 to 35 mass% of melamine resins and / or urea resins and have been produced by a process in which

Semi-finished wood products or wood products made therefrom by machining with a residual water content of 5 to 20% by mass, heating to a temperature of 75 to 160 ° C, optionally with sorption of 5 to 40% by mass, based on the semi-finished wood products or wood products, alkenyl acetates of the formula RC (= CH ₂ ) -O-CO-CH ₃ , where R = H or R = CC ₄ -alkyl, were subsequently subjected to the semi-finished wood products or wood products with an ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins Molar mass number averages of 200 to 5000 were soaked, the solution having a solids content of prepolymers of melamine resins and / or urea resins of 10 to 60 mass%, an ammonia content of 1 to 20 mass%, a latent hardener content of 0.05 up to 2.0% by mass and, if appropriate, a content of salts of phosphoric acid, phosphorous acid and / or polyphosphoric acid as phosphorylating agents of 1 to 30 mas se%, and were subsequently cured at 140 to 200 ° C with removal of a mixture containing water and ammonia.

The semi-finished wood products are preferably boards, profiles or beams made of softwood or hardwood. Examples of wood products are parts of balcony and terrace cladding and garden furniture.

The melamine resins in the wood-thermoset composites are preferably melamine-formaldehyde resins and / or melamine-phenol-formaldehyde resins. Preferred urea resins are urea-formaldehyde resins and / or melamine-urea-formaldehyde resins.

The melamine-formaldehyde resins, melamine-phenol-formaldehyde resins and / or melamine-urea-formaldehyde resins can also, as a melamine component, 0.1 to 80% by mass of melamine derivatives and / or triazine derivatives such as 2- (2-hydroxyethylamino) -4,6-diamino-1, 3,5-triazine, 2- (5-hydroxy-3-oxapentylamino) -4,6-diamino-1, 3,5-triazine, 2,4,6 - tris - (6-aminohexylamino) -1,3,5-triazine, 2,4- (di-5-hydroxy-3-oxapentylamine) -6-methyl-1,3,5-triazine. Ammeline and / or hydrophobized melamine-formaldehyde alcoholates from CrC ₃ alcohols.

In addition to urea-formaldehyde resins, the urea resins can also consist of mixed condensates with phenols, acid amides or sulfonic acid amides. In the case of the melamine resins or urea resins contained in the wood-duroplastic compounds, 0.5 to 100 mol% of the methylol groups can optionally be reacted with d- to C ₄ -aliphatic alcohols such as methanol, ethanol or isobutanol, polyalkylene oxides such as polyethylene oxide or polypropylene oxide etherified with molecular weights from 500 to 2500 and / or C ₃ -C ₂ - (meth) acrylic acid hydroxyalkyl esters such as hydroxybutyl acrylate or hydroxyethyl methacrylate, by reaction with unsaturated acid amides of the acrylamide or methacrylamide type and / or mono- or diester of phosphoric acid or phosphorous Acid modified.

In the wood-thermoset composites, melamine resins and / or urea resins are also preferred which contain 5 to 50% by mass, based on the melamine resins and / or urea resins, of coupled blocks of polyacrylates, unsaturated polyesters, modified maleic anhydride copolymers and / or polyether urethanes. The blocks can be coupled to polyacrylates, unsaturated polyesters, modified maleic anhydride copolymers and / or polyether urethanes to the melamine resins and / or urea resins by polymer-analogous reaction of the functional groups contained in the polyacrylates, unsaturated polyesters, modified maleic anhydride copolymers and / or polyether urethanes with the functional groups the thermoset prepolymers, by free-radical polymerization of the monomers on which the polyacrylates are based in the presence of the thermoset prepolymers or by preparing the thermoset prepolymers in the presence of the polyacrylates, unsaturated polyesters, modified maleic anhydride copolymers and / or polyether urethanes.

Examples of suitable polyacrylates which are incorporated as blocks in the thermoset prepolymer component of the wood-thermoset composites are polyacrylates from monomer mixtures of acrylamide / methyl methacrylate / ethyl acrylate / 2-hydroxyethyl methacrylate, styrene / methyl methacrylate / hydroxyethyl methacrylate / 2-ethylhexyl acrylate or methacrylamide / Butyl acrylate / butyl methacrylate / ethylhexyl methacrylate, hydroxyethyl methacrylate / methyl methacrylate / styrene.

Examples of suitable modified maleic anhydride copolymers which are incorporated as blocks in the thermoset prepolymer component of the wood-thermoset composites are maleic anhydride-styrenic copolymers. the alkylene oxides with poly-C C _4, preferably poly CC ₄ -alkylenoxideπ having amino end groups, or long-chain alkylamines are modified. Examples of suitable unsaturated polyesters which are incorporated as blocks in the thermoset prepolymer component of the wood-thermoset composites are polyesters based on adipic acid, maleic anhydride, diethylene glycol and neopentyl glycol or polyesters based on phthalic anhydride, maleic anhydride, diethylene glycol and ethylene glycol.

Examples of suitable polyether urethanes are polyurethanes with polytetrahydrofuran blocks as the polyether component.

The wood-thermoset composites of high dimensional stability, durability and flame resistance from semi-finished wood products or wood products and thermosets produced therefrom by machining are produced according to the invention by two process variants which differ in the technology of sorption of the alkenyl acetates in the first process stage. In the liquid phase sorption process, the alkenyl acetates are sorbed by the semi-finished wood or wood products made from it by machining in the first process stage from the liquid phase, in the gas phase sorption process by the gas phase.

In the liquid phase sorption process, wood-thermoset composites, which consist of a) 65 to 99% by mass of partially acetylated and optionally phosphorylated wood, and b) 1 to 35% by mass of melamine resins and / or urea resins, are produced by a multi-stage process, in which in the first stage of the process, semi-finished wood or wood products made from it by machining with a residual water content of 5 to 20% by mass in an autoclave for 20 to 200 min to a vacuum of -0.005 to -0.1 MPa and at the same time to a temperature of 40 to 2 degrees below the boiling temperature of the alkenyl acetates used, but at most to a temperature of 150 ° C., and subsequently based on this temperature, a pressure of 5 to 100 MPa and a residence time of 40 to 400 min, a sorption of 10 to 50% by mass on the semi-finished wood products or wood products, alkenyl acetates of the formula RC (= CH ₂ ) -O-CO-CH ₃ , where R = H or R = C ₁ -C ₄ -alkyl , are subjected, and after separation of the unsorbed portions of alkenyl acetates under inert gas at a pressure of 5 to 100 MPa and a residence time of 20 to 300 min to a temperature of 2 to 40 degrees. but at most, be above the boiling point of the alkenyl acetates used to a temperature of 160 C ^Q heated, and optionally thereafter evacuiert 10 min to 100 min in a vacuum -0.005 to -0.1 MPa, - In the second process stage, the semi-finished wood products or wood products modified in the first process stage at the final temperature reached in the first process stage under an inert gas atmosphere, a pressure of 1 to 5 MPa and a residence time of 30 to 420 min with an ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins are impregnated with number average molecular weights of 200 to 5000, the solution having a solids content of prepolymers of melamine resins and / or urea resins of 10 to 60 mass%, an ammonia content of 1 to 20 mass%, a content of latent hardeners from 0.05 to 2.0% by mass and, if appropriate, a content of salts of phosphoric acid, phosphorous acid and / or polyphosphoric acid as phosphorylation agents from 1 to 30% by mass, and after removal of the non-sorbed portions of ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins, latent hardeners and where appropriate, phosphorylating agents are subsequently cured at 140 to 200 ° C. under a vacuum of - 0.005 to -0.1 MPa and a residence time of 15 to 150 min, with the removal of a mixture containing water and ammonia.

In the gas phase sorption process, wood-thermoset composites, which consist of a) 65 to 99% by mass of partially acetylated and optionally phosphorylated wood, and b) 1 to 35% by mass of melamine resins and / or urea resins, are produced using a multi-stage process in which

- In the first stage of the process, semi-finished wood products or wood products made therefrom by machining with a residual water content of 5 to 20% by mass in an autoclave were evacuated for 20 to 200 min to a vacuum of -0.005 to -0.1 MPa and at the same time to a temperature of 75 ° C to 160 ° C, and then at this temperature, a residence time of 40 to 400 min, and optionally a vacuum of -0.1 to - 0.99 MPa, from gas phase sorption and reaction with 10 to 50 % By mass, based on the semi-finished wood or wood products, alkenylacetates of the formula RC (= CH ₂ ) -O-CO-CH ₃ , where R = H or R = C 1 -C ₄ -alkyl, are subjected, and if appropriate subsequently 10 min can be evacuated to a vacuum of - 0.005 to -0.1 MPa up to 100 min, •

- In the second process stage, the semi-finished wood products or wood products modified in the first process stage at the final temperature reached in the first process stage under an inert gas atmosphere, a pressure of 1 to 5 MPa and a residence time of 30 to 420 min with an ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins with number average molecular weights of 200 to 5000 are soaked, the solution having a solids content of prepolymers of melamine resins and / or urea resins of 10 to 60 mass%, an ammonia content of 1 to 20 mass%, a latent hardness content of 0.05 to 2.0 % By mass and optionally a content of salts of phosphoric acid, phosphorous acid and / or polyphosphoric acid as phosphorylating agents of 1 to 30% by mass, and after removal of the non-sorbed portions of ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins, latent hard materials and optionally Phosphorylating agents are subsequently cured at 140 to 200.degree. C. under a vacuum of -0.005 to -0.1 MPa and a residence time of 15 to 150 min with removal of a mixture containing water and ammonia.

Examples of the alkenyl acetates of the formula RC (= CH ₂ ) -O-CO-CH ₃ used in the first process stage in the liquid-phase sorption process or gas-phase absorption process are vinyl acetate and isopropenyl acetate, isopropenyl acetate being preferred. Alkenylacetates as acetylation agents for wood are characterized by an improved reactivity compared to acetic anhydride.

In the case of the liquid phase sorption process or gas phase sorption process, in the first stage of the process the required soφtion time for the alkenylacetates used is determined by the sorption temperature, the type of wood used, the residual water content of the wood and the cross section of the wood products. The higher the residual water content and wood cross-section, the longer sorption times are required. Wood products made from spruce and larch require significantly longer absorption times than wood products made from poplar, pine or beech.

Examples of the inert gases used in the second process stage are nitrogen or argon.

The solids content of the ammoniacal aqueous solutions of prepolymers of melamine resins and / or urea resins used in the second process stage is 10 to 60% by mass, preferably 25 to 35% by mass.

The prepolymers of melamine resins used in the second process stage preferably have a melamine / formaldehyde ratio of 1: 1.5 to 1: 4, particularly preferably 1: 2.2 to 1: 2.8. The preferred molar ratio of urea to formaldehyde for the production of urine-formaldehyde prepolymers is 1: 1.4 to 1: 1.6.

The ammoniacal aqueous solutions of prepolymers used are preferably metered from a storage container, which is preceded by a thermoset prepolymer synthesis station.

The latent hardeners added are preferably salts which split off acid components at elevated temperature, esters which hydrolyze at elevated temperature with the liberation of acid components, and / or thiourea. Suitable salts are ammonium salts, especially ammonium peroxidisulfate, ammonium phosphate, ammonium sulfate, ammonium chloride, ammonium oxalate and / or ammonium rhodanide; -C-C ₄ alkyl ammonium salts of carboxylic acids, especially methyl ammonium phthalate, methyl ammonium maleate and / or the methylamine salt of naphthalenesulfonic acid. Suitable esters are esters of phosphoric acid, phosphorous acid, oxalic acid and / or phthalic acid, in particular diethyl phosphate, dimethyl oxalate and / or dimethyl phthalate.

Suitable phosphorylating agents, which are optionally used in the second process stage of the liquid phase soapy process or gas phase soothing process, are salts of phosphoric acid, phosphorous acid and / or polyphosphoric acid. Examples of phosphorylating agents are ammonium phosphate, ammonium polyphosphate and sodium phosphite.

In all process variants, it is advantageous to recover the ammonia from the mixture of vacuum degassing containing ammonia and water.

The wood-thermoset composites according to the invention are preferably suitable for highly stressed semi-finished wood products and wood products with low water absorption, high dimensional stability and weathering resistance, in particular for parquet elements, planking boards and outdoor applications in the building industry such as window parts.

The invention is illustrated by the following examples: example 1

In a 4.62 m ³ stainless steel autoclave (0 = 1, 70, l = 2.3 m) preheated to 82 ° C with a temperature jacket for heating and cooling, fine weighing equipment, fittings for liquid dosing with 5 m ³ buffer vessel, gassing and degassing , a transport trolley is set, which is filled with 500 kg of birch wood profiled planks (2.00 x 0.1 x 0.02 m, residual water content 8.2% by mass), separated by spacers.

After closing the autoclave, a vacuum of - 0.01 MPa is applied and the autoclave is left at this temperature for 55 min. After decompression and nitrogen flushing, the autoclave is filled with isopropenyl acetate at 82 ° C. via the buffer vessel and a pressure of 15 MPa is set. After 180 min, the pressure is let down and the non-sorbed portions of isopropenyl acetate are drawn off via the bottom valve. The increase in mass of the birch plywood boards is 85 kg.

After exposure to a nitrogen pressure of 10 MPa, the mixture is heated to 120 ° C. and the autoclave is left at this temperature for 45 minutes.

The autoclave is then depressurized and filled at 120 ° C. via the buffer vessel with an ammoniacal aqueous solution of a melamine-phenol-formaldehyde prepolymer (M _n = 450), which has a solids content of 30% by mass and an ammonia content of 8% by mass. owns and contains 1.5 mass% ammonium peroxydisulfate as latent hardener, and treated the partially acetylated birch wood profile boards at 120 ° C. and a pressure of 1.5 MPa with the aqueous resin solution. The melamine-phenol-formaldehyde prepolymer had been produced in the thermoset prepolymer synthesis station by condensation of melamine / phenol / formaldehyde (30%) in a molar ratio of 0.8: 0.2: 3.2 at 80 ° C./2.5 hours. After a sorption time of 150 min, the pressure is released and the non-sorbed resin solution is drawn off via the bottom valve. The mixture is then cured at 185 ° C. under a vacuum of -0.01 MPa and a residence time of 110 min, with the separation of a mixture containing water and ammonia.

The resulting composite of birch wood and melamine-phenol-formaldehyde-Har∑ has a thermoset content of 16% by mass, a water absorption after 24 hours of water aging at 25 ° C of 48% by mass and a thickness increase after 24 hours of water storage 25 ° C of 4.5%. As a comparison, non-modified birch wood profiles have a water absorption of 73% by mass after 24 hours of water storage at 25 ° C and a thickness increase of 7.5% after 24 hours of water storage at 25 ° C.

To test the resistance to fungi, 20 test specimens 50 x 20 x 20 mm were produced from the birch wood composite, washed out according to EN 84, dried to constant weight at 105 ° C and inoculated with the Coriolus versicolor mushroom strain. After 4 months storage at 22 ° C and 65% rel. Moisture was dried to constant weight at 105 ° C. The average mass loss was 3.5%, compared to 24% for untreated birch wood.

Example 2

In a 4.62 m ³ stainless steel autoclave preheated to 78 ° C (0 = 1.70 m, l = 2.3 m) with temperature control jacket for heating and cooling, fine weighing device, fittings for liquid dosing with 5 m ³ buffer vessel, gassing and Degassing, a transport trolley is set, which is filled with 300 kg of pinewood board (2.00 x 0.12 x 0.02 m, residual water content 11.2% by mass), separated by spacers.

After closing the autoclave, a vacuum of - 0.02 MPa is applied and the autoclave is left at this temperature for 70 min. After relaxation and nitrogen purging, the autoclave is filled with vinyl acetate at 78 ° C via the buffer vessel and a pressure of 20 MPa is set. After 160 minutes, the pressure is released and the non-sorbed portions of vinyl acetate are drawn off via the bottom valve. The increase in mass of the pine wood boards is 39 kg.

After exposure to a nitrogen pressure of 8 bar, the mixture is heated to 110 ° C. and the autoclave is left at this temperature for 60 min. The autoclave is then depressurized and at 110 ° C over the buffer vessel with an ammoniacal aqueous solution (solids content 35% by mass, content of ammonium oxalate as latent hardener 0.75% by mass, content of ammonia 11% by mass) of a modified meiamin-urea-formaldehyde Prepolymer (M _n = 1750) containing 35% by mass of a chemically bound butyl acrylate-hydroxyethyl acrylate-styrene copolymer (64: 32: 4).

The modified melamine-urea-formaldehyde prepolymer (M _n = 1750), the 35 mass% of a chemically bound butyl acrylate-hydroxyethyl acrylate-styrene copolymer (64: 32: 4) was in the thermoset prepolymer synthesis station by condensation ^' of melamine / urea / formaldehyde (30%) in a molar ratio 0.7: 0.3: 3.2 at 85 ° C / 2.0 hours and subsequently, within 3.5 hours at 80 ° C., addition of a monomer mixture of butyl acrylate, hydroxyethyl acrylate styrene (64: 32: 4), which contains 0.9% by mass of azoisibutyronitrile.

After a sorption time of 150 min at 105 ° C, the pressure is released and the non-sorbed resin solution is drawn off via the bottom valve. The mixture is then cured at 195 ° C. under a vacuum of - 0.01 MPa and a residence time of 90 min, with the separation of a mixture containing water and ammonia.

The resulting combination of pine wood and modified melamine-urea-formaldehyde resin, which contains 35 mass% of a chemically bound butyl acrylate-hydroxyethyl acrylate-styrene copolymer (64: 32: 4), has a thermoset content of 12.9 mass %, a water absorption after 24 hours of water storage at 25 ° C of 44% by mass and a thickness increase after 24 hours of water storage at 25 ° C of 4.2%.

As a comparison, unmodified pine wood profiles have a water absorption of 70% by mass after 24 hours of water storage at 25 ° C and a thickness increase of 7.3% after 24 hours of water storage at 25 ° C.

To test the resistance to fungi, 20 test specimens 50 x 20 x 20 mm were produced from the pinewood composite, washed out according to EN 84, dried to constant weight at 105 ° C and inoculated with the Coriolus versicolor mushroom strain. After 4 months storage at 22 ° C and 65% rel. Moisture was dried to constant weight at 105 ° C. The average loss of mass was 2.5%, compared to 18% for untreated pine.

Example 3

In a 4.62 m ³ stainless steel autoclave preheated to 140 ° C (0 = 1.70 m, l = 2.3 m) with temperature jacket for heating and cooling, fine weighing device, dosing device for gases with evaporation device for liquids, fittings for liquid dosing, Fumigation and degassing, a transport trolley is set, which is filled with 420 kg poplar wood profiled boards (2.00 x 0.1 x 0.02 m, residual water content 7.4% by mass), separated by spacers. After closing the autoclave, a vacuum of - 0.01 MPa is applied and the autoclave is left at this temperature for 55 min. After depressurization and nitrogen flushing, the autoclave is gassed with isopropenyl acetate at 140 ° C. with a residence time of 140 min. The increase in mass of the poplar wood boards is 29 kg.

The autoclave is then depressurized and filled at 140 ° C over the buffer vessel with an ammoniacal aqueous solution of a melamine resin prepolymer with coupled blocks of a modified styrene-maleic anhydride copolymer, which have a solids content of 42% by mass, an ammonia content of 10% by mass Has content of ammonium sulfate as a latent hardener of 1.5% by mass and a content of ammonium polysulfate as a phosphorylating agent of 30% by mass, and treated the partially acetylated poplar wood profile boards at 140 ° C. and a pressure of 1.5 MPa with the aqueous resin solution.

The melamine resin prepolymer with coupled blocks of a modified styrene-maleic anhydride copolymer had been prepared as follows: 40 kg of 30% aqueous formalin solution and 12.6 kg of melamine are introduced into a 200 liter stirred reactor with an azeotropic separator and reflux condenser, with NaOH to pH = 7.1 set and condensed at 80 ° C within 40 min. 50 kg of a 50% aqueous solution of a dodecylamine-modified maleic anhydride-styrene copolymer (molar mass M _n = 2500, molar ratio styrene / maleic anhydride 1: 1) are then introduced into the stirred reactor and stirred at 85 ° C. for 1 hour.

After a sorption time of 170 min, the autoclave is depressurized and the unsorbed resin solution is drawn off via the bottom valve. The mixture is then cured at 180 ° C. under a vacuum of - 0.01 MPa and a residence time of 140 min, with the separation of a mixture containing water and ammonia.

The resulting composite of poplar wood and melamine resin with coupled blocks of a modified styrene-maleic anhydride copolymer has a thermoset content of 34% by mass, a water absorption after 24 hours of water storage at 25 ° C of 32% by mass and a thickness increase after 24 hours of water storage at 25 ° C of 4.1%. As a comparison, unmodified poplar wood profiles have a water absorption after 24 hours of water storage at 25 ° C of 74% by mass and a thickness increase after 24 hours of water storage at 25 ° C of 8.5%.

To test the resistance to fungi, 20 test specimens 50 x 20 x 20 mm were produced from the poplar wood composite, washed out according to EN 84, dried to constant weight at 105 ° C and inoculated with the Coriolus versicolor mushroom strain. After 4 months storage at 22 ° C and 65% rel. Moisture was dried to constant weight at 105 ° C. The average mass loss was 3.3%, compared to 28% for untreated poplar wood.

Claims

claims Claim 1 Wood-thermoset composites of high dimensional stability, durability and flame resistance from semi-finished wood products or wood products and thermosets made therefrom by machining, characterized in that the wood-thermoset composites from a) 65 to 99 mass% partially acetylated and optionally phosphorylated wood, and b ) 1 to 35% by mass of melamine resins and / or urea resins and have been produced by a process in which - Semi-finished wood products or wood products made therefrom by machining with a residual water content of 5 to 20% by mass, heating to a temperature of 75 to 160 ° C with sorption of 5 to 40% by mass, based on the semi-finished wood products or wood products, alkenyl acetates of the formula RC ( = CH ₂ ) -O-CO-CH ₃ , where R = H or R = CC -alkyl, have been subjected, subsequently the semi-finished wood or wood products with an ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins with number average molecular weights of 200 to 5000 were soaked, the solution having a solids content of prepolymers of melamine resins and / or urea resins of 10 to 60% by mass, an ammonia content of 1 to 20% by mass and optionally a content of salts of phosphoric acid, phosphorous acid and / or Has polyphosphoric acid as phosphorylating agents from 1 to 30% by mass, and subsequently contain water and ammonia the mixture was cured at 140 to 200 ° C. Claim 2 Wood-thermoset composites according to claim 1, characterized in that the semi-finished wood boards, profiles or beams made of softwood or hardwood. Claim 3 Wood-thermoset composites according to claim 1 or 2, characterized in that the melamine resins are melamine-formaldehyde resins and / or melamine-phenol-formaldehyde resins and the urea resins are urea-formaldehyde resins and / or melamine-urea-formaldehyde resins, in which optionally etherified from 0.5 to 100 mol% of the methylol groups by reaction with C to C ₄ aliphatic alcohols, polyalkylene oxides with molar masses from 500 to 2500 and / or C ₅ -C ₂ - (meth) acrylic acid hydroxyalkyl esters and / or by reaction with unsaturated acid amides of the acrylamide or methacrylamide type and / or mono- or diesters of phosphoric acid or phosphorous acid have been modified. Claim 4 Wood-thermoset composites according to one or more of claims 1 to 3, characterized in that the melamine resins and / or urea resins 5 to 50% by mass, based on the melamine resins and / or urea resins, coupled blocks of polyacrylates, unsaturated polyesters, modified maleic anhydride copolymers and / or contain polyurethane. Claim 5 Process for the production of wood-thermoset composites of high dimensional stability, durability and flame resistance from semi-finished wood products or wood products and thermosets made therefrom by machining, characterized in that the wood-thermoset composites from a) 65 to 99 mass% partially acetylated and / or phosphorylated wood, and b) 1 to 35% by mass of melamine resins and / or urea resins are produced by a multi-stage process in which - In the first stage of the process, semi-finished wood products or wood products made therefrom by machining with a residual water content of 5 to 20% by mass in an autoclave are evacuated for 20 to 200 minutes to a vacuum of -0.005 to -0.1 MPa and at the same time to a temperature of 40 to 2 Grd below the boiling point of the alkenylacetates used, but at most to a temperature of 150 ° C, and then at this temperature, a pressure of 5 to 100 MPa and a residence time of 40 to 400 min, a sorption of 5 to 40 mass% , based on the semi-finished wood products or wood products, are subjected to alkenyl acetates of the formula RC (= CH ₂ ) -O-CO-CH ₃ , where R = H or R = CC ₄ -alkyl, and after removal of the unsorbed portions of alkenylacetates under inert gas at a pressure of 5 to 100 MPa and a residence time of 20 to 300 min to a temperature of 2 to 40 degrees above the boiling point of the alkenylacetates used, but at most to a temperature of 160.degree , are heated, and if necessary subsequently evacuated for 10 min to 100 min to a vacuum of -0.005 to 0.1 MPa, in the second process stage the semi-finished wood products or wood products modified in the first process stage at the final temperature reached in the first process stage under an inert gas atmosphere, a pressure of 1 to 5 MPa and a residence time of 30 to 420 min with an ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins with a number average molecular weight of 200 to 5000, the solution having a solids content of prepolymers of melamine resins and / or urea resins from 10 to 60% by mass, a Geha lt has 1 to 20% by weight of ammonia, a latent hardener content of 0.05 to 2.0% by weight and, if appropriate, a content of salts of phosphoric acid, phosphorous acid and / or polyphosphoric acid as phosphorylating agents of 1 to 30% by weight, and after separation of the non-sorbed portions of ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins, latent hard materials and optionally phosphorylating agents, subsequently under a vacuum of -0.005 to -0.1 MPa and a residence time of 15 to 150 min with the separation of water and Ammonia-containing mixture can be cured at 140 to 200 ° C. Claim 6 Process for the production of wood-thermoset composites of high dimensional stability, durability and flame resistance from semi-finished wood products or wood products and thermosets made therefrom by machining, characterized in that the wood-thermoset composites from a) 65 to 99 mass% partially acetylated and / or phosphorylated wood, and b) 1 to 35% by mass of melamine resins and / or urea resins are produced by a multi-stage process in which - In the first stage of the process, semi-finished wood products or wood products made therefrom by machining with a residual water content of 5 to 20% by mass an autoclave is evacuated for 20 to 200 min to a vacuum of -0.005 to -0.1 MPa and at the same time heated to a temperature of 75 ° C to 160 ° C, and subsequently at this temperature, a residence time of 40 to 400 min, and optionally a vacuum of -0.1 to - 0.99 MPa, from the gas phase of a soφtion and reaction with 5 to 40% by mass, based on the semi-finished wood or wood products, alkenyl acetates of the formula RC (= CH ₂ ) -O-CO-CH ₃ , where R = H or R = CC ₄ alkyl, are subjected, and if necessary subsequently evacuated for 10 min to 100 min to a vacuum of -0.005 to -0.1 MPa, in the second process stage that in the first process stage modified semi-finished wood products or wood products at the final temperature reached in the first process stage under an inert gas atmosphere, a pressure of 1 to 5 MPa and a residence time of 30 to 420 min with an ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins Number average molecular weights of 200 to 5000 are soaked, the solution having a solids content of prepolymers of melamine resins and / or urea resins of 10 to 60% by mass, an ammonia content of 1 to 20% by mass. has a content of latent hardness of 0.05 to 2.0% by mass and, if appropriate, a content of salts of phosphoric acid, phosphorous acid and / or polyphosphoric acid as phosphorylating agents of 1 to 30% by mass, and after removal of the unsorbed portions of ammoniacal aqueous solution of prepolymers of melamine resins and / or urea resins, latent hardeners and optionally phosphorylating agents subsequently under a vacuum of -0.005 to -0.1 MPa and a residence time of 15 to 150 min with separation of a mixture containing water and ammonia at 140 to 200 ° C can be cured. Claim 7 Process for the production of wood - DuroplasL composites according to. Claim 5 or 6 _r characterized in that isopropenyl acetate is used as the alkenyl acetate of the formula RC (= CH ₂ ) -0-CO-CH ₃ . Claim 8 Process for the production of Holz_-DuroplasL composites according to one or more of claims 5 to 7, characterized in that the prepolymers of melamine resins have a ratio of melamine / formaldehyde vαn.1: .1.5 to. l: -4 _r . prefers! 2 _^ Z to 1: 2.8 _^ heseats -