Process for producing a woodbase material board provided with a flame retardant

Abstract

The present invention relates to a process for producing a woodbase material board provided with a flame retardant, wherein at least one flame retardant is applied to the wood particles in the form of a suspension during the production process, wherein the flame retardant suspension comprises: at least one phosphate salt and / or sulfate, a mixture of at least one compound of the general formula (I) R1 aSiX(4-a) where X is alkoxy, and R1 is an organic radical selected from the group comprising alkyl, cycloalkyl and phenyl, and a = 1, 2, 3, especially 1 or 2, at least one compound of the general formula (II) SiX4 where X is alkoxy, and at least one compound of the general formula (III) R2SiX3 where X is alkoxy, and R2 is an organic radical selected from the group comprising C1-C10 alkyl which may be interrupted by -O- or -NH-, and where R2 has at least one functional group Q1 selected from a group containing a methacryloyl, methacryloyloxy, vinyl and epoxy group.

Description

[0001] Process for producing a wood-based panel provided with a flame retardant

[0002] The present invention relates to a process for producing a wood-based panel provided with a flame retardant and wood-based panels containing this flame retardant.

[0003] Description

[0004] In recent years, there have been repeated serious fires in buildings, sometimes resulting in significant casualties. This has led to stricter legal regulations regarding fire protection. At the same time, however, certain flame retardants have been banned or their use strictly regulated due to environmental or health concerns (such as boron salts). In addition to the resulting stricter requirements regarding the flammability / combustibility of products in certain applications, there is also a demand for flame-retardant products in many applications where fire protection is not relevant. This also applies to wood-based materials, which are used either in the structural sector for walls, floors, or ceilings (prefabricated housing) or in the decorative sector for laminate flooring, furniture, panels, etc.OSB (Oriented Strand Board), plywood and chipboard are used in the structural sector and MDF / HDF (Medium Density Fiberboard / High Density Fiberboard) and chipboard are used in the decorative sector.

[0005] Inorganic salts are typically used in the production of flame-resistant wood materials. These are almost exclusively sulfates, phosphates, and / or polyphosphates as ammonium salts. This is because these salts deliver particularly good results in terms of flame resistance. These salts must be used in solutions with relatively high concentrations; otherwise, the water contained in the salt suspensions used would cause additional problems, requiring the water to be removed from the process.

[0006] While it is relatively easy to incorporate the flame retardant (FR) into the wood matrix during the production of flame-retardant particleboard or fiberboard, adding it to OSB strands presents problems. Strands are the coarse particles used in the production of OSB. These OSBs, originally a waste product from the veneer and plywood industries, are increasingly being used in timber and prefabricated house construction because they are lightweight yet meet the structural requirements of building boards. OSBs are used as building boards, as wall and roof paneling, and even in flooring.

[0007] OSB is manufactured in a multi-stage process. First, the chips or strands of debarked roundwood, preferably softwood, are peeled lengthwise by rotating knives. In the subsequent drying process, the natural moisture content of the strands is reduced at high temperatures. The moisture content of the strands can vary depending on the adhesive used, but it should be well below 10% to avoid cracking due to excessive vapor pressure in the board during subsequent pressing. Depending on the adhesive, wetting may be more effective on relatively moist strands or on dry strands.

[0008] After the strands have dried, they are fed into a gluing device, where the glue or adhesive is finely distributed onto the chips. PMDI (polymeric diphenylmethane diisocyanate) or MUPF (melamine urea phenol formaldehyde) glues are predominantly used for gluing. These glues can also be mixed in OSB. These glues are used because, as mentioned above, OSB is often used for structural applications. In these applications, moisture-resistant glues are required.

[0009] After gluing, the glued strands are spread in spreading devices alternately lengthwise and crosswise to the production direction, so that the strands are arranged crosswise in at least three layers (lower cover layer - middle layer - upper cover layer). The spreading direction of the lower and upper cover layers is the same, but differs from the spreading direction of the middle layer. The strands used in the cover layer and middle layer also differ from one another. For example, the strands used in the cover layers are flat, while those used in the middle layer are less flat and even chip-shaped. Typically, two material strands are used in the production of OSB: one with flat strands for the later cover layers and one with "chips" for the middle layer. Accordingly, the strands in the middle layer can be of lower quality, since the flexural strength is essentially generated by the cover layers.This is why fines created during machining can also be used in the middle layer of OSB boards. After the strands have been scattered, they are continuously compressed under high pressure and at high temperatures of, for example, 200 to 250°C. The OSB strands used in production have a surface that makes it difficult for the aqueous solution of the flame retardant to penetrate. This means that after the water evaporates, the flame retardant is essentially in the form of a powder, unbound, on the strands. Because the strands rub against each other until they are scattered by the conveyor device, some of the flame retardant is rubbed off the strands. The flame retardant is subsequently lost during the process or finds itself in areas of the OSB where it plays no role in flammability. This means that the dosage must be increased, which incurs additional costs.This is noticeable, for example, in the fact that the flame retardant is only added to the top layer, but later also appears in the middle layer of the product. Furthermore, the increased amount of flame retardant must be compensated for with more glue, as the flame retardant interferes with the bonding process.

[0010] Furthermore, the production of flame-retardant wood-based panels in general, and OSB in particular, is very complex, as approximately 20% by weight of flame retardant must be added to the wood in the panel. It must be taken into account that significant quantities of product must be discarded at the beginning and end of production because the required amount of flame retardant is not yet present or no longer present in the strands. This also leads to increased costs and makes the process inflexible, as the largest possible quantities of flame-retardant panels must always be produced to minimize losses relative to the production volume.

[0011] Furthermore, flame retardant solutions typically contain approximately 50% by weight of flame retardant. Higher concentrations are only possible by heating the solutions, which is technically impossible in many systems. This also limits the dosage due to the amount of water introduced into the system, as excessive water leads to excessive vapor pressure in the board, thus causing cracking. This, of course, also means that the highly concentrated flame retardant is less well distributed across the strands than with a less concentrated solution.

[0012] Another problem is that steam injection systems are now installed upstream of continuous presses to increase production speed. This superheated steam ensures that the strand cake is preheated, thus more quickly reaching the temperature required for curing the glue used, such as PMDI glue. This steam, which is applied to the strands at high pressure, naturally also washes away some of the flame retardant from the strands.

[0013] This results in disadvantages, in particular higher costs, greater loss and an inflexible process.

[0014] The invention is therefore based on the technical task of solving the problems described above. This should be achieved, if possible, without significant changes to the process. The solution should also not create any other problems, e.g., through the addition of critical ingredients or solvents. Furthermore, any solutions used should be compatible with the flame retardant used.

[0015] This object is achieved according to the invention by a method for producing a wood-based panel provided with a flame retardant having the features of claim 1.

[0016] Accordingly, a method for producing a wood-based panel from wood particles is provided, wherein at least one flame retardant in the form of a suspension, in particular an aqueous suspension, is applied to the wood particles during the production process, wherein the flame retardant suspension comprises the following components:

[0017] - at least one phosphate salt and / or sulfate, and a mixture of at least one compound of general formula (I)

[0018] R 1 aSiX(4-a) (I), where

[0019] - X is alkoxy, and

[0020] - R 1 an organic radical is selected from the group comprising alkyl, cycloalkyl or phenyl, and

[0021] - a = 1, 2, 3, in particular 1 or 2,

[0022] - at least one compound of the general formula (II) SiX4(II), where X is alkoxy, and

[0023] - at least one compound of the general formula (III)

[0024] R 2 SiX3(III), where

[0025] - X is alkoxy, and

[0026] - R 2 an organic radical is selected from the group comprising C1 -C10 alkyl, which may be interrupted by -O- or -NH-, and

[0027] - where R 2has at least one functional group Qi selected from a group containing a methacrylic, methacryloxy, vinyl, and epoxy group,

[0028] - b = 1, 2, 3, in particular 1 or 2.

[0029] Accordingly, a composition of at least one phosphate and a silane mixture is provided for use in wood-based panels, wherein the silanes or silane mixture used act as a fixative for the phosphate or sulfate on the wood particles used for the wood-based panels; i.e. a fixative for the flame retardant on the wood particles is introduced with the silanes. The aim is to prevent or reduce the abrasion / falling off of the flame retardant after application to the wood particles, such as strands or chips, until the wood particles are compressed to form wood-based panels. For this purpose, the silane mixture of three different silanes is added to the flame retardant before it is dosed onto the wood particles. This can take place in the storage tank or before the flame retardant is applied to the wood particles.

[0030] The silanes react with the flame retardant on the one hand and with the surface of the wood particles on the other. Due to their reactivity with the wood surface, the silane compounds improve the adhesion of the phosphate to the wood surface of the wood particles. The silane compound of formula (I) binds to the flame retardant via the organic radical. The silane compound of formula (II) serves to build up an SiO2 network via condensation of the OH groups. The alkyl groups, such as methyl, of the silane compound of formula (I) cause a "loosening" of the three-dimensional SiO2 network, which forms through condensation. More flexible network structures are built up that are not too brittle. The silane compound of formula (III) has at least one functional group, such as isocyanate or glycidyl groups, for chemical bonding to free OH groups of the cellulose on the wood particle surface.

[0031] The use of this composition as a flame retardant offers several advantages. For example, more precise dosing of the flame retardant is possible, thus reducing the required amount of flame retardant, which can reduce the cost of the flame retardant, and also enables better material utilization.

[0032] The (hydrolyzable) radical X of the silane compounds of the formulas (I)-(III) is advantageously selected from a group containing C 1-6 alkoxy, in particular methoxy, ethoxy, n-propoxy, i-propoxy, and butoxy. Methoxy and ethoxy are particularly preferred.

[0033] The organic residue R 1The compound of general formula (I) is preferably selected from a group comprising C1-C10 alkyl, preferably C1-C8 alkyl, particularly preferably methyl, ethyl, propyl, pentyl, hexyl, heptyl, and octyl. The term "cycloalkyl" encompasses the groups cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl.

[0034] The compound of general formula (I) may in particular comprise one of the following formulas: R 1 SiX3or R 1 2SiX2with R 1 as a C1-C10 alkyl group, preferably methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, and with X as alkoxy, in particular methoxy, ethoxy, n-propoxy or i-propoxy.

[0035] In a variant of the present composition, compounds of the general formula (I) according to R 1 a SiX(4-a), especially R 1 SiX3, selected from methyltriethoxysilane, phenyltriethoxysilane, dimethyldiethoxysilane, octyltriethoxysilane.

[0036] In a particularly preferred variant of the present composition, the compound of general formula (II) SiX4 comprises methoxy, ethoxy, n-propoxy or i-propoxy and butoxy as X. Particularly preferred are the compounds tetramethoxysilane and tetraethoxysilane as compound of general formula (II).

[0037] The organic R 2 The compound of general formula (III) is preferably selected from a group comprising methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, which may be interrupted by -O- or -NH-. In one embodiment of the present composition, the at least one functional group Q 1 the compound of general formula (III) selected from a group containing epoxy, methacryloxy, amino, and vinyl. Particularly preferred functional group Q 1 is glycidyloxy. The functional group Q 1advantageously has a residue with a double bond or an epoxy group which can be activated and polymerized by means of UV radiation.

[0038] The functional groups through which crosslinking with the wood surface of the wood particles is possible include, in particular, polymerizable and / or polycondensable groups, whereby the polymerization reaction also includes polyaddition reactions. The functional groups are preferably selected such that organic crosslinking between the phosphate / sulfate flame retardant and the wood surface can be achieved via optionally catalyzed polymerization and / or condensation reactions.

[0039] In a particularly preferred variant of the present composition, the compound of general formula (III) comprises methoxy, ethoxy, n-propoxy or i-propoxy and butoxy, as X, preferably methoxy and ethoxy.

[0040] Particularly preferred compounds are glycidyoxypropyltriethoxysilane and glycidyoxypropyltrimethyoxysilane as compounds of general formula (III).

[0041] According to one variant, the composition comprises a silane mixture in which a first compound of formula (I) R 1 a SiX( 4.a ) with a= 1, where X is methoxy, ethoxy, n-propoxy or i-propoxy, R 1 Methyl, ethyl, n-propyl or n-butyl, a second compound of the formula (II) SiX4where X is alkoxy, in particular methoxy, ethoxy, n-propoxy or i-propoxy, and a third compound of the formula (III) R 2 bSiX3 with b= 1 , where X is methoxy, ethoxy, n-propoxy or i-propoxy, R is methyl, ethyl, n-propyl or n-butyl and Q is glycidyl or glycidyloxy group.

[0042] Other silanes which do not fall under one of the formulas (l)-(lll) are not part of the composition according to the invention and are therefore excluded.

[0043] In one embodiment of the present composition, the silane mixture comprises 5-25 wt%, preferably 10-20 wt% of at least one silane of formula (I), 3-15 wt%, preferably 6-11 wt% of at least one silane of formula (II) and 5-20 wt%, preferably 8-15 wt% of at least one silane of formula (III).

[0044] In a preferred embodiment, the silane mixture comprises 5-15 wt%, preferably 8-12 wt% of at least one silane of formula (I), 3-10 wt%, preferably 4-7 wt% of at least one silane of formula (II) and 10-20 wt%, preferably 13-17 wt% of at least one silane of formula (III).

[0045] In another preferred embodiment, the silane mixture comprises 15-25 wt%, preferably 18-22 wt% of at least one silane of formula (I), 5-15 wt%, preferably 10-13 wt% of at least one silane of formula (II) and 5-10 wt%, preferably 7-9 wt% of at least one silane of formula (III).

[0046] In a further embodiment of the present composition, the at least one phosphate is a monophosphate or polyphosphate and is used as an ammonium salt or organic salt. Halogen-free phosphates, such as ammonium polyphosphate, are preferred. A mixture of phosphates and sulfates is preferably used.

[0047] In one embodiment, the present composition contains at least one metal alkoxide, in particular a zirconium alkoxide, such as zirconium n-propoxide. The amount of metal alkoxide is preferably 1-3 wt%, in particular 1-2 wt%. The alkoxides used serve as condensation catalysts to achieve the highest possible degree of condensation even at low temperatures.

[0048] In a further embodiment, the present composition contains at least one glycol ether. The glycol ether is added to the composition as a mixture of water and at least one glycol ether, in particular in a mixing ratio of 60 parts water and 40 parts glycol ether. The glycol ethers used are dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, 1-methoxy-2-propanol, tripropylene glycol monobutyl ether, propylene glycol butyl ether, ethylene glycol monophenyl ether, preferably dipropylene glycol monomethyl ether. Glycol ethers serve as a non-flammable solvent that is well suited to both the water of the flame retardant and the alcohol of the silane. When using a glycol ether, the step of using the alcohol formed during the production of the flame retardant can be omitted, as shown below. In a preferred embodiment, the present composition comprises

[0049] - At least one phosphate and / or sulfate,

[0050] - At least one compound of general formula (I) according to R 1 SiX3or R 1 2SiX2with R 1 as a C1-C10 alkyl group, preferably methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, and with X as alkoxy, in particular methoxy, ethoxy, n-propoxy or i-propoxy;

[0051] - At least one compound of general formula (II) according to SiX4with X being methoxy, ethoxy, n-propoxy or i-propoxy and butoxy;

[0052] - At least one compound of the general formula (III) according to R 2 SiX3with R 2 as methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, which may be interrupted by -O- or -NH-, and functionalized with an epoxy or vinyl group as Q1 , and X as methoxy, ethoxy, n-propoxy, i-propoxy or butoxy; and

[0053] - At least one metal alkoxide, preferably zirconium alkoxide,

[0054] - Optionally at least one glycol ether, and

[0055] - Water.

[0056] In a further preferred embodiment, the present composition comprises

[0057] - At least one phosphate and / or sulfate,

[0058] At least one compound of the general formula (I) according to R 1 SiX3or R 1 2SiX2with R 1 as methyl, ethyl, propyl, and with X as methoxy, ethoxy;

[0059] At least one compound of the general formula (II) according to SiX4with X as methoxy, ethoxy;

[0060] At least one compound of the general formula (III) according to R 2 SiX3with R 2 as ethyl, propyl, pentyl, which may be interrupted by -O- or -NH-, and functionalized with an epoxy or vinyl group as Q1 , and X as methoxy, ethoxy; and

[0061] At least one metal alkoxide, preferably zirconium alkoxide, optionally at least one glycol ether, and

[0062] - Water.

[0063] In a further embodiment, the present composition may contain inorganic particles, in particular nanoparticles based on SiO2, such as silica gels or zeolites. The particles preferably used have a size between 2 and 400 nm, preferably between 2 and 100 nm, and particularly preferably between 2 and 50 nm. The addition of the inorganic particles can further increase the amount of active ingredient absorbed.The present flame retardant can be produced in a process comprising the following steps: a) providing an aqueous suspension containing at least one compound of the general formula (I), at least one compound of the general formula (II) and at least one compound of the general formula (III); b) adding at least one catalyst, in particular a basic compound, to the suspension of at least one compound of the formula (I), the formula (II) and the formula (III); c) heating the mixture of at least one compound of the formula (I), the formula (II) and the formula (III) and the at least one catalyst; d) adding at least one metal alkoxide, in particular a zirconium alkoxide, to the mixture, and e1) either separating off the alcoholic phase formed (e.g.by evaporation) of the aqueous phase of the mixture of at least one compound of formula (I), formula (II) and formula (III), or e2) addition of a mixture of water and at least one glycol ether, and f) addition of at least one phosphate and / or sulfate to the mixture obtained in step e1) or step e2).

[0064] Basic compounds such as alkalis such as NaOH, KOH, or ammonium hydroxide solutions are suitable as catalysts. A sodium hydroxide solution, especially a 0.1 molar sodium hydroxide solution, is preferred.

[0065] In one variant, in step f), 20-40 wt%, preferably 25-35 wt%, particularly preferably 30 wt% of the mixture obtained in step e1) or step e2) is added to an aqueous phosphate solution, in particular a phosphate solution with a solids content of 50 wt%. The amount of silane mixture in the final composition is preferably 2-10 wt%, preferably 3-8 wt%, particularly preferably 4-6 wt%, e.g., 5 wt%.

[0066] The resulting aqueous suspension of the flame retardant, consisting of three silanes and phosphate and / or sulfate, is stable and is applied to the wood particles in the form of a spray. The flame retardant is applied during the production of a wood-based panel. Accordingly, a process for producing a wood-based panel is also provided, which comprises the following steps:

[0067] - Providing wood particles, in particular dried wood particles;

[0068] -Gluing the wood particles with a suitable binder,

[0069] - Pressing the glued wood particles to form a wood-based panel, wherein the at least one flame retardant composition described above is applied, in particular sprayed, to the wood particles before, with or after the application of the binder to the wood particles.

[0070] The amount of flame retardant composition sprayed onto the wood particles is between 15 and 30 wt%, preferably between 20 and 25 wt% (solid on wood atro).

[0071] Preferred binders are selected from the group containing formaldehyde adhesives, polyurethane adhesives, epoxy resin adhesives, polyester adhesives, with formaldehyde adhesives being mainly used.

[0072] As formaldehyde adhesive, in particular a phenol-formaldehyde resin adhesive (PF), a cresol / resorcinol-formaldehyde resin adhesive, urea-formaldehyde resin adhesive (UF) and / or melamine-formaldehyde resin adhesive (MF) can be used.

[0073] As an alternative to formaldehyde adhesives, polyurethane adhesives based on aromatic polyisocyanates, in particular polydiphenylmethane diisocyanate (PMDI), toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI), with PMDI being particularly preferred, are available to a lesser extent.

[0074] In addition to the binder, one embodiment also includes adding paraffins (e.g., 3% by weight of a 50% by weight paraffin emulsion) to the wood particles to reduce water absorption and swelling. The paraffin emulsion is preferably sprayed onto the wood particles.

[0075] The manufactured wood-based panels can be a coarse particle board (OSB), a particle board or a plywood board.

[0076] Preferably, OSB boards are produced, the process comprising the following steps: a) producing strands (OSB strands) from suitable wood, b) if necessary, intermediate storage of the wood strands, in particular in silos or bunkers, c) drying the wood strands, d) sorting or sifting the wood strands according to the size of the wood strands, e) gluing the wood strands with a suitable binder, in particular with at least one isocyanate; f) applying the glued wood strands to a conveyor belt by wind and / or throw sifting, and g) pressing the glued wood strands arranged on the conveyor belt. wherein the at least one flame retardant composition described above is applied, in particular sprayed, to the wood strands before, during or after the application of the binder to the wood strands.

[0077] As mentioned above, particle boards, also called OSB (oriented strand boards), are made from long strands of wood in a multi-stage process.

[0078] In a first step, strands of debarked roundwood, preferably softwood, are peeled lengthwise by rotating knives.

[0079] The wood strands produced in this way can have a length between 50 and 200 mm, preferably 70 to 180 mm, particularly preferably 90 to 150 mm; a width between 5 and 50 mm, preferably 10 to 30 mm, particularly preferably 15 to 20 mm; and a thickness between 0.1 and 2 mm, preferably between 0.3 and 1.5 mm, particularly preferably between 0.4 and 1 mm.

[0080] In one embodiment, the wood strands have, for example, a length between 150 and 200 mm, a width between 15 and 20 mm, a thickness between 0.5 and 1 mm and a moisture content of max. 50%.

[0081] OSB typically consists of two cover layers that border a middle layer, whereby the cover layers and middle layer can consist of different types of wood strands. For example, flat strands can be used in the cover layers, while lower quality strands (or even chips) can be used in the middle layer. It is preferred if the strands for the cover layers are mixed, e.g. sprayed, with the flame retardant present. Isocyanates are preferably used as binders for OSB. In one embodiment, the at least one isocyanate is based on aromatic polyisocyanates, in particular polydiphenylmethane diisocyanate (PMDI), tolylene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI), with PMDI being particularly preferred. However, melamine-urea-formaldehyde glues or phenol glues can also be used. Like PMDI, these have high water resistance.Melamine is also used as a flame retardant.

[0082] As already indicated, the at least one flame retardant can be applied, in particular sprayed, to the wood strands in a gluing drum (coil) or a trough mixer together with the addition of the binder.

[0083] A gluing device in the form of a coil used for the present process consists of a cylinder and at least one supply bar for the supply of adhesive and compressed air with spray discs, which are driven by pneumatic drive motors arranged in housings. Such a gluing device is described in DE 10 2008 046 637 A1.

[0084] A suitable trough mixer is available from Dieffenbacher, for example. These glue mixers ensure even glue distribution thanks to their large chamber volume and optimal material residence time. To ensure optimal gluing results, the mixer's constant fill level is maintained by an outlet flap.

[0085] The flame retardant composition can be used in both the outer layers and the middle layer, or only in the outer layers or only in the middle layer of the OSB.

[0086] After the binding agent with the flame retardant has been applied to the wood strands, the glued wood strands are placed on a conveyor belt or sprinkled and then pressed into an OSB wood-based panel.

[0087] Pressing can take place at a pressing temperature between 150 and 250°C, preferably between 180 and 220°C, and a pressing time between 30 and 240 seconds, preferably between 100 and 210 seconds, in particular between 150 and 180 seconds. The OSB produced by the present process thus comprises a binder and the flame retardant composition described above.

[0088] It was shown that the flame retardant content on the strands after scattering and pressing in the OSB was increased by up to 70% when the silane mixtures were used as fixatives compared to samples without fixatives.

[0089] The OSB produced using the described process has a transverse tensile strength of greater than 0.3 N / mm 2 , preferably greater than 0.4 N / mm 2 , preferably greater than 0.45 N / mm 2 , particularly preferably greater than 0.5 N / mm 2 The transverse tensile strength can be in a range between 0.3 and 0.6 N / mm2 , preferably between 0.4 and 0.6 N / mm 2 , particularly preferably between 0.45 and 0.55 N / mm 2 lay.

[0090] Furthermore, the particleboards (OSB) produced by the described process have longitudinal elastic moduli between 3200 and 4000 MPa, preferably between 3400 and 3800 MPa, and transverse elastic moduli between 1400 and 1800 MPa, preferably between 1500 and 1600 MPa.

[0091] This OSB wood-based panel can have a density between 300 and 1000 kg / m 3 , preferably between 500 and 800 kg / m 3 , particularly preferably between 600 and 700 kg / m 3 have.

[0092] The thickness of the present OSB wood-based panel can be between 5 and 50 mm, preferably between 8 and 40 mm, with a thickness between 8 and 30 mm being particularly preferred.

[0093] As mentioned above, it is also possible to produce particle boards using this process.

[0094] Accordingly, a method for producing wood particle boards is provided, comprising the following steps: a) producing wood chips from suitable woods, b) comminuting the wood chips by machining to obtain wood shavings; c) gluing the wood shavings with at least one binder; d) applying the glued wood shavings to a conveyor belt to form a multi-layered chip cake; and e) pressing the chip cake to form a wood-based panel. The at least one flame retardant composition described above is applied, in particular sprayed, to the wood shavings before, during, or after the application of the binder to the wood shavings.

[0095] The wood chips produced in the machining process are divided into fine and coarse chip material, with the larger wood chips being used preferentially in the middle layer of the particleboard, and the smaller wood chips being used preferentially in the outer layers. It is preferable for the wood chips for the outer layers to be treated, e.g., sprayed, with the flame retardant present.

[0096] In the case of particleboards, formaldehyde-based binders are preferably used, with binder amounts between 5 and 8 wt%, preferably between 6 and 7 wt%, being used for the middle layer and between 6 and 10 wt%, preferably between 8 and 9 wt%, being used for the top layer. When using a polyurethane-based binder, such as PMDI, in particleboards, the binder amount in the middle layer is between 2 and 5 wt%, preferably 3 wt%, and in the top layer between 4 and 8 wt%, preferably 5 wt%.

[0097] After gluing, the glued wood chips are scattered onto a conveyor belt, forming a chip cake. In the case of wood chips, a wind-dispersed method is typically used, with a first top layer being scattered, followed by the middle layer, and finally a second top layer.

[0098] The chip cake is then pre-pressed and then hot-pressed at temperatures between 100°C and 250°C, preferably between 130°C and 220°C, especially at 200°C. The present wood-based panel in the form of a chipboard can have a bulk density between 400 and 1200 kg / m 3 , preferably between 500 and 1000 kg / m 3 , particularly preferably between 600 and 800 kg / m 3 have.

[0099] The thickness of the present wood-based panel as a wood chipboard can be between 3 and 20 mm, preferably between 5 and 15 mm, with a thickness of 10 mm being particularly preferred.

[0100] The present wood chipboard consists of 60 to 90 wt%, preferably 70 to 80 wt% of wood chips and 5 to 20 wt%, preferably 10 to 15 wt% of binders.

[0101] The invention is explained in more detail below using several exemplary embodiments.

[0102] Example 1:

[0103] 5 wt% of ino®dur GW80-ND (30 wt%) is added to a phosphate / polyphosphate-based flame retardant (solids content: approx. 50 wt%).

[0104] Synthesis of the additive ino®dur GW80-ND:

[0105] The silanes are hydrolyzed using 15.23 g of glycidyloxypropyltriethoxysilane, 9.75 g of methyltriethoxysilane and 5.7 g of tetraethoxysilane using 1.67 g of a 0.1 molar sodium hydroxide solution.

[0106] After stirring for 60 minutes at 40 °C under reflux, 2.04 g of zirconium n-propoxide (70% in isopropanol) are added. After a further stirring time of 60 minutes at room temperature, 8.22 g of water are added dropwise, and 7.1 g of ethanol are evaporated using a rotary evaporator (T=55 °C and p min = 105 mbar).

[0107] More cost-effective synthesis: Due to price pressure, the solvent exchange step using a rotary evaporator was to be avoided and a more cost-effective silane mixture was to be used. For this purpose, the synthesis was adapted: Example 2: Flame-resistant OSB

[0108] 5 wt% of ino®dur GW80-N-D5 (30 wt%) is added to a phosphate / polyphosphate-based flame retardant (solids content: approx. 50 wt%).

[0109] Synthesis of the additive ino®dur GW80-N-D5:

[0110] The silanes are hydrolyzed using 7.61 g of glycidyloxypropyltriethoxysilane, 19.5 g of methyltriethoxysilane, and 11.4 g of tetraethoxysilane and 1.92 g of a 0.1 molar sodium hydroxide solution. After stirring for 60 minutes at 40 °C under reflux, 1.24 g of zirconium n-propoxide (70% in isopropanol) is added.

[0111] After a further stirring time of 60 minutes at room temperature, 15.78 g of a mixture consisting of 60 parts of water and 40 parts of dipropylene glycol methyl ether is added dropwise and stirred for a further 30 minutes at room temperature.

[0112] The finished additive now has a flash point of approximately 60 °C. Even adding 25 wt.% to the aqueous flame retardant (phosphate / polyphosphate) results in a flash point well above 70 °C, allowing it to be used without solvent replacement.

[0113] This mixture is then sprayed in a coil (glue drum) onto the top layer strands for an OSB in a quantity of 24 wt% (solid on wood dry). 5 wt% PMDI (100%) and 3 wt% paraffin emulsion (50 wt%) were also added. For the middle layer, strands in another coil were sprayed with 3.5 wt% PMDI (100%) and 3 wt% paraffin emulsion (50 wt%). After the strands have been spread, strands are taken from the top layer and analyzed for their flame retardant content. The result was 21 wt%. A blank sample without fixative only contained 15 wt%. The structure was run through a continuous press and pressed under pressure and temperature to form an OSB (22 mm). Board samples were pulled behind the press, and the flame retardant contents were also determined. There, the value for the sample with fixative was 20 wt% and for the sample without fixative, the value was 10 wt%.Example 3: Flame-retardant chipboard.

[0114] 5 wt% of ino®dur GW80-N-D5 (30 wt%) are added to a phosphate / polyphosphate-based flame retardant (solids content: approx. 50 wt%) (preparation as in Example 2).

[0115] This mixture is then sprayed onto the face layer of chipboard in a mixer at a rate of 20 wt% (solid on dry wood). 15 wt% urea-formaldehyde glue (as a 60% solution) and 2 wt% hot paraffin were also added. The glue contained an ammonium salt-based hardener at a rate of 5 wt% fl. / fl. (50% solution).

[0116] After spreading the top layers and the middle layer (gluing: 7 wt% urea-formaldehyde glue (solid on wood dry, 60% solution with ammonium salt-based hardener (5 wt% fl / on glue fl)), 2 wt% hot paraffin was also added to the middle layer chips. The gluing was carried out in a trough mixer, just as for the top layer.

[0117] After the top and middle layers were sprinkled, chips were taken from the top layer and analyzed for flame retardant content. The result was 16 wt%. A blank sample without a fixative was found to contain only 13 wt%. The chips were pressed into a three-layer particle board (18 mm) in a continuous press. Panel samples were drawn downstream of the press, and the flame retardant content was also determined. The result was 15 wt% for the top layer sample with a fixative and 12 wt% for the sample without a fixative.

Claims

Patent claims 1. A process for producing a wood-based panel from wood particles, wherein at least one flame retardant in the form of a suspension is applied to the wood particles during the production process, wherein the flame retardant suspension comprises - at least one phosphate salt and / or sulfate, - a mixture of at least one compound of general formula (I) R 1 aSiX(4-a) (I), where - X is alkoxy, and - R 1 an organic radical is selected from the group comprising alkyl, cycloalkyl or phenyl, and - a = 1, 2, 3, in particular 1 or 2, - at least one compound of general formula (II) SiX4(II), where X is alkoxy, and - at least one compound of the general formula (III) R 2 SiX3(III), where - X is alkoxy, and - R 2an organic radical is selected from the group comprising C1 -C10 alkyl, which may be interrupted by -O- or -NH-, and - where R 2 has at least one functional group Qi selected from a group containing a methacrylic, methacryloxy, vinyl, and epoxy group. Process according to claim 1, characterized in that X is selected from a group containing C 1-6 alkoxy, in particular methoxy, ethoxy, n-propoxy, i-propoxy, and butoxy. Process according to one of the preceding claims, characterized in that R 1 the compound of general formula (I) is selected from a group comprising C1-C10 alkyl, preferably C1-C8 alkyl, particularly preferably methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl. Process according to one of the preceding claims, characterized in that the compound of general formula (I) R 1 SiX3or R 1 2SiX2with R 1as a C1-C10 alkyl group, preferably methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, and with X as alkoxy, in particular methoxy, ethoxy, n-propoxy or i-propoxy. Process according to one of the preceding claims, characterized in that R 2 the compound of general formula (III) is selected from a group comprising methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, which may be interrupted by -O- or -NH-. Process according to one of the preceding claims, characterized in that the at least one functional group Q 1the compound of general formula (III) is selected from a group containing epoxy, amino, and vinyl groups. Process according to one of the preceding claims, characterized in that the silane mixture comprises 5-25 wt.%, preferably 10-20 wt.% of at least one silane of formula (I), 3-15 wt.%, preferably 6-11 wt.% of at least one silane of formula (II), and 5-20 wt.%, preferably 8-15 wt.% of at least one silane of formula (III). Process according to one of the preceding claims, characterized in that the at least one phosphate salt is a monophosphate or polyphosphate, or a mixture with a sulfate. Process according to one of the preceding claims, characterized in that at least one glycol ether is present, in particular dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, 1-methoxy-2-propanol, tripropylene glycol monobutyl ether, propylene glycol butyl ether, ethylene glycol monophenyl ether. Process according to one of the preceding claims, characterized by at least one metal alkoxide, in particular a zirconium alkoxide, such as zirconium n-propoxide. Process according to one of the preceding claims, characterized in that the at least one wood-based panel is a coarse-grained strand board (OSB), particle board, or plywood panel. Process according to one of the preceding claims, characterized by the following steps: -Providing wood particles, in particular dried wood particles; -Gluing the wood particles with a suitable binder, - Pressing the glued wood particles to form a wood-based panel, characterized in that the at least one flame retardant is applied, in particular sprayed, to the wood particles before, with or after the application of the binder to the wood particles. OSB board producible in a process according to any one of claims 1-12. Particle board producible in a process according to any one of claims 1-12. A process for producing a flame retardant according to any one of claims 1-12, comprising the following steps: a) Providing an aqueous suspension containing a mixture of at least one compound of the general formula (I), at least one compound of general formula (II) and at least one compound of general formula (III); b) adding at least one catalyst, in particular a basic compound, to the suspension of at least one compound of formula (I), formula (II) and formula (III); c) heating the mixture of at least one compound of formula (I), formula (II) and formula (III) and the at least one catalyst; d) adding at least one metal alkoxide, in particular a zirconium alkoxide, to the mixture, and e1) either separating the alcoholic phase formed (e.g. by evaporation) from the aqueous phase of the mixture of at least one compound of formula (I), formula (II) and formula (III) or e2) adding a mixture of water and at least one glycol methyl ether, and f) adding at least one phosphate to the mixture obtained in step e1) or step e2).