Method for producing OSB and OSB production device

Description

[0001] The invention relates to a method for producing, in particular flame-retardant, OSB (oriented strand board), which can also be referred to as coarse chipboard.

[0002] According to a second aspect, the invention relates to an OSB production device comprising (a) a coarse chip production device for producing coarse chips from wood, (b) a dryer for drying the coarse chips, which is connected to the coarse chip production device, (c) a belt conveyor arranged downstream of the dryer in the material flow direction, (d) a first distribution device for distributing coarse chips on the belt conveyor to form a first covering layer, (e) a second distribution device for distributing coarse chips to form a second covering layer above the first covering layer, thus forming a chip layer, and (d) a press for pressing the chip layer into an OSB board. The OSB production device can also be referred to as a coarse chipboard production device.

[0003] It is advantageous to use as little flame retardant as possible in the production of flame-resistant OSB, as this is a considerable expense. One reason for this is that flame retardants themselves are expensive. Furthermore, flame retardants require more glue to achieve the same mechanical strength as a non-flame-resistant OSB board, which is also undesirable. Furthermore, most flame retardants are poorly soluble in water, so incorporating the flame retardant into the chips also introduces large amounts of water, which often must be removed during subsequent processing.

[0004] EP 3 470191 A1 describes a method for producing a wood-based panel in which coarse chips are first coated with glue and then scattered into particles. During the scattering of the wood particles, additional adhesive is applied in varying amounts to all or only some of the wood particles. A flame-retardant substance can also be added.

[0005] WO 2015 / 061905 A1 describes a process in which a porous cover layer, for example made of cardboard or paper, is impregnated with a flame retardant and placed on layers of coarse chips, which are then pressed together. In addition to this layer of flame-retardant-impregnated cover layer, the coarse chips themselves can also be treated with a flame retardant.

[0006] EP 3 181 313 A1 discloses a method for applying a liquid, possibly containing surfactant, to a fiber cake, in which the amount of liquid applied is monitored by means of an infrared camera.

[0007] US 2004 / 0028 934 A1 describes a process in which flame retardants are applied to dried coarse chips. After the flame retardant is applied, the coarse chips are dried and compressed.

[0008] US 2020 / 0181 448 A1 describes a process in which a dispersion of boric acid and urea is used as a flame retardant for a wood-based panel.

[0009] US Pat. No. 3,438,847 describes a process in which a boron-containing flame retardant is introduced into the chips in a solution. A binder mixed with boric acid is then added, and the chips are subsequently scattered and pressed.

[0010] The invention is based on the object of improving the production of flame-retardant wood-based panels, in particular OSB.

[0011] The invention solves the problem by a method having the features of claim 1.

[0012] When coarse chips are mentioned below, normal chips which are not coarse chips are meant within the scope of this most general form of the invention.

[0013] According to a second aspect, the invention solves the problem by an OSB manufacturing device having the features of claim 8.

[0014] When OSB is mentioned below, wood-based panels are generally meant within the scope of this most general form of the invention; when a coarse chip production device is mentioned, a chip production device is generally meant.

[0015] The first flame retardant liquid application device is preferably arranged in the material flow direction upstream of the second flame retardant liquid application device and / or upstream of the second distribution device.

[0016] An advantage of the invention is that, compared to spraying the flame retardant liquid into a mixer, spray losses are generally lower. Furthermore, there is generally no loss of flame retardant due to chips rubbing against each other or against components of the OSB production device.

[0017] Another advantage is that only a short distance is required between the location where the flame retardant liquid is applied and a press for compressing the particle layer. According to a preferred embodiment, this distance is less than 30 m. This reduces the waste of OSB with a sufficiently high flame retardant content, particularly during start-up or when switching to the production of flame-resistant OSB. This allows both flame-resistant OSB and non-OSB to be produced using the same OSB production equipment. Furthermore, the reaction time between the glue and the flame retardant, or the water in the flame retardant, is shortened.

[0018] In the context of this description, coarse chips are understood to mean, in particular, wood chips that are in the size range 200±30 mm x 20±4 mm x 0.5±0.2 mm.

[0019] In particular, the method according to the invention is a method for producing flame-retardant OSB according to DIN EN 13823 (single burner item) or flame-retardant OSB according to DIN EN 13501-1.

[0020] The flame retardant liquid is preferably an aqueous solution. The flame retardant liquid preferably contains at least one organic or inorganic phosphorus-containing and / or nitrogen-containing compound. The flame retardant is preferably boron-free.

[0021] Pressing the chip layer means, in particular, that at least the coarse chips are compressed. In particular, it is possible for additional chips that are not coarse chips to be compressed with the coarse chips. Furthermore, it is possible, and represents a preferred embodiment, for a first top layer and a second top layer to be scattered from the coarse chips and pressed together with a middle layer arranged between the two top layers to form the OSB.

[0022] Pressing is understood to mean pressing using a belt press. In other words, the press is preferably a belt press.

[0023] The flame retardant liquid is understood in particular to mean a solution, emulsion or dispersion containing flame retardants in a liquid phase, in particular a solvent.

[0024] The application of the flame retardant liquid to the coarse chips is understood in particular to mean spraying, pouring or jetting.

[0025] The distribution of coarse chips on the belt conveyor is understood in particular to mean the distribution of the coarse chips on a conveyor belt of the belt conveyor.

[0026] The feature that the second flame retardant liquid application device is arranged to apply a flame retardant liquid to the second cover layer is understood, in particular, to mean that the flame retardant is applied in such a way that it wets the second cover layer, but preferably not the first cover layer or any existing middle layer. In particular, application to the cover layer does not only mean application above the cover layer.

[0027] A conveyor belt is understood, in particular, to be a flexible component for continuous conveying. It is possible, but not necessary, for the conveyor belt to be made of metal, a mesh structure, a textile, or an entropy-elastic material, such as rubber.

[0028] The term is used as a generic term for top layer, middle layer and chip layer.

[0029] A chip layer is defined as a layer of chips. This can be the top layer, the middle layer, or the chip layer, but also two or three of these layers, or possibly additional layers of chips.

[0030] According to a preferred embodiment, the method comprises the step of drying the coarse chips prior to gluing. By first gluing the coarse chips and then applying the flame retardant, losses of flame retardant, particularly through abrasion, are reduced.

[0031] According to a preferred embodiment, the method comprises the steps of (a) producing top chips, in particular in the form of coarse chips, and middle layer chips, (b) optionally drying, in particular drying together, the coarse chips and middle layer chips, (c) optionally separating coarse chips and middle layer chips, in particular dried coarse chips and middle layer chips, (d) producing a first top layer from coarse chips, (e) applying the flame retardant liquid to the top layer, (f) producing a middle layer above the top layer from middle layer chips, (g) producing a second top layer from top chips above the middle layer to form the chip layer, and (h) applying the flame retardant liquid to the second top layer. The first top layer, the second top layer, and the middle layer, which form a chip layer, are then preferably pressed together to form OSB.

[0032] It is possible, but not necessary, for the middle layer chips to also be coarse chips. In particular, it is possible for the middle layer chips to have a length distribution density, where the length distribution density indicates the number of coarse chips with a certain length. The length distribution density preferably has a middle layer chip length median that is smaller than a top layer chip length median of the length distribution density of the top chips. In other words, the chips that form the top layers are longer than the chips that form the middle layer.

[0033] It is possible, but not necessary, to apply a flame retardant liquid to the middle layer as well. In particular, no flame retardant liquid is applied to the middle layer. In this case, the flame retardant is concentrated in the outer layers, thereby achieving particularly high flammability while simultaneously maintaining a low flame retardant content in the OSB.

[0034] Preferably, the method comprises the steps of (a) detecting a moisture content of the OSB and / or the chip layer after application of the flame retardant and (b) changing an application amount of flame retardant liquid and / or a flame retardant concentration of flame retardant in the flame retardant liquid such that the chip layer moisture content lies within a predetermined target moisture content interval and a flame retardant content of the chip layer and / or the OSB lies within a predetermined target flame retardant content interval.

[0035] In particular, the method preferably comprises the steps of (a) detecting a top layer moisture content of the first top layer and / or the second top layer after application of the flame retardant and (b) changing the application amount of flame retardant liquid and / or the flame retardant concentration of the flame retardant in the flame retardant liquid so that the top layer moisture content lies within a predetermined target top layer moisture content interval.

[0036] The flame retardant concentration can be reduced, for example, by adding solvent, especially water, to the flame retardant liquid.

[0037] Increasing the flame retardant concentration is achieved, for example, by reducing the amount of solvent added. Alternatively, increasing the flame retardant concentration can involve increasing the temperature of the flame retardant liquid if—as provided in a preferred embodiment—the flame retardant is present at its saturation concentration in the flame retardant liquid. For example, the solvent is passed through a bath of solid flame retardant. The higher the solvent temperature, the higher the flame retardant concentration.

[0038] The chip layer has a chip layer temperature, the top layer a top layer temperature, and the middle layer a middle layer temperature. These temperatures refer to a position in the direction of material flow immediately upstream of the point where the flame retardant liquid is applied. In each case, they are the average temperature across the full width of the respective layer.

[0039] Preferably, the temperature of the flame retardant liquid and the flame retardant concentration are selected such that cooling the flame retardant liquid to the respective temperature (chip layer temperature, top layer temperature, or middle layer temperature) results in the flame retardant content at this temperature being below the solubility of the flame retardant. This way, little solvent is introduced into the corresponding layer.

[0040] When applied to the respective layer, the flame retardant liquid preferably has a temperature of at least 50°C, in particular at least 60°C, preferably 70°C, and particularly preferably at least 80°C. A high temperature generally increases the solubility of the flame retardant in the solvent, so that less solvent, usually water, is needed to dissolve a given amount of flame retardant. Furthermore, the viscosity of water decreases with increasing temperature, so that the flame retardant liquid can penetrate the coarse chips more easily.

[0041] It is advantageous if the flame retardant liquid contains a flame retardant concentration that corresponds to at least 60%, in particular at least 70%, preferably at least 80%, particularly preferably at least 90%, of the maximum solubility of the flame retardant at the corresponding temperature. A further advantage is that the heated flame retardant causes the two outer layers to experience a temperature increase, which enables a higher press speed.

[0042] It is advantageous if the flame retardant fluid contains a viscosity reducer, especially a surfactant. This allows the flame retardant fluid, and thus the flame retardant, to penetrate the chips more quickly. The flame retardant fluid preferably contains a viscosity reducer.

[0043] It is advantageous if the method comprises the step of applying a pressure difference to the chip layer, top layer, or middle layer that is or will be wetted with the flame retardant liquid. Applying the pressure difference may comprise applying a negative pressure, in particular to an underside of the belt conveyor on an upper side of the chip layer, top layer, or middle layer.

[0044] The advantage of this is that the consumption of flame retardant can generally be reduced compared to conventionally manufactured OSB. By applying a pressure differential to the coarse chips, the flame retardant liquid is at least partially absorbed into the coarse chips. This reduces the formation of a crust of flame retardant on the coarse chips. If the flame retardant at least partially penetrates the coarse chips, its effectiveness is increased.

[0045] By sucking and / or injecting the flame retardant liquid into the coarse chips, there are often fewer chemical reactions with the glue. Therefore, the glue quantity usually needs to be increased significantly less to compensate for the loss of strength caused by the addition of the flame retardant.

[0046] Applying a pressure difference by applying overpressure means, in particular, creating a pressure difference between a first side surface of the coarse chips and the opposite side surface of the coarse chips. The two side surfaces are spaced apart by the height of the coarse chips, which is preferably 0.5 ± 0.2 cm.

[0047] The application of the pressure difference by applying negative pressure is understood in particular to mean that a pressure is applied to the coarse chips, in particular to the covering layer, which is at least 200 hPa, preferably at least 400 hPa, particularly preferably at least 600 hPa, lower than the ambient pressure.

[0048] Gluing is preferably carried out without a pressure difference applied to the coarse chips.

[0049] Preferably, the negative pressure is applied to the underside of a conveyor belt of the belt conveyor. For this purpose, the conveyor belt is gas-permeable. For example, the conveyor belt is perforated or made of a gas-permeable material, such as a textile. Alternatively, the conveyor belt can be a metal belt. This metal belt is preferably perforated.

[0050] The overpressure is applied, for example, by the layer first passing through a roller that acts as a seal, and then entering a positive pressure zone where the overpressure is applied. The layer lies on a gas-permeable conveyor belt, the side of which, facing away from the positive pressure zone, is subjected to a lower pressure, such as ambient pressure or negative pressure. The layer leaves the positive pressure zone by passing through a roller that acts as a seal.

[0051] Preferably, the coarse chips are dried until they are kiln-dry. In this state, the flame retardant liquid is absorbed particularly easily and quickly by the dried coarse chips. According to a preferred embodiment, the coarse chips containing the flame retardant are not dried significantly. This means, in particular, that the moisture content of the respective layer (top layer, middle layer, or chip layer) changes by a maximum of five percentage points, in particular by a maximum of two percentage points, after application of the flame retardant liquid.

[0052] The coarse chip layer preferably has a chip layer thickness that is at most four times, preferably at most three times, and more preferably at most twice the thickness of a single coarse chip layer. The coarse chip layer thickness is the minimum achievable thickness of a coarse chip layer. This is the average height of an arrangement of coarse chips on a flat, horizontally extending test area of ​​1 m², whereby for this arrangement, sections of two or more coarse chips lie on top of one another on a maximum of 75% of the test area, and whereby at least 90%, preferably at least 95%, and in particular 100%, of the test area is covered by coarse chips.

[0053] The flame retardant liquid preferably contains a dye. This dye is preferably colorless in the visible range. In this case, the dye can also be referred to as a marker. It is advantageous if the dye absorbs and / or fluoresces in the UV range. In this case, the flame retardant distribution of the flame retardant liquid and / or the flame retardant can be determined by irradiating it with UV light and / or taking an image of the respective layer and / or the OSB board with a camera sensitive to the UV range.

[0054] According to a preferred embodiment, a process parameter in the form of the conveyor belt speed and / or the pressure difference and / or an area-specific application rate of flame retardant liquid is controlled based on the flame retardant distribution. In other words, a deviation between a target flame retardant distribution and the measured actual flame retardant distribution is determined, and at least one of the aforementioned parameters is controlled such that the deviation is minimized.

[0055] An OSB production device according to the invention preferably has a third distribution device for distributing chips so that a middle layer is created above the first cover layer. In particular, the third distribution device is designed such that the middle layer lies on the first cover layer. The second distribution device is then preferably designed such that the second cover layer lies on the middle layer. Accordingly, the second distribution device is preferably arranged downstream of the third distribution device in the material flow direction.

[0056] The OSB production device preferably has a hopper, which is arranged downstream of the coarse chip production device and preferably downstream of a dryer for the coarse chips in the direction of material flow. The hopper is preferably arranged upstream of the distribution devices in the direction of material flow. In other words, the distribution devices distribute glued chips. The hopper is preferably a rotating gluing drum or a mixer, in particular a trough mixer.

[0057] The OSB production device preferably has a classifier for separating the top layer chips from the middle layer chips. The classifier is preferably a sifter. It is advantageous if the classifier is located downstream of the coarse chip production device and / or upstream of the hopper in the direction of material flow.

[0058] The pressure differential generator for applying the pressure difference to the chip layer preferably comprises a vacuum generator and / or a positive pressure generator. The differential pressure generator preferably has a vacuum pump and at least one suction chamber, preferably at least two suction chambers, in particular a plurality of suction chambers, each of which is connected to the vacuum pump via a valve. The valves are preferably designed to increase their valve opening degree as the pressure in the suction chamber decreases. In other words, the lower the pressure in the respective suction chamber, the wider the valves open.

[0059] The suction chambers are arranged in particular in such a way that at least 90% of the area, preferably at least 95% of the area, particularly preferably 100% of the area of ​​the coarse chipping system can be subjected to the pressure difference, in the present case to a negative pressure, by means of at least one suction chamber each, for at least a predetermined time of, for example, 1 second, in particular at least 5 seconds.

[0060] Preferably, a negative pressure is at least 300 hPa (and the pressure is therefore 713 hPa), in particular at least 500 hPa (and the pressure is therefore 513 hPa).

[0061] It is advantageous if the OSB production facility has an inspection system for detecting the flame retardant distribution in each layer. This can be the distribution of the flame retardant across the surface of the coarse particle layer, i.e., the two-dimensional distribution in the longitudinal and width directions of the coarse particle layer, but not in the thickness direction.

[0062] Alternatively or additionally, the inspection system can be designed to detect the flame retardant distribution in the OSB. This can then be the distribution of the flame retardant across the surface of the OSB, i.e., the two-dimensional distribution in the longitudinal and width directions of the coarse particle layer, and / or the distribution of the flame retardant in the thickness direction.

[0063] The inspection system preferably has a camera for capturing UV light and / or fluorescent light generated when the coarse particle board layer or OSB is irradiated with UV light. Preferably, the inspection system also has a UV light source for irradiating the coarse particle board layer or OSB with UV light.

[0064] The OSB production device preferably comprises a moisture meter for measuring the moisture content of a chip layer, in particular the first cover layer and / or the second cover layer. The moisture meter is preferably designed for spatially resolved measurement of the moisture content of the chip layer. This moisture meter can, for example, comprise an infrared light source and an infrared camera. The infrared light source is preferably designed to emit infrared radiation with a wavelength of 3±0.5 µm. In this wavelength range, water absorbs infrared light particularly strongly and reflects it correspondingly very little.

[0065] Particularly preferably, the OSB production device has a control system which is designed to automatically control the first flame retardant liquid application device and / or the second flame retardant liquid application device to change an application quantity of flame retardant liquid and / or a concentration of the flame retardant, so that the chip layer moisture content lies within a predetermined target moisture content interval and a flame retardant content of the chip layer and / or the OSB lies within a predetermined target flame retardant content interval.

[0066] It is advantageous if at least one of the flame retardant liquid application devices has at least two, in particular a plurality, of nozzles that can be individually controlled by the control system. The control system is then configured to control the nozzles of the flame retardant liquid application device so that the actual spatial distribution of the flame retardant deviates as little as possible from a predetermined target distribution, in particular a spatially constant concentration of flame retardant.

[0067] The flame retardant liquid application device preferably comprises a temperature control designed to automatically set a target temperature and / or a concentration control for setting a target concentration of flame retardant in the solvent. The solvent is preferably water. The temperature can be used to adjust the saturation concentration of the flame retardant in the water. If—as provided according to a preferred embodiment—the flame retardant application device is set up to apply a flame retardant liquid whose concentration of flame retardant corresponds to the saturation limit, the concentration of flame retardant can be increased by increasing the temperature.

[0068] The invention is explained in more detail below with reference to the accompanying drawings. Figure 1 shows a flow diagram of a method according to the invention and Figure 2 shows a schematic view of an OSB manufacturing device according to the invention for carrying out a method according to the invention.

[0069] Figure 1 schematically shows a wood-based panel manufacturing device according to the invention, here in the form of an OSB manufacturing device 10, which has a chip manufacturing device, here in the form of a coarse chip manufacturing device 12, which first debarks wood 14 in a debarker 16 and then chips it in a chipper 18 into chips, here in the form of coarse chips 20. In a dryer 22, the chips 20 are dried, preferably to a kiln-dry state.

[0070] In a classifier 24, which in the present case is designed as a sifter, top chips 26 are separated from middle layer chips 28. The middle layer chips are smaller, in particular shorter, than the top chips 26. A hopper 30, for example a rotating gluing drum or a mixer, in particular a trough mixer, is arranged downstream of the classifier 24 in the material flow direction M. In the present case, the hopper comprises a top layer chip gluing unit 30a and a middle layer chip gluing unit 30b, which respectively apply glue to the top chips 26 and the middle layer chips 28.

[0071] Cover chips 26, which can also be referred to as cover layer chips, are scattered by a first distribution device 32.1 onto a first cover layer 34.1. A first flame retardant liquid application device 36.1 applies a schematically depicted flame retardant liquid 38 to the first cover layer 34.

[0072] Cover chips 26 are also scattered by a second distribution device 32.2 to form a second cover layer 34.2. A schematically illustrated flame retardant liquid 38 is applied to the first cover layer 34 by means of a second flame retardant liquid application device 36.2.

[0073] By means of a second flame retardant liquid application device 36.2, a schematically drawn flame retardant liquid 38 is applied to the second cover layer 34.2.

[0074] Middle layer chips 38 are scattered onto the first cover layer 4 30.1 by means of a third distribution device 32.3, so that they form a middle layer 40. It is possible, but not necessary and in the Figure 1 In the embodiment shown, it is not provided that flame retardant 38 is applied to the middle layer by means of a flame retardant liquid application device.

[0075] The first cover layer 34.1, the middle layer 40 and the second cover layer 34.2 together form a chip layer 42, which is pressed into an OSB 46 by means of a hot press 44.

[0076] Figure 2 shows a schematic view of the OSB manufacturing device 10 in a side view. The flame retardant liquid application devices 36.1, 36.2 have together or - as in Figure 1 shown - a reservoir 50.1, 50.2 in which the flame retardant liquid 38 is contained. By means of a heater 52.1, 52.2, the flame retardant liquid 38 can be brought to a predetermined temperature T 28 , for which, for example, 50°C ≤ T 28 ≤ 95°C applies.

[0077] By means of a metering pump 54.1, the flame retardant liquid 38 is fed to nozzles 56.k (k = 1, 2, ...) of the respective flame retardant liquid application device, in this case the first flame retardant liquid application device 36.1 (see Figure 3 ), which are arranged next to each other transversely to the material flow direction M, and from there sprayed onto the first cover layer 34.1.

[0078] To improve the introduction of the flame retardant liquid 38, the OSB production device 10 can have a pressure difference generator 58 designed to apply a pressure difference to the first cover layer 34.1. This produces coarse chips 20 containing the flame retardant.

[0079] How Figure 3As shown, the pressure difference generator 58 has, for example, a vacuum pump 60 connected to a plurality of suction chambers 62.j (j = 1, 2, ...). When the vacuum pump 60 is operating, a pressure pj of, for example, 100 hPa ≤ pj ≤ 800 hPa is therefore present at the suction chambers 62.j. It is possible that the pressures in the individual suction chambers 62.j differ from one another. Valves (not shown) can be used for this purpose.

[0080] The suction chambers 62.j are located on a conveyor belt 64, in particular a metal belt, of a belt conveyor 66, which has openings, for example holes. As a result, the pressure pj is applied to the first cover layer 34.1.

[0081] A first inspection system 70.1, which has a camera 72.1, can be arranged downstream of the pressure difference generator 58 in the material flow direction M. The camera 72 detects light that is reflected, emitted, and / or not absorbed by a dye in the flame retardant liquid 38. Alternatively or additionally, the camera 72.1 detects fluorescent light. In this way, an actual flame retardant distribution k ist (x,y) is determined, which indicates a concentration k of flame retardant as a function of the surface coordinates x, y. Again alternatively or additionally, the camera 72.1 can be designed as a moisture meter and measure the moisture distribution in the cover layer 34.1 based on reflected or absorbed IR light.

[0082] A control 74 compares the actual flame retardant distribution k ist (x,y) with a target flame retardant distribution k soll (x,y) and controls the nozzles 56.k individually so that a deviation between the actual flame retardant distribution k ist (x,y) and the target flame retardant distribution k soll (x,y) is minimized.

[0083] It is possible, but not necessary, for the inspection system to have a UV light source 76.1 that illuminates the cover layer 22 in a field of view G of the camera 72.1. The field of view G is the area of ​​the cover layer 34.1 that is recorded by the camera 72.

[0084] Figure 1 shows that - regardless of other features of this embodiment - a cutting device 78 can be arranged behind the hot press 44 in the material flow direction, which cuts the OSB board 46 into individual board segments 80.I. In this case, it is advantageous if a second inspection system 82 (see Figure 3), whose camera 84 records a section 86 of the respective plate segment 80.1. From this, a second actual flame retardant distribution k ist,2 (y,z) is determined, which also encodes the depth dependence of the flame retardant concentration k. In other words, the second actual flame retardant distribution k ist,2 (y,z) encodes a depth profile of the dye.

[0085] The control 74 is designed to change the pressures pj in the at least one suction chamber 60.j and / or a conveyor belt speed v 62 of the conveyor belt 62, so that the second actual flame retardant distribution k ist,2 (y,z) approaches a second desired flame retardant distribution k soll,2 (y,z). List of reference symbols

[0086] 10 OSB manufacturing device 54 Dosing pump 12 Coarse chip production device 56 nozzle 14 Wood 58 Pressure difference generator 16 Debarker 18 Machinists 60 vacuum pump 62 suction chamber 20 chips 64 conveyor belt 22 dryer 66 Belt conveyor 24 Classifier 70 Inspection system 26 Deck shavings 72 camera 28 Middle layer chips 74 control 30 Beleimer 76 UV light source 30a Top layer chipboard gluing unit 78 Cutting device 30b Middle layer chipboard gluing unit 32.1 first distribution device 80 Plate segment 32.2 second distribution device 82 second inspection system 32.3 third distribution device 84 second camera 34.1 first top layer 86 Cutting surface 34.2 second top layer 36 Flame retardant liquid application device G field of vision j.k,l Running index 38 Flame retardant liquid k is (x,y) Actual flame retardant distribution 40 middle class k should (x,y) Target flame retardant distribution 42 chip layer 44 hot press k is,2 (y,z) second actual flame retardant distribution 46 OSB board k soll,22 (y,z) second target flame retardant distribution 50 reservoir M Material flow direction 52 Heating p Pressure

Claims

1. A method for producing OSB (46) comprising the steps: (a) producing coarse chips, (b) glueing the coarse chips, thus obtaining glued coarse chips, (c) arranging the glued coarse chips on a transport belt (64), thus obtaining a chipboard layer (42), (d) applying a flame-retardant liquid to the chipboard layer (42), (e) applying a pressure difference to the chipboard layer (42) that is or will be wetted by applying a negative pressure to a lower side of the transport belt (64) and / or an overpressure to an upper side of the chipboard layer (42) and (f) pressing the chipboard layer (42), resulting in the OSB (46).

2. The method according to claim 1, characterised by the steps: (a) producing cover chips (26) in the form of coarse chips and middle layer chips (28), (b) producing a first surface layer (34.1) made of cover chips (26), (c) applying the flame-retardant liquid to the first surface layer (34.1), (d) producing a middle layer (40) of middle layer chips (28) above the first surface layer (34.1), (e) producing a second surface layer (36.2) of cover chips (26) above the middle layer (40), thereby obtaining the chipboard layer (42), and (f) applying the flame-retardant liquid to the second surface layer (34.2).

3. The method according to one of the preceding claims, characterised by the steps: (a) detecting a chipboard layer moisture content of the chipboard layer (42) following application of the flame retardant and (b) changing an application quantity of flame-retardant liquid and / or a concentration of the flame retardant so that the chipboard layer moisture content lies within a predetermined target moisture range and a flame retardant content in the cover layer (42) and / or the OSB (46) lies within a predetermined target flame retardant content range.

4. The method according to one of the preceding claims, characterised in that the flame-retardant liquid (a) has a temperature of at least 50°C when being applied to the chipboard layer (42) and / or (b) contains a viscosity reducer, especially a surfactant.

5. The method according to one of the preceding claims, characterised in that a chipboard layer thickness of the chipboard layer (42) corresponds at most to four times a coarse chipboard layer thickness of a coarse chipboard layer.

6. The method according to one of the preceding claims 2 to 5, characterised in that (a) the flame-retardant liquid contains a colouring agent, especially one that is colourless and that absorbs or fluoresces in the UV range, and (b) the method comprises the following steps: (i) depth-dependent, in particular optical detection of a colouring agent concentration of the chipboard layer (42) and / or the OSB panel (46), thus obtaining a colouring agent depth profile, and (ii) controlling a transport belt speed, a pressure difference and / or an area-specific application amount of flame retardant liquid using the colouring agent depth profile.

7. An OSB production device (10) with (a) a coarse chip production device (12) for producing coarse chips from wood (14), (b) a dryer (22) for drying the coarse chips that is connected to the coarse chip production device (12), (c) a belt conveyor (66) that is arranged downstream of the dryer (22) in the direction of material flow (M), (d) a first distribution device (32.1) for distributing coarse chips on the belt conveyor (66), resulting in a first surface layer (34.1), (e) a second distribution device (32.2) for distributing coarse chips, thus obtaining a second surface layer (34.2) above the first surface layer (34.1), resulting in a chipboard layer (42), (f) a press for pressing the chipboard layer (42) to form an OSB panel (46), (g) a first flame-retardant liquid application device arranged to apply a flame-retardant liquid to the first surface layer (34.1), and (h) a second flame-retardant liquid application device arranged to apply a flame-retardant liquid to the second surface layer (34.2), characterised by (i) a pressure difference generator (58) for applying a pressure difference to the chipboard layer which comprises - a negative pressure pump (60) and at least one suction chamber (62), each of which is connected to the negative pressure pump (60) via a valve, and / or - a pressure pump and a plurality of pressure chambers, each of which is connected to the pressure pump via a valve.

8. The OSB production device (10) according to claim 7, characterised by a third distribution device (32.3) for distributing chips (20), resulting in a middle layer (40) above the first surface layer (34.1), wherein the second distribution device (32.2) is arranged downstream of the third distribution device (32.3) in the direction of material flow (M) (second surface layer (34.3) is above the middle layer (40)).

9. The OSB production device (10) according to claim 7 or 8, characterised by (a) a gluer (30), which is arranged downstream of the coarse chip production device (12) and in particular downstream of the dryer (22) and upstream of the at least one distribution device (32) in the direction of material flow (M) and / or (b) a classifier (24) for separating cover chips (26) and middle layer chips (28) which is arranged downstream of the coarse chip production device (12) and upstream of the gluer (30) in the direction of material flow (M).

10. The OSB production device (10) according to one of the claims 7 to 9, characterised by an inspection system (70) for detecting a flame retardant distribution of flame retardant in the chipboard layer (42) and / or in the OSB (46).

11. The OSB production device according to claim 10,characterised in that the inspection system (70) comprises (a) a UV light source (76) and (b) a camera (72) for detecting reflected UV light and / or fluorescent light.

12. The OSB production device (10) according to one of the claims 7 to 11, characterised by (a) a moisture gauge for measuring a chipboard layer moisture content of the chipboard layer (42), in particular of the first surface layer (34.1) and / or the second surface layer (34.2), and (b) a controller (74) that is designed to automatically control the first flame-retardant liquid application device and / or the second flame-retardant liquid application device for changing an application quantity of flame-retardant liquid and / or a concentration of the flame retardant so that the chipboard layer moisture content lies within a predetermined target moisture range and a flame retardant content in the surface layer (42) and / or the OSB (46) lies within a predetermined target flame retardant content range.

13. The OSB production device (10) according to claim 8 or 11, characterised by a controller (74) that is designed to automatically control a transport belt speed, the pressure difference and / or an area-specific application quantity of flame-retardant liquid using the flame retardant distribution.

14. The OSB production device (10) according to one of the preceding claims 7 to 13, characterised in that the valves have a degree of valve opening that increases as pressure (p) decreases in the suction chambers (62).