EP3246175B1 - Method of producing an abrasion resistant wooden panel and production line for same - Google Patents

Description

The present invention relates to a method for producing an abrasion-resistant wood-based panel according to the preamble of claim 1, a production line for carrying out this method according to claim 12 and a wood-based panel according to claim 14.

description

A variety of products or product surfaces which are subject to mechanical wear and tear must be protected by the application of wear-resistant coatings, from premature damage or destruction by wear. These products may, for. B. to furniture, interior panels, floors, etc. act. Depending on the frequency and intensity of the load, different protective measures have to be applied so that the user can be guaranteed the longest possible service life.

Many of the above products have decorative surfaces that quickly become unsightly when worn due to heavy use and / or are no longer cleanable. These decorative surfaces are very often made of impregnated with thermosetting resins papers that are pressed in so-called short-cycle presses on the wood material carrier used. As a thermosetting resin melamine-formaldehyde resin is very often used.

As a protection for the decorative surfaces so-called overlay papers have been used for a long time, which are thin, α-cellulose-containing papers. These have after impregnation with melamine-formaldehyde resins and Mitverpressung on the decorative papers a high transparency, so that the brilliance of the decor is not or only slightly affected.

However, the improvement in wear resistance by these overlay papers is not sufficient in all cases. For a kitchen countertop or countertop, the overlay solutions were adequate, but they are not for heavier areas or even floors. One solution would be to increase the grammage of the overlay paper. however Then occur the unwanted loss of brilliance. In addition, an overlay paper alone is not sufficient for certain uses.

For this reason, minerals were incorporated into the resin solutions used for impregnation, which produced improved wear resistance in the overlay paper. These were then applied to the surface of the papers using doctor blades or slot dies. The minerals, which are mainly corundum (alumina), were also applied to the impregnated papers by means of scatterers or sprayers.

This was particularly easy to realize because of the fact that the papers used were sheet goods. This runs as a continuous web through the impregnation and can then be acted upon at a suitable location with the corundum. For a non-web application, this technology is not suitable for a variety of reasons. Firstly, the paper web must be passed through the commissioned work, which would require a repetitive Einfädelungsprozess in discontinuous operation. On the other hand, the resin solution would run between the individual sheets of paper through the commissioned work and would have to be collected and returned to the process.

When applying the corundum melamine resin, it has been found that sedimentation problems occur due to the density differences between the melamine resin and the corundum. This leads to deposits in neck tanks, pumps, pipelines and the roller application units. For this reason, on the one hand, the entire area often has to be freed from deposits by cleaning and, on the other hand, to achieve a certain level of wear, it is necessary to work with a higher amount of corundum. In addition, the mentioned sedimentation leads to inhomogeneities in the commissioned works, which also has to be compensated by a higher dosage. Another serious disadvantage of this technology is that the corundum-containing resin formulations cause considerable wear on all parts of the system that come into contact with the resin formulation. The higher dosage in combination with the sedimentation problems in turn leads to a lower transparency at higher wear classes. This is especially noticeable in dark decors.

Another problem that corundum-containing formulations cause in the further process step of the compression is the sheet metal wear, which is the higher the more corundum in g per square meter are applied and the worse this corundum is covered by corundum-free resin layers. For this reason alone, a required value in the behavior against abrasion should be achieved with as little as possible corundum. Of course, higher corundum consumption also means higher costs and unnecessary consumption of resources.

Another problem is that during plant downtime a rapid aging of the resin approaches with corundum occurs. These must then be disposed of. This leads to increased disposal costs and increased material consumption.

Another problem is that effective quality control on the production line is not possible. The resin recipe indicates only an approximate value of the amount of corundum that should be present on the surface. The reduced orders due to sedimentation, viscosity fluctuations and inhomogeneities are difficult to estimate. For this reason, such a process must be accompanied by the most frequent determination of the behavior against abrasion determination. It takes several hours for higher levels of wear for a determination, which is of course counterproductive for effective process control. Also, the costs of the exam are not negligible. The statements made so far are valid not only for the order on paper webs but also for the order on (printed) board materials.

There are thus various disadvantages: poor distribution of the corundum in the resin solution, high wear on system components (pumps, rollers, etc.), increased consumption of corundum, poor process control, poor transparency and higher costs.

WO 2011/076305 A1 discloses a method and a production line for producing a wood-based panel having a top-side decorative layer and three top and bottom resin layers, the first top-layer resin containing abrasion-resistant particles and the third resin layer containing glass spheres. CA 2 283 835 A1 discloses a method of spreading abrasion-resistant particles onto a wet resin layer. The present invention is therefore based on the technical task, in addition to the safe achievement of high abrasion values, in particular the abrasion classes AC4 to AC6 with simultaneously low pressure plate wear. This should be achieved especially for a process in which printed plates in a variety of formats should be processed. If possible, a process simplification and at least a cost neutrality should be achieved. The disadvantages already discussed should, if possible, no longer occur through a new process. It should also enable effective quality control that provides timely information about the current process.

The stated object is achieved by a method having the features of claim 1 and a production line having the features of claim 12.

The present method thus makes it possible to provide wood-based panels provided with a decorative layer in various formats with high wear resistance in a cost-effective manner. According to the present method, a first resin layer, in particular in the form of a first thermosetting resin layer, such as a melamine-formaldehyde resin layer, is applied to the decorative layer (pretreated or not pretreated) of the wood-based panel. There is initially no drying or drying of the first resin layer, but rather the abrasion-resistant particles are sprinkled evenly onto the wet or still liquid first resin layer on top of the wood-based panel using a suitable scattering device. Because the first Resin layer is still liquid at the time of scattering, the abrasion-resistant particles can sink into the resin layer. Only after the abrasion-resistant particles have been sprinkled onto the first resin layer is a drying step carried out, for example, using a circulating-air dryer, whereby the attrition-resistant particles in the at least one first resin layer are immobilized.

As explained in more detail below, other scatterable materials (such as glass beads, cellulose fibers, wood fibers, etc.) can be sprinkled with the spreader or spreader used in the present process. By scattering the entire abrasion-resistant material (such as corundum) in one layer, instead of the multiple application using the applicator rollers, the layer of abrasion-resistant material can be significantly better sealed off with subsequent resin layers against the press plate. This reduces sheet metal wear. This is also achieved by the lower application rate needed to achieve a certain abrasion resistance.

With the present method, it is possible to reduce the consumption of abrasion-resistant material, to reduce equipment wear, e.g. Wear of the press plate in the press or the resin feed lines is reduced, the application of abrasion-resistant material to the wood-based panel is more uniform, the transparency is improved. Overall, the process costs are reduced due to reduced material and maintenance costs. In addition, the quantity determination of the applied abrasion-resistant material and thus also the quality control is simplified, as explained in more detail below.

The amount of the first resin layer applied to the upper side of the wood-based panel may be between 50-100 g / m ² , preferably 60-80 g / m ² , particularly preferably 70 g / m ² .

The amount of the first resin layer applied to the underside of the wood-based panel may be between 50-100 g / m ² , preferably 60-80 g / m ² , particularly preferably 60 g / m ² . Preferably, the first lower resin layer (eg brownish) is colored to simulate a counter-pull.

The solid content of the resin used for the first resin layer is 50-70% by weight, preferably 50-60% by weight, more preferably 55% by weight for both the top and the bottom.

The first resin layer is preferably applied parallel or simultaneously to the top and bottom of the wood-based panel in at least one double application device (roller application unit).

The applied on the bottom resin layers act in return. By applying the resin layers on the top and bottom of the wood-based panels in approximately the same amounts ensures that the resulting by the applied layers during compression tensile forces on the wood-based panel cancel each other. The counter-coating applied to the underside corresponds in layer construction and the respective layer thickness approximately to the layer sequence applied on the upper side with the difference of the abrasion-resistant particles and glass spheres, as explained in detail below.

The abrasion-resistant particles used to increase the wear resistance preferably comprise corundum (aluminum oxides), boron carbides, silicon dioxides, silicon carbides, the use of corundum being particularly preferred.

In one embodiment, the amount of scattered abrasion-resistant particles is 10 to 50 g / m ² , preferably 10 to 30 g / m ² , particularly preferably 15 to 25 g / m ² . Thus, for example, 14 g / m ² or 23 g / m ² of abrasion-resistant particles can be scattered.

The determination of the applied amount of abrasion resistant material on the wood panel can be made in a simple and accurate manner. This can be done by simply placing one or more shallow trays beneath the spreader or spreader. Subsequently, the spreader is run for a certain defined period of time, the amount of abrasion resistant material collected in the trays is balanced and the balanced amount of abrasion resistant material is divided by the plant feed. This can z. B. the deviation between left - center - be determined right, the stray inaccuracy of the scattering device should be at +/- 1 g / m ² in width.

The amount of the second resin layer applied to the upper side of the wood-based panel may be between 10-50 g / m ² , preferably 20-30 g / m ² , particularly preferably 25 g / m ² .

The amount of the second resin layer applied to the underside of the wood-based panel may be between 30-80 g / m ² , preferably 40-60 g / m ² , particularly preferably 50 g / m ² .

The solid content of the resin used for the second resin layer is 50-70% by weight, preferably 50-60% by weight, more preferably 55% by weight for both the top and the bottom. In accordance with the invention, at least a third resin layer is applied to the top and bottom of the wood-based panel, i. applied to the respective second (dried) resin layer.

The amount of the third resin layer applied to the upper side of the wood-based panel may be between 10-40 g / m ² , preferably 15-30 g / m ² , particularly preferably 20 g / m ² , the solids content being between 50-80% by weight, preferably 60-70% by weight, particularly preferably 60-65% by weight, for example at 61.5% by weight. The resin to be applied as the third resin layer on top of the wood-based panel contains glass beads, the glass beads preferably acting as spacers. The glass beads preferably used have a diameter of 50-100 microns, preferably from 60-80 microns. The application amount of the glass beads, when applied together with the third resin layer, is 1-5 g / m ² , preferably 2-4 g / m ² , particularly preferably 3 g / m ² .

In a further, not claimed, variant, the glass beads can be sprinkled onto the applied on the top of the wood-based panel third resin layer. In this case, ie, when the glass beads are scattered, the application amount of the glass beads is 5-10 g / m ² , preferably 6-8 g / m ² , particularly preferably 6 g / m ² .

The amount of the third resin layer applied to the underside of the wood-based panel may be between 20-70 g / m ² , preferably 30-50 g / m ² , particularly preferably 40 g / m ² at a solids content of 50-70% by weight, preferably 50-70% by weight. 60% by weight, particularly preferably 55% by weight. The third resin layer applied in each case on the upper side and lower side of the wood-based panel is dried in at least one drying device. Following the drying process for the third resin layer, according to the invention at least one fourth resin layer is applied to the upper side and the lower side of the wood-based panel, ie to the respective third resin layer. The amount of the fourth resin layer applied to the upper side of the wood-based panel may be between 10-40 g / m ² , preferably 15-30 g / m ² , particularly preferably 20 g / m ² at a solids content of 50-80% by weight, preferably 60-80% by weight. 70% by weight, particularly preferably 60-65% by weight, for example 61.6% by weight. According to the invention, the resin to be applied as the fourth resin layer on top of the wood-based panel contains glass beads and / or fibers, in particular wood fibers or cellulose fibers. In the case of adding glass beads to the resin to be applied, the application amount of glass beads is 1-5 g / m ² , preferably 2-4 g / m ² , particularly preferably 3 g / m ² . The application amount of the fibers, such as cellulose fibers, when applied together with the fourth resin layer, is between 0.1-0.5 g / m ² , preferably 0.2-0.4 g / m ² , particularly preferably 0 , 25 gsm. The addition of glass beads and / or fibers such as cellulose fibers to the uppermost fourth layer contributes to the wear resistance of the wood-based panel.

The amount of the fourth resin layer applied to the underside of the wood-based panel may be between 10-60 g / m ² , preferably 20-50 g / m ² , particularly preferably 30 g / m ² at a solids content of 50-70% by weight, preferably 50-70% by weight. 60% by weight, particularly preferably 55% by weight.

It should also be noted that it is possible to add further additives, such as hardeners, wetting agents, defoamers and / or release agents, to all resin layers.

The fourth resin layer, which is applied on the upper side and lower side of the wood-based panel, is finally dried in at least one further drying device. The drying of the respective resin layers is preferably carried out to a residual moisture of 6-9% by weight, for example in a circulating air dryer.

In the pressing step following the last drying step, the layer structure is compressed under pressure and temperature in a short-cycle press at temperatures between 150 and 250 ° C., preferably between 180 and 230 ° C., particularly preferably at 200 ° C. and a pressure between 100 and 1000 N / cm ² , preferably 300 and 700 N / cm ² , particularly preferably between 400 and 600 N / cm ² .

In a variant of the present method is as a wood-based panel or as a support plate medium density fiber (MDF), high density fiber (HDF), coarse chip (OSB) or plywood, a cement fiber board and / or gypsum fiber board, a wood-plastic plate, in particular a Wood Plastic Composite (WPC) plate used.

The above-mentioned decorative layer can be applied by direct printing. In the case of direct printing, the application of a water-based, pigmented ink by gravure or digital printing, wherein the water-based pigmented ink is applied in more than one layer, e.g. in the form of two to ten layers, preferably three to eight layers.

In the case of direct printing, the application of the at least one decorative layer takes place as mentioned by means of an analogue gravure printing and / or a digital printing process. The gravure printing process is a printing technique in which the elements to be imaged are present as depressions of a printing form, which is inked before printing. The ink is located primarily in the recesses and is due to the pressure of the printing plate and adhesive forces on the object to be printed, such as. a wood fiber support plate, transferred. On the other hand, in digital printing, the print image is transferred directly from a computer to a printing press, such as a press. transmit a laser printer or inkjet printer. This eliminates the use of a static printing form. Both methods allow the use of aqueous inks and inks or UV-based colorants. It is also conceivable to combine the mentioned printing techniques from gravure and digital printing. A suitable combination of the printing techniques can be done either directly on the support plate or the layer to be printed or even before printing by adjusting the electronic records used.

It is also possible that at least one primer layer is arranged between the wood-based material board or carrier plate and the at least one decorative layer.

The primer layer preferably used here comprises a composition of casein as binder and inorganic pigments, in particular inorganic color pigments. As color pigments, white pigments such as titanium dioxide can be used in the primer layer, or else further color pigments, such as calcium carbonate, barium sulfate or barium carbonate. The primer may contain water as a solvent in addition to the color pigments and casein. It is likewise preferred if the applied pigmented basecoat comprises at least one, preferably at least two, more preferably at least four, successively applied layers or jobs, the application quantity between the layers or applications being the same or different.

The present method thus makes it possible to produce an abrasion-resistant wood-based panel with at least one decorative layer on the upper side, at least one first resin layer on the upper side and underside, at least one layer of abrasion-resistant particles on and / or in the first resin layer on the upper side, and at least one second Resin layer on the top and bottom of the wood-based panel. According to the invention, at least a third and fourth resin layer are provided on the upper side and lower side of the wood-based panel, glass balls or glass beads and / or fibers, in particular cellulose fibers, being contained in the third and fourth resin layer provided on the upper side of the wood-based panel. In a preferred embodiment, the present method makes it possible to produce an abrasion-resistant wood-based panel with the following layer structure (seen from the bottom upwards):
Backing of four resin layers - backing plate - primer layer - print decor layer - first resin layer - layer of abrasion-resistant particles - second resin layer - third resin layer with glass beads - fourth resin layer with glass beads and / or cellulose fibers.

• mindestens eine erste Auftragsvorrichtung zum Auftragen einer ersten Harzschicht auf die Oberseite und Unterseite der Trägerplatte,
• mindestens eine in Verarbeitungsrichtung hinter der ersten Auftragsvorrichtung angeordnete Vorrichtung zum Aufstreuen einer vorbestimmten Menge an abriebfesten Partikeln;
• mindestens eine in Verarbeitungsrichtung hinter der ersten Auftragsvorrichtung und Streuvorrichtung angeordnete erste Trocknungsvorrichtung zum Trocknen der ersten oberen und unteren Harzschicht;
• mindestens eine in Verarbeitungsrichtung hinter der ersten Trocknungsvorrichtung angeordnete zweite Auftragsvorrichtung zum Auftragen einer zweiten Harzschicht auf die Oberseite und Unterseite der Trägerplatte,
• mindestens eine in Verarbeitungsrichtung hinter der zweiten Auftragsvorrichtung angeordnete zweite Trocknungsvorrichtung zum Trocknen der zweiten oberen und unteren Harzschicht;
• mindestens eine in Verarbeitungsrichtung hinter der zweiten Trocknungsvorrichtung angeordnete dritte Auftragsvorrichtung zum Auftragen einer dritten Harzschicht auf die Oberseite, die Glaskugeln enthält, und Unterseite der Trägerplatte (ohne Glaskugeln),
• mindestens eine in Verarbeitungsrichtung hinter der dritten Auftragsvorrichtung angeordnete dritte Trocknungsvorrichtung zum Trocknen der dritten oberen und unteren Harzschicht;
• mindestens eine in Verarbeitungsrichtung hinter der dritten Trocknungsvorrichtung angeordnete vierte Auftragsvorrichtung zum Auftragen einer vierten Harzschicht, die Glaskugeln und/oder Fasern enthält, auf die Oberseite und Unterseite der Trägerplatte (ohne Glaskugeln oder Fasern);
• mindestens eine in Verarbeitungsrichtung hinter der vierten Auftragsvorrichtung angeordnete vierten Trocknungsvorrichtung zum Trocknen der vierten oberen und unteren Harzschicht; und
• mindestens eine in Verarbeitungsrichtung hinter der vierten Trocknungsvorrichtung angeordnete Kurztaktpresse.

The production line for carrying out the present method comprises the following elements:

• at least one first application device for applying a first resin layer to the top side and underside of the carrier plate,
• at least one downstream of the first applicator device arranged in the processing direction for spreading a predetermined amount of abrasion-resistant particles;
• at least one first drying device arranged behind the first application device and scattering device in the processing direction for drying the first upper and lower resin layer;
• at least one downstream in the processing direction behind the first drying device arranged second application device for applying a second resin layer on the top and bottom of the support plate,
• at least one second drying device arranged after the second application device in the processing direction for drying the second upper and lower resin layer;
• at least one third application device arranged behind the second drying device in the processing direction for applying a third resin layer to the upper side, which contains glass spheres, and underside of the carrier plate (without glass spheres),
• at least one third drying device arranged behind the third application device in the processing direction for drying the third upper and lower resin layer;
• at least one downstream in the processing direction downstream of the third drying device arranged fourth applicator for applying a fourth resin layer containing glass beads and / or fibers, on the top and bottom of the support plate (without glass beads or fibers);
• at least one fourth drying device arranged after the fourth application device in the processing direction for drying the fourth upper and lower resin layers; and
• at least one short-cycle press arranged in the processing direction behind the fourth drying device.

The spreader or scattering device is therefore installed in a production line in which aqueous resins can be applied to primed and printed plates via several roller applicators. At the beginning of the process, a resin coating is applied to individual plates, into which the abrasion-resistant material such as corundum is then sprinkled with the spreader.

The spreader provided in the present production line is suitable for spreading powder, granules, fibers and comprises an oscillating brush system. The spreader consists essentially of a storage hopper, a rotating, structured roller and a scraper. In this case, the order quantity of abrasion-resistant material is determined by the rotational speed of the roller.

In one embodiment of the present production line it is additionally provided that the at least one scattering device is surrounded by at least one cabin provided with at least one means for removing dusts occurring in the cabin. The means for removing the dust may be in the form of a suction device or as a device for blowing in air. The injection of air can be achieved through nozzles installed at the plate inlet and outlet, which inject air into the cabin. In addition, these can prevent air movements from creating an inhomogeneous curtain of abrasion-resistant material.

The removal of the dust from abrasion-resistant material from the environment of the spreader is advantageous because in addition to the apparent health burden for working on the production line workers of particulate matter from abrasion-resistant particles deposits on other parts of the production line and leads to increased wear of the same. The arrangement of the scattering device in a cabin therefore not only serves to reduce the health dust load of the environment of the production line but also prevents premature wear.

The scattering device is preferably controlled by a light barrier, the light barrier being arranged in the processing direction in front of the roller (scattering roller) provided below the scattering device. The control of the spreader by a Photoelectric sensor makes sense that between the individual wood-based panels more or less large gaps are. This starts the scattering process as soon as a plate is in front of the scattering roller.

In one embodiment of the present scattering device, at least one funnel for collecting excess abrasion-resistant particles (ie not scattered on the at least one wood-based panel, but rather before the retraction of the wood-based panel by means of the transport device under the scattering roller before derselbigen falling-off abrasion-resistant particles) is provided in front of the scattering roller ,

In a further variant, the hopper is coupled to at least one conveyor and a screening device, wherein the collected in the hopper excess abrasion resistant material is transported via the conveyor to the screening device. The screen meshes of the screening device correspond to the largest grain used of the abrasion resistant particulate material (i.e., about 80-100 μm). In the sifter, debris and clumped material (such as clumped resin or clumped abrasion resistant material) is separated from the collected abrasion resistant material, and the sieved abrasion resistant material can be recycled to the spreader.

Figur 1

eine schematische Darstellung einer Produktionslinie einer Holzwerkstoffplatte unter Verwendung des erfindungsgemäßen Verfahrens.

The invention will be explained in more detail with reference to the figures of the drawings of an embodiment. Show it:

FIG. 1

a schematic representation of a production line of a wood-based panel using the method according to the invention.

The in the FIG. 1 schematically illustrated production line comprises four double application units 1, 2, 3, 4 for simultaneous application of the respective resin layer on the top and bottom of the individual printed material plates eg of printed HDF plates and four arranged in the processing direction behind the double application units convection dryer 1a, 2a, 3a , 4a.

After the first application roller 1, a first scattering device 10 is also provided for uniformly spreading the abrasion-resistant material, such as corundum, onto the first resin layer on top of the HDF plate. The drying of the first resin layer then takes place in the first convection dryer 1a.

This is followed by a second double applicator 2 for applying a second resin layer and a second convection dryer 2a for drying the second resin layer.

The third double applicator 3 for applying the third resin layer may be followed by a further diffuser 20 for applying glass beads to the third resin layer, followed by a third convection dryer 3a for drying the third resin layer. The diffuser 20 for the glass beads is optional. The glass beads are applied according to the invention together with the third resin layer. After applying the fourth resin layer, which in the case of the fourth resin layer on the upper side, e.g. Cellulose fibers may contain, in a fourth Doppelauftragswerk 4 and drying in a fourth convection dryer 4a, the layer structure is pressed in a short-cycle press 5. The pressed plates are cooled and stored.

Embodiment 1

A stack of printed HDF (dark wood decor) is separated in front of the production line and transported through the line at a speed of 28 m / min.

In a first roller application unit, about 70 g of melamine resin fl. (Solids content: 55% by weight) containing the usual auxiliaries (hardener, wetting agent, etc.) are applied to the plate surface. On the underside of the plate, a melamine resin is also applied with the first roller application unit (application rate: 60 g resin fl. / M ² , solids content: about 55% by weight).

Thereafter, 14 g of corundum / m ² (F 200) are sprinkled onto the surface with a spreader. By a distance of about 5 m to the dryer, the corundum is allowed to sink into the melamine resin. Then the plate passes through a circulating air dryer. Thereafter, a melamine resin layer (solid content: 55% by weight) is applied in an amount of 25 g / m ² . These also contain the usual auxiliaries. On the underside of the plate, a melamine resin is also applied with a roller application unit (application rate: 50 g of resin fl./m ² , solids content: about 55% by weight). Again, the plate is dried in a circulating air dryer.

Thereafter, a melamine resin is applied to the plate surface, which additionally contains glass beads. These have a diameter of 60 - 80 microns. The application rate of the resin is about 20 g melamine resin fl./m ² (solids content: 61.5% by weight). In addition to the hardener and the wetting agent, the formulation also contains a release agent. The order quantity of glass beads is about 3 g / m ² . On the underside of the plate, a melamine resin is also applied with a roller application unit (application rate: 40 g resin fl. / M ² , solids content: about 55% by weight). The plate is again dried in a circulating air dryer and then coated again with a melamine resin containing glass beads. Another component is cellulose (Vivapur 302). Again about 20 g of melamine resin fl./m ² (solids content: 61.6% by weight) are applied. Again, about 3 g of glass beads and 0.25 g of cellulose / m ^{2 are} applied. In addition to the hardener and the wetting agent, the formulas also contain a release agent. On the underside of the plate, a melamine resin is also applied with a roller application unit (application rate: 30 g of resin fl. / M ² , solids content: about 55% by weight). The resin is again dried in a circulating air dryer and then the plate is pressed in a short-cycle press at 200 ° C and a pressure of 400 N / cm ² . The pressing time was 10 seconds. The structural element used was a press plate with a wood structure.

For comparison, a plate was pressed in which the corundum was applied via a roller application. The application rates of resin were at the same level as the plate which had been sprinkled with corundum. The commissioned works 1 to 2 contained corundum-containing formulations. In recent projects, the resins contained glass beads or glass beads and cellulose. By a gravimetric determination the order quantity was determined with approx. 20 g of corundum / m ² . From both samples the behavior against abrasion according to DIN EN 15468 was determined. The transparency of the surface was assessed visually. The following values resulted: Sample exam Corundum scattered Corundum roller application Behavior against abrasion stress (DIN EN 15468) (double determination) 4200/4400 Um. 4000/4100 Um. transparency Good transparency Slight transparency disturbances in Holzpore

Comparative Example 1

A stack of printed HDF (dark wood decor) is separated in front of the production line and transported through the line at a speed of 28 m / min.

In a first roller application unit, about 70 g of melamine resin fl. (Solids content: 55% by weight) containing the usual auxiliaries (hardener, wetting agent, etc.) are applied to the plate surface. On the underside of the plate, a melamine resin is also applied with a roller application unit (application rate: 60 g resin fl. / M ² , solids content: about 55% by weight).

23 g of corundum / m ² (F 200) are sprinkled onto the surface with a spreading apparatus. By a distance of about 5 m to the dryer, the corundum is allowed to sink into the melamine resin. Then the plate passes through a circulating air dryer.

Thereafter, a second melamine resin layer (solid content: 55% by weight) is applied in an amount of 25 g / m ² . These also contain the usual auxiliaries. On the underside of the plate, a second melamine resin is also applied with a roller application unit (application rate: 50 g resin fl. / M ² , solids content: about 55% by weight). Again, the plate is dried in a circulating air dryer.

Following the drying process, a third melamine resin is applied again with a roll aggregate. The application rate of the resin is about 20 g melamine resin fl./m ² (solids content: 61.5% by weight). In addition to the hardener and the wetting agent, the formulation also contains a release agent. A third melamine resin is also applied to the underside of the plate with a roller application unit (application rate: 40 g of resin fl. / M ² , solids content: about 55% by weight). Thereafter, about 6 g of glass balls / m ^{2 are} sprinkled with a scattering unit. These had a diameter of 60-80 microns. The plate is again dried in a circulating air dryer and then coated again with a fourth melamine resin containing cellulose (Vivapur 302). In turn, about 20 g of melamine resin fl./m ² (solids content: 56.0% by weight) are applied. In this case, 0.25 g cellulose / m ^{2 are} applied. A fourth melamine resin is also applied to the underside of the plate with a roller application unit (application rate: 30 g of resin fl./m ² , solids content: about 55% by weight). In addition to the hardener and the wetting agent, the formulas also contain a release agent contain. The resin is again dried in a circulating air dryer and then the plate is pressed in a short-cycle press at 200 ° C and a pressure of 400 N / cm ² . The pressing time was 10 seconds. The structural element used was a press plate with a wood structure.

For comparison, a plate was pressed in which the corundum was applied via a roller application. The application rates of resin in this plate were higher than that at which the corundum was scattered about 20 g / m ² (solid). In the first three commissioned works, corundum-containing formulations were used. In the last commissioned work contained the melamine resin glass beads and cellulose. The application rates of the two components were comparable to those of the scattered plate. By a gravimetric determination the order quantity was determined with approx. 30 g of corundum / m ² . From both samples the behavior against abrasion according to DIN EN 15468 was determined. The transparency of the surface was assessed visually. The following values resulted: Sample exam Corundum scattered Corundum roller application Behavior against abrasion stress (DIN EN 15468) (double determination) 6300/6500 Um. 6200/5950 Um. transparency Good transparency greater transparency disturbances in Holzpore and in the entire surface

Comparative Example 2:

In a large-scale test 10,000 printed HDFs (size: 5600 x 2070 mm, dark wood decor) were separated in front of the production line and transported through the line at a speed of 28 m / min.

In a first roller application unit, about 70 g of melamine resin fl. (Solids content: 55% by weight) containing the usual auxiliaries (hardener, wetting agent, etc.) on the plate surface applied. A melamine resin is applied to the underside of the plate also with a roller application unit applied (application amount:. 60 g resin fl / m ^2, solid content: about 55% by weight).

23 g of corundum / m ² (F 200) are sprinkled onto the surface with a spreading apparatus. By a distance of about 5 m to the dryer, the corundum is allowed to sink into the melamine resin. Then the plate passes through a circulating air dryer.

Thereafter, a second melamine resin layer (solid content: 55% by weight) is applied in an amount of 25 g / m ² . These also contain the usual auxiliaries. On the underside of the plate, a second melamine resin is also applied with a roller application unit (application rate: 50 g resin fl. / M ² , solids content: about 55% by weight). Again, the plate is dried in a circulating air dryer.

Following the drying process, melamine resin is applied again with a roll aggregate. The application rate of the resin is about 20 g melamine resin fl./m ² (solids content: 61.5% by weight). In addition to the hardener and the wetting agent, the formulation also contains a release agent. On the underside of the plate, a melamine resin is also applied with a roller application unit (application rate: 40 g resin fl. / M ² , solids content: about 55% by weight). Thereafter, about 6 g of glass balls / m ^{2 are} sprinkled with a scattering unit. These had a diameter of 60-80 microns. The plate is again dried in a circulating air dryer and then again coated with a melamine resin containing cellulose (Vivapur 302). In turn, about 20 g of melamine resin fl./m ² (solids content: 56.0% by weight) are applied. In this case, 0.25 g cellulose / m ^{2 are} applied. On the underside of the plate, a melamine resin is also applied with a roller application unit (application rate: 30 g of resin fl. / M ² , solids content: about 55% by weight). In addition to the hardener and the wetting agent, the formulas also contain a release agent. The resin is again dried in a circulating air dryer and then the plate is pressed in a short-cycle press at 200 ° C and a pressure of 400 N / cm ² . The pressing time was 10 seconds. The structural element used was a press plate with a wood structure.

For comparison, 10,000 plates were pressed, in which the corundum was applied via a roller application. The application rates of resin in this plate were higher than that at which the corundum was scattered about 20 g / m ² (solid). In the first three commissioned works, corundum-containing formulations were used. In the last commissioned work contained the melamine resin glass beads and cellulose. The order quantities of both components were comparable to those of the scattered plate. By a gravimetric determination the order quantity was determined with approx. 30 g of corundum / m ² . From both samples the behavior against abrasion according to DIN EN 15468 was determined. The transparency of the surface was assessed visually. The following values resulted: Sample exam Corundum scattered (after 10,000 compressions) Corundum roller application (after 10000 pressings) Gloss level change *) Measured (initial value: 15 highlights) -1 highlight -4 highlights Gloss level change visual assessment No abnormalities Significant visible wear on the pressboard corners *) The gloss level measurement was carried out with a gloss level measuring device from the company Dr. Ing. Long at a measuring angle of 60 °, DIN EN 13 722: 2004-10

Claims (14)

1. Method for producing an abrasion-resistant wood material board which has at least one decorative layer, in particular as a printed decoration, on the upper side, comprising the steps:

   - applying at least one first resin layer to the at least one decorative layer on the upper side and to the underside of the wood material board;

   - uniformly scattering abrasion-resistant particles onto the first resin layer on the upper side of the wood material board;

   - drying the first resin layer provided with the abrasion-resistant particles on the upper side, and the first resin layer on the underside of the wood material board in at least one drying device;

   - applying at least one second resin layer to the dried first resin layer provided with the abrasion-resistant particles on the upper side, and the dried first resin layer on the underside of the wood material board;

   - drying the second resin layer on the upper side and the underside of the wood material board respectively in at least one drying device;

   - applying at least one third resin layer to the upper side and the underside of the wood material board respectively, wherein the resin to be applied as third resin layer to the upper side of the wood material board contains glass spheres;

   - drying the third resin layer applied to the upper side and underside of the wood material board respectively in at least one drying device;

   - applying at least one fourth resin layer to the upper side and the underside of the wood material board respectively; wherein the resin to be applied as fourth resin layer to the upper side of the wood material board contains glass spheres and/or fibres;

   - drying the fourth resin layer applied to the upper side and the underside of the wood material board respectively in at least one drying device; and

   - pressing the layer structure.
2. Method according to Claim 1, characterized in that the quantity of the first resin layer applied to the upper side of the wood material board is between 50-100 g/m², preferably 60-80 g/m², in particular preferably 70 g/m².
3. Method according to Claim 1 or 2, characterized in that the abrasion-resistant particles comprise particles made of corundum, boron carbide, silicon dioxide, silicon carbide.
4. Method according to one of the preceding claims, characterized in that the quantity of abrasion-resistant particles scattered on is 10 to 50 g/m², preferably 10 to 30 g/m², in particular preferably 15 to 25 g/m².
5. Method according to one of the preceding claims, characterized in that the quantity of the second resin layer applied to the upper side of the wood material board is between 10-50 g/m², preferably 20-30 g/m², in particular preferably 25 g/m².
6. Method according to one of the preceding claims, characterized in that the quantity of the third resin layer applied to the upper side of the wood material board is between 10-40 g/m², preferably 15-30 g/m², in particular preferably 20 g/m², wherein the solids content lies between 50-80% by weight, preferably 60-70% by weight, in particular preferably 60-65% by weight.
7. Method according to one of the preceding claims, characterized in that the application quantity of the glass spheres, if these are applied together with third resin layer, is 1-5 g/m², preferably 2-4 g/m², in particular preferably 3 g/m².
8. Method according to one of the preceding claims, characterized in that the resin to be applied as fourth resin layer to the upper side of the wood material board contains wood fibres or cellulose fibres.
9. Method according to one of the preceding claims, characterized in that the quantity of the fourth resin layer applied to the upper side of the wood material board is between 10-40 g/m², preferably 15-30 g/m², in particular preferably 20 g/m², with a solids content of 50-80% by weight, preferably 60-70% by weight, in particular preferably 60-65% by weight.
10. Method according to one of the preceding claims, characterized in that the glass spheres in the fourth resin layer are applied in a quantity of 1-5 g/m², preferably 2-4 g/m², in particular preferably 3 g/m².
11. Method according to one of the preceding claims, characterized in that the fibres in the fourth resin layer are applied in a quantity between 0.1-0.5 g/m², preferably 0.2-0.4 g/m², in particular preferably 0.25 g/m².
12. Production line for carrying out a method according to one of the preceding claims, comprising

    - at least one first application device for applying a first resin layer to the upper side and underside of the core board,

    - at least one device, arranged downstream as a first application device in the processing direction, for scattering a predetermined quantity of abrasion-resistant particles;

    - at least one first drying device, arranged downstream of the first application device and scattering device in the processing direction, for drying the first upper and lower resin layer;

    - at least one second application device, arranged downstream of the first drying device in the processing direction, for applying a second resin layer to the upper side and underside of the core board,

    - at least one second drying device, arranged downstream of the second application device in the processing direction, for drying the second upper and lower resin layer;

    - at least one third application device, arranged downstream of the second drying device in the processing direction, for applying a third resin layer to the upper side and underside of the core board, wherein the resin to be applied as third resin layer to the upper side of the wood material board contains glass spheres;

    - at least one third drying device, arranged downstream of the third application device in the processing direction, for drying the third upper and lower resin layer;

    - at least one fourth application device, arranged downstream of the third drying device in the processing direction, for applying a fourth resin layer to the upper side and underside of the core board, wherein the resin to be applied as fourth resin layer to the upper side of the wood material board contains glass spheres and/or fibres;

    - at least one fourth drying device, arranged downstream of the fourth application device in the processing direction, for drying the fourth upper and lower resin layer; and

    - at least one short-cycle press arranged downstream of the fourth drying device in the processing direction.
13. Production line according to Claim 12, characterized in that the at least one scattering device is arranged in at least one booth, which is provided with at least one means for removing dust occurring in the booth.
14. Wood material board that can be produced by a method according to one of Claims 1 to 11, comprising at least one decorative layer on the upper side, at least one first resin layer, applied in a quantity between 60 and 100 g/m², on the upper side and underside, at least one layer of abrasion-resistant particles in the first resin layer on the upper side, at least one second resin layer on the upper side and underside of the wood material board, at least one third resin layer on the upper side and underside, wherein glass spheres are contained in the third resin layer on the upper side, and at least one fourth resin layer on the upper side and underside, wherein glass spheres and/or fibres are contained in the fourth resin layer on the upper side.

Images