EP0570413B1 - Fire extinguishing and protection agent - Google Patents

Abstract

Production and use of thickened sludges of synthetic amorphous silicic acid or bentonite in water as a fire extinguishing and protection agent in which the water is mixed with preferably 1 to 7 % wt. synthetic amorphous silicic acid and the resultant thin fluid suspension is rapidly thickened by the addition of a small proportion of polyethylene glycols of molar mass of 700 or more or of polyoxyethylene fatty alcohol ethers, fatty acid esters, polyoxyethylene sucrose alcohol fatty acid esters or polyethylene imine, or said substances are premixed and then intensively mixed with water so that the aforementioned percentage weights are attained, or the aforementioned minor additives are dissolved in water in suitable quantities and the silicic acid is added in solid form. The use of this thickened water preparation can, for instance be used as a fire extinguishing agent in ordinary extinguishers or in the form of fire protection cushions, for instance, to prevent fire propagation.

Description

As an extinguishing agent, water has the advantages of high heat absorption capacity and thus a favorable cooling effect, non-existent toxicity, compatibility with many flammable substances, good value for money and usually good availability. It is therefore still very important as a fire extinguishing agent.

A known disadvantage of water as an extinguishing agent is its thin liquid, through which large quantities flow unused during the extinguishing process and sometimes cause unnecessary water damage. This means that only a small part of the sprayed water can exert its beneficial extinguishing effect, which consists in cooling the fire material. There have therefore been many attempts to improve water as a fire extinguishing agent.

For example, the addition of substances that increase its viscosity, such as cellulose derivatives, alginates or water-soluble synthetic polymers such as polyacrylamide, is described. Incombustible mineral additives to the extinguishing water are also used, for example water-soluble inorganic salts or water-insoluble minerals such as bentonite or attapulgite. (See "Ullmanns Enzyklopadie der Technischen Chemie", 4th ed., Vol. 11, p. 569 and Ullmanns Encyclopedia of Industrial Chemistry, 5th edition vol. A 11, pp. 114/115)
In special cases, such as fighting forest fires, extinguishing water preparations containing for example bentonite, attapulgite and water-soluble salts as well as alginates are used, which after special preparation are often thrown off from aircraft. (Literature, for example, CE Hardy, Chemicals for Forest Fire Fighting, 3rd. Ed., Boston 1977) However, because of various disadvantages other than forest fire fighting, such extinguishing agents have practically no significance as generally applicable fire extinguishing agents.
The reasons for this are, for example, the generally high proportions by weight of the mineral additives required to achieve a sufficiently high thickening (e.g. 10-20% by weight), due to the corrosive effects of certain salts such as sulfates or chlorides or the possibility of undesirable environmental influences, e.g. fertilizing components, the quantity of which can be several times per area when extinguishing a forest fire than when applying fertilizers in agriculture. The preparation of such thickened special extinguishing agents usually requires special equipment, especially for their mixture. They are also usually not usable with ordinary fire extinguishing syringes, as in the case of alginate gums, for example, do not have optimal adhesion to surfaces after spraying, especially when exposed to heat, often change their application properties after a short storage period and sometimes leave residues that are difficult to remove after drying.
The provision of a thickened extinguishing water without these disadvantages, in particular an incombustible thickener for water to improve the extinguishing effect of the water, is therefore very desirable. In addition to the positive effects of adhesion to surfaces, it should retain its application properties even after long storage, even at elevated temperatures, the formation of coherent extinguishing agent films with the highest possible water content and sufficient resistance, chemical and physiological compatibility with all dead and living materials that occur during the extinguishing process if necessary, it can also be quickly and easily manufactured by adding ordinary water and can be used with commonly available fire extinguishers. An efficient fire extinguishing agent that meets all of these requirements does not currently exist.

Some of the required properties, such as broad compatibility with living and dead matter, are fulfilled, for example, by amorphous silica, which is why it is not only widely used as a thickener (lit. in Ullmann's Encyclopedia of Technical Chemistry, 4th ed., Vol. 22 , P. 473, Kirk-Othmers Encyclopedia of Chemical Technology, vol. 20, p. 778; H. Brünner, D. Schutte, Chemiker Ztg. 89, (1965) pp. 437-40; H. Fratzscher, Farbe und Lack 75 (1969) pp. 531-8).

It shows a pronounced thickening effect in particular in the form of the pyrogenic silica produced by flame hydrolysis in non-polar liquids. In polar liquids such as water, the thickening effect of this silica is less pronounced, so that relatively large amounts have to be added for a practically important thickening effect. So far it is not known that silicas in the form of aqueous slurries have found use as such as fire extinguishing agents. The fumed silica is only described as a powdery special extinguishing agent for special fire situations (EP-A-0339 162 and EP-A-0311 006). Due to the property of their extreme lightness, their general use as an extinguishing agent is not practical.

For example, if you slurry pyrogenic silica in water, you need significantly more than 10% to obtain a practically usable thickening, which slurry behaves thixotropically. This is a disadvantage for use with the usual fire extinguishers. If you e.g. A 5% suspension of pyrogenic silica sprayed in water from different spraying devices always results in thin liquids emerging from the nozzles, which run out on surfaces similar to the water. In the extinguishing comparison test on standardized fires, such undickened silica slurries do not behave better than water.

It is also known that suspensions of amorphous synthetic silicas in water tend to agglomerate particles and sedimentation over time (usually over weeks or months), but this "thickening effect" is due to its slowness and its small size for the task at hand insignificant. This process, even if it can be accelerated somewhat by adding electrolytes, does not offer a solution to the task at hand. Such suspensions, thickened by standing, become thin again by stirring even after a longer storage period, that is to say that this thixotropic liquefaction is also disadvantageous when spraying in the conventional fire extinguishing syringes, since it adversely affects the adhesion in this way thickened water severely affected.
As shown, a 4% slurry of pyrogenic silica in water, for example, becomes thin again even after thickening due to storage during spraying.

It is therefore an object to provide an improved fire extinguishing agent of the type of a thickened extinguishing water, in particular with a small amount by weight of synthetic amorphous silica or other, non-combustible, widely compatible minerals in the form of their slurry in water to achieve a thickening which is instantaneous and controllable runs, gives a defined and durable final state and is not so thixotropic by the spraying process that its adhesion is impaired. Furthermore, it should be easy to use with conventional fire extinguishers and require no special facilities for its preparation, and should have good adhesive properties even on vertical or downward-facing surfaces, especially at elevated temperatures. Above all, however, their extinguishing effect should be clearly superior to that of water.

To solve this task, it was found that a thickened slurry of amorphous synthetic silica in water with a silica content of at least 1% to at most 9% with the addition of 0.003 to 1.5% by weight of an additive, based on the total amount of the fire extinguishing agent _, of polyethylene glycols and / or polyoxyethylene of molecular weights from> 700 to <600,000 or of derivatives of polyethylene glycol or polyoxyethylene such as polyoxyethylene fatty alcohol ethers, polyoxyethylene fatty acid esters and their mixtures and polyoxyethylene sugar alcohol fatty acid esters of molecular weights of 300 or greater or of polyethyleneimines as thickeners, the thickening and fire action being caused by the injection device or can be reinforced by intensive stirring or mixing process. The required silica concentrations in water are only very low, they are only a fraction of the proportions otherwise required for thickening in aqueous slurry, namely 1-7% compared to> 10% otherwise. Preferably 2-7% by weight of amorphous silica and 0.007 to 0.5% by weight of the additive are used.

The additives mentioned can be added to the low-viscosity slurry of silica in water, but can also be premixed dry with the water itself, but also with the silica. In In any case, a compressed extinguishing water that can be used at the moment is obtained, which is thickened significantly in a controlled manner, for example by the shear effect present in a fire extinguishing pump, without the spraying performance suffering as a result. On the contrary, the flow properties of the thickened extinguishing water improve its spraying properties, for example its throwing distance or the lower frictional losses, compared to ordinary water.

The last process could be described as rheopexy. Since the additional thickening obtained here is not lost again after the shear effect has ceased, one could speak of an "irreversible rheopexy". As a result, the use of the thickened slurry of amorphous synthetic silica described here is particularly effective as a fire extinguishing agent, since large areas can be covered with the highly efficient extinguishing agent in a very short time with a normal extinguishing device, regardless of the material it is made of or the geometric position. When exposed to heat, this coating shows no decay, such as softening or slipping until the water dries up.
The thickened water as described has a number of essential advantages, such as good sprayability or sprayability by means of different types of fire extinguishing syringes according to DIN (bucket sprayer / TS 2/5) also by means of a high pressure pump with a working pressure of 100 bar, applicability from hand-held fire extinguishers, liability Even thick layers of extinguishing agent from several centimeters thick to evaporation or drying, even on vertical and downward-facing surfaces of different materials and properties. After the fire-fighting measures have been completed, the extinguishing agent can be removed easily and without damaging the respective subsurface, for example by spraying with water or by suction using a conventional industrial vacuum cleaner. Since most of the thickened extinguishing water is not lost through running, it can be taken up again after the extinguishing process, thus limiting contamination of the environment by fire products that may run off with the extinguishing water or water damage to buildings will. After drying, the remaining silica gel has adsorbing properties, which can also be advantageous, for example, for absorbing decomposition products from the fire process or other contaminants.
It is particularly advantageous to use this property of the fire extinguishing agent according to the invention by sucking in the dry premix of the amorphous silica with the thickener into a stream of extinguishing water, the desired thickening currently occurring. It is noteworthy that an addition of little more than 1%, for example pyrogenic silica, into the water is sufficient for this.

Higher amounts of silica in water can also be advantageous for certain applications, for example to create a barrier with the extinguishing agent against the uncontrolled drainage of liquids from the fire area or to use the absorbing effect of the silica for any existing pollutants. Above 7% of silicic acid in water, pastes which can no longer be applied form with the conventional extinguishers, but which can be used as fire protection compositions, since they maintain their homogeneity even with a high water content and low silica content. By contrast, a silica gel obtained from water glass by neutralization and washing or by ion exchange and set in paste form is homogeneous only shortly after production and soon begins to separate out a considerable amount of water. The fire protection composition produced according to the invention avoids this phenomenon with a high water and low solids content. These fire protection compounds are versatile for preventive fire protection of flammable structures, in fire-retardant barrier elements or cable trays, especially those that are sensitive to corrosion, fire decomposition products or water that flows out.

The "thickening additives" used according to the invention are only required in extremely low weight concentrations in all cases. With preferably used proportions of only 0.007-0.5% by weight based on the total amount, they almost do not fall more weight. Various of the thickening additives described are usually used as emulsifiers, for example for fats, waxes or as special surfactants. The "flocculation" of silica with polyglycol is considered useful, for example, for water clarification. From the previous teaching it cannot be concluded that a slurry of silicic acid of above 1% in water can be brought to a uniform thickening abruptly with even the smallest parts by weight of the above-mentioned compounds of the polyethylene glycols or ethoxylated fatty acid, fatty alcohol or sugar derivatives or of polyethyleneimine that the thickening effect obtained can be stored almost indefinitely, so that the extinguishing agents obtained can be stored or used in stationary extinguishing systems, or that the shear effects that occur during extinguishing processes do not have the effect of thixotropy, but on the contrary a kind of "irreversible rheopexification" generate, which extremely promotes use as an extinguishing agent by the generation of stably adhering water layers. This is also surprising because the compounds mentioned do not correspond to the type of the usual "thickener".
It is also characteristic of the present invention that the described thickening no longer occurs at concentrations of the thickening additives of the polyether type of above certain limits (> 1.5%) or that the addition of amounts of concentrations of thickening additives of the polyether type which are overall above these values for slurries that have already thickened their immediate permanent dilution. In practice, however, this is not a problem since the addition can be easily controlled.
An increased pH also has a similar effect on the action of the polyether-type thickeners; at pH values above 8.6 a re-liquefaction of already thickened slurries begins, which is also not disadvantageous, because for reasons of handling, extinguishing agents with a pH value as close as possible to the neutral point must be taken into account. Components with a strong alkaline action can be used with the thickened extinguishing agent formulations mentioned the polyoxyethylene derivatives are therefore not added.

An exception to the polyethers as thickening additives are weakly alkaline compounds, such as the bicarbonates. These are compatible with the densified slurries of amorphous synthetic silica in any soluble concentration. Potassium bicarbonate, for example, can be added up to its saturation concentration of approximately 34%. When extinguished, these bicarbonates can decompose and release carbon dioxide, which increases the extinguishing effect. The thickened slurries of amorphous, synthetic silica according to the invention are also compatible with other, not strongly alkaline salts, for example the preparation can also be done with sea water without difficulty, or potassium sulfate, ammonium phosphate or boric acid can be dissolved in the thickened slurry.
While the thickening additive causes polyethyleneimine to have a durable thickening effect in the aqueous silica slurry in all alkaline areas, a re-liquefaction can be observed with polyethyleneimine in the strongly acidic area. Acidic conditions are avoided anyway in order to avoid corrosion. If required, however, a combination of both thickening additives is possible, which can be used to thicken in the acidic and alkaline range.

The stabilization of the described fire extinguishing agents against frost effects by adding compounds of the glycol or glycerol type was also found to be advantageous in the context of this invention. Compounds such as borates that are effective as antifreeze or corrosion protection can also be used, if necessary. It has been found that a considerable addition of these compounds as antifreeze does not impair the thickening effect or the durability of the thickened fire extinguishing agents described.

The following examples illustrate the invention without restricting it:

Example 1 (general preparation example)

4-10 g of pyrogenic silica (Aerosil 200, reg. Trademark. Degussa, Germany) are slurried in 190-196 ml of water with stirring. The resulting suspensions are thin with a pH of around 5. If they are not stirred vigorously, their run-down times in the DIN cup (4 mm nozzle) are 9-11 seconds, and the run-down time can be as long as there are slight clumps 14 seconds. If you stir them with an electric stir bar (approx. 800 rpm), they become even thinner with a flow time of 9 seconds, comparable to the viscosity of the water. A few drops of polyoxyethylene lauryl ether with a molecular weight of approximately 380 or a 50% aqueous solution of polyethylene glycol with a molecular weight of 4220 or a 50% aqueous solution of polyoxyethylene sorbitan monostearate with a molecular weight of approximately 1200 or a concentrated solution of PEG- are added to these suspensions. 120 jojoba acid and PEG-120 jojoba alcohol (mainly eicosenyl or docosenylic acid / alcohol from jojoba oil, ethoxylated), or a 20% polyethyleneimine solution (Polymin SK, reg. WZ. BASF, Ludwigshafen, Germany) and mixed by stirring with a Spatula. In all cases one occurs immediate, clearly recognizable thickening into a homogeneous, viscous slurry, which looks different depending on the silica content. Flow times of 14-> 35 seconds are then obtained, or paste-like consistencies are generated which, although they can no longer be determined in the flow cup, show good sprayability or adhesion. When the required minimum amounts of the additives mentioned are carefully weighed, it is found that 0.007 g (35 ppm) is already effective and that there is an upper limit of approximately 1.5% in the total mixture for the polyoxyethylene compounds above which re-liquefaction occurs. If the concealed slurries of the silica obtained, which can be stored for a long time, are subjected to a brief, vigorous stirring action (for example with an electric stir bar), the thickening increases markedly and is retained in this reinforced form. Spraying of these laboratory approaches is easily possible with a pump spray bottle with or without an atomizer nozzle. On almost all surfaces such as wood, raw or lacquered, plastic, rubber, glass or metal, unproblematic adhesion is possible even in thicker layers, without the layer being adversely affected by divergence, slipping or any other way of extinguishing the fire. This applies in particular to hot surfaces where no slipping can be detected. The sprayed or sprayed surfaces dry within 12-48 hours depending on the layer thickness and environmental conditions. The remaining dry, mostly flaky silica is easily removed mechanically from the surfaces and can be brushed out well, for example, from tissues.

Example 2 (general preparation example)

4-10 g of pyrogenic silica are mixed with 0.3 g of polyoxyethylene lauryl ether or polyethylene glycol of molecular weight 4220, or polyethylene glycol sorbitan monostearic acid ester (molecular weight approx. 1200) or PEG-120 jojoba acid and PEG-120 jojoba alcohol or polyethyleneimine, so that a dry premix is obtained. To do this, pour 200 ml of water all at once and mix with an electric stir bar (blade diameter 3.5 cm, approx. 800 rpm), whereby paste-like consistencies are obtained. When 150 ml of water are added, viscous slurries are obtained with outlet viscosities of 14-30 seconds in a DIN cup (4 mm nozzle). The properties of the thickened silica slurries obtained, which can also be obtained directly by adding the entire 350 ml of water, show no differences from those obtained according to Example 1 in comparable concentrations.
100 g of a dry premix of pyrogenic silicic acid (97 g) and polyoxyethylene lauryl ether (3 g) obtained according to this example is filled into a storage vessel and placed in a storage tube via a suction hose, which has a pipe connection to a running water stream, by means of a slight vacuum into this Water flow sucked in, whereupon mixing and thickening occur, so that the water emerging from a slightly narrowed glass nozzle just a few centimeters after the mixing point already had excellent adhesion to a glass surface. The suction side of a water jet pump can also be used to suck in the dry premix, wherein the suction of the powdery premix can be continued for a long time without problems or blockages. The thickening method can be controlled as desired by appropriately dimensioning the suction feeds, regulating the amount of water and the water pressure. A useful thickening according to this procedure is achieved, for example, with a silica concentration of only 1.3% in water.

Example 3

By adding a gelatin solution (which is already described by Th. Graham, Philos. Trans. (London) 1862, p. 245/6 as a precipitant for silica sol, but in a weight ratio of almost 1: 1), even at low concentrations e.g. 0.1% of the gelatin achieved a thickening of the pyrogenic silica slurry similar to Examples 1 and 2, but these suspensions show microbial contamination which occurs relatively soon.

Example 4

The thickened silica slurries obtained according to Examples 1 and 2 were each mixed with 5% by weight of sodium carbonate and borax, so that pH values of 11 or were obtained from 9.1. While the thickening in all polyoxyethylene derivatives disappeared immediately after the addition, it was permanently retained in the silica slurries thickened with polyethyleneimine.

Example 5

The thickened silica slurries obtained according to Examples 1 and 2 were each mixed with small amounts of hydrochloric acid until pH 1 was reached and with 2% citric acid or ascorbic acid until pH 2 and 3 were reached. The thickening remains with all polyoxyethylene compounds in these acidic areas. Reliquefaction, however, is observed with those mixed with polyethyleneimine.

Example 6 (production and application with a bucket syringe)

586 g of pyrogenic silica were stirred with 11.68 liters of water. After standing for one hour with occasional stirring, a viscosity of 13 seconds was measured in the discharge cup according to DIN. 35 g of polyoxyethylene lauryl ether were added to this thin suspension with stirring. After a short time, the viscosity of this mixture increased to a pasty, easily stirrable and pourable consistency.

10 liters of this thickened extinguishing water were filled into a bucket syringe according to DIN 14405. The thickened extinguishing water thus produced proved to be sprayable with a multi-purpose jet pipe "D" according to DIN 14365, part 1. During the spraying process, there was a significant further thickening of the material emerging from the jet pipe compared to the material filled into the bucket syringe. The adhesion of the sprayed material on a vertical painted concrete surface (building wall) was very good. After the spraying of approx. 5 l, the remaining approx. 5 l remaining in the bucket syringe were mixed with the same amount of water, mixed by swirling and the spraying process was continued. Even with the resulting reduction in the concentration of the thickened silica slurry, good adhesion to the wall was still noticeable when spraying. In further spray tests with it good adhesion to cardboard, wood and glass was found. Even after standing for 14 months while avoiding loss of evaporation, no material was found to settle, and it was easy to spray afterwards.

Example 7 (Manufacture and Use with a Portable Syringe)

10 kg of pyrogenic silica were stirred into 190 l of water. The resulting slurry contained easily crushable particles 2-3 mm in diameter, which slowly sedimented to the bottom when left to stand. The supernatant suspension has particles no more, and exhibits properties of a turbid silica sol _which% after 6 weeks of standing for 3 contains silica (determined gravimetrically after drying and calcination). The viscosity of the sedimented silica sol is 9 seconds in the discharge cup according to DIN after the 6-week storage, on the other hand 11 seconds directly after the preparation, ie with the particles still in suspension. Both samples of the clarified by settling and of the sol still containing suspended matter could be converted into a thickened silica slurry with all the additives mentioned in Example 1 in the concentrations mentioned there. The still unthickened slurry was stirred with a paddle stirrer, and the 200 liters produced were separated into 2 equal parts. One part was kept closed without further additions to observe the long-term behavior. In the course of a period of 12 months, a slow thickening and settling on the floor occurs when this silica slurry not containing the additives mentioned is left to stand. However, it can be mixed again and sprayed through nozzles, and thixotropy makes it thin again. It can be thickened by the additives mentioned in Example 1 and converted into a thickened aqueous slurry of silica suitable as an adhering fire extinguishing agent. The other part of the batch was mixed with 250 g of polyoxyethylene lauryl ether immediately after production and stirred with a paddle stirrer, which led to the uniform thickening of the entire silica suspension within about 30 seconds.

The firefighting water thickened in this way was sprayed with a TS 2/5 portable syringe according to DIN 14410 with a multi-purpose jet pipe "C" according to DIN 14365, part 1, both as a full jet and as a spray jet. As in the previous example 7, the further thickening of the extinguishing water by the pumping and spraying process was evident. Good throwing distances and excellent wall adhesion on vertical surfaces were achieved. As in Example 6, further dilution with water is possible if required while maintaining the properties.

The thickened, sprayed extinguishing water could be picked up again after use by scooping or suctioning, so that any fire by-products contained therein did not get into the ground or only to a considerably reduced extent.

Extinguishing water thickened with the addition of the polyoxyethylene lauryl ether from this batch was likewise left to stand for 12 months, like the silica slurry without the addition. There was practically no change in its usage behavior, nor did residues settle on the bottom of the vessels. No obvious bacterial contamination was detectable without preservation measures, although it must be noted that a used sample from an extinguishing attempt which was contaminated by a certain amount of soil was contaminated with the odor after a few weeks. In the case of clean storage, special preservation is obviously not necessary.

Example 8 (fire extinguishing test)

A test fire with solid fuels of fire class A (wooden crib, 40x40 cm, 7 layers, pre-burning time 4 min) was extinguished with a spray jet using thickened extinguishing water, prepared according to Example 7, adjusted to 2.5 and 3% SiO2 content. In comparison to the extinguishing attempt with water, only 1/4 of the amount of extinguishing agent was used for extinguishing and the number of reignitions also decreased to 1/4. The adhesive layer of the thickened extinguishing water delays or prevents the spread of fire and ignition of the parts of the combustible material that have not yet been affected by the fire. On the strong Water vapor formation can be seen that the applied, thickened water is almost completely available for cooling and extinguishing, since it does not drain from the combustible parts and drain into the underground. The agent is suitable for extinguishing flammable materials such as wood, plastic, rubber, wood-based materials, textiles and other organic solid substances.

Example 9 (fire extinguishing test)

A 13-A fire (according to BFS 5423) was extinguished with a 3% thickened silica slurry prepared according to Example 7 extinguishing water preparation. The consumption of the extinguishing agent until it was completely extinguished was only 1.7 kg. This means that only 50 grams of silica have been used to completely extinguish the fire. The amount of firewood used here can naturally contain several times this amount of silica in its ashes.

Example 10 (comparative example)

A low-viscosity slurry of 4% of pyrogenic silica in water without the thickening additives described was used to extinguish a test fire of fire class A (as in example 8). Compared to water alone, the unthickened slurry used only marginally less to achieve the same quenching result. The number of reignitions obtained was comparable to that obtained with water itself. This shows that the good quenching effect found is dependent on the presence of a thickened aqueous slurry of the amorphous, synthetic silica.

Example 11

500 ml of an approximately 3% silica sol are prepared from a sodium water glass solution by treatment with a strongly acidic cation exchanger. The pH of the sol is approximately 5. The sol is exposed to shear for 5 minutes in a blender. There is no visible change. After adding 2 g of a 20% solution of polyethyleneimine in water and briefly blinding, the silica sol immediately thickens without becoming gelatinous and has a viscosity of 20 Seconds in the outlet cup, remains sprayable and adheres to surfaces. After repeated shear in the blender, the viscosity is still 14-15 seconds. So there seems to be a slight thixotropy, but this is not disadvantageous for the spraying.

Example 12 (not according to the invention)

500 ml of an approx. 7% silica sol are produced from a sodium water glass solution by treatment with a strongly acidic cation exchanger. The pH of the sol is approx. 5. The silica sol is left to gel and the resulting gel is stored for two weeks. A 3% slurry in water was then prepared in a blender, which was sprayable and showed good adhesion. Its viscosity is 18 seconds in a DIN cup with a 4 mm nozzle.

Example 13 (not according to the invention)

A slurry adjusted by dilution from an approx. 3% slurry of amorphous silica in water to approx. 2.5% silica content had an outlet viscosity of approx. 14-15 seconds. This slurry was used to extinguish a standardized Class A fire. The amount of extinguishing agent required was 1/3 of that of the water used as the reference extinguishing agent, and the number of flashbacks compared to water was reduced to half. The effect is thus significantly better than with water, but not quite as good as the effect of a thickened silica slurry made from pyrogenic silica according to Example 7 and also adjusted to 2.5% (reduction in the amount of extinguishing agent compared to water to about 1/4, Flashbacks 1/4 of those of the water)

Example 14

A slurry of 8 g Aerosil 200 in 150 ml water was prepared. 80 g of 35 g of propylene glycol (A) and 69 g of 46 g of propylene glycol (B) are added to this. A and B are each thickened by adding 4 drops of polyoxyethylene lauryl ether. Both are kept in the refrigerator at -12 ° C for 48 hours, where B is viscous and A is syrupy appeared viscous. After thawing, the thickening obtained after the addition of the thickener was retained as from the freezing.

Example 15 (not according to the invention)

120 g of a thickened slurry of 3% silica in water according to Example 1 are mixed with 5 g of sodium hydrogen carbonate. The outlet viscosity is obtained in a DIN cup (4 mm) for 20 seconds. This mixture adheres well when sprayed onto hot surfaces. When the water evaporates, there is a strong gas evolution, which is more fine-bubble than the extinguishing agent without sodium hydrogen carbonate. A similar result is found after the addition of potassium bicarbonate, whereby up to 34% can be dissolved in the slurry due to the higher solubility. The outlet viscosity in the DIN cup is 35 seconds. The pH of these mixtures is 8.6. It is also found that sprayed-on layers remain moist longer.

Example 16

6 g of Aerosil 200 are slurried in a solution of 10 g of potassium sulfate in 195 g of water and a few drops of polyoxyethylene lauryl ether are added to the resulting thin suspension and the mixture is stirred. The resulting thickening is expressed in an outlet viscosity of 20 seconds in a DIN cup (4 mm).

For the additions of salts described in Examples 15-16, it should be noted that these mixtures no longer behave rheopex, but do not show such strong thixotropic effects when sheared heavily that the adhesive effect on surfaces would be significantly impaired. However, when spraying on walls, these mixtures show a somewhat stronger drainage.

Example 17

83 g of water are mixed with 7 g of pyrogenic silica and 0.1 g of polyethyleneimine (or the same amount of fatty alcohol polyglycol ether of the MG> 300, fatty acid polyglycol ester of the MG> 300, Polyoxyethylene sorbitan monofatty acid ester, or polyethylene glycol of MW> 700) and mixed by stirring. The resulting paste is filled into a plastic bag. The thickness of the pillow thus produced is approximately 8 mm, the dimensions approximately 10 x 10 cm. Pieces of cable of various diameters are placed on the pillow. A horizontal gap of 3 cm in width is covered with this pillow. The gap is then flamed from below with a gas burner. Temperatures of approx. 700 ° C arise on the underside of the cushion. The cables are intact after flame exposure for approx. 20 min.

Example 18

A pillow as described in Example 17 is made with an insert made of a plastic grid. At the ends of this pillow is provided with Velcro fasteners. The resulting pillow is placed around a polypropylene tube with a diameter of 40 mm according to DIN 19560 and closed with the Velcro like a sleeve. The tubular part protected in this way is flamed from below with a fire generated by gasoline in such a way that the flames sweep past the tube or the sleeve on both sides. After 20 minutes, the pipe shows no damage or softening.

Example 19

A pillow, as described in Example 17, is filled with a paste with the addition of 10 g of sugar dissolved in water. The pillow is hung upright and flamed from the front with a gas burner. A cable behind it is intact after 20 minutes. A breakdown of the pillow, as is the case without the addition of sugar, cannot be observed due to the carbon-forming sugar.

Example 20

10.5 g of a precipitated silica are slurried in 150 ml of water. 0.2 g of polyethyleneimine are added to this thin slurry and stirred well. The slurry thickens and has an outlet viscosity of 18 seconds.

Claims (9)

1. A method for producing a fire extinguishing and fire protection agent of thickened water,
   characterized in that
   a thickened suspension of amorphous synthetic silicic acid in water is produced with a content of at least 1% to at most 9% by weight of silicic acid, with the addition of an additive of 0.003 to 1.5 weight % with reference to the total mass of the fire extinguishing agent, of polyethylene glycols and/or polyoxyethylene of molar masses of > 700 to < 600.000 or of derivatives of polyethylene glycol or polyoxyethylene such as polyoxyethylene fatty alcohol ethers, polyoxyethylene fatty acid esters and their mixtures, as well as polyoxyethylene saccharic alcohol fatty acid esters with molar masses of 300 or more, or of polyethylene imines as a thickening agent, in which arrangement the thickening and adhesive effect can be strengthened by a spraying process with conventional fire extinguishing appliances or by an intensive stirring and mixing process.
2. A method according to claim 1,
   characterized in that 2-7% by weight of amorphous silicic acid and 0.007 to 0.5% by weight of the additive are used.
   
3. A method according to claim 1 or 2,
   characterized in that in addition, substances forming carbon networks are added.
4. A method according to at least one of claims 1 to 3,
   characterized in that in addition substances improving the extinguishing effect such as, for example, hydrocarbonates, borates or ammonium phosphates are added.
5. A fire extinguishing and fire protection agent produced according to at least one of claims 1 to 4.
6. Use of the fire extinguishing and fire protection agent of thickened water according to claim 5,
   characterized in that
   it is used as a fire extinguishing agent with conventional fire extinguishing appliances.
7. Use of the fire extinguishing and fire protection agent of thickened water according to claim 5,
   characterized in that
   it is deposited by its adhesive effect as an extinguishing stock on the combustible or endangered object and that thus the risk of any fire spreading is reduced and the extinguishing action of the water is prolonged by avoiding drainage.
8. Use of the fire extinguishing and fire protection agent of thickened water according to claim 5, characterized in that it is used in stationary fire extinguishing installations, fire extinguishing blankets and covers for escape facilities.
9. Use of the fire extinguishing and fire protection agent of thickened water according to claim 5, characterized in that it is deposited in the form of suitable wraps; for example in the form of flexible pads, to the places to be protected.