RU2437755C2 - Method to reduce release of formaldehyde in wood materials - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to the method of reduction of formaldehyde release in wood materials by application of nitrous compounds. The method includes (i) application of a mixture, containing at least polyamine and, if required, up to 20 wt % carbamide relative to the mixture weight, onto a wooden material; (ii) application of polyamine on or into a formed stock of a wood chipboard or a fibrous carpet; (iii) application of polyamine onto a coating substrate, which is to be used for surface treatment, and/or (iv) application of polyamine onto open areas; besides, polyamine has molecular weight of at least 500 g/mol, and at least 6 primary or secondary amino groups.

EFFECT: method makes it possible to reduce release of formaldehyde without reduction of mechanical properties and coverage of wood materials, type and strength of surface treatment, release of formaldehyde via open sections of a wood material with treated surface.

10 cl, 6 tbl, 13 ex

Description

This invention relates to a method for reducing the emission of formaldehyde in wood materials by treatment with polyamines. Further in this invention we are talking about wood material obtained by the described method, as well as multilayer materials also obtained by the described method, and the use of these wood and multilayer materials for the manufacture of furniture, packaging materials or in the interior decoration of buildings.

Wood materials are a profitable and resource-saving alternative to solid wood and are of great importance especially for the production of furniture and as building materials. The raw materials are thin layers of wood of various thicknesses, wood shavings, sawdust or wood fiber from various species of wood. These parts or particles of wood are usually pressed using natural and / or synthetic binders, if necessary, with the addition of other substances to obtain flat or block forms of wood material.

Formaldehyde-containing adhesives, such as urea-formaldehyde resins or melamine-containing urea-formaldehyde resins, are often used as binders. Resins are prepared by polycondensation from formaldehyde with urea or melamine. To obtain good adhesive properties, as a rule, formaldehyde is added in excess. This can cause free formaldehyde to appear in the finished wood material. The hydrolysis of polycondensates may release additional formaldehyde. The free formaldehyde contained in the wood material and the formaldehyde released as a result of hydrolysis during the life of the wood material can be released into the environment.

In addition, the wood itself can release formaldehyde into the environment, especially after heat treatment. Coated wood materials generally show less formaldehyde emission than uncoated substrates (“Wood as Raw Materials and Billets,” Vol. 47, 1989, p. 227).

Formaldehyde above a certain limit value can cause allergies in people, irritation of the skin, respiratory tract or eyes. Therefore, the reduction of formaldehyde emissions in the building elements of the interior is an important task.

Reducing the emission of formaldehyde by adding a reduced amount of formaldehyde in production only leads to a relative result, because with a decrease in the concentration of formaldehyde, the adhesive properties of the binder deteriorate, in addition, hardening of the binder is significantly slowed down. This leads to an increase in the production cycle time (described in "Wood Materials and Adhesives", M. Danki, P. Nimz, Springer Berlin-Heidelberg, 2002, 251-302).

Another way to reduce formaldehyde emissions is to add formaldehyde trapping agents, such as urea, to wood particles or to formaldehyde resin. However, the disadvantage of this method is the slow curing rate of the resin. In addition, the mechanical properties of the products are adversely affected.

The release of formaldehyde from wood materials in recent years could be reduced by various means. For example:

J. Myers (Forest Products Journal 1986, Volume 36 (6), 41-51) gives an overview of possible ways: from the use of low molecular weight reagents that trap formaldehyde, such as urea or ammonia in solid form (for example ammonium carbonate), in an aqueous solution (for example, a urea solution) or in gaseous form (NH ₃ ) before coating acts as a physical barrier.

Aeration of wood materials, especially particle boards, with ammonia (RY AB method, Verko method), as well as spraying of particle boards with reagents that capture formaldehyde (Swedspan method) (E. Roffael and H. Mirtzsch, Adhesia, 1990) are of technical importance. 4, 13-19). In the Swedspan method (EP-B 0006486), chipboards are hot sprayed with an aqueous urea solution or solutions containing other substances that break down ammonia. The disadvantage is the worst coverage of chipboards processed in this way. When wood materials were aerated with ammonia (RY AV method, Verko method), the disadvantage was that formaldehyde emission again increases with increasing storage time (p. 16, E. Roffael and H. Mirtzsch, Adhesia 1999, 4, 13- 19).

WO 2004/085125 A2 describes a method for reducing the release of glued wood materials, with aldehyde and isocyanate-reactive substances being applied to the aligned edges lying vertically to the gluing direction. In this case, it is necessary to eliminate volatile harmful substances from both wood and binder. To do this, you can use substances with an amine or amide group, or hydroxyl-containing substances. Among them are called, for example, urea, guanamine, ethylamine, ethanolamine, proteins, alcohols and carbohydrates.

JP 2002-273145 A describes a method for reducing the emission of formaldehyde in compounds of wood elements, where several separate methods are used to reduce the emission of formaldehyde. The described formaldehyde trapping water reagent consists of 20-50 wt.% Urea and a non-volatile amine residue, a means to increase the permeability of wood so that the urea and non-volatile amine can penetrate the compound, and a film-forming solid, which becomes physical after drying on the compound of wooden elements a barrier to formaldehyde. This film may affect the coatability of the joining of wood elements. Polyalkylene polyamines are also described as non-volatile amines. By this class of substances is meant 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 adapting stoichiometry of formaldehyde-containing binders or adding reagents that trap formaldehyde, as well as various methods for the subsequent processing of wood materials, other measures are needed to reduce formaldehyde emissions from wood materials. Until now, the release of formaldehyde through open areas resulting from subsequent or additional surface treatment, for example, as a result of drilling, milling or sawing, has been neglected.

Such open areas may be, for example, openings in the prefabricated walls of the shelves or in the sections used to conveniently adjust the shelves in height relative to the floor. In addition, it may be the edges of the floor shelves, not directed into the living space, often with uncovered surfaces and, thus, open. In some floor shelves, even the entire underside remains uncoated, which thereby represents an open area through which formaldehyde is released.

In this regard, the objective of the present invention is to reduce the emission of formaldehyde from wood materials, without reducing the mechanical properties and coating of wood materials or their swelling value, which may occur, for example, as a result of a high concentration of urea in reagents that capture formaldehyde or due to application ammonium salts.

Another objective of the invention is to reduce the emission of formaldehyde from surface treated wood materials without adversely affecting hardening or quality, i.e. appearance and strength, surface treatment. In addition, the coating process must not be disturbed.

Therefore, the next objective of this invention is to reduce the emission of formaldehyde through exposed areas of wood material with a treated surface.

This problem is solved using a known method of reducing the emission of formaldehyde in wood materials by applying nitrogen compounds. The method considered in this invention is characterized in that

(i) a mixture containing at least polyamine and, if necessary, up to 20 wt.% urea relative to the weight of the mixture is applied to the wood material;

(ii) polyamine is applied to or in a molded chipboard blank or fiber carpet;

(iii) the polyamine is applied to a coating substrate that is used for surface treatment and / or

(iv) polyamine is applied to exposed areas;

moreover, the polyamine has a molecular weight of at least 500 g / mol, and at least 6 primary or secondary amino groups.

By the term "molded chipboard blank or fiber carpet" is meant scattered, glued sawdust or, respectively, fibers, possibly pre-compressed. A molded chipboard or fiber carpet is generally at least twice as thick as the finished wood material.

By the term “coating substrate” is meant, for example, amino resin films, in particular melamine films, pre-impregnations, foil, multilayer materials or plywood and the like.

The term "open areas" in the present invention means holes, open edges without coating or surface and the like, resulting, for example, from subsequent drilling, milling or sawing after surface treatment.

The polyamine can be applied in aqueous form or with the addition of a solvent. Preference is given to an aqueous solution of polyamine.

An aqueous polymer solution is preferably obtained by mixing - relative to the polymer solution -

(a) 1-99 wt.% polyamine

(b) 0-5 wt.% additives to improve wettability

(c) 0-30 wt.% additives to adjust the pH

(d) 0-30 wt.% of other additives, such as fungicides, hydrophobization agents, colorants, organic solvents

(e) 0-50 wt.% urea

and water in addition to 100 wt.%, and the specified amount refers to the moment of the start of mixing.

As component (a), a specific polyamine or mixtures of several polyamines can be used.

The aqueous solution of polyamine contains from 5 to 90 wt.% Polyamine, preferably from 10 to 75 wt.%, In particular from 15 to 45 wt.% Polyamine, particularly preferably 25-40 wt.% Polyamine, relative to the polymer solution.

Preference is given to polyamines with a molecular weight of at least 500 g / mol, in particular at least 800 g / mol, and at least 6, in particular with at least 10 primary or secondary amino groups. As polyamines, hyperbranched polyamines, in particular polyethyleneimine, or polyvinylamine, or mixtures thereof, are preferred.

By the term “hyperbranched polyamines” in this invention is meant highly functional, highly and hyperbranched polymers containing amino or amido groups.

As the hyperbranched polyamines, various highly functional, highly and hyperbranched polyamines with a weight average molecular weight of more than 500 g / mol, with a branched main chain, the degree of branching (Degree of Branching; DB) of more than 0.05, are used. Preferably, hyperbranched polyamines are used with a weight average molecular weight of more than 1.000 g / mol, preferably more than 1.500 g / mol, and especially with a molecular weight of from 1.500 to 200.000 g / mol. The degree of branching is about 0.1 or more. Preferably, the degree of branching of the hyperbranched polyamines is between 0.2 and 0.99, particularly preferably between 0.3 and 0.95, with a preference being given between 0.35 and 0.75. The definition of "Degree of Branching" (degree of branching) can be found in N. Frey et al., Acta Polym. 1997, 48, 30.

Preferably, the hyperbranched polyamines exhibit at least four functional end groups, preferably at least eight functional end groups, and at least twenty functional groups are particularly preferred. The number of functional groups in the upper direction is not fundamentally limited, however, the hyperbranched polyamines of the present invention more often have less than 500 functional end groups, preferably less than 300 functional end groups, in particular less than 150 functional end groups.

A method for producing hyperbranched polyamines is described, for example, in WO 1996/19537, WO 1999/16810, WO 2005/075541, WO 2005/044897, WO 2003/0066702 and an earlier German patent application under registration number 102005056592.1 and the title "Preparation and use of highly functional , highly or hyperbranched polylysines. "

It is preferable to use polycondensation and polyaddition products as hyperbranched polyamines, preferably polycarbamides, polyamides, polythiocarbamides, as well as combinations of mixed forms with one or more of these functional groups, such as polymidocarbonates and polymidothiocarbonates, polycarbonate (thiocarbonates), polycarbonates polythiocarbamide urethanes, polyester urea and polyester thiocarbamides, polyaminocarbamides and polyaminothiocarbamides, polycarbonate urea and polycarbonate mids and polycarbonathiocarbamides, polyether carbamides and ether thiocarbamides, polyamide urethanes, polyamide esters, polyamidoamines, polyamide carbonates, polyamide ethers, polyether urethanes, polyaminourethanes, polycarbonate urethanes, polyamide polyamides, polyaminoamines, polyamines .d. Polycarbamides, polythiocarbamides, polycarbamide-urethanes, polyamides, polyetheramides, especially polycarbamides, polycarbamide-urethanes, polyamides, and especially polyamides, are particularly preferred as super-developed polymers.

Of this, particular preference is given to polyethyleneimine or polyvinylamine or mixtures thereof.

The weight average molecular weight of polyvinylamine is preferably from 5.000 to 500.000 g / mol, preferably from 5.000 to 350.000 g / mol, in particular from 5.000 to 100.000 g / mol. The weight average molecular weight of polyethylenimine is preferably from 500 to 100,000 g / mol, preferably from 500 to 70,000 g / mol, particularly preferably from 500 to 50,000 g / mol, with even greater preference from 800 to 20,000 g / mol and with the most preference from 2,000 up to 20.000 g / mol.

Polyethyleneimine can be obtained by acid-catalyzed polymerization of ethyleneimine and, as a rule, its final product is obtained in the form of an aqueous solution containing from 20 to 100 wt.%, Preferably between 40 and 70 wt.%, Of polyethyleneimine. Polyvinylamine can be obtained by polymerization of vinylformamide and subsequent hydrolysis, its final product, as a rule, is obtained in the form of an aqueous solution from 2 to 50 wt.%, Preferably from 5 to 25 wt.%. The degree of hydrolysis can be determined using the reaction conditions, and specifically the ratio of amine groups to formamide groups. In most cases, these solutions can be used directly as the basis for the polyamine solutions of the present invention.

As optional components (b) of the aqueous polymer solution, ionic and nonionic surfactants can be used to improve the wettability, as described, for example, in H. Stäch, “Tensid-Taschenbuch” (Surfactants Handbook), Karl Hanzer, Munich, Vienna, 1981, in a preferred concentration of from 0 to 5 wt.%, Preferably from 0 to 2 wt.%.

The pH can be adjusted using the following additives as optional components (c): mineral or organic acids such as sulfuric acid or formic acid. Components (c) can be added to the aqueous polymer solution in an amount of 0-30 wt.%, Preferably from 0 to 20 wt.%.

As optional components (d), you can use other additives of the aqueous polymer solution, for example, additives from the group of water-repellent agents, for example, paraffin emulsions and waxes, fungicidal agents, organic solvents and dyes. Components (d) can be added to the aqueous polymer solution in an amount of from 0 to 30 wt.%, Preferably from 0 to 10 wt.%.

As optional components (e), aqueous polymer solutions may preferably contain up to 20% by weight of urea, depending on the polymer solution. Particular preference is given to an aqueous polymer solution with a carbamide content of less than 15 wt.%, Preferably less than 10 wt.%, And a carbamide content of less than 5 wt.%, Depending on the polymer solution, is particularly preferred. Urea-free polymer solutions are particularly preferred.

It is preferable to apply a polyamine solution with a pH value of from 3 to 12. In case (i), a polyamine solution with a pH value of from 7 to 11 is preferred, particularly preferably with a pH value of 9 to 11, and may have a less preferred acidity range place and protonation of polyamines. In cases (ii) and (iii) it is preferable to apply a polyamine solution with a pH value of 5 to 10, especially with a pH value of 6 to 8. In case (iv) it is preferable to apply a polyamine solution with a pH value of 6 to 11, in particular with a pH value of from 9 to 11.

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

In case (ii), a sufficient amount of a polyamine solution is applied so that the amount of polyamine per 100 kilograms of preformed chipboard or fiber carpet is preferably between 0.01 and 5 kg, preferably between 0.05 and 1 kg, particularly preferably between 0 , 1 and 0.5 kg.

In case (iii), a sufficient amount of a polyamine solution is applied so that the amount of polyamine per square meter of the coating substrate is 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 a polyamine solution is applied so that the amount of polyamine per square meter of the surface of the exposed surface wood material is preferably between 0.05 and 200 g, preferably between 0.1 and 50 g, especially preferably between 0, 3 and 30 g, and most preferably between 0.5 and 10 g.

An aqueous polymer solution can be applied to wood materials by various methods known to those skilled in the art (case (i)). These include, for example, spraying, rolling, dipping, applying by squeegee, greasing, applying by watering, it is preferable to apply a solution of polyamine by spraying or rolling.

The application of a polyamine or an aqueous solution of polyamine on a molded chipboard blank or fiber carpet can be made by various methods known to those skilled in the art (case (ii)). These include, for example, spraying, rolling, applying by squeegee, rolling, applying by irrigation, preference is given to applying an amine solution by spraying.

An aqueous solution of polyamine can be applied, for example, on the upper and / or lower side of the fibrous carpet. The application of a polyamine or an aqueous solution of a polyamine can be carried out at elevated temperature or at room temperature.

For example, a polyamine or an aqueous solution of polyamine can be applied before or after cold pressing / pre-compression. In a structure of a molded billet of a particleboard or fiber carpet of the type outer layer - middle layer - outer layer, polyamine or aqueous polyamine solution may be in one or more layers and / or between separate layers. It is preferable to apply the polyamine on the outer layer (s), preferably on both outer layers, of the molded billet of a chipboard or fibrous carpet.

The application of polyamine on the lower outer layer can be done, for example, indirectly by applying to the conveyor belt, which transfers the fibrous carpet to the press. In this case, the required amount of polyamine solution is applied to the conveyor belt, for example, by spraying or rolling, after which the shavings or fibers smeared with glue are poured onto the conveyor belt.

The polyamine or an aqueous solution of polyamine can be applied or sprayed, for example, together with steam intended for preheating the press material (see WO 2004/87388 and references inside the document).

A molded chipboard blank or a polyamine fiber carpet is pressed in a manner known to those skilled in the art in a wood material (cf. "MDF - Medium Density Fiberboard", Hans-Joachim Deppe, Kurt Ernet, 1996, DRW -Weinbrenner GmbH & Co., 70771 Leinfelden-Echterdingen, chapter 4.3, p. 81ff .; see also EP 1192223 B1, paragraph [0034] and “Handbook of chipboard technology” by Joachim Deppe, Kurt Ernst, 2000, DRW-Weinbrenner GmbH. & Co., 70771 Leinfelden-Echterdingen, chapter 3.5, pages 232ff).

In case (iii), the application of a polyamine or an aqueous solution of a polyamine on a coating substrate can be carried out by various methods known to those skilled in the art. These include, for example, sputtering, rolling, dipping, impregnation, application by means of a squeegee, lubrication, application by irrigation. Preference is given to a sprayed amine solution.

It is preferable to apply the polyamine solution on the back of the coating substrate, i.e. to the side facing the wood material.

The coating substrate is then pressed with wood material in a manner known to those skilled in the art.

For example, in the case of processing plywood, an aqueous solution of polyamine can be sprayed onto the underside of the plywood. After applying the adhesive solution to the substrate of a wood material, such as a chipboard, the plywood thus treated is laid and pressed under temperature and pressure.

For example, in the case of processing a melamine film, an aqueous solution of polyamine can

(A) apply before impregnation on paper, for example, decorative paper or paper coating,

(B1) add to the resin impregnation solution for pre-impregnation,

(B2) add to the resin impregnation solution for subsequent impregnation / coating,

(C) apply after impregnation of paper or

(D) Apply only after the impregnated paper has dried.

Preference is given to applying an aqueous solution of polyamine after the impregnated paper has dried.

Obtaining a resin film of substrates for coating or multilayer coating generally occurs by impregnation of paper, for example a) sulfate kraft paper with a paper weight between 50 and 150 g / m ² , b) decorative printed paper with a paper weight between 50 and 150 g / m ² or c) a paper coating with a paper weight of between 20 and 50 g / m ² using aqueous resin solutions, the paper being impregnated with a resin solution and / or a resin solution applied to the paper by squeezing or spreading. After that, the substrate is dried to a residual moisture / water content of 2 to 8%. In case a), a paper density of from 100 to 250 g / m ^{2 is} obtained, and in case b) and c) from 50 to 150 g / m ² .

Further, these dried substrates in case a), i.e. in the case of resin films, it is preferably sprayed with polyamine, dried and pressed into HDF (high density wood fiber board), MDF, particle board or the like. The pressing pressure is usually from 5 to 80 bar, the pressing time is generally less than a minute, usually from 10 to 30 seconds, the pressing temperature is in the range from about 160 to 200 ° C.

In case b), i.e. in the production of multilayer materials, if necessary, several films are sprayed, dried and pressed into a multilayer material. The multilayer material usually consists of several lagens of impregnated core paper, preferably from 2 to 15 sheets of core paper, one or more sheets of impregnated decorative paper and / or paper coating as a surface layer and, if necessary, one or more stabilizing sheets of paper, for example sulfate kraft paper. Polyamine can be processed, in particular sprayed, at choice all the layers used, only individual layers, only core paper or only film (s) intended for the boundary surface. Preference is given to the processing of the outer layer (s) of paper.

The pressing pressure is usually less than 100 bar, the pressing time is usually up to 90 minutes, and the pressing temperature, as a rule, does not exceed 150 ° C. Laminated materials produced in this way are glued to wood materials by methods known to those skilled in the art.

In case (iv), an aqueous solution of polyamine can be applied to exposed areas by various methods known to those skilled in the art. These include, for example, spraying, rolling, applying by means of a squeegee, spreading or dripping. It is preferable to spray the polyamine solution. Wood material, the surface of which is subjected to processing, when applied, can be room temperature or higher than room temperature; In addition, the polyamine solution may be at room temperature or above room temperature when applied. It is preferable to apply the polyamine solution under conditions below room temperature.

On an industrial scale, for example, when drilling holes in parallel, a device for applying, in particular spraying, a polyamine solution can be attached or attached to the side of the drilling device. For example, a device for rolling or spraying a polyamine solution can be integrated into a device for sawing building materials.

As wood materials, all materials made from wood strips are considered, such as, for example, plywood sheets or glued plywood sheets, wood materials from sawdust, for example, particle boards or oriented particle boards, such as wood fiber materials, for example, fiber boards of low, medium and high density. These wood materials are produced from the corresponding wood particles with the addition of natural and / or synthetic binders by hot pressing. By the method described in this invention, more often produce formaldehyde-containing wood materials, which include binders. More commonly oriented particle boards, fiberboards and particle boards.

The surface of wood materials can be ground after pressing. The polyamines referred to in this invention can be applied before or after grinding, preferably after. When applying polyamine, the wood material may have a higher, or maybe room temperature. The wood material after application can be subjected to heat treatment, for example, by means of infrared radiation, heated rolling or in a heated channel. Polyamines can be applied on one or on two sides, preferably on two.

In addition, the invention also relates to wood-based materials produced by the method described herein, in particular wood-based materials, preferably containing formaldehyde-containing binders, with a surface that has been processed if necessary. Preference is given to chipboard and fiberboard treated or with a surface treated by the method described in this invention.

The surface of wood materials obtained by the methods described in points (i) and (ii) can also subsequently be processed. The surface can be treated by coating with various materials. For example, varnishing, plywood sheathing, laminating or laminating or coating with melamine films, pre-impregnation agents or foil can be done. Wood materials whose surface has been treated of this kind are also the subject of this invention.

Thus, along with wood materials, the surface of which was treated by the methods described in this invention, and wood materials, which were produced by the methods described by this invention, the invention relates to multilayer materials containing at least one polyamine-treated layer from the group of stabilizing layers , middle layers, decorative layers or overlay layers.

Wood material produced in accordance with this invention typically has a formaldehyde emission of from 0 to 0.1 ppm, preferably from 0 to 0.04 ppm, more preferably from 0 to 0.02 ppm (EU 717-1 "Method for determining formaldehyde emissions in test chamber "), or the emission of formaldehyde, preferably from 0 to 3.5 mg / m ² h, more preferably from 0 to 2 mg / m ² h, particularly preferably from 0 to 1 mg / m ² h (EC 717-2" Determination of formaldehyde emissions by gas analysis ").

The wood materials of this invention can be used for the manufacture of furniture, packaging materials, in the construction of houses, in the production of dry work or in interior decoration, examples of this are laminate, insulation material, ceiling or wall elements.

Examples

Case (i)

We studied polished wood chipboards with a urea-formaldehyde-adhesive compound 16 mm thick and a density of 650 kg / m ³ .

Treatment

Example 1: none (not in accordance with this invention)

Example 2: pure urea solution (not in accordance with this invention)

A 30% aqueous urea solution was applied to the chipboard in an amount that resulted in a urea content of 40 g / m ² , heated to 60 ° C for 150 s and then held for one day at a temperature of 20 ° C / air humidity 65 %

Example 3: a solution of polyethyleneimine (in accordance with this invention)

A 30% aqueous solution of polyethylenimine with an average molecular weight of 5.000 g / mol was sprayed onto the particle board in such a way that 40 g / m ^{2 of} polyethyleneimine was applied to the particle board. Finally, the surface was heated to 150 ° C for 150 s and held for 1 day at a temperature of 20 ° C / 65% air humidity.

Example 4: a solution of polyethyleneimine (in accordance with this invention)

A 25% aqueous solution of polyethyleneimine with an average molecular weight of 5.000 g / mol was sprayed onto a particle board in such a way that 5 g / m ^{2 of} polyethyleneimine was applied to the particle board. Then they stood for 1 day at a temperature of 20 ° C / humidity of 65%.

Example 5: Regulation of a formaldehyde trapping reagent in Examples 4-6 of JP 2002 273145 (comparative example)

An aqueous solution containing in accordance with JP 2002273145 50 wt.% A mixture of:

urea: 24% (active substance)

N, N-dimethylcarbamide: 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 sulfonate-linoleic alcohol: 1%

polyvinyl acetate emulsion (50%): 40% (20% of the ingredients of the mixture + 20% of water) (active substance)

water: 25.3% and 50 wt.% water, i.e. A 26% aqueous solution (depending on the active substances) was sprayed onto the particle board in such a way that 5 g / m ^{2 of the} active substance was applied to the particle board. Then they stood for 1 day at a temperature of 20 ° C / humidity of 65%.

Formaldehyde emission:

Formaldehyde emission with or without further processing is determined in accordance with DIN EN717-2 (Determination of formaldehyde emission, part 2: determination of formaldehyde emission by gas analysis) 1994, and the German Institute for Standardization DIN EN717-1 (Determination of formaldehyde emission, part 1 : a method for determining the emission of formaldehyde in a test chamber) of 2004 and the standard of the German Institute for Standardization DIN EN 120 (Determination of formaldehyde content: extraction method called the punch method) 1992

EN717-2 examines a test specimen with dimensions of 0.4 m × 0.05 m × (sample thickness in m), with closed narrow surfaces in a chamber with a volume of 0.004 m ³ at a temperature of 60 ° C and a relative humidity of 2 +/- 1% for 4 hours. The air flow is set at 60 l / h. In each case, outflowing air is collected within 1 hour into a gas-washing bottle, which contains an aqueous solution of acetylacetone and ammonium acetate. Formaldehyde reacts in an aqueous solution with ammonium ions and acetylacetone to diacetyldihydrodimethylpyridine (DDL). This reaction is highly specific for formaldehyde. DDL has an absorption maximum of 412 nm and its amount can be determined spectroscopically. To obtain the formaldehyde concentration, the values of the last 3 hours are averaged.

In accordance with EN717-1, two test samples with dimensions of 0.5 × 0.5 × thickness in m ² with an open edge of 0.75 m are installed in a chamber of 1 m ³ volume. The measurement is carried out for a minimum of 10 - a maximum of 28 days at a temperature of 23 ° C and a relative humidity of 45 +/- 3%. The air inlet and outlet is selected in such a way that within 1 hour, all air changes completely once. To take samples, conduct 120 l of air at a speed of 2 l / min, in a gas-flushing bottle filled with an aqueous solution of ammonium acetate and acetylacetone. The formaldehyde concentration is again determined spectroscopically. As a result, formaldehyde emission is obtained in accordance with this method from the alignment curve, while 4 consecutive values may differ by a maximum of 5%. If after 28 days this condition is still not satisfied, the last 4 values are taken to form the average value.

EN120 uses samples with dimensions of 25 mm × 25 mm × thickness. Test samples of approximately 110 g are added along with 600 ml of toluene to the flasks with a perforator. Toluene is brought to a boil. Formaldehyde in a perforator is released into water, it is determined photometrically.

Table 1A: Formaldehyde emission measurement results in Examples 1-3 Plate Post processing Gas analysis (EN 717-2) Camera value 1 m ³ (EN 717-1) Example 1 no 2.3 mg / m ² h 0.042 ppm Example 2 40 g / m ² of urea (30% aqueous solution) 1.7 mg / m ² h 0.021 ppm Example 3 40 g / m ² polyethyleneimine (30% aqueous solution) 0.1 mg / m ² h <0.001 ppm

Table 1B: The measurement results of formaldehyde emission in examples 1, 4 and 5 Plate Post processing Perforator [mg / 100 g] Example 1 no 5.1 Example 4 5 g / m ² polyethyleneimine (25% aqueous solution) 0.3 Example 5 5 g / m ² active substance according to JP 2002 273145, examples 4-6 (26% aqueous solution) 4.6

Coverage

On chipboards 1-3 after 24 hours of exposure under normal conditions (20 ° C / 65% air humidity), the coating was applied as follows.

The white decorative paper (80 g / m ² ) is impregnated with 100 g / ² polymer solution of Kauramin 792 impregnation resin and hardener 529 (100: 0.3) and dried in an oven at a temperature of 160 ° C. The film thus obtained is laid out on the surface of a chipboard and pressed (190 ° C, 25 bar, 35 s). To stabilize the test specimen, a stabilizing film is pressed onto the back side at the same time.

To assess coverage, a grid test is performed. To do this, four parallel linear cuts (a distance of 0.5 cm) are made twice through the surface with a blade, so that a diamond-shaped sample is obtained. In the corners of the rhombus, partial peeling of the coating occurs. Determine the percentage of damaged surface. The lower the value, the better the coverage of the particle board.

Table 2: The coverage test results of examples 1 to 3: Plate Additional processing The surface damaged after the test with a grill, in% Example 1 no 10 Example 2 40 g / m ² of urea (30% aqueous solution) 35 Example 3 40 g / m ² polyethyleneimine (30% aqueous solution) 5

Case (iii)

Example 6: Plywood cladding

0.6 mm beech plywood was sprayed from the underside of a) 10 g / m ² (3 g / m ^{2 of} active substance) and b) 20 g / m ² (6 g / m ^{2 of} active substance) with 30% aqueous polyethyleneimine solution (weight average molecular weight polyethyleneimine: 5000 g / mol), and then dried.

100 g / m ^{2 of} adhesive from 100 parts of Kaurit® 329 glue and 20 parts of Bonit® 12926 hardener were applied to a standard chipboard (thickness 16 mm and density 650 kg / m ³ ). We applied plywood and pressed it at a pressing temperature of 105 ° C and a pressing pressure of 0.6 N / mm ² . The pressing time was 100 seconds.

Example 7: decorative film

Standard decorative paper (70 g / m ² Buche-Dekor from Süddekor) was cut into pieces of approximately 30 cm × 20 cm, impregnated in a tin bath filled with a solution of impregnation resin (approximately 55% Kauramin melamine-formaldehyde resin impregnation resin ® 792, 0.3% hardener H 529, 0.1% Kauropal® 933 from BASF AG). The amount of resin applied was determined by straightening the paper on a wire squeegee. Then, the impregnated decorative paper was dried at a temperature of 120 ° C in a laboratory oven. After drying, the weight of the decorative film was 120 g / m ² , the residual humidity was 6.5%.

On the underside of the decorative film, a) 10 g / m ² (3 g / m ³ active substance) was sprayed and b) 20 g / m ² (6 g / m ² active substance) with a 30% aqueous solution of polyethyleneimine (weight average molecular weight polyethyleneimine: 5000 g / mol) and then dried.

The polyethyleneimine-treated decorative film was pressed onto a standard chipboard (thickness 16 mm and density 650 kg / m ³ ) using a laboratory press at a temperature of 180 ° C, the pressing pressure was 25 bar, and the pressing time was about 30 seconds.

Example 8: Wood material subsequently treated with urea, in accordance with the prior art

A 30% aqueous urea solution in an amount that led to a urea content of 40 g / m ² was applied to a standard chipboard (thickness 16 mm and density 650 kg / m ³ ), heated to 60 ° C after 150 seconds, then kept for 1 day at a temperature of 20 ° C / humidity of 65%.

White decorative paper (80 g / m ² ) was impregnated with 100 g / m ² resin solution from Kauramin® 792 impregnation resin and hardener 529, in a ratio of 100: 0.3, and dried in an oven at a temperature of 160 ° C. The film thus obtained was laid out on the surface of a chipboard and pressed (190 ° C, 25 bar, 35 s). To stabilize the test sample, a stabilizing film was pressed on the back side at the same time.

Formaldehyde emission:

The emission of formaldehyde in the coated and uncoated particle boards produced according to the examples was determined by gas analysis (EC 717-2). The results are shown in table 3.

Table 3: Summary table of formaldehyde emissions in particle boards of examples 6 to 8 Coating material Formaldehyde Reagent Treatment Gas analysis in accordance with EU 717-2. Edges closed [mg formaldehyde / m ² h] without without 6.0 decorative film without 1,2 decorative film 3 g / m ² REI 0.5 decorative film 6 g / m ² REI 0.3 decorative film 40 g / m ² U 0.6 plywood without 4.1 plywood 3 g / m ² REI 2.9 plywood 6 g / m ² REI 2,4 PEI: polyethyleneimine U: urea

Coverage:

To determine the coverage, a grid test was performed. To do this, the blade was made four times four parallel linear cuts (distance 0.5 cm) through the surface of the particleboard with the treated surface according to examples 2 and 3, to obtain a diamond-shaped sample. In the corners of the rhombuses, the coating partially receded. The percentage of damaged surface was determined. The lower the value, the better the coverage of the particle board. The results of coverage are shown in table 4.

Table 4: The test results for the coatability of examples 7 and 8: Example Formaldehyde Reagent Treatment The surface damaged after the test with a grill, in% no 10 7 6 g / m ² polyethyleneimine (30% aqueous solution) 10 8 40 g / m ² of urea (30% aqueous solution) 35

Case (iv)

Example 9

The emission of formaldehyde by a particleboard coated with a melamine film (E1 is a particleboard, 400 mm × 50 mm × 16 mm) with edges covered by a self-adhesive aluminum film (0.014 m ² edge area) was measured using gas analysis (EN717 -2).

Example 10

Analogously to example 9, the formaldehyde emission was measured with a particle board, which, except that there was no aluminum film coating at the edges, was identical to the particle board from example 9.

Example 11

The open edges of the particle board of Example 10 were sprayed with a 20% by weight aqueous solution of polyethyleneimine (weight average molecular weight of polyethyleneimine: 5000 g / mol) in an amount of 4 g of active substance polyethyleneimine / m ² edge area. Formaldehyde emission was measured as in Example 9.

Table 5: The results of gas analysis of examples 9 to 11 Examples Gas analysis [mg / m ² h] 9 0.9 10 3.2 eleven 1,1

Example 12

In a chipboard, as in Example 9, 5 holes were drilled with a diameter of 5 mm and a drilling depth of 9 mm. Formaldehyde emission was measured as in Example 9.

Example 13

A 5% by weight aqueous solution of polyethyleneimine (weight average molecular weight of polyethyleneimine: 5000 g / mol) was added dropwise into 5 openings of a particle board, as in Example 12, in an amount of 5 g of active substance of polyethyleneimine / m ^{2 of the} inner surface of the drilled holes (i.e., in the amount of 0.72 g of solution per drilled hole). Formaldehyde emission was measured as in Example 9.

Table 6: The gas analysis results of examples 12 and 13 Examples Gas analysis [mg / m ² h] 12 1,5 13 0.9

Claims (10)

1. The method of reducing the emission of formaldehyde in wood materials by applying nitrogen compounds, characterized in that
(i) a mixture containing at least one polyamine and, if necessary, up to 20 wt.% urea based on the mixture is applied to the wood material, the application being carried out by spraying, rolling, dipping, by means of a doctor blade or brushing;
(ii) a polyamine is applied to or into a molded chipboard blank or fiber carpet, the application being carried out by spraying, rolling, by means of a squeegee, smearing, or onto the conveyor belt before applying the polyamine coated with glue sawdust or fibers;
(iii) a polyamine is applied to the coating substrate used to refine the surface, the application being carried out by spraying, rolling, dipping, soaking with a squeegee or smearing and / or
(iv) a polyamine is applied to exposed wood material, the application being carried out by spraying, rolling, by means of a doctor blade or brushing;
moreover, polyethyleneimine with a molecular weight of at least 500 g / mol and at least 6 primary or secondary amino groups is used as a polyamine. 2. The method according to claim 1, characterized in that the polyamine is applied in the form of an aqueous polymer solution obtained by mixing
- relative to the solution -
(a) 1-99 wt.% polyamine;
(b) 0-5 wt.% additives to improve wettability;
(c) 0-30 wt.% additives to adjust the pH;
(d) 0-30 wt.% of other additives, such as fungicides, hydrophobization agents, colorants, organic solvents;
(e) 0-50 wt.% urea
and water up to 100 wt.%, moreover, the indicated amounts relate to the moment of the start of mixing. 3. The method according to claim 1 or 2, characterized in that the polyethyleneimine has a molecular weight of from 500 to 100,000 g / mol. 4. The method according to claim 1 or 2, characterized in that the polyamine has a molecular weight of from 800 to 100,000 g / mol and at least 6 primary or secondary amino groups. 5. The method according to claim 1 or 2, characterized in that the amount of applied polyamine is
(i) from 1 to 200 g per square meter of wood material surface;
(ii) from 0.01 to 5 kg per 100 kg of a particleboard or fiberboard blank;
(iii) from 0.1 to 100 g per square meter of substrate coating and / or
(iv) preferably from 0.05 to 200 g per square meter of surface area of the exposed area of the treated wood material. 6. The method according to claim 1 or 2, characterized in that the wood material is used, if necessary, containing formaldehyde-containing binders, plywood, glued plywood, oriented particle boards, wood-fiber boards and particle boards. 7. The method according to claim 1, characterized in that in case (i) after applying the polyamine or polyamines, the wood material is subjected to heat treatment. 8. The method according to claim 1, characterized in that in case (ii) a polyamine or a polyamine solution is applied together with the steam used to preheat the press material. 9. The method according to claim 1 or 2, characterized in that melamine films, preliminary impregnations, foil, laminates or plywood are used as coating substrates. 10. The method according to claim 1 or 2, characterized in that in case (iv) the open areas are holes, uncoated surfaces or edges.