CA2241069A1

CA2241069A1 - Web-shaped semifinished product, in particular wall covering plaster, and process for producing the same

Info

Publication number: CA2241069A1
Application number: CA002241069A
Authority: CA
Inventors: Helmut Wedi
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-10-23
Filing date: 1997-10-23
Publication date: 1998-04-30
Also published as: EP0871810A1; PL183740B1; ES2188918T3; EP0871810B1; PL327631A1; WO1998017855A1; ATE230043T1; HUP9901982A3; HU224487B1; HUP9901982A2

Abstract

In order to obtain a semifinished product, in particular a wall covering plaster, which behaves as applied plaster and is easy to produce, process and shape, an artificial resin mortar (11) is applied on a flat side (21) of a nonwoven strip (2) with a thickness from 0.05 mm to 3 mm and an air permeability from 500 l/m2.s to 4,500 l/m2.s. The artificial resin mortar (11) has the following composition in the non-hardened state: 50 to 90 wt % of a powdery component composed of finely granulated cement and finely granulated aggregates and 10 to 50 wt % of a liquid component with elastic properties, as well as a spreading value from 100-350 mm. Depending on an advance speed from 1 to 15 m/min, the mortar (11) penetrates at least partially into the pores (22) of the nonwoven strip (2) which ensure its air-permeability and forms in the hardened state at least one flexible mortar layer (1) and an impregnation layer (3) in the pores (22).

Description

WEB-SHAPED SEMIFINISHED PRODUCT, IN PARTICULARWALL
COVERING PLASTER, AND PROCESS FOR PRODUCING THE SAME
The present invention concerns a semifiniched web, specifically a plaster-impregnated wall covering, and a method of manufacturing it. At least one side of a flat 5 and at least to some extent flexible base is coated with a coating that will be flexible subsequent to hardening.

A semifini ched web of this type is known from German Patent No. 3,111,899 A, which describes coating a glass-fiber non-woven fabric weighing 50 g/m2 with a sealant weighing 150 g/m2 that penetrates at least part-way into the fabric.

The sealant comprises:
18 to 20 % di-isodecyl phth~l~te;
0.5 to 1 % zinc stabilizer;
8 to 10 % ethyl glycol;
30 to 35 % powdered polyvinyl chloride; and 20 to 25 % talc.
Plastic weighing 200 g/m2 is then applied to the sealant and expanded at conventional temperatures. The layer of expanded plastic can be provided with a decorative pattern.

Mineral substances like talc, calcium carbonate, and titanium oxide and tempering 20 materials like ultraviolet absorbers and PV stabilizers are intended to ensure a certain level of weathering resistance. The elasticity of the sealant and plastic are admittedly ensured by softeners, which displace the thermoplastic range to lower temperatures. To ensure the resistance of the plastic, however, requires minimi7~tion of the wall-resistant softeners and of their proportions. Coating the fabric, however, is costly and consumes considerable 25 material. This semifini.ched web is also too thick and too heavy.

A wall covering with a base of expanded plastic covered with paper or plastic with a layer of barite filler between them is known from German Patent No. B 1,150,941.

One drawback to this wall covering is that it results in a wall of two sheets, which, although it does provided insulation against noise, is too thick and too heavy. The thickness decreases flexibility and makes it difficult to unroll and handle.

A wall-covering sheet or board is known from German Patent No. U 7,931,745 Ul. It is made of extruded polystyrene foam. The sheet is 1 to 3 mm thick and up to 1200 mm wide and the board 2.5 to 6 mm thick and either 800 x 1250 or 800 x 1200 in size. A
layer contail~ g an adhesion promoter is applied to one side. The a&esion promoter comprises diluted dispersion a&esives that attach the sheet or board to the wall. When between 50 and 100 g/m3 are applied, flame retardants must also be included to decrease fl~mm~bility.

European Patent No. A 78,404 discloses an insulated outer-wall covering board.
It comprises insulating board with a layer of plaster. The plaster is composed of granulated or powdered insulation, woven glass fiber covered with a sheet of plastic, and a cement binder of plastic dispersed in water.

l S The drawback to this wall covering is a high strength that makes it very rigid.

A l~min~ted board and a method of m~mlfacturing it is known, finally, from German Patent No. C 4,239,269. It comprises an expanded-plastic core with at least one side coated with a curing-plastic mortar, embedded with woven glass fiber. The board is manufactured by applying the mortar to the expanded plastic and forcing the continuous 20 web of glass fiber into it. Excess mortar is then scraped off with a doctor and allowed to accumulate. How much mortar is employed is regulated by detecting the accumulation.
The still moist mortar and its reinforcement, and the core as well if necessary, are then trimmed, to size and the mortar allowed to dry and cure.

This laminated board and its method of manufacture have been proven practical.
25 Since, however, the expanded-plastic core is at least 30 mm thick and the mortar both rigid and more than 0.5 mm thick, the board, even at its thinnest is not pliant enough to be handled as conveniently as even a thin slab of stone.

One object of the present invention is accordingly an improved semifini.ched weband specifically a plaster-impregnated wall covering of the aforesaid type that will act externally like a layer of plaster and will be easier to m~nllf~cture and handle. Another object is a simple and cost-effective method of m~n~lf~.turing such a semifinished web or plaster-impregnated wall covering.

The first object is attained in accordance with the present invention in a semifini~hed web or plaster-impregnated wall covering of the aforesaid type by the characteristics recited in the body of claim 1.

The present invention has many advantages. The elastic layer or layers of softener applied to the flexible base result in a web that can, like wallpaper, not only be unrolled but slit, sheared, and attached. The rolls can be trimmed into smooth strips that extend from the top to the bottom of the wall being covered. Ceilings can also be similarly covered, primarily because of the elastic layer of mineral-loaded softener. The coating will set as it dries but will not harden like a conventionally rigid mortar in that it is a blend of mineral substances and dispersed plastic. "Dispersed plastic" is an overall term for a dispersion of freely distributed plastics in a usually aqueous medium. Most of the dispersing occurs in l S the liquid phase. Once the dispersion has cured, the individual mineral particles are encapsulated and connected by bridges. This provides the layer of soft mineral-loaded plastic with flexibility and results in the aforesaid advantageous properties of rollability, convenient h~n(lling, etc.

The wall covering can be as wide as conventional wallpaper, or between 400 and 1250 mm. When in the form of a board, the covering can measure between 300 mm2 and 1250 x 2500 mm. The finished size depends on the particular application. Attaching such a covering in the form of a sheet or board to a wall ceiling will also provide heat insulation.
The surface will be very smooth and will resemble plaster. The "plaster" can be smooth or textured. The structure will leave the joints between adjacent sections invisible. Any constantly working gaps in the wall or wall surface can accordingly be effectively covered.
The covering can be either permeable or impermeable to water, depending on the application.

The base can be a sheet of plastic, paper, or fabric.

The particular type of sheet employed depends on its thickness and permeability.Permeability in particular constitutes a parameter for perforations in the sheet. These perforations can be stamped out of water-permeable or water-impermeable sheet. They can also be constituted by the interstices in a loose-woven fabric.

The most appropl;ate fabrics are non-wovens. Non-wovens are made of loose filaments of glass, polypropylene, polyester, thread, paper, viscose, or other natural or artificial fibers, generally bonded together by inherent adhesion and depending on how they are m~nlJf~ctured. The individual fibers can either have a preferred orientation (parallel or transverse) or not (swirled).

The non-wovens can be mechanically reinforced by needling, meshing, or swirling. They can also be reinforced by fastening the fibers together with liquid binders (dispersions of acrylate and polymer, SBR and NBR, or polyester and polyurethane), by fusion, or by the dissolution of what are called binding fibers blended in during m~nl~f~cture.

When non-wovens are consolidated, the surfaces of the fibers are etched with appLopliate chemicals and either pressed together or fused at a high temperature.

It has surprisingly been discovered that boards of spin-woven polyester (PES) fibers are applopliate for such plaster-impregnated wall coverings. Such products are not toxic and contain no preparations. They can be processed at up to 300 ~ C. They are porous enough to permit the permeation of air and hence of the coating.

The recipe for the artificial-resin mortar employed for such a coating is important.
The liquid portions have essentially two constituents. One component can be an elasticizer that accounts for 10 to 45 % and preferably 22 % of the mortar's overall mass. The elasticizer can contain at least 80 to 90 % by weight of a dispersed copolymer of butyl acrylate and styrene, preferably 57 % in water, and 0.5 to 2 % of dispersed paraffin, preferably 30 % in water. The other component can comprise 3 to 4 and preferably 3.7 %
of all the water in the mortar by weight. The first elasticizer component renders the cured mortar elastic and ductile, allowing the finished plaster-impregnated wall covering to be handled like wallpaper, in that it can be unrolled, trimmed, stretched, cemented, and torn.

The second elasticizer component, which can be water, renders the mortar fluid, prevents' it from curing too rapidly, and accordingly facilitates its handling. The mortar can contain 1 to 15 and preferably 3.7 % of the second elasticizer component by weight.

The artificial-resin mortar can contain:

% by volume Components 40 - 95 aqueous binder 5 - 50 latent aqueous binder 0 - 20 filler 0.1 - 5 hydrophobing agent 0- 10 silicate 0 - 10 dispersant 0 - 5O liquefier 1 - 3 stabilizer in powdered forrn.

To these components can be added:

% by volume Components 0 - 5 reaction retardant 0 - 5 setting accelerator 0 - 3 thickener 0 - 5 foamer The aforesaid formulations make it possible to provided the plaster-impregnated wall covering's artificial-resin mortar with its processing properties and characteristic look.

The dispersant, liquefier, and stabilizer consist of a plastic, specifically a vinyl acetate.

Coloring can be blended either directly into the powder or later into the mixed artificial-resin mortar. The coloring can be a light-colored pigment, especially a conventional white. The layer of mortar can be colored while the pigment is being added.
15 Since cement is usually dark gray after setting, the color of the layer of mortar can be lightened by adding even enough white coloring or pigments to render it white or almost white. The colorings can simultaneously supplement or improve the mineral substances or plastics in the mixture. Once such a colored mortar is hard, it will need only one coat of paint. The light-colored and almost white layer of mortar will also show through the paint 5 considerably and improve its appearance.

A woven support can also be embedded in one of the coats of artificial-resin mortar. Such a support can be a thin tissue of slender fibers. Such a layer will make the surfaces as easy to handle and process as those of l~min~ted board, and they can be plastered, wallpapered, or covered with fabric.

One or more heating devices, electric wires for example, can be applied to or embedded in one of the coats of artificial-resin mortar. Such wires can be applied to an outer surface and pressed into the mortar.

The artificial-resin mortar can be sprayed or brushed onto the surface of the web.
Such an approach can produce a very thin layer, only 0.01 to 0.1 thick. A two-component 15 mortar can also be rolled or painted on. The particular mode of application depends on how thick the layer of mortar is intended to be.

The other object of the present invention is a method of m~nllf~cturing such a semifinished web or plaster-impregnated wall covering whereby:

A) a flat and at least to some extent flexible base is advanced over a rotating 20 flattener at a speed of 1 to 15 m/min, B) a mineral-loaded dispersion of plastic is applied to one of the sides of the base from a combination mixer and tank at a spread of 100 to 350 mm, C) the mineral-loaded dispersion of plastic is scraped into a smooth coat with adoctor, D) the base, accordingly coated on at least one side, is forwarded at 1 to 15 m/mm through a drying section by an air-permeable linked-bar conveyor belt to set the dispersion, and E) the resulting semifini~hed web is kept ready in a storage device.

The method in accordance with the present invention has several advantages.
Such a semifini~hed web or plaster-impregnated wall covering is easy to m~nuf~cture continuously. It is significant that the dispersion is applied at a spread of 10 to 350 mm.
Spread is employed in the construction industry as a measure of the flow or viscosity of a 5 mortar. Wall mortar for example has a spread of less than 120 mm. It has surprisingly been discovered that, when non-wovens with an air permeability of 4 to 6000 l/m2 sec are employed as bases, an artificial-resin mortar with an elasticizing component in the form of a mineral-loaded dispersion of plastic will have a spread of 160 to 210 mm. A mortar with such a spread will spread more easily and flatter over the surface of the non-woven as well 10 as penetrate into its pores as intended. With the base moving at the discovered optimum of 1 to 15 and preferably 5 m/min, the mortar's depth of penetration and extent of permeation can be regulated. Removing the excess mortar with the doctor to a desired depth precisely establishes the layer's thickness. The mortar will set at the same forward speed as the coating, ensuring a steady forward motion on the part of the base. The temperature and 15 length of the drying section ensure a predictable drying rate and hence industrial-scale m~nuf~cture. The air-permeable conveyor ensures all-around drying and hence rapid and complete setting of the mixture. Storing the final semifini~hed web or plaster-impregnated wall covering keeps it ready for shipment. Essential to the present invention is that the method known from German Patent No. A 4,239,269 is partly exploited for the new and 20 improved method. The fundamental steps of the method allow the m~nllf~cture of the final plaster-impregnated wall covering product as intended.

The spread can be monitored continuously or at intervals of 10 minlltes or of one or three hours during step B). A measured volume of liquid component can be fed to the tank and removed at a specific rate to maintain the spread within specified limits. This 25 measure will ensure plaster-impregnated wall coverings and surfaces thereof of constant quality.

Coloring can also be added to the mineral-loaded dispersion of plastic during the same step. The coloring will conveniently diffuse and dissolve as the lni~ e is prepared.

The accumulating mineral substances and the dispersion of plastic can be detected 30 with a sensor in the following step C) and exploited as a parameter to regulate how much of the mixture to introduce.

The signal that represents the accl~m~ ting mortar and the signal that represents the spread can be forwarded to controls. The controls can be computerized. The output signal can be employed to regulate the supply of liquid and mixture.

The doctoring off of the excess mortar can be exploited to provide the still moist 5 layer with a texture. The texture need not be that of the doctor. Generally, however, the doctor will leave the moist layer smooth and flat. Between steps C) and D) on the other hand, the moist layer can be provided with a specific texture by means of a texturing device. Such textures can imitate those of plaster, wallpaper, etc.

The mineral-loaded soft plastic layer can be cured with infrared radiation during 10 step D). It has surprisingly been discovered that such radiation is especially useful fort accelerating setting subsequent to coating. The radiation will cause the mixture to set so rapidly and effectively that it will be resistant to pressure in as soon as 5 to 25 minutes.

The bonding of the mineral-loaded dispersion of plastic can be promoted by flushing with air from below. This is done by flushing with warm air the side that is not 15 actively coated. The process can even be accelerated with infrared radiation. It is useful for the coated base to be dried from both above and below with infrared radiation or hot air to control the bonding rate.

In step E) the semifini.~hed web can either be rolled up or trimmed to length. How the resulting product is to be stored depends on how it is to be shipped and handled.

It is of essence to the present invention, however, that rolling the semifini~hed web up will at least advance the base, especially where it is coated on one side, and hence adjust and regulate the speed of advance. Since rolling up the final product will conveniently stretch the unllill~llled base, the speed can be controlled very much as intended.
One embodiment of the present invention will now be specified with reference to the accompanying drawing, wherein:
Figure 1 is a schematic illustration of part of a plaster-impregnated wall covering m~nllf~ctured from a web of non-woven;

Figure 2a is a section through part of the plaster-impregnated wall covering illustrated n Figure 1 along the line IIA-IIA;

Figure 2b is a larger-scale detail of the area IIB in Figure 2a;

Figure 3 is a schematic side view of a device for carrying out the method of 5 manufacturing the plaster-impregnated wall covering illustrated in Figures 1 through 2b;

Figure 4 is a schematic top view of the device illustrated in Figure 3;

Figures 5a and 5b illustrate instruments for me~curing the spread of a mortar inaccordance with DIN 1045; and Figure 6 is a schematic perspective view of part of an interior wall covered with a 10 heat-insulating wall covering.
Figure 1 illustrates a web 2 for a plaster-impregnated wall covering 100 or 101.Web 2 is made of spin-woven polyester fibers, specifically polyethylene terephth~ te with a thermoplastic polymer added to it. The web has pores 22 and fibers 23.

It has surprisingly been discovered that a spin-woven web 2 with the following 15 specifications is the most practical for m:~nuf~cturing a plaster-impregnated wall covering 100 or 101.

Mass per unite of area: 57 < 64 < 70 g/m2 Connective portion: approx. 30 %
Thickness: approx. 0.20 m Tensile strength, longitudinal: 190 < 200 N per 5 cm Tensile strength, transverse: 130 < 140 N per 5 cm Type of glass: E-Glass Fiber diameter: 13.5 11 -Fiber length: 18 mm Air permeability: 5000 l/m2 s These characteristics can vary with a tolerance of ~10 %. The web 2 can be rolled up in lengths of approximately 2500 m to a diameter of approximately 77 cm.

Of special significance to the further handling of the particular web 2 employedare its weight per unit area, its titer, and its permeability to air. "Titer" is a term employed in the textile industry as a measure of fiber and filament fineness, their weight per length, that is, and is expressed in terms of "tex". A titer of 1 to 10 Dtex and preferably of 4 to 6 5 Dtex can be employed instead of the weight per unit of area. In describing the tolerance range for either g/m2 or Dtex, either can be converted to represent the lowest and upperrnost threshold.

Air permeability is a measure of the porosity of web 2. Pores 22 extend all the way through from one side 21 to the other side 24.

An artificial-resin mortar 11 is applied to the aforesaid woven web 2.

The composition of mortar 11 will now be specified in terms of parts A), B), andC).

A) 1000 g (74.1 % by weight) of powdered components in the form of very fine-grain cement and additives, specifically:

% by volume Component 40 - 95 aqueous binders 5 - 50 latent aqueous binders 0 - 20 filler 0.1 - 5 hydrophobing agent 0 - 10 silicate 0 - 10 dispersant 0 - 5 liquefier o - 3 stabilizer plus optionally:

0 - 5 reaction retardant 0 - 5 setting accelerator 0 - 3 thickener 0 - 5 foamer.

B) 300 g (22.2 % by weight) of elasticizer, specifically 80-90 % by weight of a 57 % dispersion of a copolyrner of butyl acrylate and styrene in water, and 0.8 - 2 % of a 30 % dispersion of paraffin in water.

Elasticizers of similar composition are known. They can be employed to elasticize cement, lime, and plaster products to make them ductile. Essential to the present invention is that the specific elasticizers be more effective then known elasticizers and that the addition of 300 to 1000 g of powdered component will have a positive effect on the h:~n(lling and processing of mortar 11 and of the wall covering 100 or 101 that employs it.

C) 50 g (3 .7 % by weight) of water.

Adding this amount of water improves the h~n(llin~ properties of the mixture of components A) and B). Coloring can also be added to the mixture. Any coloring can be employed. A very dark mortar can be advantageously be lightened, however, by adding white until it is entirely or almost white. One measure of the mixture's processing 15 properties is spread A, which will be specified later herein.

The foregoing specifications must be skillfully observed. They may deviate ~ 25 % without depriving the accordingly mixed artificial-resin mortar 11 of any essential properties. The specified mixture is intended for the hereintofore specified non-woven web 2.

An artificial-resin mortar of the aforesaid composition is, once has been well blended, applied to non-woven web 2. Since the web is part of a 2500 m roll, mortar 11 can be applied continuously to it.

Due to the aforesaid specifications for web 2 and on the flow capacity of an artificial-resin mortar 11 of the aforesaid composition, it has surprisingly been discovered that, when the mortar is applied to side 21, not only that side but the other side, side 24, as well will also be coated. As side 21 is coated, that is, mortar 11 will penetrate through pores 22 and at least partly surround fibers 23 as illustrated in Figure 2b.

How much artificial-resin mortar 11 is to be applied to side 21 is determined in a continuous process by how fast and how much mortar is available. The penetration of the pores 22 and the occurrence of mortar on side 24 will procéed at the same rate. The thickness of the coating can be affected by the number of applications. How the mortar is 5 applied will also allow the creation of surface textures that will assist the processing of wall coverings 100 or 101 and render the joints almost invisible when the covering is attached to the wall.

Non-woven web 2 has a "filtering" effect that, when artificial-resin mortar 11 is applied to only one side 21, essentially retains the coarser particles of the mortar on that 10 side while allowing the finer ones, especially the resinous particles, to penetrate to other side 24. The slenderness of pores 22 and the screening of the powder components,especially the cement and sand-sized grains, determines what solids can penetrate to the other side. The proportion of water in the three-component mortar 11 increases it brushing capacity and allows the coating to be smoothed on both sides.

As artificial-resin mortar 11 dries, it creates a flexible coat 1 on side 21 and a flexible layer 3 of impregnation at least in pores 22, possibly along with another coat 1' on side 24. Layer 3 constitutes a series of "points" over wall covering 100 or 101 that bond to the mortar and connect flexible coats 1 and 1' together. In other words, non-woven web 2 will be at least to some extent both surrounded by and saturated with the hardened mortar.

Figures 3 and 4 illustrate a device for manufacturing wall covering 100 or 101.

A roll 41 of non-woven is mounted at the entrance to the device, and a web 2 unrolled from it over web-advance controls 42. Web-advance controls 42 constitute a rotating cylinder 43 secured in a frame 44. It is essential to the present invention that cylinder 43 can rotate freely around its axis such as to ensure that web 2 will travel straight along a flat surface 48. Before arriving at surface 48, however, web 2 travels over feed cylinders 45 and 46. The web is then laid against the surface by a pressure-application cylinder 47.

Flat surface 48 is constituted by a continuous and liquid-tight conveyor belt 49that travels around rollers 50 and 51, one of which is powered. Web 2 advances at a speed v of between 1 and 15 and preferably 5 m/min, and, since conveyor belt 49 travels at the same speed, flat surface 48 moves along with the web.

An artificial-resin mortar 11 is applied to web 2 from a combination mixer and tank 52. A doctor 53 removes excess mortar and establishes an average thickness for what will be a flexible coat 1 of mortar. The doctoring produces an accumulation 13 of mortar upstream of doctor 53. Accumulation 13 is measured with a sensor and exploited as a parameter for how much mortar 11 will be supplied.

Not only the accumulation 13 of mortar 11, however, but also its spread A is measured in accordance with DIN 1045 by the means illustrated in Figures 5a and 5b.
10 These means comprise a glass plate 71 and a Vickert ring 75. Glass plate 71 is square, with edges 72 and 73 300 mm long and a thickness 74 of 5 mm. A Vickert ring 75 is an instrument in the form of a hollow truncated cone with an upper inside diameter 76 of 70 mm and a lower inside diameter 77 of 80 mm. The ring has a thickness 78 of 2.5 mm and an altitude 79 of 40 mm.

How spread A is determined will now be specified. Vickert ring 75 is positioned at the center of glass plate 71. Enough mortar 11 is introduced from tank 52 to entirely occupy the ring. The ring is then lifted and the mortar allowed to spread over the plate.
The spread A of mortar 11 is considered as ranging from a minim~l diameter of 150 to 180 and preferably 170 at a height of 5 to 10 and preferably 6 to 8 mm to a maximum of 190 to 20 215 and preferably 205 at a height of 2 to 7 and preferably 4 to 6 mm. The minim:~l and m~im~l spreads A indicate that a very fluid artificial-resin mortar has spread out very far at an already considerable thickness. Spread A can be regulated by regulating the proportion of liquid component, especially water, in the mortar. Tank 52 is not just a tank but serves to both prepare and store mortar 11. A specific amount of coloring can be added 25 and blended in while the mortar is being mixed to provide it with a desired color. A signal representing spread A can also be forwarded to controls 42 to allow continuous processing.
The particular spread employed should ensure that mortar 11 has attained, before arriving at a texturing device, enough hardness, although still moist, to retain any textures established on its surface. The texturing device can be a robot with a comb 56 on the end 30 of an arm 55, producing a pattern, adjacent arcs for example, in what then becomes a textured-mortar coat 12.

As mortar 11 is applied and doctored, it will diffuse into the pores 22 in web 2.
The speed of web 2 and the hardening time and spread of mortar 11 determine to what extent the mortar, especially any small particles it contains, can penetrate along with its plastic constituent to the other side of the web.

The accordingly coated and saturated web 2 proceeds to a drying oven 62, where it travels over an air-permeable grated device 57 in the form of a continuous air-permeable linked-bar conveyor belt 58 that travels around deflection cylinders 59 and 60. The bars in conveyor belt 58 are supported on strands of chain and the coated web 2 on the bars. Belt 58 is synchronized with belt 49, and the coated and saturated web travels through drying oven 62 at the same speed v it is coated at.

Drying oven 62 accommodates radiators 63, sources of infrared radiation in accordance with the present invention. The radiators, preferably hot-air blowers, accelerate the curing of the plastic component of artificial-resin mortar 11. The curing is also promoted by driers 61 under belt 58. Driers 61 can also be backed up by sources of infrared radiation. The length of drying oven 62 depends on the particular drying time.

Coated web 2 leaves drying oven 62 in the form of a finished plaster-impregnatedwall covering 100 or 101.

Once artificial-resin mortar 11 has set, there will be a flexible coat 1 over the upper side 21 of web 2, a layer 3 of impregnating mortar in pores 22, and another flexible coat 1' over lower side 24. A dispersion 14 of plastic is distributed along with mineral substances 15 as hereintofore described as mortar 11 is applied. As the mixture sets, its regions 15 of mineral substances will be encapsulated in an adhesive envelope 17 and connected by adhesive bridges 16. The individual mineral regions 15 will accordingly be "linked" together and to the fibers 23 of non-woven web 2. This structure ensures the properties of flexibility and easy handling typical of the plaster-impregnated wall covering 100 or 101 in accordance with the present invention.

The finished wall covering 100 or 101 is rolled up under tension by a winder 65.Winder 65 comprises a drum 67 with a long enough inside diameter to prevent the wall covering from creasing or deforming as it is wound. Drum 67 is rotated by a mechanism 68 in the form of a speed-controlled motor by way of an applopliate multiplication-and-reduction tr:~n~mi~sion. Essential to the present invention is that wall covering 100 or 101 is wound into a roll 66 at the same speed v web 2 is advanced at. Regulated drive mechanism 68 accordingly simultaneously ensures that speed v will remain constant as the 5 diameter of roll 66 increases. To ensure continuous operation, the wall covering is rolled "on the fly", meaning that a full drum 67 is immediately replaced with an empty one. The exchange is accomplished by guidance-and-diversion mech~ni~m~ that allow a freshcovering to be advanced at speed v and immediately rolled up by further mech~ni~m~ A
tensioning cylinder 64 keeps web 2 correctly positioned even while wall covering 100 or 101 is being rolled up. Tensioning cylinder 64 can be raised or lowered along with the whole winding section or along with drum 67 alone.

The wall covering 100 or 101 on roll 66 has been sufficiently finished and "dried"
to prevent it from deforming when rolled up. Prior to further processing, however, it is of advantage to leave the roll alone until the chemical reaction is complete.

How wall covering 100 or 101 is further handled will now be specified with reference to Figure 6.

Figure 6 illustrates a room with a tiled floor 31 and a wall 30. Wall 30 is a slab of prefabricated concrete of the type employed in structures in the recently ~imil~ted German states. It is characterized by a large number of depressions in an otherwise smooth , 20 surface. This characteristic considerably complicates covering. Furthermore, wallpaper paste can accumulate in the depressions and spoil the appearance of the wall covering.

A web of plaster-impregnated wall covering 100 is accordingly applied directly to this raw surface. It is particularly convenient here to use the tools and materials of conventional house painting. The covering is trimmed as it is removed from the roll to the 25 height of the room. Side 24 or the coat 1' of mortar on it is provided with a dilute dispersion adhesive. The web is then attached to the wall like any conventional wall covering. Since side 24 or flexible coat 1' has an almost flat but rough surface, they provide the adhesive with an interface that facilitates adhesion.

The wall covering is brushed smooth and simultaneously pressed against wall 30 with a brush. Another web of plaster-impregnated wall covering 101 is then similarly trimmed to size, its back provided with adhesive, and attached to the wall. Wall covering 100 and 101 are attached edge to edge like a raw-fiber wall covering, providing the wall 5 covering with a smooth appearance. The texture introduced into coat 1 can help conceal the joints between the sections. Coat 1 can then be painted as desired, with its light coloring contributing to the effect of the paint.

Since coat 1 is heat-resistant, the wall covering can also act as an extended heating element if a network of electric-resistance wires is embedded in it, providing uniform heat 10 to the room when connected to a source of electricity. When such elements are combined with conventional in-the-floor heating, the room can be provided with a moderatetemperature gradient. Spaces that can benefit from such a treatment include operating rooms, laboratories, and facilities for raising such small animal as chicks and piglets. Such rooms, however, require not only very moderate gradients but also washable surfaces. The 15 easy-to-handle surface of flexible coat 1 is simple to tile or cover with some other type of washable material.

The embedded grid of electric-resistance wire will not only heat the space uniformly but will also act as a Faraday cage, keeping out electromagnetic waves.
Covering the walls of all types of space from laboratories to very high-tension test shops 20 will accordingly ensure uncont~min~ted measurements. It is essential to the present invention that the mesh of any grids embedded in the flexible coat be constant, 10 to 20 mm2 for example. This feature will elimin~te the need for cladding with expensive corrugated metal sheet or for metal ribbing under the plaster. The elec,tromagnet screening will be accompanied by high heat insulation, decreasing the expense of heating the space.

Plaster-impregnated wall coverings with embedded electric-resistance wires can also be employed in saunas and similar spaces. The wires will ensure uniform heat. The web 2 in the wall covering will not only insulate but will also, like the mortar itself, resist the prevailing high temperatures with no alteration in materials properties.

Claims

CLAIMS:

1. Semifinished web, specifically a plaster-impregnated wall covering with a flat and at least to some extent flexible base (22) and a flexible coat (1, 3) of a set coating on at least one side (21, 24) of the base, characterized in that the base has a thickness (D) of between 0.05 and 3 mm, in that the coat (1, 3) is of a set, mineral-loaded, flexible plastic composed while still in the form of an unset coating (11) of a) 40 to 95 % by weight of mineral substances and b) 5 to 60 % by weight of a dispersion of plastic in no more than 60 % by weight of water or other appropriate liquid.

2. Web as in Claim 1, characterized in that the base (2) is a sheet of plastic, paper, or fabric.

3. Web as in Claim 2, characterized in that the base (2) is a non-woven sheet of glass fiber.

4. Web as in one of Claims 1 through 3, characterized in that the coating (11) is an artificial-resin mortar composed prior to setting of 50 to 90 % by weight of powdered component in the form of finest-grain cement and finest-grain additives and 10 to 50 % by weight of liquid component with elasticizing properties, whereby the mortar after setting constitutes at least one coat (1, 1') of mineral-loaded plastic on one of the sides (21, 24) and a layer (3) of impregnation in the air-permeability interstices (pores 23).

5. Web as in one of Claims 1 through 4, characterized in that the liquid component is at least partly composed, first, of 10 to 45 % by weight of one or more elasticizing components, preferably a dispersion of 80 to 90 % by weight of a copolymer of butyl acrylate or styrene in water blended with 0.5 to 2 % by weight of a dispersion of 20 to 50 % by weight of paraffin in water and, second, of 1 to 15 % by weight of water.

6. Web as in one of Claims 1 through 5, characterized in that the powder component of the dispersion is composed of:

% by volume Components % by volume Components 40 - 95 aqueous binder 0 - 50 latent aqueous binder 0 - 20 filler 0.1 - 5 hydrophobing agent 0 - 10 silicate 0- 10 dispersant 0 - 5 liquefier 1 - 3 stabilizer

7. Web as in one of Claims 1 through 6, characterized in that the powder component of the artificial-resin mortar (11) contains:

% by volume Components 0 - 5 reaction retardant 0 - 5 setting accelerator 0 - 3 thickener 0 - 5 foamer.

8. Web as in one of Claims 1 through 7, characterized by a woven support embedded in one of the coats (1 1') of artificial-resin mortar.

9. Web as in one of Claims 1 through 8, characterized by one or more heating devices applied to or embedded in one of the coats (1, 1') of artificial-resin mortar.

10. Method of manufacturing a semifinished web, specifically a plaster-impregnated wall covering, characterized in that (a) a flat and at least to some extent flexible base (non-woven 2) is advanced over a rotating flattener (48) at a speed (v) of 1 to 15 m/min, (b) a mineral-loaded dispersion of plastic (artificial-resin mortar 11) is applied to one of the sides of the base from a combination mixer and tank (52) at a spread (A) of 100 to 350 mm, (c) the mineral-loaded dispersion of plastic is scraped into a smooth coat (1) with a doctor, (d) the base, accordingly coated on at least one side, is forwarded at 1 to 15 m/mm through a drying section by an air-permeable linked-bar conveyor belt to set the dispersion, and (e) the resulting semifinished web (100, 101) is kept ready in a storage device (65).

11. Method as in Claim 10, characterized in that the spread (A) is monitored during step B) and maintained at 100 to 300 mrn by regulating the portion of liquid component in the combination mixer and tank (52).

12. Method as in Claim 10 or 11, characterized in that coloring is added to the mineral-loaded dispersion of plastic during step B).

13. Method as in one of Claims 10 through 12, characterized in that the accumulation (13) of mineral substances and dispersion of plastic upstream ofthe doctor (53) is detected with a sensor during step C) and the portion of mineral-loaded polymer dispersion (11) added from the combination mixer and tank (52) is regulated in accordance with the extent of the accumulation.

14. Method as in one of Claims 10 through 13, characterized in that the still moist coat (1) is converted into a textured coat (textured-mortar coat 12) by a texturing device (54) between steps C) and D).

15. Method as in one of Claims 10 through 14, characterized in that the mineral-loaded dispersion of plastic (11) or at least the textured-mortar coat (12) is cured with infrared radiation during step D).

16. Method as in one of Claims 10 through 15, characterized in that the bonding of the mineral-loaded dispersion (11) of plastic is promoted by flushing with air from below during step D).

17. Method as in one of Claims 10 through 16, characterized in that the infrared radiation is applied to the textured coat (12) and the air from below to at least the side (24) of the base away from the textured coat.

18. Method as in one of Claims 10 through 17, characterized in that the semifinished web (100 or 101) is either rolled up or trimmed to length and stacked during step E).

19. Method as in one of Claims 10 through 18, characterized in that rolling the semifinished web (100 or 101) up will at least advance the base (2), especially where it is coated on one side, and hence regulate the speed of advance.