DE102015210569A1 - Increasing the reactivity of isocyanate adhesives by amine / ammonium compounds - Google Patents

Abstract

The present invention relates to a process for producing wood-based materials, comprising the steps, preferably comprising the steps of: (i) providing lignocellulose-containing material containing 5-40% by weight of lignins and 15-95% by weight of holocellulose; (ii) contacting the material of step (i) with a binder system comprising at least the following components: (a) at least one isocyanate group-containing component, (b) at least one component not in situ from the at least one Isocyanate group-containing component is produced, and is selected from the group consisting of ammonia; Compounds having a primary amino group; NH4 + salts; and primary ammonium salts, wherein the primary ammonium salts are not ammonium salts of the dithionic acid, (c) optionally lignins and / or tannins, and (d) optionally, solvents; wherein the binder system contains the at least one isocyanate group-containing component in an amount of at least 50% by weight, based on all polymerizable components of the binder system; wherein only the lignocellulosic material and optionally lignins and / or tannins are used as the hydroxy group-containing component (s) in the process to obtain a mixture; and (iii) thermally, thermomechanically or mechanically curing the mixture of step (ii) to obtain a wood material. In addition, the invention relates to a wood material, produced or producible by the method according to the invention.

Description

The present invention relates to a process for the production of wood-based materials, in particular comprising the steps of contacting lignocellulose-containing material with a binder system and curing the binder, the lignocellulose-containing material and the binder system being as defined in the claims.

State of the art

In Germany alone 10.5 million m ³ / year of wood-based materials are produced, of which 53% are particle board, 34% fiberboard, 11% OSB board and 2% plywood, ie about 6 million m ³ / year chipboard produced in Germany , In Europe (excluding Russia and Turkey) about 47 million m ³ / year wood materials are produced, of which 60% are chipboard, 23% MDF, 7% OSB, 6% plywood, 4% insulation boards.

In the wood-based panel industry, in addition to condensation resins such as urea-formaldehyde (UF), melamine-urea-formaldehyde (MUF) and phenol-formaldehyde (PF), isocyanate binders are also used for the production of wood-based materials (fiberboard, chipboards, insulating materials). On the one hand, these are mainly used in wet areas (eg particle boards after EN 312-5 or 7 ), on the other hand also used for "formaldehyde-free" glued panels. Even with hard to glue annual plants, such. As straw or bagasse, they are used.

An advantage of isocyanate adhesives, i. H. Binders based on isocyanate group-containing components, such as. As the polymeric diphenylmethane diisocyanate (PMDI), the good wetting behavior of wood surfaces and good penetration is compared to aqueous amino or phenol condensation resins.

Another advantage of isocyanate binders over formaldehyde resins is that they have no formaldehyde emissions. In addition, they are moisture resistant, thus reducing the use of paraffins and the products can be used both outdoors and in the wet area.

In contrast, the relatively low reactivity of the isocyanate adhesives represents a major disadvantage. When using PMDI as a binder for the production of wood-based materials such as particleboard and fiberboard or "Oriented Strandboards" (OSB) is therefore when using PMDI significantly lower machine speed of the presses hazards. A disadvantage of isocyanate resins compared to formaldehyde resins are therefore the increased costs. Although the amount of binder is reduced when using isocyanate adhesives due to the better wetting behavior, but their total use is still more expensive.

The binder used for wood-based materials is the corresponding isocyanate (PMDI) alone, without a reaction partner having an amino or hydroxyl group. The actual binder after curing is a polyaddition product formed from an isocyanate (di-, polyisocyanate) and an amino compound (di-, polyamine) (shown below).

Since only the isocyanate is used in the bonding by means of isocyanate adhesive, amino groups must be formed from this by reaction with water. This is done by adding water to the adhesive system, or by bound water of wood chips or fibers. The addition of water to an isocyanate group initially leads to the formation of a carbamic acid group, which, due to its low stability, splits off carbon dioxide and thus liberates an amino group (shown below).

The addition reaction shown below requires a relatively high activation energy, which leads to a slowing down of the reaction rate of the overall process.

The prior art also frequently describes the use of polyurethane adhesives. In this case, polyols are reacted with isocyanates. The process according to the invention does not include such polyurethane adhesives. Only the naturally occurring aromatic polyols, ie lignins and tannins, polyurethane compounds according to the invention - as far as they are stable under the curing conditions - form. However, this approach is fundamentally different from the conventional use of polyols (ie, hydroxy group-containing components) to form polyurethanes. The process according to the invention is thus characterized in that only the lignocellulose-containing material and optionally lignins and / or tannins as hydroxy-group-containing component (s) in the process used or used. If a natural, lignocellulosic material, other than lignins and tannins, would contain other polyols, the uses of the material containing these components would not be excluded, but these components will not be active in the process, e.g. In the provision of the lignocellulosic material or as part of the binder system.

A process for producing composites with minimized formaldehyde emission is disclosed by US Pat DE19522951A1 (1994). Here, material parts are impregnated with an aqueous formaldehyde-containing precondensed resin. As formaldehyde scavengers, ammonium carbonate and PMDI are mentioned in a list of compounds. The formaldehyde scavenger is used in small amounts of about 1-10 wt .-%, based on the amount of solid resin, and not as a binder. To ensure the action of the formaldehyde scavenger, it is preferable to add a catalyst capable of facilitating the thermal decomposition of the formaldehyde scavenger and / or the removal of the released formaldehyde and / or accelerating the curing of the formaldehyde resin. Suitable catalysts are ammonium salts, such as ammonium chloride or sulfate or Lewis acids, including known, suitable catalysts. The use of reactive -NH ₂ or -NH ₃ groups to activate an isocyanate binder which is used in substantially larger quantities than a formaldehyde scavenger is not described.

DE10356767A1 describes a process for the production of boards and moldings based on polyurethane binders. For the crosslinking of the polyurethane backbone (including polyisocyanates), the trimerization reaction of the isocyanate groups with itself or with urethane and urea groups can also be carried out to allophanate or biuret groups. For this purpose, trimerization catalysts can be used, such as. For example, DABCO TMR-2 is named Air Products, which are substituted quaternary ammonium salts dissolved in ethylene glycol, without reactive -NH ₂ or -NH ₃ groups. However, these -NH ₂ (primary amine) or -NH ₃ (ammonium) groups are necessary for accelerated curing of the isocyanate group-containing component according to the method of the present invention.

DE2711958A1 (1977) describes a process for binding or impregnating lignocellulose-containing raw materials by means of polyphenyl polymethylene polyisocyanates. In the process, catalysts can also be used, for. As tertiary amines such as triethyleneamine, secondary amines such as dimethylamine, metal compounds such as tin (II) acetate or nitrogen-containing bases such as tetraalkylammonium or alkali metal hydroxides (NaOH ..). These polyisocyanate mixtures can also be used in conjunction with customary binders, such as formaldehyde-containing binders or sulfite waste liquors or tannins. The method can be used for the production of wood-based materials. As with the DE10356767A1 , is also in the DE2711958A1 no use of -NH ₂ or -NH ₃ groups described.

EP2062708 A2 describes a method for reducing the emission of saturated and unsaturated aldehydes from wood-based materials. The task was to provide additives to reduce emissions of VOCs and formaldehyde.

These are reducing agents such. B. Formamidinsulfinsäure, salts of H ₂ S ₂ O ₄ (thionic acid), such as. For example, sodium dithionite, ammonium dithionite and Zinkthionit. Ammonium hydroxide is used to increase the pH. The process of the present invention based on the combination of an isocyanate group-containing component (as the main component of the binder system having at least 50% by weight based on the polymerizable components) with a component selected from the group consisting of ammonia; Compounds having a primary amino group; NH ₄ ⁺ salts; and primary ammonium salts to achieve accelerated binder cure is not described. The use of reducing agents, in particular salts of dithionic acid, is neither necessary nor desirable in the process according to the invention. In particular, the use of salts of dithionic acid (MS ₂ O ₄ , where M is a metal or ammonium) can lead to the formation of undesirable, especially corrosive, sulfur products such as SO ₂ or sulfurous acid. Oxidizing agents are neither necessary nor desirable in the process according to the invention.

EP2193899A1 and EP2644340A1 describe the use of, inter alia, ammonium persulfate as an oxidative addition agent for reducing emissions of VOCs and formaldehyde in the manufacture of wood-based materials. In addition, thionous salts are claimed as reducing agents. An application for accelerated production of wood materials is not described. The use of reducing agents or sulfur-containing compounds in general, in particular salts of dithionic acid, formamidinesulfinic acid or a combination of bisulfite salt and sulfite salt is neither necessary nor desirable in the process according to the invention. Even though EP2062708 A2 . EP2193899A1 and EP2644340A1 disclosed a variety of adhesives, including adhesives based on PMDI, as the disclose Neither the use of an adhesive with at least 50 wt .-% PMDI, nor an adhesive that explicitly contains no hydroxy group-containing component. This hydroxy group-containing component (eg, a polyol) is common in curing the adhesives to polyurethanes.

DE10 2007 038 085 A1 describes a process for the preparation of hard coating systems based on aqueous polyurethane dispersions, ammonia is described as one of many neutralizing agents. The document also does not disclose the use of an adhesive having at least 50% by weight PMDI, nor an adhesive which explicitly does not contain a hydroxy group-containing component.

DE19959170 A1 describes a process for the preparation of aqueous polyurethane dispersions as a modified prepolymer mixing process (PMP), in particular of self-emulsifiable aqueous polyurethane resins. PMP has mechanical disadvantages due to the more or less uncontrollable reaction kinetics. To obtain a useful property profile, large amounts of low molecular weight diols are needed, which in turn results in an increased need for hydrophilic groups. When using large amounts of hydrophilic groups (trialkylammoniumcarboxylate) for stabilization, problems occur in the stage of dispersion of the polyurethane prepolymer. The balanced trialkylamine (neutralizing agent) accelerates the isocyanate / water reaction extremely, whereby a large part of the free isocyanate groups is lost in a short time. The processing time of the polyurethane prepolymer between the beginning of the dispersion and the end of the chain extension with polyamines is thus drastically limited. When exceeding the processing time, the chain extender may no longer be completely installed. In addition to tertiary amines, ammonia is also used as neutralization component, but not for acceleration. These self-emulsifying, aqueous polyurethane resins can be used in the construction sector as binders for one-component and two-component coatings, sealants, adhesives, paints or membranes, sports floor coverings and sealants for the surfaces of mineral building materials such as concrete, gypsum, cement, as well as glass, wood, paper, metal or plastic are used. The application for the production of wood-based materials and the shortening of the pressing and production times is not described. In particular, the present invention does not relate to polyurethane compounds as described in US Pat DE19959170 A1 are described.

The DE19812751 A1 describes a solvent-free polyurethane dispersion with a high solids content of polyurethane polymer or fillers and their use in the construction sector for one-component, isocyanate- and solvent-free coatings, sealants, adhesives or membranes. The chain extension of polyurethanes is usually realized with water, but this leads to products with lower storage stability and reproducibility. The neutralization component described is ammonia and preferably tertiary amines. Use of the polyurethane dispersion in the construction sector for one-component, isocyanate-free and solvent-free coatings, sealants, adhesives, lacquers, or membranes for the surfaces of mineral building materials, such. As concrete, gypsum, cement, and glass, wood and wood materials, paper, metal and plastic. In particular, the present invention does not relate to polyurethane compounds as described in US Pat DE19812751 A1 are described.

In view of the findings to date, there continues to be a great need for suitable methods for producing wood-based materials, in particular for cost-effective methods which permit a high production speed. These objects are achieved by the method according to the invention.

Summary of the invention

The invention makes it possible to accelerate the production of composites and in particular wood-based materials, OSB and USB boards, fiberboard, MDF, HDF, insulation boards and insulating materials) with isocyanate binder, by using components which have or form at least two isocyanate-reactive nitrogen hydrogen atoms For example, ammonia, primary amines and primary ammonium compounds. Preference is given to using ammonium bicarbonate and ammonium carbonate.

The use of ammonium compounds produces ammonia in the reaction medium. This is more nucleophilic than water and thus reacts faster with the isocyanate groups, which leads to an acceleration of the crosslinking of the binder. Preference is given to using ammonium carbonate or ammonium bicarbonate. Both decompose completely at approx. 60 ° C into ammonia, carbon dioxide and water. The ammonia gas released during the thermal decomposition leads to an accelerated hardening of isocyanate binder.

The acceleration of the reaction of the isocyanate-containing binder in the production of wood-based materials is an economic advantage. This allows more plates to be produced at the same time without major investment. This is particularly relevant for chipboard and fibreboard manufacturers. In addition, the better reacting could result in a saving of the amounts of wood and binder quantities, which would be of interest to all manufacturers.

An unexpected advantage of the present invention for the production of wood-base materials results from the fact that the lignin present in the lignocellulose-containing (starting) material contains hydroxyl groups. Isocyanates are believed to react with hydroxyl groups of lignin in wood-base manufacturing. However, the resulting urethane bonds do not appear to be stable at higher temperatures (120 ° C) and prolonged exposure to temperature (see Dunky and Niemz 2002 ). However, by using ammonium salts as a reaction accelerator, the curing temperature can be lowered to significantly lower temperatures, so that these urethane formations are less decomposed. It could thus be produced materials with different product properties.

The present invention could increase the production capacity of existing plants without the need for large additional investment.

Ammonia and ammonium compounds may be added to the Isocyanatbindemittel-water mixture or by spraying separately on the wood fiber and chips, z. B. by separate nozzles. They accelerate the curing or hardening of the isocyanate binder and reduce the energy required. Thus, lower temperatures (eg 80 ° C) and in particular lower pressing times can be used.

The object of the invention is the acceleration of the overall process, ie the formation of polyurea, at significantly lower temperature (ie, lower amount of heat necessary to cure the isocyanate adhesive) by addition of ammonium compounds, primary amines or ammonia to the isocyanate group-containing component, eg. B. an isocyanate component-water mixture. The resulting binder (polymer) contains biuret groups and (poly) urea groups. The latter arise because not all isocyanate groups with z. B. NH ₃ , but also some react according to the conventional mechanism with amino groups, which are released from isocyanate groups. The proportion of biuret groups and polyurea groups depends on the ratio of the isocyanate used to the ammonium compound.

Ammonium is a weak acid in chemical equilibrium with ammonia (see below). The gaseous ammonia is more nucleophilic than water and reacts faster with isocyanate groups than with water to form a urea derivative (see below). Although the isocyanate (PMDI), as described above, penetrates very well into the wood, it can easily be achieved by the gaseous ammonia. The terminal amino group of the urea derivative is capable of reacting directly with another isocyanate group to form a biuret group (see below). The three NH groups of the biuret structure can further react with an isocyanate group, leading to branching or crosslinking.

Addition of the ammonia, which is formed from the ammonium salt, to the isocyanate group avoids (at least in part) the "detour" of water addition and decarboxylation. In addition to the addition of an ammonium salt, it is also possible to accelerate the reaction by the direct addition of ammonia (NH ₃ ). However, this can lead to a sudden course of the reaction, so that the gelling time (pot life, processability) of the binder system is low and the reaction must be more controlled, for example by separately adding the components. On the other hand, then a less reactive isocyanate group-containing component can be used in combination with ammonia.

The combined addition, z. As ammonium carbonate and ammonium bicarbonate, the gel time, d. H. the usability of the binder mixture down. To avoid this, 2-component systems can be used. In the case of particleboard, fibreboard and OSB, the isocyanate (eg PMDI) and the ammonium salt solution can be applied to the wood components through separate nozzles.

The use of both ammonium carbonates, or ammonium carbamate with one or both ammonium carbonates, can lead to high foaming of the adhesive formulation. This is due to the release of CO ₂ upon decomposition of the ammonium carbonates. On the other hand, the reaction of the isocyanate with released ammonia results in a lower production of CO ₂ by decarboxylation of the isocyanate. A strong CO ₂ evolution may be detrimental to use as a binder for wood-based materials be, because so the gas pressure in the press increase and it can come when releasing the press to splitters. On the other hand, foaming the binder formulation may also be advantageous because it allows the production of foamed, lighter wood materials.

The acceleration of polyurea formation / biuret polymer formation by ammonium compounds, especially by carbonate and bicarbonate or carbamate, or ammonia has not been described. So far, only the acceleration by di- and polyalcohols, tertiary amines (eg., Triethanolamine, triethylamine, N, N-dimethylcyclohexylamine) or metal catalysts, eg. As organic tin, lead, cobalt and mercury compounds known.

Thus, the use of ammonium salts as a reaction accelerator not only makes it possible to produce binder systems based on lignin or tannin, but also, due to the release of carbon dioxide, polyurea foams with biuret groups of di- and polyisocyanates and polyphenols (lignin, tannin) to produce.

Another advantage is that material is lost by the addition of water and decarboxylation of CO ₂ from the isocyanate group-containing components. By reaction of NH ₃ with the isocyanate group, the CO ₂ elimination is prevented and at the same time cheap NH _{3 incorporated} into the polyurea chain.

One embodiment of the invention therefore relates to a process for producing wood-based materials, in particular comprising the steps of contacting lignocellulose-containing material with a binder system and curing the binder, the lignocellulose-containing material and the binder system as defined in the claims is.

Description of the figures and chemical formulas

The chemical structure of polymeric diphenylmethane diisocyanate (PMDI) is shown below:

The polyaddition of diisocyanate and diamine to form pure polyurea without biuret group (not according to the invention) is shown below:

The addition of water to isocyanate and formation of an amino group is shown below: RN = C = O + H ₂ O. RN (H) -COOH. RNH ₂ + CO ₂

The acidity of the ammonium is shown below: NH ₄ ⁺ <==> NH ₃ + H ⁺

The addition of ammonia to isocyanate to form a urea derivative is shown below: RN = C = O + NH ₃ .R-NH-C (= O) -NH ₂

The addition of the isocyanate to the urea derivative is shown below: R-NH-C (= O) -NH ₂ + R'-N = C = O * R-NH-C (= O) -NH-C (= O) -NH-R '

1 : Amount of heat produced over a temperature range of 20-150 ° C measured in a Differential Scanning Calorimeter (DSC).

2 : Amount of heat produced by a system of PMDI and water (reference) and PMDI to which ammonium carbonate was added in three concentrations as measured by DSC.

3 : Amount of heat produced by a system of PMDI and water (Reference) and PMDI to which ammonium bicarbonate was added in three concentrations as measured by DSC.

4 Tensile shear strengths [N / mm ² ] of glued beech veneers with PMDI and water (10%, W / W) at 80 ° C and 120 ° C; and the press times 20, 40, 120 and 200 s.

5 Tensile shear strengths [N / mm ² ] of PMDI with ammonium bicarbonate (20, 10, 5%, W / W) at 80 ° C and 20 s pressing time.

6 Tensile shear strengths [N / mm ² ] of PMDI with ammonium carbonate (20, 10, 5%, W / W) at 80 ° C. and 20 s pressing time (30 s pressing time at "AC 5%, 30 s").

Detailed description of the invention

• (i) Bereitstellen von Lignocellulose-enthaltendem Material, enthaltend 5–40 Gew.-% Lignine und 15–95 Gew.-% Holocellulose;
• (ii) In-Kontakt-Bringen des Materials aus Schritt (i) mit einem Bindemittelsystem, umfassend mindestens die folgenden Komponenten: (a) mindestens eine Isocyanatgruppen-enthaltende Komponente (Komponente (a)), (b) mindestens eine Komponente (Komponente (b)), die nicht in situ aus der mindestens einen Isocyanatgruppen-enthaltenden Komponente erzeugt wird, und ausgewählt ist aus der Gruppe bestehend aus Ammoniak; Verbindungen mit einer einzigen primären Aminogruppe; NH₄ ⁺-Salzen; und primären Ammoniumsalzen, wobei die primären Ammoniumsalze keine Ammoniumsalze der dithionigen Säure sind, wobei die Verbindungen mit einer einzigen primären Aminogruppe bevorzugt keine zusätzliche sekundäre oder tertiäre Aminogruppe aufweisen, (c) optional Lignine und/oder Tannine (Komponente (c)), und (d) optional Lösungsmittel (Komponente (d)); wobei das Bindemittelsystem die mindestens eine Isocyanatgruppen-enthaltenden Komponente in einer Menge von mindestens 50 Gew.-%, bezogen auf alle polymerisierbaren Komponenten des Bindemittelsystems, enthält; wobei nur das Lignocellulose-enthaltende Material und optional Lignine und/oder Tannine als Hydroxygruppe-enthaltende Komponente(n) in dem Verfahren verwendet werden, unter Erhalt einer Mischung; und
• (iii) Thermisches, thermomechanisches oder mechanisches Aushärten der Mischung aus Schritt (ii), unter Erhalt eines Holzwerkstoffs.

The present invention relates to a process for the production of wood-based materials, comprising the steps, preferably consisting of the steps:

• (i) providing lignocellulosic material containing 5-40% by weight of lignins and 15-95% by weight of holocellulose;
• (ii) contacting the material of step (i) with a binder system comprising at least the following components: (a) at least one isocyanate group-containing component (component (a)), (b) at least one component (component ( b)) which is not generated in situ from the at least one isocyanate group-containing component and is selected from the group consisting of ammonia; Compounds having a single primary amino group; NH ₄ ⁺ salts; and primary ammonium salts, wherein the primary ammonium salts are not ammonium salts of the dithionic acid, the compounds having a single primary amino group preferably having no additional secondary or tertiary amino group, (c) optionally lignins and / or tannins (component (c)), and ( d) optionally solvent (component (d)); wherein the binder system contains the at least one isocyanate group-containing component in an amount of at least 50% by weight, based on all polymerizable components of the binder system; wherein only the lignocellulosic material and optionally lignins and / or tannins are used as the hydroxy group-containing component (s) in the process to obtain a mixture; and
• (iii) thermally, thermomechanically or mechanically curing the mixture of step (ii) to obtain a woody material.

The process according to the invention comprises the steps (i) - (iii). It does not involve additional steps of adding additional components in addition to the binder system of step (ii). For example, a step can not be inserted between steps (i) and (ii) in which the lignocellulose-containing material is mixed with other components. Thus, in step (iii) only the lignocellulose-containing material is cured with the binder system.

The lignocellulose-containing material may be provided as in known methods and contacted with the binder system. This is usually done at ambient temperature.

The lignocellulose-containing material contains 5-40% by weight of lignins and 15-95% by weight of holocellulose. The holocellulose content is based on the total weight of the lignocellulosic material. The minimum content of holocellulose is preferably higher than 15%, z. B. 20 wt .-% or 25 wt .-%. Prefers the holocellulose content is 30-95% by weight, 40-95% by weight, or preferably 60-95% by weight, or 80-95% by weight.

The lignin content of the lignocellulosic material is 5-40% by weight based on the total weight of the lignocellulosic material. The minimum content of lignin is preferably higher than 5 wt .-%, z. 15-60 wt%, or 20-50 wt%, or 20-40 wt%. In general, the stability of the lignocellulose-containing material and thus of the wood-based material increases with the lignin content. Depending on the application of the wood-based material, it may therefore be desirable to choose a lignocellulose-containing material with a higher lignin content, or to add lignins / tannins as a binder component.

The determination of the holocellulose content is preferably carried out by means of the method described in Wise LE, Murphy, M., D'Addies AA (1946) "Chlorite holocellulose, its fractionation on bearing on summicum wood analysis and on studies on hemicellulose" (Paper Trade Journal 122/29: 11-19) , Here, the holocellulose is obtained by the lignin component of lignocellulose is removed by addition of sodium chlorite and acetic acid oxidatively in aqueous solution, the residue is filtered off, dried and weighed.

• • Das Wasserbad wird auf 80°C eingestellt. Während der Aufwärmehase werden je 2 g des extraktfreien Holzes, d. h. des Zellwandmaterials nach Extraktion mit polaren und unpolaren Lösungsmitteln, in 250 ml Erlenmeyerkolben eingewogen, 80 ml demineralisiertes Wasser zugeben und verrührt.
• • Zu dieser Suspension werden 0.25 ml Essigsäure und 0.75 g Natriumchlorit gegeben. Anschließend werden die Kolben für 1 h in das 80°C Wasserbad gegeben.
• • Diese Abfolge muss 4 × (3 Wiederholungen) erfolgen.
• • Anschließend werden die Suspensionen in Eiswasser gekühlt und abfiltriert. Der Filterrückstand wird mit 100 ml Eiswasser und mit 25 ml Aceton gewaschen.
• • Der Rückstand wird bei 103°C im Trockenschrank getrocknet.

Important parameters of the measurement procedure are briefly described below:

• • The water bath is set to 80 ° C. During the heating phase, 2 g of the extract-free wood, ie the cell wall material after extraction with polar and non-polar solvents, weighed into 250 ml Erlenmeyer flasks, add 80 ml of demineralized water and stirred.
• 0.25 ml of acetic acid and 0.75 g of sodium chlorite are added to this suspension. The flasks are then placed in the 80 ° C water bath for 1 h.
• • This sequence must be done 4 times (3 repetitions).
• • The suspensions are then cooled in iced water and filtered off. The filter residue is washed with 100 ml of ice water and with 25 ml of acetone.
• • The residue is dried at 103 ° C in a drying oven.

In one embodiment, the lignocellulosic material is wood, especially untreated wood derived from nature, especially wood chips, or wood fibers. In the context of the present invention, the term "wood" is understood as follows: Wood refers to the hard tissue of the shoot axes (trunk, branches and twigs) of trees and shrubs. Characteristic here is the incorporation of lignin into the cell wall. In a broader definition wood is therefore also understood as lignified (woody) plant tissue.

In another embodiment, the material is recycled wood containing already cured binder. This already cured binder behaves essentially passively in the process according to the invention. The recycled wood used herein contains a maximum of 20% by weight of cured binder and no uncured binder. In one embodiment, untreated wood or recycled wood is used, with no further chemicals being added to the lignocellulose-containing material in step (i). This means that the untreated wood or recycled wood is merely brought to the desired size / shape and in step (ii) is added to the binder system.

In step (i) of the process, one or more additives may be blended into the lignocellulosic material prior to being brought into contact with the binder system. For example, fillers, in particular light polymer beads, popcorn, expanded clay, expandable graphite, vermiculite, montmorillonite and other (light) minerals can be introduced.

The lignin content is obtained by hydrolysis of the lignocellulose-containing material by boiling with 72% sulfuric acid. The lignin remains insoluble in water, is filtered, dried and weighed. Preferably, the lignin content according to T 222 om-98 ( Reaffirmed standard, 1998, TAPPI ) carried out.

Preferred lignocellulosic materials having the required amount of lignins and cellulose are softwood; Hardwood, preferably birch, beech; Wheat straw; Corn cobs; Bagasse, hemp shives, large grasses like miscanthus; prefers softwood, such as spruce, pine, fir and Douglas fir; Birch wood; and beech wood.

In one embodiment, the lignocellulose-containing material has a formaldehyde emission of at most 6 mg / m ² h as measured by the gas analysis method EN 717-2 over 4 hours at a temperature of 60 ° C on a specimen with the dimensions 400 mm × 50 mm, on. More preferably, the Formaldehyde emission at most 3.5 mg / m ² h or at most 2 mg / m ² h, more preferably at most 1 mg / m ² h, or at most 0.5 mg / m ² h, more preferably at most 0.2 mg / m ² h or 0.1 mg / m ² h, on. In general, from a health point of view, it is desirable that the formaldehyde emission be minimized when the wood material is intended for use in confined spaces. Untreated wood has a formaldehyde emission of at most 1 mg / m ² h. It is therefore defined in the context of the present invention that "untreated wood" meets the condition "at most 1 mg / m ² h of formaldehyde emission".

To determine the formaldehyde emission, the method is preferred EN 717-2 used. This is measured at 60 ° C for four hours and the formaldehyde emission in mg / m ² h and refers to the unsealed total surface of the specimens (400 mm × 50 mm). When small chips are used, specimens of the same size are first produced (with regard to the measuring method, see: Wood-based panels - Determination of formaldehyde release - Part 2: Formaldehyde release by the gas analysis method; EN 717-2: 1994 ).

The formaldehyde content (in contrast to emission) is determined by the perforator method ( EN 120: 1992 ).

In step (ii) of the process, the components (a), (b), optionally (c) and optionally (d), and further, preferably liquid or binder system-soluble, components / additives are used. The entirety of these components is referred to as a "binder system".

According to the invention it is possible to apply the components of the binder system together or separately. The "further components" are preferably used as a mixture with at least one of the components (a) - (d). "Other components" are not necessary but may be included. In one embodiment, no other components are used. In one embodiment, no sulfur-containing components are used in the binder system or no sulfur-containing components are brought into contact with the lignocellulose-containing material, i. H. not added thereto in step (i).

Apart from lignin and tannin, no components with one or more hydroxy group (s) are used according to the invention. In particular, no polyols are added to the untreated wood or the recycled wood. Thus, during the curing step, only aromatic polyurethanes, in particular polyurethanes based on naturally occurring wood in the wood, d. H. Lignins and tannins.

In addition, preference is given to using no components having one or more carboxylic acid groups (n), in particular no aminocarboxylic acids.

Thus, only the components (a) - (d) enumerated in step (ii) are contacted with the lignocellulosic material, i. H. only these components are used as the binder system. More preferably, this binder system is contacted with the lignocellulosic material and no further materials / components are used.

More preferably, according to the present invention, no compound having hydroxy group (s) is used as the component of the binder, i. H. no lignins or tannins are added either. When no lignins or tannins are added, only lignin and tannin already present in the lignocellulosic material are present. In one embodiment, untreated wood is used so that the lignins or tannins are only naturally present. If a recycled wood used contains small amounts of polyols, the use of the wood is not excluded, but according to the invention in any step of the process, a polyol is actively added.

Moreover, it is preferred not to use ammonium dithionite or other reducing compounds as the components in step (ii) (b).

In particular, the process according to the invention preferably does not comprise any step of resin preimpregnation, such as preimpregnation with formaldehyde resins prior to contacting the binder system with the lignocellulose containing material.

In one embodiment, the at least one component (b) may release ammonia under the curing conditions in step (iii). Ammonia-releasing compounds can be prepared by a person skilled in the art be found taking into account the dissociation pressure of the compound and by routine examinations.

The binder system used herein contains a maximum of 20 wt .-% of formaldehyde resin, in particular it is free of formaldehyde resin, such as. B. UF (urea-formaldehyde resin glue), MUF (melamine-urea-formaldehyde glue), MUPF (melamine-urea-phenol-formaldehyde glue) and MF (melamine-formaldehyde condensation resins), or their uncured starting materials, the example in DE19522951 A1 Find application.

After curing of the binder system, the wood material contains the binder. Water contained in the binder system is then almost completely removed.

The binder contains a polyurea derivative with biuret groups / polyurea structural units / biuret polymer formed from at least the isocyanate group-containing component and component (b), and optionally aromatic polyurethane structural units based on wood-naturally occurring polyols or the added lignins and tannins.

After hardening, the wood material preferably contains 30-98% by weight of lignocellulose-containing material and 2-20% by weight of binder, preferably up to 15% by weight of isocyanate. In addition, wood preservatives, flame retardants, emulsifiers, extenders and / or water repellents such as paraffins may be included in the binder system, for example.

Preferably, the proportion of the lignocellulose-containing material and the binder in the cured material from 70 wt .-% to 100 wt .-%, preferably from 80 wt .-% to 100 wt .-%; more preferably from 85% to 100%, even more preferably from 90% to 100%, or 95% to 100%, by weight. For example, the wood material contains only lignocellulose-containing material and binder, and optionally paraffin (e), the binder preferably only from components (a) - (c) or (a) and (b), with some residual water, depending on ambient humidity , z. B. 2-4% residual water after pressing, up to 10% at 50% relative humidity, or up to 30% at high ambient humidity is formed.

• (a) Isocyanatgruppen-enthaltenden Komponente: 50–99 Gew.-%, bevorzugt 55–98 Gew.-% oder 60–98 Gew.-%. Es ist auch möglich, den Gehalt der Isocyanatgruppen-enthaltenen Komponente weiter zu erhöhen: 65–98 Gew.-% oder 70–98 Gew.-%.
• (b) mindestens eine Komponente, die nicht in situ aus der Isocyanatgruppen-enthaltenden Komponente erzeugt wird, und ausgewählt ist aus der Gruppe bestehend aus Ammoniak; Verbindungen mit einer primären Aminogruppe; NH₄ ⁺-Salzen; und primären Ammoniumsalzen: 2–30 Gew.-%.
• (c) optional Lignin und/oder Tannin: 0–30 Gew.-%.
• (d) Lösungsmittel, bevorzugt Wasser: 0–50 Gew.-%, bevorzugt 1–50 Gew.-%. Wasser kann als Lösungsmittel verwendet werden. Wasser wird insbesondere bei der Verwendung von Ammoniumsalzen eingesetzt. Ammoniumsalze können aber auch als Feststoff ohne Wasser eingesetzt werden.

The binder system may contain the following components, based on the total amount of all components of the binder system, for example as follows:

• (a) Isocyanate group-containing component: 50-99% by weight, preferably 55-98% by weight or 60-98% by weight. It is also possible to further increase the content of the isocyanate group-containing component: 65-98% by weight or 70-98% by weight.
• (b) at least one component which is not generated in situ from the isocyanate group-containing component and is selected from the group consisting of ammonia; Compounds having a primary amino group; NH ₄ ⁺ salts; and primary ammonium salts: 2-30% by weight.
• (c) optionally lignin and / or tannin: 0-30% by weight.
• (D) solvent, preferably water: 0-50 wt .-%, preferably 1-50 wt .-%. Water can be used as a solvent. Water is used especially when using ammonium salts. Ammonium salts can also be used as a solid without water.

Other components are preferably used in a total amount of 0-30 wt .-%, based on the binder, preferably 0-20 or 0-10 wt .-%.

Preferably, no further component which can be polymerized with the other components of the binder system is used. In one embodiment, only the specified components (a) - (d), d. H. no additional components used.

The isocyanate group-containing component contains at least two isocyanate groups (NCO groups) and is thus a di- or polyisocyanate component, preferably diphenylmethane diisocyanate.

In one embodiment, diphenylmethane diisocyanate is used as the isocyanate group-containing component in combination with ammonium carbonate, ammonium carbamate and / or ammonium hydrogencarbonate as a component in step (ii) (b).

The wood material produced according to the invention may be selected from the group consisting of fiberboard, chipboard, insulation, insulation boards, Oriented Strandboards, Unoriented Strandboards, veneers, plywood, wood composites and Engineered Wood Products, in particular the Wood-based materials Medium-density wood-based materials with a density of 550 kg / m ³ to 800 kg / m ³ , ultra-light wood materials with a density of less than 550 kg / m ³ or high-density wood materials with a density greater than 800 kg / m ³ .

The term "engineered wood products" (man-made wood) refers to bonded products that can replace solid wood as load-bearing materials, such as chip or fiber materials, or solid wood products such as glulam (with and without finger jointing).

Component (b) is part of the binder system and accelerates the curing of the binder. Component (b) is not generated in situ from the isocyanate group-containing component in the process of the invention, but used as a separate component. Component (b) contains at least two, d. H. two, three or four, under curing conditions to isocyanate-reactive nitrogen hydrogen atoms.

The at least one component (b) which is not generated in situ from the isocyanate group-containing component is selected from the group consisting of ammonia; Compounds having a primary amino group; NH ₄ ⁺ salts; and primary ammonium salts: 0.1-30% by weight. A particularly strong acceleration of the reaction results when component (b) releases ammonia under curing conditions or when ammonia is used directly. The ammonia-releasing component (b) releases ammonia preferably from a temperature of 80 ° C or 60 ° C, more preferably 50 ° C or 45 ° C, or by proton release.

The component (b) preferably contains no hydroxyl group (s). The component (b) according to the invention is part of the cured polyurea derivative.

In one embodiment, the at least one component (b) in step (ii) is selected from ammonia and ammonium compounds, wherein the ammonium compound (s) is / are in particular ammonium hydroxide, ammonium carbamate, ammonium carbonate diammonium hydrogenphosphate, ammonium hydrogensulfate and / or ammonium bicarbonate, in particular ammonium carbonate.

In one embodiment, the at least one component (b) of step (ii) is selected from ammonium carbonate, ammonium carbamate and ammonium bicarbonate, preferably ammonium carbonate, and ammonium bicarbonate, and the cured wood material contains a polyurea foam or polybiuret foam.

In one embodiment of the process, the isocyanate group-containing component and the at least one component (b) of the binder system are sprayed on separately from one another by means of nozzles.

The separate application of the components can prevent too fast hardening of the isocyanate binder or excessive foaming. In this case, the curing rate and the foaming tendency are dependent on the components used. The two components can be applied to wood fibers or chips, for example. For example, an ammonium salt solution may be used as the component in step (ii) (b).

In another embodiment, the binder system is present as a mixture of all components, e.g. For example, the at least one component (b) is used in step (ii) as an additive to the isocyanate binder-water mixture. The isocyanate group-containing component (eg PMDI) and the at least one NH ₂ and / or -NH ₃ group (n) -containing component (eg ammonia water) can be mixed together in step (ii) and referred to as Mixture be applied to chips, fibers or strands. Alternatively, however, both components can also be sprayed on separately or together.

Curing at a binder temperature in a range from 20 ° C. to 140 ° C., preferably from 30 ° C. to 120 ° C. or from 50 ° C. to 90 ° C., more preferably from 60 ° C. to 80 ° C., is particularly preferred. more preferably 65 ° C to 75 ° C, performed. In this case, the binder temperature can be selected lower during curing, the more reactive component (b) is. The hardening is accelerated by ammonia the strongest.

One embodiment therefore relates to the process wherein ammonia is used in step (ii) and the curing is carried out at a temperature of 10 ° C to 80 ° C or wherein in step (ii) an NH ₄ ⁺ salt is used and the curing at a temperature of 30 ° C to 160 ° C, preferably to 140 ° C.

Here, the binder temperature is the temperature in the core of a plate during curing, z. B. when pressing. The plate temperature on the surface or temperature of the press plates (set in the press) is the surface temperature and is always greater than the core temperature.

Alternatively, or in addition to the use of an elevated temperature in step (iii), as described above, the curing may be carried out under pressing pressure.

The applied pressure can be very different. For example, in the production of insulating materials, a very low pressure is used. Medium pressure is used in the production of MDF / medium density fiberboard and high pressure is used in the production of HDF / high density fiberboard. The pressure used can therefore be suitably selected by the skilled person depending on the wood material to be produced.

The invention also relates to the use of a component (b) as defined herein for accelerating the curing of a binder system in a wood-based material, in particular for accelerating the curing step (iii) in the process according to the invention.

• (a) mindestens eine Isocyanatgruppen-enthaltende Komponente,
• (b) mindestens die eine Komponente (b), ausgewählt aus der Gruppe bestehend aus Ammoniak; Verbindungen mit einer primären Aminogruppe; NH₄ ⁺-Salzen; und primären Ammoniumsalzen, wobei die primären Ammoniumsalze keine Ammoniumsalze der dithionigen Säure sind,
• (c) optional Lignine und/oder Tannine, und
• (d) optional Lösungsmittel; wobei das Bindemittelsystem die mindestens eine Isocyanatgruppen-enthaltenden Komponente in einer Menge von mindestens 50 Gew.-%, bezogen auf alle polymerisierbaren Komponenten des Bindemittelsystems, enthält; wobei nur Lignine und/oder Tannine als Hydroxygruppe-enthaltende Komponente(n) in dem Bindemittelsystem enthalten sein können.

The invention thus also relates to the use of a component (b), as defined below, for accelerating the curing of a binder system in a wood material, wherein the binder system contains the following components:

• (a) at least one isocyanate group-containing component,
• (b) at least one component (b) selected from the group consisting of ammonia; Compounds having a primary amino group; NH ₄ ⁺ salts; and primary ammonium salts, wherein the primary ammonium salts are not ammonium salts of the dithionic acid,
• (c) optionally lignins and / or tannins, and
• (d) optionally, solvent; wherein the binder system contains the at least one isocyanate group-containing component in an amount of at least 50% by weight, based on all polymerizable components of the binder system; wherein only lignins and / or tannins as hydroxy group-containing component (s) may be contained in the binder system.

In addition, the invention relates to a wood-based material produced or producible by a method as described herein. The wood-based material has biuret compounds in the binder.

The detection of reaction products of the reaction of the OH groups of lignin / tannin and isocyanate is preferably carried out by NMR spectroscopy.

The present invention also relates to the use of a component selected from the group consisting of ammonia; Compounds with a primary amine group; NH ₄ ⁺ salts; and primary ammonium salts in the process of the invention, in particular for accelerating the curing of an isocyanate component in a lignocellulose-containing material, in the absence of additional hydroxy group (n) -containing or amino group-containing components.

The present invention also relates to products which can be prepared by the process according to the invention or have been produced therewith.

In particular, the present invention relates to wood-based materials which, after curing, contain a binder having the structural unit - [NH-C (OO) -NR 1 -C (= O) -NH] - where R 1 may be a hydrogen atom or a corresponding structure. Groups of starting materials, or may be contained in the molecule and initial substitution groups, such as. As phenyl groups in PMDI, etc.

Thus, the binder preferably contains the structural unit - [NH-C (= O) -NR 1 -C (= O) -NRH] - where R 1 is hydrogen (if an ammonia-releasing component is used) or represents the group which is formed by the primary amine used.

Preferably, the structural unit is - [NH-C (= O) -NH-C (= O) -NH] -.

In particular, these wood-based materials preferably contain no UF (urea-formaldehyde resin glue), MUF (melamine-urea-formaldehyde glue), MUPF (melamine-urea-phenol-formaldehyde glue) or MF (melamine-formaldehyde condensation resins), or their uncured starting materials.

If component (b) does not release ammonia under the curing conditions, e.g. B. if primary amines are used with low dissociation pressure, then produced after reaction with isocyanate no urea with NH ₂ group, but with a NHR group. In the case of primary amines having two or more amino groups, first one and then the other amino group reacts with isocyanate, but not twice the same amino group as is required according to the invention.

Thermal Curing: This term refers to the curing or polymerization or the polyaddition of the isocyanate group-containing component with the component from step (ii) (b) of the process at elevated adhesive temperature, without the addition of further catalysts. Preferably, this temperature is greater than 50 ° C and less than 120 ° C.

The term "material" as used herein refers to materials which, after further processing, may be added to the intended use. For example, insulation panels can be cut to size and then installed in the object to be insulated.

The term "derived from nature" means that the lignocellulose-containing material is obtained from plants, whereby the plants can be cultivated, or from natural stocks, e.g. As forests, can come.

The term "unsubstituted ammonium salts" is synonymous with "NH ₄ ⁺ salts".

The term "primary ammonium salts" refers to "RNH ₃ ⁺ salts". Compounds with an amino group can be described as R-NH ₂ . In the R-NH ₃ ⁺ salts and R-NH ₂ compounds, R is preferably selected from linear or branched alkyl groups (preferably C 1-20 alkyl, especially C 1-8 alkyl), heteroalkyl groups (preferably C 1-20 heteroalkyl, especially C 1-4 -8 heteroalkyl), cycloalkyl groups (preferably C1-20 cycloalkyl, especially C1-8 cycloalkyl), heterocycloalkyl groups (preferably C1-20 heterocycloalkyl, especially C1-8 heterocycloalkyl), aryl groups, heteroaryl groups, acygroups (preferably C1-20 acyl, especially C1- 8 acyl), aikoxy groups (preferably C1-20), aryloxy groups (preferably C1-12).

Here, the individual groups (alkyl, aryl,...) May optionally be substituted, the term "substituted" referring to these groups having one or more substituents selected from the group comprising OH, = O, = S , = NR ^h , = N-OR ^h , S ^h , NH ₂ , NO ₂ , NO ₂ , N ₃ , CF ₃ , CN, OCN, SCN, NCO, NCS, C (O) NH ₂ , C (O) H, C (O) OH, halo, R ^h , SR ^h , S (O) R ^h , S (O) OR ^h , S (O) ₂ R ^h , S (O) ₂ OR ^h , OS (O) R ^h , OS (O) OR ^h , OS (O) ₂ R ^h , OS (O) ₂ OR ^h , OP (O) (OR ^h ) (OR ⁱ ), P (O) (OR ^h ) (OR ⁱ ), OR ^h , NHR ⁱ , N (R ^h ) R ⁱ , ⁺ N (R ^h ) (R ⁱ ) R ^j , Si (R ^h ) (R ⁱ ) R ^j , Si (R ^h ) (R ⁱ ) R ^j , C (O) R ^h , C (O) OR ^h , C (O) N (R ⁱ ) R ^h , OC (O) R ^h , OC (O) OR ^h , OC (O) N (R ^h ) R ⁱ , N (R ⁱ ) C (O) R ^h , N (R ⁱ ) C (O) OR ^h , N (R ⁱ ) C (O) N (R ^j ) R ^h , and the thio derivatives thereof Substituents, or a protonated or deprotonated form of these substituents, wherein R ^h , R ⁱ , and R ^{j are} independently selected from H and optionally substituted C 1-15 alkyl, C 1-15 He teroalkyl, C3-15 cycloalkyl, C3-15 heterocycloalkyl, C4-15 aryl, or C4-15 heteroaryl or a combination thereof, two or more of R ^h , R ⁱ , and R ^j are optionally joined together to form one or more carbon cycles or form heterocycles.

The term "alkyl" as used herein refers to straight-chained or branched, saturated or unsaturated hydrocarbon substituents, examples of the alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, isopropyl, sec Butyl, isobutyl, tert-butyl, isopentyl, vinyl, allyl, 1-butenyl, 2-butenyl, isobutenyl, and pentenyl.

The term "cycloalkyl" or "carbon cycles" as used herein refers to saturated or unsaturated, non-aromatic hydrocarbon cycles which may consist of one, two or more rings. Examples thereof include cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclopentadienyl, cyclohexyl, cyclohexonyl, etc.

The term "heteroalkyl" as used herein refers to straight-chain or branched, saturated or unsaturated hydrocarbon substituents in which at least one carbon is replaced by a heteroatom. The heteroatoms are preferably selected from S, N, O, and P.

The term "aryl" as used herein refers to aromatic substituents which may be one or more rings fused together. Examples of aryl include phenyl, naphthyl and antracenyl.

The term "acyl" as used herein refers to the functional group having the general structure Ra- (C = O) - wherein Ra represents an optionally substituted hydrocarbon radical, especially a carbon chain having C1 to C8 carbon atoms.

The term "heteroaryl" as used herein refers to aromatic substituents which may consist of one or more rings fused together. Here, at least one carbon atom of the aromatic R group is replaced by a heteroatom, in particular S, N, O or P. Examples of heteroaryl groups include: pyridinyl, furanyl, pyrrolyl, triazolyl, pyrazolyl, imidazolyl, thiophenyl, indolyl, benzofuranyl, benzimidazolyl, indazolyl , Benzotriazolyl, benzisoxazolyl, and quinolinyl.

The term "heterocycloalkyl" or "heterocycles" as used herein refers to saturated or unsaturated, non-aromatic cyclic hydrocarbon substituents which may consist of one or more fused rings, with at least one carbon in one of the rings substituted by a heteroatom, especially S, N, O or P. Examples of heterocycloalkyl include tetrahydrofuranyl, pyrrolidinyl, piperidinyl, 1,4-dioxanyl, morpholinyl, piperazinyl, oxyzolidinyl, decahydroquinolinyl.

When terms such as "optionally substituted" are used, these terms refer to all subsequent residues unless otherwise specified.

That is, the term "optionally substituted alkyl, heteroalkyl, aryl, acyl" is to be read as "optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted acyl".

The production of the wood materials can be carried out using conventional devices, for. B. heating presses, as known in the art, done. Exemplary methods can be found in the documents cited herein, for example, in U.S. Pat DE2711958 , See also Dunky, M., Niemz, P. (2002) Wood materials and glues - technology and influencing factors. Springer-Verlag, Berlin, Heidelberg, pages 122-128 ; and Deppe, H., Ernst, K. (2000) Taschenbuch der Spanplattentechnik. DRW publishing house, Leinfelden-Echterdingen ,

The terms "thermal curing," "thermo-mechanical curing," or "mechanical curing" of the mixture refers to the use of process conditions that allow the binder system of the present invention to be polymerized. Suitable conditions are known to those skilled in the art and can be optimized by routine experimentation depending on the binder system.

Examples

In the context of the present invention, the curing behavior isocyanate group-containing component was investigated using the example of the PMDI, especially in differential scanning calorimeter (DSC). As a result, the direct addition of ammonia to the reaction mixture resulted in a significant decrease in the temperature at which the exothermic reaction started (onset temperature, 1 ). However, the reaction was so violent that not all the heat energy could be measured. In contrast, the addition of ammonium sulfate gave only a slight decrease in the onset temperature ( 1 ).

A much better controlled acceleration of the reaction was evident when using ammonium carbonate and bicarbonate. Ammonium carbonate decomposes at 58 ° C, ammonium bicarbonate at about 60 ° C completely in ammonia, carbon dioxide and water. The released during thermal decomposition ammonia gas leads to an accelerated curing of PMDI ( 2 and 3 ).

The manifestation of the strengths over various temperatures and concentrations of the accelerators ammonium carbonate and ammonium hydrogencarbonate was determined with the aid of the ABES (Automated Bonding Evaluation System). Here, veneers are glued together and the tensile shear strength determined. As a reference (Ref), first a series of measurements with pure PMDI and 10% water addition (W / W) and different temperatures and pressing times was created ( 4 ).

Only from a temperature of 120 ° C and 120 s pressing time, an actual bonding of the joint could be measured, the other variants with lower temperatures or pressing times formed no strength. The displayed strength values correspond to the blank value of the ABES, or those of non-glued veneers. The addition of ammonium bicarbonate (AHC) in concentrations of 5, 10, 20% (mass AHC / mass PMDI) has already enabled the measurement of tensile shear strengths at a temperature of 80 ° C and 20 s, which correspond to the reference measurements of 120 ° C and 120 s correspond ( 5 ). The variant with 5% addition showed the lowest strengths.

The strengths could be further improved by the addition of ammonium carbonate (AC), which is probably due to the higher proportion of ammonium with the same amount of salt ( 6 ).

The strengths of the variants 20% and 10% at 80 ° C and 20 s pressing time correspond to the reference values at 120 ° C and 200 s. Also at AC, a strength drop of the variant could be measured at 5%, which, however, was no longer observed when the pressing time was increased by 10 s ("AC 5%, 30 s").

Quoted literature:

• DE10356767 A1 ;
• DE19522951 A1 ;
• DE2711958 A1 ;
• DE10 2007 038 085 A1
• DE19959170 A1 ;
• DE19812751 A1 ;
• Dunky, M., Niemz, R (2002) Wood materials and glues - technology and influencing factors. Springer-Verlag, Berlin, Heidelberg, pages 122-128 and 386-391 ;
• Deppe, H., Ernst, K. (2000) Taschenbuch der Spanplattentechnik. DRW publishing house, Leinfelden-Echterdingen EP 2062708A2 ;
• EP2193899A1 ;
• EP2644340A1 ;
• Wise LE, Murphy, M., D'Addies AA (1946) "Chlorite holocellulose, its fractionation on bearing on summicum wood analysis and on studies on hemicellulose" (Paper Trade Journal 122/29: 11-19) ,

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19522951 A1 [0011, 0072]
• DE 10356767 A1 [0012, 0013]
• DE 2711958 A1 [0013, 0013]
• EP 2062708 A2 [0014, 0016]
• EP 2193899 A1 [0016, 0016]
• EP 2644340 A1 [0016, 0016]
• DE 102007038085 A1 [0017]
• DE 19959170 A1 [0018, 0018]
• DE 19812751 A1 [0019, 0019]
• DE 2711958 [0123]

Cited non-patent literature

• EN 312-5 and 7, respectively [0003]
• Dunky and Niemz 2002 [0024]
• Wise LE, Murphy, M., D'Addies AA (1946) "Chlorite holocellulose, its fractionation on summative wood analysis and on hemicellulose" (Paper Trade Journal 122/29: 11-19) [0053]
• Reaffirmed standard, 1998, TAPPI [0058]
• EN 717-2 [0060]
• EN 717-2 [0061]
• EN 717-2: 1994 [0061]
• EN 120: 1992 [0062]
• Dunky, M., Niemz, P. (2002) Wood materials and glues - technology and influencing factors. Springer-Verlag, Berlin, Heidelberg, pages 122-128 [0123]
• Deppe, H., Ernst, K. (2000) Taschenbuch der Spanplattentechnik. DRW-Verlag, Leinfelden-Echterdingen [0123]

Claims (11)

A process for producing wood-base materials comprising the steps, preferably comprising the steps of: (i) providing lignocellulose-containing material containing 5-40% by weight of lignins and 15-95% by weight of holocellulose; (ii) contacting the material of step (i) with a binder system comprising at least the following components: (a) at least one isocyanate group-containing component, (b) at least one component not in situ from the at least one Isocyanate group-containing component is produced, and is selected from the group consisting of ammonia; Compounds having a single primary amino group; NH ₄ ⁺ salts; and primary ammonium salts, wherein the primary ammonium salts are not ammonium salts of the dithionic acid, (c) optionally lignins and / or tannins, and (d) optionally, solvents; wherein the binder system contains the at least one isocyanate group-containing component in an amount of at least 50% by weight, based on all polymerizable components of the binder system; wherein only the lignocellulosic material and optionally lignins and / or tannins are used as the hydroxy group-containing component (s) in the process to obtain a mixture; and (iii) thermally, thermomechanically or mechanically curing the mixture of step (ii) to obtain a woody material. The process of claim 1, wherein the at least one component (b) releases ammonia under the curing conditions in step (iii). The process according to claim 1 or 2, wherein the binder system contains the following components, based on the total amount of all components of the binder system: (a) isocyanate group-containing component: 50-98% by weight; (b) at least one component which is not generated in situ from the isocyanate group-containing component and is selected from the group consisting of ammonia; Compounds having a primary amino group; NH ₄ ⁺ salts; and primary ammonium salts: 2-30% by weight; (c) optionally lignin and / or tannin: 0-30% by weight; and (d) solvent, preferably water: 0-50 wt%, preferably 1-50 wt%. The process according to any one of the preceding claims, wherein the isocyanate group-containing component is a di- or polyisocyanate component, preferably diphenylmethane diisocyanate. The method according to one of the preceding claims, wherein the wood material is selected from the group consisting of fiberboard, chipboard, insulation, insulation boards, Oriented Strandboards, Unoriented Strandboards, veneers, plywood, wood composites and engineered wood products, in particular the wood materials are medium-density wood materials with a Density from 550 kg / m ³ to 800 kg / m ³ , ultra light wood materials with a density of less than 550 kg / m ³ and high density wood materials with a density greater than 800 kg / m ³ . The method according to any of the preceding claims, wherein the at least one component (b) in step (ii) is selected from ammonia and ammonium compounds, wherein the ammonium compounds are preferably ammonium carbonate, ammonium carbamate, diammonium hydrogenphosphate, ammonium hydrogensulfate and / or ammonium hydrogencarbonate. The process according to any of the preceding claims, wherein the isocyanate group-containing component and the at least one component (b) of the binder system are sprayed separately by means of nozzles. The process according to any of the preceding claims, wherein the at least one component (b) of step (ii) is selected from ammonium carbonate, ammonium carbamate and ammonium bicarbonate and the cured wood material contains a polyurea foam or polybiuret foam. The process according to any one of the preceding claims, wherein in step (i) one or more additives are mixed into the lignocellulosic material before it is brought into contact with the binder system. Use of a component (b), as defined below, for accelerating the curing of a binder system in a wood material, wherein the binder system contains the following components: (a) at least one isocyanate group-containing component, (b) at least one component (b), selected from the group consisting of ammonia; Compounds having a primary amino group; NH ₄ ⁺ salts; and primary ammonium salts, wherein the primary ammonium salts are not ammonium salts of the dithionic acid, (c) optionally lignins and / or tannins, and (d) optionally, solvents; wherein the binder system contains the at least one isocyanate group-containing component in an amount of at least 50% by weight, based on all polymerizable components of the binder system; wherein only lignins and / or tannins as hydroxy group-containing component (s) may be contained in the binder system. Wood material, produced or producible by a method according to any one of claims 1-9.

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