Thermally activated fire-extinguishing nanocapsule and method for producing same

Abstract

The present group of inventions relates to the field of extinguishing fires, and can be used for preventing flaming combustion and extinguishing fires in confined spaces. In a thermally activated fire-extinguishing nanocapsule, 25-30 wt.% of the nanocapsule is comprised of a core of fire extinguishant encapsulated in a cured inner shell that constitutes 65-55 wt.% of the nanocapsule, protected by a cured reinforcing outer shell that constitutes 10-15 wt.% of the nanocapsule. The inner shell is produced from an aqueous polyvinyl alcohol solution. The outer shell is produced from urea, ammonium chloride, resorcinol and formalin. First, the fire extinguishant is dispersed in a solution of polyvinyl alcohol 16 / 1 and water for 10 minutes at 30-35°C and 1000-1500 rpm until a nanoemulsion is formed. Then a dry mixture of urea, ammonium chloride and resorcinol, or a mixture thereof dissolved in water, is added and stirred for 60 minutes at 300-400 rpm, resulting in coacervation and coalescence. As a result of the claimed method for producing thermally activated nanocapsules, the cured nanocapsules have a size of 250-950 nm and can therefore be used in microelectronic components and gadgets.

Description

[0001] THERMALLY ACTIVATED FIRE EXTINGUISHING NANOCAPSULATE AND A METHOD FOR ITS PRODUCTION FIELD OF TECHNOLOGY

[0002] The invention relates to an independent “smart” innovative means for local extinguishing of flame and / or flameless (thermal decomposition) combustion in closed spaces using thermally activated fire extinguishing nanocapsules (TANCs).

[0003] PRIOR ART

[0004] The "smartness" of nanocapsules has not previously been postulated in patents related to fire-fighting equipment. "Smartness" is inherent to polymers—high-molecular compounds capable of strongly reacting to small changes in the external environment in a pre-programmed manner using nanotechnology. Therefore, programming in this case should be understood as the creation of a program (algorithm) in the form of a sequence of actions of the TANP elements to solve the problem of opening the walls of the TANP housing and triggering the release of the extinguishing agent from the TANP core using thermophysical and chemical processes.

[0005] Thus, the "intelligent" operation principle of the TANP is based on programmed thermophysical and chemical processes that pulse the fire extinguishing mechanism when the ambient temperature rises or upon direct contact with a flame. As the ambient temperature rises, thermophysical and chemical processes occur that affect the TANP shell walls, programmed for specific temperature parameters of opening, coupled with a simultaneous change in the aggregate state of the fire extinguishing agent and an increase in internal excess pressure in the TANP core. These processes result in: a) the breakdown of chemical bonds between the components of the TANP shell walls; b) the transition of the fire extinguishing agent within the TANP core from a liquid to a gaseous state, with an increase in excess pressure acting on the TANP shell walls; c) the release of the gaseous fire extinguishing agent beyond the TANP shell walls, subsequently extinguishing the fire.

[0006] The described process is a pulsed (explosive) release of extinguishing agent encapsulated within the core of the fire extinguishing agent into the surrounding environment at a temperature above the critical values ​​programmed within the walls of the fire extinguishing agent's casing. This enables effective extinguishing of flaming and flameless fires, primarily in the initial stages of their development, regardless of the method and location of the fire extinguishing agent's placement. Due to the uniform integrity of the fire extinguishing agent's casing walls, the release of the extinguishing agent will predominantly occur toward the temperature closest to the activation temperature.

[0007] The extinguishing principle of a fire extinguishing agent based on fluorine-containing derivatives consists of a combination of physical and chemical properties of simultaneous intensive heat removal (approximately 70%) from the heat source, including the flame, which leads to cooling of the burning zone to the temperature of combustion termination, as well as flame inhibition (30%). That is, when the fire extinguishing agent is ejected beyond the walls of the TANP housing shell, the following occurs: a) active displacement of oxygen from the flame combustion zone; b) interaction with free hydrogen; d) release of halogen with the formation of "heavy" free radicals; e) termination of kinetic chains at the chemical level of combustion; f) destruction of the flame column with a sharp decrease in temperature, disrupting the chains of substance decomposition processes; g) the condensation process begins, the decomposition chains of substances are stopped (inhibited); h) combustion fades out and ceases.

[0008] Currently, microencapsulated fire extinguishing methods are actively used in fire extinguishing equipment. The main problems in the creation of microcapsules are: - the creation of stable over time walls of the microcapsule housing shells to preserve the fire extinguishing agent; - the possibility of destruction of the walls of the microcapsule shells under certain parameters of external influences leading to their destruction. The field of creating the walls of the housing shells for nanocapsules remains underdeveloped and poorly researched, as follows from patents RU 2469 761 C1 (publication date 2011), RU 2555 887 C2 (publication date 2012), RU 2 731 599 C1 (publication date 2019), RU 2 748 845 C1 (publication date 2021), Chinese patent CN 115101812 A (publication date 2022).This situation is associated with the most complex process in the creation of the walls of the shells of the microcapsules, the selection of chemical reagents and their connection (cross-linking) in chemical reactions into a single wall of the shell of the housing, which has strength and ensures: a) the preservation of the fire-extinguishing agent in the core of the microcapsules; b) low permeability of reagents from the external environment; c) "smart" action based on thermophysical processes triggering the mechanism of opening (destruction) of the walls of the shell of the microcapsules of the housing at certain (specified) temperatures of the environment with the subsequent release of the fire-extinguishing agent.

[0009] The following are known from the level of fire-fighting technology: a) microencapsulated fire extinguishing agents; b) methods for obtaining microencapsulated fire extinguishing agents; c) the use of microencapsulated fire extinguishing agents as fire extinguishing agents (RU 2 469 761 C1 (publication date 2011), RU 2555 887 C2 (publication date 2015), RU 2 559 480 (publication date 2015), RU 2 622 303 C1 (publication date 2016), RU 2631 868 (2017), RU 2 631 867 (publication date 2017), RU 2748 845 C1 (publication date 2021), CN 115101812 A (Chinese patent, publication date 2022), and others).

[0010] Similar patents RU 2 616 940 (published in 2017) and RU 2 628 375 (published in 2017) describe a polymer composition for producing heat-activated fire extinguishing materials comprising a polymer shell and core in each microcapsule, namely: a) an aqueous dispersion of a polymer as a binder; b) a mineral filler and fibrous material; c) a microencapsulated fire extinguishing agent as a carrier gas component with a boiling point from -155°C to +10°C. The carrier gas, combustion phlegmatizer, and combustion inhibitor are present in the following weight ratio: carrier gas 5-50%, combustion phlegmatizer 30-70%, combustion inhibitor 1-25%. The disadvantages of this method include their production, which makes it virtually impossible to ensure precise dosing of the specified components for each microcapsule. This eliminates the possibility of forming a homogeneous and integral polymer shell with stable characteristics.Synthesis cycles (under conditions of constant mixing during production) can cause delamination of the agent matrix, which can lead to variations in activation temperatures, non-uniform component concentrations, and possible reduction in fire extinguishing effectiveness. In most cases, polymer shells cross-linked without stabilization exhibit numerous hidden defects that become apparent immediately after vulcanization, resulting in a short shelf life before active agent loss (20% to 50% of the core mass) occurs within the first 10 days after manufacture.

[0011] Fire extinguishing agents based on nanotechnology are of practical relevance for fire-fighting equipment, which is served by the development of fire extinguishing nanocapsules, for example, for lithium-ion batteries used in cell phones (CN 115101812 A (Chinese patent, publication date 2022)).

[0012] The technology for producing nanocapsules is presented in Chinese patent CN 115101812 A (publication date 2022). The chemical composition of the nanocapsule shell walls consists of a dry mixture of sodium caseinate and D-lactose hydrate dissolved in water. The temperature parameters for stirring the nanocapsule shell wall solution are 90 °C with the stirrer shaft rotating at 1000 rpm for mixing. The time parameters are: 0.5 h to obtain nanocapsules with a size of 280 nm; 1 h to obtain nanocapsules with a size of 300 nm; 2 h to obtain nanocapsules with a size of 450 nm; 3 h - the particle size is 1.5 μm.The main and significant disadvantages of this solution include: a long, complex and intermittent production process, namely, after the creation of a nanoemulsion and the receipt of a sediment (nanocapsules with a weak shell wall), a freeze-drying process is performed. This consists of initially freezing the sediment at a temperature of -20 °C for 11-13 hours in a freezer, then transferring it to a vacuum freeze-dryer and maintaining it at a temperature of -50 °C for 46-50 hours. It is also necessary to note the poor solubility of sodium caseinate in water; small lumps are present, which do not disappear even when mixed with D-lactose hydrate, due to which the nanoemulsion contains not only the formed nanocapsules, but also many micro lumps from sodium caseinate and D-lactose hydrate.The resulting nanocapsules are intended exclusively for lithium batteries and are not intended to prevent the occurrence of flaming combustion or extinguish fires of classes A, B, C, E in closed spaces.

[0013] Also known is a thermally activated fire-extinguishing nanocapsule and a method for producing it, described in patent CN117442920 (publication date 2024). Perfluorohexanone is used as the main fire-extinguishing agent in fire-extinguishing nanocapsules. The shell of the nanocapsules consists of chitosan, which envelops the fire-extinguishing agent (the core of the nanocapsule) under high temperature conditions. A gelatin solution and a solution of Arabic gum are used as emulsifiers to form a stable emulsion with the fire-extinguishing agent and cooling agent used in the core material, which facilitates the application of a coating of modified chitosan. An invention similar to the claimed solution in the chemical essence of the formation of the wall of the capsule body shell and the achieved effect is known, presented in patent RU No. 2 469 761 C1 (publication date 2011).), which presents a microencapsulated fire extinguishing agent with a polymer shell and a core of fire extinguishing liquid (perfluoroethyl-perfluoroisopropyl ketone or dibromomethane, or mixtures with other bromofluoro-containing). The invention discloses methods for producing: - a microencapsulated fire extinguishing agent; - fire extinguishing composite materials made in the form of pastes, plates, films, articles, solid foams, fabrics; - a fire extinguishing coating containing in its composition the said microencapsulated fire extinguishing agent. Microcapsule - a capsule of various shapes and consisting of a thin shell made of a polymer or other material, spherical or irregular in shape, with a size of 1 μm to 2 mm (for therapeutic or prophylactic purposes up to 1000 μm), containing solid or liquid active ingredients with or without the addition of auxiliary substances.The stability of the microcapsules is ensured by the perfluoroethyl-perfluoroisopropyl ketone core, enclosed in a resorcinol-urea-formaldehyde resin shell, with nanosized montmorillonite platelets incorporated into the microcapsule shell walls. The polymeric material of the microcapsule shell wall was a complex of polyvinyl alcohol (the brand is not specified in the patent) with urea-resorcinol-formaldehyde resin, with urea, resorcinol, and formaldehyde mixed in water. The microcapsule shell walls were formed by the sorption of coacervate microdroplets on the surface of emulsion droplets and their coalescence (fusion) to form liquid shells. When a mixture of urea, formaldehyde, and resorcinol was added in the form of aqueous solutions, the mineral filler nanoparticles were predominantly concentrated in the microdroplets of the coacervate phase.Then, to harden the shell, the temperature was increased to 45°C and maintained at the specified temperature for 3.5 hours, cooled to room temperature, the resulting microcapsules were washed with water, filtered and dried. To carry out coacervation and subsequent production and hardening of the shell, two solutions were obtained, differing only in the concentrations of the components: 1st solution (for the coacervation process): 0.38 g of urea, 0.9 g of resorcinol and 2.25 ml of formalin (37% by weight aqueous solution of formaldehyde) were dissolved in 5.25 ml of distilled water; 2nd solution (for the shell hardening process): 0.38 g of urea, 1.28 g of resorcinol and 5.25 ml of formalin were dissolved in 7.5 ml of distilled water. Thirty ml of a 5% by weight aqueous solution of polyvinyl alcohol was placed in a stirrer, and 18 ml of perfluoroketone was added while stirring to form an emulsion. 28 ml of a suspension of exfoliated montmorillonite nanoparticles was added to the resulting emulsion, and the temperature was raised to 35°C.To carry out the coacervation process, the aforementioned first urea-resorcinol-formaldehyde solution and 2 ml of sulfuric acid (10% by weight) were then added. The reaction mixture was then heated to 45°C, the second solution was added, and the mixture was held for 3.5 hours to harden the shell. After cooling to room temperature, the microcapsules were filtered, washed with distilled water, and dried. This yielded a microencapsulated fire extinguishing agent according to the invention, containing microcapsules with a diameter of 50-200 µm.

[0014] The disadvantages of the known solution include: a) a separate montmorillonite preparation step, which not only complicates the microencapsulation process but also makes it more expensive; b) insufficiently stable shell walls of the microcapsules, despite the fact that the loss of extinguishing agent from the microcapsule core has been somewhat slowed. Furthermore, the disadvantages of the resulting "microencapsulated extinguishing agent" for fire suppression include:

[0015] 1. Micro-size, which limits their use in micro-components of electronics and gadgets whose elements are prone to fire hazards, for example, batteries or processors that require thermally activated nanoparticles for fire suppression.

[0016] 2. The impossibility of extinguishing fires of classes A, B, C, E in closed spaces without human intervention

[0017] 3. The use of urea-resorcinol-formaldehyde resin as a curing agent, which is unstable over time, leading to the destruction of the shell of the wall of the microencapsulated fire extinguishing agent.

[0018] The present invention is aimed at creating a fire extinguishing agent in the form of thermally activated fire extinguishing nanocapsules used to prevent the occurrence of flaming combustion and extinguish fires of classes A, B, C, E in closed spaces without human intervention.

[0019] DISCLOSURE OF THE INVENTION

[0020] The present invention consists in creating a thermally activated fire-extinguishing nanocapsule (TANF) representing a core of a fire-extinguishing agent encapsulated in a cured inner shell of a polyvinyl aqueous solution, protected by a reinforcing outer shell of a mixture of chemical compounds of urea, ammonium chloride, resorcinol and formalin, in percentage terms of the total mass: core (25-30); inner shell (65-55); outer shell (10-15), and its nanosize is 250-950 nm. Perfluoro (2-methyl-3-pentanone) or 1, 1,2, 2, 3,3,4-heptafluorocyclopentane, as well as a combination thereof in equal proportions, are used as the fire-extinguishing agent. The inner lining is a chemical solution of 16 / 1 grade polyvinyl alcohol and water, or a mixture of chemical compounds of urea, ammonium chloride and resorcinol, or a mixture of them, dissolved in water.

[0021] The method for producing thermally activated fire-extinguishing nanocapsules involves dispersing the fire extinguishing agent in a polyvinyl alcohol aqueous solution to form a nanoemulsion. A mixture of urea, ammonium chloride, and resorcinol is added, followed by mixing, coacervation, and coalescence according to a specific algorithm to harden the shell wall of the nanocapsules. To obtain the nanoemulsion, the fire extinguishing agent is added to the polyvinyl alcohol aqueous solution and dispersed at a temperature of 30-35°C for 10 minutes while an asynchronous motor is running at 1000-1500 rpm., to harden the outer shell, a dry mixture of chemical compounds of urea (0.6% of the total mass), ammonium chloride (14% of the total mass) and resorcinol (25% of the total mass) or a solution of chemical compounds of urea (0.6% of the total mass), ammonium chloride (14% of the total mass) and resorcinol (25% of the total mass) dissolved in water (8.2% of the total mass) is added to the nanoemulsion and mixed at a temperature of 30-35°C for 60 minutes while the asynchronous motor is running at 300-400 rpm. At the first stage, the nanoemulsion is heated to a temperature of 35-40°C, formalin (3.6% of the total nanoemulsion) is added, formalin (grade: 37-41% by weight aqueous solution of formaldehyde) diluted in water (8.2% of the total nanoemulsion) and stirred for 2 hours, after which the temperature is increased to 45-48°C and stirred for 3-4 hours, at the following stages the temperature is gradually increased from 30-35°C to 75°C-80°C while the asynchronous motor is operating at 300-400 rpm., formalin is added to the mixture of nanocapsules and water.

[0022] To achieve nanoscale capsule size, this invention proposes first using a physical method in the form of dispersion, followed by a physicochemical method in the form of coacervation and coalescence. During the dispersion process, the fire extinguishing agent is uniformly distributed in a polyvinyl alcohol aqueous solution (dispersant) as nanoparticles, forming a nanoemulsion, under turbulent (vortex) mixing. Nanoscale is achieved through the use of a high-speed propeller or turbine mixer with an asynchronous motor operating at 1000-1500 rpm. To achieve a uniform response temperature, it is proposed to program the opening of the nanocapsule shell walls by predetermined hardening during curing by increasing the cooking temperature over time.The technologies for the production process and chemical composition of the shell walls of microcapsules using the coacervation and coalescence methods are currently optimal and inexpensive in terms of equipment and scaling up the production of fire-extinguishing nanocapsules.

[0023] The novelty of the invention consists in: a) the creation of a thermally activated fire extinguishing nanocapsule containing a core of a fire extinguishing agent encapsulated in a hardened inner shell protected by a hardened reinforcing outer shell obtained from urea, ammonium chloride, resorcinol and formalin.

[0024] b) in the creation of fire-extinguishing nanocapsules using a dispersion method. A nanocapsule is a spherical polymer shell of nanometer size (from 100 nm to 999 nm) with an empty interior that can contain various substances. This means that nanocapsules are significantly smaller than microcapsules, which is an advantage, opening up a wide range of applications in various fields of science and technology.

[0025] The present invention consists of developing a method for producing a complex two-layer polymer wall of the TANP housing shell by combining high-molecular chemical reagents capable of reacting to temperature changes in the external environment in a pre-programmed manner.

[0026] The objective of achieving the novelty of the invention, namely, the nanoscale size of the TANP, was achieved through two methods: a physical method—dispersion by adjusting the speed of the disperser and dispersing nozzle; and a physicochemical method—simple coacervation, which involves changing the solution temperature and diluting the system. The invention of a thermally activated fire-extinguishing nanocapsule for fire safety at various protected facilities has a wide range of applications, from standalone use to integrated use as an additional element in technical autonomous and integrated fire-extinguishing devices and systems.

[0027] As an independent application, TANP can be used to protect: a) small volumes containing electrical components (sockets, switches, junction boxes, etc.); b) internal volumes of household and industrial electrical devices and appliances; c) internal volumes of engine and distribution compartments of vehicles, etc. TANP can also be introduced as a filler into: resins, electrolytes, liquid curable rubbers and foams, latex, paint and varnish coatings, and other materials and products.

[0028] As an additional fire protection element, TANP can be used in stand-alone (fire extinguishers, stickers, tapes, cords, etc.) and integrated (automatic powder fire extinguishing systems) fire extinguishing devices and systems to protect: a) distribution boards and cabinets, control panels, engine compartments and other enclosed objects with a protection rating of IP20 and higher; b) warehouse, industrial, public, administrative and residential premises. The purpose of such protection is to prevent the occurrence of flame (flameless) combustion and extinguish fires of classes A, B, C, E. EMBODIMENTS OF THE INVENTION.

[0029] Figure 1 shows a schematic representation of a thermally activated fire-extinguishing nanocapsule in a three-dimensional cross-section, in which the following positions are indicated: 1 - double shell, 2 - fire-extinguishing agent core. Double shell 1 consists of an outer shell 1.1 and an inner shell 1.2.

[0030] Fig. 2 shows thermally activated, uncured fire-extinguishing nanocapsules after 10 minutes of dispersion in a nanoemulsion. Nanoscale 250-950 nm.

[0031] One cycle of synthesis of TANP production includes the following stages:

[0032] 1. Polyvinyl alcohol is added to water heated to a temperature of 80-90°C with constant stirring until the polyvinyl alcohol is completely dissolved in water, and then the resulting polyvinyl aqueous solution of the material of the inner shell of the TACP housing is cooled to a temperature of 30-35°C.

[0033] 2. The fire extinguishing agent perfluoro (2-methyl-3-pentanone) is added in a thin stream to the solution described in step 1 at a temperature of 30-35°C with simultaneous dispersion for 10 minutes while the asynchronous motor is running at 1000-1500 rpm. At the specified speed, the nanoscale size of the uncured fire extinguishing nanocapsules reaches 250-950 nm within 10 minutes (Fig. 2), which, in this case of the technology, cannot be considered a significant variation in size. When the asynchronous motor is running at speeds from 400 rpm to 1000 rpm, TANP microcapsules are formed (the lower the speed, the larger the size of the nanocapsules and microcapsules). The nanoemulsion acquires a milky white color.

[0034] 3. In parallel with stage 2, one of two types of hardening mixture is prepared in a separate chemical container for the outer shell of the TANP housing:

[0035] 3.1 Dry mixture: the reagents urea, ammonium chloride and resorcinol are mixed in dry form;

[0036] 3.2 Liquid mixture: the dry mixture prepared in accordance with item 3.1 is added to water at room temperature and completely dissolved in it.

[0037] 4. After 10 minutes of hardening the shell wall of the nanocapsule body, add the dry mixture described in step 3 to the nanoemulsion described in step 2 and stir for 60 minutes while the asynchronous motor is running at 300-400 rpm.

[0038] 5. Formaldehyde is mixed with water at room temperature. 6. The nanoemulsion described in step 4 is heated to 35-40°C after 60 minutes, after which the formalin obtained in step 5 is added to enhance the hardening of the nanocapsule shell wall. The mixture is stirred for 2 hours while the asynchronous motor is running at 300-400 rpm. The nanoemulsion changes color from milky white to beige-pink.

[0039] 7. The nanomulsion described in step 6 is heated to a temperature of 45-48°C after 2 hours to enhance the hardening of the shell wall of the nanocapsules and stirred for 3-4 hours with the asynchronous motor running at 300-400 rpm. 8. The nanomulsion described in step 7 is heated to a temperature of 50°C after 3-4 hours and stirred for 18 hours with the asynchronous motor running at 300-400 rpm.

[0040] 9. The process described in step 8 is stopped for cooling and until a precipitate forms in the form of hardened TANP nanocapsules, after which the liquid phase of the nanoemulsion is drained through a filter, and the hardened beige-pink TANP nanocapsules are washed with running water at least 4-5 times through a filter, then the TANP nanocapsules are weighed (the mass of the TANP nanocapsules relative to the mass of the nanoemulsion described in step 2 should be 30-40% less).

[0041] 10. The TANP nanocapsules obtained in step 9 are filled with water at room temperature in a volume twice the volume of the capsules, followed by heating the mixture to 40°C with constant stirring and the asynchronous motor operating at 300-400 rpm.

[0042] 11. When the temperature of the mixture reaches 40°C, to enhance the hardening of the shell wall of the nanocapsules, 8% of formalin is added based on the mass of the nanocapsules and the temperature is increased to 50°C while the asynchronous motor is operating at 300-400 rpm.

[0043] 12. Then, the temperature of the mixture described in step 11 is increased to enhance the hardening of the shell wall of the nanocapsule body every hour by 5°C to 75°C with constant stirring while the asynchronous motor is operating at 300-400 rpm.13 When the temperature reaches 75°C, the mixture is stirred as described in step 11 for 18-20 hours while the asynchronous motor is operating at 300-400 rpm.

[0044] 14. The process described in step 13 is stopped for cooling and until a precipitate forms in the form of hardened TANP nanocapsules, after which the liquid phase of the nanoemulsion is drained through a filter, and the TANP nanocapsules that have formed, from beige-sand to sand-pink (burgundy) in color, are washed with running water at least 4-5 times through a filter, then the TANP nanocapsules are weighed (the mass of the TANP nanocapsules, relative to the mass of the TANP nanocapsules described in step 9, may be less than no more than 10%).

[0045] 15. The nanocapsules obtained in step 14 undergo quality control and are sent for drying under natural conditions at room temperature for 24 hours or using freeze-drying.

[0046] 16. After drying, the nanocapsules are sorted and packaged for further sale.

[0047] The quantitative indicators for the preparation of TANP (according to pos. (a) and (b)) are presented using the example of 1000 g of water and 500 g of perfluoro (2-methyl-3-pentanone).

[0048] Polyvinyl alcohol (grade 16 / 1 according to Russian qualification) in the amount of 26 g is added to 1000 g of water and stirred until completely dissolved, as described in step 1.

[0049] When dispersing, 500 g of perfluoro(2-methyl-3-pentanone) fire extinguishing agent is added to the solution in a thin stream, as described in step 2. In step 3, one of two options for the hardening mixture is prepared. Option 1 (dry mixture): a chemical mixture of urea (10 g), ammonium chloride (14 g), and resorcinol (25 g) is prepared for 500 g of fire extinguishing agent, and the prepared dry mixture is added, as described in step 4. Option 2 (liquid mixture): a dry mixture of urea (10 g), ammonium chloride (14 g), and resorcinol (25 g) is prepared for 500 g of fire extinguishing agent and dissolved in 145 g of water, then the prepared solution is added, as described in step 4.

[0050] In step 5, formalin (grade: 37-41 percent by weight aqueous formaldehyde solution) is prepared, where formalin (63 g) and water (145 g) are mixed together and the prepared solution is added to the nanoemulsion, as described in step 6.

[0051] Foaming may occur during mixing of the nanoemulsion. To eliminate foam bubbles, add 1-3 drops of 1-octanol, a chemical reagent that acts as an antifoaming agent, during mixing.

[0052] Basic equipment for producing TANP: 1) Disperser with dispersing attachment and propeller stirrer attachment; 2) Hotplate with heating element, step-by-step electronic control of temperature and time; 3) Thermocouple; 4) Synthesis container with lid.

[0053] Methodology for conducting laboratory analysis and approximate fire tests of TANP.

[0054] Samples of TANP batches are tested for prevailing diameter (the nanoscale size of the capsules is determined), activation temperature, and fire extinguishing efficiency, with the results subsequently recorded in a process chart, which allows for monitoring and identifying deviations and defects during the TANP production stage.

[0055] Determining the outer diameter of TANP capsules consists of two stages. The first stage involves using an electron microscope with a camera connected to a computer running software for automatic capsule sizing. For this purpose, capsule samples are randomly selected from the batch and placed on a microscope slide. The slide is then mounted on the microscope, followed by photographic recording and capsule sizing using software. In the second stage, after determining the TANP capsule sizes, a laboratory sieve with the appropriate mesh size is selected and the batch samples are sifted to sort and determine the predominant sizes within the batch.

[0056] Determining the temperature at which the shell wall of TANP capsules opens. Samples weighing at least 10 g are randomly selected from a batch of TANP capsules. The samples are placed in a thermogravimeter (thermogravimetric analyzer, thermal dilatometer) to monitor changes in capsule volume under temperature exposure, thereby determining the activation temperature.

[0057] Approximate fire tests. There are no specific requirements for fire testing of TANP capsules as a standalone product. Therefore, it is recommended to conduct tests on model fires in accordance with the requirements set forth in GOST R 56459-2015, "Autonomous Fire Extinguishing Devices Using Heat-Activated Microencapsulated Gas-Emitting Fire Extinguishing Agents. General Technical Requirements. Test Methods." Samples weighing at least 1 g are selected randomly from batches of TANP capsules. The samples are weighed and visually assessed for quality and uniformity of appearance. A saucer containing a sample of TANP capsules is attached to the top of a test cabinet with a door. A model fire source selected from GOST R 56459-2015 is placed on the bottom of the cabinet, and ignition is initiated using an ignition source. After the recommended free-burn time has elapsed, the cabinet door is closed. The fire extinguishing time is recorded.The tests are considered successfully passed if the TANP capsule sample successfully extinguishes the selected model fire source.

[0058] INDUSTRIAL APPLICABILITY

[0059] The results of bench tests confirm the achievement of a technical result in the creation of thermally activated fire-extinguishing nanocapsules for preventing the occurrence of flaming combustion and extinguishing fires.

[0060] Stand No. 1 (Table 1).

[0061] Results of nine tests of nanocapsules deposited on a plate.

[0062] The source of combustion is the flame of a candle.

[0063] The selected samples extinguished the model fires. No re-ignitions occurred after extinguishment. The more nanocapsules on the test sample, the faster the extinguishing process. For a plastic electrical distribution box corresponding to Stand No. 1, 0.50 grams of nanocapsules applied to the plate is sufficient.

[0064] Table 1

[0065]

[0066] Stand No. 2 (Table 2)

[0067] Results of eighteen tests of nanocapsules deposited on a plate.

[0068] The source of combustion is the flame of a match.

[0069] The selected samples extinguished the model fires. No re-ignitions occurred after extinguishment. The more nanocapsules on the test sample, the faster the extinguishing process. For a plastic electrical distribution box corresponding to test stand #2, 0.50 grams of nanocapsules applied to the plate is sufficient.

[0070] Table 2

[0071]

[0072] Stand No. 3 (Table 3).

[0073] Results of six tests of nanocapsules deposited on a plate.

[0074] The source of combustion is the flame of a candle.

[0075] The selected samples extinguished the model fires. No re-ignitions occurred after extinguishment. The more nanocapsules in the test sample, the faster the extinguishing process.

[0076] For an electrical panel corresponding to stand No. 3, there must be at least 1 gram of nanocapsules on one plate.

[0077] Table 3

[0078]

[0079] Stand No. 4 (Table 4).

[0080] Results of nine tests of nanocapsules deposited on a plate.

[0081] The combustion source is a flame from a polyethylene plate. The selected samples extinguished the model fires. No re-ignitions occurred after extinguishment. The more nanocapsules on the test sample, the faster the extinguishing process.

[0082] For ventilated volumes corresponding to stand No. 4, 0.50 g of nanocapsules applied to the plate is sufficient.

[0083] Table 4

[0084]

Claims

CLAUSES OF THE INVENTION 1. A thermally activated fire extinguishing nanocapsule comprising a core of fire extinguishing agent encapsulated in a hardened inner shell made from a polyvinyl alcohol aqueous solution, protected by a hardened reinforcing outer shell made from urea, ammonium chloride, resorcinol and formalin, in percentage of the total mass: core (25-30); inner shell (65-55); outer shell (10-15).

2. A thermally activated fire extinguishing nanocapsule according to paragraph 1, characterized in that the fire extinguishing agent used is perfluoroketone DY-F1230 or 1, 1,2, 2, 3,3,4-heptafluorocyclopentane or a combination thereof in equal proportions.

3. A thermally activated fire extinguishing nanocapsule according to paragraph 1, characterized in that its size is 250-950 nm.

4. A thermally activated fire extinguishing nanocapsule according to claim 1, characterized in that the hardened inner shell is obtained from a solution of grade 16 / 1 polyvinyl alcohol and water.

5. A thermally activated fire extinguishing nanocapsule according to claim 1, characterized in that the hardened outer shell is obtained from a dry mixture of urea, ammonium chloride and resorcinol or a mixture thereof, dissolved in water.

6. A method for producing thermally activated fire-extinguishing nanocapsules, according to which a fire-extinguishing agent is added to a polyvinyl alcohol aqueous solution, the fire-extinguishing agent is dispersed in the polyvinyl alcohol aqueous solution until a nanoemulsion is formed, a mixture of urea, ammonium chloride and resorcinol is added, followed by mixing, coacervation and coalescence, then: a) heat the nanoemulsion, add formalin and mix; b) increase the temperature of the nanoemulsion and stir, after which the stirring process is stopped until a precipitate forms in the form of formed nanocapsules, and they are washed; c) nanocapsules are filled with water to a volume greater than the volume of the capsules, followed by heating the resulting mixture with constant stirring; d) formalin is added to the mixture of nanocapsules and water and the temperature is increased; d) every hour, the temperature of the mixture of nanocapsules with water is increased with constant stirring, and after 18-20 hours, the process is stopped for cooling and precipitation in the form of hardened nanocapsules containing a core of fire extinguishing agent encapsulated in a hardened inner shell protected by a hardened reinforcing outer shell.

7. The method according to paragraph 6, characterized in that in order to obtain a nanoemulsion, a fire extinguishing agent is added to a polyvinyl alcohol aqueous solution and dispersed at a temperature of 30-35 °C for 10 minutes while the asynchronous motor is operating at 1000-1500 rpm.

8. The method according to paragraph 6, characterized in that a dry mixture of urea, ammonium chloride and resorcinol or a mixture thereof dissolved in water is added to the nanoemulsion and stirred at a temperature of 30-35 °C for 60 minutes while the asynchronous motor is operating at 300-400 rpm.

9. The method according to paragraph 6, characterized in that in stage a) the nanoemulsion is heated to a temperature of 35-40°C, formalin containing less than 37-41% by weight of formaldehyde is added and stirred for 2 hours, after which the temperature is increased to 45-480°C and stirred for 3-4 hours.

10. The method according to paragraph 6, characterized in that when the asynchronous motor is operating in the 300-400 rpm mode, the temperature is gradually increased from 30-350C: at stage b) to 500C, at stage c) to 400C, at stage d) to 75-800C.

11. The method according to paragraph 6, characterized in that at step c), 8% of formalin, based on the mass of the nanocapsules, is added to the mixture of nanocapsules and water.

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