METHOD FOR COATING A PLANAR WORKPIECE

Abstract

The invention relates to a method for coating a planar workpiece. In order to provide a planar workpiece, which is produced from a workpiece having lignocellulose fibers and a proportion of more than 50 wt % binding agent and optionally filler, with improved performance characteristics, a method is provided having the following steps: providing the planar workpiece, which has an upper face and a lower face and a lateral surface, applying a coating, applying a decoration, optionally structuring the coating, at least on a portion of an upper face, a lower face, or a lateral surface, in each case, and optionally curing the coating.

Claims

1. A method for coating a planar workpiece, wherein the planar workpiece is produced from a material having lignocellulose fibers and a proportion of more than 50 wt % melamine-formaldehyde resins, phenol-formaldehyde resins, methylene diphenylisocyanate (MDI), also in emulsified form as eMDI, polymeric diphenylmethane diisocyanate (PMDI), or mixtures of the aforementioned binding agents, comprising the steps of: providing the planar workpiece, which has an upper face and a lower face and lateral surfaces, applying a coating, and applying a decoration.

2. The method according to claim 1, wherein the coating is selected from the group consisting of heat-curable synthetic resins, varnishes, and hot melt.

3. The method according to claim 1, wherein the coating is applied as a liquid coating, as a particulate coating, in the form of papers, and/or in the form of films.

4. The method according to claim 1, wherein the coating is a single layer or multiple layers.

5. The method according to claim 1, wherein the coating is cured under the effect of pressure and/or temperature.

6. The method according to claim 1, wherein the coating is cured by radiation.

7. The method according to claim 1, wherein the structuring is created by mechanical or chemical means.

8. The method according to claim 1, wherein the coating is provided with aggregates.

9. A planar workpiece, produced from a material having lignocellulose fibers and more than 50 wt % melamine-formaldehyde resins, phenol-formaldehyde resins, methylene diphenylisocyanate (MDI), also in emulsified form as eMDI, polymeric diphenylmethane diisocyanate (PMDI), or mixtures of the aforementioned binding agents, wherein the planar workpiece has an upper face, a lower face, and lateral surfaces, wherein the upper face, lower face, or at least one lateral surface are at least in portions provided with a coating that have a decoration.

10. The planar workpiece according to claim 9, wherein a primer is applied between the workpiece and the coating or to a coating.

11. The planar workpiece according to claim 9, wherein an adhesive is applied between the workpiece and the coating.

12. The planar workpiece according to claim 4, wherein at least two lateral surfaces that are facing each other have a profile.

13. A use of the planar workpiece with a coating according to claim 9, as a floor covering, wall covering, ceiling covering.

14. The method according to claim 1, further comprising the step of structuring the coating, at least on a portion of an upper face, a lower face, or a lateral surface.

15. The method according to claim 1, further comprising the step of curing the coating.

16. The method according to claim 6, wherein the radiation is electron curing radiation or UV radiation.

17. The planar workpiece according to claim 9, wherein the coating has a structure.

Description

DETAILED DESCRIPTION

[0037] Details of the invention are explained in greater detail below using exemplary embodiments.

[0038] In the following, if a carrier board is coated as the workpiece, a carrier board is always meant that consists of 54 wt % melamine resin and 45 wt % wood fibers as well as 1 wt % paraffin. Depending on need, a higher or lower proportion of binding agent can be used, for example a proportion of 51 wt %, 52 wt %, 56 wt %, 58 wt %, or 60 wt % binding agent. The proportion of paraffin always remains the same. The proportion of wood fibers is adapted to the proportion of the binding agent in each case. The carrier board has a thickness of 8 mm. The thickness, however, can be chosen between, for example, 4 mm and 12 mm without difficulty; in particular cases or respectively for particular uses, a smaller or larger thickness can also be chosen. A carrier board with a thickness of 4.5 mm is also particularly typical. The carrier board is produced by mixing binding agent and fibers, scattering a fiber cake, and pressing in a press, wherein, as is typical, pressing plates or circulating metal belts act upon the upper and lower faces of the fiber cake or respectively of the planar material under pressure and at an increased temperature. For the following experiments, the carrier board has a large size of 2800 mm×2070 mm. For the exemplary embodiments described below, the carrier board is used as an uncoated board.

[0039] Optionally, the carrier board can be sanded before the coating is applied. The sanding loss per side is 0.1 mm to 0.15 mm; the total sanding loss is therefore 0.1 mm to 0.3 mm of the original total board thickness.

[0040] Insofar as ranges are indicated in the following for an exemplary embodiment, for example for decorative raw paper, the number of printing inks, or the amount of the varnish, synthetic resin, or hot melt used, we note that the invention can be carried out over the entire indicated range. The indication of a range simply shows the flexibility of the method according to the invention, or respectively the variety of coating possibilities of the workpiece according to the invention. The same applies to the indication of alternatives, for example for applying printing ink or ink or for applying coatings.

[0041] Insofar as the use of synthetic resin is described in the following, typically a synthetic resin is used that contains or can contain the usual auxiliary substances such as hardening agents, wetting agents, etc., which typically amount to 1 wt % to 5 wt % of the total amount of synthetic resin used.

Exemplary Embodiment 1

[0042] Carrier Board Pressed with Paper Assembly

[0043] A decorative paper and an overlay are placed onto the upper face of the carrier board, an optionally used backing is placed under the lower face of the carrier board, and this pressed material stack made of three or respectively four layers is pressed in a short-cycle press. The overlay, decorative paper, and the optionally used backing are each used as synthetic resin-impregnated papers.

[0044] For exemplary embodiment 1, a decorative paper is used as the impregnated paper for coating the carrier board with a total weight of 110 to 200 g/m.sup.2, based on [0045] a decorative raw paper with a weight of 50 to 90 g/m.sup.2, with [0046] a decorative overprint with 1 to 6 colors, produced from pigmented inks that are applied in an analog manner, for example by means of a printing roller, and/or in a digital manner, for example by means of an inkjet printer. The inks are water-based so they can be dried with warm air after being applied, or the inks can be UV-cured and can be cured with UV radiation after being applied. Furthermore, to produce the decorative impregnated paper, [0047] resin impregnation, performed before or after the printing, takes place on the basis of urea resin or melamine resin or a mix of the two resins, wherein the synthetic resin is applied as a liquid or as a solid, in particular in powder form. Then the synthetic resin is dried, but not yet cured, until it is present in state B with a weight of 60 g/m.sup.2 to 110 g/m.sup.2.

[0048] Furthermore, an overlay as an impregnated paper with a total weight of 120 to 400 g/m.sup.2 is used as a coating, based on [0049] a raw paper with a weight of 3 g/m.sup.2 to 70 g/m.sup.2, wherein light raw papers with a weight of 10 g/m.sup.2 to 25 g/m.sup.2 are preferably used, [0050] a resin impregnation on the basis of melamine resin, which is applied in watery form or as a solid, in particular in powder form, and which is present after drying in state B, meaning not yet cured, with a weight of 85 g/m.sup.2 to 280 g/m.sup.2, and [0051] a filling with corundum of specification F 180 to F 240 (according to the FEPA standard) in an amount of 5 g/m.sup.2 to 50 g/m.sup.2, preferably 10 g/m.sup.2 to 15 g/m.sup.2, wherein the corundum is either scattered or applied in a mixture with the synthetic resin.

[0052] Finally, a backing as an impregnated paper is optionally used with a total weight of 150 g/m.sup.2 to 240 g/m.sup.2, based on [0053] a raw paper with a weight of 70 g/m.sup.2 to 120 g/m.sup.2 [0054] a resin impregnation on the basis of urea resin and/or melamine resin or mixes of the two resins, which is applied in watery form or as a solid, in particular in powder form; present in state B with a weight of 80 to 120 g/m.sup.2.

[0055] Alternatively or in addition to a backing, footstep sound insulation, for example, a layer of paperboard or cardboard or EPS, can be attached to the lower face of the carrier board, typically by laminating, meaning by adhering the footstep sound insulation by means of an adhesive.

[0056] The further production of the coating on the workpiece takes place in that a pressed material stack is produced that has, from top to bottom, the overlay as an impregnated paper, the decorative paper as an impregnated paper, the carrier board, and optionally the backing as an impregnated paper. The pressed product stack is pressed in a short-cycle hot press to form a laminate, wherein the short-cycle press has an upper pressing plate that acts on the overlay and a lower pressing plate that acts on the lower face of the carrier board or the backing, and wherein the short-cycle press is adjusted as follows: [0057] under the effect of increased pressure of at least 25 kg/cm.sup.2 and increased temperature of 180° C. to 220° C., preferably 200° C., measured at the pressing plate, [0058] and a pressing time of 6 seconds to 30 seconds [0059] while forming a surface structure by means of the upper pressing plate, which optionally has a structure that is adapted at least in portions to the decoration (known as “embossed in register”).

[0060] The coated carrier board produced in this manner is also dimensionally stable under the influence of water; it does not swell and it also shows no deformation in the face, meaning no bending or distortion.

Exemplary Embodiment 2

[0061] A single- or multilayer varnish layer can be applied to the overlay, into which a structure is embossed according to the coated workpiece according to exemplary embodiment 1, in particular in order to adjust surface properties such as gloss, high gloss, or matte effect of the surface or to create anti-fingerprint properties. The varnish is preferably applied as a UV varnish, usually in two to three layers, wherein preferably in the case of multilayer varnish application, the already applied layer is partially set after each varnish layer is applied. After the last varnish layer is applied, the varnish layers cure completely. The adhesion of the varnish layer on the overlay can optionally be improved in that a primer is applied to the overlay before the varnish is applied.

[0062] A typical example of a varnish application onto an overlay takes place, for example, by means of a water-based varnish, known as hydro varnish, for example a UV-curable acrylic varnish. A first layer of the varnish of 10 g/m.sup.2 is applied to the surface of the overlay and partially sets. This layer acts as an adhesion agent between the synthetic resin of the overlay and the following varnish layers. To achieve, for example, a varnish coating with a total layer thickness of 50 g/m.sup.2, a second layer with 28 g/m.sup.2 of hydro varnish is applied to the first layer, followed by two additional layers with 5.5 g/m.sup.2 of hydro varnish each. After each layer, the applied varnish can partially set; after all the layers have been applied, the applied varnish is cured completely. The varnish can be applied in any manner, by pouring, spraying, rolling, or with a doctor knife.

[0063] Preferably, the varnish layering is supplemented with corundum with a diameter of preferably 1 μm to 5 μm, usually in the last layer or in the last two layers, in order to improve the scratch resistance of the varnish surface. Corundum is preferably scattered into a not yet cured varnish layer. The decoration is thus further developed by the embossed structure and further protected by the coating of varnish.

[0064] This method for varnish application on synthetic resin surfaces is suitable, for example, for creating laminates of the use classes 23 to 34 according to EN 16511. Afterwards, the coated carrier board is split into rectangular panels with a length of 1000 to 2800 mm and a width of 90 to 500 mm. Connecting means of a tongue-and-groove type are worked in on the panels on four lateral surfaces, which are optionally equipped with locking elements, for the formation of locking profiles with which adjacent panels are placed and locked in the horizontal and vertical directions in a floating bond (known as click panels), wherein connecting means and/or locking elements consist of the core material of the carrier board and for this purpose are carved out of it or wherein the locking elements are carried out as separate elements into which the locking profile is introduced and which are attached to the lateral surfaces of the carrier board.

[0065] The coated carrier board, which is produced in this way as a laminate, is water-resistant and dimensionally stable. It can be used inter alia as a floor, wall, or ceiling covering, as a structural element for indoor construction, as a structural element for outdoor construction, in vehicle construction, or to design a facade.

Exemplary Embodiment 3

[0066] Carrier Board with Laminated-on Layer Made of PVC

[0067] A layer of PVC as coating is laminated onto a carrier board as described above. For this purpose, an adhesive is applied to the upper face of the carrier board, for example in an amount of 60 g/m.sup.2 to 100 g/m.sup.2. To fix the layer of PVC, all hot-melt adhesives can be used; however, a polyurethane-based, water-resistant hot-melt adhesive is preferred. A layer of PVC, the outside of which is provided with a decoration, is placed with the inside onto the adhesive on the carrier board. The layer of PVC is usually between 1 mm and 5 mm thick.

[0068] The stack made up of the carrier board, adhesive, and PVC layer is pressed in a laminating press under the application of pressure and usually increased temperature until the hot melt adhesive has substantially developed its adhesive power.

[0069] A carrier board coated with PVC can be used, for example, as a water-resistant panel for a floor covering, but also for structures in outdoor construction, for example for facades or structural elements such as dividers or privacy shielding walls.

Exemplary Embodiment 4

[0070] Carrier Board with Liquid Overlay Including Decorative Direct Printing

[0071] A workpiece, in this case a carrier board that is coated with liquid synthetic resin, is produced, wherein beforehand a primer is applied to the carrier board and a decoration is then applied onto this primer using direct printing. The direct printing is then covered with layers of synthetic resin applied as a liquid, wherein corundum is introduced into a non-outer layer. The carrier board coated in this way is cured in a short-cycle press (SC press). Specifically, the coating from exemplary embodiment 2 is applied as follows: [0072] Priming the board with the aid of a melamine resin, a urea resin, or a mix of the two synthetic resins, applied in liquid form as a coating, in an amount of approx. 20 g/m.sup.2 to 30 g/m.sup.2 (solids content: melamine resin: approx. 65 wt %, urea resin: approx. 50 wt % of the total applied amount of synthetic resin). The application takes place using rollers. [0073] Drying the resin with the aid of an air-circulating dryer or IR radiators to a moisture content of approx. 20%. [0074] Repeatedly applying color primer (for example, mix of pigments and binding agent such as casein or corn protein) in liquid form in an amount of 5 g/m.sup.2 to 10 g/m.sup.2 each (solids content: approx. 50 wt %) with intermediate drying, for example by air circulation or IR radiators. The application of the color primer also takes place via roller application. The use of white pigments (titanium dioxide, calcium carbonate, barium sulfate) is preferred in this case. [0075] Applying a liquid primer, for example an isocyanate primer, in an amount of approx. 10 g/m.sup.2 to 20 g/m.sup.2 to improve the adhesion of the layers to be subsequently applied. The primer is dried by air-circulating dryers or IR radiators. A roller application is used again here. [0076] Printing a decoration onto the surface, the adhesion of which has been improved by the primer, either in an analog manner, for example by means of a roller, or in a digital manner, for example with an inkjet printer with water-based inks, then drying the ink by means of an air-circulating dryer, if necessary. [0077] Applying a sealant as a coating by means of roller application, wherein the liquid sealant consists of melamine resin (solids content approx. 65 wt %) and glass spheres mixed into it (diameter of glass spheres: 70 μm bis 90 μm). The application amount is 20 g/m.sup.2-30 g/m.sup.2. Then, the [0078] drying, but not curing, of the synthetic resin takes place using air circulation or IR radiators until the B-state is reached, followed by cooling and interim storage. [0079] Applying another coating made of liquid melamine resin in roller application in an amount of approx. 60 g/m.sup.2 to 80 g/m.sup.2 (solids content approx. 65 wt %) to the side of the board that is printed and already sealed by a layer of synthetic resin. [0080] Scattering corundum onto the not dried liquid melamine resin with the aid of a scattering device. The corundum has a grain size of F180 to F240 according to the FEPA standard. The amount is between 10 g/m.sup.2 and 50 g/m.sup.2 of corundum, depending on the desired wear resistance. [0081] Repeated application (preferably up to 5 layers) of a coating of melamine resin on the upper face of the board in an amount of 20 g/m.sup.2 to 40 g/m.sup.2 per layer, wherein the melamine resin has the solids content indicated above. During the application of the last layers, glass spheres (diameter: 70 μm bis 90 μm) are added to the resin. After each application, intermediate drying takes place with the aid of air circulation or IR radiators. [0082] In parallel with the coatings on the upper face, the application of a liquid melamine resin as a backing can also take place on the back side of the board. This can take place in a part of the roller application plants and, for example, reach a total amount of 100 g/m.sup.2 to 140 g/m.sup.2. The melamine resin has the usual solids content indicated above. In addition, the synthetic resin can also contain dye or pigment. Intermediate drying is also to be performed in this case, either by means of air circulation or by means of IR radiators. [0083] Then, the carrier board, coated on one or both sides, is pressed in a short-cycle hot press to form a laminate, as already described in exemplary embodiment 1, [0084] under the effect of increased pressure of at least 25 kg/cm.sup.2 and increased temperature of 200° C. [0085] and a pressing time of 6 to 30 s [0086] while forming a surface structure above the decoration; optionally adapted to each other, known as “embossed in register.”

[0087] If further machining of the coated carrier board is desired, this can take place in the same way as described in exemplary embodiment 1. The use of the coated carrier board or a panel produced from the coated carrier board can also take place in the same manner. The properties of the carrier board coated according to exemplary embodiment 4 are comparable to those of the coated carrier board according to exemplary embodiment 1.

[0088] For a carrier board with a coating according to this exemplary embodiment 4, a synthetic resin-impregnated paper can also be used as a backing instead of the synthetic resin applied as a liquid. Alternatively, a paperboard or a layer of EPS can also be fastened to the lower face of the carrier board by means of adhesive.

Exemplary Embodiment 5

[0089] Carrier Board with Hot Melt Cover Including Decorative Direct Printing [0090] Applying a white-pigmented polyurethane hot melt (PU hot melt) to the carrier board (application amount: approx. 60 g/m.sup.2 to 120 g/m.sup.2) in a liquid or respectively melted state as a coating. The hot melt is preferably applied in multiple layers of 5 g/m.sup.2 to 20 g/m.sup.2 each. The application takes place at a temperature of 120° C. as a liquid with the aid of a roller application plant onto the surface or upper face of the carrier board, which serves as the workpiece in this case. If necessary, the smoothing of the still liquid hot melt then takes place in a second application plant. The proportion of pigment in the PU formulation is approx. 20 wt %. [0091] Cooling of the surface [0092] According to a first alternative: Printing a white liquid color layer with a digital printer (application amount: 10 g/m.sup.2 to 20 g/m.sup.2), then optionally drying the color layer, for example, with an infrared or air-circulating dryer. [0093] Printing a decoration onto the surface with the aid of a digital printer using water-based or UV inks, then optionally drying the ink, for example, with a UV or air-circulating dryer. [0094] According to a second alternative: Placing a decorative paper impregnated with cured synthetic resin or a decorative paper film onto the still liquid hot melt and activating the adhesive in a laminating press under the effect of pressure and in most cases also increased temperature until the desired adhesive power is achieved. Temperatures of 80° C. to 150° C. and a pressure of 150 N/cm.sup.2 to 350 N/cm.sup.2 are typical. [0095] For both of the alternatives above: Applying another coating, in this case a non-pigmented, preferably transparent PU hot melt layer (application amount: 50 g/m.sup.2) with the aid of a roller application unit. [0096] Optional: Scattering corundum particles into the hot melt (grain size: F180 to F240 according to the FEPA standard) with the aid of a scattering apparatus (application amount: between 10 g/m.sup.2 and 50 g/m.sup.2, depending on the desired abrasion resistance). [0097] Application of another PU layer (application amount: approx. 30 g/m.sup.2) with a roller application unit. [0098] Cooling of the surface. [0099] Optional: Painting the surface with a UV varnish that contains approx. 30 g/m.sup.2 of nanoparticles made of corundum to improve the scratch resistance (varnish application amount: 10 g/m.sup.2 to 40 g/m.sup.2) with subsequent UV curing.

[0100] This coated carrier board can also be split into panels as described in exemplary embodiment 1 and provided with edge profiles. The use of the coated carrier board according to exemplary embodiment 5 and if applicable the panels produced therefrom is also described as in exemplary embodiment 1.

Exemplary Embodiment 6

Laminating on a Multilayer Plastic Film and Applying a UV Varnish

[0101] Coating a workpiece, in this case a carrier board, with a multilayer plastic film is described, the layers of which are connected to each other by adhesive or synthetic resin and which is connected to, for example, the upper face of the carrier board by an adhesive. The plastic film has a ready-to-use surface provided with a decoration. In addition, a UV varnish is applied as a sealant. On the opposite side of the carrier board, in this case the lower face, a backing is applied. The coated carrier board is produced by [0102] Applying a PU hot melt to the lower face of the carrier board in an amount of approx. 100 g/m.sup.2 with the aid of a roller application plant [0103] Placing a backing consisting of a thin laminate, a multilayer plastic film, or a multilayer synthetic resin-impregnated paper onto the PU hot melt. [0104] Pressing the backing in a laminating press. The laminating press, which is also used in the following laminating processes, is at temperatures of 80° C. to 160° C. and at a pressure of 150 N/cm.sup.2 to 350 N/cm.sup.2. The laminating can take place, for example, at approx. 120° C. at 300 N/cm.sup.2 and a pressing duration of 0.8 seconds [0105] Rotating the carrier board coated on the lower face [0106] Applying approx. 100 g/m.sup.2 of a PU hot melt as a coating to the upper face of the carrier board with the aid of a roller application plant [0107] Applying a multilayer decorative plastic film or a multilayer synthetic resin-impregnated paper, which are in each case made from an inner core layer and an outer decorative film, in this case, however, without a wear layer as a coating on the layer of PU hot melt, which is applied to the upper face of the carrier board, then [0108] Pressing the film in a laminating press, which is designed as a continuous press, within the pressing conditions mentioned above, in the present case approx. 120°, at 300 N/cm.sup.2 and a pressing duration of 1 second, [0109] Applying a coating made of multiple layers (usually 2 to 5 layers) of UV varnish, wherein the non-outer layers contain corundum to increase the wear resistance and nanoparticles (e.g., Aerosil) to increase the scratch resistance, wherein preferably the particles for increasing the scratch resistance are applied in a varnish layer that is closer to the outside of the coating. [0110] Partially setting the individual varnish layers after each application and final curing after the last application with UV or EBH radiators, as already described above in other exemplary embodiments.

[0111] This coated carrier board can also be split into panels as described in exemplary embodiment 1 and provided with edge profiles. The use of the carrier board coated according to exemplary embodiment 6 and if applicable the panels produced therefrom is also described as in exemplary embodiment 1.

Exemplary Embodiment 7

Laminating on CPL/HPL

[0112] Exemplary embodiment 7 is similar to exemplary embodiment 6, but instead of the decoration, the decorative paper, or the decorative film as the coating, a thin laminate (CPL or HPL) provided with a decoration is applied to the workpiece, which has a wear layer. The coating can thus take place without the application of varnish. The following takes place: [0113] Roller application of a PU hot melt in an amount of approx. 100 g/m.sup.2 to the lower face of the board [0114] Placing a backing consisting of a thin laminate, a plastic film, or a paper onto the lower face of the workpiece, in this case the carrier board [0115] Pressing the backing in a laminating press, which can be adjusted as described above in exemplary embodiment 6, in this case a continuous press, at approx. 120° C., 300 N/cm.sup.2 and a pressing duration of approx. 1 second [0116] Rotating the carrier board [0117] Roller application of a layer of a PU hot melt in an amount of 100 g/m.sup.2 to the upper face of the board [0118] Placing the CPL or HPL thin laminate provided with a decoration, which laminate meets, for example, the requirements of EN 13329 for the use classes 23 to 32 [0119] Pressing the assembly in the laminating press at approx. 120° C., a pressure of 300 N/cm.sup.2, and a pressing duration of 1 second

[0120] If further machining of the workpiece, in this case the coated carrier board, is desired, this can take place in the same way as described in exemplary embodiment 1. The use of the coated carrier board or a panel produced from the coated carrier board can also take place in the same manner. The properties of the carrier board coated according to exemplary embodiment 7 are comparable to those of the coated carrier board according to exemplary embodiment 1.

Exemplary Embodiment 8

[0121] Carrier Board with Synthetic Resin Coating and Varnishing

[0122] Using a glue (e.g.: PVAc glue, urea-based glue, etc.), a decorative finish film is laminated onto the carrier board as a coating on the upper face and a backing is laminated onto the lower face. The finish film provided with a decoration has a paper weight of approx. 80 g/m.sup.2 and bears a decorative printing, and the backing has a paper weight of approx. 60 g/m.sup.2; the finish film and backing are each impregnated with synthetic resin, for example melamine. To fix the finish film and the backing, in each case a glue amount of approx. 60 g/m.sup.2 is applied to the carrier board in liquid form before the finish film or respectively the backing are placed.

[0123] The lamination takes place in a continuous press at a temperature of approx. 160° C., a speed of 20 m/min, and a pressure of 300 N/cm.

[0124] After the glue has cooled and hardened, a corundum-containing EBH varnish is applied to the finish film as a coating (EBH: electron beam hardening) in an amount of approx. 90 g/m.sup.2 (corundum content: approx. 15 wt %). The varnish was partially set with a UV radiator. The EBH sanding base (application amount: approx. 80 g/m.sup.2) was then applied and partially set with an EBH radiator. After that, approx. 20 g of a topcoat filled with nanoparticles was applied as a coating to improve the scratch resistance. All applications took place with the aid of roller units. The complete assembly was then hardened with another EBH radiator.

[0125] The product met the requirements of DIN EN 14978 class 33.

Exemplary Embodiment 9

[0126] Carrier Board with a Varnish-Based Coating

[0127] A first prepreg is laminated onto a carrier board on the upper face. The first prepreg is a paper impregnated with transparent, tinted but still transparent, or semitransparent varnish or with colored, usually opaque varnish, which paper has been preimpregnated by drying or respectively curing the varnish. For laminating, first a hot melt is applied to the carrier board, then the first prepreg is placed, and then the carrier board and the first prepreg are guided through a laminating system that fixes the first prepreg to the carrier board by means of the hot melt with the conditions mentioned in exemplary embodiments 4 or 5. If tinted or colored varnish is used, the carrier board shows a uniform surface colored in the manner of a primer, on which a decoration applied over it is particularly well displayed.

[0128] Onto this carrier board provided with a prepreg, a second prepreg is placed as an additional coating, which also consists of a paper that is impregnated with a varnish and is optionally printed with a decoration. Optionally, a primer is applied in order to optimize the adhesion of the second prepreg on the first prepreg. A sanding base, for example, can be applied, meaning a varnish that allows an additional coating to be applied without sanding. The second prepreg is fixed to the first prepreg by laminating, in the same way as described for the first prepreg. Alternatively, the second prepreg can be fixed to the first prepreg by a solvent-containing adhesive.

[0129] An at least single-layer, preferably, however, multilayer varnish coating is now applied to the carrier board coated with the first and the second prepreg. Typically, two or three varnish layers are applied. Optionally, a primer can be applied to the second prepreg in order to improve the bonding of the varnish layer to the prepreg. Alternatively, the varnish introduced into the second prepreg and the subsequently applied varnish layer are matched to each other such that the varnish layer adheres well to the varnish of the second prepreg.

[0130] Optionally, footstep sound insulation is applied to the lower face of the carrier board.

Exemplary Embodiment 10

[0131] Carrier Board with Veneer

[0132] A carrier board according to the invention is coated either only on the upper face or on the upper and lower faces with a veneer made of oak. If a veneer is only applied to the upper face, a backing is advantageously applied to the lower face to prevent a deformation of the board.

[0133] An adhesive that fixes the veneer due to its adhering effect or a binding agent, in this case preferably a partially cross-linked binding agent, is introduced between the veneer and the carrier board.

[0134] The partially cross-linked binding agent is advantageously a synthetic resin, advantageously a thermosetting plastic, in particular an aminoplast; preferably, the binding agent has melamine resin, for example as melamine-formaldehyde resin. The binding agent can be used in an amount that is just sufficient to fix the veneer to the upper or respectively lower face of the carrier board. Preferably, the binding agent is used in excess so that the binding agent penetrates into the veneer, possibly penetrates through it. The binding agent can optionally be introduced in the form of a paper impregnated with binding agent. The paper can be symmetrically impregnated with binding agent or an excess of binding agent can be applied to at least one side of the paper. The binding agent is used to impregnate the paper in liquid form and is subsequently dried in a partially cross-linked state. It can alternatively also be used partially in a solid state, for example as powder or dust, that adheres to the still liquid, partially cross-linked binding agent that impregnates the paper. The binding agent can alternatively also be applied directly to the veneer or the upper or respectively lower face of the carrier board.

[0135] The veneer is fixed to the carrier board by means of a press. If adhesive is used to fix the veneer, a vacuum press, for example, that is known per se can be used for fixing.

[0136] If binding agent is used to fix the veneer, a short-cycle press, for example, can be used in which the synthetic resin is subsequently cross-linked at temperatures of 100° C. to 240° C. and a pressure of 25 N/mm.sup.2 to 50 N/mm.sup.2 within 20 seconds to 60 seconds so that it is cured.

[0137] In this case, the synthetic resin, which is liquid during the cross-linking, penetrates at least partially into the veneer; optionally, in particular if an excess of binding agent is used, the binding agent penetrates through the veneer at least in portions. According to a preferred alternative, so much excess binding agent is used that the synthetic resin completely penetrates through the veneer and forms the outer surface of the coating of the carrier board. At the mentioned pressure, the veneer is typically also compressed. When a binding agent is used, the veneer is more pressure-resistant after the pressing and offers a less delicate surface than a non-compressed veneer.

[0138] In the same way as a binding agent, a polyurethane prepolymer (PU prepolymer) can alternatively be used for direct application onto the surface of the carrier board or the veneer. By curing the PU prepolymer to form a polyurethane, the veneer is bound to the carrier board. Due to the improved light fastness in comparison to aromatic isocyanates, an aliphatic isocyanate is preferred as the polyurethane prepolymer; if yellowing or discoloration is not a concern, an aromatic isocyanate can also be used as the polyurethane prepolymer. The veneer and the carrier board can be pressed together under the pressing conditions mentioned above for the binding agent, for example in a short-cycle press.

[0139] An additive can be applied to the surface of the binding agent facing the veneer. The additive can influence, for example, color, conductivity, or light fastness. Additives can also be used in combination with each other. If the additive is applied to the surface of the binding agent, the additive is conveyed through the veneer during the cross-linking in the press by the then liquefied binding agent to the degree that the binding agent penetrates through the veneer. In this way, a maximum effect is achieved with low use of additive.

[0140] The carrier board that is coated in this way with a veneer can be coated further, in particular be sealed against the influence of moisture, for example the veneer can be painted.

[0141] If the binding agent forms the surface of the veneered carrier board or if a sealant is subsequently applied to protect against moisture, then the water-resistant carrier board can be used with a decorative, still water-resistant coating in damp rooms, for example as a floor covering or for furniture, in particular bathroom or kitchen furniture, or to equip saunas or swimming pools.