EP0702115B1 - Plasterboard with coated glass fiber mat - Google Patents

Abstract

To one flat side of the core (1) of the plaster structural plate connects a glass fleece layer (2), which outwardly is provided with a calcium sulphate coating (3). The glass fleece layer is divided into two coat-type areas (4,5), whereby the one area (4) is filled with a coating mass, which also forms the calcium sulphate coating. The other area (5) is filled with a core mass, which also forms the plate core. The coating masses are in contact with one another in the glass fleece layer along a dividing surface (6). The commencement of stiffening of the coating mess amounts to at least 1.5 hours and at most 6 hours. The plate has an average lift-off strength of at least 0.20 N/mm<2>. The calcium sulphate is a calcium sulphate anhydrite.

Description

The invention relates to a plasterboard with coated Glass fleece layer, with at least one side of a plate core is covered with the glass fleece layer, the plate core Apply a calcium sulfate coating on the opposite side is, in the core mass forms the plate core and on the one hand penetrated into the glass fleece layer and coating compound forms the calcium sulfate coating and on the other hand has penetrated into the glass fleece layer where the coating mass is formed on the basis of a calcium sulfate and contains organic binder and in which the core mass is formed from calcium sulfate dihydrate, the calcium sulfate coating including glass fleece layer on the plate core at any point across the plate level with a right angle lifting strength measured at the plate level is and the plasterboard in the shortly after the state of manufacture is present. The plasterboard is in an unprocessed condition and the A certain setting behavior can be assigned to coating compound.

A plasterboard of this type is essentially known (DE-OS 39 37 433). As is usual with plasterboard, this is Core mass formed on the basis of calcium sulfate dihydrate. The coating composition consists of an at least partially inorganic binder set with water, under other from plaster. About setting degree or setting speed nothing is said about the mixture. Additions to the setting the setting speed of the plaster are not intended. The plasterboard at issue here has the Advantage that a subsequent filling of the surface is eliminated and this surface is coated directly with emulsion paint, Wallpaper, tiles or mats can be covered. The production The plasterboard is made by first laying a glass fleece sheet unilaterally with a set mixture from a inorganic binders, e.g. Calcium sulfate hemihydrate and Water coated, after partial setting and drying the coating rolled up and then with the uncoated Side with a pasty mixture that can be set a mixture based on calcium sulfate hemihydrate and water is brought into contact so that it Mixture only partially penetrates into the glass fleece while doing so after the plaster has set one with a coated Glass fleece-laminated plasterboard is created.

In the known plasterboard of the type mentioned, the coating composition sets quickly. No information is given on the extent of the at least partially existing binding. It is also not specified that the core composition and the coating composition have contact with one another in the glass fleece layer. If a gypsum building board of the type mentioned at the outset is to be useful in practice, then the quality of the bond from the calcium sulfate coating to the board core is important. The quality of this composite can be described by the lifting strength, which indicates the force / area with which a measuring disc adhered to the coating is pulled until the composite is destroyed. According to experiments with the known plasterboard of the type mentioned, a lifting strength of 0.1 N / mm ^{2 is} not sufficient for the practical use of the plasterboard. Delaminations or internal splitting can occur in the glass fleece layer, which is a considerable disadvantage particularly when applying heavy coatings such as heavy paper or textile wallpapers or ceramic tiles. To remedy this disadvantage, there is no other option than to fill the surface with a suitable filler in a thin consistency so that it penetrates deeply into the fleece, thus strengthening the surface and improving the bond to the gypsum core. This means an additional cost-intensive operation on the construction site.

The coating causes glass fiber abrasion on the outer surface the plasterboard prevented. If the plasterboard is cut or drilled, but then occurs on the Processing points fiberglass abrasion in a considerable Scope on. Firstly, between the coating mass and the core mass a non-woven area in which the non-woven fibers are not enveloped by mass. In particular, however, is the coating compound relatively brittle and brittle, which can sometimes already on the wound rolls of the coated Fleece shows that when processing, i.e. when drilling and Saws, glass fibers from the fleece, initially from coating material are enveloped, released. At the processing points Glass fiber abrasion therefore occurs disadvantageously.

It is therefore an object of the invention to provide a plasterboard of the type mentioned at the outset, in which glass fiber abrasion can essentially not occur at processing points produced by sawing or drilling. The gypsum building board according to the invention solves this problem, characterized in that the calcium sulfate of the coating composition is not or almost not set and that the core composition is brought into contact with the coating composition almost continuously so that the lifting strength is at least 0.15 N / mm ² is.

Due to this design, fiberglass abrasion is at processing points almost completely avoided. The coating mass is tough and strong and does not release glass fibers. Because the core mass almost in contact with the coating compound brought, there are no more non-woven fibers that are not are enveloped by mass. The practically fiberglass-free The new plasterboard also makes the surface for the Suitable for ventilation ducts and cable ducts. The extent of penetration of the glass fleece layer with Core mass or the application of core mass to coating mass can by the improved lifting resistance specify at every point of the calcium sulfate coating. In addition, the plasterboard according to the invention has excellent Coating properties, so that even heavy Coating materials such as Wallpaper, tiles or Mats, a firm and permanent bond with the plate come in without first filling or any other elaborate treatment of the surface would be required.

Regardless of how deep the coating mass is in the Glass fleece layer has penetrated, it is ensured that the The core mass has penetrated so deeply into the glass fleece layer that the desired continuous contact of coating material and core mass is given. This is also an improvement in the lifting resistance by reduction the risk of splitting the glass fleece layer. It is a known (GB-OS 20 53 779) technology, a To produce plasterboard so that the core mass in the Glass fleece layer has penetrated more or less. At the gypsum board according to the invention is the core mass in the glass fleece layer penetrated so far that it in continuous Contact with the previously penetrated Coating has come.

The bond quality is particularly increased in that the Calcium sulfate of the coating composition as a nucleating agent for the Gypsum formation of the core mass is used. This creates the Connection point between core mass and coating directional growth of a plaster layer, which extremely improves adhesion works (epitaxy).

The slow setting speed is within the scope of the invention usually given when the coating material is on the start of stiffening according to DIN 1168 is at least 1.5 hours and a maximum of 6 hours. Especially It is expedient and advantageous if the stiffening begins the coating mass at least 2.5 hours and / or is a maximum of 5 hours. Proven in this setting time range the invention is particularly good in practice.

The calcium sulfate of the gypsum board not yet processed is not or almost not set; the Degree of rehydration of the coating mass is <5%, i.e. that a maximum of 5% of what was initially planned when switching on Calcium sulfate converted to calcium sulfate dihydrate to have. As a rule, however, the calcium sulfate is the coating material up to a maximum degree of rehydration 2% not tied.

In the plasterboard according to the invention touch each other the core mass and the coating mass in the glass fleece layer almost continuous. The interface between the core mass area and the coating mass area is partially formed from nonwoven fibers, so that in this Area of contact between the core mass and coating mass cannot take place. In addition, the Gypsum body of the core through the usual addition of air entraining agents and by evaporating the excess Mixing water is porous during drying. To that extent it doesn't help the degree of touch between Core mass and coating mass by proportions of one Separation area between core mass area and coating mass area specify. The extent of the touch is therefore described by its resistance to lifting.

In the case of the gypsum building board, the core mass is brought into contact with the coating mass in such a way that the internal strength of the system, expressed by the lifting strength, is at least 0.15 N / mm ² at every point. It is particularly expedient and advantageous if there is an average lifting strength of at least 0.20 N / mm ² . The plate according to the invention proves particularly well in practice at this limit value of the lifting resistance.

It is particularly expedient and advantageous if the coating composition Calcium sulfate is hemihydrate and additives contains a slow setting speed of the calcium sulfate hemihydrate cause. When using calcium sulfate hemihydrate is achieved by the additions that the coating mass of the gypsum building board not or almost is not set.

As a rule, the calcium sulfate hemihydrate is more effective Stucco. For the slow setting speed are on in any case, additives in the form of retarders. To suitable retarders include e.g. Citric acid and protein hydrolyzates.

It is particularly expedient and advantageous if the coating composition when switching on, regardless of what is added Water has the following composition: 60-95 % By weight stucco, 0.01-1% by weight cellulose ether, 0.03-0.5 % By weight retarder, 0.05-1.0% by weight of condenser. Especially It is advantageous if the coating composition up to 25% by weight limestone powder and up to 5% by weight PVAC dispersion contains. With such a coating compound the fleece fibers in the plate are particularly well held and the glass fiber abrasion resistance is particularly good. The Limestone flour is a filler. The condenser is e.g. Lignin sulfonate, a naphthalene sulfonic acid condensation product or a melamine resin.

It is also particularly expedient and advantageous if the Coating composition contains a plasticizer. The plasticizer is only in small quantities, e.g. maximum 5% by weight available and e.g. a polyacrylate or a styrene / butadiene. The plasticizer makes the coating compound plastic and flexible, which is their ability to make the fibers permanent and firm to envelop, improved.

Another particularly expedient and advantageous embodiment of the invention consists in that the calcium sulfate is a calcium sulfate anhydrite which is fine-grained with a grain size of <200 μm , preferably <63 μm and is partially capable of setting. In the present case, this special anhydrite can be provided as a plaster coating on the glass fleece layer. This anhydrite has an advantageous ability to penetrate the fleece surface and forms an optimal bond with the binder and fleece. The anhydrite preferably has a grain size average d ₅₀ between 8 and 12 μm .

During the production of the plasterboard, occurs at the molding station minimal calcium sulfate abrasion when laying on the coated glass fleece layer on the long production times collects. If the calcium sulfate of the coating composition Is anhydrite, then this calcium sulfate abrasion does not lead to Baking on the production lines. Particularly useful and it is advantageous in this context if the coating mass when starting, regardless of added water, has the following composition: At least 94% by weight calcium sulfate anhydrite, 0.01-0.8 % By weight cellulose ether, 0.01-1.0% by weight plasticizer and maximum 0.2% wetting agent.

The organic binder, which in the present case in the Coating mass is provided, e.g. Polyacrylate or Styrene acrylate. Organic binders deteriorate in the Rule the fire behavior and increase the toxicity of the resulting Smoke gases in the event of a fire. In the case of the invention Plasterboard, however, can contain the binder proportion relatively be kept low. Particularly useful and advantageous so it is when the organic binder is less than 6% by weight of the dry coating composition. The calcium sulfate that has not set or has not set, but is still reactive the coating composition thus enables a reduction the proportion of organic binder.

In a further embodiment, the coating composition up to 40% by weight aluminum hydroxide or boric acid admitted. This ensures that the Plasterboard meets the criteria for building material class A1 according to DIN 4102 fulfilled.

It is also particularly expedient and advantageous if at the plasterboard according to the invention with the ratios the calcium sulfate coating provided glass fleece layer are set so that the coating composition is superficial has a maximum abrasion of 0.2 g. This little abrasion is because of organic binder, fleece and calcium sulfate form an optimal adhesive bond.

The abrasion resistance is determined on the basis of this to DIN 53109, "Testing of paper and cardboard: determination of abrasion using the friction wheel method "and ISO 4586-2 "Abration resistance of decorative laminated sheets." As an abrasion device is used by the Teldyne Taber Standard Abrasion Tester. The standardized emery paper S-33 is placed on the friction wheels upset. Each friction wheel comes with an additional weight loaded by 500 g. The friction wheels are left during the test with the emery paper S-33 for 10 turns on the Act on the surface of the plate. After that the abrasion is through Determination of the weight difference determined.

Another advantage of the plasterboard according to the invention is that the resistance to lifting off after further surface treatment (primer, paint, wallpaper or plaster) is increased. Plates of a manufacture according to the invention have an average lifting strength of 0.34 N / mm ² after production, the minimum value from six measurements across the plate width being 0.23 N / mm ² . Part of the boards is painted with an aqueous dispersion primer, the other part is coated with a thin plaster based on gypsum. The average lifting strength reaches 0.42 N / mm ² after priming and 0.43 N / mm ² after thin-plaster application: the minimum values increase to 0.24 and 0.28 N / mm ² .

The coating composition based on calcium sulfate comprises when dressing as an inorganic binder either only hemihydrate or only anhydrite. The core mass is composed as is discussed for plasterboard here standing type is common and as with conventional plasterboard is used. The plasterboard according to the invention is used on conventional production lines for plasterboard manufactured. The plasterboard is behind their manufacture in the unprocessed state when stored and / or transported and / or mechanically fastened becomes. A processed state exists when the plasterboard is built into a building. If the coating mass with the built-in plasterboard with wallpaper, Tiles or foils is covered, it absorbs water and the calcium sulfate can partially rehydrate.

Fig.1 eine Draufsicht mit Aufbrüchen auf ein Teil einer Gipsbauplatte mit beschichteter Glasvlieslage,

Fig.2 eine Seitenansicht der Gipsbauplatte gemäß Fig.1,

Fig.3 eine Fotografie eines Schnittes der Gipsbauplatte gemäß Fig.1 und

Fig.4 eine Fotografie eines Schnittes einer weiteren Gipsbauplatte.

In the drawing, a preferred embodiment of the invention is shown and shows

1 is a plan view with cracks on part of a plasterboard with a coated layer of glass fleece,

2 shows a side view of the plasterboard according to FIG. 1,

3 shows a photograph of a section of the plasterboard according to Fig.1 and

4 shows a photograph of a section of another plasterboard.

The plasterboard according to Figures 1 and 2 has a board core 1, on the one side of which there is a glass fleece layer 2 connects to the outside with a calcium sulfate coating 3 is provided. The glass fleece layer 2 is in two layer-like regions 4, 5, one region 4 is filled with a coating compound, which is also the coating 3 forms, and the other area 5 with a core mass is filled, which also forms the plate core 1. The The core mass and the coating mass touch each other the glass fleece layer 2 along a separating surface 6.

The intimate contact between the core mass and the coating mass can be determined using scanning electron microscopy Show recordings. Fig. 3 shows the perfect one Contact of both layers that penetrated the glass fleece layer are. 4 is the underlying plate Stucco was added to iron oxide before mixing. With the help of Electron beam microsensor is used to determine how far the Core mass has penetrated the glass fleece. How to get out the spectra can see is the nuclear mass up to that point marked with "2" penetrated. The digit "1" shows no iron peak. Because such analyzes in practice too are elaborate, the degree of contact is affected by the Lift resistance described.

The calcium sulfate coating 3 is as thin as a film and a maximum of 200 μm thick. The structure of the fleece can be seen through the coating 3, since this is like a thin spread on the fleece.

Claims (18)

1. A plasterboard with a coated glass-fibre mat,

   in which at least one side of a board core is covered with the glass-fibre mat, of which the side remote from the core is provided with a calcium sulphate coating,

   in which core mass forms the board core and penetrates the glass-fibre mat on one side, and coating mass forms the calcium sulphate coating and penetrates the glass-fibre mat on the other side,

   in which the coating mass is formed on the basis of a calcium sulphate and contains organic binder,

   and in which the core mass is formed from calcium sulphate dihydrate,

   wherein the calcium sulphate coating with the glass-fibre mat adheres to the board core over the whole board plane with a peeling strength measured at right angles to the board plane, and wherein the plasterboard is in the state existing shortly after manufacture,

   characterised in that the calcium sulphate of the coating mass is unset or barely set,
   and in that the core mass is brought into continuous contact with the coating mass in a virtually planar manner in such a way that the peeling strength is at least 0.15 N/mm².
2. A plasterboard according to claim 1, characterised in that the coating mass takes at least 1.5 hours to begin to harden.
3. A plasterboard according to claim 1 or 2, characterised in that the coating mass takes at least 2.5 hours to begin to harden.
4. A plasterboard according to claim 1, 2 or 3, characterised in that the coating mass takes a maximum of 6 hours to begin to harden.
5. A plasterboard according to any one of the preceding claims, characterised in that the coating mass takes a maximum of 5 hours to begin to harden.
6. A plasterboard according to any one of the preceding claims, characterised in that the average peeling strength is at least 0.20 N/mm².
7. A plasterboard according to any one of the preceding claims, characterised in that the calcium sulphate of the coating mass is calcium sulphate hemihydrate which contains additives effecting a slow setting speed of the calcium sulphate hemihydrate.
8. A plasterboard according to claim 7, characterised in that the coating mass, independently of the added water, has the following composition when mixed: 60% - 95% by weight of plaster of Paris, 0.01% - 1% by weight of cellulose ether, 0.03% - 0.5% by weight of retarder, 0.05% - 1.0% by weight of liquefier.
9. A plasterboard according to claim 7 or 8, characterised in that the coating mass contains up to 25% by weight of limestone powder and up to 5% by weight of PVAC dispersion.
10. A plasterboard according to any one of claims 1 to 6, characterised in that the calcium sulphate is a fine-grained calcium sulphate anhydrite which has a particle size < 200 µm and is partially hardenable.
11. A plasterboard according to claim 10, characterised in that the particle size of the calcium sulphate anhydrite is < 63 µm.
12. A plasterboard according to claim 10 or 11, characterised in that the coating mass of calcium sulphate anhydrite has an average particle size d₅₀ of between 8 µm and 12 µm.
13. A plasterboard according to any one of claims 10 to 12, characterised in that the coating mass, independently of the added water, has the following composition when mixed: at least 94% by weight of calcium sulphate anhydrite, 0.01% - 0.8% by weight of cellulose ether, 0.01% - 1.0% by weight of liquefier and at most 0.2% by weight of wetting agent.
14. A plasterboard according to claim 1, characterised in that the calcium sulphate of the coating mass is unset up to a rehydration level of at most 2%.
15. A plasterboard according to any one of the preceding claims, characterised in that the coating mass contains a plasticiser.
16. A plasterboard according to any one of the preceding claims, characterised in that the abrasion of the coating mass, measured by the Teledyne Taber Standard Abrasion Tester according to ISO 4586-2 and DIN 53109, is at most 0.2 g.
17. A plasterboard according to any one of the preceding claims, characterised in that the organic binder makes up less than 6% by weight of the dry coating mass.
18. A plasterboard according to any one of the preceding claims, characterised in that the coating mass contains up to 40% by weight of aluminium hydroxide or boric acid.

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