EP0570413A1

EP0570413A1 - Fire extinguishing and protection agent.

Info

Publication number: EP0570413A1
Application number: EP92903639A
Authority: EP
Inventors: Juergen Buil; Gernot Loehnert
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-02-05
Filing date: 1992-02-04
Publication date: 1993-11-24
Anticipated expiration: 2012-02-04
Also published as: DE59205254D1; EP0570413B1; CA2101947A1; AU1184392A; ATE133573T1; WO1992013602A1; DE4290321D2

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

Fire extinguishing and fire protection agents

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

A well-known disadvantage of water as an extinguishing agent is its thin liquid, which makes it large during the extinguishing process

Flows away unused 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 the 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, e.g. water-soluble inorganic salts or water-insoluble minerals such as bentonite or attapulgite. (See "Ullmanns Encyclopedia of Technical Chemistry", 4th ed., Vol. 11, p. 569 and Ullmanns Encyclopedia of Industrial Chemistry, 5th ed. Vol. A 11, p. 114/115)

In special cases, such as fighting forest fires, for example, bentonite, attapulgite and water-soluble salts and also alginates contain extinguishing water preparations which, after special preparation, are often thrown off from aircraft. (Literature e.g. C.E. 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). %), of corrosive effects of certain salts such as sulfates or chlorides or the possibility of undesired environmental influences occurring, for example of fertilizer-active components, the quantity application of which can be several times per area when extinguishing a forest fire than when applying fertilizer in agriculture. The preparation of such thickened special extinguishing agents usually requires special equipment, especially for their mixture. They are usually also not usable with ordinary fire extinguishing syringes, as in the case of alginate gums, for example, by no means have optimal adhesion to surfaces after spraying, especially when exposed to heat, often change their application properties after a short period of storage and sometimes leave them difficult to remove after drying Residues.

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 also have 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 LÖBch process maintained and, if necessary, can also be quickly and easily produced by adding ordinary water and 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-Othmer's 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 pyrogenic silica is only described as a powdery special extinguishing agent for special fire situations (EUR 0339 162 AI or EUR 0311 006 AI). 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). However, this "thickening effect" is due to its slowness and its small size for the this task is insignificant. This process, even if it can be accelerated somewhat by adding electrolytes, does not offer a solution for the task at hand. Such suspensions, thickened by leaving them to stand, 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-fighting syringes, since they adversely affect adhesion in this way thickened water severely affected.

As shown, e.g. 4% slurry of pyrogenic silica in water, even after thickening due to storage when spraying, again thin.

The object is therefore 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, broadly contractual minerals in the form of their slurry in water to thicken, which is instantaneous and controllable, gives a defined and durable final state and is not thixotropized by the spraying process so that its adhesive effect 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 problem it was found that the preparation of a thickened slurry of amorphous synthetic

Silicic acid in water by adding powdered pyrogenic silicic acid with water and a compound of the type of a polyethylene glycol with a molecular weight> 700 - <600,000, derivatives of polyethylene glycol such as its ethers with fatty alcohols, its esters with fatty acids, ethers with carbohydrates of the molecular weights of 300 or larger and with polyethyleneimine is possible. 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.

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, one obtains a thickened extinguishing water which can be used at the moment and 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 extinguishing water thickened in this way improve its spraying properties, for example its throwing distance or the lower frictional losses, in comparison 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 as a fire extinguishing agent described here is particularly effective, since large areas can be covered with the highly efficient extinguishing agent in a very short time using a normal extinguishing device, regardless of the material it is made of or the geometric position exhibit. When exposed to heat, this coating shows no decay, such as softening or slipping until the water dries up.

The water thickened as described has a number of essential advantages, such as good sprayability or sprayability by means of various 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 handheld fire extinguishers Adhesion of even thick layers of extinguishing agent of several centimeters in thickness up 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 substrates, e.g. by hosing down with water or by vacuuming with a standard industrial vacuum cleaner. Because most of it thickened

Extinguishing water is not lost due to running, it can be taken up again after the extinguishing process and thus contamination of the environment is limited by fire products which may run off with the extinguishing water or water damage to buildings become. After drying out, the remaining silica gel has adsorbing properties, which can also be advantageous, for example, for absorbing decomposition products from the firing process or other impurities. It is particularly advantageous to utilize 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 customary extinguishing devices, but which can be used as fire protection compositions, since they maintain their homogeneity even with a high water content and low silica content. In contrast, a silica gel obtained from water glass by neutralization and washing or by ion exchange and set in paste form is only shortly after

Production homogeneous, and soon begins to secrete water in considerable quantities. 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 the preventive fire protection of combustible

Structures, in fire-retardant barrier elements or cable trays, especially those that are sensitive to corrosion, to fire decomposition products or to water flowing out.

The "thickening additives" used according to the invention are required in all cases only in extremely low weight concentrations. With preferably used proportions of only 0.003-0.256 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 or bentonite of above 1% in water by the compounds mentioned of the polyethylene glycols or oxyethylated fatty acid, fatty alcohol or sugar derivatives or of polyethyleneimine abruptly with even the smallest proportions by weight of the same Thickening can be brought about, that the thickening effect obtained can be stored almost indefinitely, so that the extinguishing agents obtained in this way can be stored or used in stationary extinguishing devices, or that the shear effects which occur during the extinguishing process do not act in the form of thixotropy, but on the contrary generate a kind of "irreversible rheopexy", 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 above these values overall of the polyether type to slurries which have already thickened causes their permanent 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 manageability, 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 thickened 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 carried out without difficulty with sea water, 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 determined in the strongly acidic area with polyethyleneimine. 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 thickening effect described is particularly pronounced with pyrogenic silica. As shown in the examples, the concentrations required for precipitated silicas to achieve a significant thickening are significantly higher (5-15%) and the adhesion effect is less good.

Precipitated silicas, on the other hand, are cheaper than pyrogenic silicas.

An inexpensive basis could also be the silica sols, for example made from water glass by neutralization, if a homogeneously thickened slurry could be produced therefrom without great expenditure of time and process. Although such silica sols, if they are not stabilized, tend to gel, that is to say to form a coherent gel these jellies are unsuitable for the task at hand here because their adhesion to surfaces is poor and they excrete the water they contain over time and gradually harden them. In general, their particles cannot be shifted against each other even when they are formed, which means that there are no flow properties. By dispersing such silica jellies, however, suitable thickened aqueous silica slurries can be partially prepared for the fire-fighting task presented here. It is also possible to leave the relatively low salt content in the extinguishing agent in the case of a usable thickening after the neutralization process, which does not impair the extinguishing effect. However, these thickened slurries of synthetic, amorphous silica produced by neutralization processes do not behave rheopex like those made from pyrogenic silica. They are suitable for situations in which the quick, uncomplicated preparation on site or the direct production in the fire extinguishing process is not as crucial as the filling of fire extinguishers or stationary extinguishing systems.

It has also been found in the solution to the problem of providing an effective and versatile fire extinguishing agent based on a thickened extinguishing water that, similarly to synthetic amorphous silica, the mineral bentonite also starts from one low-viscosity slurry in water of only a low concentration can be quickly and durably converted into sprayable and adhesive thickened slurries. This effect, which occurs immediately with vigorous stirring, is not as strong as with pyrogenic silica. With the thickening additives described in this invention, the slurry can only produce thin slurries in low concentrations

_* Bentonite already in concentrations of 1.5% in water in as

Extinguishing agents useful thickened slurries are transferred to water, and show good adhesion to surfaces. In contrast, the same effect with the known thickeners such as gums, polyacrylamide, polyoxyethylenes of molecular weights> 600,000 or at least gelatin in the low concentrations of bentonite described here.

In the context of this invention, the stabilization of the fire extinguishing agents described was also advantageous

Frost effects were determined by adding compounds of the glycol or glycerol type. 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 suspended in 190-196 ml of water while 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, only if there are still light ones

Lumps can take up to 14 seconds to flow out. 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 are added to these suspensions PEG-120 jojoba acid and PEG-120 jojoba alcohol (mainly eicosenyl or docosenylic acid / alcohol from jojoba oil, ethoxylated), or a 20% polyethylene 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 varies 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 for the polyoxyethylene compounds of about 1.5% in the total mixture above which re-liquefaction occurs. If the thickened slurries of silicic acid obtained in this way, 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 atomizing 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 changing due to spreading, slipping or any other way of causing fire extinguishing. 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 with a molecular weight of 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 formed . 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 a viscosity 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 silica (97 g) and polyoxyethylene lauryl ether (3 g) obtained according to this example is poured into a storage vessel and placed over a suction hose, which is fed into a running water stream via a pipe connection, by means of a light Vacuum sucked into this water flow, whereupon mixing and thickening occur, so that the water emerging just a few centimeters after the mixing point from a slightly narrowed glass nozzle 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 intake feeds, regulating the water quantity 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, pp. 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 (comparative example)

The thickened silicic acid 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 (comparative example)

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 is retained in all polyoxyethylene compounds in these acidic areas. In contrast, re-liquefaction is observed for those mixed with polyethyleneimine.

Example 6 (preparation and use 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 produced in this way proved to be sprayable with a multi-purpose jet pipe "D" according to DIN 14365, part 1. During the spraying process, there was a clear 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 1 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 also established. Even after standing for 14 months while avoiding evaporation losses, the material was not found to settle, and it was easy to spray afterwards.

Example 7 (production and application with a load-bearing syringe)

10 kg of pyrogenic silica were stirred into 190 l of water. The resulting slurry contained easily crushable particles with a diameter of 2-3 mm, which slowly sedimented to the bottom when left standing. The supernatant suspension no longer has any particles and shows properties of a cloudy silica sol which, after standing for 6 weeks, still contains 3% silica (determined gravimetrically after drying and annealing). 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. A part was kept locked 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 easily sprayed with a TS 2/5 portable fire pump according to DIN 14410 with a multi-purpose spray lance "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 Experiment 7, further dilution with water is possible if required, while maintaining the properties.

After use, the thickened, sprayed extinguishing water could be taken up again by shoveling or suctioning off, so that any secondary 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. Here, there was practically no change in its usage behavior, nor did residues settle on the bottom of the vessels. It was also not possible to detect any obvious bacterial contamination 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 quenched with thickened extinguishing water, prepared according to Example 7, adjusted to 2.5 and 3% SiO 2 content, with a spray jet. 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 re-ignitions 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. At the star ken 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 ground. The agent is suitable for extinguishing flammable materials such as wood, plastic, rubber, wood-based materials, textiles and other organic solid materials.

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 described thickening additives 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 approx. 3% 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 sol is exposed to a shear effect in a blender for 5 minutes. 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

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

A slurry which had been diluted 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 comparative extinguishing agent, and the number of re-ignitions compared to water was reduced to half. The

The effect is significantly better than that of 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 that of 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 for 48 hours in the refrigerator at -12'C, where B is viscous and A syrupy appeared viscous. After thawing, the thickening obtained after adding the thickener remained as before freezing.

Example 15

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. After the addition of potassium bicarbonate, a similar result is observed, with up to 34% being able to be dissolved in the slurry due to the higher solubility. The outlet viscosity in the DIN cup here is 35 seconds. The pH of these mixtures is 8.6. It is also found that sprayed-on layers remain moist for 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 approx. 8 mm, the dimensions approx. 10 x 10 cm. Cable pieces 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 provided with a

Insert made of a plastic itter. 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 an 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. Example 21

5 g of bentonite (Korthix H-NF or GK 129-H, trademark from Amberger Kaolinwerke, Amberg Germany, or bentonite DAB 9) were suspended in 200 ml of water with an electric stir bar. 0.7 g of a 20% strength solution of polyethyleneimine in water were added to this low-viscosity suspension with a viscosity of 11 seconds in a DIN beaker (4 mm) and the mixture was stirred with a stirring rod. The run-out time in the 4mm cup according to DIN was 14-15 seconds afterwards, the spraying and adhesion behavior was good. When heating the splashed

Areas showed no liability problems. A lot of water vapor was formed.

Example 22 As example 21, but using 3 g of bentonite. The run-down time was 13 seconds, the spray behavior was good, the adhesion behavior on cold surfaces was satisfactory, and good on hot surfaces.

Example 23 (comparative example)

As in Example 21, but with the addition of 20 ml of a mixture of 1 g of guar gum in 100 ml of water. There is only a slight thickening effect, and a clear aqueous phase separates at the bottom of the beaker. Guar gum alone does not act as a thickener at these low concentrations of bentonite.

Claims

Expectations

Claim 1

Production and use of a fire extinguishing and fire protection agent from thickened water, characterized by the production of a thickened slurry of amorphous, synthetic silica in water with a weight content of silica of at least 1%, preferably 2-9%, with adhesive effect on surfaces and structures

Claim 2

Production and use of a fire extinguishing and fire protection agent from thickened water, characterized by the production of a thickened slurry of amorphous, synthetic silica or bentonite in water with a weight content of silica or bentonite of at least 1%, preferably 2-9% and addition of 0.003 to 1.5, preferably 0.007 to 0.5 percent by weight, based on the total amount of the fire extinguishing agent, of polyethylene glycols / polyoxyethylene of the molecular weights from> 700 to <600,000 or of derivatives of the

Polyethylene glycol / polyoxyethylenes such as polyoxyethylene fatty alcohol ethers, polyoxyethylene fatty acid esters and their mixtures and polyoxyethylene sugar alcohol fatty acid esters with a molecular weight of 300 or greater or of polyethyleneimines as thickeners.

Claim 3

Production and use of a fire extinguishing and fire protection means from thickened water, according to claims 1-2, characterized by increasing the thickening and the adhesive effect of the thickened aqueous slurry of amorphous, synthetic silica by the spraying process with conventional fire extinguishing devices , or by intensive stirring or mixing process. Claim 4

Production and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-3, characterized in that it can additionally contain carbon-forming substances

Claim 5

Production and use of a fire extinguishing and fire protection means from thickened water, according to claims 1-2 and 4, characterized in that it additionally improves the extinguishing effect, e.g. Contains hydrogen carbonates, borates or ammonium phosphates

Claim 6 Production and use of a fire extinguishing and fire protection means from thickened water, according to claims 1-5, characterized by the use of the thickened aqueous slurry of amorphous synthetic silica or bentonite as a fire extinguishing agent with customary fire extinguishers

Claim 7

Production and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-6, characterized in that it can be deposited as a supply of extinguishing agent on the flammable or endangered object by the adhesive effect, and thus reduces the risk of fire spreading and prolong the extinguishing effect of the water by avoiding draining

Claim 8

Production and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-7, characterized by the possibility of absorption after the end of the extinguishing process to avoid contamination Claim 9

Production and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-8, characterized in that it remains even after drying of the water due to the remaining, adhering to the object, small quantities of silica or bentonite residues due to their non-combustible has a fire-reducing effect, as well as absorbing harmful fire by-products through its absorbing effect

Claim 10

Production and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-9, characterized in that it is without damage to the loaded objects, e.g. can be removed by spraying with water

Claim 11

Production and use of a fire extinguishing and fire protection agent from thickened water, according to claims 1-10, characterized by its use in stationary fire extinguishing systems, fire blankets and throwing aids

Claim 12 Manufacture and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-5, characterized in that it is applied in suitable coverings, for example in the form of flexible pillows on the areas to be protected [Received at the International Bureau on July 20, 1992 (July 20, 1992); original claims 2 and 4 amended; all further

Claims unchanged (2 pages)]

Claim 1

Production and use of a fire extinguishing and fire protection means from thickened water, characterized by the production of a thickened slurry of amorphous, synthetic silica in water with a weight content of silica of at least 1%, preferably 2-9%, with adhesive effect on surfaces and structures

Claim 2

Production and use of a fire extinguishing and fire protection agent from thickened water, characterized by the production of a thickened slurry of amorphous, synthetic silica or bentonite in water with a weight content of silica or bentonite of at least 1%, preferably 2-9% and addition of 0.003 up to 1.5, preferably 0.007 to 0.5 percent by weight, based on the total amount of the fire extinguishing agent, of polyethylene glycols or polypropylene glycols with a molecular weight of> 700 to <600,000 or of derivatives of polyethylene glycol or polypropylene glycols such as polyoxyethylene fatty alcohol ethers, polyoxyethylene fatty acid esters and their mixtures and polyoxyethylene sugar alcohol - fatty acid esters with a molecular weight of 250 or greater or of polyethyleneimines as thickeners.

Claim 3

Production and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-3, characterized in that it can additionally contain carbon-forming substances and / or foaming agents

Claim 5

Claim 7

Claim 8

Production and use of a Feuerlösch- and Brandschutz¬ means of thickened water, according to claims 1-7, characterized by the possibility of absorption after the end of the extinguishing process to avoid contamination