Fire extinguishing microcapsules and methods of making

Abstract

The application discloses a fire-extinguishing microcapsule and a preparation method thereof, and belongs to the technical field of fire extinguishing. The fire-extinguishing microcapsule comprises a capsule core and a capsule shell, the capsule core comprises a water-based fire extinguishing agent and a fluorine-based fire extinguishing agent which are not mutually soluble, and the capsule shell is wrapped outside the capsule core; wherein the mass ratio of the water-based fire extinguishing agent to the fluorine-based fire extinguishing agent is K1, and K1 satisfies 0.5 <= K1 <= 2. The fluorine-based fire extinguishing agent is preferentially vaporized to break the capsule shell and be released due to the characteristics of low boiling point and high vapor pressure, so as to quickly block the chain reaction of combustion, the water-based fire extinguishing agent is then expanded and secondarily released by heat, continuously reduces the temperature by vaporization and heat absorption, and the overall fire extinguishing efficiency of the fire-extinguishing microcapsule is improved by using the physical property difference between the two.

Description

Technical Field

[0001] This application belongs to the field of fire extinguishing technology, and in particular relates to a fire extinguishing microcapsule and its preparation method. Background Technology

[0002] Fire extinguishing microcapsules are smart fire extinguishing materials that encapsulate extinguishing agents within tiny polymer capsules. They release the extinguishing agent upon external stimuli (such as heat, pressure, or chemical triggering), achieving precise and efficient fire suppression. However, currently, fluorinated extinguishing agents are often used as the core of these microcapsules. These agents primarily inhibit the combustion chain reaction through chemical blocking, specifically by capturing highly reactive free radicals in the flame in the gas phase to interrupt the chain reaction process. While this method is relatively efficient in suppressing flame propagation, fluorinated extinguishing agents have a low specific heat capacity and weak vaporization endothermic capacity. Upon contact with a fire source, they struggle to rapidly reduce the fuel surface temperature and effectively absorb large amounts of heat, resulting in poor cooling effects on deep fires or continuously burning solid combustibles, thus impacting the fire extinguishing effectiveness. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the related art. To this end, this application proposes a fire extinguishing microcapsule and its preparation method, which utilizes the synergistic effect of water-based fire extinguishing agents and fluorine-based fire extinguishing agents to achieve a dual "physical + chemical" fire extinguishing mechanism, thereby maximizing the fire extinguishing effect.

[0004] In a first aspect, this application provides a fire extinguishing microcapsule, comprising:

[0005] The core of the fire extinguishing agent comprises immiscible water-based fire extinguishing agent and fluorine-based fire extinguishing agent;

[0006] A capsule shell, which covers the core; wherein,

[0007] The mass ratio of the water-based fire extinguishing agent to the fluorine-based fire extinguishing agent is K1, and K1 satisfies: 0.5≤K1≤2.

[0008] According to the fire extinguishing microcapsule of this application, the core comprises an immiscible water-based fire extinguishing agent and a fluorine-based fire extinguishing agent. The water-based fire extinguishing agent typically has good cooling capacity, reducing the temperature of the fire source by absorbing heat, thereby achieving the purpose of physical fire extinguishing. The fluorine-based fire extinguishing agent has good chemical inhibition properties, capable of rapidly interrupting the chemical reaction chain of combustion and preventing the spread of fire. That is, due to its low boiling point and high vapor pressure, the fluorine-based fire extinguishing agent preferentially vaporizes and breaks through the capsule shell to release, rapidly interrupting the chain reaction of combustion. The water-based fire extinguishing agent subsequently expands upon heating and is released a second time, continuously cooling through vaporization and heat absorption. Utilizing the difference in physical properties between the two, a self-driven, staged release is achieved, improving the overall fire extinguishing efficiency of the fire extinguishing microcapsule.

[0009] According to one embodiment of this application, the raw materials for preparing the water-based fire extinguishing agent include one of seawater and an aqueous solution of inorganic salts.

[0010] According to one embodiment of this application, when the raw materials for preparing the water-based fire extinguishing agent include an aqueous solution of inorganic salts, the aqueous solution of inorganic salts includes at least one of potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, potassium chloride, or sodium chloride aqueous solution.

[0011] According to one embodiment of this application, the raw materials for preparing the water-based fire extinguishing agent also include an antifreeze agent.

[0012] According to one embodiment of this application, the raw materials for preparing the water-based fire extinguishing agent further include 0.1% to 5% by mass of a water-based surfactant.

[0013] According to one embodiment of this application, the aqueous surfactant includes at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0014] According to one embodiment of this application, the mass ratio of the shell to the core is K2, and K2 satisfies: 1 / 9 ≤ K2 ≤ 1.

[0015] According to one embodiment of this application, the diameter of the fire extinguishing microcapsule is D, and D satisfies: 100μm≤D≤1000μm.

[0016] According to one embodiment of this application, the raw materials for preparing the fluorinated fire extinguishing agent include perfluorohexanone; and / or

[0017] The raw materials for preparing the capsule include photopolymerizable resin.

[0018] Secondly, this application provides a method for preparing the fire extinguishing microcapsules as described above, comprising:

[0019] Obtain raw materials for preparing the core and shell of the fire extinguishing agent, wherein the core comprises immiscible water-based fire extinguishing agent and fluorine-based fire extinguishing agent;

[0020] The raw materials for preparing the capsule core and the raw materials for preparing the capsule shell are injected into the needle of the microfluidic device, and microdroplets are formed based on coaxial flow or flow focusing technology.

[0021] The microdroplets are subjected to UV curing treatment so that the capsule shell covers the capsule core, thereby obtaining the fire extinguishing microcapsule.

[0022] According to the preparation method of the fire extinguishing microcapsule of this application, the synergistic effect of water-based fire extinguishing agent 210 and fluorine-based fire extinguishing agent 220 is used to achieve a dual fire extinguishing mechanism of "physical + chemical" and improve the fire extinguishing effect as much as possible.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram of the structure of the fire extinguishing microcapsule provided in the embodiments of this application;

[0026] Figure 2 This is a schematic flowchart of the preparation method of the fire extinguishing microcapsules provided in the embodiments of this application.

[0027] Figure label:

[0028] 100. Capsule shell;

[0029] 200. Fire extinguishing agent core; 210. Water-based fire extinguishing agent; 220. Fluorine-based fire extinguishing agent;

[0030] 300. Microfluidic devices. Detailed Implementation

[0031] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0032] The following is for reference. Figure 1 The fire extinguishing microcapsule provided in this application embodiment is described. The fire extinguishing microcapsule includes a core 200 and a shell 100. It should be noted that the shapes of the core 200 and the shell 100 include, but are not limited to, spherical shapes, and this embodiment does not impose specific limitations on them.

[0033] The core 200 comprises immiscible water-based extinguishing agent 210 and fluorine-based extinguishing agent 220; the shell 100 covers the core 200; wherein,

[0034] The mass ratio of water-based fire extinguishing agent 210 to fluorine-based fire extinguishing agent 220 is K1, and K1 satisfies: 0.5≤K1≤2.

[0035] Understandably, the core 200 comprises immiscible water-based extinguishing agent 210 and fluorine-based extinguishing agent 220. Water-based extinguishing agent 210 typically possesses excellent cooling capabilities, absorbing heat to lower the temperature of the fire source, thereby achieving physical fire extinguishing. Fluorine-based extinguishing agent 220 exhibits excellent chemical inhibition, rapidly interrupting the chemical reaction chain of combustion and preventing the spread of fire. Specifically, due to its low boiling point and high vapor pressure, fluorine-based extinguishing agent 220 preferentially vaporizes and breaks through the shell 100 to release, rapidly interrupting the chain reaction of combustion. Water-based extinguishing agent 210 subsequently expands upon heating and is released a second time, continuously cooling through vaporization and heat absorption. Utilizing the difference in physical properties between the two agents achieves a self-driven, staged release, improving the overall fire extinguishing efficiency of the extinguishing microcapsule.

[0036] For example, samples 1-3 were prepared respectively, and samples 1-3 were placed directly above a 24L power distribution cabinet. A 150*100*100 mm n-heptane fuel container was placed directly below the 24L power distribution cabinet. 100 mL of n-heptane fuel was used for each test, and the data obtained are shown in Table 1 below:

[0037] Table 1

[0038]

[0039] The preparation method of sample 1 is as follows:

[0040] A certain amount of sodium chloride, antifreeze, and sodium dodecylbenzenesulfonate are added to an aqueous solution and mixed evenly to obtain the raw materials for preparing water-based fire extinguishing agent 210. Based on the total mass of the raw materials for water-based fire extinguishing agent 210, the raw materials include 5% sodium chloride, 0.5% antifreeze, and 2% sodium dodecylbenzenesulfonate (i.e., by mass parts, the raw materials include: 5 parts sodium chloride, 0.5 parts antifreeze, 2 parts sodium dodecylbenzenesulfonate, and 92.5 parts water).

[0041] A certain amount of epoxy acrylate, polyurethane acrylate, 1,6-hexanediol diacrylate, isoborneol acrylate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and silicone leveling agent are mixed evenly to obtain the raw material for preparing the capsule shell 100. Based on the total mass of the raw material for the capsule shell 100, the raw material includes 55% by mass of epoxy acrylate, 5% by mass of polyurethane acrylate, 22% by mass of 1,6-hexanediol diacrylate, 12% by mass of isoborneol acrylate, 3% by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2.5% by mass of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.5% by mass of silicone leveling agent.

[0042] The raw materials for preparing water-based fire extinguishing agent 210 were injected into the corresponding needles of the microfluidic device using an injection pump. The flow rate of the raw materials for preparing the shell 100 was controlled at 4 mL / h and 2.15 mL / h. A 4% polyvinyl alcohol solution was used as the driving phase with a flow rate of 45 mL / h to obtain microdroplets with a diameter of about 1000 μm.

[0043] The microdroplets are irradiated with UV light so that the capsule shell 100 covers the capsule core 200, thus obtaining fire extinguishing microcapsules;

[0044] The fire extinguishing microcapsules were washed with ethanol and deionized water and then vacuum dried at 35°C.

[0045] The preparation method of sample 2 is as follows;

[0046] Perfluorohexanone was used as a raw material for preparing fluorinated fire extinguishing agent 220;

[0047] A certain amount of epoxy acrylate, polyurethane acrylate, 1,6-hexanediol diacrylate, isoborneol acrylate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and silicone leveling agent are mixed evenly to obtain the raw material for preparing the capsule shell 100. Based on the total mass of the raw material for the capsule shell 100, the raw material includes 55% by mass of epoxy acrylate, 5% by mass of polyurethane acrylate, 22% by mass of 1,6-hexanediol diacrylate, 12% by mass of isoborneol acrylate, 3% by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2.5% by mass of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.5% by mass of silicone leveling agent.

[0048] The raw materials for preparing fluorine-based fire extinguishing agent 220 were injected into the corresponding needles of the microfluidic device using an injection pump. The flow rate of the raw materials for preparing the shell 100 was controlled at 2.5 mL / h and 2.15 mL / h. A 4% polyvinyl alcohol solution was used as the driving phase with a flow rate of 40 mL / h to obtain microdroplets with a diameter of about 1000 μm.

[0049] The microdroplets are irradiated with UV light so that the capsule shell 100 covers the capsule core 200, thus obtaining fire extinguishing microcapsules;

[0050] The fire extinguishing microcapsules were washed with ethanol and deionized water and then vacuum dried at 35°C.

[0051] The preparation method of sample 3 is as follows:

[0052] A certain amount of sodium chloride, antifreeze, and sodium dodecylbenzenesulfonate are added to an aqueous solution and mixed evenly to obtain the raw materials for preparing water-based fire extinguishing agent 210. Based on the total mass of the raw materials for water-based fire extinguishing agent 210, the raw materials include 5% sodium chloride, 0.5% antifreeze, and 2% sodium dodecylbenzenesulfonate (i.e., by mass parts, the raw materials include: 5 parts sodium chloride, 0.5 parts antifreeze, 2 parts sodium dodecylbenzenesulfonate, and 92.5 parts water).

[0053] Perfluorohexanone was used as a raw material for preparing fluorinated fire extinguishing agent 220;

[0054] A certain amount of epoxy acrylate, polyurethane acrylate, 1,6-hexanediol diacrylate, isoborneol acrylate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and silicone leveling agent are mixed evenly to obtain the raw material for preparing the capsule shell 100. Based on the total mass of the raw material for the capsule shell 100, the raw material includes 55% by mass of epoxy acrylate, 5% by mass of polyurethane acrylate, 22% by mass of 1,6-hexanediol diacrylate, 12% by mass of isoborneol acrylate, 3% by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2.5% by mass of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.5% by mass of silicone leveling agent.

[0055] The raw materials for preparing water-based fire extinguishing agent 210 were injected into the corresponding needles of microfluidic device 300 using an injection pump. The flow rate of the raw materials for preparing fluorine-based fire extinguishing agent 220 was controlled at 2 mL / h, the flow rate of the raw materials for preparing shell 100 was controlled at 1.25 mL / h, and the flow rate of the raw materials for preparing shell 100 was controlled at 2.15 mL / h. A 4% polyvinyl alcohol solution was used as the driving phase and its flow rate was 44 mL / h to obtain microdroplets with a diameter of about 1000 μm.

[0056] The microdroplets are irradiated with UV light so that the capsule shell 100 covers the capsule core 200, thus obtaining fire extinguishing microcapsules;

[0057] The fire extinguishing microcapsules were washed with ethanol and deionized water and then vacuum dried at 35°C.

[0058] It should be noted that after igniting the n-heptane fuel with an electronic igniter and closing the cabinet door, the timer is started and the flame extinguishing time is recorded to obtain the initial extinguishing time t. After the flame is extinguished, the cabinet door is opened, and the electronic igniter is used to ignite it again. The current extinguishing time is recorded again. This process is repeated until the flame cannot be extinguished, at which point the number of extinguishing attempts is obtained, and the flame is extinguished with a fire extinguisher.

[0059] Understandably, n-heptane is a flammable liquid with a high combustion rate and flame temperature, making it suitable for simulating liquid fuel fires in real-world fire scenarios. The experiment was conducted inside an electrical distribution cabinet. Timing began after the cabinet door was closed, simulating a fire environment in a relatively enclosed space, which increased the difficulty of extinguishing the fire. This is because flames in an enclosed space may temporarily extinguish due to lack of oxygen, but will reignite once oxygen is restored (by opening the cabinet door). Furthermore, an electronic igniter was used each time to ensure consistent ignition conditions.

[0060] Understandably, as shown in Table 1, Sample 3, compared to Samples 1 and 2, has the shortest initial extinguishing time, indicating its strongest reaction speed and extinguishing ability during the first extinguishing. Sample 3 also has the most extinguishing times, demonstrating its effective extinguishing capabilities even after repeated use, exhibiting good stability and durability. Furthermore, Sample 3 has the shortest average extinguishing time, indicating its outstanding performance across multiple extinguishing cycles, with each extinguishing session lasting only a short time and allowing for repeated use. This suggests that utilizing immiscible water-based extinguishing agent 210 and fluorine-based extinguishing agent 220 can significantly improve extinguishing performance.

[0061] In addition, the mass of fluorinated fire extinguishing agent 220 is 0.5 to 2 times that of water-based fire extinguishing agent 210, which balances the fire extinguishing performance of the two. When the proportion of fluorinated fire extinguishing agent 220 is low, the cooling capacity of the fire extinguishing microcapsules may be relatively strong, but the chemical inhibition effect may be relatively weak; while when the proportion of fluorinated fire extinguishing agent 220 is high, the chemical inhibition effect will be more obvious, but the cooling capacity may be affected to some extent.

[0062] According to the fire extinguishing microcapsules provided in the embodiments of this application, the synergistic effect of water-based fire extinguishing agent 210 and fluorine-based fire extinguishing agent 220 is utilized to achieve a dual fire extinguishing mechanism of "physical + chemical" to improve the fire extinguishing effect as much as possible.

[0063] In some embodiments, the raw materials for preparing the water-based fire extinguishing agent 210 include one of seawater and an aqueous solution of inorganic salts. Of course, in some embodiments, the water-based fire extinguishing agent 210 may include F-500, or F-500 may be added to the aqueous solution of seawater and inorganic salts.

[0064] Understandably, whether seawater or inorganic salt solution is used as the water-based fire extinguishing agent 210, after the capsule 100 is heated and broken, the water-based fire extinguishing agent 210 forms a fine water mist, which vaporizes in the flame and releases free metal ions. This allows the metal ions to react with free radicals and peroxides in the flame, thereby absorbing free radicals in the combustion process, stopping the chain reaction, and inhibiting the combustion process. This effectively improves the fire extinguishing ability and fire extinguishing effect of the fire extinguishing microcapsule.

[0065] In some embodiments, when the raw materials for preparing the water-based fire extinguishing agent 210 include an aqueous solution of inorganic salts, the aqueous solution of inorganic salts includes at least one of potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, potassium chloride, or sodium chloride aqueous solution.

[0066] Understandably, inorganic salts, when dissolved in water, form aqueous solutions with high specific heat capacity, capable of absorbing a large amount of heat and thus lowering the temperature of the fire source. Inorganic salts such as sodium bicarbonate or potassium bicarbonate decompose upon heating, absorbing heat and releasing carbon dioxide, further enhancing the cooling effect. Furthermore, the alkaline salts in aqueous solutions can increase the thermal conductivity of water-based fire extinguishing agents, allowing heat to be transferred more quickly from the burning material to the surrounding environment. Sodium carbonate and potassium carbonate primarily exert their cooling effect by absorbing heat and increasing the thermal conductivity of the solution, making them suitable for extinguishing solid fires. The molten salts formed by potassium chloride and sodium chloride at high temperatures can cover the fuel surface, isolating oxygen and exhibiting good chemical inhibition. They are suitable for extinguishing both liquid and solid fires.

[0067] In some embodiments, the raw materials for preparing the water-based fire extinguishing agent 210 also include an antifreeze agent. Exemplarily, the antifreeze agent includes, but is not limited to, low concentrations of ethylene glycol or propylene glycol.

[0068] It is understandable that by adding antifreeze, the freezing point of water-based fire extinguishing agent 210 is lowered so that it can still maintain good fluidity under low temperature conditions. This ensures the antifreeze effect of the fire extinguishing microcapsules while minimizing the impact on cooling capacity and chemical inhibition, and improving adaptability to the use environment.

[0069] It should be noted that, considering that the higher the concentration of the inorganic salt aqueous solution, the lower its freezing point, the amount of antifreeze added is inversely proportional to the concentration of the inorganic salt aqueous solution, in order to reduce the impact on the fire extinguishing performance of the fire extinguishing microcapsules.

[0070] In some embodiments, the raw materials for preparing the water-based fire extinguishing agent 210 further include 0.1% to 5% by mass of a water-based surfactant.

[0071] Understandably, water-based surfactants not only significantly reduce the surface tension of water, making it easier for water-based fire extinguishing agent 210 to spread on the surface of burning materials, thereby increasing the coverage area of ​​the fire, but also improve the wettability of the burning material surface, allowing it to adhere better and preventing the formation of water droplets due to excessive surface tension, thus improving fire extinguishing efficiency. Simultaneously, water-based surfactants can also improve the chemical stability of water-based fire extinguishing agent 210, preventing inorganic salts and other components from crystallizing during storage, ensuring the uniformity and performance consistency of water-based fire extinguishing agent 210. Furthermore, a concentration of 0.1% to 5% by mass of water-based surfactant can reduce the possibility of excessive foaming caused by excessive surfactant concentration, ensuring spray performance.

[0072] In some embodiments, the aqueous surfactant includes at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0073] Understandably, sodium dodecyl sulfate is a strong base-weak acid salt with good surface activity and foaming properties. Sodium dodecylbenzene sulfonate is an anionic surfactant with good surface activity and wetting properties. Both can significantly reduce the surface tension of water, making water-based fire extinguishing agent 210 easier to spread on the surface of burning materials.

[0074] In some embodiments, the mass ratio of the capsule shell 100 to the capsule core 200 is K2, and K2 satisfies: 1 / 9 ≤ K2 ≤ 1. This balances the fire extinguishing performance and structural stability of the fire extinguishing microcapsule, achieving maximum scalability while improving its fire extinguishing performance.

[0075] In some embodiments, the diameter of the fire extinguishing microcapsule is D, and D satisfies: 100μm≤D≤1000μm, so as to form a uniform mist distribution as much as possible during the spraying process, and to cover the combustion area more extensively.

[0076] In some embodiments, the raw materials for preparing the fluorinated fire extinguishing agent 220 include perfluorohexanone. Of course, in other embodiments, the raw materials for preparing the fluorinated fire extinguishing agent 220 may also include heptafluoropropane, etc., and this embodiment does not impose specific limitations on this.

[0077] Understandably, perfluorohexanone, with the chemical formula C6F12O, is a colorless, transparent, and odorless liquid at room temperature with a low boiling point. This makes it readily vaporized when heated, absorbing a large amount of heat and rapidly lowering the ambient temperature, thus reducing the temperature of the burning material below its ignition point and effectively suppressing the fire. Simultaneously, perfluorohexanone can participate in the chemical reactions of combustion, reducing carbon dioxide production and forming a protective gas film on the surface of the burning material, improving both fire extinguishing and environmental benefits.

[0078] In some embodiments, the raw materials for preparing the shell 100 include photopolymerizable resins. Exemplarily, photopolymerizable resins include, but are not limited to, acrylate resins, epoxy acrylates, or polyurethane acrylates.

[0079] Understandably, photopolymerizable resins can be rapidly cured under ultraviolet or visible light irradiation, making the preparation process of the capsule 100 more efficient, enabling the encapsulation of fire extinguishing microcapsules in a short time, and giving the fire extinguishing microcapsules good mechanical strength.

[0080] This application also provides a method for preparing the above-mentioned fire extinguishing microcapsules.

[0081] like Figure 2 As shown, the preparation method of the fire extinguishing microcapsule includes:

[0082] 410. Obtain the raw materials for preparing the core 200 and the shell 100, wherein the core 200 includes immiscible water-based fire extinguishing agent 210 and fluorine-based fire extinguishing agent 220.

[0083] 420. The raw materials for preparing the capsule core 200 and the raw materials for preparing the capsule shell 100 are respectively injected into the microfluidic device 300, and microdroplets are formed based on coaxial flow or flow focusing technology.

[0084] It should be noted that coaxial flow and flow focusing are two typical mechanisms in microfluidics for generating monodisperse microdroplets based on capillary devices. Both rely on the hydrodynamic interaction of two immiscible phases (dispersed phase and continuous phase) within a multidimensional microstructure, but they differ significantly in their specific implementation and droplet generation characteristics. In coaxial flow, as the dispersed phase flows out of the inner tube of the coaxial capillary device, continuous shear force acts on the interface between the two phases, eventually overcoming interfacial tension and "cutting off" the dispersed phase flow to form uniformly sized microdroplets. This technique is simple in structure and stable in operation, easily achieving uniform droplet preparation at low generation frequencies, but it is sensitive to flow rate ratios, and the flexibility in microdroplet size control is limited. In flow focusing, both fluid phases are guided to a narrow focusing orifice or contraction region. The high-speed continuous phase generates strong tensile and shear forces as it passes through the focusing orifice. These forces act on the dispersed phase flow, causing it to be rapidly thinned and stretched at the orifice inlet or inside, eventually breaking up to form microdroplets. This method generates droplets with high frequency and good size uniformity, and the droplet size can be precisely controlled by adjusting the size of the constraint hole and the two-phase flow rate. However, its structure is complex to manufacture and the operating window is relatively narrow.

[0085] 430. The microdroplets are subjected to UV curing treatment so that the capsule shell 100 covers the capsule core 200 to obtain fire extinguishing microcapsules.

[0086] For example, the preparation method of the entire fire extinguishing microcapsule is as follows:

[0087] An inorganic salt aqueous solution obtained by mixing sodium chloride and water was used as a raw material for preparing water-based fire extinguishing agent 210, perfluorohexanone was used as a raw material for preparing fluorine-based fire extinguishing agent 220, and photopolymer resin solution was used as a raw material for preparing shell 100.

[0088] The raw materials were injected into the corresponding needles of the microfluidic device 300 using injection pumps, and the flow rate of each raw material was controlled to obtain microdroplets under shearing action.

[0089] The microdroplets are UV-cured so that the capsule 100 covers the water-based fire extinguishing agent 210 and the fluorine-based fire extinguishing agent 220, thus obtaining fire extinguishing microcapsules.

[0090] It should be noted that precise encapsulation between the core 200 and the shell 100 is achieved through coaxial flow or flow focusing technology, and a structurally stable fire extinguishing microcapsule is formed by combining it with a curing process.

[0091] It is understandable that by preparing immiscible water-based extinguishing agent 210 and fluorine-based extinguishing agent 220 inside the capsule 100, the fluorine-based extinguishing agent 220, due to its low boiling point and high vapor pressure, preferentially vaporizes and breaks through the capsule 100 to release, thereby quickly blocking the chain reaction of combustion. The water-based extinguishing agent 210 is then released a second time upon heating and expansion, continuously cooling down through vaporization and heat absorption. By utilizing the difference in physical properties between the two, a self-driven, staged release is achieved, improving the overall fire extinguishing efficiency of the fire extinguishing microcapsule.

[0092] According to the method for preparing fire extinguishing microcapsules provided in the embodiments of this application, the synergistic effect of water-based fire extinguishing agent 210 and fluorine-based fire extinguishing agent 220 is utilized to achieve a dual fire extinguishing mechanism of "physical + chemical" and improve the fire extinguishing effect as much as possible.

[0093] In some embodiments, in step 420, in the microfluidic device 300, the flow rate ratio of the raw material for preparing the core 200 to the raw material for preparing the shell 100 is K3, and K3 satisfies: 0.5≤K3≤2.

[0094] It is understandable that by controlling the flow rate of the raw materials used to prepare the core 200 and the shell 100, the thickness of the shell 100 can be kept moderate and the coating can be made uniform. This reduces the possibility that the shell 100 may not be fully formed due to the slow flow rate of the raw materials used to prepare the shell 100, thus exposing the core 200. It also reduces the possibility that the shell 100 may be too thick due to the fast flow rate of the raw materials used to prepare the shell 100, which would affect the mechanical properties and release performance of the fire extinguishing microcapsules.

[0095] For example, combined Figure 1As shown, the microfluidic device 300 includes an outer phase needle and two inner phase needles arranged side by side. The inner phase needles are inserted into the outer phase needles. Inorganic salt aqueous solution and perfluorohexanone are injected into the two inner phase needles respectively. Photopolymerization resin solution is passed into the outer phase needle. Polyvinyl alcohol aqueous solution is used as the driving phase to prepare microdroplets that simultaneously encapsulate inorganic salt aqueous solution and perfluorohexanone by photopolymerization resin solution.

[0096] In some embodiments, in step 430, the microdroplets are irradiated with UV light, the UV light wavelength being 365 nm and the power range being 3~10 mW / cm². 2 The exposure time ranges from 5 to 20 seconds.

[0097] Understandably, 365nm ultraviolet light has strong penetrating power, ensuring sufficient curing inside the capsule 100. Simultaneously, utilizing 3~10mW / cm²... 2 The power range ensures sufficient energy to excite the UV photoinitiator in the raw material used to prepare the capsule 100, while reducing the possibility of degradation or performance decline in the raw material used to prepare the capsule 100 due to overexposure. In addition, the exposure time of 5 to 20 seconds also ensures that the UV curing reaction proceeds fully, while reducing the possibility of aging or performance decline in the raw material used to prepare the capsule 100 due to excessive exposure time.

[0098] Furthermore, the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Additionally, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0099] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0100] In the description of this application, "first feature" and "second feature" may include one or more of the features.

[0101] In the description of this application, "multiple" means two or more.

[0102] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them.

[0103] In the description of this application, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0104] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A fire extinguishing microcapsule, characterized in that, include: The core of the fire extinguishing agent comprises immiscible water-based fire extinguishing agent and fluorine-based fire extinguishing agent; A capsule shell, which covers the core; wherein, The mass ratio of the water-based fire extinguishing agent to the fluorine-based fire extinguishing agent is K1, and K1 satisfies: 0.5 ≤ K1 ≤ 2; where, The raw materials for preparing the water-based fire extinguishing agent include one of seawater and an aqueous solution of inorganic salts, wherein the aqueous solution of inorganic salts includes at least one of potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, potassium chloride, or sodium chloride aqueous solution; the raw materials for preparing the fluorine-based fire extinguishing agent include perfluorohexanone.

2. The fire extinguishing microcapsule according to claim 1, characterized in that, The raw materials for preparing the water-based fire extinguishing agent also include antifreeze.

3. The fire extinguishing microcapsule according to claim 1 or 2, characterized in that, The raw materials for preparing the water-based fire extinguishing agent also include 0.1% to 5% by mass of water-based surfactants.

4. The fire extinguishing microcapsule according to claim 3, characterized in that, The aqueous surfactant includes at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

5. The fire extinguishing microcapsule according to claim 1 or 2, characterized in that, The mass ratio of the shell to the core is K2, and K2 satisfies: 1 / 9 ≤ K2 ≤ 1.

6. The fire extinguishing microcapsule according to claim 1 or 2, characterized in that, The diameter of the fire extinguishing microcapsule is D, and D satisfies: 100μm≤D≤1000μm.

7. The fire extinguishing microcapsule according to claim 1 or 2, characterized in that, The raw materials for preparing the capsule include photopolymerizable resin.

8. A method for preparing fire extinguishing microcapsules according to any one of claims 1 to 7, characterized in that, include: Obtain raw materials for preparing the core and shell of the fire extinguishing agent, wherein the core comprises immiscible water-based fire extinguishing agent and fluorine-based fire extinguishing agent; The raw materials for preparing the capsule core and the raw materials for preparing the capsule shell are injected into the needle of the microfluidic device, and microdroplets are formed based on coaxial flow or flow focusing technology. The microdroplets are subjected to UV curing treatment so that the capsule shell covers the capsule core, thereby obtaining the fire extinguishing microcapsule.

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