Method for treating a panel of wood-based material and building panel with a core of wood-based material

Abstract

A method for treating a panel of wood-based material to achieve an adhesive-free surface after a decoration (2) has been printed onto at least an upper side of the panel of wood-based material, is distinguished by the fact that a cellulose-free top layer (3) of melamine resin with mixed-in glass beads (5) is applied to the decoration (2), and this top layer (8) is dried before a wear-resistant layer (6) is applied to the top layer (8).

Claims

1. A method for treating a woodbase material board in order to achieve a tack-free surface following printing of a decoration onto at least one top face of the woodbase material board, comprising applying to the decoration a cellulose-free outer layer of melamine resin into which glass beads have been mixed, drying the outer layer resulting in the tack-free surface at an intermediate stage of production, and applying an antiwear layer to the outer layer, wherein the drying is performed prior to the applying of the antiwear layer.

2. The method as claimed in claim 1, further comprising actively drying the outer layer.

3. The method as claimed in claim 1, wherein the glass beads are used in silanized form.

4. The method as claimed in claim 1, further comprising applying the melamine resin/glass bead mixture in an amount of 10 to 30 g/m.sup.2.

5. The method as claimed in claim 1, further comprising applying the melamine resin/glass bead mixture in an amount of 12 to 20 g/m.sup.2.

6. The method as claimed in claim 1, wherein a fraction of glass beads in the mixture is 12 to 16 wt %.

7. The method as claimed in claim 6, wherein a diameter of the glass beads is in a range from 60 to 90 μm.

8. The method as claimed in claim 6, wherein a diameter of the glass beads is in a range from 70 to 110 μm.

9. The method as claimed in claim 1, further comprising applying a primer layer composed of 15 to 40 g/m.sup.2 of an aqueous melamine resin to the top face of the woodbase material board.

10. The method as claimed in claim 9, wherein the woodbase material board is a woodbase material/plastic mixture.

11. The method as claimed in claim 9, further comprising applying a base of an aqueous paint to the primer layer.

12. The method as claimed in claim 11, wherein the base is a white base having a application of 20 to 30 g/m.sup.2 of the aqueous white paint.

13. The method as claimed in claim 11, wherein the decoration consists of a plurality of successively applied decorative prints.

14. The method as claimed in claim 13, wherein the decorative prints is applied by offset printing or a digital printing.

15. The method as claimed in claim 13, wherein the outer layer consists of an aqueous melamine resin/glass bead mixture with an application quantity of 10 to 30 g/m.sup.2.

16. The method as claimed in claim 15, wherein the glass beads are mixed into the resin have a diameter of 60 to 110 μm.

17. A method for treating a woodbase material board in order to achieve a tack-free surface following printing of a decoration onto at least one top face of the woodbase material board, comprising applying to the decoration a cellulose-free outer layer of melamine resin into which glass beads have been mixed, drying the outer layer, applying an antiwear layer to the outer layer, applying a primer layer composed of 15 to 40 g/m.sup.2 of an aqueous melamine resin to the top face of the woodbase material board and applying a base of an aqueous paint to the primer layer, wherein: the drying is performed prior to the applying of the antiwear layer, the decoration consists of a plurality of successively applied decorative prints, the outer layer consists of an aqueous melamine resin/glass bead mixture with an application quantity of 10 to 30 g/m.sup.2, the glass beads are mixed into the resin have a diameter of 60 to 110 μm, and the drying of the outer layer is actively drying the outer layer, and the antiwear layer is composed of a melamine resin/corundum/cellulose fiber mixture applied in an amount of 30 to 50 g/m.sup.2.

18. The method as claimed in claim 17, further comprising pressing the woodbase material board in a short-cycle press to form woodbase material panels.

19. The method of claim 18, further comprising stacking up to 1000 woodbase material panels one on top of another without them sticking to one another.

20. The method of claim 19, wherein the stack is stored preferably at 25° C. and at atmospheric humidity of 40% to 60%.

21. The method of claim 19, further comprising destacking of the stack at 35° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A drawing is used to describe in more detail one exemplary embodiment of the invention hereinbelow.

(2) In the drawing

(3) FIG. 1 shows a diagrammatic cross section through a woodbase material board;

(4) FIG. 2 shows the detail II of FIG. 1.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

(5) The coating of the woodbase material board is to be described hereinbelow with reference to FIG. 1.

(6) A primer layer 2 composed of 15 to 40 g/m.sup.2 of an aqueous melamine resin is applied first of all to the top face of the core 1, which consists of wood fibers, of woodchips, or of a woodbase material/plastic mixture. Applied atop this primer layer 2 then, as a further print base layer, is a white base 3, by application of 20 to 30 g/m.sup.2 of an aqueous white paint. The decoration 7 consists of a plurality of—preferably two, three, or four—successively applied decorative prints, which are applied, for example, by offset printing or by means of a digital printer (inkjet printer). The outer layer 8 consists of an aqueous melamine resin/glass bead mixture, with an application quantity of 10 to 30 g/m.sup.2. The melamine resin is preferably a melamine/formaldehyde resin, and the glass beads 5 which are mixed into the resin have a diameter of 60 to 90 μm or of 70 to 110 μm. The diameter range may of course also be from 60 to 110 μm. After the outer layer 8 has been actively dried, in a subsequent coating step an antiwear layer 4 composed of a melamine resin/corundum/cellulose fiber mixture is applied in an amount of 30 to 50 g/m.sup.2. After the drying of this final coating, the woodbase material board is pressed in a short-cycle press with exposure to a high pressure and a high temperature. This woodbase material board can then be divided up, in further processing steps, into panels, and a tongue/groove profiling can then be machined into the side edges of these panels. Tongue and groove can be provided with integrated locking means and latching means, in order to allow the panels to be laid subsequently without glue.

(7) In experiments it has been found that with a melamine resin/glass bead mixture, a substantially greater amount, namely 10 to 30 g/m.sup.2, preferably 12 to 20 g/m.sup.2, can be applied than using a conventional melamine resin/cellulose mixture. Different abrasion classes AC are distinguished according to DIN EN 13329. AC3 requires at least 2000 revolutions, and AC4 at least 4000 revolutions. The experimental procedures below gave the following results:

(8) Experimental Procedure 1 “AC3”

(9) Resin mixture application of 12 g/m.sup.2 containing 12 wt % of glass with specification of 60 to 90 μm, resulting in abrasion of 2400 revolutions Resin mixture application of 16 g/m.sup.2 containing 12 wt % of glass with specification of 60 to 90 μm, resulting in abrasion of 2600 revolutions Resin mixture application of 20 g/m.sup.2 containing 12 wt % of glass with specification of 60 to 90 μm, resulting in abrasion of 2800 revolutions
Experimental Procedure 2 “AC4” Resin mixture application of 12 g/m.sup.2 containing 12 wt % of glass with specification of 70 to 110 μm, resulting in abrasion of 4200 revolutions Resin mixture application of 16 g/m.sup.2 containing 14 wt % of glass with specification of 70 to 110 μm, resulting in abrasion of 4400 revolutions Resin mixture application of 20 g/m.sup.2 containing 16 wt % of glass with specification of 70 to 110 μm, resulting in abrasion of 4600 revolutions

(10) The conditions prevailing during the application of the outer layer 8 were as follows: Line speed 60 to 100 m/min. In order to keep the operation constant, the manufacturing hall was air-conditioned and the paint line was temperature-conditioned. Furthermore, metering and monitoring took place automatically.

(11) As the experiments described above have shown, there was a greater abrasion resistance relative to conventionally coated boards, with an improvement in the micro-scratch resistance, and the chemical incorporation of the glass into the melamine resin resulted in a uniform areal distribution, which also resulted in an improved surface density against impact load. All in all, therefore, the implementation of the method of the invention leads to a simple and reliable regime of the manufacturing operation and also, in the end product, to an improvement in the robustness of the surface, and hence to improved service properties on the part of the construction board.

(12) Within the coating operation, not only is the decoration 7 sealed, but it is also possible to stack up to 1000 panels one on top of another without them sticking to one another. It has emerged that stacks of this kind can be stored for up to 180 days and that destacking is possible even at 35° C. The degree of condensation is not measurable. The stack is stored preferably at 25° C. and at atmospheric humidity of 40% to 60%. The improved transparency relative to that with cellulose, a more sharply defined decorative print, and improved colors in the decoration are fully manifested as a result of the melamine/glass bead mixture, not least because the resulting surface is uniformly impervious.