WO2016153385A1 - Gel de silice expansé, son procédé d'utilisation et de production - Google Patents

Gel de silice expansé, son procédé d'utilisation et de production Download PDF

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Publication number
WO2016153385A1
WO2016153385A1 PCT/RU2015/000819 RU2015000819W WO2016153385A1 WO 2016153385 A1 WO2016153385 A1 WO 2016153385A1 RU 2015000819 W RU2015000819 W RU 2015000819W WO 2016153385 A1 WO2016153385 A1 WO 2016153385A1
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silica gel
sol
foamed
solution
aqueous solution
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PCT/RU2015/000819
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English (en)
Russian (ru)
Inventor
Иосиф Микаелевич АБДУРАГИМОВ
Александр Валентинович ВИНОГРАДОВ
Владимир Валентинович ВИНОГРАДОВ
Геннадий Николаевич КУПРИН
Денис Сергеевич КУПРИН
Евгений Александрович СЕРЕБРЯКОВ
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Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии"
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Publication of WO2016153385A1 publication Critical patent/WO2016153385A1/fr

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    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D1/00—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/16—Preparation of silica xerogels

Definitions

  • the invention relates to the field of production of a sol-gel by the method of foamed silica gel, which can be used as a fire extinguishing agent for explosion and fire prevention, as well as an insulating and filling material in construction and in other industries.
  • organic additives are added to its composition, which increase the viscosity of water (thickeners) or lower its surface tension (foaming agents) [SU 797707, A 62 D 1/00, 1981], or add inorganic salts - chlorides, carbonates and bicarbonates of alkali metals, clay and other fine substances that increase the fire extinguishing ability of water.
  • 2263525, A62D1 / 00, 10.11.2005] which, to increase efficiency, cheapness and ease of use, contains a quenching composition deposited on granules of refractory porous material with a diameter of 10-50 mm with a working layer 1-5 mm thick.
  • the extinguishing composition contains calcium bicarbonate in an amount of 0.2-0.8 weight. o'clock, liquid glass in an amount of 0.2-0.8 weight. hours and 0.1-0.3 weight. including inhibitory additives.
  • the known composition [DE 10054686, 06/06/2002], containing more than 50% liquid glass, mainly 90-98% with a liquid glass module in the range of 1-4.
  • the effectiveness of this composition is ensured by the ability of liquid glass to form a heat-resistant insulating film on the combustion surface, which prevents the access of oxygen to the combustion surface.
  • the main disadvantage of this composition is its high viscosity, in connection with which this fire extinguishing composition is applied to the combustion surface from aerosol containers using transport gases - nitrogen, carbon dioxide or foaming agents, as well as using other devices.
  • liquid glass As a quenching composition, it is necessary to reduce its viscosity by introducing water into the composition.
  • water glass In relation to water, water glass is a thickener, and in relation to water glass, water is a thinner.
  • the components When melted by fire, the components form a glass film on the surface of a burning object and prevent the access of oxygen.
  • this composition may contain a high molecular weight surfactant in the form of a mixture of polyvinyl alcohol - toluene - water with a surface tension of less than 30 mN / m at the rate of 0.001-0.1 kg of surfactant per cubic meter of water in solution.
  • extinguishing a fire with this composition is carried out according to the following mechanism:
  • the solution heats up under the influence of high temperature and its viscosity decreases, which contributes to a better spreading of the solution on the combustion surface.
  • An increase in the wettability of the combustion surface with a solution and an increase in the degree of dispersion of the jet is achieved by introducing into the composition of a high molecular weight surfactant with a surface tension of less than 3 ° S 3 N / m, for example, based on polyvinyl alcohol, toluene and water in an amount of 0.001-0 , 1 kg / m 3 of water in solution.
  • a liquid glass film formed after evaporation of free water on the combustion surface at a temperature of 120-200 ° C loses molecular water and acquires a solid state.
  • chemically bound water begins to be removed, under the influence of which the crust of liquid glass acquires a pyroplastic state, and the released water vapor, due to a sharp increase in its volume, foams this crust and its volume increases 10-50 times.
  • the density of the foam layer formed on the combustion surface is 30-50 kg / m 3 and this layer blocks the access of air oxygen to the combustion surface.
  • the resulting foam layer is not susceptible to burning, as it is an inorganic substance in its composition - anhydrous alkali metal silicate, has a low coefficient of thermal conductivity (0.03-0.036 W / m K) and prevents the quenched surface from heating up to the ignition temperature due to a sharp decrease in the intensity of exposure heat flow generated by the emission of flame and convective heat from flue gases.
  • the disadvantages of RU 2275951 are the practical impossibility of uniformly spraying and the practical impossibility of providing controlled thermal foaming of the liquid glass solution on the surfaces of burning materials that are almost always uneven and changing during the burning process and, accordingly, the impossibility of obtaining a given thickness of a solid foam of a certain structure, as well as the need for high temperature for thermal foaming, namely the need for a temperature of 120-200 ° C for the evaporation of a mole acous- water and tverdoobraznogo acquisition status and the need for 200-400H temperature for Removal of tverdoobraznogo waterglass chemically bound water, under the action of the crust which becomes waterglass pyroplastic state, and the subsequent intensive discharge of water vapor (boiling) for foaming of the crust.
  • Ceramic foam is known - ceramic with a cellular structure, which is usually made on the basis of highly dispersed mineral powders (for example, AI2O3, MgO, ZrO2) and liquid foams.
  • highly dispersed mineral powders for example, AI2O3, MgO, ZrO2
  • liquid foams When a powder wetted by the liquid phase is introduced into the foam, solid particles are distributed in the foam films and gas bubbles are surrounded by two-phase shells. When drying the resulting foam mass, the liquid phase evaporates and a “solid” foam is formed, which is then fired to harden the solid phase.
  • the average density of foamed ceramics depends on porosity, for example, for foamed ceramics based on A Oz; with a porosity of 30% it is equal to 1200 kg / m 3 , and with a porosity of 85% 600 kg / m 3 .
  • Pence-ceramic which has low thermal conductivity and high heat resistance, is mainly used as a heat-insulating material [http.7 / dic.academic.ru / dic.nsf / bse / 119309 / Ceramic foam].
  • a known method for the production of ceramic foam material based on 5 alumina [RU 2225227, A61 L27 / 00, ⁇ 04 ⁇ 35 / 00, ⁇ 04 ⁇ 38 / 00, Publ. 03/10/2004] by grinding alumina in an aqueous medium, preparing a ceramic suspension, molding on an organic foam or molding with a burnable filler, or molding by foaming a ceramic suspension on an adhesive emulsion, sintering-carbonization in an oxidizing medium at ⁇ 1 150–1250 ° ⁇ and firing in oxidizing medium at 1750-1790 ° C.
  • Ceramic foam material contains at least 98.0 wt.% Alumina, 0.15-0.4 may. % magnesium oxide, not more than 0.1 wt.% silicon oxide and not more than 0.1 wt.% iron oxide, has a melting point of 2040 ° C, the average grain size of corundum is 0.5-15.0 microns.
  • thermal insulation material (up to 1500 ° C) of thermal insulation material [RU 2091348 ⁇ 04 ⁇ 28 / 26, publ. 09/27/1997], including liquid glass, clay raw materials, a foaming agent and water, characterized in that it additionally contains fiberglass, carboxymethyl cellulose in the following ratio, May. %:
  • liquid glass 18-30 clay raw materials 47-57, fiberglass 4-9, foaming agent (aluminum powder) 1-3, carboxymethylcellulose 1-4.5, water 9-19.5.
  • a disadvantage of the known ceramic foam materials is the need for firing a "solid" foam, during which the foaming, usually organic structure burns out, and the mineral structure is hardened by the polymerization of inorganic components.
  • sol-gel processes Eng. Sol-gel process
  • the technology of materials, including nanomaterials including the production of sols followed by its transfer into a gel, that is, into a colloidal system consisting of a liquid dispersion medium enclosed in a spatial network formed connected particles of the dispersed phase.
  • sols Unit gel, from lat. Gelo - “freeze”
  • Gels are structured systems consisting of high molecular weight and low molecular weight substances.
  • sol-gel process (sol-gel technology, sol-gel method) ”unites a group of methods for the preparation (synthesis) of materials from solutions, the essential element of which is gel formation at one of the stages of the process.
  • Concentration of sols followed by gelation is carried out by dialysis, ultrafiltration, electrodialysis, evaporation at relatively low temperatures or extraction. It is known that the processes of solvent removal from the gel (drying) play an extremely important role in the sol-gel process. Depending on the method of their implementation, various synthesis products (xerogels, ambigels, cryogels, aerogels) can be obtained.
  • Airgel is the common name for all gels with a low solids content, the pores of which are filled with air, in a narrower sense they are characterized by the fact that they are used in supercritical drying, in the preparation of cryogels, freeze-drying, and in the preparation of xerogels, convection subcritical drying ,
  • Ambigel is a product of drying an aqueous or organic gel at atmospheric pressure, characterized, in contrast to xerogel, by low density values approaching the density of airgels
  • sol-gel synthesis products are used as precursors in the production of oxide nanopowders, thin films or ceramics.
  • Xerogels with a porosity of more than 60% and a density of less than 0.6 g / cm 3 , as well as supercritical drying aerogels, are characterized by low thermal conductivity due to the high porosity and the fact that nanostructured walls of xerogels conduct heat much worse than conventional materials.
  • composition A including fumed silica and an aqueous acid solution, wherein the molar ratio of H2O / S1O2 in composition A is equal to or less than 20, and its pH is equal to or less than 1.5;
  • composition B including silica and an aqueous solution of a base that does not contain metal cations, the molar ratio of H2O / S1O2 in composition B being from 6 to 40, and its pH being from 10.5 to 13; preparation of mixture B by mixing composition A and composition B in a ratio such that the molar ratio of silica from composition A and silica from composition B is from about 1: 2 to 3: 1, wherein the pH in mixture C is from 1 to 5, and the molar ratio of HgO / SiO g is from about 5 to 15;
  • the disadvantage of this method is the technical complexity and multi-stage implementation, as well as the inability to obtain a macroporous structure, and therefore the material according to RU 2278079 in a dehydrated state is characterized by a relatively high density.
  • a known method of producing a highly porous xerogel by sol-gel technology [RU 2445260 ⁇ 01 ⁇ / 16, publ. 03/20/2012], according to which the synthesis of the initial gel is carried out under the influence of ultrasound in a liquid mixture, which is two mutually insoluble liquid phases, one of
  • This xerogel S1O2 according to RU 2530048 with a characteristic pore size of less than 1 micrometer is obtained by a sol-gel process with subcritical 5 drying of the gel using temporary pore fillers or solid skeletal supports (for example, consisting of carbon or organic substances), which at the end of the preparation process removed by thermal oxidation.
  • temporary pore fillers or solid skeletal supports for example, consisting of carbon or organic substances
  • Auxiliary organic particles, or macromolecules, or carbon particles contained in an inorganic gel prevent the collapse of the inorganic network during the subcritical drying process.
  • Xerogel S1O2 according to RU 2530048 is used as a non-combustible or non-flammable, transparent or translucent or non-transparent heat-insulating material, as a supporting heat-insulating
  • 25 processes, as a mold, as a carrier for sensor molecules in sensor technology, for sound insulation, for humidity control, or as a base material for composite materials.
  • composition for creating foamed aerosol heat-resistant foam based on sodium silicate [EP 0110328], containing two separate solutions, one of which, solution "A”. Is based on an aqueous solution of silicate sodium (50-97%) and propellant (3-50%), and the other - solution "B", which is a hardener.
  • solution “A” the main solution
  • surfactant additives can be added to the “A” solution (to the alkali metal silicates solution).
  • Organic and inorganic compounds having gelling properties preferably carboxylic acid esters, for example triaacetate glycerol, which act as thickeners, act as thickeners, increasing the rheological properties of the foams formed upon mixing according to EP 01 10328, as the “B” (hardener) solution.
  • carboxylic acid esters for example triaacetate glycerol
  • B hardener
  • emulsifiers are also introduced into the solutions, and also stabilizing components are introduced into the solution “B” (hardener), which form microcapsules from salts of polyvalent cations, preferably Zn, Mg, and Ca.
  • the objective of the present invention is to eliminate the disadvantages of the known foamed ceramic materials based on silica and to develop a technically and technologically simple sol-gel method for the production of foamed silica gel at atmospheric pressure, without heating at ambient temperature from -2 to +50 ° C, with a controlled formation rate and hardening from 2 seconds to 2 minutes, with the possibility of its predominant use as a fire extinguishing agent in case of fire and explosion prevention and for other purposes.
  • aqueous solution of silica ash activating ash from alkali metal silicate for example, 0, 1 to 6%, preferably 0.7 to 3.5% aqueous solution of acetic acid, hydrochloric acid or ammonium chloride with a pH from 3 to 8, at the mass ratio of solutions from 100: 1 to 28: 1, mainly 35: 1,
  • a solid ceramic foam material is obtained based on the foamed silica gel, which, while maintaining the foamed structure, has thermal stability when exposed to a temperature of 1000 ° C for up to 40 minutes, which makes it possible to use the obtained foamed silica gel and foam ceramic material based on foamed silica gel as a fire extinguishing agent for explosion and fire prevention, as well as an insulating and filling conductive material in the building and other industries.
  • micro- and macroporous structure has a micro- and macroporous structure with a specific surface area of at least 20 m 2 / g;
  • silica sol solution with a hydrodynamic radius of silica particles of not more than 50 nm obtained from a silica sol solution with a hydrodynamic radius of silica particles of not more than 50 nm by air-mechanical foaming of a silica sol solution during the growth of silica monomers to an average silica sol diameter of 100 nm with a set of mechanical strength in terms of dynamic viscosity from 20 MPa * s to 100 Pa * s in time range from 2 seconds to 2 minutes.
  • the foamed silica gel described above is used as a fire extinguishing agent for fire-explosion prevention and suppression of fires, non-combustible and non-flammable heat-insulating material, as a carrier heat-insulating material, a catalyst carrier, a filter, an absorber, non-combustible or non-flammable light building material, coatings for use in thermal diffusion processes, for ukoizolyatsii for moisture control, or as a base material for composite materials or as an adsorbent for disposal of highly chemicals.
  • foamed silica gel is used as a fire extinguishing agent for fire and explosion prevention and for extinguishing fires of solid combustible materials, for example, lumber, stacks of explosives and ammunition, textile materials, rubber products or plastics, as well as for extinguishing fires of flammable liquids, flammable liquids and flammable liquids in case of emergency spills of oil and oil products or used as a fire extinguishing agent in case of fire and explosion prevention and in extinguishing a fire liquefied petroleum gas, and liquefied natural gas.
  • a foamed silica gel is obtained by air-mechanical foaming of a mixture of an aqueous solution of 5 alkali metal silicate with a foaming surfactant and an aqueous solution of the ash activator silica from alkali metal silicate in the form of an aqueous solution of acetic acid, hydrochloric acid or ammonium chloride.
  • foamed silica gel is prepared by air-mechanical foaming of a mixture of an aqueous solution of sodium silicate with a foaming synthetic hydrocarbon blowing agent and an aqueous solution of acetic acid.
  • Foamed silica gel is obtained from silica sol with a hydrodynamic radius of silica particles of not more than 50 nm with 15 air-mechanical foaming of a solution of silica sol during the growth of silica monomers to an average diameter of silica sol of 100 nm with a set of mechanical strength in terms of dynamic viscosity from 20 MPa * s to 100 Pa * s in the time range from 2 seconds to 2 minutes.
  • the foamed silica gel is obtained by 20 air-mechanical foaming of a mixture of a solution of 10-70%, mainly 20-50%, sodium silicate, and 1 -15%, mainly 6%, foaming surfactant, from 1 to 6%, mainly 1 up to a 3.5% aqueous solution of acetic acid, with a mass ratio of a solution of sodium silicate with a foaming 25 surfactant and a solution of acetic acid from 100: 1 to 28: 1, mainly 35: 1, based on an aqueous solution of silica sol, containing at least 10 m e.
  • % silica formed during the hydrolysis of a foamed mixture of a solution of sodium silicate with a foaming agent with a pH of 10.9 to 11, 5 and a solution of acetic acid with a pH of 1 to 5 or a solution of a salt of ammonium chloride with a pH of 3 to 8.
  • the process of producing a foamed silica gel and foamed ceramic material based on foamed silica includes the steps of forming a silica sol, foaming a silica sol, forming a foamed gel silica, water release and dehydration of the foamed silica gel to obtain a ceramic foam material based on foamed silica.
  • silica sol occurs as a result of mixing and 5 mutual homogenization of an aqueous solution of an alkali metal silicate, mainly sodium silicate (10-70%) with a foaming surfactant, mainly synthetic hydrocarbon foaming agent, (1-15%) and an aqueous solution of the ash formation activator silica from alkali metal silicate, mainly a solution of acetic acid, acid (1-6%), which initiates the chemical reaction of the transition of alkali metal silicate to a silica sol.
  • an alkali metal silicate mainly sodium silicate (10-70%) with a foaming surfactant, mainly synthetic hydrocarbon foaming agent, (1-15%)
  • an aqueous solution of the ash formation activator silica from alkali metal silicate mainly a solution of acetic acid, acid (1-6%), which initiates the chemical reaction of the transition of alkali metal silicate to a silica sol.
  • alkali metal silicate hereinafter in the preferred embodiment, sodium silicate
  • silica is caused by a chemical reaction of hydrolysis of sodium silicate in an aqueous medium in the presence of ash formation activator 15 to form silicic acid
  • the influence of the ash activating activator on the polymerization of the formed silica monomers and the limitation of this stage of the process from further gelation is determined by the size of the hydrodynamic particle radius in the range up to 50 nm, since it is known that
  • the foaming of the silica sol according to the invention can be carried out predominantly by the air-mechanical method by gas-mechanical dispersion of a mixture of an aqueous solution of an alkali metal silicate and a surfactant and an aqueous solution of an activator of ash formation by any of the known methods of air-mechanical foaming by means of gas-mechanical foam generators, for example by means of foam generators UKPP "PURGA” produced by the applicant ZAO NPO SOPOT, which allows the formation and encapsulation of air-bubble inclusions and the formation of foamed silica substrate due to reduced surface tension forces by the foaming agent.
  • the resulting solid foam of foamed silica has a sufficiently high structural and mechanical resistance to the adverse effects of external factors, such as heat fluxes and wind.
  • concentration of sodium silicate and the chemical properties of the foaming surfactant have a significant impact on the foaming process, and therefore the choice of the concentration of the foaming surfactant in a particular case may depend on its individual foaming ability.
  • foamed silica gel is advisable in the time range from 2 seconds to 2 minutes, during which the mechanical strength of the gel is set to form a subhard mass of foamed silica with a viscosity of up to 100 Pa * s, which, as is known, corresponds to the concept - solid state of the substance [http://chem21.info/info/56093/].
  • foams from known foam generators are usually supplied to the fire source.
  • an energy barrier is achieved that determines the possibility of chemical interaction of individual monomers of silica sol through a layer of dispersion medium that is equilibrium in thickness and occurs in the entire volume mixtures of solutions with a sufficiently high homogeneity. This allows a sufficiently high speed to ensure the transition of the mixture of solutions from the sol state silica to silica gel to form a hardening foamed silica gel.
  • micro- and macroporous structure has a micro- and macroporous structure with a specific surface area of at least 20 m 2 / g;
  • zo is white or yellowish white.
  • the foamed silica gel is preferably obtained by air-mechanical foaming of a mixture of an aqueous solution of 10-70%, mainly 20-50%, sodium silicate, and 1-15%, mainly 6%, with a synthetic hydrocarbon blowing agent, from 1 to 6%, predominantly 1 to 3.5% aqueous solution of acetic acid, with a mass ratio of an aqueous solution of sodium silicate with a foaming surfactant and an aqueous solution of acetic acid from 100: 1 to 28: 1, mainly 35: 1.
  • Foamed silica gel is obtained on the basis of an aqueous solution of a silica sol containing at least May 10. % silica formed during the hydrolysis of a foamed mixture of a solution of sodium silicate with a foaming agent with a pH of 10.9 to 11, 5 and a solution of acetic acid with a pH of 1 to 5 or a salt solution with a pH of 3 to 8, with a hydrodynamic particle radius of silica not more than 50 nm during air-mechanical foaming of a solution of silica sol during the growth of silica monomers to an average diameter of silica sol of 100 nm with a set of mechanical strength in terms of dynamic viscosity from 20 mPa * s to 100 Pa * s in the time range from 2 seconds to 2 minutes.
  • the proposed method can also use solutions of alkali and alkaline earth metal silicates, in particular sodium silicate, as the most common alkali metal silicate in industrial production, and can also be used foaming surfactants of various grades, in particular foaming agents for fire fighting I stamps by-6TST, "Firex" NSV Software TF-6 and others, satisfying the conditions of preservation of stability over time, is in a mixture with an aqueous solution of sodium silicate, and without changing its chemical composition;
  • alkali and alkaline earth metal silicates in particular sodium silicate
  • foaming surfactants of various grades, in particular foaming agents for fire fighting I stamps by-6TST, "Firex" NSV Software TF-6 and others, satisfying the conditions of preservation of stability over time, is in a mixture with an aqueous solution of sodium silicate, and without changing its chemical composition
  • the soluble alkali metal silicate of lithium, potassium, sodium commonly called “liquid glass” is a viscous liquid with the general chemical formula R2O mSi02 pNgO (where R2O is an alkali metal oxide, m is the module of liquid glass) with a density of 1400-1500 kg / m 3 and a dynamic viscosity coefficient of up to 1 Pa s.
  • the viscosity of the solution increases by 4-500 times compared with the viscosity of water (0.001 Pa s, 20 ° C).
  • Such a change in the viscosity of aqueous solutions used to extinguish fires is practically unattainable when using 5 organic or inorganic thickeners.
  • the density of the solution increases significantly, which contributes to an increase in the kinetic energy of the movement of the jet of fire extinguishing solution or foam in comparison with the energy of the jet of water directed into the combustion chamber at the same speed, while the range of the jet of fire extinguishing solution or foam also increasing.
  • the designated interval of the silicate module allows you to significantly reduce the cost of its production, providing a positive economic effect on the created product. However, it is allowed to use another module with 20 small deviations from the set in the range of ⁇ 0.5.
  • the selection of the concentration of reagents was based on the conditions that the set hardness of the foamed substrate from a silica sol during the transition to the gel state was accompanied by a set of viscosity up to 100 Pa * s for a specified time interval from 2 seconds to 2 minutes.
  • the lower value of the set time interval (2 s) was determined based on the minimum possible time of homogenization of a mixture of solutions with simultaneous foaming.
  • the upper value of the set time interval (2 min) is determined based on the general rules for the destruction of foams based on foaming surfactants [http://www.xumuk.ru/colloidchem/200.html] the result of the outflow of fluid from the foamed substrate after 2 minutes exposure and, as a consequence, a visual deterioration in the structural and mechanical parameters of the foam.
  • silica sol When homogenizing a mixture of a hardener-catalyst solution (acetic acid solution 5) and a working solution consisting of a surfactant and an alkali metal silicate, silica sol can be obtained by any of the known methods, which is promising for producing a foamed silica gel.
  • the key parameters in this case are the concentration of silicate and hardener. Examples of justification of process parameters are shown below.
  • Stability is characterized by a period of time during which the foam did not change its volume (i.e., a decrease in volume of 10%).
  • the structure of the foam material was evaluated visually after hardening and drying (after about 3 days at a temperature of 25 ⁇ 5 ° C).
  • the multiplicity of the foam determined by the weight method.
  • Fire extinguishing properties - extinguishing time of a model fire 1A Heat resistance - preservation by the material of its structure and properties when heated 20 to a certain temperature, above which partial melting of the surface layer begins and its compaction.
  • Example 1 Used aqueous solutions of foaming agent 6TCT, sodium silicate and acetic acid. Homogenization by stirring the mixture of solutions was carried out with an IKA C-MAG HS 7 magnetic stirrer at a speed of 25 rotation of 500 rpm, viscosity was measured with a Brookfield DV2T viscometer.
  • Example 2 Used aqueous solutions of foaming agent PO 6TC, sodium silicate and acetic acid. Homogenization by mixing the mixture of solutions was carried out with an IKA C-MAG HS 7 magnetic stirrer at a speed of 500 rpm, viscosity was measured with a Brookfield DV2T viscometer. The results of the study at various concentrations of acetic acid solution and with a ratio of its amount in a solution of sodium silicate and surfactant in the range of 1-6% are shown in table 2. Table 1.
  • Example 3 To initiate the chemical formation of nanosized silica in an aqueous solution, the solutions were interacted by hydrodynamically dispersing them in the stem of the foam generator of the air-mechanical principle of operation. For this, a solution of sodium silicate with a surfactant was used as an ejecting substance, and a solution of acetic acid was used as an ejected substance. Depending on the concentration of solutions of acetic acid and sodium silicate, a silica sol was formed, characterized by a hydrodynamic radius of less than 50 nm. The hydrodynamic radius of silica particles was calculated by dynamic light scattering at 2 sec. Exposure of the solution after mixing sodium silicate and acetic acid. The results of the study are shown in table 3.
  • Example 4 The characteristics of the hardness set during the sol-gel transition of sodium silicate in the presence of acetic acid to silica gel are presented in table 4, where the letter H indicates that in these cases the stage of transition to the gel has not been reached in the range up to 2 minutes, and the number 1 indicates that in these cases, viscosity increases in the range up to 1 second with an experimental measurement error of not more than ⁇ 0.5 s.
  • the most optimal use of the range is from 10 to 70%, since in these intervals it is possible to set the hardness of the silica gel in the specified interval.
  • Example 5 For the formation of the foam structure of a solution of silica sol after mixing solutions “A” and “B”, a foam generator was used, operating on the principle of air-mechanical dispersion. The type of foam generator used contributed to the ejection rate of solution B at 6% concentration. The characteristics of the resulting foamed silica gel are presented in table 5.
  • the multiplicity of the foam - a value equal to the ratio of the volumes of the foam and the solution that went into the formation of the foam [httpJ / pozhproekt.ru / enciklopediya / kratnost-peny] was set in the maximum and minimum expression depending on the technological settings of the foam generator. Air supply speed - 5 m / s. Table 5.
  • sodium silicate concentrations of more than 50% is also possible, but not advantageous, since in this case the formation of foam is hindered by the high viscosity of the sodium silicate solution.
  • the most appropriate range of concentration of sodium silicate for the formation of stable silica foams with subsequent hardening may be from 10 to 50%.
  • the foamed silica gel passes into a dehydrated state (water content of not more than 5%), characterized by a specific surface area of at least 20 m 2 / g.
  • Example 1 The wetting ability of a solution of sodium silicate with a foaming agent was determined depending on the type and concentration of the foaming agent PO 6TsT and PO 1 NSV.
  • a clamping device for immersing a sample of cotton cloth in a working solution in accordance with GOST R 50588 p.5.9.1, a mechanical stopwatch SOSpr-2b-2-000, round-shaped samples from unbleached cotton cloth with a diameter of 30 mm in accordance with GOST R 50588 p .5.9.1.
  • silicates of other alkaline and alkaline-earth metals in particular hydrated potassium or lithium silicates
  • sodium silicate solutions is economically preferable due to its availability, mass industrial production and lower cost in comparison with silicates of other alkali metals, as well as its unlimited solubility even in cold
  • hydrochloric acid solution or ammonium chloride solution can also be used as an activator of ash formation of silica from alkali metal silicate, which also initiate hydrolysis of sodium silicate with
  • acetic acid solution is preferable, since it provides the most uniform set of hardness throughout the volume (no flocculation and clumping is observed), does not require special storage and operating conditions, aqueous solutions of acetic
  • the fire extinguishing efficiency of the proposed foamed silica gel compared with the fire extinguishing efficiency of water and air-mechanical foam was tested according to the method GOST 51057-2001 when extinguishing a model center of fire 1A.
  • the tests were carried out in the open air at a temperature corresponding to the operating temperature range of the fire extinguisher, and a wind speed not exceeding 5 m / s, in the absence of precipitation.
  • the model fire was a wooden stack in the form of a cube.
  • the stack was placed on a solid support in such a way that the distance from the base of the stack to the supporting surface was 400 mm.
  • Softwood bars of at least third grade according to GOST 8486 with a cross section of 40 mm, a length of 500 mm, and lumber moisture content of 15% were used as combustible material.
  • the parameters of the model fire are presented in Table. 12
  • the stack of the model fire site was laid out in such a way that the bars of each subsequent layer were perpendicular to the bars of the underlying layer.
  • channels of a rectangular section 40x40x500 mm in size were formed throughout the entire volume.
  • the parameters of the metal pan for a combustible liquid, which was placed under the stack, correspond to the data in table 13.
  • the fire center was given rotation at a speed of 2 rpm, which allowed the extinguishing substance to be supplied to each side of the fire in sequence.
  • Extinguishing was carried out using an OVP-40 air-foam fire extinguisher.
  • the supply of extinguishing agent was supplied through a low barrel with a flow rate of 1 l / s at a pressure of 0.5 MPa.
  • the distance from the trunk to the fire was 4 meters.
  • a fire extinguisher was installed permanently.
  • a characteristic feature of the proposed fire extinguishing agent is the complete absence of re-ignition of the treated surface with prolonged exposure to direct fire, in contrast to the use of conventional known fire extinguishing agents.
  • This effect is achieved by a combination of several factors that determine the effectiveness of fire extinguishing with hardening foams based on the proposed foamed silica gel.
  • phase sol-gel transition is accompanied by a very high adhesion of the gel to the substrate during the transition to the solid state. This feature allows the formed material to be fixed on vertical surfaces. Moreover, the presence of micellar structures of the surfactant in the form of bubble inclusions formed by 20 air-mechanical dispersion blocks the penetration of oxygen through closed porosity, similar to the action of ordinary foams.
  • foamed silica on the surface of a solid material makes repeated ignition impossible due to heat resistance up to 1000 ° C with a layer thickness of about 1 cm or more.
  • alkali metal silicate located in the main aqueous solution during evaporation of water forms a glass film on the surface of the burning material, which also slows down and stops the combustion process.
  • the proposed material not only has improved 5 physical and mechanical characteristics, but also exhibits unique fire extinguishing properties with a fundamentally new fire extinguishing mechanism.
  • the unique physical and mechanical properties of the proposed foamed silica material also allow it to be used as a non-combustible and non-flammable heat-insulating material, as a supporting heat-insulating material, a catalyst support, a filter, an absorber, a non-combustible or non-flammable lightweight building material, and as a coating for use in thermal diffusion processes , for sound insulation, for humidity control or as
  • the use of the proposed fire extinguishing means in comparison with the known fire extinguishing means can significantly reduce the temperature of the combustion surface due to the heat consumption for evaporation

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Silicon Compounds (AREA)

Abstract

L'invention concerne le domaine de production de sol-gel par procédé de gel de silice expansé qui peut être utilisé en tant qu'agent d'extinction d'incendies pour prévenir les explosions ou les incendies et également en tant que matériau isolant ou de remplissage en construction ou dans d'autres domaines de l'industrie. Le gel de silice expansé est obtenu par un moussage aérien et mécanique d'un mélange de solution aqueuse de silicate d'un métal alcalin avec un tensioactif moussant et une solution aqueuse d'un activateur de formation de sol de silice à partir du métal alcalin sous la forme d'une solution aqueuse d'acide acétique, d'acide chlorhydrique ou de chlorure d'ammonium. L'invention assure la possibilité d'utilisation du sol-gel en tant qu'agent d'extinction d'incendies.
PCT/RU2015/000819 2015-03-26 2015-11-25 Gel de silice expansé, son procédé d'utilisation et de production WO2016153385A1 (fr)

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RU2015110625/05A RU2590379C1 (ru) 2015-03-26 2015-03-26 Вспененный гель кремнезема, применение вспененного геля кремнезема в качестве огнетушащего средства и золь-гель способ его получения
RU2015110625 2015-03-26

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RU2720416C1 (ru) * 2019-12-27 2020-04-29 Общество с ограниченной ответственностью "Техно" Способ получения вспененного гидрогеля кремниевой кислоты
CN114669003A (zh) * 2022-04-11 2022-06-28 安徽理工大学 一种用于治理深部易燃煤层引发的大面积火区的凝胶泡沫材料

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RU2672945C1 (ru) * 2018-01-17 2018-11-21 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Способ взрывопожаропредотвращения и твердопенного тушения вспененным гелем кремнезёма и устройство для его осуществления
RU2668749C1 (ru) * 2018-03-29 2018-10-02 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Огнетушитель для взрывопожаропредотвращения и твердопенного тушения
RU2668753C1 (ru) * 2018-03-30 2018-10-02 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Огнетушитель твердопенного тушения
RU2668747C1 (ru) * 2018-04-03 2018-10-02 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Огнетушитель химический пенный с эжекторным смесителем-пеногенератором
RU183793U1 (ru) * 2018-04-03 2018-10-02 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Огнетушитель химический с эжекторным смесителем-пеногенератором
RU2701419C1 (ru) * 2019-01-24 2019-09-26 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Способ предотвращения и тушения крупномасштабных лесных, промышленных и аварийно-транспортных пожаров быстротвердеющей пеной и устройство для его осуществления
RU190535U1 (ru) * 2019-02-06 2019-07-03 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Огнетушитель с U-образным корпусом для взрывопожаропредотвращения и твердопенного тушения
RU2699078C1 (ru) * 2019-02-06 2019-09-03 Общество С Ограниченной Ответственностью Нпо "Современные Пожарные Технологии" Огнетушитель газогенераторный для взрывопожаропредотвращения и твердопенного тушения
WO2020197426A1 (fr) * 2019-03-27 2020-10-01 Геннадий Николаевич КУПРИН Extincteur pour la prévention de feux explosifs et à extinction par mousse solide
RU2694924C1 (ru) * 2019-04-03 2019-07-18 Общество с ограниченной ответственностью "ПолимерСинтез" Огнетушащее и огнезащитное средство
RU2753652C1 (ru) * 2020-04-30 2021-08-19 Общество с ограниченной ответственностью "Горно-техническое учреждение пенообразования" Пеногель

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CN114669003A (zh) * 2022-04-11 2022-06-28 安徽理工大学 一种用于治理深部易燃煤层引发的大面积火区的凝胶泡沫材料

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