EP3578383A1 - Method for refining a large format building panel - Google Patents

Abstract

A method for finishing a large-format construction panel (1) made of a wood material, in particular MDF or HDF, with a top (2) and a bottom (9), with a relief being embossed at least in the top (2) and then on the embossed A decoration is applied to the top (2) and sealed by applying an abrasion-resistant layer (4), with the following steps: a) a coating agent is applied to the top (2), b) at least in the areas in which the relief is to be embossed , the top (2) is treated with superheated steam to achieve a surface temperature of 30 to 50 ° C, c) after the superheated steam treatment, a decorative paper (3) is applied to the top and an overlay paper (4) is applied to the decorative paper (3), i.e. ) the underside (9) is provided with a counter-tension (8), e) the structure so widespread is fed to a short-cycle press (30) and pressed together under high pressure and temperature, f) during the Ver Pressing, the relief is embossed as at least one strip-shaped recess (5) with two opposite side walls (5.1, 5.2) and a bottom wall (5.3) connecting these in the top (2) with a depth (T).

Description

The invention relates to a method for finishing a large-scale provided building board, in particular MDF or HDF, with a top and bottom, wherein at least in the top of a relief is impressed, and then applied to the embossed top of the building board a decor and the decor then by Applying an abrasion resistant layer is sealed.

Such a method is for example from the EP 1 820 640 B1 known.

Such structural panels are divided after finishing in individual panels and used for example as a floor or as wall and ceiling panels and are often provided with a wood, stone or fantasy decoration with superimposed, three-dimensional surface. The split panels have connecting means (tongue and groove) and are usually equipped with locking means for locking adjacent plates in the horizontal and vertical directions (so-called click panels). The superimposition of decor and three-dimensional surface creates a realistic visual and haptic impression of the imitated material.

In particular, in the case of floor panels, it is known that these are coated at least on the upper side and have a structure adapted to the decor. Such a structure is referred to as a decore-synchronous structure (embossed register). The decor is present either as a paper layer laminated onto the carrier plate or as a color layer printed directly onto the carrier plate. The decor is also provided with a wear-resistant layer. For this purpose, either abrasion-resistant paper layers, so-called overlays, or after curing abrasion resistant paint or resin layers are used. The decorsynchrone structure is present as a three-dimensional surface structure and is by means of a corresponding impressed three-dimensionally structured press plate into the plate surface. The thermal and pressure-activatable constituents of the coating melt and run out and fill the three-dimensional structure embossing with hardening. The structure usually has a height of up to 500 μm. The number and the depth of the structures are limited on the one hand by the available amount of activatable components and on the other by the pressing force.

In laminate flooring, the abutting edges adjacent adjacent floor panels encounter are problematic. Depending on the incidence of light, even the smallest differences in height cause visually unsightly shadow formations that adversely affect the overall appearance of a floor. Due to the core of wood-based material, the panels are also sensitive to moisture. Liquid spilled on the floor must be wiped away as quickly as possible to prevent the liquid from penetrating into the joint between the abutting edges. Penetrates water, the wood fibers in the support plate can expand and produce irreversible swelling, as destroyed by the swelling pressure of the wood, the structure and / or the adhesive is partially hydrolyzed. For this reason, it is important that even during the production of the panels, the later edges are given special attention. Adjacent panels should be able to rest against each other, it should give a visually uniform appearance to a floor laid panels and care must be taken that spilled liquid can not flow immediately into the joints.

Starting from this problem, the method described above should be improved accordingly.

1. a) auf die Oberseite wird ein Vergütungsmittel aufgetragen,
2. b) zumindest in den Bereichen, in denen das Relief geprägt werden soll, wird die Oberseite zur Erreichung einer Oberflächentemperatur von 30 bis 50 °C mit Heißdampf behandelt,
3. c) nach der Heißdampfbehandlung wird auf die Oberseite ein Dekorpapier und auf das Dekorpapier ein Overlaypapier aufgebracht,
4. d) die Unterseite wird mit einem Gegenzug versehen,
5. e) der so verbreitete Aufbau wird einer Kurztaktpresse zugeführt und unter hohem Druck und hoher Temperatur miteinander verpresst,
6. f) während des Verpressens wird das Relief als mindestens eine streifenförmig ausgebildete Vertiefung mit zwei gegenüberliegenden Seitenwandungen und einer diese verbindenden Bodenwandung in die Oberseite mit einer Tiefe eingeprägt.

In order to avoid the aforementioned disadvantages, it is provided according to the invention in a generic method that the following steps are carried out:

1. a) a topping agent is applied,
2. b) at least in the areas in which the relief is to be embossed, the upper side is treated with superheated steam to achieve a surface temperature of 30 to 50 ° C,
3. c) after the superheated steam treatment, a decorative paper is applied to the upper side and an overlay paper is applied to the decorative paper,
4. d) the underside is provided with a counter-pull,
5. e) the so-widespread structure is fed to a short-cycle press and pressed together under high pressure and high temperature,
6. f) during the pressing, the relief is embossed as at least one strip-shaped recess with two opposite side walls and a bottom wall connecting them in the top with a depth.

Along the embossed depressions is later the division of the large format plate into individual panels. Due to the embossed depressions then the top is lowered at the side edges. The abutting edges of adjacent panels are therefore lower in relation to the upper side. Height offset can not cause shadowing in such a case, which attracts attention because all butt joints are lowered. By a corresponding edge profiling a firm connection between adjacent panels can be achieved, whereby the too rapid penetration of liquid is effectively avoided in the butt joint.

In order to be able to lower the side edges of the panels circumferentially, preferably at least one further recess extending at an angle transversely to the at least one depression is embossed. Here, too, a plurality of transverse depressions are preferably impressed, along which the division of the panels can then take place in the transverse direction.

If a MDF or HDF board is used as a building board, it is provided that their density profile (density profile over the cross-section of the plate) compared to a conventional density profile, as for example from the EP 3 023 261 B1 is known, is lowered. When pressing the fiber cake to a building board of desired thickness results in the largest density in the top and bottom of the plate. Due to the heat input during pressing, a pressing skin forms at the top and the bottom, which is also called "rotting layer". The plate, when pressed with a maximum apparent density in the cover layers of 950-1000 kg / m ³ , can be provided without press-coating, that is, the press skin is not removed. But it is also possible to reduce the density at the top of the press skin at least partially, for example, to a thickness of 0.3 mm, grind.

By means of the tempering agent it is achieved that the previously reduced bulk density at the upper side (in the cover layer) is increased again in order to achieve sufficient strength properties on the later panels.

When embossing the at least one depression, a surface temperature of up to 220 ° C is established.

If desired, one or more paper layers can be applied under the decorative paper as an underlay. These paper layers are soaked like the decor paper with a melamine resin.

The topping agent (melamine resin) fixes the compacted fiber cake during pressing and hardening and increases the bulk density in the top layer.

The depth of the at least one depression is preferably up to 0.7 mm and may in particular be stepped so that the bottom wall is step-shaped. In such a case, several first pressing steps are carried out with different pressing depths.

In order to be able to align the building board during the subsequent further processing steps, markings may be printed on the decorative paper where it comes to rest in the bottom walls of the at least one depression, which may consist of lines, circles, points, crosses or other graphic signs. Preferably, lines are used. Instead of imprinted markings, markings can also be embossed during the pressing, which marks are transferred to the building board as matt or shiny areas or geometric figures with the aid of the upper press plate. Such markings may also be provided on the edge of the decorative paper, so that they are located on the outer edge of the coated building board.

In addition, a structure can be impressed in the upper side over the upper press plate, which structure runs at least partially synchronously with the décor, which is called "embossed register" in technical language.

Figur 1

- eine perspektivische Teildarstellung einer großformatigen Bauplatte;

Figur 2

- die Draufsicht auf die Bauplatte nach Figur 1;

Figur 3

- eine schematische Teildarstellung vor dem zweiten Prägeschritt;

Figur 4

- eine vergrößerte Teildarstellung während des zweiten Prägeschrittes;

Figur 5

- eine schematische Darstellung der in der Kurztaktpresse befindlichen Bauplatte;

Figur 6

- ein übliches Rohdichteprofil einer HDF-Platte;

Figur 7

- das Rohdichteprofil einer ersten großformatigen Bauplatte;

Figur 8

- das Rohdichteprofil einer zweiten großformatigen Bauplatte;

With the aid of a drawing, an embodiment of the invention will be described in more detail below. Show it:

FIG. 1

- A partial perspective view of a large-sized building board;

FIG. 2

- The plan view of the building board after FIG. 1 ;

FIG. 3

a schematic partial representation before the second embossing step;

FIG. 4

- An enlarged partial view during the second embossing step;

FIG. 5

a schematic representation of the building board in the short-cycle press;

FIG. 6

a usual density profile of an HDF board;

FIG. 7

the density profile of a first large-format building board;

FIG. 8

- The density profile of a second large-sized building board;

The starting point is a large-format HDF board with a length of 2,800 mm or 1,860 mm, a width of 2,070 mm and a thickness of 7 mm to 14 mm. The bulk density is lowered compared to a conventional HDF board as a comparison of FIG. 6 with the FIGS. 7 and 8th shows. To form a weak cover layer, which can be plastically deformed, the cover layer tips were lowered compared to the standard by at least 40 kg / m ³ . Good results were achieved with a reduction of up to 60 kg / m ³ . The apparent density is then in the range of 950 to 1000 kg / m ³ . An example of the density profile of a conventional HDF board is in FIG. 6 shown. FIGS. 7 and 8th show examples of gross density profiles of structural panels used in the invention.

The HDF board can be provided without any brushes, ie with the complete press skin. Preferably, however, the press skin is abraded to a thickness of about 0.3 mm in order to deliberately "weaken" the top layer first.

First, as a tempering agent, 10 to 50 g / m ² , preferably 30 g / m ^{2 of} aqueous melamine resin is applied. It may be a standard impregnating resin having a solids content of 50 to 65 wt.%, Preferably 60 wt.% Act. In addition to water as a solvent other additives, such as hardener, wetting agents and the like may be present in the recipe. Alternatively, it is also possible to use UF resin as the tempering agent or UF and melamine resins in mixtures. Either a postforming resin or a standard impregnating resin that is more elasticized by the addition of flexibilizing agents (e.g., 1,4-butanediol, caprolactam, polyglycol, etc.). A subsequent addition of the elastification agent should be on the order of about 3 to 7 wt.%. In order to impress depressions 5, 6 in the top 2 of the structural panel 1, this is then heated to a temperature of 30 ° C to 50 ° C by order of 10 to 30 g / m ^{2 of} water vapor.

After this pretreatment, one or more resin-impregnated paper layers as underlay 4.1 (cf. FIG. 5 ) and then then or only alone (cf. FIG. 3 ) a decorative paper 3 launched. The decorative paper 3 can be monochrome or multicolored. On the decorative paper 3 marks 7 may be provided. The marks 7 may be circles 7.1, crosses 7.2, lines 7.3 and lines 7.4 or other geometric figures. By means of these markings 7, the building board 2 can be aligned via a camera system for carrying out further processing steps.

Subsequently, a backing sheet 8 is placed on the underside 9 of the building panel 1 and an overlay paper 4 on the decorative paper 3 as an abrasion-resistant layer. This structure is then fed to a short-cycle press 30, the upper press plate 31 is provided with strip-shaped elevations 32. The building panel 1 is aligned via the markings 7 and a camera system so that the elevations 32 emboss the recesses 5, 6 during the pressing of the construction and thereby form parallel and planar side walls 5.1, 5.2 and the bottom wall 5.3. Between the strip-shaped Ridges 32, the press plate 31 may be provided with an engraving over which during pressing in the top of the overlay, a structure is stamped, which is at least partially aligned in synchrony with the decor (embossed register).

The pressing time in the short-cycle press 30 is between 10 and 30 seconds, preferably 12 to 15 seconds, in which the resins melt and connect to the building board 1. The temperature of the press plates 31, 33 is up to 200 ° C. The pressure curve is carried out starting from a pressure build-up phase in a holding phase and a pressure reduction phase. The embossing depth T will be carried out in the sense of a path control.

For a useful embodiment, at least two recesses 5, 6 in the longitudinal direction L and two in the transverse direction Q must be embossed, so that the side edges of the divided panels are all lowered.

LIST OF REFERENCE NUMBERS

1

building board

2

top

3

decor

4

abrasion-resistant layer / overlay paper

4.1

underlay

5

deepening

5.1

sidewall

5.2

sidewall

5.3

bottom wall

6

deepening

7

mark

7.1

circles

7.2

cross

7.3

line

7.4

stroke

8th

return

9

bottom

30

Short-cycle press

31

upper press plate

32

strip-shaped elevation

33

lower press plate

α

corner

L

longitudinal direction

Q

transversely

T

depth

Claims (15)

Method for finishing a building board (1) provided in large format from a wood material, in particular MDF or HDF, with a top (2) and a bottom (9), wherein at least in the top (2) a relief is embossed and then on the embossed top (2) a decoration is applied and sealed by applying an abrasion-resistant layer (4), comprising the following steps: a) a topping agent (2) is applied to a tempering agent, b) at least in the areas in which the relief is to be embossed, the upper side (2) is treated with superheated steam to reach a surface temperature of 30 to 50 ° C, c) after the superheated steam treatment, a decorative paper (3) is applied to the upper side and an overlay paper (4) is applied to the decorative paper (3), d) the underside (9) is provided with a counter-pull (8), e) the so widespread structure is fed to a short-cycle press (30) and pressed together under high pressure and high temperature, f) during the pressing, the relief is embossed as at least one strip-shaped recess (5) with two opposite side walls (5.1, 5.2) and a bottom wall connecting them (5.3) in the top (2) with a depth (T). A method according to claim 1, characterized in that at least one further at an angle (a) transversely to the at least one recess (5) extending recess (6) is impressed. A method according to claim 3, characterized in that longitudinal recesses and / or a plurality of transverse recesses (6) are impressed. A method according to claim 1 or 2, characterized in that the building board (1) is an HDF board whose top (2) is still provided with a press skin. A method according to claim 3, characterized in that the press skin has a thickness of 0.3 to 0.5 mm. Method according to one of the preceding claims, characterized in that the bulk density of the building board (1) in the top layer (2) forming the cover layer is between 950 and 1000 kg / m ³ . Method according to one of the preceding claims, characterized in that the tempering agent is an aqueous melamine resin. A method according to claim 1, characterized in that at least 10 g / m ^{2 of} water vapor are applied. Method according to one of the preceding claims, characterized in that the depth (T) of the at least one recess (5, 6) is up to 0.7 mm. Method according to one of the preceding claims, characterized in that the depth (T) is stepped. Method according to one of the preceding claims, characterized in that markings (7.1, 7.2, 7.3, 7.4) are embossed on the bottom wall (5.3) of the at least one depression (5, 6). Method according to one of the preceding claims, characterized in that prior to the application of the decorative paper (3) at least one resin-filled cellulose layer is applied as an underlay (4.1). Method according to one of the preceding claims, characterized in that in addition to the relief, a structure is impressed, at least partially in synchronism with the decor. Method according to one of the preceding claims, characterized in that the embossing of the at least one recess (5) by means of a deep-structured pressing plate (31), preferably by means of strip-shaped elevations (32) on the press plate (31) takes place. Method according to one of the preceding claims, characterized in that the large-sized building board (1) is divided into individual panels, by in each case a saw cut is carried out in and along the recesses (5, 6).

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