METHOD FOR PRODUCING A WOODEN COMPOSITE BOARD, AND DEVICE FOR PRODUCING A WOODEN COMPOSITE BOARD

Abstract

The disclosure relates to a method for producing a wood-based material panel with the steps: producing a raw wood-based material panel which includes a first lateral surface and a second lateral surface that runs parallel to the first lateral surface, and edge surfaces that connect the lateral surfaces to each other; applying a liquid containing a flame retardant at least to the first lateral surface; and applying a negative pressure to the second lateral surface so that the liquid containing the flame retardant is sucked into a peripheral zone of the raw wood-based material panel, and/or applying an overpressure to the first lateral surface so that the liquid containing the flame retardant is pressed into a peripheral zone of the raw wood-based material panel, resulting in the wood-based material panel.

Claims

1. A method for producing a wood-based material panel; comprising: (a) producing a raw wood-based material panel that comprises a first lateral surface, a second lateral surface that extends parallel to the first lateral surface, and edge surfaces that connect the first and second lateral surfaces to each other, (b) applying a liquid containing a flame retardant to at least the first lateral surface, and (c) applying a negative pressure to the second lateral surface so that the liquid containing flame retardant is sucked into a peripheral zone of the raw wood-based material panel, and/or applying an overpressure to the first lateral surface so that the liquid containing flame retardant is pressed into a peripheral zone of the raw wood-based material panel, resulting in the wood-based material panel.

2. The method according to claim 1, further comprising locally applying the overpressure and applying the liquid containing flame retardant in an area of the overpressure.

3. The method according to claim 1, further comprising: (a) pressing an applicator against the raw wood-based material panel so that an introduction chamber forms between the applicator and the raw wood-based material panel that is sealed by a seal of the applicator, (b) pressing the liquid containing flame retardant into the introduction chamber, and (c) subsequently reducing an introduction pressure in the introduction chamber.

4. The method according to claim 3, wherein the applicator is pressed against the raw wood-based material panel from below.

5. The method according to claim 3, further comprising: (d) after reducing the introduction pressure, moving the applicator relative to the raw wood-based material panel, (e) re-pressing the applicator against the raw wood-based material panel, (f) pressing the liquid containing flame retardant into the introduction chamber, (g) reducing the introduction pressure in the introduction chamber to ambient pressure, and (h) repeating the steps above until the raw wood-based material panel is equipped with flame retardant.

6. The method according to claim 1, wherein the negative pressure is applied (a) from above, and/or; (b) by a suction cup, to a suction surface, which corresponds to a pressure surface, that the liquid containing flame retardant is pressed into.

7. The method according to claim 3, wherein (a) the applicator is moved relative to the raw wood-based material panel while the liquid containing flame retardant is being pressed in, and/or (b) the raw wood-based material panel is moved and the applicator is moved with it.

8. The method according to claim 1, wherein the negative pressure is applied in such a way that an inner concentration of flame retardant in an inner thickness quintile of a thickness expansion from the first lateral surface to the second lateral surface is at most 0.8 times an outer concentration in a first outermost thickness quintile that extends to the first lateral surface.

9. The method according to claim 1, wherein the liquid is applied in such a way that the peripheral zone of at least 90% of a lateral surface area of the wood-based material panel contains flame retardant.

10. The method according to claim 1, further comprising: (a) a concentration of flame retardant in the liquid corresponds to at least half of the solubility of the flame retardant, and/or (b) a concentration of flame retardant in the liquid is at least 50 percent by weight, and/or (c) the liquid is an aqueous solution or a suspension.

11. The method according to claim 1, wherein the liquid contains at least one coloring agent which is selected in such a way that a flame retardant content is determined from a color of the wood-based material panel in a cross-section.

12. The method according to claim 1, further comprising: (a) a liquid temperature of the liquid during application onto the first lateral surface is at least 40 C., and/or (b) a surface temperature of the first lateral surface during application of the liquid is at most 50 C.

13. The method according to claim 1, further comprising: (a) at a point where the liquid containing flame retardant is applied, the surface temperature of the first lateral surface is lower than the liquid temperature, and/or (b) at the point where the liquid containing flame retardant is applied, the concentration of flame retardant in the liquid at the surface temperature of the first lateral surface is higher than a saturation concentration of the flame retardant in the liquid.

14. The method according to claim 1, further comprising: (a) an area-specific application amount of liquid is at least 0.3 kilograms per square meter and/or at most 5 kilograms per square meter, and/or (b) the area-specific application amount of liquid is selected in such a way that a surface layer moisture level of a surface layer of the raw wood-based material panel deviates from a core moisture level by at most 30%.

15. The method according to claim 1, wherein the negative pressure is at least 300 hPa.

16. The method according to claim 1, further comprising: (a) rotating the raw wood-based material panel after the liquid has been introduced into the peripheral zone of the first lateral surface, (b) applying the liquid to the second lateral surface, and (c) applying the negative pressure to the first lateral surface so that the liquid is sucked into a peripheral zone of the second lateral surface of the raw wood-based material panel, resulting in the wood-based material panel.

17. The method according to claim 1, further comprising: (a) scattering a first surface chip layer, (b) scattering at least one middle chip layer arranged on the first surface chip layer, and (c) scattering a second surface chip layer arranged on the middle chip layer, (d) pressing the layers to form the raw wood-based material panel, which comprises: a first surface layer resulting from the first surface chip layer, a middle layer resulting from the middle chip layer, and a second surface layer resulting from the second surface chip layer, and (e) applying the liquid containing flame retardant with an area-specific application amount of liquid that corresponds to at least 10 percent by weight of an area-specific mass of the first surface layer.

18. A wood-based material panel production device comprising: (a) a press for pressing at least one primary product layer to form the raw wood-based material panel, (b) a liquid application device for applying a liquid to the raw wood-based material panel, and (c) a suction device designed to apply a negative pressure to a lateral surface of the raw wood-based material panel, (d) the liquid contains a flame retardant, (e) the suction device is designed to automatically apply the negative pressure for such a suction time that the liquid containing the flame retardant is sucked into a peripheral zone of the raw wood-based material panel but not through the raw wood-based material panel, and/or (f) the wood-based material panel production device has a pressure application device which applies an overpressure to a first lateral surface so that the liquid containing the flame retardant is pressed into the peripheral zone of the raw wood-based material panel.

19. The wood-based material panel production device according to claim (e), wherein the pressure application device is designed to apply the overpressure to a pressure surface which corresponds to at most 50% of a surface of the wood-based material panel.

20. The wood-based material panel production device according to claim (e), further comprising: (a) an applicator designed to press against the raw wood-based material panel so that an introduction chamber forms between the applicator and the raw wood-based material panel that is sealed by a seal of the applicator, and (b) a control unit configured to automatically carry out a method comprising the steps of controlling the applicator (i) so that the liquid containing flame retardant is pressed into the introduction chamber, and (ii) reducing an introduction pressure in the introduction chamber, in to ambient pressure.

21. The wood-based material panel production device according to claim 20, wherein the applicator comprises an actuator for pressing the applicator against the raw wood-based material panel.

22. The wood-based material panel production device according to claim 18, wherein the suction device is arranged for applying the negative pressure to a suction surface that corresponds to the pressure surface.

23. A wood-based material panel comprising (a) flame-retardant in accordance with specification standard DIN EN 13501-1: 2010 and test standard DIN EN 13823: 2015, in Class B comprising B-s1 or B-s1 d0, or C comprising C-s1, C-s1 d0 or B.sub.fl comprising (B.sub.fl-s1 or B.sub.fl-s1 d0, or C.sub.fl comprising C.sub.fl-s1, C.sub.fl-s1 D0, or Class B1, B2 or B3 and/or (b) has a concentration gradient of flame retardant, wherein the flame retardant concentration reduces as the distance from a surface to a center of the wood-based material panel increases.

24. The wood-based material panel according to claim 23, further comprising: (a) an inner concentration of flame retardant in an inner thickness quintile of a thickness expansion from the first lateral surface to the second lateral surface is at most 0.8 times an outer concentration in a first outermost thickness quintile that extends to the first lateral surface and/or (b) a second-decile concentration of flame retardant in the second thickness decile of the thickness expansion, which lies next to the first outermost thickness decile in the direction of a center of the thickness expansion, is at least 0.1 times a first-decile concentration in the first outermost thickness decile.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0075] In the following, the invention will be explained in more detail with the aid of the accompanying drawings. They show:

[0076] FIG. 1 is a schematic view of a wood-based material panel production device according to the invention for carrying out a method according to the invention for producing a wood-based material panel according to the invention.

[0077] FIG. 2 is a schematic cross-sectional view of a suction device of the wood-based material panel production device according to FIG. 1.

[0078] FIG. 3 in each of the partial FIGS. 3a, 3b and 3c, is a schematic cross-section through a wood-based material panel according to the invention, which has been produced according to the invention.

[0079] FIG. 4 is a section from a wood-based material panel production device according to the invention in accordance with a second embodiment.

[0080] FIG. 5 is a schematic representation of two applicators of the wood-based material panel production device according to FIG. 4.

[0081] FIG. 6 depicts in the partial FIGS. 6a and 6b two views of part of a wood-based material production device according to a third embodiment and in the partial FIG. 6c a cross-sectional view of part of a wood-based material production device according to a third embodiment.

DETAILED DESCRIPTION

[0082] FIG. 1 schematically depicts a wood-based material panel production device 10 that comprises a press 12 in the form of a continuous belt press for pressing at least one primary product layer 14, in the present case three primary product layers 14.i, to form a raw wood-based material panel 16. The at least one primary product layer 14 is created by a scattering device 18.

[0083] In the present case, the scattering device 18 comprises a first scatterer 20.1 for scattering a first primary product layer 14.1 in the form of a first surface chip layer, a second scatterer 20.2 for scattering a second primary product layer 14.2 in the form of a middle chip layer and a third scatterer 20.3 for scattering a third primary product layer 14.3 in the form of a second surface chip layer.

[0084] After being pressed by the press 12, the resulting raw wood-based material panel 16 has a first surface layer 22.1, a middle layer 22.2 and a second surface layer 22.3.

[0085] The press 12 is heated, for example, by means of a thermofluid 24, which flows in heating pipes 26.1, 26.2, . . . . The heat of the thermofluid 24 is transferred to a circulating press belt 28, which presses onto the primary product layers 14.i by means of pressure rollers 30.1, 30.2, . . .

[0086] A liquid application device 32 is arranged downstream of the press 12 in a direction of material flow M, by means of which a flame-retardant liquid 34 can be applied to a first lateral surface S1 of the raw wood-based material panel 16.

[0087] In addition, a suction device 36 is arranged downstream of the press 12 in the direction of material flow M, by means of which liquid 34 that has been applied to the first lateral surface S1 is sucked into the raw wood-based material panel 16.

[0088] The liquid application device 32 comprises a liquid reservoir 38 as well as a pump 40 by means of which the liquid 34 is guided to at least one nozzle 41 at a liquid pressure p.sub.34. The nozzle 41 generates a spray 42 that settles on the first lateral surface S1. The nozzle 41 can be part of a nozzle bar 43 that comprises three or more nozzles.

[0089] The liquid application device 32 can comprise a temperature control device 43, which keeps the liquid 34 at a given temperature T.sub.34.

[0090] FIG. 2 shows an enlarged view of the suction device 36 which comprises a vacuum table 37 with a circumferential seal 44, by means of which the second lateral surface S2 is sealed against a suction chamber 46. The suction device 36 has supports 48.j, (j=1, 2, . . . ) which brace the raw wood-based material panel 16.

[0091] The suction chamber 46 is connected to a vacuum pump 52 by means of a vacuum line 49. Preferably, a pressure p.sub.46 in the suction chamber of less than p.sub.46=500 hPa is applied to the suction chamber. As a result, the liquid 34 is sucked into a first peripheral zone 50.1 of the raw wood-based material panel. After a given suction time t.sub.saug the suction chamber is ventilated, the raw wood-based material panel 16 rotated, the pressure p.sub.46 reapplied to the suction chamber and liquid 34 applied to the second lateral surface. The suction chamber is ventilated again after the given suction time t.sub.saug.

[0092] Alternatively or in addition to the nozzle 41, the liquid application device 32 may comprise an application roller 53 or another device for applying the liquid 34 to the first lateral surface S1.

[0093] FIG. 3a schematically illustrates a cross-section through a wood-based material panel 54 according to the invention, which has a first edge surface K1 and a second edge surface K2.

[0094] FIG. 3b shows the course of the concentration CF,.sub.54 of flame retardant in the wood-based material panel 54 as a function of the distance z from the respective nearest lateral surface. It should be noted that the concentration is highest on the surface. With increasing distance z from the first lateral surface S1 of the wood-based material panel 54 the concentration decreases up to the center of the wood-based material panel 54.

[0095] In an inner thickness quintile Q3 the wood-based material panel 54 has an inner concentration CF,.sub.Q3 of flame retardant. In a first outermost thickness quintile Q1 the wood-based material panel 54 has a first outer concentration CF,.sub.Q1 of flame retardant. In a second outermost thickness quintile Q5 the wood-based material panel 54 has a second outer concentration CF,.sub.Q5.

[0096] It should be noted that the outer concentration is significantly greater than the inner concentration. In the present case, the following applies: CF,.sub.Q3=0.25.Math. CF,.sub.Q1.

[0097] FIG. 3c depicts a division into deciles. It should be noted that a second-decile concentration CF,.sub.D2 of flame retardant in the second thickness decile of the thickness expansion, which lies next to the first outermost thickness decile in the direction of a center of the thickness expansion, is at least 0.1 times a first-decile concentration CF,.sub.D1 in the first outermost thickness decile.

[0098] FIG. 4 shows a liquid application device 32 of a wood-based material panel production device 10 according to the invention that comprises a pressure application device 56 which, by means of the pump 40, introduces liquid containing flame retardant 34 from the liquid reservoir 38 into an introduction chamber 58 at an introduction pressure p.sub.e. The introduction chamber 58 is limited by a seal 60 of the pressure application device. The pressure application device 56 can be designed to apply the liquid containing flame retardant 34 from below or from above.

[0099] A negative pressure can be applied by means of the vacuum pump 52 of the suction device 36 to the raw wood-based material panel 16 via the vacuum line 49. For example, a pressure p.sub.46 in the suction chamber 46 is at most p.sub.46=700 hPa. This corresponds to a negative pressure of at least 300 hPa.

[0100] FIG. 5 schematically shows that the suction device 36 can be configured to apply a local negative pressure. In this case, a suction surface F.sub.s is smaller than the surface of the raw wood-based material panel 16. In the present case, the suction surface F.sub.s is smaller than one tenth of the surface of the raw wood-based material panel 16.

[0101] The wood-based material panel production device may also comprise a second suction device 36, which is preferably structurally identical to the first suction device 36.

[0102] A pressure surface FD, to which the pressure application device 56 applies the introduction pressure p.sub.e, largely corresponds to the suction surface F.sub.s, i.e. with a deviation of at most a factor of 2, for example, in particular at most a factor of 1.1, in particular at most a factor of 1.25.

[0103] FIG. 6a shows a positioning device 62, such as a robot, for positioning an applicator 64 and for pressing the applicator 64 against the raw wood-based material panel 16. For this purpose, the positioning device 62 has an arm 66, for example. The arm 66 may comprise 2 or more partial arms 68.1, 68.2, which can be connected to each other in an articulated manner. By means of a drive 70, the applicator 64 can be automatically positioned to a position relative to the raw wood-based material panel 16, wherein said position can be preset.

[0104] The applicator 64 is supplied by means of a flexible line 72 with a pressurized liquid 34, which is sprayed onto the raw wood-based material panel 16 and/or pressed into the raw wood-based material panel 16 under pressure.

[0105] Irrespective of the features otherwise specified for the present embodiment, the wood-based material production device 10 can comprise a suction device 36, which has a suction cup 74 that can be positioned at a given point. The suction device 36 is designed in such a way that the suction cup 74 is always positioned opposite the applicator 64. To this end, the drive 70 is controlled by a control unit 76 of the wood-based material panel production device. The suction cup 74 is connected to the vacuum pump 52 by means of a flexible vacuum line.

[0106] FIG. 6c depicts a further embodiment of a pressure application device 56 in which the liquid containing flame retardant 34 is introduced into the introduction chamber 58 by means of a nozzle 78. The introduction pressure p.sub.e can be set by means of a pressure source 80, which is connected to the introduction chamber 58 via a pressure line 82.

[0107] It is possible to move the applicator 64 and, if necessary, the suction cup 74 while an overpressure and/or negative pressure is applied. Alternatively, the pressure in the suction chamber and/or the introduction pressure is approximated to the ambient pressure before the applicator and/or the suction cup is moved, in particular completely approximated.

Embodiment Example 1

[0108] An unsanded raw wood-based material panel 16 in the form of an OSB panel with a thickness d of d=20 mm was placed on the vacuum table 37. The raw wood-based material panel 16, which had been produced with one percent PMDI binding agent (PMDI: polymeric methylenediphenyldiisocyanate) more in the surface layers 22.1, 22.3 when compared with a non-flame-retardant wood-based material panel, was treated with a solution of flame retardant Ecoaphos MK 68, 60 percent by weight from Ecoatech in an amount of 0.49 kg/m.sup.2 using a nozzle bar.

[0109] This corresponds to an amount of 15 percent by weight in relation to the area-specific weight of the top layers 22.1, 22.3. A top layer thickness of the top layers is d22.1=d.sub.22.3=3 mm1 mm. A negative pressure of 300 mbar was applied from the lower side. Within t.sub.saug=120 s15 s the liquid 34, i.e. the flame-retardant solution, had completely penetrated into the raw wood-based material panel 16.

[0110] The raw wood-based material panel 16 was rotated and the method repeated. Samples (base area: DIN A4, sample 1) were subsequently cut out of the raw wood-based material panel 16 and tested together with a conventionally produced flame-retardant OSB panel. The conventionally produced flame-retardant OSB panel had a comparable amount of the aforementioned flame retardant in the surface layer and had been air-conditioned before the test (moisture: approximately 9%). In the process, the samples were flame-treated for different lengths of time using a gas burner positioned at a defined distance from the surface. Once the flame treatment period was over, it was noted whether burning/further burning could be observed and the duration of further burning was determined.

Embodiment Example 2

[0111] An unsanded raw wood-based material panel 16 in the form of an OSB panel with a thickness d=20 mm (raw density approximately 650 kg/m.sup.3) was placed on the vacuum table 37, which was fitted with the circumferential seal 44. The raw wood-based material panel 16, which had been produced with one percent more binding agent (PMDI) in the surface layer, was treated with a solution of a flame retardant from Ecoatech (Ecoaphos MK 68, 60 percent by weight) in an amount of 0.49 kg/m.sup.2 using the nozzle bar 43. The solution of the flame retardant had been previously heated to approximately T.sub.34=60 C. to facilitate penetration.

[0112] The amount of liquid corresponds to an amount of 15 percent by weight in terms of the surface layer strand (thickness of the surface layer approximately 3 mm per side). A vacuum of 150 mbar was applied from the lower side. After a suction time of t.sub.saug=90 seconds the flame-retardant solution had completely penetrated into the raw wood-based material panel 16. The raw wood-based material panel 16 was rotated and the method repeated.

[0113] 16 samples (DIN A4, sample 2) were subsequently also cut out of this raw wood-based material panel 16 and likewise tested for flammability in accordance with DIN EN 13823:2015 together with a conventionally produced flame-retardant OSB panel.

[0114] The conventionally produced OSB panel had a comparable amount of the aforementioned flame retardant in the surface layer and had been air-conditioned before the test (moisture: approximately 9%).

[0115] When testing for flammability, the samples were flame-treated for different lengths of time according to the left-hand column of the following table using a gas burner positioned at a defined distance from the surface. Once the flame treatment period was over, it was noted whether burning/further burning and the duration of further burning could be observed.

TABLE-US-00001 TABLE 1 Observations following flame treatment Reference Duration (conventionally of flame manufactured treatment OSB) Sample 1 Sample 2 2 min No further No further No further burning burning burning 4 min No further No further No further burning burning burning 8 min No further No further No further burning burning burning 12 min No further No further No further burning burning burning 15 min No further No further No further burning burning burning

[0116] As can be seen from the flame treatment trials, wood-based material panels produced using a method according to the invention perform just as well as the reference panel. Even after 15 minutes of flame treatment, none of the samples exhibited further burning after the burner had been deactivated. The subsequent examination showed that the wood-based material panels produced according to the invention exhibited an even higher strength after testing. In the case of the reference panel, individual charred strands could be easily removed from the structure mechanically, which was only possible with greater effort in the case of the two wood-based material panels produced according to the invention.

Embodiment Example 3

[0117] An unsanded raw wood-based material panel 16 in the form of an HDF panel with a thickness d=8 mm (raw density approximately 850 kg/m.sup.3) was placed on the vacuum table 37, which was fitted with the circumferential seal 44. The raw wood-based material panel 16, which had been produced with one percent more binding agent based on a urea-formaldehyde adhesive, was treated with a solution of a flame retardant from Ecoatech (Ecoaphos MK 68, 50 percent by weight) in an amount of 0.31 kg/m.sup.2 using the nozzle bar 43. The proportion of binding agent was also increased in this panel (2% more than the standard). The solution of the flame retardant had been previously heated to approximately T.sub.34=60 C. to facilitate penetration.

[0118] Via the liquid, an amount of flame retardant was introduced into the wood-based material panel that constituted 15 percent by weight in relation to the surface layer (thickness of the surface layer approximately 1.2 mm per side). A vacuum of 150 mbar was applied from the lower side. After a suction time of t.sub.saug=120 seconds the flame-retardant solution had completely penetrated into the raw wood-based material panel 16. The raw wood-based material panel 16 was rotated and the method repeated.

[0119] 16 samples (DIN A4, sample 2) were subsequently cut out of this wood-based material panel 16 and tested for flammability in accordance with DIN EN 13823:2015 together with a conventionally produced flame-retardant HDF panel.

[0120] The conventionally produced wood-based material panel had a comparable amount of the aforementioned flame retardant in the panel and had been air-conditioned before the test (moisture: approximately 9%).

[0121] When testing for flammability, the samples were tested in exactly the same way as the OSB. The results in terms of flammability and strength after the fire test were comparable to those of the OSB test.

Embodiment Example 4

[0122] The steps carried out for embodiment 3 were carried out for an unsanded raw wood-based material panel 16 in the form of an MDF panel with a thickness d=8 mm (raw density approximately 750 kg/m.sup.3).

[0123] When testing for flammability, the samples were tested in exactly the same way as a conventionally produced MDF panel. The MDF panel produced according to the invention achieved or exceeded the results in terms of flammability and strength when compared to the conventionally produced MDF panel.

Embodiment Example 5

[0124] The steps carried out for embodiment 3 were carried out for an unsanded raw wood-based material panel 16 in the form of a chipboard with a thickness d=8 mm (raw density approximately 650 kg/m.sup.3).

[0125] When testing for flammability, the samples were tested in exactly the same way as a conventionally produced chipboard. The chipboard produced according to the invention achieved or exceeded the results in terms of flammability and strength when compared to the conventionally produced chipboard.

Embodiment Example 6

[0126] The steps carried out for embodiment 3 were carried out for an unsanded raw wood-based material panel 16 in the form of insulating board with a thickness d=20 mm (raw density approximately 250 kg/m.sup.3).

[0127] When testing for flammability, the samples were tested in exactly the same way as a conventionally produced insulating board. The insulating board produced according to the invention achieved or exceeded the results in terms of flammability and strength when compared to the conventionally produced insulating board.