CS276535B6 - Plaster foamy material with a porous structure and process for producing thereof - Google Patents

Abstract

A gypsum foam (I) contains a polyurea (II) and has a density of 0.1-0.4 g/cm3. (II) is a condensation prod. of diphenylmethane-4,4'-diisocyanate prepolymers and contains water. (I) is open-celled and at least 80% of the pores have a dia. of 0.3-2 mm.

Description

The present invention relates to a gypsum foam having a porous structure and to a process for its manufacture.

Sound and thermal insulation materials are very important in the construction industry. Thermal insulation materials reduce energy consumption in buildings, thus reducing smoke emissions and contributing to environmental protection. Sound insulating materials are used in noise damping, building and residential acoustics.

As thermal insulating materials, mats, boards or fittings made of porous or fibrous organic and inorganic substances with low thermal conductivity such as coconut, wood, glass and mineral fibers or cork, gas concrete, foam plastics are used. As sound absorbing building materials, mineral fiber absorbers or other open-cell foams are used, which, depending on the circumstances, form an insulating layer on the foundations and do not form self-supporting building components on the subfloor, be used between components or incorporated into load-bearing structures.

The material must have a porous structure in order to absorb sound. This is the case for fibrous materials (for example glass or stone wool) or open-cell foams. The cells of the material are connected to each other (open pore structure) so as to allow air flow. In the absorbent material, a porous structure permits sound propagation, thereby converting the sound energy into thermal energy by local frictional losses at the fiber or cell edges.

Mineral fibers require high energy input when melting the starting materials - glass or basalt. The drawn fibers are glued to the desired thickness and density, and the adhesive is emitted to the surroundings for an extended period of time. The starting materials are available in sufficient quantities and are inexpensive. In the processing of fiber mats by shearing or sanding, short cuttings of fibers are produced which adhere firmly to the garment and cause itchy skin irritation as well as breathing disorders.

Also, plastic foams are not ecologically desirable, since a significant number of foams are strengthened using fluorochlorinated hydrocarbons (PCKW), these PCKWs substantially contribute to the ozone depletion.

Gypsum is an expanded building material in interior construction, which can be obtained from both natural materials and power plants from flue gas desulfurization (EEA) plants, where it falls out in large quantities.

Increasing efforts to clean air will increase the amount of EEA gypsum and will have difficulties in selling it. As a result, there is a need to market new gypsum products with extended properties beyond the known use of gypsum in the finishing process, floor, wall and ceiling panels. These include foam gypsum.

To date, commercially available gypsum with various additives such as aluminum powder, magnesium powder, by heating the mass to 300 ° C to 800 ° C have been prepared for the production of porous gypsum components. This results in gypsum foams with closed pores which can also be used as thermal insulators. These gypsum foams have the disadvantage that they are expensive to manufacture. In addition, they contain physiologically undesirable metals and require a considerable amount of additional energy to produce them.

U.S. Patent No. 4,330,589 discloses a gypsum gypsum product comprising a significant number of isolated cells, wherein the cell walls form fine channels connecting the cells. This foamed gypsum product is prepared by foaming a gypsum slurry containing hydrogen peroxide and a cobalt compound. The cobalt compounds used are physiologically unsuitable. An additional drying process at about 45 ° C for 6 hours is required during manufacture.

EP 0263975 discloses an open cell foamed gypsum which comprises a hydrocarbonaceous material and absorbs fluidic materials. This material is considered to be a filter material which is not expected to be used in acoustics and heat engineering.

DE-A-3804884 discloses an artificial stone which, inter alia, contains foam gypsum. This stone is also suitable as a thermal insulation material. However, it has the disadvantage that it is highly efficient. 276 535 B6, it is necessary to burn the furnace at high temperature.

DE 2546181 discloses a method for producing gypsum foam and gypsum foam building elements. The substances thus obtained have a porous structure and improved thermal insulation properties compared to conventional, non-foamed gypsum products. Its density ranges from 0.45 to 0.8 g / cm 2. In this known process, various additives must be used. The addition of gypsum liquefier is important. Sulfonic acid modified melamine resin, which is relatively expensive, is used as the gypsum liquefier. The gypsum / water mixture used in the known process has a relatively low viscosity and the product is liquid. It has the disadvantage of the formation of lumens and open, open spaces in the molds. Furthermore, the mixture has a processing time of only 5 minutes. This time is relatively short for manual processing and is not sufficient for practical use.

DE 2950785 discloses a gypsum foam which is produced as gypsum in DE 2546181 and further comprises polyvinyl alcohol and boric acid. This known plaster has the disadvantage that it contains boric acid, which is physiologically undesirable and, moreover, the difficulties mentioned in connection with DE 2546181 in the production of foam.

DE-OS No. 2250611 relates to a method for producing expanded, reinforced structural materials for building boards with advantageous compressive, tensile and flexural strength. These materials also have favorable properties for sound absorption and thermal conductivity. The K-factor reported in Example 3 is not comparable to the known thermal conductivities because there are no physical units of measure.

The specific size reported in Example 4 is unknown, comparison is not possible. Building boards have been prepared between reinforcing paper cover sheets, which can significantly affect sound absorption properties.

DE 2716918 discloses gypsum compositions comprising gypsum and resin foam powder. Plasters, gypsum cardboard boards, putty, modeling and filler materials are made from these plaster materials. The use of these products for acoustic and heat engineering purposes is not mentioned.

Utility Model G Application No. 8313354.2 discloses seam closures having a foamed gypsum of anhydrous porous cellular structure. These products are not suitable as heat insulating and sound absorbing materials.

It is an object of the present invention to provide sound-insulating materials and heat-insulating materials which exhibit good heat-insulating or sound-absorbing properties. It is a further object of the present invention to provide a method for producing a thermal insulating material. No high temperatures are required for its manufacture. They can be manufactured without high energy costs. The insulating materials do not contain short fibrous chips, which could cause unpleasant reactions such as itching of the skin or breathing disorders. The material should be cheap and hygienically acceptable.

According to the invention, a method for using gypsum, in particular BEA-gypsum as a base material, is to be found.

The present invention is based on a gypsum foam having a porous structure comprising a polyurea, characterized in that its specific weight is in the range of 0.1 to 0.4 g.cm ^- has open cells and contains the condensation product diphenylmethane-4 as a polyurea. , 4-diisocyanate prepolymer and water.

The invention also provides a process for producing a gypsum foam material, characterized in that gypsum is wetted with water, the resulting slurry was added 4,4'-diphenylmethane -diisokyanátový ^of prepolymer and crosslinker, the mixture was thoroughly mixed, transferred to a desired form and cured .

As the gypsum, all the neutral or weakly acid-reacting, water-binding calcium sulfate modifications in the conventional powder coating can be used in the present invention. Gypsum commercially available with a gypsum-water factor of 0.3 is preferably used. It is particularly preferred to use 4-gypsum or BEA-gypsum. BEA-gypsum is produced from a flue gas desulfurization plant. BEA gypsum is a wet dihydrate which, however, may also exist as semi-hydrates depending on the amount.

CS 276 535 B6.

According to the invention, the gypsum is mixed with a diphenylmethane-4,4'-diisocyanate prepolymer. The diphenylmethane-4,4'-diisocyanate prepolymer has the particular advantage of being solvent-free, as the prepolymer provides a stable NCO content and has a monomer amount below 0.5%. It is preferred to use a product having an NCO content in the range of from 12 to 20 wt%, preferably 14 to 18 wt%. Such products are commercially available. These products have a viscosity at 20 ° C of 10,000 mPa · s ¹ + 2,000.

The diisocyanate prepolymer reacts with water which is used to distribute the gypsum and crystalline gypsum water in a known manner to form a carbamic acid derivative which is converted to the primary amine with the cleavage of carbon dioxide. The primary amine is reacted with an isocyanate to give a urea derivative, preferably an ureide, which may optionally be reacted further. In the present invention, the term polyurea includes the condensation products of diphenylmethane-4,4'-diisocyanate prepolymers and water. The gypsum foam according to the invention has a specific gravity in the range of 0.1 to 0.4 kg.cm &^lt; ³ >, preferably 0.15 to 0.35 g.cm &^lt; ^{3 &gt};, particularly preferably 0.2 to 0.3 g.cm &^lt; ³ > ” ³ . It has open cells and contains at least 80% of cells between 0.3 and 2 mm in size. It is preferred that as many cells as 0.8 to 1.2 mm in size are present in the gypsum foam of the invention.

The gypsum foam according to the present invention comprises 53.5 to 88.5 wt. % of gypsum and 43.5 to 8.5 wt.%, a condensation product of diphenylmethane-4,4'-diisocyanate prepolymer and water as polyurea 0.1 to 2.0 wt. crosslinking agents such as alkylphenol oxethylate. It is not necessary for the gypsum foam according to the invention to contain further additives, but may optionally contain conventional additives in an amount of 0.1 to 2% by weight. based on the dry weight of gypsum, polyurea and crosslinking agent.

In the preparation of the gypsum foams according to the invention, the gypsum, preferably gypsum, is moistened with water, to which the diphenylmethane-4,4'-diisocyanate prepolymer and the crosslinking agent are added. Mix thoroughly. The mixture has a working time of 10 to 15 minutes. After mixing, it is converted to the desired form and allowed to cure. Curing takes place at room temperature for 30 minutes to 2 hours. After curing, the material can be removed from the mold. Further curing, which may take place in or out of the mold, is completed within 8 to 12 hours.

According to the invention, the mass blend is mixed. 50 to 70%, preferably 55 to 66% gypsum, 10 to 25, preferably 15 to 25% water and 10 to 30%, preferably 15 to 25% diphenylmethane-4,4'-diisocyanate prepolymer and 0.1 to 2.0 %, preferably 0.1 to 1 wt. crosslinking agent.

Known cross-linking agents, i.e. commercially available products such as fatty alcohol sulfonates, quaternary ammonium compounds, as well as other cationic, non-ionic and anionic agents can be used as crosslinking agents according to the invention. Specific examples of crosslinking agents are ethylene oxide / propylene oxide polyglycol, betainsiloxane surfactant, low molecular weight acrylic copolymer and alkylphenol oxethylate. This compound is preferred. Crosslinkers affect curing and elasticity. They are used in amounts of from 0.1 to 2 wt. %, preferably in amounts from 0.5 to 1.0 wt.%, particularly preferably in amounts of 0.5 wt. They are used to control pore size. the higher the proportion of crosslinker, the smaller the pores.

The gypsum foam of the present invention will be used as a sound insulating and / or heat insulating material. In a preferred embodiment of the invention, the prepared gypsum slurry is converted into special molds and foamed therein so as to obtain specially shaped building elements. It is particularly advantageous to treat the gypsum foam according to the invention in a preformed rugged system or to use it as acoustic ceiling or wall components (also under protective masonry or wall coverings). It is also possible to produce plates, tubes and elements of various shapes. The gypsum foam according to the invention is adhesive, it is possible to place dowels and nails. Further mechanical processing by cutting, shearing, milling and brushing is possible.

This is particularly important when using gypsum foams as sound insulation materials. If the gypsum foam has a closed pore surface after the foaming is complete, the surface must be peeled to allow the pores to open. This can be done above

CS 276 535 B6 by mechanical means mentioned above. Several of these post-processing methods can be used on the same workpiece. For example, it is possible to brush the panels on the top surface and cut the sides.

The material that is removed during mechanical post-treatment can be reused. If it falls off in pieces, it can be crushed and eventually ground. The powder can then be admixed to the starting mixture of diphenylmethane-4,4 ^/ -diisokyanátových prepolymers, gypsum and water, and a crosslinking agent. It is also possible to admix 5 to 15 wt.%, Preferably 8 to 12 wt.%, Particularly preferably 10 wt. waste powder.

The material may also be film-coated or film-coated. This increases the mechanical load and thus regulates the resistance to water vapor diffusion (vapor barrier). If the film thickness is chosen appropriately, the acoustic properties will not be impaired, it can also be used in the form of sandwich boards. The process according to the invention can be carried out continuously or discontinuously. In a discontinuous embodiment, the obtained gypsum slurry is poured into molds, for example, crates. In the manufacture of sandwich panels, the board can be lined with a floor or cover plate. In a continuous process, for example, gypsum slurry can be introduced onto a continuous web, which is molded, and the belt is finally covered with a cover plate. This gives endless plates which can be cut or cut to desired shapes and dimensions as required.

The gypsum produced according to the invention has the following advantages:

The gypsum foam according to the invention has a very good sound absorbency. The degree of sound absorption for perpendicular sound impact (measurements according to DIN 52 215) for a 38 mm thick test specimen is given in Table I for the different frequencies. For comparison, the results of measuring an equally thick glass wool sample are given. ........

Table I Frequency degree of sound absorption «6 glass wool gypsum foam 100 Hz 0.18 0.14 200 Hz 0.20 0.21 400 Hz 0.49 0.46 800 Hz 0.77 0.76 1600 Hz 0.57 0.91 · 3200 Hz 0.65 0.89

It has excellent thermal insulation ability. The value of λ is 0.045 W / mK. Polystyrene foam and mineral wool have a thermal conductivity coefficient of λ = 0.035 W / mK to 0.05 W / mK. The material according to the invention is therefore extremely valuable. Compared to known building materials, it has a significantly lower specific gravity. Known gypsum foams have a density from 0.6 to 0.7 g.cm ^- third gypsum foam according to the invention therefore allows for easier handling, especially during handling and transportation, which for practical use of great importance.

The gypsum foam according to the invention can be glued, dowels and nails can be placed therein, the mechanical post-processing is carried out by cutting, cutting, milling and brushing.

The method of the present invention has the following advantages:

It is not necessary to use other additives besides gypsum, isocyanate and crosslinking agent, in particular no metals. There is therefore no harm to the environment. In the process according to the invention, the addition of gypsum liquefier is not required. Therefore, the process according to the invention can be carried out at a higher viscosity of the gypsum-water slurry, thereby avoiding leacher and mold effluent. The processing time in the process according to the invention is at least 10 minutes, at most 15 minutes. This time allows the processor to carry out the basic mixing, converting the mixture into a modified mold without fear of premature curing.

CS 276 535 B6

It is not necessary to use a gypsum liquefier. Metal compounds which, as mentioned above, are physiologically undesirable are used as gypsum liquefier in the known methods.

In contrast to known methods, it is not necessary to heat the gypsum distribution water. This means that even small businesses and plants can operate in a simple manner according to the present invention without having to have complicated equipment in their plant.

In the process according to the invention, it is not necessary to use, as in DE '2546181 describing the known process, another foaming agent, such as fluorocarbon. The use of fluorocarbon is harmful to the environment. The process according to the invention allows the sophisticated use of waste RBA gypsum and allows the production of the necessary building materials.

The method according to the invention is very inexpensive because expensive devices requiring more energy and labor are not needed.

The following examples illustrate the invention in more detail.

Example 1

66.5 wt. 16.5 wt. parts of water. 16.5 wt. parts of diphenyl-4,4 ^{from a} solvent-free isisocyanate prepolymer having an NCO content of 16% by weight; and 0.5 wt. nonionic alkylphenol oxethylate as crosslinker.

The whole mixture is thoroughly mixed and converted to the desired form.

The reaction starts after about 10 to 12 minutes and is complete after about 1 hour. The product obtained is a board with good surface hardness.

Example 2 wt. 4 parts of gypsum are mixed with 21.5 wt. parts of water and 0.4 wt. parts of a crosslinking agent, which is a commercially available alkylphenol ethoxylate and with 13.1 wt. parts by weight of diphenyl-4,4 ^{from a} diisocyanate prepolymer having an NCO content of 16% by weight; The total mixture is mixed thoroughly and converted to the desired form.

The reaction starts after 10 to 12 minutes and is complete after about 1 hour. The product obtained is a board with good surface hardness.

Example 3

The procedure is as in Example 1 and the following components are used:

59.4 wt. «C-gypsum

15.0 wt. water

16.0 wt. % diphenylmethane-4,4-diisocyanate prepolymer with an NCO content of 16% by weight;

0.4 wt. % of a cationic fatty amine salt as a crosslinker 9.0 wt. reacted residual plaster.

After mixing, the entire mixture is converted to a crate form. The reaction starts after about 10 minutes and is complete after about 1 hour.

Example 4 wt. parts of rf-gypsum are mixed with 20 wt. water and 0.5 wt. parts of a crosslinking agent, which is commercially available alkylphenol oxethylate, and 16 wt. parts by weight of diphenylmethane-4,4 ^{from a} diisocyanate prepolymer with an NCO content of 16% by weight; and 4 wt. parts of the reacted gypsum foam obtained according to Example 3.

After mixing, the entire mixture is converted to a crate form. The reaction begins in 1010 minutes and is black after about 1 hour.

The sheets and parts prepared in Examples 1, 2, 3 and 4 can be processed by shearing and cutting. The crusts formed on the surface during manufacture can be removed by milling, thereby affecting the sound insulation properties. Coating with various substances allows a special influence on the absorption properties according to frequencies. The parts can be provided with dowels and nails.

Claims (4)

PATENT CLAIMS Gypsum foam having a porous structure for soundproofing and thermal insulating materials, comprising polyurea and at least 80% of cells of a size of 0.0003 to 0.002 m, characterized in that it contains 53.5 to 88.5% by weight. gypsum in the form of gypsum dihydrate, 43.5 to 8.5 wt. the condensation product of diphenylmethane-4,4 ^/ -diisokyanátového prepolymer and water as polyurea, 0.1 to 2.0% by weight. % of a crosslinking agent, such as an alkylphenol oxethylate, and optionally 0.1 to 2.0 wt. other conventional additives, based on the dry weight of the gypsum, polyurea and crosslinking agent. 2. A method according to claim 1 wherein 50 to 70 wt. gypsum is moistened with 10 to 25 wt. of water, 10 to 30 wt. of diphenylmethane-4,4'-diisocyanate prepolymer and 0.1-2.0% by weight of crosslinker based on the total weight of the mixture, mixed, converted to the desired form and cured at normal pressure and temperature. 3. The method of claim 2, wherein the surface of the product obtained is treated by cutting, cutting, milling or brushing, or more. 4. A process according to claim 2 or 3, characterized in that the shredded, cut, milled or brushed material is admixed, optionally after comminution and / or grinding, with a mixture of gypsum, water, diphenyl-4,4 ^{from a} diisocyanate prepolymer and a crosslinker. reagents.