EP3458281B1 - Production line for producing an abrasion-resistant wood material panel - Google Patents

Description

The present invention relates to a production line for carrying out a method for producing an abrasion-resistant wood-based panel according to claim 1.

Description

A large number of products or product surfaces that are exposed to wear due to mechanical stress must be protected from premature damage or destruction due to wear by applying wear-resistant layers. These products can be, for example: B. furniture, interior panels, floors, etc. Depending on the frequency and intensity of use, different protective measures must be applied so that the user can be guaranteed the longest possible service life.

A large number of the products mentioned above have decorative surfaces that quickly become unsightly when worn due to intensive use and/or can no longer be cleaned. These decorative surfaces often consist of papers impregnated with thermoset resins, which are pressed onto the wooden material supports used in so-called short-cycle presses. Melamine-formaldehyde resin is often used as a thermosetting resin.

So-called overlay papers, which are thin papers containing α-cellulose, have long been used to protect decorative surfaces. After being impregnated with melamine-formaldehyde resins and pressed onto the decorative papers, these have a high level of transparency, so that the brilliance of the decor is not or only slightly affected.

However, the improvement in wear resistance through these overlay papers is not sufficient in all cases. The overlay solutions were sufficient for a kitchen worktop or a counter, but they are not sufficient for more heavily used surfaces or even floors. A solution here would be to increase the grammage of the overlay paper. However, the unwanted loss of brilliance then occurs. In addition, for certain uses, overlay paper alone is not sufficient.

Therefore, minerals were introduced into the resin solutions used for impregnation, which created improved wear resistance in the overlay paper. These were then applied to the surface of the papers using squeegees or slot nozzles. The minerals, which are primarily corundum (aluminum oxide), were also applied to the impregnated papers using scattering or spraying devices.

This was particularly easy to achieve from a technical point of view because the paper used was web material. This runs as an endless path through the impregnation channel and can then be applied with the corundum at a suitable point. For a variety of reasons, this technology is not suitable for the use of non-endless webs. On the one hand, the paper web must be guided through the applicator, which would require a constantly repeating threading process in discontinuous operation. On the other hand, the resin solution would run through the applicator between the individual sheets of paper and would have to be collected and returned to the process.

When applying the corundum-containing melamine resin, it has been shown that problems arise due to sedimentation due to the density differences between the melamine resin and the corundum. This leads to deposits in batch tanks, pumps, pipelines and the roller application units. Therefore, on the one hand, the entire area often has to be cleaned of the deposits and, on the other hand, a higher application of corundum must be applied to achieve a certain wear value. In addition, the above-mentioned sedimentation leads to inhomogeneities in the applied works, which must also be compensated for by a higher dosage. Another serious disadvantage of this technology is that the corundum-containing resin formulations cause considerable wear on all system parts that come into contact with the resin formulation. The higher dosage in combination with the sedimentation problems in turn leads to poorer transparency at higher wear classes. This is particularly noticeable in dark decors.

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

Another problem is that the resin mixtures with corundum age quickly when the system is shut down. 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 only gives you 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 determining the behavior against abrasion as frequently as possible. With higher wear classes, it takes several hours to make a determination, which is of course counterproductive for effective process control. The costs of the test should not be neglected either. What has been said so far applies not only to the application to paper webs but also to the application to (printed) board materials.

This results in 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 with a decorative layer on the top and three resin layers on the top and bottom, the first upper resin layer containing abrasion-resistant particles and the third resin layer containing glass balls. CA 2 283 835 A1 discloses a method for sprinkling abrasion-resistant particles onto a wet resin layer.

The present invention is therefore based on the technical task of reliably achieving high abrasion values, in particular abrasion classes AC4 to AC6, while at the same time keeping the press plate wear low. This should be achieved above all for a process in which printed panels are processed in a wide variety of formats should. If possible, process simplification and at least cost neutrality should be achieved. If possible, the disadvantages already discussed should no longer occur through a new process. This should also enable effective quality control that provides timely information about the current process.

The object is achieved according to the invention by a production line with the features defined in claim 1.

• Auftragen von mindestens einer ersten Harzschicht auf die mindestens eine Dekorschicht auf der Oberseite und auf die Unterseite der Holzwerkstoffplatte,
• gleichmäßiges Aufstreuen von abriebfesten Partikeln auf die erste Harzschicht auf der Oberseite der Holzwerkstoffplatte;
• Trocknen der mit den abriebfesten Partikeln versehenen ersten Harzschicht auf der Oberseite und der ersten Harzschicht auf der Unterseite der Holzwerkstoffplatte in mindestens einer Trocknungsvorrichtung;
• Auftragen von mindestens einer zweiten Harzschicht auf die getrocknete mit den abriebfesten Partikeln versehene erste Harzschicht auf der Oberseite und die getrocknete erste Harzschicht auf der Unterseite der Holzwerkstoffplatte;
• Trocknen der jeweils zweiten Harzschicht auf der Oberseite und der Unterseite der Holzwerkstoffplatte in mindestens einer Trocknungsvorrichtung; und
• Verpressen des Schichtaufbaus.

Accordingly, a production line is provided for carrying out a method for producing an abrasion-resistant wood-based panel, with at least one decorative layer, in particular as a printed decoration, being provided on the top side. The present procedure includes the following steps:

• Applying at least a first resin layer to the at least one decorative layer on the top and bottom of the wood-based panel,
• evenly sprinkling abrasion-resistant particles onto the first resin layer on the top of the wood-based panel;
• 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-based panel in at least one drying device;
• Applying at least a 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-based panel;
• Drying the second resin layer on the top and bottom of the wood-based panel in at least one drying device; and
• Pressing the layer structure.

The present method therefore enables the provision of wood-based panels provided with a decorative layer in various formats (ie as piece goods and not in the form of an endless web) with high wear resistance in a discontinuous process 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 spread evenly onto the wet or still liquid first resin layer on the top of the wood-based panel using a suitable scattering device. Since the first resin layer is still liquid at the time of spreading, 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 abrasion-resistant particles are fixed in the at least one first resin layer. The abrasion-resistant particles are therefore located in a first resin layer, which is provided directly on the decorative layer and which is covered by at least one further, preferably several further resin layers. The abrasion-resistant particles are therefore not provided in an outer cover layer (and therefore do not protrude from the resin layer), but rather are provided in a lower resin layer. By covering the abrasion-resistant particles with additional resin layers, wear on the pressed plates can be reduced. It should also be noted that the introduction of the abrasion-resistant particles does not serve to provide non-slip panels, but rather is intended to protect the decorative layer, which is preferably applied by direct printing, from abrasion.

As explained in detail below, the scattering device or scattering apparatus used in the present method can also be used to scatter other scatterable materials (such as glass balls, cellulose fibers, wood fibers, etc.). By spreading the entire abrasion-resistant material (such as corundum) in one layer, instead of applying it multiple times with the help of the applicator rollers, the layer of abrasion-resistant material can be sealed off significantly better against the press sheet with subsequent resin layers. This reduces sheet metal wear. This is also achieved by the lower application quantity required to achieve a certain abrasion resistance.

With the present method, a reduction in the consumption of abrasion-resistant material is possible, the wear and tear on the system, such as wear on the press sheet in the press or the resin supply lines, is reduced, the application of abrasion-resistant material to the wood-based panel is more uniform, and the transparency is improved. Overall, the Process costs reduced due to reduced material and maintenance costs. In addition, the determination of the quantity of the applied abrasion-resistant material and thus also the quality control is simplified, as explained in detail below.

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

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

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

The resin layer(s) applied to the underside act as a counterbalance. Applying the resin layers to the top and bottom of the wood-based panels in approximately the same quantities ensures that the tensile forces on the wood-based panel caused by the applied layers during pressing cancel each other out. The layer structure and the respective layer thickness of the counterweight applied to the underside approximately corresponds to the layer sequence applied to the top with the difference in the abrasion-resistant particles and glass balls, as will be explained in detail below.

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

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

In one embodiment, abrasion-resistant particles with a grain size between 50 and 100 μm, preferably between 70 and 100 μm, are used. In particular, abrasion-resistant particles with a grain size between 45 and 90 µm, preferably 53 to 75 µm, will be scattered in an amount of between 10 to 30 g/m ² , preferably between 15 and 20 g/m 2 . In a particularly preferred embodiment, abrasion-resistant particles with a grain size of between 70 and 90 μm are scattered in an amount of 20 g/m ² .

Abrasion-resistant particles with grain sizes in classes F180 to F220, preferably F200, are used. The grain size of class F180 covers a range of 53 - 90 µm and F220 of 45-75 µm (FEPA standard). In one variant, white corundum with a main grain range of 53-75 µm is used as abrasion-resistant particles. In a particularly preferred embodiment, corundum particles of class F200 are used, where F200 is a mixture between F180 and F220.

Abrasion-resistant particles with a smaller particle size of 40 µm and smaller, on the other hand, are not suitable for scattering because the fine content and thus the dust formation is too high and, on the other hand, such grains are not sufficiently free-flowing. Particularly in a discontinuous scattering process such as in the present case, such fine particles can lead to undesirable turbulence.

The determination of the amount of abrasion-resistant material applied to the wooden panel can be carried out in a simple and precise manner. This can be done by simply placing one or more flat bowls underneath the spreading device or the spreading unit. The spreading device is then left running for a certain defined period of time, the amount of abrasion-resistant material collected in the trays is weighed and the balanced amount of abrasion-resistant material is divided by the system feed. This allows e.g. B. simply determine the deviation between left - center - right, whereby the spreading accuracy of the spreading device should be +/- 1 g/m ² in width.

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

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

In a further embodiment of the present method, at least a third resin layer is applied to the top and bottom of the wood-based panel, i.e. to the respective second (dried) resin layer.

The amount of the third resin layer applied to the top of the wood-based panel can be between 10-40 g/m ² , preferably 15-30 g/m ² , particularly preferably 20 g/m ² , with the solids content being between 50-80% by weight, preferably 60-70% by weight, particularly preferably 60-65% by weight, for example 61.5% by weight.

In a variant, the resin to be applied as a third resin layer to the top of the wood-based panel can contain glass balls, with the glass balls preferably functioning as spacers. The glass balls preferably used have a diameter of 50-100 µm, preferably 60-80 µm. The application amount of the glass beads when they are 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 variant, the glass balls can be sprinkled onto the third resin layer applied to the top of the wood-based panel. In this case, ie when the glass balls are scattered, the application amount of the glass balls 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 can be between 20-70 g/m ² , preferably 30-50 g/m ² , particularly preferably 40 g/m ² with a solids content of 50-70% by weight, preferably 50-50 g/m 2 . 60% by weight, particularly preferably 55% by weight.

It is also advantageous if the third resin layer applied to the top and bottom of the wood-based panel is dried in at least one drying device.

Following the drying process for the third resin layer, it is optionally possible to apply at least a fourth resin layer to the top and bottom of the wood-based panel, i.e. to the respective third resin layer.

The amount of the fourth resin layer applied to the top of the wood-based panel can be between 10-40 g/m ² , preferably 15-30 g/m ² , particularly preferably 20 g/m ² with a solids content of 50-80% by weight, preferably 60%. 70% by weight, particularly preferably 60-65% by weight, for example 61.6% by weight.

In a further variant of the present method, the resin to be applied as the fourth resin layer to the top of the wood-based panel can contain glass beads and/or fibers, in particular wood fibers or cellulose fibers. If glass beads are added to the resin to be applied, the amount of glass beads applied 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 g/m2. The addition of glass beads and/or fibers such as cellulose fibers to the top 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 can be between 10-60 g/m ² , preferably 20-50 g/m ² , particularly preferably 30 g/m ² with a solids content of 50-70% by weight, preferably 50-50 g/m 2 . 60% by weight, particularly preferably 55% by weight.

It should also be noted that additional additives such as hardeners, wetting agents, defoamers and/or release agents can be added to all resin layers.

The fourth resin layer applied to the top and bottom of the wood-based panel is finally dried in at least one further drying device dried. The respective resin layers are preferably dried to a residual moisture content 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 pressed under the influence of 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, a medium-density fiber (MDF), high-density fiber (HDF), coarse chipboard (OSB) or plywood board, a cement fiber board and/or gypsum fiber board, a wood-plastic board, in particular a wood board is used as the wood-based board or as the carrier board Plastic Composite (WPC) panel used.

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

In the case of direct printing, the at least one decorative layer is applied, as mentioned, using an analog gravure printing and/or a digital printing process. The gravure printing process is a printing technique in which the elements to be depicted are present as depressions in a printing form that is inked before printing. The printing ink is primarily located in the depressions and is transferred to the object to be printed, such as a wood fiber board, due to the contact pressure of the printing form and adhesion forces. In contrast, with digital printing, the printed image is transferred directly from a computer to a printing machine, such as a laser printer or inkjet printer. This eliminates the need to use a static printing form. In both processes, the use of water-based paints and inks or UV-based coloring agents is possible. It is also conceivable to combine the printing techniques mentioned from gravure and digital printing. A suitable combination of printing techniques can be done directly on the carrier plate or the layer to be printed or before printing by adapting the electronic data sets used.

It is also possible for at least one primer layer to be arranged between the wood material board or carrier board and the at least one decorative layer.

The primer layer preferably used comprises a composition of casein as a binder and inorganic pigments, in particular inorganic color pigments. White pigments such as titanium dioxide or other color pigments such as calcium carbonate, barium sulfate or barium carbonate can be used as color pigments in the primer layer. In addition to the color pigments and casein, the primer can also contain water as a solvent. It is also preferred if the applied pigmented base layer consists of at least one, preferably at least two, particularly preferably at least four layers or orders applied one after the other, whereby the amount applied between the layers or orders can be the same or different.

The present method thus enables the production of an abrasion-resistant wood-based panel with at least one decorative layer on the top, at least a first resin layer on the top and bottom, at least one layer of abrasion-resistant particles on and / or in the first resin layer on the top, and at least a second Resin layer on the top and bottom of the wood-based panel.

In a further embodiment, at least a third and fourth resin layer are provided on the top and bottom of the wood-based panel, wherein glass balls and / or fibers, in particular cellulose fibers, can be contained in the third and fourth resin layers provided on the top of the wood-based panel.

In a preferred embodiment, the present method enables the production of an abrasion-resistant wood-based panel with the following layer structure (seen from bottom to top):
Counterlayer made of four resin layers - carrier plate - primer layer - print decoration layer - first resin layer - layer of abrasion-resistant particles - second resin layer - third resin layer with glass balls - fourth resin layer with glass balls and / or cellulose fibers.

• mindestens eine erste Auftragsvorrichtung zum Auftragen einer ersten Harzschicht auf die Oberseite und/oder Unterseite der Trägerplatte,
• mindestens eine in Verarbeitungsrichtung hinter der ersten Auftragsvorrichtung angeordnete Vorrichtung zum Aufstreuen einer vorbestimmten Menge an abriebfesten Partikeln; wobei die mindestens eine Streuvorrichtung aus einem Vorratstrichter, einer sich drehenden, strukturierten Streuwalze und einem Abstreifer besteht,
• mindestens eine in Verarbeitungsrichtung hinter der ersten Auftragsvorrichtung und Streuvorrichtung angeordnete erste Trocknungsvorrichtung zum Trocknen der ersten oberen und/oder unteren Harzschicht;
• mindestens eine in Verarbeitungsrichtung hinter der ersten Trocknungsvorrichtung angeordnete zweite Auftragsvorrichtung zum Auftragen einer zweiten Harzschicht auf die Oberseite und/oder Unterseite der Trägerplatte,
• mindestens eine in Verarbeitungsrichtung hinter der zweiten Auftragsvorrichtung angeordnete zweite Trocknungsvorrichtung zum Trocknen der zweiten oberen und/oder unteren Harzschicht; und
• mindestens eine Kurztaktpresse zum Verpressen des Schichtaufbaus.

The production line according to the invention 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 and/or bottom of the carrier plate,
• at least one device arranged behind the first application device in the processing direction for sprinkling a predetermined amount of abrasion-resistant particles; wherein the at least one spreading device consists of a storage hopper, a rotating, structured spreading roller and a scraper,
• at least one first drying device arranged behind the first application device and spreading device in the processing direction for drying the first upper and/or lower resin layer;
• at least one second application device arranged behind the first drying device in the processing direction for applying a second resin layer to the top and/or bottom of the carrier plate,
• at least one second drying device arranged behind the second application device in the processing direction for drying the second upper and/or lower resin layer; and
• at least one short-cycle press for pressing the layer structure.

The production line according to the invention comprises a light barrier and is designed such that the at least one spreading device is controlled by the light barrier, the light barrier being arranged in the processing direction in front of the spreading roller provided in the spreading device.

• mindestens eine in Verarbeitungsrichtung hinter der zweiten Trocknungsvorrichtung angeordnete dritte Auftragsvorrichtung zum Auftragen einer dritten Harzschicht auf die Oberseite, die zum Beispiel Glaskugeln enthalten kann, und/oder 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 zum Beispiel Glaspartikel bzw. Glaskugeln und/oder Fasern enthalten kann, auf die Oberseite und/oder 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.

In a preferred embodiment, the production line for carrying out the present method further comprises

• at least one third application device arranged behind the second drying device in the processing direction for applying a third resin layer to the top, which can contain, for example, glass beads, and/or the bottom of the carrier plate (without glass beads),
• at least one third drying device arranged behind the third application device in the processing direction for drying the third upper and lower resin layers;
• at least one fourth application device arranged behind the third drying device in the processing direction for applying a fourth resin layer, which may contain, for example, glass particles or glass balls and / or fibers, to the top and / or bottom of the carrier plate (without glass balls or fibers);
• at least one fourth drying device arranged behind 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 behind the fourth drying device in the processing direction.

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

The spreading device provided in the present production line is suitable for spreading powder, granules, fibers and includes an oscillating brush system. The spreading device according to the invention essentially consists of a supply hopper, a rotating, structured roller and a scraper. The amount of abrasion-resistant material applied is determined by the speed of rotation of the roller.

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

The removal of the dust made of abrasion-resistant material from the surroundings of the spreading device is advantageous because, in addition to the obvious health hazard for the workers working on the production line, the fine dust made of abrasion-resistant particles also accumulates other parts of the production line and leads to increased wear on the same. The arrangement of the spreading device in a cabin therefore not only serves to reduce the health dust pollution in the area around the production line but also prevents premature wear.

According to the invention, the spreading device is controlled by a light barrier, the light barrier being arranged in the processing direction in front of the roller (spreading roller) provided below the spreading device. Controlling the spreading device using a light barrier makes sense because there are more or less large gaps between the individual wood-based panels. This starts the spreading process as soon as a panel is in front of the spreading roller.

In one embodiment of the present spreading device, at least one funnel is provided in front of the spreading roller for collecting excess abrasion-resistant particles (i.e. not on the at least one wood-based panel, but rather abrasion-resistant particles falling under the spreading roller in front of the same before the wood-based panel is inserted with the aid of the transport device). .

In a further variant, the funnel is coupled to at least one conveyor device and a sieve device, with the excess abrasion-resistant material collected in the funnel being transported to the sieve device via the conveyor device. The sieve meshes of the sieve device correspond to the largest grain of abrasion-resistant particulate material used (i.e. approx. 80-100 µm). In the screening device, dirt particles and clumped material (such as clumped resin or clumped abrasion-resistant material) are separated from the collected abrasion-resistant material and the screened abrasion-resistant material can be returned (recycled) to the spreader.

Figur 1

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

The invention is explained in more detail below with reference to the figures of the drawings using an exemplary embodiment. Show it:

Figure 1

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

The ones in the Figure 1 Production line shown schematically includes four double application units 1, 2, 3, 4 for the simultaneous application of the respective resin layer to the top and bottom of the individual printed material panels, for example printed HDF panels and four convection dryers 1a, 2a, 3a, 4a arranged behind the double application units in the processing direction.

After the first application roller 1, a first spreading device 10 is also provided for evenly spreading the abrasion-resistant material such as corundum onto the first resin layer on the top of the HDF board. The first resin layer is then dried 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 can be followed by a further scattering device 20 for applying glass balls 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 balls is optional. The glass balls can also be applied together with the third layer of resin.

After applying the fourth resin layer, which in the case of the fourth resin layer can contain cellulose fibers on the top, for example, in a fourth double applicator 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.

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, approx. 70 g of melamine resin fl. (solids content: 55% by weight) containing the usual auxiliary materials (hardener, wetting agent, etc.) are applied to the board surface. A melamine resin is also applied to the underside of the board using the first roller application unit (application quantity: 60 g resin fl./m ² , solids content: approx. 55% by weight).

Then 14 g of corundum/m ² (F 200) are sprinkled onto the surface using a spreading apparatus. By leaving a distance of approx. 5 m from the dryer, it becomes corundum allows it to sink into the melamine resin. The plate then goes through a circulating air dryer. A melamine resin layer (solids content: 55% by weight) is then applied in an amount of 25 g/m ² . This also contains the usual auxiliary ingredients. A melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 50 g resin fl./m ² , solids content: approx. 55% by weight). The plate is dried again in a circulating air dryer.

A melamine resin, which also contains glass balls, is then applied to the surface of the plate. These have a diameter of 60 - 80 µm. The application quantity of the resin is approx. 20 g melamine resin fl./m ² (solids content: 61.5% by weight). In addition to the hardener and wetting agent, the recipe also contains a release agent. The application quantity of glass balls is approx. 3 g/m ² . A melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 40 g resin fl./m ² , solids content: approx. 55% by weight). The plate is dried again in a circulating air dryer and then coated again with a melamine resin that contains glass beads. Cellulose (Vivapur 302) is included as a further component. Approximately 20 g of melamine resin fl./m ² (solids content: 61.6% by weight) are again applied. Approximately 3 g of glass beads and 0.25 g of cellulose/m ² are applied again. In addition to the hardener and wetting agent, the recipes also contain a release agent. A melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 30 g resin fl./m ² , solids content: approx. 55% by weight). The resin is again dried in a circulating air dryer and then the panel is pressed in a short-cycle press at 200 ° C and a pressure of 400 N / cm ² . The pressing time was 10 seconds. A pressed sheet metal with a wooden structure was used to provide structure.

For comparison, a plate was pressed in which the corundum was applied using a roller application. The amounts of resin applied were at the same level as for the board that had been sprinkled with corundum. The commissioned works 1 to 2 contained recipes containing corundum. In the most recent commissioned works, the resins contained glass beads or glass beads and cellulose. The application quantity was determined to be approx. 20 g corundum/m ² through a gravimetric determination. The behavior of both samples against abrasion was determined in accordance with DIN EN 15468. The transparency of the surface was assessed visually. This resulted in the following values: 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 wood pores

Example 2:

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, approx. 70 g of melamine resin fl. (solids content: 55% by weight) containing the usual auxiliary materials (hardener, wetting agent, etc.) are applied to the board surface. A melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 60 g resin fl./m ² , solids content: approx. 55% by weight).

Then 23 g of corundum/m ² (F 200) are sprinkled onto the surface using a spreading apparatus. A distance of approx. 5 m from the dryer allows the corundum to sink into the melamine resin. The plate then goes through a circulating air dryer.

A second melamine resin layer (solids content: 55% by weight) is then applied in an amount of 25 g/m ² . This also contains the usual auxiliary ingredients. A second melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 50 g resin fl./m ² , solids content: approx. 55% by weight). The plate is dried again in a circulating air dryer.

Following the drying process, a third melamine resin is applied again using a roller unit. The application quantity of the resin is approx. 20 g melamine resin fl./m ² (solids content: 61.5% by weight). In addition to the hardener and wetting agent, the recipe also contains a release agent. A third melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 40 g resin fl./m ² , solids content: approx. 55% by weight). Then approx. 6 g are spread using a spreading unit Glass balls / m ² scattered. These had a diameter of 60 - 80 µm. The board is again dried in a circulating air dryer and then coated again with a fourth melamine resin that contains cellulose (Vivapur 302). Approximately 20 g of melamine resin fl./m ² (solids content: 56.0% by weight) are again applied. 0.25 g cellulose/m ² is applied. A fourth melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 30 g resin fl./m ² , solids content: approx. 55% by weight). In addition to the hardener and wetting agent, the recipes also contain a release agent. The resin is again dried in a circulating air dryer and then the panel is pressed in a short-cycle press at 200 ° C and a pressure of 400 N / cm ² . The pressing time was 10 seconds. A pressed sheet metal with a wooden structure was used to provide structure.

For comparison, a plate was pressed in which the corundum was applied using a roller application. The amount of resin applied to this panel was approximately 20 g/m ² (solid) higher than the one on which the corundum had been sprinkled. In the first three commissioned works, recipes containing corundum were used. In the final commission, the melamine resin contained glass beads and cellulose. The application quantities of the two components were comparable to those of the spread plate. The application quantity was determined to be approx. 30 g corundum/m ² by gravimetric determination. The behavior of both samples against abrasion was determined in accordance with DIN EN 15468. The transparency of the surface was assessed visually. This resulted in the following values: 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 Stronger transparency disturbances in the wood pores and in the entire surface

Example 3:

In a large-scale test, 10,000 printed HDF (format: 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, approx. 70 g of melamine resin fl. (solids content: 55% by weight) containing the usual auxiliary materials (hardener, wetting agent, etc.) are applied to the board surface. A melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 60 g resin fl./m ² , solids content: approx. 55% by weight).

Then 23 g of corundum/m ² (F 200) are sprinkled onto the surface using a scattering apparatus. A distance of approx. 5 m from the dryer allows the corundum to sink into the melamine resin. The plate then goes through a circulating air dryer.

A second melamine resin layer (solids content: 55% by weight) is then applied in an amount of 25 g/m ² . This also contains the usual auxiliary ingredients. A second melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 50 g resin fl./m ² , solids content: approx. 55% by weight). The plate is dried again in a circulating air dryer.

Following the drying process, melamine resin is applied again using a roller unit. The application quantity of the resin is approx. 20 g melamine resin fl./m ² (solids content: 61.5% by weight). In addition to the hardener and wetting agent, the recipe also contains a release agent. A melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 40 g resin fl./m ² , solids content: approx. 55% by weight). Then approx. 6 g of glass balls/m ² are scattered using a spreading unit. These had a diameter of 60 - 80 µm. The panel is again dried in a circulating air dryer and then coated again with a melamine resin that contains cellulose (Vivapur 302). Approximately 20 g of melamine resin fl./m ² (solids content: 56.0% by weight) are again applied. 0.25 g cellulose/m ² is applied. A melamine resin is also applied to the underside of the board using a roller application unit (application quantity: 30 g resin fl./m ² , solids content: approx. 55% by weight). In addition to the hardener and wetting agent, the recipes also contain a release agent. The resin is again dried in a circulating air dryer and then the plate is placed in a Short cycle press pressed at 200°C and a pressure of 400 N/cm ² . The pressing time was 10 seconds. A pressed sheet metal with a wooden structure was used to provide structure.

For comparison, 10,000 panels were pressed in which the corundum was applied using a roller application. The amount of resin applied to this panel was approximately 20 g/m ² (solid) higher than the one in which the corundum was sprinkled. In the first three commissioned works, recipes containing corundum were used. In the final commission, the melamine resin contained glass beads and cellulose. The application quantities of the two components were comparable to those of the spread plate. The application quantity was determined to be approx. 30 g corundum/m ² by gravimetric determination. The behavior of both samples against abrasion was determined in accordance with DIN EN 15468. The transparency of the surface was assessed visually. This resulted in the following values: Sample exam Corundum scattered (after 10,000 pressings) Corundum roller application (after 10,000 pressings) Change in gloss level*) Measured -1 highlight point -4 highlights (Starting value: 15 highlights) Change in gloss level visual assessment No abnormalities Clearly visible wear on the pressed sheet metal corners *) The gloss level measurement was carried out using a gloss level measuring device from Dr. Long at a measuring angle of 60°, DIN EN 13 722: 2004-10

Claims (9)

1. Production line for carrying out a method for producing an abrasion-resistant wood material board which has at least one decorative layer, in particular a printed decorative layer, on the upper side;
   comprising

   - at least one first application device (1) for applying a first resin layer to the upper side and/or underside of the wood material board,

   - at least one device (10) arranged downstream of the first application device (1) in the processing direction for scattering a predetermined amount of abrasion-resistant particles; wherein the at least one scattering device (10) consists of a supply funnel, a rotating, structured scattering roller and a scraper,

   - at least one first drying device (1a) arranged downstream of the first application device (1) and scattering device (10) in the processing direction for drying the first upper and/or lower resin layer;

   - at least one second application device (2) arranged downstream of the first drying device (1a) in the processing direction for applying a second resin layer, to the upper side and/or underside of the wood material board,

   - at least one second drying device (2a) arranged downstream of the second application device (2) in the processing direction for drying the second upper and/or lower resin layer; and

   - at least one short-cycle press (5),

   wherein the production line further comprises a light barrier, and the at least one scattering device (10) is controllable by the light barrier,

   wherein the light barrier is arranged in front of the scattering roller provided in the scattering device in the processing direction.
2. Production line according to claim 1, characterized in that the at least one scattering device (10) comprises an oscillating brush system.
3. Production line according to claim 1, characterized in that at least one hopper for collecting excess abrasion-resistant particles is provided upstream of the scattering roller.
4. Production line according to claim 3, characterized in that the collection hopper is coupled to at least one conveyor and a screening device, wherein the excess abrasion-resistant material collected in the collection hopper is transported to the screening device via the conveyor.
5. Production line according to claim 4, characterized in that the screen meshes of the screening device correspond to the largest used grain of the abrasion-resistant particulate material.
6. Production line according to one of the preceding claims, characterized in that the at least one scattering device (10) is arranged in at least one booth provided with at least one means for removing dusts occurring in the booth.
7. Production line according to claim 6, characterized in that the means for removing the dusts is in the form of a exhaust device or also as a device for blowing in air by means of nozzles.
8. Production line according to one of the preceding claims, characterized by

   - at least one third application device (3) arranged downstream of the second drying device (2a) in the processing direction for applying a third resin layer to the upper side and/or lower side of the wood material board,

   - at least one third drying device (3a) arranged downstream of the third application device (3) in the processing direction for drying the third upper and lower resin layers;

   - at least one fourth application device (4) arranged downstream of the third drying device (3a) in the processing direction for applying a fourth resin layer, to the upper side and/or underside of the wood material board;

   - at least one fourth drying device (4a) arranged downstream of the fourth application device (4) in the processing direction for drying the fourth upper and lower resin layers; and

   - the at least one short-cycle press (5) arranged downstream of the fourth drying device (4a) in the processing direction.
9. Production line according to claim 8, characterized in that a scattering device (20) for scattering glass spheres followed by the third drying device (3a) is provided downstream of the third application device (3) in the processing direction.

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