EP1858681B1 - Method for producing coated gypsum plasterboard - Google Patents

Description

The present invention relates to a process for producing coated plasterboard.

State of the art

Construction boards based on gypsum, hereinafter referred to as gypsum boards, are used in dry construction for the production of floors, walls and ceilings. The corresponding plates are manufactured industrially.

In gypsum plasterboard, stucco is typically mixed with water and various additives into a slurry and then poured onto a board web. Then a second board web is placed so that the plaster is enclosed before the setting of the two board webs. The strand is then passed over a binding band. During the time required for this, the stucco in the plate core binds to calcium sulfate dihydrate. The hardened strand is separated into plates by a suitable cutting device. This is followed by a drying process in which the excess water is removed. Instead of cardboard, it is also possible to use alternative products for cladding, such as glass fiber webs or textile nonwovens.

An alternative to this is gypsum fiberboards, which are typically made from gypsum and cellulosic fibers. For this purpose stucco and cellulose fibers are intimately mixed. Water is added to this mixture, which is sufficient for setting the stucco plaster. This so-called green plate is then pressed under pressure. After setting on the Abbindeststrecke and singling the plates are dried. Corresponding gypsum fiber boards are characterized in particular by their high mechanical strength.

After installation of the plates, the joints between the plates are usually filled, the resulting walls or ceilings primed and painted or papered. Painting or wallpapering is used as a decoration designated. Often before primers or wallpaper changes are applied.

Especially with perforated or slotted plates, the edges of the plates are usually pre-primed manually.

These related jobs are time consuming and expensive because they have to be done manually at the job site.

Various attempts have been made to include pretreatment and / or decoration in industrial manufacturing. (Prefabrication)

That's how it describes EP 0 777 800 B1 the use of a box with a top layer already prepared so that it can be decorated without pretreatment.

EP 1 076 137 A2 relates to a lining paper, which receives a decorative surface design by printing and is then used to produce a plasterboard.

It has been found to be disadvantageous to use such special paperboard materials, since they cause higher costs and in some cases hinder the drying process of the gypsum core. In the manufacture of plasterboard, it is essential that the board layers used have a high water vapor permeability to allow uniform drying of the gypsum core, while ensuring sufficient adhesion of the cardboard to the gypsum core.

The above-mentioned methods of the prior art are not applicable to gypsum fiberboards, since there are no outer board or nonwoven layers.

US 2003/0113572 describes a specific coating composition for a gypsum board containing a binder, soy protein and two or more Pigments. Although it is generally described in this document that the coating can take place before or after the stayer dryer and thus discloses the features of the preamble of claim 1, it is preferred that the coating composition is applied before the stayer dryer. Investigations of the mass described there have shown that it has drying times of well over 10 minutes and only dries well when used in front of the floor dryer.

WO 99/10151 relates to a material for the production of inorganic phosphate-based materials. It is described there on page 7 that a corresponding method for plasterboard is not applicable.

Description of the invention

The present invention has the object to develop a method by which the disadvantages of the prior art can be overcome.

Surprisingly, it has been found that it is possible to coat gypsum boards immediately after drying, without disturbing the usual process flow.

A coating in the sense of this application comprises both the application of primers and of means for decoration, such as colors.

Gypsum boards are dried in a continuous production process and, after passing through the drying station, trimmed, stacked and packed and / or provided with a strapping as transport security. Unstacking already stacked plates to further process them is generally a cumbersome process that would reduce the production capacity of such equipment.

1. a) Formen einer Gipsplatte;
2. b) Trocknen der Gipsplatte in einer Trocknungsvorrichtung;
3. c) Beschichten der Gipsplatte durch Besprühen mit einem Beschichtungsmittel im Anschluss an das Trocknen;
4. d) Stapeln der Gipsplatten,

wobei zwischen dem Ende des Beschichtens und dem Stapeln der Gipsplatten ein Zeitraum von weniger als 60 sec liegt, wobei das Trocknen des Beschichtungsmittels mit Hilfe der Restwärme der Platte erfolgt.The invention therefore provides a process for the production of a coated gypsum board, comprising in one operation the following steps in the following order:

1. a) forms a plasterboard;
2. b) drying the gypsum board in a drying apparatus;
3. c) coating the gypsum board by spraying with a coating agent following drying;
4. d) stacking the gypsum boards,

wherein a period of less than 60 seconds is between the end of the coating and the stacking of the gypsum boards, wherein the drying of the coating agent takes place with the aid of the residual heat of the plate.

According to the invention, therefore, the step of coating the gypsum boards is included in the manufacturing process and immediately follows the drying process. The still warm plate is sprayed with a coating agent. The residual heat of the plate surprisingly accelerates the drying of the coating agent so much that the coating agent is dried sufficiently until the step of stacking the gypsum boards to prevent sticking of the stacked plates together.

The step of forming the gypsum board includes the steps necessary to make the gypsum board until it enters the dryer. Herein may be included steps relating to setting or singulation.

According to the invention takes place between the drying of the gypsum board and the coating no stacking or transfer to another workstation, but the drying is followed directly by the coating. Subsequently, the gypsum board is stacked with other plates to form a plasterboard stack.

The inventive method is suitable for both plasterboard and gypsum fiber boards.

For spraying, depending on the width of the plate one or more spray nozzles are used, the spray areas can overlap. Typically, in the gypsum board production several plates are made in parallel and run together from the drying device at the same time. These are then coated simultaneously by a correspondingly larger number of spray nozzles. Particularly suitable spray nozzles are wide jet spray nozzles. In this case, for example, airless spray systems (Drucksprühsysteme) can be used or systems in which the spraying is carried out by a gas, such as air, so-called two-fluid nozzles or airless Duo nozzles (combination of airless and air jet atomization).

Systems of this type are commercially available. They work at pressures between 1 to 100 bar, sometimes up to 150 bar.

In one embodiment of the invention, the nozzles do not spray on the plate surface at 90 °, but slightly obliquely on the plate surface, the nozzles being arranged to spray with or against the transport direction of the plates.

In a preferred embodiment, the angle between the spray direction of the nozzles and the disk surface is 20 to 80 °, more preferably 30 to 60 °.

It is easily ascertainable to the person skilled in the art how the optimum angle or the optimal distance between spraying device and plate lies. Typical distances are in the range of 10 to 60 cm, more preferably in the range of 20 to 40 cm.

The coating composition preferably has a water content in order to avoid emissions due to evaporating solvents, etc. Preferred water contents are at least 30% by weight, more preferably at least 40% by weight and even more preferred water contents are at least 80% by weight or at least 95% by weight, in particular in primers.

Preferably, an application of coating material in an amount of 20 to 100 g / m ² (based on the dry weight of the coating agent).

According to the invention, there is only a short period of time between the end of the drying step and the stacking of the gypsum boards, which includes the coating step according to the invention. Typically, a period of less than 60 seconds, more preferably less than 40 seconds, and most preferably less than 30 seconds, is between the end of the coating and the stacking of the gypsum board. The shorter the times between coating and stacking, the smaller can be the plant will be built in the area after drying. The said time is the time after which the coated side of the produced coated gypsum board makes contact with another surface, typically by depositing another gypsum board on it during stacking.

The applicable coating compositions are diverse. It can be used e.g. water-repellent coating agents, water-barrier coating agents, wallpaper replacement primer, paints, impregnating agents, anti-slipping agents, liquid films and / or strength-increasing agents.

Simultaneous or sequential spraying with two or more coating agents is also possible.

Typically, gypsum board has a Cobb value of about 100 to 200 g / m ² for a two-hour exposure according to ASTM C473-87a. Further preferred values are in the range of 130 to 160 g / m ² . Since the gypsum core is already dried at the time of coating, it is irrelevant whether the coating used hampers the water leaving the surface. It is therefore also possible to use monomers for the coating, which subsequently polymerize. Even agents that solidify the surface, such as one-component resins, can be used.

In one embodiment, after coating, a further drying step is provided to accelerate the drying. In this case, for example, a drying by infrared radiation, hot air or the like can be used.

In another embodiment, such a further drying step is not provided.

Since the surface is directly coated in the case of gypsum plasterboard, paperboard materials which are of lower quality and have a less uniform appearance can in principle also be used. The coating still gives the plate a high-quality appearance. In principle, it is also conceivable to use different board qualities for the boards, so that only the side which is coated is produced from a board of inferior quality.

The plates thus obtained can - as in the usual way - be further processed, for example by punching, bending, slitting or trimming.

This subsequent processing step may also be integrated into the manufacturing process and performed prior to stacking the gypsum boards. However, it is also possible to spend the plates after stacking to another station and to do there further steps. Of course, it is also possible to integrate part of the post-processing into the production process and to carry out further post-processing later. Typical post-processing steps serve for the production of chamfer edges, step seam edges, etc.

In one embodiment, after drying, but before stacking, the gypsum boards are coated on at least one edge. This is particularly useful if the edges have been treated, for example by chamfering, training as Stufenfalzkante or V-milling. For this purpose, coating composition is applied to this edge region. As a result, the joint strength is increased. Corresponding processing can be connected directly to the processing of the edge by means of bundler or milling devices.

In another embodiment, it is also possible that after stacking, a treatment step may follow, in which edges of the stacked Plaster boards are coated by spraying with a coating material, in particular by a primer. Also, this can increase the edge strength.

The gypsum boards are advantageously used together with a putty compound to joint the joints formed between the boards, which has an identical color as the coating, so that even after grouting the boards a uniform appearance of the walls is achieved.

In a preferred embodiment, the coating is synchronized with the transport of the plates, i. The spraying is interrupted as soon as one plate leaves the spraying area and resets when the next plate reaches the spraying device.

• Die Vorrichtung weist eine Trockeneinrichtung zum Trocknen einer, insbesondere mehrerer Gipsplatten auf. Als Trockeneinrichtung kann beispielsweise ein Mehretagentrockner vorgesehen sein. Der Trockeneinrichtung vorgeschaltet kann eine zur Herstellung der Gipsplatte dienende Gipsplatten-Formungseinrichtung vorgesehen sein. Der Trockeneinrichtung nachgeordnet ist eine Förderreinrichtung, durch die die Gipsplatten nach dem Trocknen zu einer Stapeleinrichtung gefördert werden. Mit Hilfe der Stapeleinrichtung werden die Gipsplatten beispielsweise auf Paletten oder dgl. gestapelt. Erfindungsgemäß ist zum Beschichten der Gipsplatten unmittelbar nach der Trockeneinrichtung eine Beschichtungseinrichtung vorgesehen, durch die die noch warmen Gipsplatten beschichtet werden, wobei die Beschichtung, insbesondere wie vorstehend an Hand des erfindungsgemäßen Verfahrens beschrieben, durchgeführt wird. Die Beschichtung erfolgt somit vorzugsweise während des Transportes der Gipsplatte von der Trockeneinrichtung zur Stapeleinrichtung.

Particularly suitable devices for carrying out the method are described below:

• The device has a drying device for drying one, in particular several gypsum boards. As a drying device, for example, a multi-floor dryer can be provided. Upstream of the drying device can be provided for serving the plasterboard gypsum board forming device. Subordinated to the drying device is a conveying device, through which the gypsum boards are conveyed after drying to a stacking device. With the help of the stacking device, the gypsum boards are stacked on pallets or the like, for example. According to the invention, a coating device is provided for coating the gypsum boards immediately after the drying device, by means of which the still warm gypsum boards are coated, the coating being carried out in particular as described above with reference to the method according to the invention. The coating is thus preferably carried out during the transport of the gypsum board from the drying device to the stacking device.

In order to avoid fouling of conveying elements of the conveying device, such as a conveyor belt, during coating, which preferably takes place by spraying, a deflection device is preferably provided. By deflecting the conveying element is arranged or deflected in the coating area at a distance from the gypsum board. This has the advantage that the risk of contamination of the conveying elements or of the conveyor belt is considerably reduced. It is also possible to provide a receiving or collecting device in the region between the gypsum board and the deflected conveying element. If appropriate, coating material sprayed next to the gypsum board, for example, can thus be picked up by the receiving device, which may be a trough, and does not reach the conveyor belt.

The device is preferably further developed as described above with reference to the method according to the invention.

The invention will be explained in more detail with reference to a preferred embodiment with reference to the accompanying drawings.

Figur 1

eine schematische Seitenansicht einer ersten bevorzugten Ausführungsform der Vorrichtung,

Figur 2

eine schematische Seitenansicht einer zweiten bevorzugten Ausführungsform der Vorrichtung und

Figur 3

eine schematische, vergrößerte Ansicht des Beschichtungsbereichs.

Show it:

FIG. 1

a schematic side view of a first preferred embodiment of the device,

FIG. 2

a schematic side view of a second preferred embodiment of the device and

FIG. 3

a schematic, enlarged view of the coating area.

In a drying device 10, which is a multi-tray dryer in the illustrated embodiment, a plurality of gypsum boards 12 are arranged. By means of a conveyor 14, which is adjustable in height, for example via a hydraulic 16 in the direction of an arrow 18, the gypsum boards 12 are removed from the drying device 10 and transported via a second conveyor 20 to a stacking device, not shown, are stacked by the plasterboard 12, for example, on pallets.

In a first preferred embodiment of the device ( FIG. 1 ), a coating device 22 is provided in the region of the pivotable conveyor 14. The coating device 22 has spray nozzles 26 arranged transversely to a transport direction 24. With the aid of the spray nozzles 26, the gypsum boards 12 are coated while being transported by the conveyor 14 in the conveying direction 24.

In this case, a plurality of drying devices can be arranged next to one another, so that a plurality of gypsum boards can be transported side by side at the same time by the conveying device 14 and coated simultaneously by correspondingly provided spray nozzles.

The coating device 22 is in the first preferred embodiment ( FIG. 1 ) pivotable together with the conveying device 14, so that the distance between the spray nozzles 26 and the gypsum plates 12, regardless of the position of the conveyor 14 remains constant.

In a second preferred embodiment ( FIG. 2 ), the coating device 22 is not provided in the region of the pivotable conveyor 14, but in the region of the adjoining conveyor 20. This has the advantage that a pivoting of the coating device together with the conveyor 14 is not required.

In the area of the coating device 22, a deflection device 28 (FIG. FIG. 3 ) be provided. In the exemplary embodiment shown, the deflection direction has four deflection rollers 30, so that a conveying element 32, such as a conveying path, has a distance to the plasterboard 12 in a coating region 34. For collecting excess coating material is preferably between the gypsum board 12 and the conveying element 32nd in the coating area 34, a receiving device 36, such as a tub provided.

The invention is explained in more detail by the following examples.

example 1

A gypsum board was conventionally made on a line where a gypsum slurry is continuously applied to a board web and covered with a second board web. After the setting of the gypsum core, the plates are separated and transferred to a floor dryer. After drying, a coating was carried out with a device according to FIG. 2 , in which two wide-jet nozzles were used. The coating agent used was a water-based paint containing inorganic pigments, binders, emulsifiers and other stabilizers and stabilizers. The order was 65 g / m ² . Due to the residual heat of the plates, the coating composition dried within 20 seconds so far that the coated plates could be stacked directly on one another with a conventional device.

Example 2

The procedure was as in Example 1, but after removal from the dryer and the coating two adjacent edges of the gypsum boards were chamfered and then stacked the plates. The gypsum board stack was subjected to a further coating step at a further station where the edges were coated.

Claims (12)

1. A process for preparing a coated plasterboard, comprising the following steps in the following order in one production cycle:

   a) forming a plasterboard;

   b) drying the plasterboard in a drying device;

   c) coating the plasterboard by spraying with a coating agent after said drying;

   d) stacking the plasterboards;

   characterized in that there is a period of time of less than 60 seconds between the end of the coating and the stacking of the plasterboards, wherein the drying of the coating agent is effected by means of the residual heat of the board.
2. The process according to claim 1, characterized in that said plasterboard is a gypsum plasterboard or a gypsum fiber board.
3. The process according to either of claims 1 or 2, characterized in that said spraying is effected by one or more spraying nozzles, preferably wide jet spraying nozzles.
4. The process according to any of claims 1 to 3, characterized in that the angle between the direction of spraying and the board surface is from 20° to 80°.
5. The process according to any of claims 1 to 4, characterized in that said coating agent has a water content of at least 30% by weight.
6. The process according to any of claims 1 to 5, characterized in that there is a period of less than 40 seconds between the end of the coating and the stacking of the plasterboards.
7. The process according to any of claims 1 to 6, characterized in that said plasterboard is subsequently further processed, for example, by perforating, bending, slitting or bordering.
8. The process according to at least one of claims 1 to 7, characterized in that said coating agent is selected from water-repellent coating agents, water-barrier coating agents, wallpaper changing primers, color paints, impregnating agents, anti-skidding agents, liquid films, strength-increasing agents, bactericides and fungicides.
9. The process according to any of claims 1 to 8, characterized in that only a partial area of the plasterboard is coated in step c).
10. The process according to claim 9, characterized in that said partial area comprises one or more edges of said plasterboard.
11. The process according to any of claims 1 to 10, characterized in that said plasterboard is additionally coated on at least one edge by spraying with a coating agent.
12. The process according to any of claims 1 to 11, characterized in that at least one edge of the stacked plasterboards is coated by spraying with a coating agent after stacking.

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