A dry fire extinguishing material modified by tricobalt tetroxide and a preparation method thereof

Abstract

This invention discloses a dry-water fire extinguishing material and its preparation method with catalytic absorption function of toxic and harmful gases, belonging to the technical field of fire extinguishing materials. This modified dry-water uses deionized water as the core, supplemented with thickeners and flame retardants to modify the core, and hydrophobic nano-silica as the base shell. High-purity (50-100 nm) strongly hydrophobic cobalt tetroxide, modified with silane hydrophobicity, is uniformly loaded onto the shell surface to construct a composite coating structure. This invention utilizes the excellent catalytic activity and thermal stability of cobalt tetroxide, enabling the modified dry-water to maintain excellent fire extinguishing effects while adding the ability to absorb toxic fumes such as carbon monoxide, significantly reducing casualties caused by toxic fumes in fires. This material exhibits excellent hydrophobicity, flowability, and heat resistance, with a complete core-shell structure that prevents leakage. It can extinguish various fires, including those involving deep-seated solids, oils, lithium battery thermal runaway, and confined wells. The formulation and process are simple and environmentally friendly, with broad prospects for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of public safety fire protection materials technology, specifically relating to a hydrophobic cobalt tetroxide modified dry water fire extinguishing material and its preparation method. Background Technology

[0002] Dry water is a core-shell structured powder material prepared using a high-speed shearing process, with hydrophobic nanoparticles as the shell and an aqueous solution as the core. This material possesses high water content, large specific surface area, and rapid heat absorption and cooling capabilities, while also exhibiting excellent powder flowability, low injection pressure requirements, minimal water stain pollution, and good environmental friendliness. As a novel water-based fire extinguishing medium, it has extremely high application value and industrialization potential. Compared to traditional water mist and dry powder fire extinguishing agents, dry water combines the operational advantages of dry powder (easy transport and diffusion) with the inherent strong cooling and fire extinguishing performance of aqueous media. It can be widely adapted to fire prevention and control needs in various complex scenarios such as enclosed spaces, electrical facilities, warehouses, and data centers, and is currently a cutting-edge research hotspot in the field of fire extinguishing materials.

[0003] Existing dry water fire extinguishing materials have the following shortcomings:

[0004] Patent CN101309860B discloses a dry liquid material and its preparation technology. This method uses hydrophobic silica and water as raw materials, and prepares the dry water material through a high-speed stirring process. This system uses only hydrophobic silica as the outer shell coating layer of a core-shell structure, and its fire extinguishing and explosion suppression effects mainly rely on the physical heat absorption and cooling of the core moisture. This type of dry water material mainly relies on two effects for fire extinguishing: rapid cooling and the reduction of instantaneous oxygen concentration by water vapor. Its fire extinguishing and explosion suppression mechanism is singular, lacking the ability to absorb toxic fumes, and its adaptability to various scenarios is significantly limited.

[0005] Patent CN102058951B discloses a preparation technology for a dry-water fire extinguishing agent. This technology introduces inorganic salt functional components into the core aqueous solution, endowing the dry-water material with the ability to inhibit the combustion chain reaction, thus improving the material's fire extinguishing efficiency to a certain extent. However, the dry-water material prepared by this method still suffers from insufficient water retention and poor structural stability. Under long-term storage conditions, internal moisture easily evaporates and permeates through the hydrophobic outer shell, and the condensation of gaseous moisture causes powder agglomeration. At the same time, the water content of the core decreases, directly leading to a continuous decline in the material's fire extinguishing performance. This material, in addition to its cooling and fire extinguishing function, also has the function of interrupting the chain reaction; however, it lacks the ability to absorb toxic gases such as CO.

[0006] Patent CN112206457B proposes a biomass gel-based dry water powder fire extinguishing agent. By adding 0.5–2 wt% of a gelling agent to the system, the water retention and pressure resistance of the dry water material are effectively improved, and the stable storage period at room temperature is extended. The fire extinguishing mechanism of this material is mainly based on the cooling effect, and it does not have the ability to interrupt the chain reaction or absorb toxic fumes such as CO.

[0007] Patent CN115970218A discloses a preparation process for multi-layer hydrophobic coated dry water materials. This method, through a combination of multiple freezing treatments and multi-step stirring and coating, successfully constructs a double-layer hydrophobic outer shell structure, effectively solving the technical problems of dry water materials being prone to clumping and shell structure damage in cold environments, and significantly improving the low-temperature storage stability of the dry water material. The fire extinguishing mechanism of this material is mainly based on rapid cooling and interrupting the chain reaction; it does not have the function of absorbing toxic and harmful fumes such as CO.

[0008] Patent CN118873891A discloses a modified dry-water fire extinguishing and explosion-suppressing material and its preparation process. This method effectively enhances the material's explosion suppression efficiency and combustion chain reaction blocking flame-retardant performance through a two-phase synergistic modification path, introducing ionic liquid functional components into the core aqueous phase and compounding flame-retardant powders into the outer shell layer. Simultaneously, it significantly improves the fire extinguishing and explosion-suppressing efficiency and water retention stability of the dry-water material. The fire extinguishing mechanism of this material is mainly based on rapid cooling and interrupting the chain reaction; it does not have the function of absorbing toxic fumes such as CO.

[0009] In summary, the aforementioned existing dry water fire extinguishing materials technologies, although employing modification methods such as single hydrophobic silica coating, addition of inorganic salts to the aqueous phase, introduction of gel components, construction of multi-layer hydrophobic shells, and compounding of ionic liquids and flame-retardant powders, rely solely on the physical endothermic cooling of the aqueous phase and the interruption of the combustion chain reaction by chemical components to achieve fire extinguishing efficiency; however, none of them introduce hydrophobic cobalt tetroxide functional components into the shell layer, and generally lack the ability to physically adsorb and catalytically degrade toxic smoke from fires, exhibiting inherent shortcomings in smoke disinfection and purification, shell structure density, and long-term water retention stability.

[0010] In fire accidents, over 85% of deaths are caused by toxic and harmful smoke gases, with CO being the most lethal gas in fire smoke. This invention addresses the shortcomings of existing dry-water extinguishing materials that cannot absorb toxic and harmful gases. It innovatively employs hydrophobic nano-cobalt tetroxide to composite-modify the dry-water system, overcoming the limitations of traditional dry-water extinguishing methods that rely solely on physical heat absorption and cooling. This invention constructs a multi-faceted extinguishing mechanism that synergistically integrates rapid heat absorption and cooling of the water phase, catalytically inhibits the combustion chain reaction, and adsorbs and degrades toxic smoke gases. While retaining the excellent heat absorption and cooling properties of dry-water extinguishing materials, the superior catalytic activity of cobalt tetroxide efficiently captures combustion free radicals, interrupting the combustion chain reaction, effectively blocking heat conduction and flame spread, significantly improving the extinguishing rate and enhancing the material's resistance to reignition. Simultaneously, it incorporates anti-caking agents such as hydrogen-containing silicone oil to synergistically optimize the hydrophobic properties and anti-agglomeration ability of the composite shell. The equipment used is universal and readily available, the process is simple, the operation is convenient, and the preparation cost is low. Cobalt tetroxide exhibits both physical adsorption and catalytic degradation effects on typical toxic and harmful smoke gases in fire scenes. It can effectively adsorb and catalytically degrade harmful gas components such as carbon monoxide, nitrogen oxides, and volatile organic pollutants in fire smoke. The abundant porous structure on the surface of cobalt tetroxide can enrich smoke dust and toxic gas molecules through physical action. Its excellent low-temperature catalytic oxidation performance can catalytically convert harmful components such as carbon monoxide and volatile organic compounds into non-toxic and harmless substances such as carbon dioxide and nitrogen in the low-temperature environment of the fire scene. At the same time, it fixes carbon soot particles, inhibits the diffusion and secondary emission of toxic smoke, and weakens the toxicity and light-blocking hazards of the fire scene. Compared with traditional dry water materials, this invention, while maintaining high-efficiency fire extinguishing performance, makes up for the shortcomings of existing dry water materials that only extinguish fire and cannot absorb toxic and harmful smoke. It achieves multiple effects of smoke reduction, detoxification, and hazard suppression while rapidly controlling fire and cooling down, effectively expanding the applicable working conditions and application scenarios of dry water fire extinguishing materials. Summary of the Invention

[0011] The purpose of this invention is to provide a hydrophobic cobalt tetroxide-modified dry-water fire extinguishing material and its preparation method. This invention aims to solve the technical problems of traditional dry-water fire extinguishing materials, such as a single mechanism of action, limited flame retardant and explosion suppression capabilities, lack of toxic smoke purification function, poor anti-reignition effect, insufficient shell density and long-term water retention stability, as well as the cumbersome preparation process, reliance on specialized equipment, and high mass production threshold. This invention introduces hydrophobic nano-cobalt tetroxide to construct a composite functional coating shell, combined with hydrogen-containing silicone oil to synergistically optimize the hydrophobicity and anti-agglomeration properties of the powder surface. This allows the modified dry-water material to retain the inherent advantage of rapid heat absorption and cooling of the core aqueous phase, while also endowing the material with the additional functions of catalytically blocking combustion chain reactions and adsorbing and catalytically degrading toxic smoke in the fire scene, significantly improving the fire extinguishing rate and anti-reignition level. Hydrophobic cobalt tetroxide has a large specific surface area and abundant surface active sites, which can efficiently adsorb and catalytically decompose harmful components such as carbon monoxide, nitrogen oxides, volatile organic pollutants, and soot particles in fire smoke, achieving the effects of smoke reduction and detoxification, and reducing secondary hazards in the fire scene. This invention simplifies the preparation process, allowing for molding through a single-step, short-duration, high-speed mixing process using conventional stirring equipment. Even household blenders can meet the preparation requirements, significantly reducing equipment investment and production costs. The resulting modified dry water possesses comprehensive advantages, including intact core-shell coating, excellent powder flowability, resistance to clumping during long-term storage, rapid fire extinguishing effect, strong resistance to reignition, and smoke purification function. It can meet the needs of various locations for efficient, stable, and convenient fire prevention and control applications.

[0012] To achieve its objectives, the present invention employs the following technical solution:

[0013] This invention provides a hydrophobic cobalt tetroxide-modified dry water fire extinguishing material and its preparation method, comprising the following steps:

[0014] 1) Hydrophobic grafting modification of nano-cobalt tetroxide: A silane coupling agent is added to an ethanol-water mixed solution, wherein the volume ratio of ethanol to water in the mixed solution is (1~3):1; the pH value of the system is adjusted to 4~5, and the mixture is stirred at room temperature for 10~30 min to complete the pre-hydrolysis of the silane coupling agent. Nano-cobalt tetroxide powder is dispersed in ethanol to prepare a cobalt tetroxide suspension; the pre-hydrolyzed silane coupling agent solution is added to the cobalt tetroxide suspension, and after stirring evenly, the system is heated to 60~80℃ and refluxed for 2~4 h to complete the grafting modification; after the reaction, the obtained product is washed with anhydrous ethanol, and then vacuum dried at 80~100℃ to obtain the hydrophobically modified cobalt tetroxide product;

[0015] 2) The raw materials are formulated in the following percentages by mass: hydrophobic cobalt tetroxide 3.50%~6.00%, hydrophobic fumed silica 6.00%~11.00%, anti-caking agent 0.90%~1.40%, purified water 80.00%~90.00%, thickener 0.12%~0.20%, and flame retardant 1.20%~1.80%;

[0016] 3) Add the thickener and flame retardant to pure water and mix thoroughly at 300~400r / min until homogeneous to obtain a composite liquid phase base solution;

[0017] 4) Mix hydrophobic cobalt tetroxide and hydrophobic fumed silica and stir thoroughly at 300~400 r / min until the powder is dispersed and uniformly mixed to obtain composite solid powder;

[0018] 5) Slowly inject the prepared composite liquid base solution into the composite hydrophobic solid powder along the inner wall of the container, and simultaneously add the weighed anti-caking agent; use a high-speed wall-breaking shearing device with the equipment speed set to 20,000~30,000 r / min, and continuously shear for 5~8s, and prepare a core-shell structured cobalt tetroxide modified dry water fire extinguishing material by high-speed shearing and coating.

[0019] Furthermore, the hydrophobic cobalt tetroxide in the raw material components has a particle size of 50-100 nm, a specific surface area of ​​25-45 m² / g, and a water contact angle of 130°-155°, which can form a dry water shell with the hydrophobic fumed silica. The hydrophobic cobalt tetroxide is a nano-sized particle, and its addition can form a good synergistic combination with fumed silica in the shell structure, filling the gaps in the hydrophobic silica network and constructing a denser and more stable composite coating layer, effectively isolating heat transfer and preventing the infiltration of outside air; at the same time, it has a synergistic effect with the core moisture and flame-retardant components, significantly improving the flame-retardant and explosion-suppressing performance of the system. With its high specific surface area and surface active sites, it adsorbs and catalytically degrades carbon monoxide, soot, and volatile toxic smoke components in the fire scene, possessing both fire extinguishing and explosion-suppressing and smoke-reducing and detoxifying effects.

[0020] Furthermore, the thickener in the raw material components is one or more of xanthan gum, sodium polyacrylate, and hydroxypropyl methylcellulose. The addition of the thickener can increase the viscosity of the aqueous phase, improve the dispersibility of the components, and enhance the toughness of the coating film.

[0021] Furthermore, the anti-caking agent in the raw material components is one or more of high-hydrogen silicone oil and mica powder. The addition of the anti-caking agent can effectively prevent the dry water material from clumping, ensuring the fire extinguishing and explosion suppression efficiency of the dry water material during use.

[0022] Furthermore, the flame retardant in the raw material components is one or more of urea, ammonium polyphosphate, and ammonium dihydrogen phosphate. These materials are easily decomposed by heat, releasing inert gases (such as ammonia, carbon dioxide, and water vapor), which can break the chain reaction. After some of the flame retardants decompose, they form a dense, heat-insulating carbon layer, blocking the transfer of heat and oxygen.

[0023] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0024] (1) Strong compatibility with hydrophobic silica-based dry water systems and significant functional synergistic effect. The addition of nano-hydrophobic cobalt tetroxide significantly improves the overall fire prevention and control performance of the material. In the fire scene, it can efficiently capture free radicals of combustion chain reaction with its excellent low-temperature catalytic activity. At the same time, it forms a synergistic effect with the rapid endothermic cooling of the water phase, and strongly blocks the combustion transmission process. Compared with traditional technology, the high specific surface area and abundant surface active sites of cobalt tetroxide can efficiently adsorb and catalytically degrade toxic and harmful smoke components such as carbon monoxide, nitrogen oxides, volatile organic pollutants and soot particles generated by combustion, reduce smoke toxicity and smoke density, and significantly improve visibility in the fire scene. The addition of cobalt tetroxide can effectively reduce the amount of additional flame retardant additives added to the system and avoid the negative impact of additives on the stability of water-containing cores. In addition, the active sites on the surface of cobalt tetroxide can catalytically transform the adsorbed toxic fumes and inhibit the secondary release of harmful components, achieving the dual effects of fire suppression and smoke reduction and detoxification while extinguishing and controlling fire. This invention significantly enhances the fire extinguishing and explosion suppression performance of dry water materials, makes up for the shortcomings of traditional dry water materials without smoke purification function, and broadens its application range in complex fire scenarios such as enclosed spaces, underground places, and data centers.

[0025] (2) Combined with hydrogen-containing silicone oil, the hydrophobicity of the powder surface is optimized, effectively reducing the van der Waals forces between particles, reducing the phenomenon of moisture absorption, agglomeration and caking during long-term storage, and significantly improving the powder flowability and spraying performance; a low dose of phase stabilizing agent can be added to the aqueous core, which can improve the stability of the water-containing core during shear preparation and long-term storage without affecting the rapid evaporation and heat absorption performance of the aqueous phase, and avoid demulsification and water seepage.

[0026] (3) It is compatible with household blenders or industrial high-speed mixers, with no premixing, freezing, or recycling processes, resulting in high preparation efficiency;

[0027] (4) This system retains the core advantage of rapid heat absorption and cooling of the aqueous phase of dry water materials. At the same time, the ability to block the combustion chain reaction can be further enhanced by adding flame retardant additives (such as urea and inorganic salts) to the core. This system has good fire control and anti-reignition effects for Class A solid fires, Class B liquid fires and Class E electrical fires. While maintaining rapid fire extinguishing capability, it makes up for the shortcomings of traditional dry water materials in preventing secondary smoke hazards in complex scenarios such as enclosed spaces and underground places. The comprehensive application value is significantly improved. Attached Figure Description

[0028] Figure 1 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0029] To further illustrate the present invention, the hydrophobic cobalt tetroxide-modified dry water fire extinguishing material provided by the present invention is described below with reference to embodiments. The described embodiments are not intended to limit the scope of protection of the present invention, and the implementation of the present invention is not limited thereto.

[0030] Example 1

[0031] In this embodiment, the thickener used is hydroxypropyl methylcellulose, the flame retardant is urea, and the anti-caking agent is high-hydrogen silicone oil. The raw materials, by mass ratio, are: 86.78% purified water, 1.50% urea, 0.15% hydroxypropyl methylcellulose, 1.07% high-hydrogen silicone oil, 7.00% hydrophobic fumed silica, and 3.50% hydrophobic cobalt tetroxide. The hydrophobic cobalt tetroxide is prepared in-house, and its preparation method and the method for preparing it by drying are as follows:

[0032] (1) Preparation of hydrophobically modified cobalt tetroxide

[0033] 1) Add the silane coupling agent to an ethanol-water mixed solution, wherein the volume ratio of ethanol to water in the mixed solution is 2:1; adjust the pH of the system to 4.5 with dilute acetic acid, and stir magnetically for 20 minutes at room temperature to complete the pre-hydrolysis of the silane coupling agent;

[0034] 2) Disperse the cobalt tetroxide powder obtained in step 1) in anhydrous ethanol and ultrasonically disperse for 10 min to obtain a uniform suspension; add the pre-hydrolyzed silane coupling agent solution to the suspension, stir evenly, heat to 70℃, and reflux for 3 h to complete the grafting modification.

[0035] 3) After the reaction was completed, the product was filtered and washed three times with anhydrous ethanol to remove the ungrafted coupling agent. Then it was vacuum dried at 90°C for 12 h to obtain hydrophobically modified cobalt tetroxide powder. The contact angle between the powder and water was 142°.

[0036] (2) Preparation of dry water extinguishing materials

[0037] 1) Mix hydrophobic cobalt tetroxide and hydrophobic fumed silica and stir thoroughly at 350 r / min until the powder is dispersed and uniformly mixed to obtain a mixed powder;

[0038] 2) Stir urea, hydroxypropyl methylcellulose, and purified water at 350 rpm until they are thoroughly mixed to obtain a mixed solution;

[0039] 3) Pour the mixed solution into the mixed fraction, add high-hydrogen silicone oil, and place it in a mixer and stir at 22000r / min for 5~8s to obtain core-shell structured dry water particles containing a hydrophobic outer shell and a water-containing inner core.

[0040] Example 2

[0041] In this embodiment, the thickener used is hydroxypropyl methylcellulose, the flame retardant is urea, and the anti-caking agent is high-hydrogen silicone oil. The raw materials, by mass ratio, are: 83.81% purified water, 1.60% urea, 0.14% hydroxypropyl methylcellulose, 1.20% high-hydrogen silicone oil, 8.50% hydrophobic fumed silica, and 4.75% hydrophobic cobalt tetroxide. The hydrophobic cobalt tetroxide is prepared in-house, and its preparation method and the method for preparing it by drying are as follows:

[0042] (1) Preparation of hydrophobically modified cobalt tetroxide

[0043] 1) Add the silane coupling agent to an ethanol-water mixed solution, wherein the volume ratio of ethanol to water in the mixed solution is 2:1; adjust the pH of the system to 4.5 with dilute acetic acid, and stir magnetically for 20 minutes at room temperature to complete the pre-hydrolysis of the silane coupling agent;

[0044] 2) Disperse the cobalt tetroxide powder obtained in step 1) in anhydrous ethanol and ultrasonically disperse for 10 min to obtain a uniform suspension; add the pre-hydrolyzed silane coupling agent solution to the suspension, stir evenly, heat to 70℃, and reflux for 3 h to complete the grafting modification.

[0045] 3) After the reaction was completed, the product was filtered and washed three times with anhydrous ethanol to remove the ungrafted coupling agent. Then it was vacuum dried at 90°C for 12 h to obtain hydrophobically modified cobalt tetroxide powder. The contact angle between the powder and water was 142°.

[0046] (2) Preparation of dry water extinguishing materials

[0047] 1) Mix hydrophobic cobalt tetroxide and hydrophobic fumed silica and stir thoroughly at 350 r / min until the powder is dispersed and uniformly mixed to obtain a mixed powder;

[0048] 2) Stir urea, hydroxypropyl methylcellulose, and purified water at 350 rpm until homogeneous to obtain a mixed solution;

[0049] 3) Pour the mixed solution into the mixed component, add high-hydrogen silicone oil, and place it in a mixer and stir at 22000r / min for 5~8s to obtain a core-shell structure dry water containing a hydrophobic outer shell and a water-containing inner core.

[0050] Example 3

[0051] In this embodiment, the thickener used is hydroxypropyl methylcellulose, the flame retardant is urea, and the anti-caking agent is high-hydrogen silicone oil. The raw materials, by mass ratio, are: 81.23% purified water, 1.20% urea, 0.12% hydroxypropyl methylcellulose, 1.40% high-hydrogen silicone oil, 10.00% hydrophobic fumed silica, and 6.00% hydrophobic cobalt tetroxide. The hydrophobic cobalt tetroxide is prepared in-house, and its preparation method and the method for preparing it by drying are as follows:

[0052] (1) Preparation of hydrophobically modified cobalt tetroxide

[0053] 1) Add the silane coupling agent to an ethanol-water mixed solution, wherein the volume ratio of ethanol to water in the mixed solution is 2:1; adjust the pH of the system to 4.5 with dilute acetic acid, and stir magnetically for 20 minutes at room temperature to complete the pre-hydrolysis of the silane coupling agent;

[0054] 2) Disperse the cobalt tetroxide powder obtained in step 1) in anhydrous ethanol and ultrasonically disperse for 10 min to obtain a uniform suspension; add the pre-hydrolyzed silane coupling agent solution to the suspension, stir evenly, heat to 70℃, and reflux for 3 h to complete the grafting modification.

[0055] 3) After the reaction was completed, the product was filtered and washed three times with anhydrous ethanol to remove the ungrafted coupling agent. Then it was vacuum dried at 90°C for 12 h to obtain hydrophobically modified cobalt tetroxide powder. The contact angle between the powder and water was 142°.

[0056] (2) Preparation of dry water extinguishing materials

[0057] 1) Mix hydrophobic cobalt tetroxide and hydrophobic fumed silica and stir thoroughly at 350 r / min until the powder is dispersed and uniformly mixed to obtain a mixed powder;

[0058] 2) Stir urea, hydroxypropyl methylcellulose, and purified water at 350 rpm until homogeneous to obtain a mixed solution;

[0059] 3) Pour the mixed solution into the mixed component, add high-hydrogen silicone oil, and place it in a mixer and stir at 22000r / min for 5~8s to obtain dry water with a core-shell structure containing a hydrophobic outer shell and a water-containing inner core.

[0060] Comparative Example 1

[0061] In this embodiment, hydrophobic cobalt tetroxide is not added. The thickener used is hydroxypropyl methylcellulose, the flame retardant is urea, and the anti-caking agent is high-hydrogen silicone oil. The raw materials, by mass ratio, are: 85.83% pure water, 1.64% urea, 0.14% hydroxypropyl methylcellulose, 0.48% high-hydrogen silicone oil, and 11.91% hydrophobic fumed silica.

[0062] Its preparation method is as follows:

[0063] 1) Pour the weighed hydrophobic fumed silica into a mixer;

[0064] 2) Stir urea, hydroxypropyl methylcellulose, and purified water at 300 rpm until homogeneous to obtain a mixed solution;

[0065] 3) Pour the mixed solution into the mixed fraction, add high-hydrogen silicone oil, and place it in a mixer and stir at 22000r / min for 5~8s to obtain core-shell structured dry water particles containing a hydrophobic outer shell and a water-containing inner core.

[0066] Fire extinguishing performance test: 200 mL of n-heptane was used as fuel and placed in a 120 mm × 80 mm combustion dish. After pre-ignition for 60 seconds, 50 g of the corresponding group of fire extinguishing material was added, and the extinguishing time was recorded. The test was performed in triplicate and the average value was taken. The measured values ​​are shown in Table 1.

[0067] Reignition resistance test: After fire extinguishing, observe continuously for 10 minutes and record the material's reignition time. If there is no reignition within 10 minutes, it is judged as no reignition. Perform three parallel tests and take the average value. The measured values ​​are shown in Table 1.

[0068] Determination of harmful gas adsorption and catalytic performance: A 1m³ sealed test chamber was used to simulate the smoke environment of a fire scene. After the corresponding group of materials were introduced, the CO and NO concentrations were recorded within 10 minutes. x Concentration changes were analyzed to calculate the removal rate. Simultaneously, a fixed-bed microcatalytic reactor was used to measure the CO catalytic conversion rate at 200℃ (intermediate temperature range in the fire zone), with three parallel measurements taken and the average value recorded. The measured values ​​are shown in Table 1.

[0069] Catalytic performance was specifically tested using a fixed-bed microcatalytic reactor with 1% CO and air as the reactants. The total flow rate was 50 mL / min, and the heating rate was 5℃ / min. The CO catalytic conversion rate at 200℃ was measured and used as the core indicator for judging the catalytic effect. The measured values ​​are shown in Table 1.

[0070] Table 1 Results of Adsorption and Catalytic Performance Tests for Harmful Gases Example 1 28±1.2 Reignition occurred after 7.2 minutes. <![CDATA[CO:62.3、NO x :58.7]]> 48.5 Example 2 24±0.9 Reignition occurred after 9.5 minutes. <![CDATA[CO:68.5、NO x :64.2]]> 62.3 Example 3 22±0.7 No reignition was observed within a 10-minute observation period. <![CDATA[CO:73.1、NO x :69.5]]> 75.8 Comparative Example 1 30±1.5 Reignition occurred after 7 minutes <![CDATA[CO:0、NO x :0]]> 0 (No catalytic activity)

[0071] The data above shows that adding hydrophobic cobalt tetroxide to the solid shell can effectively improve the fire extinguishing efficiency of dry water, the resistance to reignition, and the absorption and purification rate of toxic and harmful gases.

[0072] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cobalt tetroxide-modified dry water fire extinguishing material and its preparation method, characterized in that, Includes the following steps: 1) Hydrophobic grafting modification of nano-cobalt tetroxide: Silane coupling agent is added to an ethanol-water mixed solution, wherein the volume ratio of ethanol to water in the mixed solution is (1~3):1; the pH value of the system is adjusted to 4~5, and the mixture is stirred at room temperature for 10~30 min to complete the pre-hydrolysis of the silane coupling agent. Nano-cobalt tetroxide powder is dispersed in ethanol to prepare a cobalt tetroxide suspension; the pre-hydrolyzed silane coupling agent solution is added to the cobalt tetroxide suspension, and after stirring evenly, the system is heated to 60~80℃ and refluxed for 2~4 h to complete the grafting modification; after the reaction, the obtained product is washed with anhydrous ethanol, and then vacuum dried at 80~100℃ to obtain the hydrophobically modified cobalt tetroxide product; 2) The raw materials are formulated in the following percentages by mass: hydrophobic cobalt tetroxide 3.50%~6.00%, hydrophobic fumed silica 6.00%~11.00%, anti-caking agent 0.90%~1.40%, purified water 80.00%~90.00%, thickener 0.12%~0.20%, and flame retardant 1.20%~1.80%; 3) Add the weighed thickener and flame retardant to 200ml of pure water, set the stirring speed to 300~400r / min and stir continuously at low speed until the materials are completely wetted, dissolved and dispersed to obtain a composite liquid phase base solution with uniform components. 4) Mix hydrophobic cobalt tetroxide with hydrophobic fumed silica and stir at a constant speed of 300~400 r / min until the powder is fully mixed without stratification or agglomeration, to obtain a uniform composite hydrophobic solid powder. 5) Slowly inject the prepared composite liquid base solution into the composite hydrophobic solid powder along the inner wall of the container, and simultaneously add the weighed anti-caking agent; use a high-speed mixer shearing device, set the mixer speed to 20000~30000r / min, and continuously shear for 5~8s, and prepare the core-shell structured cobalt tetroxide modified dry water fire extinguishing material by high-speed shearing and coating.

2. The production method according to claim 1, characterized by, The hydrophobic cobalt tetroxide in the raw material component has a particle size of 50~100nm and a water contact angle of 130°~155°. The hydrophobic cobalt tetroxide is obtained by co-precipitation of cobalt nitrate hexahydrate solution or cobalt chloride solution with ammonia solution. The pH of the system is controlled at 9~10, and the system is aged at a constant temperature. After washing, drying and calcination at 400~450℃, cobalt tetroxide powder is obtained. After pre-hydrolyzing the silane coupling agent in an alcohol-water solution, it was mixed with cobalt tetroxide in suspension, refluxed at 60-80℃ for grafting modification, and then washed and dried to obtain hydrophobically modified cobalt tetroxide.

3. The preparation method according to claim 1, characterized in that, The hydrophobic fumed silica laser particles in the raw material composition have a particle size ≤15μm, a dispersion ≤2, and a BET specific surface area of ​​260±20m². 2 / g, carbon content 2.5~4.0wt%, methanol value 55~65vol.%, water contact angle 120°~145°, all raw materials are pre-screened to remove large particles and impurities.

4. The production method according to claim 1, characterized by, The thickener mentioned in the raw material components is one or more of xanthan gum, sodium polyacrylate and hydroxypropyl methylcellulose.

5. The method of claim 1, wherein, The anti-caking agent mentioned in the raw material components is one of high-hydrogen silicone oil and mica powder.

6. The method of claim 1, wherein, The flame retardant in the raw material components is one or more of urea, ammonium polyphosphate, and ammonium dihydrogen phosphate.

7. A hydrophobic cobalt tetroxide modified dry water fire extinguishing material prepared by the preparation method according to any one of claims 1 to 6.

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