EP1722985B1 - Decorative paper comprising electrically charged fibres - Google Patents

Description

The invention relates to a method and an apparatus for the production of a paper having an abrasion-resistant surface and to a paper produced according to the method.

The US 4,940,503 discloses a method in which abrasion resistant particles are optionally sprinkled onto a melamine resin impregnated overlay or onto a melamine resin impregnated decor paper. Overlay and decorative paper are then pressed together so that a decorative paper with abrasion-resistant surface results. However, the abrasion resistance that can be achieved with such a process is relatively low compared to other processes. It must be made separately an overlay, so a paper.

The WO 00/44984 A1 discloses a method in which a special dispersion containing abrasion resistant particles such as corundum or silicon carbide is sprayed onto a decorative paper. The decorative paper is in turn used in the manufacture of a laminate floor panel. With the help of this method, it is indeed possible to achieve high abrasion values. However, the expenditure on equipment is comparatively high in comparison to the scattering of abrasion-resistant particles. It will be understood by those skilled in the art that when the decorative paper is to be crimped with a panel, the abrasion-resistant particles applied to the decorative paper to protect a press are covered with an overlay, for example, to produce panels for a laminate floor or worktop with an abrasion-resistant surface.

The WO 00/44576 A1 discloses another method in which abrasion-resistant particles such as corundum are scattered on the impregnated decor paper. Subsequently, fibers are applied together with resin and the layer system is pressed. In this way If a separate production of decorative paper should be avoided. However, it is problematic to provide in this way a protective layer that comes close to the positive properties of an overlay paper. The above-mentioned problems are solved by the subject-matter of the independent claims of the present invention. It is an object of the invention to provide an abrasion-resistant paper with improved properties.

The object is achieved by a method in which abrasion-resistant particles are applied to a paper. Subsequently, fibers are electrostatically charged. When loaded, the fibers are applied to the paper. In this way, it is relatively easy to bring fibers arranged on the paper. The fibers are then completely or predominantly perpendicular to the paper. A regular distribution of the fibers can be achieved. This results in a paper in which abrasion-resistant particles are applied to the surface. Furthermore, on the side with the abrasion-resistant particles, perpendicular fibers are located on the paper surface.

In order to apply the fibers to the paper in the electrically charged state, for example, a scattering roller is provided, which is supplied with electrical charge. The scattering roller has recesses on its surface into which the fibers pass. The recesses preferably have an irregular shape and are distributed irregularly on the surface of the roller. The fibers are brought from above onto the spreader roll. The scattering roller is preferably made of electrically non-conductive material such as plastic or rubber, so as to be able to bring electric charge from the roller to the fibers, rotates the roller, so eventually the fibers fall from the roller. Below the roller, the paper with the abrasion-resistant particles is then passed over. The fibers thus fall on the paper and stand up vertically.

If the paper is then pressed in a press, the perpendicular fibers lay over the abrasion-resistant particles. The press is so reliably protected from damage.

In particular, such a press is used as a press in which pressing is effected by means of circulating belts or rollers. In this case, the paper enters the press together with plates from one side. The vertical fibers are then bent uniformly in one direction. This results in a uniform, protective surface. The paper compressed with a plate is moved out of the press at a different location. The paper-provided plate has an abrasion-resistant surface. The product thus produced can now serve as a worktop. If necessary, the plate is sawn into individual elements having a predetermined, desired size. The individual elements can now be provided laterally with coupling elements, so as to provide panels for a floor covering.

The paper is usually provided with a decor, for this purpose, the paper may be printed with a pattern. The abrasion-resistant particles are then located on the decor, ie on the printed surface. The paper is brought into the press with the plate so that the decor is visible. The material of the fibers is then chosen so that this practically does not prevent the view of the decor.

The fibers can be made of polyester. On the one hand, it is possible to apply electrical charge to the fibers. On the other hand, a decor remains visible through these fibers.

Although polyester has the desired properties for the aforementioned purpose. Disadvantageously, this material is relatively expensive.

In order to be able to produce more cost-effectively, cotton linters are therefore preferably used. These are very short fibers that are produced and extracted from cotton and can not be spun. This waste product can also be electrically charged. It can be provided a transparent protective layer, so that a decor of an underlying paper remains visible.

The length of the fibers can be at half a millimeter. However, the fibers can be two to four millimeters long.

To ensure that the fibers get evenly from the roller to the paper, they are advantageously brushed out of the recesses of the scattering roller out. For this purpose, an additional roller, which is provided with bristles, is provided laterally next to the spreading roller. This bristled roller also rotates, brushing the fibers out of the recesses of the spreader roller.

To assure the desired dosage, a squeegee acts on the spreader roll in an embodiment that retains excess spilled fiber. It thus reaches the predetermined amount of fibers on the paper.

During the scattering of fibers, funnels are preferably provided laterally of the paper in order to be able to collect excess fibers and to be able to feed them back to the scattering roller, etc. This recycling saves costs.

Paper-applied or applied electrically-charged fibers are provided in one embodiment with a resin, preferably with melamine resin, so as to provide further desired surface properties. Desirable is regularly insensitivity to staining and chemical resistance, also protects melamine resin the surface particularly good against moisture.

In one embodiment of the invention, the abrasion-resistant particles are sprayed onto the paper together with resin, Such a method is basically from the WO 00/44984 A1 known. The paper is previously advantageously impregnated with a resin, in particular with a melamine resin or a mixture of a melamine resin and a urea resin so as to improve the adhesion of the abrasion-resistant particles to the paper. Advantageously, excess resin is returned to the container in which the abrasion-resistant particles are with the resin. The recycling of the resin saves on the one hand costs, but more important is that the return of the resin creates a flow in the container. This flow contributes to keeping the abrasion-resistant particles in suspension, thus ensuring an improved uniform distribution of the particles in the resin. In this way, even relatively large abrasion-resistant particles can be processed.

If the abrasion-resistant particles have been sprayed onto the paper together with the resin, this is advantageously dried in one embodiment of the invention. By drying one molecule enlargement, namely a polycondensation is achieved, so it creates a first layer on the paper, Now if electrically charged fibers are applied to this first layer, so the fibers can not penetrate into this first layer, Would the fibers in this penetrate first layer, they are so far no longer available for the desired protection of a press. The pre-drying thus contributes to the fact that the fibers develop the desired protective effect.

According to the invention, abrasion-resistant particles are sprinkled on impregnated decor paper in an alternative advantageous embodiment. In particular, the abrasion-resistant particles are coated with a bonding agent prior to spreading in order to achieve good abrasion values. Subsequently, electrically charged fibers are placed on the decorative paper.

The paper is suitably impregnated with a resin, preferably with the aid of metering rollers. Alternatively, the impregnation can be carried out with a doctor blade. With the help of the resin or by the impregnation abrasion-resistant particles are fixed on the paper.

By sprinkling the abrasion resistant particles succeeds in comparison to the spray process, as it from the WO 00/44984 A1 is known, a more even distribution of abrasion resistant material. Also, the equipment cost is lower. The wrapping of the particles with a bonding agent is very easy, since the particles only have to be temporarily immersed in a corresponding bath. This is technically much less expensive compared to the apparatus, which according to the WO 00/44984 A1 is required.

In order to be able to meter the abrasion-resistant particles particularly reliably, the particles provided with the adhesion promoter are preferably dried before being sprinkled. In the dried and thus particularly well dosed state of the adhesive coat the abrasion-resistant particles in particular completely, so as to achieve very good abrasion. The abrasion-resistant particles are first dipped for this purpose in a liquid, the Alternatively, the abrasion-resistant particles are sprayed with the primer, this is still less expensive compared to the effort, which according to the WO 00/44984 A1 to operate, since it does not have to be paid attention to dosage and circulation. Subsequently, the particles are dried and are now particularly suitable for use. The dried, provided with a primer abrasion-resistant particles are sprinkled on the paper, and in particular on a decorative paper. Preferably, a roller is used for the spreading, which is provided with recesses, which in particular run unevenly, the depth of the recesses, however, is substantially maintained. The provided with the adhesion promoter abrasion-resistant particles are scattered from above the roller and thus get into the wells. Excess material, that is to say excess, abrasion-resistant particles provided with an adhesion promoter, is stripped off by means of a doctor blade. Subsequently, the rotating roll passes to a brush, which removes the abrasion-resistant particles provided with a bonding agent.

The brush is preferably a circulating roller provided with bristles so as to uniformly sweep out the particles provided with an adhesive. In this way, the abrasion-resistant particles are scattered uniformly on the decor paper, preferably with an amount of 18 to 25 g / m ² , depending on the desired abrasion class, the grain size is preferably 90 to 130 μ m in diameter. If the diameter chosen smaller, so a relatively large amount of abrasion-resistant particles is consumed together with adhesion promoter. If the diameter is chosen to be larger, the abrasion-resistant particles may damage the press despite a protective layer of fibers.

Before the paper is sprinkled with the abrasion-resistant particles, the respective webs are passed in an advantageous embodiment, in particular by a melamine resin or a mixture containing melamine resin. By means of the adhesion promoter it is possible to incorporate the abrasion-resistant particles, for example corundum particles or silicon carbide, into the resin matrix. Otherwise, an optically visible interface between the abrasion-resistant particles and the resin or the resin matrix may remain, resulting in graying. If no adhesion promoter is used, the abrasion-resistant particles can be torn out of the matrix, which leads to low abrasion values.

If the paper with the applied abrasion-resistant particles as well as with the applied, electrically charged fibers with a further layer, such as a plate pressed, the surface temperature during the pressing is preferably 180 to 185 ° C. Typically, pressures of 20 to 35 bar are used. The specified temperature is advantageous for the resin material to harden. Said pressure is advantageous in order to keep the water which contains the layer system in liquid form. Otherwise it would escape in gaseous form and thereby produce a rough surface. The high pressure also ensures a very homogeneous surface.

Particularly preferably, the decorative paper has a mass of 20 to 60 g / m ² , so as to be able to manage with small amounts of resin. The decorative paper is advantageously filled with acrylate or an acrylate-containing dispersion so as to be able to further reduce the amount of relatively expensive melamine resin required for the impregnation. The acrylate or the dispersion is pressed into the decorative paper, in particular from both sides, so as to ensure that it passes into the interior of the paper.

The WO 02/079 571 A1 discloses suitable compositions and a method for bringing the acrylate or, for the purposes of the present invention, the dispersion into the interior of the paper,

During the spreading of abrasion-resistant particles, funnels are preferably provided laterally of the paper in order to be able to absorb excess abrasion-resistant particles. This catfish succeeds in recycling the abrasion-resistant particles, as far as they have been scattered laterally in excess.

In particular, corundum or aluminum oxide particles to be scattered are provided with an adhesion promoter, since materials such as silicon carbide can be installed relatively easily in a resin matrix anyway. Silicon carbide, however, has the disadvantage over corundum or aluminum oxide that it is dark particles, which are clearly visible especially in bright decors. As a rule, silicon carbide is therefore less suitable for optical reasons.

When impregnating decorative paper is typically provided with 100 to 120 wt .-% resin based on the decorative paper. Thus, if the basis weight of the decor paper is, for example, 100 g / m ² , then 100 to 120 g of resin is used. If, however, decorative paper with a weight of only 30 g / m ² is provided and is, or an acrylate-containing dispersion was pressed into the paper, an acrylate, the amount of resin required for the impregnation can be wt .-% reduced to 45 to 55,

Instead of melamine resin and mixed resins can be used. Typically, such a mixed resin may consist of 70 to 80% by weight of urea resin and 20 to 30% by weight of melamine resin so as to lower the cost of the resin, decorative paper is preferably impregnated with a mixed resin because it can save costs,

The result is a decorative paper, in which corundum lies in a plane. when abrasion-resistant particles have been sprinkled on the paper. This can be determined with the microscope, In addition, the then advantageously provided adhesion promoter can be found in the finished product, which wraps the abrasion-resistant particles,

It is preferred as adhesion promoters on a silane-based, because these primers are particularly well suited to adhere on the one hand on the corundum or alumina and on the other hand with the resins used to bring about the desired adhesion and thus the desired abrasion resistance,

In principle, other adhesion promoters have been disclosed. However, an amino-silane coupling agent has proven particularly suitable.

Fig. 1:

Vorrichtung zum Aufstreuen von abriebfesten Partikeln auf ein Papier;

Fig. 2:

hergestelltes Papier;

Fig. 3:

Paneel mit hergestelltem Papier,

Show it:

Fig. 1:

Apparatus for spreading abrasion-resistant particles on a paper;

Fig. 2:

manufactured paper;

3:

Panel with manufactured paper,

Abrasion-resistant particles 1 of corundum having a diameter of 90 to 130 μ m were coated with a silane coupling agent and dried, the abrasion-resistant particles 1 are now in a free-flowing condition and are scattered onto a roll 2 as the FIG. 1 clarified in cross-section. The roller 2 has recesses not shown on the surface. By the slow rotation of the roller 2 in the counterclockwise direction along the arrow 3, the scattered particles reach a squeegee 4, which bears against the roller 2 with an open end. The squeegee 4 ensures that the abrasion-resistant particles 1 uniformly and completely Fill wells. From here, the abrasion-resistant particles to a fast-rotating brush 5 on transported, which rotates in the example in the clockwise direction in the direction of arrow 6. The abrasion-resistant particles are thus completely removed from the depressions and thus arrive dosed on the surface of a decorative paper 7. The decorative paper 7 is guided by means of suitably rotating rollers 8 and 9 below the roller. The decorative paper 7 was impregnated immediately before with a mixture of 25 wt .-% melamine resin and 74 wt .-% urea resin. The decorative paper has a basis weight of 30 g / m ² and inside acrylate. The resin application during impregnation is 15 g per square meter of paper.

It succeeds in spreading the paper particularly evenly with abrasion-resistant particles. The abrasion-resistant particles 1 adjoin to the side with the printed decor.

Subsequently, fibers 10, which may be impregnated with a melamine resin, as previously scattered the abrasion-resistant particles 1 on the decorative paper. It is used a device that in FIG. 1 comprises components shown. However, the components involved in this process step such as roller, brush and squeegee then consist of electrically non-conductive materials such as rubber or plastic, The involved components such as roller, squeegee and / or brush are additionally charged with electrical charge, this has the consequence that When the fibers are brushed out of the waltz to be electrostatically charged, the fibers are accelerated towards the paper. The repulsive effect causes the fibers to be evenly distributed on the paper. They align parallel to each other and are substantially perpendicular to the paper.

To carry out the method, a relatively large amount of resin is preferably used when applying the abrasion-resistant particles in comparison to the application of the particles by spraying especially when fibers are applied that have not been provided with a resin. Based on the basis weight of the paper in the dry (raw) state, typically 100 to 250% by weight are applied when spraying the mixture containing the resin and the abrasion-resistant particles. In the present case, the amount of resin in an embodiment of the invention becomes therefore chosen so that the dry paper is provided with a layer whose weight is 2 to 2.5 times or even more,

When the electrically charged fibers 10 have been applied to the paper, the paper is desirably dried. It is such a paper ready, which is provided on the one hand with abrasion-resistant particles and which is on the other hand prepared to be used in a press. In the FIG. 2 the basic structure is shown.

The decorative paper 12 thus provided with an abrasion-resistant layer is then pressed, for example at pressures of 30 bar and temperatures of 180 ° C., with a base plate 13 made of HDF and a backing paper 14. The hitherto completely or predominantly substantially vertically projecting fibers lie over the abrasion-resistant particles 1. A press is thus protected from damage by the abrasion-resistant particles.

Subsequently, panels of the desired size of typically 20 to 40 cm in width and a length of typically 80 cm to 160 cm are sawed out and laterally provided with coupling means such as groove 15 or spring 16. Preferably, tongue and groove have further locking means, not shown, which can positively connect two panels with each other so that there is a locking parallel to the surface of the panels. Such locks are for example from the WO 02/079 571 A1 known.

The countertraction paper has in particular a low basis weight of 20 to 60 g / m ² and is preferably provided with acrylate and impregnated with a urea resin or a mixture containing predominantly urea resin prior to compression. In this way, the cost of applying the Gegenzugpapiers is minimized because comparatively little and also relatively inexpensive resin is used. The countertape paper protects a panel or countertop, etc. from distortion,

Claims (13)

1. Method for the production of paper having an abrasion resistant coating and fibers, which are mounted onto or at the abrasion resistant coating, wherein abrasion resistant particles (1) are applied on a paper together with resin (11) characterized in that the fibers (10) are electrically charged and applied onto the coating consisting of abrasion resistant particles and the resin (11).
2. Method according to the preceding claim, wherein the paper provided with the fibers (10) is subsequently dried.
3. Method according to one of the two preceding claims, wherein a mixture of resin (11) and abrasion resistant particles is sprayed onto the paper and excess resin (11) is recirculated from the paper to the container in which the abrasion resistant particles and the resin are located, wherein after the spraying and before the application of fibers, the paper with the applied layer is dried.
4. Method according to one of the preceding claims, wherein the paper is impregnated with resin (11) and wherein the abrasion resistant particles (1) are provided with an adhesion promoter and are spread.
5. Apparatus for performing a method for the production of a paper with an abrasion resistant surface according to one of the preceding claims by means which are characterized in that the fibers are charged by said means and the charged fibers are applied onto the paper by said means, comprising a rotatable roller (2) having recesses and a brush (5) arranged on a side next to the roller, which is arranged such that the recesses may be swept out, as well as means to electrically charge the roller and/or the brush, as well as rotatable rollers (8, 9), with which a paper web (7) can be moved underneath the roller (2) having the recesses.
6. Apparatus according to the preceding claim, characterized by means to spread abrasion resistant particles onto the paper, in particular comprising a further rotatable roller (2) having recesses and a further brush (5) arranged on the side next to the further roller, which is arranged such that the recesses may be swept out, as well as means (8, 9, 8', 9') with which the paper web can be moved underneath the further roller.
7. Paper having an abrasion resistant coating consisting of abrasion resistant particles (1), resin (11) and fibers (10), which are mounted onto or at the abrasion resistant coating producible according to a method according to any one of the claims 1to 4, wherein the fibers (10) are mounted perpendicular with respect to the surface of the paper (7) in or on the abrasion resistant coating characterized in that the fibers (10) consist of polyester and/or cotton and/or that cotton linters are used as fibers (10).
8. Paper according to the preceding claim, characterized in that the abrasion resistant particles (1) are enclosed by an adhesion promoter.
9. Paper according to one of the preceding claims 7 to 8, characterized in that the particles (1) have a diameter from 50 to 200 µm, preferably from 90 to 130 µm.
10. Paper according to one of the preceding claims 7 to 9, characterized in that the abrasion resistant particles (1) are enclosed by a silane adhesion promoter, preferably by an amino-silane adhesion promoter.
11. Paper according to one of the preceding claims 7 to 10, characterized in that the particles (1) consist of aluminum oxide, particularly preferred of corundum.
12. Paper (7) according to one of the preceding claims 7 to 11, wherein the paper has a weight of 10 to 60 g/m², particularly preferred of 20 to 40 g/m², wherein the inside of the paper (7) is filled with acrylate or an acrylate containing dispersion.
13. Paper (7) according to one of the preceding claims 7 to 12, which is impregnated with a resin mixture which contains an amino resin, as well as an additional resin, namely in particular an urea resin and which is provided with a décor, wherein the paper with the fibers (10) is mounted onto a board, preferably wherein a counteracting paper is mounted underneath the board.

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