WO1992013150A1 - Process for the manufacture of mineral-fibre plates capable of acting as plaster substrates, a device for carrying out the process, and mineral-fibre plate manufactured by the process - Google Patents

Abstract

Mineral-fibre plates manufactured by the process proposed have a low mean density and their manufacture therefore requires little fibrous material. Impregnation can be carried out with only small quantities of colloidal silicic acid and gives a good plaster-carrying substrate. The plates are manufactured by compressing a layer (11) of mineral fibres in length and thickness and then splitting the layer into two continuous strips (35, 37). One strip (35) is compressed and then fed back to the other web (37) and combined with it in a continuous-throughout oven (45) to give a single strip (49). The surface of the high-density layer (35'') in the final strip is subsequently sprayed with an impregnating compound from a nozzle (51). The strip then passes through an underpressure zone (53) in which the impregnating compound is sucked into the region (57) of the strip close below the surface.

Description

 Process for producing mineral fiber boards which can be used as plaster base, apparatus for carrying out the process and mineral fiber board produced by the process

The invention relates to a method for producing mineral fiber boards that can be used as a plaster base, in particular facade insulation boards, in which method the mineral fibers provided with a binder are accumulated to form a mineral fiber layer, the mineral fiber layer is split into at least two partial webs, at least one of the partial webs is compressed, the compressed partial web is fed to the or the other partial webs and the partial webs are combined by curing the binder to form a web which has at least one layer of high density and one layer of low density. Such a method is described in Canadian Patent 1,057,183. In the plates produced in this way, the fibers lie in parallel planes. They are therefore unsuitable or only poorly as facade panels, because there is a risk of delamination with this use. This danger is particularly great if suction forces act on the facade due to strong winds.

In a known method, mineral fibers are provided with a binder to form a mineral fiber layer, which is then compressed into a thin fleece, which is then folded so that a web is formed in which the thin fleece alternately perpendicular to the web from top to bottom and from runs from bottom to top. The disadvantage here is that the web formed in this way, or the plates produced therefrom, have a low strength in the longitudinal direction and have no flat surface.

The Swiss patent specification 620 861 describes a method in which mineral fibers wetted with a binder are deposited on a conveyor device running at a first conveying speed in order to form a mineral fiber layer in order to feed them to a continuous furnace, the conveying device of which is equipped with a second , reduced speed runs. The mineral fiber layer is at Entry into the continuous furnace is alternately bulged and then compressed in its thickness so that it has a practically flat surface after hardening. The plates produced in this way have a compressive strength and tensile strength at right angles to the plane of the plate, which is considerably higher than that of plates in which the fibers run in parallel planes. If a certain compressive strength is required, the plate described can be manufactured with a smaller density and thus cheaper than a plate with parallel fibers. The arrangement of the fibers in the plate described has a relatively high regularity. This makes it possible to use fewer binders in the production of the plates than in the previous processes.

The panels produced in this way are not suitable as facade insulation panels for the production of a plastered facade because plaster adheres insufficiently due to the hydrophobic nature of the panel material. In order to ensure sufficient adhesion of plaster, the insulation board according to DE-C-24 55 691 provides a coating of water glass with additions of fine-grained clay mineral substances. However, this requires thermal post-curing at relatively high temperatures. However, high temperatures have an unfavorable effect on the binder of the fibers and thus on the mechanical strength of the mineral fiber board.

In order to avoid the disadvantage of the insulation board according to DE-C-24 55 691, EP-B-0 114 965 proposes to provide facade or roof insulation boards made of synthetic resin-bound mineral fibers with a coating based on colloidal silica and particulate organic additives . This coating consists of an impregnation layer and a surface layer. The impregnation layer is created by pressing the coating composition into the resin-bonded mineral fiber board, breaking fibers in the area near the surface, and has a thickness of one or more millimeters. The top layer above the impregnation layer surface layer is formed from the coating material itself. It has the shape of a closed film and completely covers the broken surface fibers, so that they do not appear anywhere on the surface.

In the cited patent specification it is expressly stated that if silica sol is used exclusively, no layer or film formation that even approximates the requirements can be expected. The use of inorganic additives is therefore proposed and required that the inorganic additives are at least largely free of electrolytes and swellable layered silicates. The spatial weight of the insulation boards to be coated is relatively high, because otherwise coating is practically impossible. The preferred range is the range between 130 and 170 kg per cubic meter. The commercially available panels have a density of 150 kg per cubic meter.

Ground basalt fibers, kaolin and / or aluminum hydroxide are mentioned as inorganic additives in a quantity which is practically the same size or larger than the solids content of the colloidal silica. The addition of ground basalt fibers is considered necessary in order to fill the gaps between the broken mineral fibers of the insulation board with fiber structures and to enable a closed top layer.

The plate described has a number of disadvantages. Because of the necessary, relatively high density, a lot of fiber material is required to manufacture the plate. The plate

»Is therefore reasonably expensive. On top of that, too

«For the coating consisting of an impregnation layer and a top layer, a relatively large amount of coating material is required, which also makes the plate more expensive. Since colloidal silica tends to shrink when hardening, the need for a top layer can lead to warping of the plate. A covering layer with fillers also has the disadvantage that these markings on the plate be made invisible. It is therefore not possible to make a mark in the form of a grid with a distance of 10 cm between the lines before coating in order to facilitate cutting the panels to fit the building.

A particularly great disadvantage of the plates described is that their fibers run in parallel planes, so that the risk of delamination is great. Furthermore, since the top layer covers the broken mineral fibers, it is also not possible to bond these fibers to the plaster to be applied. There is therefore a risk that the plaster will peel off. Furthermore, breaking up the fibers in the area near the surface, as is required for the production of the coating, is also disadvantageous because the plate loses mechanical strength as a result.

It is therefore an object of the present invention to provide a method with which mineral fiber boards which can be used as plaster base can be produced inexpensively, which require relatively little fiber material for producing the insulating plate body and relatively little binder for producing the plaster base layer, do not tend to delaminate and have a high density with a correspondingly high insulating effect. The binder for producing the plaster base layer should not have to contain fillers which cover the markings made on the plate. In particular, there should also be no need to break fibers in the region of the mineral fiber plate near the surface during the production of the plaster base layer and thereby weaken the plate. The plate should also have the property of easily adapting to the unevenness of the wall when applied to the building.

The invention is based on the method according to CA-B-1 057 183, in which method the mineral fibers are provided with a binding agent to form a mineral fiber layer. the mineral fiber layer is split into at least two partial webs, at least one of the partial webs is compressed, the compressed partial web is fed to the or the other partial webs, and the partial webs are combined by curing the binding agent to form a web which has at least one layer of has high density and a layer of low density. The invention is characterized in that the mineral fiber layer is subjected to longitudinal and vertical compression before being split into partial webs and that after the partial webs have been combined into one web, the free surface of the layer of high density is impregnated with an impregnating agent suitable as a plaster base. Since in the plate produced in this way, many fibers lie inside the plate differently than horizontally, ie at an angle to the plate surface, the plate has a high tensile strength and compressive strength transverse to the plate plane. Therefore, it is not easily prone to delamination. The arrangement of the fibers described also has the advantage that the binder suitable as a plaster base easily penetrates into the plate surface. It is therefore not necessary to break mineral fibers when impregnating. This in turn also enables gentler processes than pressing in with a roller, as is required in the prior art. Since the surface area to be impregnated has a high fiber density, the gaps between the mineral fibers are small, so that there is no need to include such gaps fill in ground mineral fibers. There is no need for fillers. This in turn has the advantage that the impregnation remains transparent and thus markings previously made on the plate are not made invisible. The impregnation layer can be kept relatively thin, so that the impregnation agent requirement is small. The fiber requirement is also relatively small because the plate can have a relatively thin layer of high density and a relatively thick layer of low density, so that the average density can be kept small. Thanks to the relatively small density, the plate also has a high insulation effect. The lack of a top layer has the advantage that fibers protrude from the impregnation layer and ensure good adhesion of the plaster when the plaster is applied. The impregnating agent suitable as a plaster base is advantageously sprayed onto said free surface. This has the

The advantage is that the surface remains rougher than when rolling in.

The alignment of the fibers is not disturbed, so that many fibers also protrude from the impregnation layer formed. A rough surface results in better adhesion of the plaster.

Since no roller is required to apply the binder, there is also no risk of contamination of the roller and consequent downtimes and rejects. After the application of the impregnating agent suitable as a plaster base, the web is advantageously passed through a zone in which there is a vacuum under the web, which promotes the penetration of the impregnating agent into the region of the layer of high density close to the surface. When using negative pressure, it proves to be advantageous that the plate has a relatively thick layer of low density and the layer of high density can be kept relatively thin. A relatively low negative pressure is therefore sufficient to achieve the desired suction effect for penetration of the impregnating agent to the desired depth. Instead of or in addition to a vacuum under the web, an overpressure can be applied over the web to promote the penetration of the liquid impregnation agent. In all these cases, in contrast to rolling a coating under high pressure, the material to be processed is protected. Colloidal silica is advantageously used as the impregnating agent, which is suitable as a plaster base. This impregnating and binding agent offers no problems in terms of compatibility with the mineral fibers and is also water-resistant.

It is possible to mark the web before or after cutting it into sheets with a mark, e.g. to see a grid. A grid is very much appreciated by the user on the construction site as an aid for adaptation work.

For certain applications it is advantageous to fix the surface of the layer of high density with a large number of perforations to the plaster on the mineral fiber board. to provide. These perforations enable the plaster to be anchored particularly well on the mineral fiber board.

The invention also relates to a device for carrying out the method with a first conveying device for receiving mineral fibers wetted with binder in order to form a mineral fiber layer and for conveying the mineral fiber layer to a continuous furnace at a first speed, a separating device for splitting the mineral fiber layer into at least two partial webs , a compacting device for compacting a partial web, a guide for returning the compacted partial web to the or the other partial webs, a second compacting device for further compacting and combining the supplied partial webs, a continuous furnace and is characterized in that a pre-press for reducing the mineral fiber layer conveyed to the first conveying device is provided, that a second conveying device is provided, which the pre-pressed mineral fiber layer with a reduced z promotes high speed that there is a guide-free section between the pre-press and the second conveying device, which is dimensioned such that the mineral fibers are mutually bulged and that an application device for applying an impregnating agent to the compacted partial web or to the layer of high density the track formed by the union of the partial tracks is provided. This configuration can be implemented in existing board manufacturing plants without great effort.

A marking device can be arranged after the continuous furnace. This can be used, for example, to attach a grid as a cutting aid for the panels. It is also possible to provide a perforating device, for example a spiked roller, for perforating the web surface after the continuous furnace. As already mentioned, perforation enables the plaster to be anchored particularly well on the mineral fiber plate. A device for generating a vacuum under the web is expediently provided at and / or after the application device. The penetration depth of the impregnating agent can be regulated according to the requirements by generating a suitable negative pressure. However, it is also possible to provide a device for generating an overpressure above the web at or after the application device in order to control the penetration of the impregnating agent.

The invention also relates to a mineral fiber plate which is produced by the method described.

For a better understanding of the invention, an embodiment of the invention will now be described in more detail with reference to the drawing. It shows:

1 shows a schematic representation of a device for carrying out the method according to the invention,

2 shows a schematic illustration of a mineral fiber plate which was produced using the method according to the invention.

In the exemplary embodiment of a device for carrying out the method according to the invention shown in FIG. 1, a layer of mineral fibers 11 is moved at a speed VI from a first conveying device 13 to a second conveying device 17. The second conveyor 17 consists, for example, of a lower and an upper conveyor belt 29 and 31, respectively, and moves at a reduced conveyor speed V2. A pre-press 19 is arranged between the two conveying devices 13 and 17 and essentially consists of two roller arrangements 21 and 23 arranged symmetrically to the conveying direction and converging to one another. The pre-press 19 compresses the thickness of the mineral fiber layer being conveyed. The roller conveyors 21 and 23 run at a speed which practically corresponds to the first conveying speed VI. After the last role of roller tracks 21 and 23 there is a section 25 without a guide there is a mutual bulging of the mineral fiber layer 11 because the speed VI is greater than the speed V2. The conveyor belts 29, 31 of the second conveyor 17 press the bulge 33 of the fibers regularly due to the prevailing force relationships up and down. Immediately after bulging, the mineral fiber layer 11 is compressed in thickness by the bands 29, 31. In summary, it can be stated that longitudinal and vertical compression takes place. Many fibers are brought into a position that is at an angle to the direction of movement of the mineral fiber layer.

After the longitudinal and vertical compaction, the mineral fiber layer is separated by a separating device 23, e.g. a band saw, split into two sections 35, 37. The partial web 35 reaches the pair of rollers 41 via the guide 39. The pair of rollers 41 compresses the partial web 35 relatively strongly. The compressed partial web 35 'is then returned to the lower partial web 37 via the guide 43. When entering the continuous furnace 45, the compressed partial web 35 'thus lies on the partial web 37. Between the conveyor belts 47 and 48, the two partial webs 35', 37 are pressed together a little and firmly joined together by curing the binder adhering to the fibers . This association contributes to the fact that the fibers arranged at an angle to the mineral fiber web interlock and are hooked together like a Velcro fastener.

After leaving the continuous furnace 45, there is a web 49 formed by the combination of the partial webs 35 ', 37, which has a layer 35 "of high density at the top and a layer 37' of low density at the bottom. The marking device 52 can be used If necessary, a marking can be applied, for example in the form of a grid (FIG. 2) in which the lines 54 are arranged at a distance of 10 cm in order to serve as a cutting aid when using the mineral fiber plate Marking can be done in a known manner in various ways, for example by local -IQ-

Heating by flame, hot air or infrared radiation. This causes local discoloration of the organic binder. It would also be possible to spray or print on a color. If desired, perforations 58 (FIG. 2) can be produced in the surface of the layer 35 ″ with a perforation device 50, for example a spiked roller, which serve to render the plaster particularly well when the plate is later used as a plaster base to anchor. The free surface of the layer 35 ″ of high density is then sprayed through the nozzles 51 with an impregnating agent suitable as a plaster base. A suitable impregnating agent is, for example, colloidal silica. The device 53 makes it possible to apply a vacuum under the web 49. This negative pressure favors the penetration of the impregnating agent into the region of the layer 35 ″ near the surface of high density. Instead of or in addition to the device 53, a device 55 can be provided with which an overpressure is generated over the web 49, which promotes the penetration of the impregnating agent into the region of the layer 35 ″ near the surface. To generate the overpressure, hot air is preferably used, which can be generated with waste heat in the production of mineral fibers. The hot air favors the hardening of the impregnating agent used as a plaster base. Instead of after the continuous furnace 45, the application device 51 could also be arranged in front of the continuous furnace 45, as shown in dashed lines. The same also applies to the devices 53 and / or 55. However, these can be dispensed with in particular if the continuous furnace 45 functions in a similar manner to these. For example, the continuous furnace can be operated with hot air so that there is overpressure in the upper part.

After the impregnating agent has hardened, the web is cut into plates 60 in the cutting station 59.

2 schematically shows the mineral fiber plate 60 produced with the method according to the invention. Reference symbol 57 denotes the impregnation layer serving as a plaster base referred to, which has a thickness of about 0.5 to 2 mm, preferably 1 mm. Perforations 58 which may be provided serve to anchor a plaster layer. The mineral fiber plate produced in this way has an average density of only about 105 kg per cubic meter with a thickness of 80 to 100 mm, which allows fiber material to be saved by about a third compared to known plates. The layer 35 ″ of high density has a density of approximately 150 kg per cubic meter. Since the low-density layer 37 'has a certain elasticity, the mineral fiber plate can also adapt to certain unevenness when it is installed on the building.

Various changes are possible without deviating from the inventive concept. This makes it possible to carry out the marking in different steps. A marking step and the impregnation can thus take place after the web 49 has been cut into individual plates 60.

Claims

Claims 1. A process for the production of mineral fiber boards which can be used as plaster base, in particular facade insulation boards, in which process the mineral fibers are provided with a binder to form a mineral fiber layer (11), the mineral fiber layer (11) is split into at least two partial webs (35, 37) If at least one of the partial webs (35) is compressed, the compressed partial web (35) is fed to the or the other partial webs (37), and the partial webs (35 ', 37) by curing the binder to form a web (49) are combined, which has at least one layer (35 * ') of high density and one layer of low density (37'), characterized in that the mineral fiber layer (11) before splitting into partial webs (35,37) of a longitudinal and Height compression is subjected and that after the partial webs (35 ', 37) have been combined to form a web (49) the free surface of the layer (35' ') of high density with an impr suitable as a plaster base gniermittel is impregnated. 2. The method according to claim 1, characterized in that the impregnating agent suitable as a plaster base is sprayed onto said free surface. 3. The method according to claim 1 or 2, characterized in that after the application of the impregnating agent suitable as a plaster base, the web (49) is passed through a zone (53) in which there is a vacuum under the web (49), which penetrates of the impregnating agent in the near-surface area of the layer (35 '') favored by high density. 4. The method according to any one of claims 1 to 3, characterized in that after the application of the impregnating agent suitable as a plaster base, the web is passed through a zone (55) in which over the web (49) Overpressure prevails, which favors the penetration of the impregnating agent into the region of the layer (35 '') near the surface of high density. 5. The method according to any one of claims 1 to 4, characterized in that colloidal silica is used as a suitable impregnating agent. 6. The method according to any one of claims 1 to 5, characterized ge indicates that the web (49) before or after cutting into plates with a mark, e.g. a grid is provided. 7. The method according to any one of claims 1 to 6, characterized in that the surface of the layer (35 '') of high density is provided with a plurality of perforations (58). 8. Device for performing the method according to one of claims 1 to 7, with a first conveying device (13) for receiving mineral fibers wetted with binder for the purpose of forming a mineral fiber layer (11) and for conveying the mineral fiber layer to a at a first speed ( VI), a separating device (23) for splitting the mineral fiber layer into at least two partial webs (35, 37), a first compacting device (41) for compacting a partial web (35), a guide (43) for returning the compacted partial web (35 ') to the or the other partial webs (37), a second compacting device (47, 48) for further compacting and combining the combined partial webs (35', 37), a continuous furnace (45), characterized in that a pre-press ( 19) to reduce the mineral fiber layer (11) conveyed by the first conveying device, it is provided that a second conveying device (17) is provided which Pressed mineral fiber layer with a second reduced in relation to the first speed (VI) Speed (V2) promotes that there is a guide-free section (25) between the pre-press (19) and the second conveying device (17) which is dimensioned such that the mineral fibers bulge out alternately and that after the continuous furnace (45) an application device (51) is provided for applying an impregnating agent to the compacted partial web (35 ') or to the layer (35'') of high density of the web (49) formed by combining the partial webs (35', 37) . 9. The device according to claim 8, characterized in that a marking device (52) is arranged after the continuous furnace. 10. The device according to claim 8 or 9, characterized gekennzeich¬ net that after the continuous furnace (45) or the Markier¬ device (52) a perforating device (50), e.g. a spiked roller is provided for perforating the web surface. 11. The device according to one of claims 8 to 10, characterized in that the application device (51) is arranged after the continuous furnace (45). 12. Device according to one of claims 8 to 10, characterized in that the application device (51) is arranged in front of the continuous furnace (45). 13. Device according to one of claims 8 to 12, characterized in that a device (53) for generating a vacuum under the web (49) is provided at and / or after the order device (51). 14. Device according to one of claims 8 to 13, characterized in that a device (55) for generating an overpressure above the web is provided at or after the order device (51). 15. Mineral fiber board produced by the method according to one of claims 1 to 7. 16. Mineral fiber board consisting of at least one layer (35 '') of high density, at least one layer of low density (37 '), which has an impregnation (57) in the area of the surface with an impregnating agent suitable as a plaster base. 17. Mineral fiber plate according to claim 15 or 16, characterized in that the layer (35 '') of high density has a plurality of perforations (58).