EP1979139A1

EP1979139A1 - Method for the reduction of formaldehyde emissions in wood materials

Info

Publication number: EP1979139A1
Application number: EP07703814A
Authority: EP
Inventors: Eva RÜBA; Stephan WEINKÖTZ; Michael Schmidt; Michael Finkenauer; Christian Beil; Ralph Lunkwitz
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2006-01-17
Filing date: 2007-01-12
Publication date: 2008-10-15
Also published as: MY146656A; CA2631869A1; BRPI0706437A2; NZ569380A; AU2007206994B2; AU2007206994A1; JP2009523628A; US20100190021A1; CA2631869C; US8460761B2; WO2007082837A1; JP5328370B2; NO20082648L

Abstract

The invention relates to a method for reducing the emission of formaldehyde in wood materials by applying nitrogen-containing compounds. Said method is characterized in that (i) a mixture containing at least one polyamine and optionally up to 20 percent by weight of urea relative to the mixture is applied to the wood material; (ii) polyamine is applied onto or into the chip cake or fiber cake; (iii) polyamine is applied to the coating substrate used for finishing the surface; and/or (iv) polyamine is applied to the exposed points. The polyamines have a minimum molecular weight of 500 g/mol while being provided with at least 6 primary or secondary amino groups.

Description

Method for reducing the formaldehyde emission in wood-based materials

description

The present invention relates to a process for formaldehyde emission reduction in wood-based materials by treatment with polyamines. Furthermore, the present invention relates to a wood material, which can be produced by the present method, as well as laminates produced by the present process and the use of these wood materials and laminates for the production of furniture, packaging materials or interior fittings.

Wood-based panels are a cost-effective and resource-saving alternative to solid wood and have gained great importance especially in furniture construction and as building materials. The starting materials are wood layers of different thicknesses, wood strips, wood shavings or wood fibers from different woods. Such wood parts or wood particles are usually pressed with natural and / or synthetic binders and optionally with the addition of further additives to plate or strand-shaped wood materials.

Formaldehyde-containing adhesives are frequently used as binders, for example urea-formaldehyde resins or melamine-containing urea-formaldehyde resins. The resins are produced by polycondensation of formaldehyde with urea or melamine. In order to obtain good adhesive properties, an excess of formaldehyde is generally used. This can lead to free formaldehyde in the finished wood material. By hydrolysis of the polycondensates additional formaldehyde can be released. The free formaldehyde contained in the wood material and the formaldehyde released by hydrolysis during the lifetime of the wood material can be released to the environment.

Even wood itself can release formaldehyde to the environment, especially after a heat treatment. Coated wood-based materials generally have lower emissions of formaldehyde than uncoated substrates ("Wood as Raw Material", Volume 47, 1989, page 227).

Formaldehyde may cause allergies, skin, respiratory or eye irritation above certain limits in humans. The reduction of formaldehyde emission in interior components is therefore an important concern.

A lowering of the formaldehyde emission by reduced addition of formaldehyde in the production leads only to a limited extent to success, since the adhesive properties of the binder deteriorate with decreasing formaldehyde concentration, and the setting of the adhesive is markedly slowed down. This leads to prolonged production tion cycles (described in "wood materials and glues", M. Dunky, P. Niemz, Springer Verlag Berlin-Heidelberg, 2002, 251-302).

Another possibility for reducing the formaldehyde emission is the addition of formaldehyde scavengers such as urea to the wood particles or the formaldehyde resin. A disadvantage of this method, however, is the slower setting rate of the resin. In addition, the mechanical properties of the products are adversely affected.

The formaldehyde emission of wood-based panels has been reduced in recent years through various measures. Examples for this are:

G. Myers (Forest Products Journal 1986, VoI 36 (6), 41-51) gives an overview of possible methods. These range from the application of low molecular weight formaldehyde scavengers such as urea or ammonia in solid form (for example as ammonium bicarbonate), in aqueous solution (for example urea solution) or in gaseous form (NH3) until the application of a coating which acts as a physical barrier.

Technical importance have the fumigation of wood-based materials, in particular chipboard with ammonia (RY AB method, Verko method) and the spraying of the particle board with formaldehyde scavengers (Swedspan method) obtained (E. Roffael and H. Miertzsch, adhesion 1990, 4, 13 -19). In the Swedspan process (EP-B 0006486), the chipboard is sprayed while hot with aqueous solutions of urea or other solutions containing ammonia. A disadvantage is the poorer coatability of the chipboard treated in this way. When fumigating the wood-based materials with ammonia (RY AB process, Verko process), it has proven to be disadvantageous that the formaldehyde release increases again as the storage period increases (page 16, E. Roffael and H. Miertzsch, Adhäsion 1999, 4, 13- 19).

WO 2004/085125 A2 describes a method for reducing the emissions of bonded wood materials, in which mixtures of aldehyde- and isocyanate-reactive substances are applied to the straightened edges lying perpendicular to the direction of adhesive bonding. It should be retained both from the wood as well as from the adhesive escaping pollutants. For this purpose, substances which have an amino or amide group or hydroxyl-containing substances can be used. For example, urea, guanamine, ethylamine, ethanolamine, proteins, alcohols and carbohydrates are mentioned.

JP 2002-273145 A describes a method for reducing the formaldehyde emissions of wood composites, in which a plurality of measures, each individually suitable for reducing the formaldehyde emission, are combined. The described aqueous formaldehyde scavenger is composed of 20 to 50 wt .-% urea, and a Residual of a non-volatile amine, a means to increase the permeability of the wood so that the urea and the non-volatile amine can penetrate into the composite, and a film-forming solid which, upon drying, becomes a physical barrier to the formaldehyde on the wood composite. This film can affect the coatability of wood composites. As non-volatile amines and polyalkylenepolyamines are described. This class of substances is generally understood to mean short-chain, linear polyamines of the formula H 2 N (-CH 2 -CH 2 -NH) _n -H where n = 2, 3 and 4.

Despite many measures, such as the adaptation of the stoichiometry of the formaldehyde-containing binder or of the addition of formaldehyde scavengers, as well as different processes for the aftertreatment of wood-based materials, further measures are necessary to reduce the emission of formaldehyde from wood-based materials. Until now, the emission of formaldehyde from open areas, which is created after the final surface refinement and optionally after-treatment, for example by drilling, milling or sawing, has also been disregarded.

Such open areas can be found, for example, as holes in shelf walls or in furniture rear walls, which are required to ensure a flexibly adjustable height of the shelves. Furthermore, the edges of shelves that are not directed into the living area, usually not surface-coated and thus open. For some shelves, even the entire underside of the shelf is uncoated, which thus presents open surfaces from which formaldehyde escapes.

It is therefore an object of the invention to reduce the formaldehyde emission of wood materials, wherein neither the mechanical properties nor the coatability of the wood materials or the swelling values are to be adversely affected, as caused for example by excessive concentrations of urea in Formaldehydfängern or by application of ammonium salts can.

It is also the object of the invention to reduce the formaldehyde emission of surface-refined wood-based materials, without the adhesion or the quality, i. the appearance and the durability, the surface finishing is adversely affected. In addition, the process of coating should not be affected.

It is therefore also the object of the present invention to reduce the formaldehyde emission from open areas of a surface-refined wood material.

The solution of the problem is based on the known methods for reducing the formaldehyde emission in wood materials by applying nitrogen-containing compounds. The inventive method is then characterized in that (i) a mixture comprising at least one polyamine and optionally up to 20% by weight, based on the mixture, of urea is applied to the wood-based material;

(ii) polyamine is applied to or in the chip or fiber cake; (iii) is applied to the coating substrate polyamine used for the surface treatment and / or

(iv) polyamine is applied to the open areas; wherein the polyamines have a molecular weight of at least 500 g / mol and at least 6 primary or secondary amino groups

The term "chip or fiber cake" is understood to mean scattered, glued chips or fibers which have been precompressed if necessary, The chip or fiber cake generally has at least twice the thickness of the finished wood material.

The term "coating substrate" is understood as meaning, for example, aminoplast resin films, in particular melamine films, prepregs, films, laminates or veneers, and the like.

The term "open spots" in the present invention, holes, uncoated open edges or surfaces and the like understood, as they arise, for example, by subsequent drilling, milling or sawing after the surface finishing.

The polyamine can be applied in aqueous form or without the addition of solvents. Preferably, an aqueous polyamine solution is used.

The aqueous polymer solution is advantageously prepared by mixing - in each case based on the polymer solution -

(a) 1 to 99% by weight of polyamine

(b) 0 to 5% by weight of additives for improving wettability

(C) 0 to 30 wt .-% additives for adjusting the pH

(D) 0 to 30 wt .-% of other additives such as fungicides, water repellents, dyes, organic solvents

(e) 0 to 50% by weight of urea

and in addition to 100 wt .-% of water, these data refer to the beginning of mixing.

As component (a) a particular polyamine or mixtures of several polyamines can be used. The aqueous polyamine solution advantageously contains from 5 to 90% by weight of polyamine, preferably from 10 to 75% by weight of polyamine, in particular from 15 to 45% by weight of polyamine, particularly preferably from 25 to 40% by weight of polyamine, in each case based on the polymer solution ,

Preference is given to using polyamines which have a molecular weight of at least 500 g / mol, in particular at least 800 g / mol, and at least 6, in particular at least 10, primary or secondary amino groups. Preferred polyamines are hyperbranched polyamines, in particular polyethylenimine, or polyvinyl laminates or mixtures thereof.

The term "hyperbranched polyamines" in the present invention means highly functional, highly branched and hyperbranched polymers which contain amino or amido groups.

In the context of the invention, hyperbranched polyamines are any highly functional, highly branched and hyperbranched polyamines having a weight-average molecular weight of greater than 500 g / mol, whose main chain is branched, and which have a degree of branching (DB) of greater than or equal to zero , 05. Preference is given to using hyperbranched polyamines having a weight-average molecular weight of greater than 1,000 g / mol, preferably greater than 1,500 g / mol and in particular having a molecular weight of from 1,500 to 200,000 g / mol. The degree of branching is advantageously 0.1 and greater. The degree of branching of the hyperbranched polyamines is preferably between 0.2 to 0.99, particularly preferably between 0.3 and 0.95 and in particular between 0.35 and 0.75. To define the degree of branching, see H. Frey et al., Acta Polym. 1997, 48, 30.

Advantageously, the hyperbranched polyamines have at least four functional end groups, preferably at least eight functional end groups, in particular at least twenty functional end groups. The number of functional groups is in principle not limited above, but the hyperbranched polyamines of the present invention advantageously have fewer than 500 functional end groups, preferably less than 300 functional end groups, especially less than 150 functional end groups.

The method of preparation of the hyperbranched polyamines is described, for example, in WO 1996/19537, WO 1999/16810, WO 2005/075541, WO 2005/044897, WO 2003/0066702 and in the earlier German patent application with the file reference 102005056592.1 and the title "Production and Use of highly functional, hyperbranched or hyperbranched polylysines "described. Advantageously used as hyperbranched polyamines polycondensation and Polyadditi- onsprodukte, preferably polyureas, polyamides, polythioureas, as well as combination of mixed forms with two or more of these functional groups, such as polyamidoureas and polyamidothioureas, polyurea (thiourea) s, polyureaurethanes and polythiourea, polyester ureas and poly esteric thioureas, polyaminoureas and polyaminothioureas, polycarbonate ureas and polycarbonate thioureas, polyether ureas and polyether thioureas, polyamidourethanes, polyamidoesters, polyamidoamines, polyamidocarbonates, polyamidoethers, polyesterurethanes, polyaminourethanes, polycarbonate urethanes, polyetherurethanes, polyaminoesters, polyesteramides, polyaminocarbonates, polyaminoethers, or Polyurea urethanamides, etc. Polyureas, polythioureas, polyureas, polyamides, poly. Are particularly preferred as hyperbranched polymers esteramides used, in particular polyureas, polyureas, polyamides and in the polyamides particularly preferably polylysines.

Very particular preference is given to the use of polyethyleneimine or polyvinylamine or mixtures thereof.

The weight-average molecular weight of the polyvinylamine is advantageously 5,000 to 500,000 g / mol, preferably 5,000 to 350,000 g / mol, in particular 5,000 to 100,000 g / mol. The weight-average molecular weight of the polyethyleneimine is advantageously from 500 to 100,000 g / mol, preferably from 500 to 70,000 g / mol, more preferably from 500 to 50,000 g / mol, very preferably from 800 to 20,000 g / mol and in particular from 2,000 to 20,000 g / mol.

Polyethyleneimine can be prepared by acid catalyzed polymerization of ethyleneimine and is generally obtained as an aqueous solution at levels of from 20 to 100% by weight, preferably between 40 and 70% by weight, of polyethylenimine. Polyvinylamine can be prepared by polymerization of vinylformamide and subsequent hydrolysis and is generally obtained as an aqueous solution of from 2 to 50% by weight, preferably from 5 to 25% by weight. The degree of hydrolysis can be adjusted by the reaction conditions and determines the ratio of amine groups to formamide groups. Advantageously, these solutions can be used directly as a basis for the polyamine solutions according to the invention.

As optional component (b) of the aqueous polymer solution, in order to improve the wettability, ionic and nonionic surfactants, as described, for example, in H. Stäche, "Tensid-Taschenbuch", Carl Hanser Verlag, Munich, Vienna, 1981, can be advantageous in concentration 0 to 5 wt .-%, preferably from 0 to 2 wt%, are used. The pH can be adjusted by the following additives as optional component (c): mineral or organic acids such as sulfuric acid or formic acid. Component (c) may be added to the aqueous polymer solution from 0 to 30% by weight, preferably from 0 to 20% by weight.

As optional component (d) further additives may be added to the aqueous polymer solution, for example additives from the group of water repellents, e.g. As paraffin emulsions and waxes, fungicides, organic solvents or dyes. Component (d) may be added to the aqueous polymer solution from 0 to 30% by weight, preferably from 0 to 10% by weight.

As optional component (e), the aqueous polyamine solution may advantageously contain up to 20% by weight of urea, based on the polymer solution. The aqueous polymer solution particularly advantageously contains less than 15% by weight of urea, preferably less than 10% by weight of urea and in particular less than 5% by weight of urea, in each case based on the polymer solution. Most preferably, the polymer solution is free of urea.

The polyamine solution is advantageously applied at a pH of 3 to 12. In case (i), the polyamine solution is preferably applied with a pH of 7 to 11, more preferably with a pH of 9 to 1 1, wherein protonation of the polyamines can occur in the less preferred acidic range. In case (ii) and (iii), the polyamine solution is preferably applied at a pH of 5 to 10, especially at a pH of 6 to 8. In case (iv), the polyamine solution is preferably applied at a pH of 6 to 11, especially at a pH of 9 to 11.

A sufficient amount of polyamine solution is applied so that the amount of polyamine per square meter of surface area of the wood material is advantageously between 1 g and 200 g, preferably between 2 g and 50 g, more preferably between 3 g and 30 g (case (i) ).

In case (ii), a sufficient amount of polyamine solution is applied so that the amount of polyamine per 100 kilograms of chip or fiber cake advantageously between 0.01 kg and 5 kg, preferably between 0.05 kg and 1 kg, in particular between 0, 1 kg and 0.5 kg.

In case (iii), a sufficient amount of polyamine solution is applied so that the amount of polyamine per square meter of coating substrate is advantageously between 0.1 g and 100 g, preferably between 0.5 g and 30 g, in particular between 1 g and 15 g , In case (iv), a sufficient amount of polyamine solution is applied so that the amount of active substance polyamine per square meter surface area of the surface of the surface-treated wood material is advantageously between 0.05 g and 200 g, preferably between 0.1 g and 50 g preferably between 0.3 g and 30 g and in particular between 0.5 and 10 g.

The aqueous polymer solution can be applied to the wood-based material by various measures known to the person skilled in the art (case (i)). These include, for example, spraying, rolling, dipping, knife coating, brushing, curtain coating, preferably the polyamine solution is applied by spraying and rolling.

The application of the polyamine or the aqueous polyamine solution to the chips or fiber cake can be carried out by various measures known to the person skilled in the art (case (N)). These include, for example, spraying, rolling, knife coating, brushing, curtain coating, preferably the amine solution is applied by spraying.

For example, the aqueous polyamine solution can be applied to the top and / or bottom of the fiber cake. The application of the polyamine or the aqueous polymer solution may be carried out at an elevated temperature or at room temperature.

For example, the polyamine or aqueous polyamine solution may be applied before or after the cold compression / pre-compression. In a build-up of the chip or fiber cake of topcoat-middlecoat topcoat, the polyamine or polyamine solution may be in one or more layers and / or present between the individual layers. The polyamine is preferably applied to the cover layer (s), preferably to both cover layers, of the chip or fiber cake.

The application to the lower cover layer, for example, indirectly via the application to the conveyor belt, which conveys the fiber cake to the press, take place. In this case, the required amount of polyamine solution is applied to the conveyor belt, for example by spraying or rolling, and then the glued chips or fibers are scattered onto the conveyor belt.

For example, the polyamine or polyamine solution may be sprayed together with the vapor used to preheat the material of the press (see WO 2004/87388 and references herein).

The swarf or fiber cake treated with polyamine is pressed into a wood-based material by processes known to those skilled in the art (see "MDF - Medium-Density Fiberboard", Hans-Joachim Deppe, Kurt Ernst, 1996, DRW-Verlag Weinbrenner GmbH & Co., 70771 Leinfelden-Echterdingen, chapter 4.3, pages 81ff .; see also EP 1 192 223 B1, paragraph [0034] and "Taschenbuch der Spanplattentechnik" Joachim Deppe, Kurt Ernst, 2000, DRW-Verlag Weinbrenner GMbH & Co., 70771 Leinfelden-Echterdingen, chapter 3.5, pages 232ff).

In case (iii), the application of the aqueous polyamine solution or the polyamine to the coating substrate may be carried out by various means known to those skilled in the art. These include, for example, spraying, rolling, dipping, soaking, knife coating, brushing, curtain coating. Preferably, the amine solution is applied by spraying.

Preferably, the polyamine solution is applied to the backside of the coating substrate, i. on the wood material facing side, applied.

The coating substrate is then pressed with wood-based material by methods known to those skilled in the art.

For example, in the case of treating a veneer, the aqueous polyamine solution may be sprayed on the underside of the veneer. After applying the glue liquor on the wood-based board, z. B. chipboard, the thus treated veneer is placed and pressed under temperature and pressure.

For example, in the case of treating a melamine film, the aqueous polyamine solution (A) may be applied to the paper, e.g. Decorative paper or overlay paper,

(B1) can be added to the impregnating resin liquor for pre-impregnation, (B2) can be added to the impregnating resin liquor for post-impregnation / coating, (C) applied after impregnation of the paper or (D) applied only after drying of the impregnated paper.

Preferably, the aqueous polyamine solution is applied after drying the impregnated paper.

The preparation of the coating substrates resin film or laminate is generally carried out by the impregnation of papers, for example a) kraft papers with a basis weight between 50 to 150 g / m ² , b) printed decorative papers with a basis weight between 50 to 150 g / m ² or c ) Overlay papers with a basis weight of 20 to 50 g / m ² , by means of aqueous resin solutions, wherein the papers soaked with the resin solution and / or the resin solution is aufgerakelt or painted on the paper. Subsequently, the substrate is up to a residual moisture / water content dried from 2 to 8%. It is usually a basis weight in the case of a) from 100 to 250 g / m ² and in the case of b) and c) of 50 to 150 g / m ² .

These dried substrates are then used in case a), i. in the case of resin films, advantageously sprayed with polyamine, dried and pressed on HDF, MDF, chipboard or the like. The pressing pressure is usually between 5 and 80 bar, the pressing time is generally less than one minute, typically 10 to 30 seconds, the pressing temperature is about 160 to 200 ° C.

In case b), i. in the manufacture of laminates, multiple films are optionally sprayed, dried and then pressed together to form the laminate. A laminate usually consists of several layers of impregnated core paper, preferably 2 to 15 core papers, one or more impregnated decorative and / or overlay papers as the surface layer and optionally one or more impregnated webs of, for example, kraft paper. Optionally, all the films used, only individual films, only the core papers or only the interface (s) coated film (s) may be polyamine treated, in particular sprayed. Preferably, the outer paper (s) is treated.

The pressing pressure is typically below 100 bar, the pressing time is usually up to 90 minutes and the pressing temperature is usually at a maximum of 150 ° C. The correspondingly produced laminates are then glued to the wood material by methods known to the person skilled in the art.

In case (iv), application of the aqueous polymer solution to the open sites can be accomplished by various means known to those skilled in the art. These include, for example, spraying, rolling, knife coating, brushing or dripping. Preferably, the polyamine solution is applied by spraying. The surface-treated wood material may have an elevated temperature during application or be at room temperature; Further, the polyamine solution can have an elevated temperature or room temperature during application. Preferably, the application of the polyamine solution takes place under room temperature conditions.

On an industrial scale, for example, in the parallel drilling of holes, the device for applying, in particular spraying, the polyamine solution may be coupled to the device for drilling or arranged laterally offset therefrom. For example, can be integrated into a device for pledges of wood materials, a device for rolling or spraying the polyamine solution.

Wood-based materials are all materials which are made of wood strips, such as veneer boards or plywood boards, wood-based materials produced from wood chips, for example chipboard or OSB boards, and wood fiber boards. Materials such as LDF, MDF and HDF boards. These wood-based materials are produced from the corresponding wood particles with the addition of natural and / or synthetic binders by hot pressing. Advantageously, wood-based materials containing formaldehyde are produced by the process according to the invention. Preference is given to OSB, wood fiber and chipboard.

The wood-based materials can be surface-treated after pressing by grinding. The application of the polyamines according to the invention can be carried out before or after the grinding, preferably after grinding. The wood-based material may have an elevated temperature during application or may be at room temperature. The wood-based material can also be heat-treated after application, for example by infrared radiation, heated rollers or in a heat channel. The polyamines can be applied on one side or on both sides, preferably on both sides.

The invention further provides the wood materials obtainable by the process according to the invention, in particular formaldehyde-containing binders, optionally surface-refined wood-based materials. Preference is given to treated optionally surface-treated chipboard and wood fiber boards according to the invention.

The wood-based materials obtained by the process in the case of (i) and (ii) can then optionally be surface-treated. The surface finishing can be done by coating with different materials. For example, a coating, veneering, lamination or lamination can be carried out or a coating with melamine films, prepregs or films can be carried out. Such surface-treated wood materials are also the subject of the invention.

Thus, in addition to the optionally surface-refined wood-based materials which can be produced by the process according to the invention, the invention also relates to laminates which contain at least one polyamine-treated film selected from the group of the counteracting films, core films, decorative films or overlay films.

The wood material produced according to the invention advantageously has a formaldehyde emission of 0 to 0.1 ppm, preferably from 0 to 0.04 ppm, in particular from 0 to 0.02 ppm (EN 717-1 "Formaldehyde emission by the test chamber method"), or a formaldehyde emission of advantageously 0 to 3.5 mg / m ² h, preferably from 0 to 2 mg / m ² h, in particular from 0 to 1 mg / m ² h (EN 717-2 "Formaldehyde release by the gas analysis method").

The wood-based materials according to the invention can be used for the production of furniture, packaging materials, in building construction, in dry construction or in interior work, for example as a laminate, insulating material, wall or ceiling element. Examples

Case (i)

The tests were carried out with ground urea-formaldehyde glue-bonded chip slabs having a thickness of 16 mm and a density of 650 kg / m ³ .

treatment

Example 1: none (not according to the invention)

Example 2: pure urea solution (not according to the invention)

A 30% urea solution was applied to the chipboard in an amount that leads to a urea amount of 40 g / m ² , heated to 60 ° C for 150 seconds and then stored for 1 day at 20 ° C / 65% humidity.

Example 3: Polyethyleneimine solution (according to the invention)

A 30% aqueous solution of a polyethyleneimine having an average molecular weight of 5,000 g / mol was sprayed on the chipboard so that 40 g / m ^{2 of} polyethylenimine was applied to the chipboard. Thereafter, the surface was heated to 60 ° C. within 150 seconds and then stored for 1 day at 20 ° C./65% air humidity.

Example 4: Polyethyleneimine solution (according to the invention)

A 25% aqueous solution of a polyethyleneimine having an average molecular weight of 5,000 g / mol was sprayed onto the chipboard so that 5 g / m ^{2 of} polyethylenimine was applied to the chipboard. Subsequently, 1 day at 20 ° C / 65% humidity was stored.

Example 5: Adjustment of the formaldehyde scavenger of Examples 4 to 6 of JP 2002 273145 (Comparative Example)

An aqueous solution containing, according to J P 2002 273145, 50% by weight of a

Mixture of:

Urea 24% (active substance)

N, N-dimethylurea 1% (active substance) adipic acid dihydrazide 5% (active substance)

N, N-dimethylhydrazine 1% (active substance)

Benzylamine 1% (active substance) Triethanolamine 0.5%

Sodium di ethyl hexyl sulfosuccinate 1, 2% Sodium linol alcohol sulfonate 1%

Polyvinyl acetate emulsion (50%) 40% (20% dispersion + 20% water) (active substance)

Water 25.3% and 50 wt .-% water, ie a 26% aqueous solution (based on the active substances) was sprayed onto the chipboard, so that 5 g / m ^{2 of} active substance were applied to the chipboard. Subsequently, 1 day at 20 ° C / 65% humidity was stored.

Formaldehyde release:

Formaldehyde emission with or without aftertreatment was determined in accordance with the DIN standard DIN EN717-2 (Determination of formaldehyde release Part 2: Formaldehyde release by the gas analysis method) from 1994, and the DIN standard DIN-EN717-1 (determination of formaldehyde release Part 1: formaldehyde release according to the test chamber method) from the year 2004 and the DIN standard DIN-EN 120 (determination of the formaldehyde content: extraction method, called perforator method) from the year 1992 determined.

For the EN717-2, a test specimen measuring 0.4m x 0,05m x (thickness of the test specimen in m), with sealed narrow surfaces in a chamber with a volume of 0,004 m ³ at 60 ° C and 2 +/- 1 % relative humidity for 4 hours. The air flow is set to 60 l / h. For 1 hour each, the escaping air is collected in a gas wash bottle containing an aqueous solution of acetylacetone and ammonium acetate. Formaldehyde reacts in aqueous solution with ammonium ions and acetylacetone to diacetyldihydrolutidine (DDL). This reaction is highly specific for formaldehyde. The DDL has an absorption maximum at 412 nm and can be quantitatively detected by spectroscopy. To determine the formaldehyde concentration, the values for the last 3 hours are averaged.

According to the EN717-1, two test specimens with the dimensions 0.5 x 0.5 x thickness x in the ³ with 0.75 m open edge are placed in a test chamber with the volume 1 in the ³ . The measurement is carried out for at least 10 to a maximum of 28 days at 23 ° C and a relative humidity of 45 +/- 3%. The air intake and exhaust is chosen so that the entire air is replaced once within 1 hour. For sampling, 120 l of air are passed at a rate of 2 l / min into a gas scrubber bottle filled with aqueous ammonium acetate and acetylacetone solution. The formaldehyde concentration is also determined spectroscopically. The formaldehyde emission results from this method from a compensation curve, while 4 consecutive values may vary by no more than 5%. Is after 28 days If this condition is not fulfilled, the last 4 values are used for averaging.

The EN 120 uses test specimens measuring 25 mm x 25 mm x thickness. About 110 g of test specimen are added together with 600 ml of toluene to the flask with perforator attachment. The toluene is boiled. The formaldehyde is released in the perforator to the water and determined photometrically.

Table 1A: Results of Formaldehyde Release Measurements of Examples 1 to 3

Table 1 B: Results of Formaldehyde Release Measurements of Examples 1, 4 and 5

coatability

The chipboards 1-3 were coated after 24 h under standard conditions (20 ° C / 65% humidity) as follows:

A white decorative paper (80 g / m ² ) was impregnated with 100 g / m ^{2 of} a resin liquor of Kauramin impregnating resin 792 and hardener 529 (100: 0.3) and dried in the oven at 160 ° C. The resulting film is placed on the surface of the chipboard and pressed (190 ° C, 25 bar, 35 s). To stabilize the test piece, a counter pull film is simultaneously pressed on the back side.

To evaluate the coatability, a lattice test is carried out. To do this, use a razor blade to make two parallel four parallel cuts (0.5 cm apart) the surface is made so that a diamond-shaped pattern is created. In the corners of the diamonds, there is a partial flaking of the coating. The percentage of destroyed surface is determined. The smaller the value, the better the coatability of the chipboard.

Table 2: Results of the Coatability Experiments of Examples 1 to 3:

Case (iii)

Example 6: Veneering

A 0.6 mm beech veneer was coated on the underside with a) 10 g / m ² (3 g / m ² active substance) and b) 20 g / m ² (6 g / m ² active substance) of a 30% aqueous polyethylenimine. Solution (weight-average molecular weight of the polyethyleneimine: 5000 g / mol) sprayed and then dried.

100 g / m ^{2 of} a glue liquor consisting of 100 parts of Kaurit® glue 329 and 20 parts of Bonit® hardener 12926 were applied to a commercially available chipboard (thickness of 16 mm and density of 650 kg / m ³ ). The veneer was laid on and pressed at 105 ° C press temperature and a pressure of 0.6 N / mm ² . The pressing time was 100 seconds.

Example 7: Decorating film

Commercially available decor paper (70 g / m ² beech decor of the Fa. Süddekor) was cut to about 30 cm x 20 cm and by placing in a tin pan, which was filled with a Tränkharzlösung (about 55% with respect to melamine Formaldehyde resin Kauramin® impregnating resin 792, 0.3% hardener H 529, 0.1% Kauropal® 933 from BASF AG), impregnated. The resin application rate was adjusted by peeling off the paper over a wire bar. Subsequently, the soaked decorative paper was dried at 120 ° C in a laboratory oven. After drying, the weight of the decorative film was 120 g / m ² , the residual moisture was 6.5%.

The decorative film was coated on the underside with a) 10 g / m ² (3 g / m ² active substance) and b) 20 g / m ² (6 g / m ² active substance) of a 30% polyethyleneimine aqueous solution (weight average molecular weight of Polyethyleneimine: 5000 g / mol) sprayed and then dried. The polyamine-treated decorative film was pressed on a commercially available chipboard (thickness of 16 mm and density of 650 kg / m ³ ) by means of a laboratory press at 180 ° C, the pressing pressure was 25 bar and the pressing time was 30 seconds.

Example 8: Uranium-aftertreated wood material according to the prior art A 30% urea solution was applied to a commercial chipboard (thickness of 16 mm and density of 650 kg / m ³⁾ in an amount which resulted in a urea amount of 40 g / m ² ), heated to 60 ° C in 150 seconds and then stored for 1 day at 20 ° C / 65% humidity.

A white decorative paper (80 g / m ² ) was impregnated with 100 g / m ^{2 of} a resin liquor of Kauramin® impregnating resin 792 and hardener 529, in a ratio of 100: 0.3, and dried in the oven at 160 ° C. The film thus obtained was placed on the surface of the chipboard and pressed (190 ° C, 25 bar, 35 s). To stabilize the test piece, a counter pull film was simultaneously pressed on the back side.

Formaldehyde emission:

The formaldehyde emission of the coated and uncoated chipboards produced according to the examples was determined by gas analysis (EN 717-2). The results are summarized in Table 3.

Table 3: Overview of the formaldehyde emissions of the particleboard of Examples 6 to 8

PEI: polyethyleneimine U: urea

coatability:

To evaluate the coatability, a lattice test was carried out. For this purpose, two times four parallel line-shaped cuts (distance 0.5 cm) were made with the aid of a razor blade through the surface of the surface-finished chipboard according to Examples 2 and 3, so that a diamond-shaped pattern was formed. In the corners of the diamonds There was a partial flaking of the coating. The percentage of destroyed surface was determined. The smaller the value, the better the coatability of the chipboard. The results of the coatability are summarized in Table 4.

Table 4: Results of the Coatability Experiments of Examples 7 and 8:

Case (iv)

Example 9

The formaldehyde emission of a melamine-fiber coated chipboard (E1 chipboard, 400 mm × 50 mm × 16 mm) whose edges were closed with self-adhesive aluminum foil (0.014 in ² edge area) was measured by gas analysis (EN 717-2).

Example 10

Analogous to Example 9, the formaldehyde emission of a chipboard was measured which, apart from the fact that the edges had no aluminum foil coating, was identical to the chipboard from Example 9.

Example 1 1

The open edges of the chipboard of Example 10 were sprayed with a 20% by weight aqueous solution of polyethylenimine (weight-average molecular weight of polyethyleneimine: 5000 g / mol) in an amount of 4 g of polyethyleneimine / m ² edge surface. The formaldehyde emission was measured analogously to Example 9. Table 5: Results of the gas analyzes of Examples 9 to 11

Example 12

In the chipboard according to Example 9, 5 holes with a diameter of 5 mm and a penetration depth of 9 mm were drilled. The formaldehyde emission was measured analogously to Example 9.

Example 13

In an amount of 5 g of active substance polyethylenimine / m ² inner surface of the bore: With the clamping plate according to Example 12 were in the 5 holes a 5 wt .-% aqueous polyethylenimine solution (5000 g / mol weight-average molecular weight of the polyethylene lenimins) dripped (ie, in an amount of 0.72 g of solution per well). The formaldehyde emission was measured analogously to Example 9.

Table 6: Results of the gas analyzes of Examples 12 and 13

Claims

claims

1. A method for reducing the formaldehyde emission of wood materials by means

Application of nitrogen-containing compounds, characterized in that (i) a mixture is applied to the wood material, the at least one

Polyamine and optionally up to 20 wt .-%, based on the mixture containing urea;

(iv) polyamine is applied to the open areas; wherein the polyamines have a molecular weight of at least 500 g / mol and at least 6 primary or secondary amino groups.

2. The method according to claim 1, characterized in that the polyamine is applied as an aqueous polymer solution which is obtainable by mixing - based on the polymer solution -

(a) 1 to 99% by weight of polyamine (b) 0 to 5% by weight of additives for improving wettability

(C) 0 to 30 wt .-% additives for adjusting the pH

(e) 0 to 50% by weight of urea

and in addition to 100 wt .-% water, wherein the amounts refer to the beginning of the mixing.

3. The method according to claim 1 or 2, characterized in that the polyamine has a molecular weight of at least 800 g / mol and at least 6 primary or secondary amino groups.

4. The method according to any one of claims 1 to 3, characterized in that is used as the polyamine hyperbranched polyamine and / or polyvinylamine.

5. The method according to claim 4, characterized in that the hyperbranched polyamine has a weight average molecular weight of greater than 1,000 g / mol and a degree of branching greater than or equal to 0.1.

6. The method according to any one of claims 1 to 3, characterized in that is used as the polyamine polyvinylamine and / or polyethyleneimine.

7. Process according to claim 6, characterized in that the polyvinylamine has a weight-average molecular weight of 5,000 to 500,000 g / mol and the polyethyleneimine has a weight-average molecular weight of 500 to 100,000 g / mol.

8. The method according to any one of claims 1 to 7, characterized in that the amount of applied polyamine

(i) per square meter surface area of the wood-based material is between 1 g and 200 g; (ii) between 0,01 kg and 5 kg per 100 kg of chip or fiber cake;

(iii) per square meter of coating substrate is between 0.1 g and 100 g and / or

(iv) is advantageously between 0.05 g and 200 g per square meter surface area of the surface-treated wood material.

9. The method according to claim 2, characterized in that the aqueous polyamine min

(i) by spraying, rolling, dipping, knife coating or brushing on the

Wood material is applied; (ii) applied to or in the chips or fiber cake by means of spraying, rolling, knife coating or brushing, or by applying the aqueous polyamine solution to the conveyor belt prior to sprinkling the glued chips or fibers;

(iii) is applied to the coating substrate by means of spraying, rolling, dipping, impregnating, knife-coating or brushing and / or

(iv) applied to the open areas by means of spraying, rolling, knife-coating or brushing.

10. The method according to any one of claims 1 to 9, characterized in that as wood-based materials optionally containing formaldehyde-containing binder (s)

Funerholz, plywood, OSB, wood fiber and chipboard can be used.

1 1. A method according to any one of claims 1 to 10, characterized in that in the case (i) the wood material is heat treated ne after the application of the polyamine or polyamines.

12. The method according to claim 1, characterized in that in case (ii) the polyamine or the polyamine solution is applied together with the steam used for material preheating the press.

13. The method according to claim 1, characterized in that the chip or fiber cake is pressed to the wood material.

14. The method according to any one of claims 1 to 9, characterized in that melamine films, pre-impregnates, films, laminates or veneers are used as coating substrates.

15. The method according to any one of claims 1 to 9, characterized in that holes or uncoated surfaces or edges in case (iv) are aftertreated.

16. wood material, producible by the method according to any one of claims 1 to 15, which has a formaldehyde emission of 0 to 0.1 ppm.

17. Surface-finished wood material producible by a method according to any one of claims 1 to 15, which has a formaldehyde emission of 0 to 0.1 ppm.

18. Laminate preparable by a process according to any one of claims 1 to 15, comprising at least one polyamine-treated film selected from the group of the Gegenzugfilme, core films, decorative films or overlay films.

19. Use of the wood-based material according to claim 16 or 17 for the production of furniture, packaging materials, in the home, drywall or interior design.