A method of finishing a wood material board

The invention relates to a method for finishing a wood material board with a top and a bottom by a layer of liquid synthetic resin is at least on the top or bottom first applied, then at least one impregnated with a synthetic resin paper sheet is placed and this structure then in a press is pressed under high pressure and high temperature, the resin melts and bonds with the wood material board.

Such a method is known for example from EP 2743094 A1. With the synthetic resin coating on top of the carrier plate is to be achieved that only one side impregnated decorative paper can be used, because applied to the carrier plate liquid resin dissolves the pre-dried impregnating agent on the back of the decorative paper, so that a more rapid adhesion of the decorative paper is carried on the carrier plate. Prior to application of the decorative paper, the liquid-coated resin layer on the top surface must be dried.

a carrier layer of paper is first applied to the top of the features disclosed in the DE 10 2007 012 236 B4 wood material board. This backing layer is a decorative layer and then applying a sealing layer of lacquer to the decorative layer. The resist layer is then fully cured by means of electron beams and in the resist layer, a structure is embossed.

individual panels are cut from a so processed large-sized laminate board then, can serve as a floor, wall or ceiling covering. The panels can be provided at their side edges with a tongue / groove joint. A problem with laminates with a paper structure, the delamination is encountered wherever materials in layers with the addition of binder,

CONFIRMATION COPY

Heat and pressure are combined. Delaminations are often outwardly visible as bubbles or the paper layer peels off at a panel at the edges of the plate.

To exclude delamination, one is occasionally passed to coat plates directly.

DE 197 51 115 A1 discloses a method for coating a panel, in which on the surface of at least one color layer is applied by a printing process, especially by screen printing. The surface can be untreated ground or pretreated, in particular lacquered. Finally, the applied ink layer can be covered by a coating of clear lacquer.

In DE 10 2004 026 739 A1 describes a method, in which applied to the upper side of the wood material board, a primer by means of a roller and dried. a first and second lacquer layer is applied to the dried primer then applied which hardens under the action of UV light, wherein the curing is not completed. a UV-curable topcoat is finally applied to the first two paint layers and the uppermost layer of lacquer then plastically deformed. Direct printing is very expensive and must be done very carefully to avoid inclusions in the pressure build-up. It is also important that each individual layer is sufficiently dried before the next layer is applied in liquid form to avoid the merging of colors.

In the application of direct printing technology, so the direct printing of the individual layers on a support plate, also seen in the results compared to conventionally manufactured panels a reduction in thickness of the finished laminate panels by the omission of the paper plies. This leads to problems in continuous production when the large-coated laminate plates are then divided to produce the panels. In order to ensure that individual panels from falling out through the thickness of undersize from DIN 13329, a high quality assurance must be operated, which slows down the one hand, the manufacture and on the other hand, further increases the manufacturing costs. Ultimately, it comes to an irritation from the merchants and / or end-user, as the stack height directly coated plates coated with layers of paper plates differs visible.

In the known panel manufacturing HDF board or MDF-plates are used as support plate normally whose top is ground off by about 0.3 mm. At the top and bottom of the carrier plate, a pressing skin is formed, which is also called press or patina Ver-rottungsschicht. This press skin is formed during pressing of the fiber cake and is produced by the hot surface of the press plates or bands of the press. The press skin has a thickness of about 0.3 mm. Since the skin is completely compressed and about 0.1 mm from the core material to reduce the surface roughness on top of the plate abraded prior to further coating, the plates must be made thicker by a corresponding grinding allowance, which infiuenced the manufacturing sustainable. To prepare a standard-compliant, prepared by means of direct printing technology flooring laminate having a thickness of 6.0 mm, the carrier plate must be at least 0.61 mm.

In EP 2236313 is described for example in that the press skin must be ground because in their area of ​​heat input during the hot pressing is so high that the adhesive cures too quickly, Leimbrücken least break partly and make the coated layer prone. This breaking of the Leimbrücken makes finished panels susceptible to withdrawals of the applied on the carrier plate decorative and abrasion resistant layers. This delamination that up already at normal load and from the typical wooden materials magnitude can fundamentally occur from climate fluctuations are tolerated by the customer.

There is therefore a great need for abrasion-resistant laminate panels, located within the above-mentioned standard thickness tolerances are. Further, there is a need for a resource-saving process for the preparation, wherein the extra cost of additional process steps and / or are largely avoided by additional materials.

Starting from this problem is to be improved, a method for finishing a wood material board that is coated with at least one paper layer, that a strong connection between the paper layer and the upper surface of the wood particle board is manufactured, so that delamination can be reliably avoided. The aim is possible by a common impregnated paper can be used.

The problem solution is carried out with a generic method in that the top and / or bottom is also provided with a pressing skin and are provided unpolished and the layer is applied is so thin that the liquid synthetic resin fully retracts into the pressing skin, no active drying of the layer and the paper sheet is placed on the press skin.

It has been found, very surprisingly, this resin order, which is known per se from the direct printing technology, this results in the adhesion of the paper layer on the top and / or bottom of the wood material is plate substantially improved. Since the paper is a decorative paper usually is impregnated with a synthetic resin, one might assume that these better adhesion occurs only because more resin is used in the lamination. But this assumption is not correct, because known Delaminierungserscheinungen even

occur if the decorative paper is impregnated saturated with resin, and a paper is used, which is very absorbent, the entry of resin into the laminate structure thus is thereby increased. Delaminations can not be reliably prevented a configuration with that.

Tests have shown that no partial dissolution of the resin with which the paper sheet is impregnated, occurs, as is done in EP 2743094 A1. The fully retracted into the press skin resin is inactive here.

The improved adhesion is probably due to the fact that the top and / or bottom plate finish, ie untreated and will be provided with the full press skin available. The liquid applied resin penetrated into this press skin and thus, together with the press skin an optimal basis for the later applied decorative paper.

The liquid resin can be rolled, brushed on, sprayed or troweled.

the production process is accelerated, and also realizes a significant energy savings through the elimination of the active drying.

Preferably, the liquid synthetic resin is used in an amount of 5 to 100 g / m 2 , in particular 5 to 50 g / m 2 and more especially preferably 5 to 25 g / m 2 applied.

The resin is preferably a melamine resin or a urea resin or a melamine-urea resin mixture.

Good results have been realized with a coating, wherein the. Ratio of resin to water (60:40) with a tolerance of ± 10%.

The resin may contain additives, in particular contain curing agents and / or wetting agent and / or thermoplastic polymers.

The paper layer is preferably covered before pressing with a wear protective layer of resin. This anti-wear layer can be produced by a cloth soaked with a synthetic resin overlay paper. The paper layer is preferably in decorative paper. but the wear-resistant layer can be applied in liquid form. It is also conceivable, to scatter for the wear layer resin particles on the paper layer.

The refined by the present process the wood material board corresponds to a conventional laminate with paper buildup on the top side, with the main difference that the adhesion between the paper structure and the wood panel by the previously applied liquid resin layer is markedly improved. The wear protective layer can thus comprise abrasion-resistant particles such as corundum, in order to increase the abrasion resistance of the laminate. During the pressing of the laminate structure in the wear protection layer, a structure can be impressed. This structure may correspond to the decor to be ( "Embossed"). The decor may be a wood grain, or a mirror tiles. In the case of the wood grain, the structure corresponds to the shape of the grain, the knot holes or pores in the depicted wood surface. In the case of a mirror tiles the structure meets the joints.

The improvement achieved compared to a conventional laminate structure with layers of paper can easily be seen with reference to FIGS. These each showing a density profile of a coated MDF board from the upper surface (0 mm) to the center of the wood material core (3 mm).

Figure 1 shows the laminate structure with a standard MDF board whose top surface is ground to complete removal of the pressing skin. A resin impregnated decorative paper sheet and then an overlay paper layer is laid and pressed on the ground upper side. The peel strength of the cover layer is 2.0 ± 0.1 N / m 2 . The high bulk density of 1900 kg / m 3 results at the top by the paper structure. The middle of the wood material core, the density continuously decreases.

In the example shown in Figure 2 graph a standard MDF board was used with rough top surface, so an MDF board with complete Press skin were placed on a resin impregnated decorative and overlay paper layer and pressed. The abrasion resistance of the coating layer is 1, 5 ± 0.3 N / m. The bulk density is lower here at the top, but it is also formed by the paper layers. The bulk density initially decreases continuously, the increase was about 0.25 mm depth resulting from the pressing skin that was not removed from the top. Here is the Delaminierungsgefahr because the connection between paper construction and wood panel is bad.

When tested according to Figure 3 plate is an inventively treated standard MDF-plate provided with press-polished upper surface is provided and a 50 g / m 2 melamine resin was coated, before a synthetic resin-impregnated decorative paper and overlay paper layer were placed and pressed. The abrasion resistance of the coating layer was 1, 9 ± 0.1 N / mm 2 . It can be seen that the maximum density achieved almost the value of the standard plate (Figure 1), this but then decreases continuously and although the press skin is not removed, no increase in density more can be observed. As can be seen from a comparison of Figures 2 and 3, the flaw, which can lead to Dela Mini e approximately phenomena could be largely avoided, so that a largely closed curve is established. The deck schichtabhebefestigkeit moved to some half the level of the standard structure of Figure 1, it should however be borne in mind that the production time but is significantly reduced only in that the grinding of the pressing skin deleted, a cost saving is achieved and that the abraded region of the upper side does not have to be compensated by the introduction of more material in the manufacture of MDF-board in advance. It is apparent that the present invention is a Delaware Minie-tion is reliably prevented and, perhaps, the resin coating of the impregnated paper layers can be reduced because möglichicherweise that is necessary for the connection resin is supplied in advance by the resin entry into the press skin. The base can be refined as well as the top of the wood panel. Also, the top and bottom can be treated identically. Preferably, the finishing of both sides is then carried out simultaneously.

claims

1. A method for finishing a wood material board with a top side and a bottom side, by first a layer is applied from liquid resin to at least the top or the bottom, then at least one impregnated with a synthetic resin layer of paper is applied and this structure then in a press under high pressure and high temperature is pressed, wherein the synthetic resin melts and bonds to the top or the bottom of the wood material board, characterized in that the top and / or bottom is also provided with a pressing skin and are provided unpolished and the layer is applied as thin in that the liquid synthetic resin fully retracts into the pressing skin, no active drying of the layer and the paper layer is placed on the pressing skin.

2. The method according to claim 1, characterized in that both the top and the bottom is refined same.

3. The method of claim 1 or 2, characterized in that the liquid synthetic resin is rolled, smoothed, troweled or is sprayed on.

4. The method according to claim 1, characterized in that the

Resin in an amount of 5 to 100 g / m 2 is applied.

5. The method according to claim 4, characterized in that the synthetic resin in an amount of 5 to 50 g / m 2 is applied.

6. The method according to claim 5, characterized in that the synthetic resin in an amount of 5 to 25 g / m 2 is applied.

7. The method according to any one of the preceding claims, characterized in that the synthetic resin is a melamine resin or a urea resin or a melamine-urea resin mixture.

8. The method according to any one of the preceding claims characterized Ge, that the ratio of resin to water

(60:40) is a tolerance of ± 10%.

9. The method according to any one of the preceding claims, characterized in that the synthetic resin contains additives.

A method according to claim 9, characterized in that the resin hardener and / or wetting agent and / or thermoplastic Po contains mers.

11. The method according to any one of the preceding claims, characterized in that the at least one paper layer is a decorative paper.

12. The method according to any one of the preceding claims characterized Ge, that the paper layer before the pressing with a

Wear protection layer is covered resin.

13. The method according to claim 12, characterized in that an overlay paper is superposed on the paper sheet.