Method for producing an abrasion-resistant wood board

Abstract

A method for producing an abrasion-resistant wood-based panel having a top side and a bottom side, with at least one decorative layer arranged on the top side, in particular with a structure synchronous with the decoration, is disclosed herein.

Claims

1. A method for producing an abrasion-resistant wood-based panel with an upper side and a bottom side, with at least one decorative layer arranged on the top side, the method comprising the steps of: applying at least one first resin layer to the at least one decorative layer on the upper side of the wood-based panel, wherein the first resin layer has a solids content of between 60 and 80% by weight; even scattering of abrasion-resistant particles on the at least one first resin layer on the upper side of the wood-based panel; applying at least one second resin layer to the at least one first resin layer provided with the abrasion-resistant particles on the upper side of the wood-based panel, the second resin layer having a solids content of between 60 and 80% by weight; subsequent drying of the structure consisting of the at least one first resin layer and the at least one second resin layer in at least one drying device; applying at least a third resin layer, wherein the third resin layer has a solids content between 60 and 80% by weight, and contains glass beads; subsequent drying of the applied at least one third resin layer in at least one further drying device; applying at least one fourth resin layer, wherein the fourth resin layer has a solids content of between 50 and 70% by weight, and contains glass beads; subsequent drying of the applied at least one fourth resin layer in at least one further drying device; applying at least a fifth resin layer, wherein the fifth resin layer has a solids content of between 50 and 70% by weight, and contains glass beads; subsequent drying of the applied at least one fifth resin layer in at least one further drying device; applying at least one sixth resin layer, wherein the sixth resin layer has a solids content of between 50 and 70% by weight and does not contain glass beads; subsequent drying of the applied at least one sixth resin layer in at least one further drying device; and pressing of the layer structure in a short-cycle press, wherein the at least one first resin layer on the upper side of the wood-based panel with the abrasion-resistant particles is not dried after application.

2. The method according to claim 1, wherein the wood-based panel provided with the decorative layer is not heated in a dryer before the application of the at least one first resin layer.

3. The method according to claim 1, wherein the resin layers are based on aqueous formaldehyde-containing resins.

4. The method according to claim 1, wherein the at least one first resin layer contains cellulose fibres or wood fibres.

5. The method according to claim 1, wherein the amount of scattered abrasion-resistant particles is 10 to 50 g/m.sup.2.

6. The method according to claim 1, wherein the at least one second resin layer to be applied to the upper side of the wood-based panel does not contain glass beads.

7. The method according to claim 1, wherein the glass beads have a diameter of 90 to 150 μm.

8. The method according to claim 1, wherein the total thickness of the applied resin layers is between 60 and 200 μm.

9. The method according to claim 1, wherein the addition of a hardener to the respective resin to be applied is only carried out at the respective application device for the resin.

10. The method according to claim 1, wherein the drying of the resin layers takes place at dryer temperatures between 150 and 220° C. in a convection dryer.

11. The method according to claim 1, wherein the pressing of the layered structure is carried out under the influence of pressure and temperature in the short-cycle press at temperatures between 150 and 250° C. and at a pressure between 30 and 60 kg/cm.sup.2.

12. The method according to claim 1, wherein the coated wood-based panel is aligned in the short-cycle press to a structured press plate located in the short-cycle press by means of markings on the wood-based panel and a congruence is established between the decoration on the wood-based panel and the structure of the press plate to be embossed.

13. A wood-based panel made according to the method of claim 1, comprising a layer structure, when viewed from bottom to top, the layer structure comprises: a backing layer of six resin layers; a wood-based panel; a primer layer; a print decoration layer; a first resin layer with cellulose fibers; a layer of abrasion-resistant particles; a second resin layer; a third resin layer with glass beads; a fourth resin layer with glass beads; a fifth resin layer with glass beads; and a sixth resin layer without glass beads; wherein the layer structure has a total layer thickness between 120 and 200 μm.

14. The method according to claim 3, wherein the resin layers are based on melamine formaldehyde resin, urea formaldehyde resin, or melamine urea formaldehyde resin.

15. The method according to claim 5, wherein the amount of scattered abrasion-resistant particles is 10 to 30 g/m.sup.2.

16. The method according to claim 15, wherein the amount of scattered abrasion-resistant particles is 15 to 25 g/m.sup.2.

17. The method according to claim 8, wherein the total thickness of the applied resin layers is between 90 and 150 μm.

18. The method according to claim 17, wherein the total thickness of the applied resin layers is between 100 and 120 μm.

19. The method according to claim 10, wherein the drying of the resin layers takes place at dryer temperatures between 180 and 210° C.

20. The method according to claim 11, wherein the temperatures in the short-cycle press are between 180 and 230° C.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The solution is explained in more detail below with reference to the figures in the drawings, using an example of an embodiment.

(2) FIG. 1 shows a schematic representation of a production line of a wood-based panel using the method according to the proposed solution.

DETAILED DESCRIPTION OF THE INVENTION

(3) The production line shown schematically in FIG. 1 includes an IR dryer 1a which is switched off. Removal of the IR dryer 1a from the production line avoids the electrostatic charging of the plate surface that would otherwise take place in the IR dryer, which makes it possible to form a homogeneous scattering curtain of corundum.

(4) The production line further comprises a single-sided applicator unit 1 (grooved roller), and five double applicator units 2, 3, 4, 5, 6 for simultaneous application of the respective resin layer to the upper side and the lower side of the separated printed material boards, e.g. of printed HDF boards, as well as four convection dryers 2a, 3a, 4a, 5a, 6a arranged behind each of the applicator units in the processing direction.

(5) Downstream of the first applicator roll 1, a first scattering device 20 is provided for uniformly scattering the abrasion-resistant material such as corundum onto the first resin layer on the top side of the HDF board. The abrasion resistant material used is F200 corundum, which measures about 53-75 μm in diameter according to FEPA standards. The scattering device 20 essentially consists of a supply hopper, a rotating, structured spiked roller and a scraper. The application rate of the material is determined by the rotational speed of the scattering roller. Depending on the required abrasion class of the product, between 12-25 g/m.sup.2 of corundum is scattered onto the resin-coated board (AC4 (according to EN 13329)=20 g/m.sup.2). From the spiked roller, the corundum falls onto the melamine resin treated board at a distance of 5 cm. Since the first resin layer is still liquid at the time of scattering, the abrasion-resistant particles can sink into the resin layer. Under the present scattering device, at least one hopper (not shown) is provided in front of the scattering roller for collecting excess abrasion-resistant particles (i.e., abrasion-resistant particles not scattered on the at least one wood-based panel, but rather falling down in front of the wood-based panel before the wood-based panel is moved in by means of the transport device under the scattering roller).

(6) In the double-sided coating unit 2, the board coated with melamine-formaldehyde resin and corundum is coated with further melamine-formaldehyde resin (about 20 g/m.sup.2). At the same time, the unattached corundum is removed in small amounts and accumulates in the melamine resin liquor until saturation (about 10 wt. %) occurs. This lost portion of the corundum is now continuously reapplied to the board by the roller application of coating unit 1-1. The second application covers the corundum grains with liquid resin or incorporates them into the overlay layer. This prevents the corundum from being removed in the convection dryer due to the high air turbulence.

(7) The build-up of first and second resin layers is dried in convection dryer 2a.

(8) Downstream of the third double coater 3 for applying the third resin layer, there may be another scattering device 20 for applying glass beads to the third resin layer followed by a third convection dryer 3a for drying the third resin layer. The scattering device 20 for the glass beads is optional. The glass beads may also be applied together with the third resin layer.

(9) After application of the fourth to sixth resin layers in a fourth to sixth double coater 4, 5, 6 and drying in a convection dryer 4a, 5a, 6a respectively, the layer structure is cured in a short-cycle press 7 at a pressing temperature of 180-220° C. and a pressing time of 8 to 10 seconds under a specific pressure of 40 kg/cm.sup.2. The pressed sheets are cooled and stored.

(10) While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.