FOAM-COMPATIBLE MIXTURE FOR FIRE FIGHTING

The invention concerns a foam-compatible mixture for fire fighting. It is well-known that the surface properties can be modified by solids, by applying ein$ilan or a Siloxan, which polymerizes frequently, whereby a layer from Polysiloxan or silicone on the surface develops. By such a treatment a generally hydrophilic surface becomes hydrophob. If this is applied ßehandlung to the individual particles by powder, the flow characteristics of the powders themselves become or of other pulverfömigen solids, to the soft treated particles added, were improved. However thereby different characteristics can be impaired seriously, for example characteristics, which depend on the presence on hydrophilic groups at the surface or on the attraction on other hydrophilic groups at the surface. To the Veramchaulichung it is pointed out that most well-known treatments of silicic acid with silane and Siloxan make the surface in such a manner hydrophob that the silicic acid causes a collapsing of most aqueous foams. So now found that for most purposes, from which the Sehaumverträglichkeit represents an example a purify-hasty silicic acid is needed, which characteristics exhibits, which is appropriate for the untreated and the hydrophoben silicic acid between those. The invention concerns from there a foam-compatible mixture for fire fighting, which is characterized by that it has a powdered silicon dioxide, a surface of at least 10 m2/g and a Hydrophobizitätsgrad within the range of 5 to 3fi, measured by determination of the minimum percentage share methanol in a liquid mixture consisting of methanol and water, soft miscibility of 0,2 g of the powdered Silieinmdioxyds with 50 to! 00 cma the liquid mixture effectuation, exhibits, and a dry powdered feueriöschendes means contains. Preferably silicon dioxide is in the mixture in a concentration of, 5 to 30 Gew. - %, in particular 12 to 20 Gew. - % contain. As feueriöschendes means preferably eir alkali metal salt, in particular a connection of the general formula MC N 03, becomes 2,9 in soft M for sodium or potassium stands and yields the reaction product of urine, often and Natriumoder potassium carbonate or - bicarbonat represents, used. The Hydrophobizitätsgrad is measured by the methanol titration test; this is an empirical test, which differentiates between and identifies powdered silicic acids from each other, which exhibit a degree at Hydrophobizität, for which between that one the untreated Kieselsäum with a hydrophilic surface and that one is appropriate the treated Kieselsänre, whose surface was made ollständig ₜ hydrophob. The “Methanoltitratioutest” for the determination of the degree of the Hydrophobizität of a treated silicon dioxide is accomplished as follows: 0.2 g to 50 cm3 wet powdered-rehearses into a conical piston with 250 cms contents is given. A US of a burette is titrated methanol, while the mixture in the piston is constantly agitated. At first the surface of the silicon dioxide powder remains; if however more methanol is gradually always in addition-given, then one sees that something silicon dioxide of the surface of the Pulverhäufchens crumbles and that-mainmixes in the liquid remains suspended. This indicates that the terminator point is close and that the Geschein must be reduced ndigkeit that methanol addition. The “terminator point” of titration is reached, if the entire silicon dioxide of the surface of the Pulverhäufchens crumbled and the powder is completely dispersed in that methanol/water mixture in form of a suspension. The degree is derHydrophobizität indicated as that percentage share methanol, which is present in the Flüssigkeitsmisehung consisting of methanol and water, if that terminator point of titration is reached. It is well-known that Silanolgruppen on surface untreated silicic acid available are, and it assumed that the replacement of Silanolgmppen changes the character of the surface of hydrophilic by groups, which exhibit a hydrocarbon final's group, for example a Alkyloder Phenylgruppe, after hydrophob. However it is not necessary to withdraw all Silanolgruppen in order to remove the entire hydrophilic character effectively. It is possible that the groups, which lend the hydrophoben character, cover the surface in such a manner and perhaps cover the Silanolgruppen that the hydrophilic character of the surface lost goes and the silicic acid as it were hydrophob becomes “complete”. This Erscheinnng is defined in such a way that those purify-hasty silicic acids result in a value over 40 in the case of methanol titration. The silicic acids with that hydrophoben moderately a character, which were selected for the mixture according to invention, since they exhibit a favorable equilibrium of the characteristics, give with the methanol test worth between 5 and 3fi. If the use of Kieselsäurepulvem with a value from 15 to 35 is preferred with this Test.Es was observed that these letz, eren with a multiplicity from A described later nwendungsz hits a corner to prefer is. For the optimal equilibrium between good flow characteristics and a good foam compatibility, for example with fire fighting foams, a silicic acid with values of to 30 is particularly preferred with the same test. Hydrophilic purify-hasty silicic acid, which is sometimes called “largeupper-laminar” or “colloidal” flint-sour, can be manufactured after a multiplicity of methods, for example by pyrogene methods or through losses and drying dispetgießen silicic acid brines. The surface range can amount to for example 10 to q0 m2/g, lies however generally within the range from 100 to 400 m /g, whereby the respective certain surface range (or turned around the size of the selected particles) is selected depending upon the intended intended purpose. Everyone the hydrophilic Kieselsäuten described above is suitable in the mixture according to invention to be used. However the use becomes “smoke” - silicic acid with small Schüttgewicht, which was manufactured by thermal decomposition of silicon halides, prefers. The degree of the Hydrophobizitat, which is necessary during the mixture according to invention, can be lent to the silicic acid by a multiplicity of methods, for example by chemical treatment of the surface with a silane, a Siloxan, or mixtures of silanes and Siloxanen. These methods of the chemical treatment can be adapted in such a manner that the desired degree at Hydrophobizität on at least three ways will receive. 1. Groups of methyls are small and show a high degree at Hyd ophobizität, it can however less hydrophobe groups of hydrocarbons to the surface chemically be bound, for example ethyl, Phenylund Alkoxymethyl. 2. The surface coverage of the hydrophoben groups can be limited either (A) by use of a small concentration the reagent, which is insufficient, in order to react with all Silanolgruppen on the surface, or (B) by use of a hydrophoben group, so that steirische factors that-load from sufficient nGruppen prevent. The first method (A) is with difficulty reproducible, and second is a half theoretical attempt, which be probably used can if certain groups, z.Bo Trimethyl more silyloder tertiary Butyl silylgruppen, to be added. 3. Between the hydrophoben groups intentionally hydrophilic groups can be switched on, for example Alkoxygmppen or Polyäthergmppen, by chemical connection of such groups to the Kieselsäumoberfläche over the entire silicic acid surface. This can be accomplished, as either both hydrophilic and hydrophobe groups are introduced to some Organosiliciumverbindung oderindem the Kieselsäum reacted with two-connections, which are in such a manner constituted that they bind both groups separately. A preferential method for a such treatment of the surface consists of that powdered Kieselsänre with essentially water-free monomers a silane of the general Pormel (R) n SI -- (L) “- n' where n = 1, 2 or 3 and R is a hydrophobe group, which avenges opposite the Silanolgruppen on the surface is reactive, and L a group is, which is reactive opposite the Silanolgmppen on the silicic acid surface, chemically is converted. The group of L can cover a Nlederalkoxygruppe, a Chloroder bromine atom or an acyl group. The Niederalkoxygruppe is generally a group with up to five carbon atoms and can either a primary or a secondary alkoxy group be or one alkyl ether represent, which is replaced with a Oxygmppe, e.g. CH OCHzCH O. it is sometimes favourable, two or three different groups shown by L zurVerfügnng u to have, since generally secondary is less reactive opposite Alkoxygmppen the Silanolgruppe on the surface than primary alkoxy groups, to remain more along-easily intact and is so capable to lend to the surface a hydrophilic character after the Silanmolektüe with its hydrophoben groups of R became to vedmnden. The particularly preferred group of L is the Äthoxygmppe, and it was observed that a particularly geeigneres silane a connection R-- SI (OC2 Hs, where R a group is indicated as in the following, it represents. The group of R can be a group of hydrocarbons or a substituted Kohlenwasserstoffgmppe, whereby the substitution takes place via in atom or a group, which stably and in relation to the silicic acid is inert, for example chlorine, Phor, tri fluorine methyl, Alkyloder A will be more ryläther, the group of hydrocarbons generally eineAlkyloder group of one alkenyls with i to 20 carbon atoms, for example a phenyl, a benzyle, a Tolyl, Cyclopentyloder group of cyclohexyls. In the connections, in which n equal to I is not, the group of R can be same or different and one of these groups can an alkyl ether connection contain or it can the whole group a Polyalkylenäthergruppe be. If a group of (R) n is a rather large group, i.e. a group, which contains more than 4 carbon atoms, then is preferred that the other groups (R) are n small groups, for example Methyloder groups of ethyls. Silanes, only one group of R (i.e. if contain n = 1), in particular, if the other group is a Alkoxygmppe, for example Phenyltrichlorsilan, n-Propyltrichlorsilan, Methyltriäthoxysilan, langkettiges Alkyltriäthoxysilan are particularly preferred, of which the Methy! - is most easily usable triäthoxysilan. When alternative to crude description connections can be used a silane, which exhibits a hydrophilic substituent for either a Roder a L-group. The hydrophilic substituent is to zwe& a most moderate niehüonische Polyätherkette, for example a PL oxide chain. Certain ones reactive silanes (for example Dimethyldichlor ilan) are more difficult to use than others them to easily a Käeselsäure with a surface supply there, which is in higher measure hydrophob, than for the mixture according to invention one wishes. The adjustment of the reaction for the achievement of the exactly wished equilibrium between a hydrophobem and hydrophilic character of the surface is obtained most easily with for example tri methyl chlorosilane, and this is preferred to the Dimethyldichlorsilan from there with the production of the mixture according to invention. It is to be accepted that the Trimethylsilylgruppe, which is a voluminöse group permits probably no broad coverage of the surface with hydrophilic groups. From there the kind and size of the GrupFen, which are present in the silane, should be drawn naturally together with the Oberfläehenbereich of the silicic acid, in calculation, if the concentration of the silane, which reacts with the silicic acid, is determined. In order to ensure that at least a substantial portion of the silane does not polymerize before its reaction with the surface it is essentially held, the silane for drying, until it comes with the surface of the silicic acid into contact. After the surface had been treated with the silane, the chemical reaction between the silane and the surface can be begünsügt by water and/or or by warmth. Traces of water are nearly always present at a KieselsäureoberfIäche, and it can be present in the silicic acid sufficient water, in order to favour the reaction with the silane. So a silicic acid with a large surface up to 8 Ge can; - % water (however 0, 5 to 1, 5a/0 is desired) contain, since this water concentration favours the reaction the monomers of the silane with the silicic acid particles in appropriate ant. It can be necessary to reduce the Peuchtigkeitsgehalt of the silicic acid for example by drying during approximately 1 h at a temperature of 80 bis70°C. Then the silane can be added to the KieS0 selsäure and mixed intimately, and, if the chemical reaction is slow, it is appropriately, the treated silicic acid, if necessary in a slow nitrogen stream to preferably warm up to a temperature from 40 to 100°C, 88 to 70°C. Warming up is preferably accomplished under an aqueous atmosphere, for example in a closed container or in a furnace, by which regular quantities steam are through-led. If reactive connections like (CH) SiC1 or [(CHs) s SI] 20 to be used, it is not so necessary to warm up the silicic acid. The concentrations at silane or Siloxan, preferred for the treatment of the largeupper-laminar silicic acid, at least 1 Ge t amounts to. - %, for example 1 to 80 Gew. - % silane, which is added to the silicic acid, however preferably 10bis 20%, if a Alkoxysilan is used, and fi to 15%, if a chlorosilane is used. The increase of the weight can be limited by the degree of the coverage of the surface, whereby ster sees/factors is probably more substantial than the total concentration of the existing silane. A eating action of a kieselsäurehalügen surface as descriptive above, lends a hydrophoben character in certain measure to the surface, however it is accepted that it these not completely hydraulic - phoh makes. By silanes different silicon connections can be used and supplied for reaction with the Silanolgruppen on the Kie48 selsäureoberfläche according to invention the products suitable for the use in the mixture. To split up symmetrical Siloxane and Silazane are particularly suitably, probably because they exhibit the inclination, itself in two or more identical reactive groups (- sirs), which a Siliciumatom contain, and groups to the silicic acid in a way are in such a way bound, which is similar to the reaction with monomers silanes of the general formula R SiL. For example the connections Hexamethyldisiloxan, Hexamethyldisilazan, sym Dtvinyltetramethyldisiloxan can be used in appropriate way, in order to supply silicic acid with intermediate Hydrophobizitat. Is difficult, Siloxanpolymere with a silicic acid for production fttt the reef according to invention mixture desired Hydrophohizität umzuset cn. They react easily with Kieseisäure, however this has a large inclination to become in higher measure hydrophob than for the mixture according to invention one gewttnscht. However a Polysiloxan, which contains hydrophilic groups as substituent at the Siliciumatom, can be appropriately used. The hydmphflen groups, which cover for example Oxyalkylengmppen or groups of hydroxyalkyls, adjust the hydrophoben character of the Polysiloxankette, and according to invention a silicic acid suitable for the mixture is won. So a suitable can do Polysiloxan one generally, ne formula (CH) s SI [OSi (CHs) 2] [Oh--SI (CHs)] OSi (CHs) s n] m (OCHzCH2) z OCHs exhibit, and by appropriate choice of the values for n, m and z a coat on a powdered silicic acid with a Hydrophobizität can be won, which is wished for according to invention the Silieinmdioxyd suitable for the application in the mixture. Sometimes Polysiloxane are manufactured by a reaction between Alkyloder aryl chlorosilanes in present of water. The used silanes is generally mixtures of mono, Dlund Trichlo - silanes of of the general formula (R SI (CI) x, where R is a Alkyloder group of aryls and x for 1, 2 or 8 stands. Different chain lengths or bypass degrees can be manufactured by change of the relative portions of mono, Diund tri chlorosilanes. If the portion of the tri chlorosilane is high, then it is pointed out that a considerable bypass can be introduced, and if a concentration at mono chlorosilane is present, which is not sufficient, around all bypass ends with a SiRs Gmppe to mistake at the bypass ends by the hydrolysis of a Si-C1-Gmppe hydrophilic Silanolgmppen is in such a way formed. A mixture of chlorosilanes, as described above, can be used for the treatment by powdered silicic acid, and if the portion of Triehlorsilan is high, a partie11 hydrophobe silicic acid is formed, which is suitable for the use in the mixture according to invention. The constituent amount of the silanes can be for example: Mono (, R SiCl) - 2% to 5% Di (R2 SiC12) - 65% to 82% trichloroethylene (RSiCls) - 15% to 30% you can be given alsDampfgemfsch to the powdered silicic acid, and the reaction effected at the surface the part, hen, since generally sufficient water is present; however further water can be added if required. A mixture of silanes as above described, in which R for CHs stands, preferred. Hydrophobe silicic acid finds widespread application prevented as Pließzusatzstoff for powder, an additive, more softly bonding together with the storage, which distance from the storage vessel relieved and flowing the powder facilitates also later. The partie11 hydrophobe silicic acid described here is suitable for this Verwendnngszwecke in the concentration range from 0,1 to 5%, preferably 0, 5 to 2, 5%, since she lowers the inclination of the hydrophoben form to cause a collapsing of the foam to a minimum. So the silicic acid with advantage, suitable for the erfindnngsgemäße mixture, can be used as flow additive to fire fighting powders, in order to make it compatible with foam, eineßigenschaft, yields for a fire fighting powder is very erwüuseht, so that after the rapid Plammenlöschwirkung of the dry powder a foam cover can be formed. Powders and purifying hasty plague materials generally can be treated in favorable way with partial hydrophober silicic acid as free-flowing means or as A ntibackmittel, and it is particularly favorable, if it is added to a powdered solid, which is to come with the use into contact with more wässer/towards system or in more wässer/towards system is used. The invention becomes by the following examples, to which it is however not limited, more near er48 läutert: B e ispiel 1:20 of parts of Triäthoxymethylsilan are sprayed on 100 parts “smoke” - of a silicic acid, which exhibits a surface of 200 m2/g and contains 2% water. The silane and the silicic acid are thoroughly mixed in a locked cone mixer 2 h at room temperature. Mixing is continued with an O temperature of 60 C further 24 h, on which the Miseher is opened against the atmosphere. The mixture is getroeknet 6 h in the same equipment, as the mixing process 6 h is continued with open departure, in order to make for formed ethanol possible an escaping. B e is pi el 2:30 of parts of Triäthoxymethylsilan are sprayed on 100 parts silicic acid with a surface of 200 mZ/g and mixed at room temperature thoroughly. The mixture is spread in open bowls, which are in a furnace with 60°C, whereby by the furnace steam is led, in order a constant humidity to keep upright. The reaction is continued 12 h. The Dampfzufuhr is then broken off and the mixture in the same furnace for a further period is dried by 6 h. B eispiel 3: A laboratory test for the foam compatibility is used, in order to judge the treatments accomplished at the silicic acid. lg the treating silicic acid or 20 g of a dry fire-extinguishing powder, which contains 1.5% silicic acid, with 30 cms gasoline in a small beaker is mixed. The mixing into a paste with we DIN a 2-Liter-Meßzylinder poured, and 5 cms additional gasoline are used for washing the beaker. As! 0 Blindprobe is poured 25 cm3 gasoline into another 2-Liter-Meßzylinder. Both Meßzylinder are weighed. The two cylinders become Sehaumfeuerlö with a protein foam from gefü! as per (the foam is to exhibit a Expansionsverhältnis between 7 and 8). A stop watch is switched on, if the cylinders are gefttllt. The two cylinders are measured again weighed uud the half Entw ssemngszeit both by the sample and by the Blindprobe. The values 1/2 drainage time of the sample of! 00 x 1/2 drainage time of the Blindprobe can be computed in such a way (% F.C.). The test becomes also on 20 g of oath of dry fire-extinguishing powder, that! g silicic acid as additive contains, applied. The results, which to receive became by the foam compatibility test for different treated silicic acids and for 1,59o of the same of treated silicic acids, which were added to a fire-extinguishing powder, which after in the example the 1 brit. Patent specification No. 1.168.092 descriptive procedures was manufactured, becomes in table! stated. Table I for the treatment of the silicic acid used silane desert, silicone Meth] ltriäthoxysilan Methyltriäthoxysilan nPropyltrichlomilan Tris-3chloräthoxymethyl Phenyl trichlorsilan Hexamethylsiloxan EP5904 (approx. langkettiges A lkyltriäthoxysilan) tri methyl chlorosilane treated silicic acid alone 63 68 76 57 values of %F.C. 54 Brandbekämpfuugspulver, which 1.5% silicic acid contain 62 68 62 samples of dry chemical powder, which result in results, which are larger than 50 f (lr the % the F.C. - Values, are generally satisfying in the U.S. Underwriters test for fire-fighting chemicals. Silicic acid, which with Methyttriäthoxysilan (as in table 1) one treated, to a fire-extinguishing powder, which consists of Natriumbiearbonat, one in addition-gives, and % F become. C. - values from over 50 receive, which lie typically within the range of 60 to 80. B ice pi el 4: A “Raueh” - silicic acid is treated with a Silieiumverbindung in accordance with table 2 during one period from 48 to 72 h at room temperature, and afterwards to the completion of the reaction of a thermal treatment at a temperature within the range 50 to 70°C ven subjected. With the resulting silicic acid a methanol titration test was accomplished for the determination of the Hydrophobizität, and it was observed that according to the used portion of the silicon connection and the length that response time, which fall for the Hydrophobizitätsgrad of received values into certain ranges in accordance with table 2. Table 2 silicon connection Methylvinyldichl orsilan Phenyl triahlorsilan trichloroethylene methyl chlorosilane Dimethyldiäthoxysila n n-Propyl-trichlorsilan Hexamethyldisiloxan Diphenyldichlorsilan Methyltääthoxysilan C 14 - A Ikyl triäthoxysilan degrees of the Hydrophobizätät (measured by the MethaholTitratäous test) 3444! 5 - - 42 - 42 25B e i s pi e I 5: 15 parts of Triäthoxymethylsilan are sprayed on 100 parts “smoke” - silicic acid, which are contained in an india rubber mixer heated up. The temperature of the Kiesesläure during spraying amounts to 50 to 55OC.Die “Rauch' silicic acid has a specific surface of 200 mz/g and contains 1% humidity. Mixing is continued 2 h with 50 to 55°C. Then the temperature 12 h is increased to 65 bis70°C. During this period a slow nitrogen stream is blown over the surface, in order to remove ethanol resulting as by-product, and the nitrogen stream is strengthened during the last 2stflndigen drying period. B ice piel 6: 25 parts of Triäthoxymethylsilan become more tiber 100 parts “smoke” - silicic acid (surface I0 200 mz/g) sprayed. The Kieselsäum and the silane are thoroughly mixed in Dreikegelml 24 h with ambient temperature. The treating silicic acid is spread in open bowls with a depth by 36 mm. This is placed into a furnace, kept softer 65°C, and through soft steam one through-leads, so that the atmosphere remains damp. The reaction is continued 12 h. Steam is then turned off and the silicic acid in the same furnace further 2 h is dried. The analysis of the concentration of the Äthoxygruppen on the silicic acid results in values between I, 1 and 1,4 for the relationship of Äthoxy: Total carbon, whereby the average value betftlgt 1.25. The value 1.25 indicates. that the middle molar ratio from Äthoxygruppen to Methylgmppen on the silicic acid I: I amounts to.