Method for producing an abrasion-resistant wood material panel and production line therefor

Abstract

The invention relates to a method for producing an abrasion-resistant wood material panel that has a decorative layer, including the following steps: applying one first resin layer to the decorative layer on the top and bottom sides of the wood material panel, scattering abrasion-resistant particles onto the resin layer on the top side of the panel; drying the resin layer provided with abrasion-resistant particles onto the first resin layers on the top and bottom sides of the panel in a drying device; applying another resin layer to the dried resin layers on both sides of the panel; drying the second resin layers on both sides of the panel in the drying device; and pressing the layer structure. The invention further relates to a production line for carrying out the method and to a wood material panel that can be produced by means of the method.

Claims

1. A process for the production of an abrasion-resistant wood-composite panel which has, on an upper side, at least one decorative layer comprising: applying at least one first resin layer to the at least one decorative layer on the upper side and to an underside of the wood-composite panel; uniformly scattering abrasion-resistant particles onto the first resin layer on the upper side of the wood-composite panel; in at least one drying device, drying of the first resin layer to which the abrasion-resistant particles have been provided on the upper side and of the first resin layer on the underside of the wood-composite panel; applying at least one second resin layer onto the dried first resin layer to which the abrasion-resistant particles have been provided on the upper side and onto the dried first resin layer on the underside, of the wood-composite panel; in at least one drying device, drying of the respective second resin layer on the upper side and the underside of the wood-composite panel; applying at least one third resin layer to the upper side and the underside of the wood-composite panel, wherein the resin applied as the third resin layer to the upper side of the wood-composite panel contains glass beads; in at least one drying device, drying the third resin layer applied to the upper side and underside of the wood-composite panel; applying at least one fourth resin layer to the upper side and the underside of the wood-composite panel, wherein the resin applied as the fourth resin layer to the upper side of the wood-composite panel contains glass beads and/or fibres; in at least one drying device, drying the fourth resin layer applied to the upper side and underside of the wood-composite panel; and pressing of the layer structure.

2. The process as claimed in claim 1, wherein the abrasion-resistant particles comprise particles made of corundum (aluminum oxide), boron carbide, silicon dioxide, and/or silicon carbide.

3. The process as claimed in claim 1, wherein a quantity of scattered abrasion-resistant particles is from 10 to 50 g/m.sup.2.

4. The process as claimed in claim 1, wherein glass beads are scattered onto the third resin layer applied on the upper side of the wood-composite panel.

5. The process as claimed in claim 1, wherein the at least one decorative layer comprises a printed decorative effect.

6. The process as claimed in claim 3, wherein the quantity of scattered abrasion-resistant particles is from 10 to 30 g/m.sup.2.

7. The process as claimed in claim 3, wherein the quantity of scattered abrasion-resistant particles is from 15 to 25 g/m.sup.2.

8. The process as claimed in claim 1, wherein an amount of the first resin layer applied to the upper side of the wood-composite panel is between 50-100 g/m.sup.2.

9. The process as claimed in claim 1, wherein an amount of the second resin layer applied to the upper surface of the wood-based panel is between 10-50 g/m.sup.2.

10. The process as claimed in claim 1, wherein an amount of the third resin layer applied to the upper surface of the wood-based panel is between 10-40 g/m.sup.2 and a solids content of the third resin layer is 50-80 wt %.

11. The process as claimed in claim 1, wherein an amount of glass beads contained in the third resin layer is 1-5 g/m.sup.2.

12. The process as claimed in claim 1, wherein the fourth resin layer contains wood fibres or cellulose fibres.

13. The process as claimed in claim 1, wherein an amount of the fourth resin layer applied to the upper side of the wood-based panel is between 10-40 g/m.sup.2 and a solids content of the fourth resin layer is 50-80 wt %.

14. The process as claimed in claim 1, wherein an amount of glass beads contained in the fourth resin layer is 1-5 g/m.sup.2.

15. The process as claimed in claim 1, wherein an amount of fibres contained in the fourth resin layer is 0.1-0.5 g/m.sup.2.

16. The process as claimed in claim 1, further comprising providing a scattering device for scattering the abrasion-resistant particles and a light barrier, wherein the light barrier initiates the scattering device when a panel is located below the scattering device.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention is explained in more detail below by describing an embodiment, with reference to the figures in the drawings, where

(2) FIG. 1 is a diagram of a production line for a wood-composite panel, using the process of the invention.

DESCRIPTION OF THE INVENTION

(3) The production line presented diagrammatically in FIG. 1 comprises four double-applicator assemblies 1, 2, 3, 4 for the simultaneous application of the respective resin layer on the upper side and the underside of the unitized printed panels, e.g. of printed HDF panels, and also respectively four convection dryers la, 2a, 3a, 4a arranged behind the double-applicator assemblies in the direction of processing.

(4) After the first applicator roll 1, there is moreover a first scattering device 10 provided for the uniform scattering of the abrasion-resistant material, e.g. corundum, onto the first resin layer on the upper side of the HDF panel. The first resin layer is then dried in the first convection dryer 1a.

(5) This is followed by a second double-applicator unit 2 for the application of the second resin layer, and by a second convection dryer 2a for the drying of the second resin layer.

(6) Downstream of the third double-applicator unit 3 for the application of the third resin layer, there can be a further scattering device 20 for the application of glass beads to the third resin layer, followed by a third convection dryer 3a for the drying of the third resin layer. The scattering device 20 for the glass beads is optional. The glass beads can also be applied together with the third resin layer.

(7) After application of the fourth resin layer, which in the case of the fourth resin layer on the upper side can for example comprise cellulose fibers, in a fourth double-applicator unit 4 and drying in a fourth convection dryer 4a, the layer structure is pressed in a short-cycle press 5. The pressed panels are cooled and stored.

Embodiment 1

(8) A stack of printed HDF (dark wood decorative effect) is unitized before the production line and is transported through the line at a velocity of 28 m/min.

(9) In a first roll-applicator assembly, about 70 g of liquid melamine resin (solids content: 55% by weight) comprising the conventional auxiliaries (hardeners, wetting agents, etc.) are applied to the panel surface. The first roll-applicator assembly likewise applies a melamine resin to the panel underside (quantity applied: 60 g of liquid resin/m.sup.2, solids content: about 55% by weight).

(10) A scattering apparatus is then used to scatter 14 g of corundum/m.sup.2 (F200) onto the surface. A distance of about 5 m before the dryer is reached allows the corundum to sink into the melamine resin. The panel then passes through a convection dryer. A quantity of 25 g/m.sup.2 of the melamine resin layer (solids content: 55% by weight) is then applied. Again, this comprises the conventional auxiliaries. A roll-applicator assembly is likewise used to apply a melamine resin to the panel underside (quantity applied: 50 g of liquid resin/m.sup.2, solids content: about 55% by weight). Again, the panel is dried in a convection dryer.

(11) A melamine resin that additionally also comprises glass beads is then applied to the panel surface. The diameter of the beads is from 60 to 80 μm. The quantity applied of the resin is about 20 g of liquid melamine resin/m.sup.2 (solids content: 61.5% by weight). The formulation also comprises a release agent, alongside the curing agent and the wetting agent. The quantity of glass beads applied is about 3 g/m.sup.2. A roll-applicator assembly is likewise used to apply a melamine resin to the panel underside (quantity applied: 40 g of liquid resin/m.sup.2, solids content: about 55% by weight). Again, the panel is dried in a convection dryer, and is then again coated with a melamine resin comprising glass beads. Cellulose (Vivapur 302) is present as further component. Again, about 20 g of liquid melamine resin/m.sup.2 (solids content: 61.6% by weight) are applied. Here again, about 3 g of glass beads and 0.25 g of cellulose/m.sup.2 are applied. The formulations also comprise a release agent, alongside the curing agent and the wetting agent. A roll-applicator assembly is likewise used to apply a melamine resin to the panel underside (quantity applied: 30 g of liquid resin/m.sup.2, solids content: about 55% by weight). Again, the resin is dried in a convection dryer, and then the panel is pressed with a pressure of 400 N/cm.sup.2 in a short-cycle press at 200° C. Press time was 10 seconds. Structure was provided by using a press platen with a wood structure.

(12) For comparison, a panel with corundum applied by way of a roll applicator was pressed. The quantities of resin applied were at the same level as in the case of the scattered-corundum panel. Applicator units 1 to 2 here comprised corundum-containing formulations. In the final applicator units, the resins comprised glass beads or glass beads and cellulose. The quantity of corundum applied was determined gravimetrically as about 20 g/m.sup.2. The performance of both samples in relation to abrasion was determined in accordance with DIN EN 15468. The transparency of the surface was assessed visually. The values obtained here were as follows:

(13) TABLE-US-00001 Sample Scattered Corundum from Test corundum roll applicator Performance in 4200/4400 Um. 4000/4100 Um. relation to abrasion (DIN EN 15468) (two determinations) Transparency Good Slight transparency transparency problems in wood pores

Embodiment 2

(14) A stack of printed HDF (dark wood decorative effect) is unitized before the production line and is transported through the line at a velocity of 28 m/min.

(15) In a first roll-applicator assembly, about 70 g of liquid melamine resin (solids content: 55% by weight) comprising the conventional auxiliaries (hardeners, wetting agents, etc.) are applied to the panel surface. The first roll-applicator assembly likewise applies a melamine resin to the panel underside (quantity applied: 60 g of liquid resin/m.sup.2, solids content: about 55% by weight).

(16) A scattering apparatus is then used to scatter 23 g of corundum/m.sup.2 (F200) onto the surface. A distance of about 5 m before the dryer is reached allows the corundum to sink into the melamine resin. The panel then passes through a convection dryer.

(17) A quantity of 25 g/m.sup.2 of a second melamine resin layer (solids content: 55% by weight) is then applied. Again, this comprises the conventional auxiliaries. A roll-applicator assembly is likewise used to apply a second melamine resin to the panel underside (quantity applied: 50 g of liquid resin/m.sup.2, solids content: about 55% by weight). Again, the panel is dried in a convection dryer.

(18) Following the drying process, again a third melamine resin is applied by a roll assembly. The quantity applied of the resin is about 20 g of liquid melamine resin/m.sup.2 (solids content: 61.5% by weight). The formulation also comprises a release agent, alongside the hardener and the wetting agent. A roll-applicator assembly is likewise used to apply a third melamine resin to the panel underside (quantity applied: 40 g of liquid resin/m.sup.2, solids content: about 55% by weight). A scattering assembly is then used to scatter about 6 g of glass beads/m.sup.2. The diameter of these was from 60 to 80 μm. Again, the panel is dried in a convection dryer and then again coated with a fourth melamine resin, which comprises cellulose (Vivapur 302). Again, about 20 g of liquid melamine resin/m.sup.2 (solids content: 56.0% by weight) are applied. 0.25 g of cellulose/m.sup.2 is applied here. A roll-applicator assembly is likewise used to apply a fourth melamine resin to the panel underside (quantity applied: 30 g of liquid resin/m.sup.2, solids content: about 55% by weight). The formulations also comprise a release agent, alongside the hardener and the wetting agent. Again, the resin is dried in a convection dryer, and the panel is then pressed with a pressure of 400 N/cm.sup.2 in a short-cycle press at 200° C. Press time is 10 seconds. Structure was provided by using a press platen with a wood structure.

(19) For comparison, a panel with corundum applied by way of a roll applicator was pressed. The quantities of resin applied in the case of this panel were about 20 g/m.sup.2 (solid) higher than for the scattered-corundum panel. Corundum-containing formulations were used in the first three applicator units here. In the final applicator unit, the melamine resin comprised glass beads and cellulose. The quantities applied of the two components were comparable with those for the scattered panel. The quantity of corundum applied was determined gravimetrically as about 30 g/m.sup.2. The performance of both samples in relation to abrasion was determined in accordance with DIN EN 15468. The transparency of the surface was assessed visually. The values obtained here were as follows:

(20) TABLE-US-00002 Sample Scattered Corundum from Test corundum roll applicator Performance in 6300/6500 Um. 6200/5950 Um. relation to abrasion (DIN EN 15468) (two determinations) Transparency Good Greater transparency transparency problems in wood pores and across the entire surface

Embodiment 3

(21) In a large-scale trial, 10 000 printed HDF panels (format: 5600×2070 mm dark wood decorative effect) were unitized for the production line and transported through the line at a velocity of 28 m/min.

(22) In a first roll-applicator assembly, about 70 g of liquid melamine resin (solids content: 55% by weight) comprising the conventional auxiliaries (hardeners, wetting agents, etc.) are applied to the panel surface. A roll-applicator assembly likewise applies a melamine resin to the panel underside (quantity applied: 60 g of liquid resin/m.sup.2, solids content: about 55% by weight).

(23) A scattering apparatus is then used to scatter 23 g of corundum/m.sup.2 (F200) onto the surface. A distance of about 5 m before the dryer is reached allows the corundum to sink into the melamine resin. The panel then passes through a convection dryer.

(24) A quantity of 25 g/m.sup.2 of a second melamine resin layer (solids content: 55% by weight) is then applied. Again, this comprises the conventional auxiliaries. A roll-applicator assembly is likewise used to apply a second melamine resin to the panel underside (quantity applied: 50 g of liquid resin/m.sup.2, solids content: about 55% by weight). Again, the panel is dried in a convection dryer.

(25) Following the drying process, again melamine resin is applied by a roll assembly. The quantity applied of the resin is about 20 g of liquid melamine resin/m.sup.2 (solids content: 61.5% by weight). The formulation also comprises a release agent, alongside the hardener and the wetting agent. A roll-applicator assembly is likewise used to apply a melamine resin to the panel underside (quantity applied: 40 g of liquid resin/m.sup.2, solids content: about 55% by weight). A scattering assembly is then used to scatter about 6 g of glass beads/m.sup.2. The diameter of these was from 60 to 80 μm. Again, the panel is dried in a convection dryer and then again coated with melamine resin, which comprises cellulose (Vivapur 302). Again, about 20 g of liquid melamine resin/m.sup.2 (solids content: 56.0% by weight) are applied. 0.25 g of cellulose/m.sup.2 is applied here. A roll-applicator assembly is likewise used to apply a melamine resin to the panel underside (quantity applied: 30 g of liquid resin/m.sup.2, solids content: about 55% by weight). The formulations also comprise a release agent, alongside the hardener and the wetting agent. Again, the resin is dried in a convection dryer, and the panel is then pressed with a pressure of 400 N/cm.sup.2 in a short-cycle press at 200° C. Press time is 10 seconds. Structure was provided by using a press platen with a wood structure.

(26) For comparison, 10 000 panels with corundum applied by way of a roll applicator were pressed. The quantities of resin applied in the case of these panels were about 20 g/m.sup.2 (solid) higher than for the scattered-corundum panel. Corundum-containing formulations were used in the first three applicator units here. In the final applicator unit, the melamine resin comprised glass beads and cellulose. The quantities applied of the two components were comparable with those for the scattered panel. The quantity of corundum applied was determined gravimetrically as about 30 g/m.sup.2. The performance of both samples in relation to abrasion was determined in accordance with DIN EN 15468. The transparency of the surface was assessed visually. The values obtained here were as follows:

(27) TABLE-US-00003 Scattered Corundum from corundum roll applicator Sample (after 10 000 (after 10 000 Test pressings) pressings) Gloss level change*) −1 gloss −4 gloss points measured point (Initial value: 15 gloss points) Visual assessment of No noticeable Clearly visible gloss level change change wear at the corners of the press platens *)Gloss level was measured with a gloss level tester from Dr. Lange at a measurement angle of 60°, DIN EN 13 722: 2004-10