ES2952870T3 - Procedure for refining a provided build board - Google Patents

Abstract

A method of finishing a large format construction board (1) made of a wood material, in particular MDF or HDF, with a top (2) and a bottom (9), a relief being engraved at least on the top (2). and then a decoration is applied to the lid (2) on the relief and sealed by applying an abrasion-resistant layer (4), with the following steps: a) a tempering agent is applied to the lid (2), b) at least in the areas where the relief is to be stamped, the upper face (2) is treated with superheated steam to reach a surface temperature of 30 to 50 °C, c) after the treatment with superheated steam, a decorative paper (3) is applied to the upper face and an overlay paper (4) is applied to the decorative paper (3), that is, the lower face (9) is provided with a counterpull (8), e) the structure so widely used is fed to a short cycle press (30) and pressed together under high pressure and high temperature, f) during pressing the relief becomes at least one depression formed in the form of a strip (5) with two side walls opposite (5.1, 5.2) and a lower wall (5.3) that connects them is engraved on the upper part (2) with a depth (T). (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Procedure for refining a provided build board

The invention relates to a method for developing a provided construction board, in particular MDF (Medium Density Fiberboards) or HDF (High Density Fiberboards), with a top side and a lower side, where a relief is embossed at least on the upper side, and subsequently a decoration is applied to the upper embossed side of the construction board and the decoration is subsequently sealed by applying an abrasion resistant layer, with the following steps:

(a) a decorative paper is applied to the upper side and a paper is applied superimposed on the decorative paper as an abrasion-resistant layer, (b) the lower side is provided with a support, (c) the structure thus extended is introduced into a short cycle press and is pressed at pressure and temperature, (d) during pressing, the relief is embossed on the upper side to a depth as at least a band-shaped recess with two opposite side walls and a lower wall that the connect.

A method of this type is known, for example, from document WO 2016/180643 A1.

Document EP 1820640 B1 describes a procedure for the development of an MDF construction board supplied in large format, on the upper side of which a structure or relief is embossed, a decoration is applied to the embossed upper side and the decoration is then sealed with an abrasion resistant layer.

Document EP 3023261 B1 discloses a method for perfecting a wood-based board having a top side and a bottom side by first applying a layer of liquid synthetic resin to at least the top side or the bottom side, then applying at least one layer of paper impregnated with a synthetic resin, and subsequently pressing this structure in a press at high pressure and high temperature, whereby the resin melts and joins the wood-based board.

After further development, these construction boards are divided into individual panels and used, for example, as floor panels or as wall and ceiling panels, and are often provided with a wood, stone or fantasy decoration with a three-dimensional overlay surface. . Split panels have connecting means (tongue and groove) and are usually equipped with locking means for interlocking adjacent panels in horizontal and vertical directions (so-called click panels). The overlay of decoration 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 decoration. Such a structure is called a decoration-synchronous structure (relief register). The decoration is present as a layer of paper laminated on the support board or as a layer of paint printed directly on the support board. The decoration is also provided with a wear-resistant coating. For this purpose, abrasion-resistant layers of paper, called overlays, or, after curing, layers of abrasion-resistant lacquer or resin are used. The synchronous decoration structure is available as a three-dimensional surface structure and is embossed on the board surface by a corresponding three-dimensional structure pressing plate. In this, the coating components that can be activated thermally and under pressure melt and melt and fill the embossed three-dimensional structure upon curing. The structure is usually up to 500 μm high. The number and depth of the structures are limited, on the one hand, by the available quantity of activatable components and, on the other hand, by the pressing force.

In the case of laminate floors, butt edges where adjacent floor panels abut are problematic. Depending on the incidence of light, even the smallest differences in height cause visually unsightly shadow formations that negatively affect the overall appearance of a floor. Due to the wood-based material core, the panels are also sensitive to moisture. Liquid spilled on the floor must be cleaned as soon as possible to prevent it from penetrating the joint between the butt edges. If water penetrates, the wood fibers of the support board can expand and cause irreversible swelling, since the pressure due to swelling of the wood destroys the structure and/or the adhesive partially hydrolyzes. For this reason, it is important to pay special attention to the rear butt edges already during panel manufacturing. Adjacent panels must be able to rest firmly against each other, there must be a visually uniform appearance to a floor of installed panels and precautions must be taken to ensure that spilled liquid cannot immediately flow into the connecting joints.

DE 102008 008 240 A1 discloses a support board on the upper side of which water is applied before coating, which penetrates and causes a vapor shock during subsequent pressing, whereby the upper layer heats up very quickly. Heat and humidity cause better plastic deformability and therefore allow deeper pressed sheet structures to be embossed. Moisture also improves heat transfer from the short cycle press plates to the wood board.

Document EP 3059020 A1 describes the treatment of a wood-based board with water vapor, which can have a temperature of up to 60°C. This treatment aims to produce a moisture level of the board substrate as uniform as possible in order to improve priming for printing. To do this, first sand the moistened upper side and then preheat it to a temperature of about 45°C. Next, a first layer of resin is applied as a primer base. A white primer is applied on this base.

Document EP 2106903 A1 discloses a procedure for applying wear-inhibiting particles to a flat substrate, which is characterized in that the application is carried out by means of an electrostatic field with a potential difference of at least 10 kV.

Based on this problem, the procedure described at the beginning must be improved accordingly.

To avoid the aforementioned drawbacks, according to the invention, a conventional procedure provides that the following steps are carried out before applying the decorative paper:

e) a quenching and tempering agent is applied to the upper side,

f) at least in the areas where the relief is to be embossed, the upper side is treated with superheated steam to achieve a surface temperature of 30 to 50°C.

The large-format board is subsequently divided into individual panels along the embossed recesses. Embossed rabbets then recess the top side at the side edges. The butt edges of the adjacent panels are therefore lower than the top side. In such a case, the height shift cannot cause shadows that are visually noticeable because all butt joints are recessed. Corresponding edge profiling can be used to achieve a firm bond between adjacent panels, effectively preventing liquid from penetrating the butt joint too quickly.

In order to be able to recess the lateral edges of the panels perimeter, preferably at least one other recess is embossed that extends at an angle transversely to the (at least one) recess. Preferably, several transversely extending recesses are also embossed, along which division of the panels in the transverse direction can then be carried out.

If an MDF or HDF board is used as a building board, its bulk density profile (density path over the cross section of the board) is expected to be reduced compared to a typical bulk density profile, as known, for example, by document EP 3023261 B1. When the fiber cake is pressed to form a building board of the desired thickness, the greatest bulk density occurs in the area of the top and bottom side of the board. Due to the heat input during pressing, a pressed skin is formed on the upper and lower side, which is also called "decomposition layer". If the board has been pressed with a maximum apparent density in the face layers of 950 - 1000 kg/m3, unfinished pressing can be supplied, that is, without removing the pressing skin. However, it is also possible to polish the pressing skin at least partially, for example up to a thickness of 0.3 mm, in order to reduce the density on the upper side.

The quenching and tempering agent ensures that the previously reduced bulk density on the top side (in the top layer) is increased again in order to achieve sufficient strength properties in the back panels.

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

If desired, one or more layers of paper can be applied as an underlay under the decorative paper. Like decorative paper, these paper layers are impregnated with a melamine resin.

The tempering agent (melamine resin) applied to the top side fixes the compacted fiber cake during pressing and curing and increases the apparent density in the top layer.

The depth of the at least one recess is preferably up to 0.7 mm and, in particular, may be stepped, so that the bottom wall has a stepped shape. In this case, several pressing steps are carried out with different pressing depths.

In order to align the construction board during subsequent processing steps, markings may be printed on the decorative paper where it contacts the lower walls of the at least one recess, which may consist of lines, circles, dots, crosses or other signs. graphics. Lines are preferred. When pressing, instead of printed marks, raised marks can also be made, which are transferred to the construction board as matte or glossy areas or geometric figures with the help of the upper pressing plate. Such markings may also be provided on the edge of the decorative paper, so as to be located on the outer edge of the coated construction board.

Additionally, by means of the upper pressing plate, a structure can be embossed on the upper side, which is at least partially synchronous with the decoration, which in technical terminology is called "embossed register".

An example embodiment of the invention will be described in more detail below with the aid of a drawing. This shows:

Figure 1 - a partial perspective representation of a large format construction board;

Figure 2 - a top view of the construction board according to Figure 1;

Figure 3 - a partial schematic representation;

Figure 4 - an enlarged partial representation;

Figure 5 - schematic representation of the construction board on the short cycle press;

Figure 6 - a usual bulk density profile of an HDF board;

Figure 7 - the apparent density profile of a first large format construction board;

Figure 8 - the apparent density profile of a second large format construction 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 reduced compared to a typical HDF board, as shown by comparing Figure 6 with Figures 7 and 8. To form a weak top layer that can be plastically deformed, the peaks of the top layer were reduced by at least 40 kg/m3 compared to the norm. Good results were obtained with a reduction of up to 60 kg/m3. The apparent density is then between 950 and 1000 kg/m3. An example of the apparent density profile of a conventional HDF board is shown in Figure 6. Figures 7 and 8 show examples of bulk density profiles of construction boards used according to the invention.

The HDF board can be supplied pressed unfinished, that is, with the complete pressed skin. Preferably, however, the press skin is sanded to a thickness of about 0.3 mm to initially intentionally "weak form" the top layer.

First, 10 to 50 g/m2, preferably 30 g/m2 of aqueous melamine resin is applied as a tempering agent. It may be a standard impregnation resin with a solids content of 50 to 65% by weight, preferably 60% by weight. In addition to water as a solvent, other additives such as hardeners, wetting agents and the like may be present in the formulation. Alternatively, UF resin or, in mixtures, UF resin and melamine can be used as a tempering agent. This is a postforming resin or a standard impregnation resin that is made more elastic by adding flexibilizing agents (e.g. 1,4-butanediol, caprolactam, polyglycol, etc.). The subsequent addition of the elasticizing agent should be of the order of approximately 3 to 7% by weight. In order to be able to print the recesses 5, 6 on the upper side 2 of the construction board 1, it is then heated to a temperature of 30°C to 50°C by applying 10 to 30 g/m2 of water vapor.

After this pretreatment, one or more layers of resin-impregnated paper are applied to the top side 2 as an underlying layer 4.1 (cf. Figure 5) and then a decorative paper 3 is applied on top of it or alone (cf. Figure 3). The decorative paper 3 can be single-color or multi-color. Marks 7 can be placed on the decorative paper 3. Marks 7 can be circles 7.1, crosses 7.2, lines 7.3 and stripes 7.4 or other geometric figures. Using these marks 7, the construction board 2 can be aligned by a camera system to carry out further processing steps.

Next, a backing 8 is applied to the underside 9 of the construction board 1 and an overlay paper 4 is applied to 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 of which is provided with band-shaped elevations 32. The construction board 1 is aligned through the marks 7 and a camera system so that the elevations 32 emboss the recesses 5, 6 when the structure is pressed and thus form, parallel and flat, side walls 5.1, 5.2 and the lower wall 5.3. Between the band-shaped elevations 32, the pressing plate 31 can be provided with an engraving, through which a structure is embossed on the upper side of the overlying layer during pressing, which structure is at least partially aligned synchronous with the decoration (embossed in relief).

The pressing time in the short cycle press 30 is between 10 and 30 seconds, preferably between 12 and 15 seconds, during which the resins melt and bond to the build board 1. The temperature of the pressing plates 31 , 33 is up to 200°C. The pressure course goes from a pressure increase phase to a maintenance phase and a pressure release phase. The embossing depth T is thus determined in the sense of path control.

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

List of reference signs

1 Construction Board

2 Top side

3 Decoration

4 Abrasion Resistant Layer/Overlapping Paper

4.1 Underlay

5 Discount

5.1 Side wall

5.2 Side wall

5.3 Bottom wall

6 Discount

7 Marking

7.1 Circle

7.2 Cross

7.3 Line

7.4 Stroke

8 Support

9 Bottom side

30 Short cycle press

31 Press top plate

32 Band lift

33 Lower pressing plate

at angle

L Longitudinal direction

Q Transverse direction

T Depth

Claims (15)

1. Method for perfecting a construction board (1) provided from a wood-based material, in particular MDF or HDF, having a bottom side (9) and a top side (2) having a decoration which is sealed by applying an abrasion-resistant layer (4), where a relief is embossed at least on the upper side (2), with the following steps: a) a decorative paper (3) is applied to the upper side and a paper is applied superimposed on the decorative paper (3) as an abrasion-resistant layer (4), b) the lower side (9) is provided with a support (8), c) the structure thus prepared is introduced into a short cycle press (30) and pressed at pressure and temperature d) during pressing, the relief is embossed on the upper side (2) with a depth (T) of at least a band-shaped recess (5) with two opposite side walls (5.1, 5.2) and a lower wall (5.3) that joins them, characterized in that before applying the decorative paper (3): e) a tempering agent is applied to the upper side (2), and f) at least in the areas where the relief is to be engraved, the upper side (2) is treated with superheated steam to reach a surface temperature of 30 to 50 °C. 2. Method according to claim 1, characterized in that at least one other recess (6) extending at an angle (a) transversely to the (at least one) recess (5) is embossed. 3. Method according to claim 2, characterized in that longitudinally running recesses and/or a plurality of transversely running recesses (6) are embossed. 4. Method according to claims 1 or 2, characterized in that the construction board (1) is an HDF board, the upper side (2) of which is provided with a pressed skin. 5. Method according to claim 4, characterized in that the pressed skin has a thickness of 0.3 to 0.5 mm. 6. Method according to one of the preceding claims, characterized in that the apparent density of the construction board (1) in the upper layer that forms the upper side (2) is between 950 and 1,000 kg/m 3 . 7. Method according to one of the preceding claims, characterized in that the tempering agent is an aqueous melamine resin. 8. Method according to claim 1, characterized in that at least 10 g/m 2 of water vapor is applied. 9. 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. 10. Method according to one of the preceding claims, characterized in that the lower wall (5.3) of the at least one recess (5, 6) has a stepped shape. 11. Method according to one of the preceding claims, characterized in that the marks (7.1, 7.2, 7.3, 7.4) are engraved on the lower wall (5.3) of the at least one recess (5, 6). 12. Method according to one of the preceding claims, characterized in that at least one layer of resin-filled cellulose is applied as an underlying layer (4.1) before applying the decorative paper (3). 13. Method according to one of the preceding claims, characterized in that , in addition to the relief, a structure is embossed that runs, at least partially, synchronously with the decoration. 14. Method according to one of the preceding claims, characterized in that the embossing of the at least one recess (5) is carried out by means of a deeply structured pressing plate (31), preferably by means of band-shaped elevations (32) on the pressing plate. (31). 15. Method according to one of the preceding claims, characterized in that the construction board (1) is divided into individual panels by making a saw cut in and along each of the recesses (5, 6).