FI65416C - FOERSKUMBAR MAGNESIACEMENTBLANDNING - Google Patents

Description

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(32) (33) (31) Privilege requested — Buglrd prlorltet (71) Bayer Aktiengesellschaft, Leverkusen, Federal Republic of Saxony-Förbundsrepubliken Tyskland (DE)! (72) Hans Kyri, Cologne, Federal Republic of Germany-Förbundsrepubliken 'Germany (DE) (7 ^) Oy Kolster Ab I (5 * 0 Foamable magnesia cement mixture - FÖrskumbar magnesiacement- blandning »f *

The present invention relates to a hydrogen peroxide foamable magnesium cement mixture having the formula Mg Cl2-5 Mg (OH) 2.8 H2 ° '

Magnesium cements, based on both magnesium sulfate as well as magnesium chloride and magnesium oxide, have long been known. After the raw material mixture has hardened, the solids obtained correspond to the formula

MgCl2.5Mg (OH) 2.8H2O or equivalent magnesium oxysulphate. Excess soluble magnesium salt should be avoided as it will cause bubbles in the solid formed. Excess water is removed from the solids after curing by drying or suction. It is known to add calcined magnesite to these mixtures, which is prepared by firing natural magnesium carbonate at a temperature of 800-900 ° C.

2 6541 6 For compositions containing less water and thus also viscous, the relationship between the pore formation rate and the curing rate of the composition must be known precisely in the flotation. At the end of gas evolution, the composition must be cured to such an extent that the foam structure is self-supporting. According to the current understanding, the foamed mass is not shaken or mixed, because this causes, at least in part, the destruction of the foam structure. (O.Ettei, Bauplanung und Bautechnik, 6, vintage, booklet 7, pages 171-174, 1952).

U.S. Patent No. 3,989,534 discloses a lightweight, foamed cement composition made from (a) mineral cement such as gypsum cement, Portland cement, calcium aluminate cement, or magnesium cement, (b) light mineral materials such as perlite, vermiculite, or onto per 100 parts of cement, (c) a film former and a foam stabilizer, which may be either organic film formers such as guar gum and / or collagen protein colloids, or inorganic film formers such as bentonite or montmorillonite in an amount of about 1 part Per 100 parts of cement, (d) a synthetic surfactant, which is preferably a combination of anionic and nonionic surfactants in an amount of about 0.1 to 3.0 parts per 100 parts of cement, (e) water used from 30 to 150 parts per 100 parts of cement, and (f) from air derived from the cement composition such that the volume of the cement increases by 5-400%, preferably by 20-200%.

For example, in the construction industry, there is a need for inorganic, foamable masses that can be treated while fully preserving the foam structure by brushing, pressing, or spraying into molds or cavities and curing upon bonding at room temperature to a hard, porous body. Particularly preferred is an inorganic and thus non-combustible, porous material which, on the basis of its processing properties, is fully formable by means of treatments for organic foam materials.

To date, the rigidity of the foam has caused problems, because, for example, when filling from a cavity, such as cable openings, it is often not possible to coat the space to be filled in a liquid-tight manner. The density of the required mass must thus correspond approximately to a mortar which does not flow out of such a cavity.

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Similar requirements are also imposed on porous refractory plasters which are applied as fire protection compounds to supporting steel structures in buildings in order to slow down the heating of the steel structures in a fire.

The foamable inorganic masses used so far are either easily flowable and so stable that they can be cast into molds, which require very high requirements for the tightness of the joints to prevent the foamed mass from flowing out, or are very rigid but unstable. cannot be formatted.

The magnesium cement compositions of the present invention contain 12.5 to 16% by weight of magnesium chloride, 35 to 45% by weight of calcined magnesite, 35 to 40% by weight of water, up to 0.1% by weight of wetting agent, 3 to 25% by weight of clay and / or kaolin, 0.005 to 0.15% by weight of cellulose or water-soluble proteins and optionally up to 15% by weight of additives.

Porous moldings based on magnesium cement are prepared by thoroughly mixing magnesium chloride, calcined magnesite, water and, if desired, wetting agent and additives with a) cellulose ethers and / or water-soluble proteins and b) kaolin and / or clay and foaming with 0.1-1 weight percent of hydrogen peroxide. Preferably the foamable magnesium cement mixture contains 12.5 to 15% by weight of magnesium chloride 35 to 40% by weight of magnesite 35 to 40% by weight of water 0.001 to 0.1% by weight of wetting agent 5 to 15% by weight of clay substances and / or kaolin 0.01 to 0.15% by weight of cellulose ether or cellulose ether and, if desired, 0 to 15% by weight of additives.

Surprisingly, it has been found that the use of an organic thickener selected from the group consisting of cellulose ethers and / or water-soluble proteins together with an inorganic thickener selected from the group consisting of kaolins and / or clays results in a strong increase in the 4 6541 6 runoff limit in foamed magnesium cement mixtures. The viscosity measured by the mixing viscometer of both the non-foamed raw material mixture and the foamed mixture then corresponds, under similar conditions, to the viscosities obtained with the separate use of an organic or inorganic thickener.

According to the present invention, magnesium cement mixtures are foamed which, by adding together an organic and an inorganic thickener, are modified so that when foamed with hydrogen peroxide they give a rigid foam which no longer flows by gravity. Preferably, a magnesium cement mixture having a composition corresponding to the formula is prepared and foamed

MgCl2.5Mg (0H) 2.8H2O + X Mg (OH) 2 where X can have a value between 0 and 4.

The magnesium cement to be foamed according to the invention binds to a hard porous body which no longer needs to be dried. With such a mass, the cavities can thus also be filled and immediately closed.

Aqueous solutions of suspensions can be made viscous by the addition of water-soluble, high molecular weight compounds using, for example, natural or synthetic organic colloids. In the case of the present magnesium cement mixtures, the addition of these colloids is limited by the amount of water that these mixtures can absorb. In compositions that bind without excess water, the water content is determined by the above formula. Since the starting material is a solution of magnesium salts, the amount of water required to dissolve the colloids cannot be increased arbitrarily.

Cellulose ethers or protein products increase the viscosity of the pulps to be foamed. Nevertheless, the stiffened foams thus flow under the influence of natural gravity or when shaken. Thus, for example, when they are vibrated, they flow out of a gap about 2 mm wide into the mold. Although these foams already have a clear structural viscosity, their flow limit is low, i.e. they drain already under the influence of a small shear force.

Compared to other foamed inorganic suspensions, for example porous lime-sandstone, the stability of the foamed magnesium cement mixtures according to the invention, despite their high viscosity, is surprisingly so high that they can be applied or vibrated into molds without deteriorating the pore structure.

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If kaolin and / or clay are used to stiffen the magnesium cement mixtures, the viscosity of the liquid raw material mixture and the foamed mass clearly increases. The runoff limits of both systems, i. non-foamed and foamed, however, remain so low despite the relatively large increase in viscosity that these mixtures alone flow freely under the influence of gravity.

Surprisingly, raising the runoff limit by these measures mainly affects only the foamed mass. In addition, it has been found that foaming into rigid foams which do not flow freely can advantageously be carried out with raw material mixtures which, despite their high viscosity, do not have a significant flow limit.

Particularly good foams - for the purposes of this invention - are obtained with raw material blends with an upper flow limit according to the following test: a groove drawn to a homogeneously blended raw material mixture on a blunt pen with a depth of 10 mm must automatically shrink by no more than 3 mm depth.

The viscosity of the raw material mixture to be foamed, measured with a commercial mixing viscometer, must be at least 500 cP. At this viscosity, it passes the above-mentioned casting test each time. The upper viscosity limit for the mixture to be foamed is about 12,000 cP. It may be exceeded if the sample passes the pencil test.

According to the second test procedure, the lower limit of viscosity is determined so that the raw material mixture does not drain completely from a Ford cup with an outlet of 4 mm.

Mixtures of raw materials that do not pass the pencil test give unstable foams whose pore volume fraction can no longer be reproduced well enough. In this case, the decomposition of hydrogen peroxide, even when using catalysts, is incomplete.

The amounts of cellulose ethers and / or proteins according to the invention are between 0.005 and 0.15% by weight, based on the sum of magnesium oxide (burnt magnesite), magnesium chloride and water. The quality and molecular size of the cellulose ether have only a minor effect on the stiffening performance of the magnesium cement mixture. The use of methyl hydroxyethyl cellulose, 6 6541 6 gelatin and / or glue has proved to be particularly advantageous.

The dosage of clay-like, inorganic thickeners is determined by the plasticity of these substances and the desired effect. When using plastic contact binders, which are used, for example, in the manufacture of enamelling slurries, a proportion of 5 to 10% by weight, based on the total weight of the raw material mixture, is generally sufficient. When less plastic kaolin is used, about 5-25% by weight is required.

The density of the liquid mixture to be foamed is controlled by the amount of hydrogen peroxide added. This amount is between 0.25 and 1.5 g / cm 2.

The decomposition of hydrogen peroxide begins about 30 seconds after its addition to the feedstock and ends after about 30 minutes.

When preparing porous shaped bodies from the magnesium cement according to the invention, it is possible to add the individual components to the mixture successively, on the other hand, for example, a wetting agent and / or cellulose ethers and / or soluble proteins can be dissolved or suspended in water beforehand.

According to the invention, the foamed magnesia cement mixtures solidify into porous shaped bodies with valuable properties. Thus, the porous magnesium cements form excellent fire protection layers. Furthermore, by means of the masses of these pores, fire doors with a fire resistance time of about 1 hour per 1 cm of layer thickness can be produced per magnesium-cement foam produced according to the invention. In particular, porous magnesium cements reinforced as an additive with glass fibers of a length of about 3 to 30 cm combine good fire resistance and high mechanical strength at a low bulk density of about 0.5 g / cm 3. Instead of or in addition to glass fibers, for example, iron oxides, inorganic dyes and anti-corrosion agents such as sodium nitrite, potassium nitrite or alkali phosphates can be used as additives.

From the pulp presented above, heat-insulating building elements with a low bulk density and a high mechanical strength can be produced in a particularly simple manner, for example by applying to molds. Thanks to the high flow limit of the foamed mass, they can be handled on site without the use of complex protective boards. Of particular note in this context is the application of fire protection masonry to cable ditches without the use of lining.

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It has been found that foamed magnesium cements with a high flow limit are very well suited for coating fillers whose specific gravity differs very strongly from the specific gravity of the foam. They can thus be reinforced, for example, with ground short glass fibers as an additive, thereby preventing, for example, cracking in a fire for the most part.

Surprisingly, the shredded glass fiber bundles further mixed into the non-foamed mixture can be very easily broken down into individual fibers without changing the length of these fibers. Furthermore, pulps mixed with glass wool can be easily foamed without the glass fibers forming agglomerates.

The porous solids obtained in this way have a very high flexural strength. In contrast, ground short glass fibers do not significantly alter the mechanical strength values of the porous bodies.

Similar reinforcement is also obtained with other inorganic or organic fibers, for example basalt fibers, kaolin wool, glass wool and / or cut organic textile fibers as additives.

Usually, it is not possible to cover porous fillers with a low bulk density and a substantially closed pore structure with a mass having a substantially higher bulk density, because the light filler rises upwards in the liquid binder and enriches on the upper surface under the action of hydrostatic lifting force. Surprisingly, it has been found that the foamed compositions according to the invention do not suffer from this disadvantage. Namely, it is sufficient to disperse the light porous filler in the raw material mixture and then foam it without separation. Even if organic substances are used as porous additives in these cases, the prepared solids are not flammable and have a very good sound absorption capacity.

Further suitable additives for the mixtures according to the invention are from the group of closed porous organic fillers, for example foamed granules of polystyrene having a grain size of 2-3 mm and a bulk weight of about 30-50 g / l. Preferred inorganic porous additives having a closed pore structure include: hollow glass beads, granulated foam glass, foamed perlite, aerated concrete and the like.

According to one procedure, porous bodies having particularly advantageous properties are obtained if a glass 6541 6 fibers as well as porous additives having a closed pore structure are mixed with a magnesium ascinctise composition having the above composition, and this mixture is then foamed with hydrogen peroxide.

The invention is further illustrated by the following examples.

Example 1

In a 4-liter mixing vessel equipped with a planetary stirrer at 100 rpm, the following ingredients were added and mixed into a homogeneous mixture: 648 g of a 33% magnesium chloride solution 600 g of calcined magnesite 20 g of milled fiber 90 g of water 1 g of water 1 g of water (sodium alkyl sulfonate) 0.5 g of manganese chloride (MnCl2.4H2O)

If desired, the wetting agent and manganese chloride were each dissolved in a portion of the water to be added. A mixture of 20 g of hydrogen peroxide, 35% and 15 g of water was added to the homogeneous mixture with stirring.

After the addition of the hydrogen peroxide solution, oxygen evolution began within a few seconds, which after about 10 minutes had ceased. The foamed, easily flowable cement mixture was castable after gasification and completely drained from the mold with a 2 mm wide gap. The mixture had a viscosity of 120 cP and a runoff time of 26 seconds from a Ford cup with an opening of 4 mm. After maintaining its final volume, the foam had a viscosity of 3200 cP.

Example 2 (comparative example)

The procedure of Example 1 was followed, however, 160 g of ground limestone with a grain size of less than 0.065 mm was added to the raw material mixture with stirring. After reaching the final volume, the foamed mass was still freely castable and flowed completely freely out of the mold with a gap of 2 mm. The viscosity of the mixture was 115 cP and the pour-out time from a Ford cup with an opening of 4 mm was 29 s. After flotation, the viscosity of the pulp was 3200 cP.

Example 3 (comparative example)

The procedure was as in Example 1, except that an additional 0.5 g of methylhydroxyethylcellulose dissolved in the raw material mixture was further mixed. This cellulose ether having a viscosity of 10,000 cPT in a 2% solution of 9,65416 was pre-dissolved in a portion of the water to be added to the mixture as a 1% solution.

The mixture had a viscosity of 390 cP and a discharge time of 113 s from a Ford cup with an opening of 4 mm. After flotation, the viscosity of the pulp was 6000 cP.

Prior to foaming, the viscosity of the raw material mixture did not differ from the viscosity of the mixture shown in Example 2. Although the mass was clearly more difficult to flow after flotation than the mass according to Example 2, it was completely flowable and did not have a noticeable flow limit.

Increasing the amount of cellulose ether added had virtually no detectable effect on the viscosity or flow limit in the foamed mixture.

The foams prepared according to Examples 1-3 cured into porous solids, indicating the stability of the foam structure corresponding to the easily flowable nature of these foams.

Example 4

In a 4-liter mixing vessel equipped with a rotary planetary stirrer at 100 rpm, the following raw materials were mixed together into a homogeneous mixture: 648 g of a 33% magnesium chloride solution 600 g of calcined magnesite 30 g of milled fiber 1 g of wetting agent (sodium 0.5 g manganese chloride (MnCl2.4H2O) 0.3 g methylhydroxyethylcellulose 90 g water.

Finely ground, slurried kaolin was mixed into this homogeneous mixture until a groove about 1 cm deep, drawn on the blunt end of a pencil, completely disappeared into this mixture in 10 seconds. This required 170 g of white kaolin.

After homogeneous stirring of this kaolin, the mixture was foamed by stirring a solution containing 20 g of 35% hydrogen peroxide and 15 g of water. Oxygen evolution began a few seconds after the addition of hydrogen peroxide and was complete after 10 minutes. A foamed mass having a porous structure with a bulk density of 0.5 g / cm was formed. This foam was so difficult to drain that it did not drain out of the container by self-vibration. However, it could be taken into a masonry bucket and filled into a mold without changing the foam structure. The pencil-drawn groove as described above remained virtually unchanged in this foam.

The mixture had a viscosity of 820 cP and no longer completely drained from a Ford cup with a 4 mm orifice.

The viscosity of the foamed pulp was 10,000 cP.

The mass obtained according to Example 4 solidified into a porous solid body with a density of 0.5 g / cm, corresponding exactly to the density of the foam. Its compressive strength after 8 days was 33 kp / cm 2 and its flexural strength 13 kp / cm.

Example 5

In a mixing vessel according to Example 4, the following raw materials were mixed together into a homogeneous mixture: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 250 g of calcined magnesite 250 g of kaolin 0.5 g of methylhydroxyethylcellulose 0.5 g of manganese chloride 1 g of sodium alkyl sulfonate 100 g of

This mixture was foamed by stirring a solution containing 12 g of a 35% hydrogen peroxide solution and 20 g of water. A foamy mass was formed which, after evolution of oxygen, was so difficult to flow that it did not drain out of the mixing vessel, even by vigorous vibration. After curing, a porous solid body with a density of 0.7 g / cm 3, a flexural tensile strength of 20 kp / cm and a compressive strength of 55 kp / cm 2 was formed after 8 days of storage.

The viscosity of the mixture was 11,500 cP. The groove drawn on the blunt end of the pencil disappeared within 10 seconds.

The viscosity of the foam was 15,000 cP.

Example 6

In the mixing vessel of Example 4, the following raw materials were mixed into a homogeneous mixture: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 155 g of kaolin 0.5 g of methylhydroxyethylcellulose 0.5 g of manganese chloride 100 g of water.

11 6541 6 40 g of chopped strands with a length of 6 mm were dispersed in this mixture, whereby the bundles of glass fibers were divided into individual fibers.

The mixture was foamed with a solution of 20 g of 33% hydrogen peroxide and 20 g of water.

The resulting foam could only be applied to the mold with a spatula. Within 12 hours, the foam had cured to a porous solid having the following properties: density 0.55 g / cm 2, flexural strength 30 kp / cm 2 and compressive strength 43 kp / cm 2.

Example 7

In the mixing vessel of Example 4, the following raw materials were mixed into a homogeneous mixture: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 155 g of ground kaolin 0.5 g of methyl hydroxyethylcellulose 0.25 g of menganium chloride 0.1 g of tetramethylammonium perfluorooctane sulfonate

The homogeneous mixture was foamed by stirring 20 g of 33% hydrogen peroxide diluted with 20 g of water. Ten minutes after the addition of hydrogen peroxide, a foamy, difficult-to-flow mass formed which did not drain out of the mixing vessel, even with vigorous vibration. The mass was applied with a spatula to the mold. After storage with a change in weight of less than 1% by weight, the properties of the porous solid were as follows: bulk density 0.5 g / cm 2 flexural strength 15 kp / cm 2 after 8 days compressive strength 45 kp / cm after 8 days

Example 8

In the mixing vessel of Example 4, the following raw materials were mixed into a homogeneous mixture: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 70 g of binder contact clay 0.5 g of methylhydroxyethyl Li se L Luioosa 12 6541 6 0.25 g of manganese chloride 1 g of sodium alkyl sulphonate .

This mixture was foamed with a solution of 20 g of 35% hydrogen peroxide and 20 g of water.

The foamed mass was difficult to drain so that it could only be removed from the mixing vessel by vibrating very vigorously. The groove drawn into the foamed mass on the blunt end of the pencil remained sharp-edged without flattening. The viscosity of the mixture was 3700 cP and the foam made therefrom 15,000 cP.

The mass solidified into a porous solid having a bulk density of 0.4 g / cm 2 and a compressive strength of 33 kp / cm 2. The bond contact clay was a fatty, iron-poor clay commonly used as an excipient in the manufacture of enamel slurry.

Example 9

In a mixing vessel, a raw material mixture having the following composition was prepared: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 150 g of white clay 0.25 g of manganese chloride 0.5 g of cellulose ether 1.0 g of sodium alkyl sulfonate 100 g of water.

This mixture was foamed using 20 g of 35% hydrogen peroxide and 20 g of water.

The foamed mass was so difficult to drain that it could not be cast even with intense agitation. It was applied with a spatula to a pretreated mold and the ae cured to a porous solid

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into a body with a bulk density of 0.5 g / cm.

The viscosity of the raw material mixture was 1100 cP both without cellulose ether and after its addition. After reaching the final volume, i.e. after about 5 minutes, the viscosity of the foamed mass was 5000 cP.

White binder clay was a commercial product commonly used to make enamel slurry. In this case it was a medium-fat kaolin-containing clay.

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Example 10

In a mixing vessel according to Example 4, a raw material mixture having the following composition was mixed into a homogeneous mixture: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 150 g of kaolin 0.25 g of manganese chloride 0.5 g of an organic thickener 100 g of water.

The organic thickener was dissolved in a portion of water to a 1% solution before addition. The following organic thickeners were used: carboxymethylcellulose methylcellulose methylhydroxyethylcellulose gelatin bead adhesive sodium caseinate.

The homogeneous mixture was foamed after the addition of the organic thickener with a solution of 20 g of 35% hydrogen peroxide and 20 g of water.

All foams containing the aforementioned organic thickeners were difficult to flow, structural viscous and could not be poured freely but only with a masonry bucket.

In contrast, foamed mixtures prepared by adding polyvinyl alcohol, starch, dextrin, alginic acid, tragacanth, gum arabic, or sodium water glass were free-flowing and could be poured from a mixing vessel. They also flowed through a 1 mm wide gap without difficulty.

Example 11

A homogeneous mixture of the following raw materials was prepared: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 100 g of ground kaolin 0.5 g of cellulose ether 0.25 g of manganese chloride 0.5 g of sodium alkyl sulfonate 130 g of water.

14 6541 6 These were foamed by mixing a solution of 12 g of 35% hydrogen peroxide and 20 g of water in the mixture. A rigid porous mass was formed in which the groove drawn on the blunt end of the pencil remained permanent. Granulated, porous polystyrene was mixed into this foamy mass with a grain size of about 3 mm. It was possible to add without difficulty by mixing 50 g of polystyrene spheres without changing the foam structure of the refractory mass. Upon curing, it formed a solid with a bulk density of 0.4 g / cm 3. Without the addition of 2 polystyrene spheres, a bulk density of 0.7 g / cm would have been expected. The porous solid was very well suited as a liner material for sound attenuation.

Example 12

The foamed pulp of Example 11 was prepared. After foaming, 500 g of hollow glass balls with an average diameter of 10 mm were mixed into this mass. In this case, it was necessary to replace the basket mixer with a simple, single-arm mixer, because hollow glass balls that required a very large amount of space would otherwise have blocked the mixer. The volume weight of the resulting mixture after curing was 0.66 g / cm 2. The bulk weight of the hollow glass spheres was 350 g / l.

Example 13

A homogeneous mixture of the following raw materials was prepared: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 50 g of ground kaolin 0.5 g of cellulose ether 0.25 g of manganese chloride 0.5 g of sodium alkyl sulfonate 30 g of ground short glass fibers 100 g of water.

An additional 150 g of finely divided iron III oxide obtained by annealing technical iron II sulfate was added to the mixture.

This mass was foamed with a solution containing 30 g of hydrogen peroxide (35%) and 30 g of water. A foamed mass was obtained which was so rigid that it could be cut into cubic pieces with a masonry trowel. This mass could be applied with a spatula to the molds without dispersing its foam structure. The hardening residue had a bulk density of 0.33 g / cm 3 and a compressive strength of 10 kp / cm.

Example 14

A homogeneous mixture of the following raw materials was prepared: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 100 g of ground kaolin 0.5 g of cellulose ether 0.25 g of manganese chloride 0.5 g of sodium alkyl sulfonate 30 g of ground short glass fibers 100 g of water.

This mixture was foamed by stirring a solution of 10 g of 33% hydrogen peroxide and 10 g of water. Despite the relatively small proportion of pore volume, the foamed mass was not free-flowing and could not be applied to the moistened brick wall in a layer at least 10 mm thick in the vertical areas. After curing, the bulk density of the pulp was 0.74 g / cm.

Example 15

A homogeneous mixture was prepared from the following raw materials: 650 g of a 33% magnesium chloride solution 600 g of calcined magnesite 155 g of ground kaolin 0.5 g of methylhydroxyethylcellulose 0.25 g of manganese chloride 1 g of sodium alkyl sulfonate .120 g of water.

To this mixture was mixed 20 g of a crystalline addition compound of hydrogen peroxide and urea corresponding to the formula (NH 2) 2 CO. H 2 O 2. Oxygen evolution began immediately. The foamed pulp was identical to the pulp prepared by adding an equivalent amount of 35% aqueous hydrogen peroxide. It cured to a porous solid body with a pore size of less than 1 mm.