Process for the preparation of fire extinguishing microcapsules

Abstract

The application discloses a preparation method of fire-extinguishing microcapsules, and belongs to the technical field of fire extinguishing. The fire-extinguishing microcapsules comprise a capsule core and a capsule shell, and the raw material for preparing the capsule core comprises a water-based fire extinguishing agent; the capsule shell comprises an interface polymerization layer and a UV curing layer arranged in sequence from inside to outside, and the water-based fire extinguishing agent is coated in the interface polymerization layer. On one hand, the interface polymerization layer is a film formed through an interface polymerization reaction, i.e. formed by utilizing the hydrophilicity of the water-based fire extinguishing agent and the lipophilicity of the capsule shell, so that the sealing property and the flexibility are improved; on the other hand, the UV curing layer is formed by curing the raw material for preparing the capsule shell through an inter-reaction under ultraviolet irradiation, so that the impact resistance and the deformation resistance of the capsule shell are improved, and the mechanical strength and the high-temperature resistance of the capsule shell are improved. In addition, the outer UV curing layer and the inner interface polymerization layer are formed in stages from early to late, so that the mechanical strength of the capsule shell is improved, and the possibility of water-based fire extinguishing agent seepage and loss is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fire extinguishing, and particularly relates to a preparation method of fire extinguishing microcapsules. BACKGROUND

[0002] The fire extinguishing microcapsule is an intelligent fire extinguishing material in which a fire extinguishing agent is wrapped in a micro polymer capsule, and the fire extinguishing agent is released by external stimulation (such as heat, pressure or chemical triggering) to achieve precise and efficient fire extinguishing. However, the capsule shell of the fire extinguishing microcapsule prepared by the microflow control method is usually prepared by a UV curing process, and it is difficult to achieve complete uniform crosslinking curing at the micro-nano scale. Moreover, due to the limitations of the penetration and distribution of ultraviolet light in the micro capsule, local curing deficiency or structural defects may occur in the capsule shell, resulting in insufficient mechanical strength and poor thermal stability of the fire extinguishing microcapsule. The fire extinguishing microcapsule is prone to unintended rupture in storage, transportation or under pressure, and it is difficult to meet the high-temperature triggering release requirement, which affects the fire extinguishing performance. SUMMARY

[0003] The application provides a preparation method of fire extinguishing microcapsules. By arranging a UV curing layer and an interfacial polymerization layer, the mechanical strength and compactness of the capsule shell are effectively improved, so that the high-temperature triggering release requirement of the fire extinguishing microcapsule can be effectively met.

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

[0005] A capsule core, the raw material for preparing the capsule core comprising a water-based fire extinguishing agent;

[0006] A capsule shell, the capsule shell comprising an interfacial polymerization layer and a UV curing layer arranged in sequence from inside to outside, and the water-based fire extinguishing agent being coated in the interfacial polymerization layer.

[0007] According to the fire extinguishing microcapsule of the application, the water-based fire extinguishing agent is coated by the double layers of the interfacial polymerization layer and the UV curing layer, so that the mechanical strength and compactness of the fire extinguishing microcapsule are improved. On the one hand, the interfacial polymerization layer is a film formed by interfacial polymerization reaction, which is formed by using the hydrophilicity of the water-based fire extinguishing agent and the lipophilicity of the capsule shell to improve the sealing property and flexibility. On the other hand, the UV curing layer is formed by crosslinking and curing of the raw material for preparing the capsule shell by ultraviolet irradiation, which can enhance the impact resistance and deformation resistance of the capsule shell, and improve the mechanical strength and high temperature resistance of the capsule shell. In addition, the outer UV curing layer and the inner interfacial polymerization layer are formed in stages from first to last, so that the mechanical strength of the capsule shell is improved while the possibility of water-based fire extinguishing agent seepage loss is reduced.

[0008] According to one embodiment of the present application, the raw material for preparing the capsule core further comprises 4-6% mass concentration of ethylenediamine and 0.3-0.8% mass concentration of emulsifier, based on the total mass of the raw material for preparing the capsule core; the raw material for preparing the capsule shell comprises 6-10% mass concentration of toluene diisocyanate, 0.8-1.5% mass concentration of interfacial polymerization catalyst and 3-6% mass concentration of curing active diluent, the interfacial polymerization layer comprises a polyurea layer.

[0009] According to one embodiment of the present application, the interfacial polymerization catalyst is dibutyltin dilaurate; and / or

[0010] The curing active diluent is 1,6-hexanediol diacrylate.

[0011] According to one embodiment of the present application, the raw material for preparing the capsule shell further comprises 82-86% mass concentration of polyurethane acrylate and 0.6-1.5% mass concentration of UV photoinitiator, based on the total mass of the raw material for preparing the capsule shell.

[0012] According to one embodiment of the present application, the UV photoinitiator is 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide.

[0013] According to one embodiment of the present application, the pH value of the raw material for preparing the capsule core ranges from 8 to 9.

[0014] According to one embodiment of the present application, the water-based fire extinguishing agent comprises 3-6% mass concentration of F500, based on the total mass of the raw material for preparing the capsule core.

[0015] In a second aspect, the present application provides a preparation method of the fire extinguishing microcapsule as described above, comprising:

[0016] obtaining raw materials for preparing the capsule core and the capsule shell;

[0017] injecting the raw material for preparing the capsule core and the raw material for preparing the capsule shell into a microfluidic device respectively, and forming microdroplets based on coaxial flow technology or flow focusing technology;

[0018] subjecting the microdroplets to UV curing treatment and interfacial polymerization reaction to obtain the fire extinguishing microcapsule.

[0019] According to the preparation method of the fire extinguishing microcapsule of the present application, the microdroplets are subjected to UV curing and interfacial polymerization reaction to form a UV curing layer and an interfacial polymerization layer, so that the mechanical strength and compactness of the capsule shell are effectively improved, thereby effectively ensuring the requirement of high-temperature trigger release of the fire extinguishing microcapsule.

[0020] According to one embodiment of the present application, the UV curing treatment and the interfacial polymerization reaction on the microdroplets are performed to obtain the fire extinguishing microcapsules, which comprises:

[0021] UV light is irradiated on the microdroplets to form a UV cured layer outside the capsule core;

[0022] The microdroplets with the UV cured layer are transferred to an interfacial polymerization reaction tank to perform an interfacial polymerization reaction between the water-based fire extinguishing agent and the UV cured layer to form an interfacial polymerization layer, thereby obtaining the fire extinguishing microcapsules; wherein,

[0023] The UV light wavelength is 365 nm, the power range is 3-10 mW / cm 2 , and the exposure time range is 5-20 seconds; and / or

[0024] The interfacial polymerization reaction temperature range is 25-60℃, and the interfacial polymerization reaction time is 2-6 hours.

[0025] According to one embodiment of the present application, the raw materials for preparing the capsule core and the raw materials for preparing the capsule shell are injected into the microfluidic device respectively, and the microdroplets are formed based on coaxial flow technology or flow focusing technology; which comprises:

[0026] In the microfluidic device, the flow rate ratio of the raw materials for preparing the capsule core and the raw materials for preparing the capsule shell is K1, and K1 satisfies: 0.5≤K1≤2.

[0027] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter in the description of embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0028] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the description of embodiments, taken in conjunction with the following drawings in which:

[0029] Figure 1 is one of the structural schematic diagrams of the fire extinguishing microcapsules provided by the embodiments of the present application;

[0030] Figure 2 is a thermogravimetric diagram of the fire extinguishing microcapsules provided by the embodiments of the present application;

[0031] Figure 3 is a bright field image of the fire extinguishing microcapsules under a microscope provided by the embodiments of the present application;

[0032] Figure 4 is an electron microscope diagram of the fire extinguishing microcapsules in the related art provided by the embodiments of the present application;

[0033] Figure 5 is a flowchart of the preparation method of the fire extinguishing microcapsules provided by the embodiments of the present application.

[0034] Figure label:

[0035] 100. Shell; 110. UV-cured layer; 120. Interface polymerization layer;

[0036] 200. Core. Detailed Implementation

[0037] 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.

[0038] The following is for reference. Figures 1-4 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.

[0039] The raw materials for preparing the core 200 include a water-based fire extinguishing agent; the shell 100 includes an interface polymerization layer 120 and a UV curing layer 110 arranged sequentially from the inside to the outside, with the water-based fire extinguishing agent encapsulated within the interface polymerization layer 120.

[0040] It should be noted that water-based fire extinguishing agents have good fire extinguishing and environmental performance. They mainly achieve the purpose of extinguishing fires by reducing the combustion temperature through cooling.

[0041] Understandably, by setting the interfacial polymerization layer 120 and the UV curing layer 110, the water-based fire extinguishing agent is double-coated, improving the mechanical strength and density of the fire extinguishing microcapsule. On one hand, the interfacial polymerization layer 120 is a thin film formed through an interfacial polymerization reaction, utilizing the hydrophilicity of the water-based fire extinguishing agent and the oleophilicity of the capsule shell 100, thus improving sealing and flexibility. On the other hand, the UV curing layer 110 is formed by curing the raw materials used to prepare the capsule shell 100 through cross-linking under ultraviolet light, which enhances the impact resistance and deformation resistance of the capsule shell 100, and improves its mechanical strength and high-temperature resistance. In addition, the outer UV curing layer 110 and the inner interfacial polymerization layer 120 are formed in stages from one to the other, thereby improving the mechanical strength of the capsule shell 100 while reducing the possibility of water-based fire extinguishing agent penetration and loss.

[0042] For example, combined Figures 2 to 4 As shown, the core 200 of samples 1 and 2 uses the same water-based extinguishing agent, and the mass of the core 200 of each sample accounts for 75% of the total mass. Sample 1 (combined with...) Figure 4The capsule shell of sample 1 (shown) only includes the UV curing layer 110, while the capsule shell 100 of sample 2 includes the interface polymerization layer 120 and the UV curing layer 110. The vertical axis represents the remaining weight percentage of the capsule core 200, and the horizontal axis represents the temperature. It can be seen that the release temperature of the capsule core 200 of sample 1 is about 110℃, and the release temperature of the capsule core 200 of sample 2 is about 130℃, which effectively improves the stability of the fire extinguishing microcapsule.

[0043] The preparation method of sample 1 is as follows:

[0044] A certain amount of F-500 and emulsifier are added to an aqueous solution and mixed evenly to obtain the raw material for preparing the core 200. Based on the total mass of the raw material for the core 200, the raw material includes 3% F-500 by mass concentration and 0.5% emulsifier by mass concentration (i.e., by mass parts, the raw material includes: 3 parts F-500, 0.5 parts emulsifier and 96.5 parts water).

[0045] A certain amount of polyurethane acrylate, UV photoinitiator and curing reactive diluent are mixed evenly to obtain the raw material for preparing the shell 100. Based on the total mass of the raw material of the shell 100, the raw material includes 94% by mass of polyurethane acrylate, 1% by mass of UV photoinitiator and 5% by mass of curing reactive diluent.

[0046] The raw materials for preparing the core 200 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 0.3 mL / h and 0.1 mL / h, respectively. A 4% polyvinyl alcohol solution was used as the driving phase and its flow rate was 5 mL / h to obtain microdroplets with a diameter range of 200~300 μm.

[0047] By irradiating the microdroplets with UV light, a UV-cured layer 110 is formed on the outside of the core 200, thus obtaining a fire extinguishing microcapsule.

[0048] The fire extinguishing microcapsules were washed sequentially with hexane, ethanol and deionized water, and then vacuum dried at 35°C.

[0049] The preparation method of sample 2 is as follows:

[0050] A certain amount of F-500, ethylenediamine, and emulsifier are added to an aqueous solution and mixed evenly to obtain the raw material for preparing the core 200. Based on the total mass of the raw material for the core 200, the raw material includes 3% F-500 by mass, 5% ethylenediamine by mass, and 0.5% emulsifier by mass (i.e., by mass parts, the raw material includes: 3 parts F-500, 5 parts ethylenediamine, 0.5 parts emulsifier, and 91.5 parts water).

[0051] Phosphate buffer was slowly added to the raw materials for preparing capsule core 200 by titration until the pH value was adjusted to 8.5, and the mixture was continuously stirred during the adjustment process to ensure that the pH value was uniform and stable.

[0052] A certain amount of polyurethane acrylate, toluene diisocyanate, UV photoinitiator, interfacial polymerization catalyst and curing active diluent are mixed evenly to obtain the raw material for preparing the capsule shell 100. Based on the total mass of the raw material of the capsule shell 100, the raw material includes 85% by mass of polyurethane acrylate, 8% by mass of toluene diisocyanate, 1% by mass of UV photoinitiator, 1% by mass of interfacial polymerization catalyst and 5% by mass of curing active diluent.

[0053] The raw materials for preparing the core 200 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 0.3 mL / h and 0.1 mL / h, respectively. A 4% polyvinyl alcohol solution was used as the driving phase and its flow rate was 5 mL / h to obtain microdroplets with a diameter range of 200~300 μm.

[0054] The microdroplets are irradiated with UV light to form a UV-cured layer 110 on the outside of the core 200;

[0055] The microdroplets forming the UV-cured layer 110 were transferred to an interfacial polymerization reaction tank at 40°C and stirred for 4 hours to allow an interfacial polymerization reaction to occur between the water-based fire extinguishing agent and the UV-cured layer 110, forming an interfacial polymer layer 120, thus obtaining fire extinguishing microcapsules;

[0056] The fire extinguishing microcapsules were washed sequentially with hexane, ethanol and deionized water, and then vacuum dried at 35°C.

[0057] Continuing from the previous example, combined with Figure 3 and Figure 4 As shown, the data obtained for Sample 1 and Sample 2 in an 80℃ forced-air drying oven are shown in Table 1 below:

[0058] Table 1

[0059]

[0060] Understandably, in an 80°C forced-air drying oven environment, the capsule containing only the UV curing layer 110 lost almost all of the water-based extinguishing agent after 30 minutes, while the capsule containing both the UV curing layer 110 and the interface polymerization layer 120 released only 52% of the agent after 30 minutes and was coated with a small amount of water-based extinguishing agent after 2 hours, thus improving the sustained-release performance of the extinguishing microcapsule and improving the storage stability of the capsule core 200.

[0061] Continuing from the previous example, combined with Figure 3 and Figure 4As shown, the data for samples 1 and 2 obtained under a 25°C, well-ventilated, and dry environment are shown in Table 2 below:

[0062] Table 2

[0063]

[0064] Understandably, in a 25°C and well-ventilated, dry environment, the capsule containing only the UV curing layer 110 had almost completely lost the water-based extinguishing agent by day 7, while the capsule containing both the UV curing layer 110 and the interface polymerization layer 120 only released 8% by day 7, and still contained a large amount of water-based extinguishing agent after 25 days, thus improving the sustained-release performance of the extinguishing microcapsule and thus enhancing the storage stability of the capsule core 200.

[0065] According to the fire extinguishing microcapsule provided in the embodiments of this application, by setting a UV curing layer 110 and an interface polymerization layer 120, the mechanical strength and density of the capsule shell 100 are effectively improved, thereby effectively ensuring the requirement of high-temperature triggering release of the fire extinguishing microcapsule.

[0066] In some embodiments, based on the total mass of the raw materials in the core 200, the water-based extinguishing agent includes 3-6% by mass of F500. Of course, in other embodiments, 1-3% by mass of Faande 2000 water-based extinguishing agent, or premixed water containing 6% by mass of aqueous film-forming foam extinguishing agent and 1% by mass of Class A foam extinguishing agent, or water containing dissolved chemical decontamination agents may also be added. This embodiment does not impose specific limitations on these.

[0067] Understandably, F500 can rapidly lower the boiling point of water and form a protective gas film on the surface of burning materials, improving both fire extinguishing and environmental benefits. However, if the concentration of F500 is too low, the wetting rate of the water-based extinguishing agent will be poor, making it difficult to cover the burning materials and thus affecting the suffocation effect; if the concentration of F500 is too high, the water content will be reduced, thus affecting the cooling effect.

[0068] In some embodiments, based on the total mass of the raw materials for the core 200, the raw materials for preparing the core 200 further include 4-6% by mass of ethylenediamine and 0.3-0.8% by mass of emulsifier; based on the total mass of the raw materials for the shell 100, the raw materials for preparing the shell 100 include 6-10% by mass of toluene diisocyanate, 0.8-1.5% by mass of interfacial polymerization catalyst, and 3-6% by mass of curing reactive diluent, and the interfacial polymerization layer 120 includes a polyurea layer. Exemplarily, the emulsifier is a nonionic emulsifier, including but not limited to Pluronic F68.

[0069] It is understood that the polyurea layer is formed by interfacial polymerization of toluene diisocyanate and ethylenediamine. Simultaneously, ethylenediamine also acts as a crosslinking agent, improving the stability of the core 200 and reducing the possibility of F500 decomposition. The emulsifier ensures uniform dispersion of F500, preventing agglomeration that could affect the coating effect. The interfacial polymerization catalyst accelerates the formation of the polyurea layer, improving the efficiency and quality of the interfacial polymerization reaction. The curing reactive diluent adjusts the curing speed and mechanical properties of the shell 100, facilitating the molding of the polyurea layer. Of course, in other embodiments, toluene diisocyanate can be replaced with hexamethylene diisocyanate; this embodiment does not impose specific limitations on this.

[0070] In some embodiments, the interfacial polymerization catalyst is dibutyltin dilaurate.

[0071] It is understandable that dibutyltin dilaurate is a commonly used organotin catalyst. When its mass concentration is within the range of 0.8% to 1.5%, it can not only ensure the efficient progress of the interfacial polymerization reaction, but also guarantee the uniformity and integrity of the polyurea layer. It can also reduce the possibility of the capsule 100 being catalyzed due to excessive cross-linking of the polyurea layer caused by excessive amount.

[0072] In some embodiments, the curing reactive diluent is 1,6-hexanediol diacrylate.

[0073] Understandably, 1,6-hexanediol diacrylate is a bifunctional acrylate compound with high reactivity. It not only participates in the UV curing reaction, enhancing the mechanical properties of the UV-cured layer 110, but also effectively reduces viscosity, facilitating the molding of the polyurea layer. Furthermore, the relatively long chain segments of 1,6-hexanediol impart a degree of flexibility to the UV-cured layer 110, preventing cracking caused by excessive brittleness.

[0074] In some embodiments, the pH value of the raw material used to prepare the core 200 is in the range of 8 to 9.

[0075] Understandably, by keeping the pH range of the raw materials used to prepare the capsule core 200 between 8 and 9, on the one hand, toluene diisocyanate is more easily hydrolyzed to generate amine groups under alkaline conditions, which can accelerate the polycondensation reaction with ethylenediamine to form a polyurea layer; on the other hand, F500 is more stable under weakly alkaline conditions than in acidic environments, which can inhibit the decomposition of F500 and make the HLB value (hydrophilic-lipophilic balance value) of the emulsifier activity more stable, ensuring that the capsule core 200 is uniformly dispersed.

[0076] In some embodiments, based on the total mass of the raw materials for the capsule 100, the raw materials for preparing the capsule 100 further include 82-86% by mass of polyurethane acrylate and 0.6-1.5% by mass of UV photoinitiator. Of course, in other embodiments, the raw materials for preparing the capsule 100 may also include other polymeric materials, and this embodiment does not limit this. Exemplarily, the UV photoinitiator includes, but is not limited to, bis(acylphosphine) oxide.

[0077] Understandably, polyurethane acrylate is a polymer material that combines the properties of both polyurethane and acrylate. Polyurethane provides excellent flexibility and mechanical strength, while acrylate provides good hardness and abrasion resistance, thus achieving stability even at high temperatures and good adhesion to the polyurea layer, improving the reliability of the shell 100. The UV photoinitiator can rapidly initiate the cross-linking of the acrylate under ultraviolet irradiation, improving the overall mechanical strength of the shell 100.

[0078] In some embodiments, the UV photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0079] Understandably, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) is a highly efficient UV photoinitiator that can rapidly decompose under ultraviolet light, generating free radicals that initiate the polymerization reaction of acrylate monomers. This efficient initiation capability allows the UV curing layer 110 to cure rapidly in a short time, forming a hard outer shell.

[0080] In some embodiments, the mass ratio of the core 200 to the fire extinguishing microcapsule is K2, and K2 satisfies: 60%≤K2≤75%.

[0081] Understandably, the core 200 accounts for 60% to 75% of the total mass of the fire extinguishing microcapsule in order to balance the fire extinguishing performance and structural stability of the fire extinguishing microcapsule, thereby achieving the largest possible scale of production while improving the fire extinguishing performance of the fire extinguishing microcapsule.

[0082] In some embodiments, the diameter of the fire extinguishing microcapsules ranges from 50 μm to 500 μm, so as to form a uniform mist distribution during spraying and to cover the combustion area more extensively.

[0083] This application also provides a method for preparing the above-mentioned fire extinguishing microcapsules.

[0084] like Figure 5 As shown, the preparation method of the fire extinguishing microcapsule includes:

[0085] 410. Obtain the raw materials for preparing the core 200 and the shell 100.

[0086] 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, and microdroplets are formed based on coaxial flow technology or flow focusing technology.

[0087] 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.

[0088] 430. Microdroplets were subjected to UV curing and interfacial polymerization to obtain fire extinguishing microcapsules.

[0089] For example, the preparation method of the entire fire extinguishing microcapsule is as follows:

[0090] Polyurethane acrylate, toluene diisocyanate, UV photoinitiator, interfacial polymerization catalyst and curing active diluent are mixed evenly to obtain the raw material for preparing the capsule shell 100.

[0091] F-500, ethylenediamine and emulsifier were added to an aqueous solution and mixed evenly to obtain the raw material for preparing the core 200;

[0092] Microdroplets were obtained by injecting the raw materials into the corresponding needles of the microfluidic device using an injection pump and controlling the flow rate of each material under shearing action.

[0093] The microdroplets are subjected to UV curing and interfacial polymerization reactions, so that the outer surface of the microdroplets is solid, forming a UV-cured layer 110 and an interfacial polymerization layer 120 of the capsule 100, thus obtaining a fire extinguishing microcapsule.

[0094] Understandably, by setting the interfacial polymerization layer 120 and the UV curing layer 110, the water-based fire extinguishing agent is double-coated, improving the mechanical strength and density of the fire extinguishing microcapsule. On the one hand, the interfacial polymerization layer 120 is a thin film formed through an interfacial polymerization reaction, utilizing the hydrophilicity of the water-based fire extinguishing agent and the oleophilicity of the capsule shell 100, thus improving sealing and flexibility. On the other hand, the UV curing layer 110 is formed by curing the raw materials used to prepare the capsule shell 100 through cross-linking under ultraviolet light, which enhances the impact resistance and deformation resistance of the capsule shell 100, and improves its mechanical strength and high-temperature resistance.

[0095] According to the method for preparing fire extinguishing microcapsules provided in the embodiments of this application, by performing UV curing and interfacial polymerization reaction on microdroplets to form a UV curing layer 110 and an interfacial polymerization layer 120, the mechanical strength and density of the capsule shell 100 are effectively improved, thereby effectively ensuring the requirement of high-temperature triggering release of fire extinguishing microcapsules.

[0096] In some embodiments, step 430 specifically includes:

[0097] 431. The microdroplets are irradiated with UV light to form a UV-cured layer 110 on the outside of the core 200;

[0098] 432. The microdroplets forming the UV-cured layer 110 are transferred to the interfacial polymerization reaction tank to form an interfacial polymerization layer 120 between the water-based fire extinguishing agent and the UV-cured layer 110, thereby obtaining fire extinguishing microcapsules.

[0099] It is understandable that the outer UV curing layer 110 and the inner interface polymerization layer 120 are formed in stages from one to the next, which can effectively reduce the occurrence of fire extinguishing microcapsules being easily damaged and make the size and shape of the microdroplets more uniform, which is conducive to improving the microcapsule yield and reducing the possibility of water-based fire extinguishing agent penetration and loss while improving the mechanical strength of the capsule shell 100.

[0100] In some embodiments, in step 420, in the microfluidic device, the flow rate ratio of the raw material for preparing the core 200 to the raw material for preparing the shell 100 is K1, and K1 satisfies: 0.5≤K1≤2.

[0101] 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.

[0102] In some embodiments, in step 431, the UV light wavelength is 365 nm and the power range is 3~10 mW / cm². 2 The exposure time ranges from 5 to 20 seconds.

[0103] Understandably, 365nm ultraviolet light has strong penetrating power, ensuring sufficient curing of the UV curing layer 110. Simultaneously, utilizing 3~10mW / cm²... 2 The power range ensures sufficient energy to excite the UV photoinitiator while reducing the possibility of degradation or performance decline of the raw materials used to prepare the capsule 100 due to overexposure. Furthermore, the exposure time of 5–20 seconds ensures the UV curing reaction proceeds fully while minimizing the possibility of aging or performance decline of the raw materials used to prepare the capsule 100 due to excessive exposure time.

[0104] In some embodiments, in step 432, the interfacial polymerization reaction temperature ranges from 25 to 60°C, and the interfacial reaction time is from 2 to 6 hours. For example, the reaction temperature is 40°C, and the reaction time is 4 hours.

[0105] Understandably, a temperature range of 25–60°C helps reduce localized overheating or incomplete reactions, thereby improving the quality and uniformity of the polyurea layer. A reaction time of 2–6 hours ensures the full formation of the polyurea layer.

[0106] In some embodiments, in step 432, a constant temperature magnetic stirrer can be used to stir the interfacial polymerization reaction tank to ensure that the raw materials for preparing the shell 100 and the core 200 are fully mixed, thereby improving the uniformity and efficiency of the interfacial polymerization reaction.

[0107] In some embodiments, step 430 is followed by:

[0108] 440. Wash and vacuum dry the fire extinguishing microcapsules.

[0109] Understandably, washing and vacuum drying the fire extinguishing microcapsules formed through UV curing and interfacial polymerization reactions can ensure their performance and quality. Washing removes residual reaction byproducts, unreacted raw materials, and potential impurities from the surface of the microcapsules, thus minimizing their impact on mechanical strength, high-temperature resistance, and fire extinguishing performance. Vacuum drying removes residual moisture or other solvents from the inside and surface of the microcapsules, reducing the possibility of rupture due to internal pressure caused by moisture evaporation and improving the stability of the microcapsules during storage and transportation.

[0110] For example, the fire extinguishing microcapsules are washed sequentially with hexane, ethanol and deionized water, and then vacuum dried at a temperature range of 35~50°C.

[0111] For example, the preparation method of the entire fire extinguishing microcapsule is as follows:

[0112] A certain amount of F-500, ethylenediamine, and emulsifier are added to an aqueous solution and mixed evenly to obtain the raw material for preparing the core 200. Based on the total mass of the raw material for the core 200, the raw material includes 3% F-500 by mass, 5% ethylenediamine by mass, and 0.5% emulsifier by mass (i.e., by mass parts, the raw material includes: 3 parts F-500, 5 parts ethylenediamine, 0.5 parts emulsifier, and 91.5 parts water).

[0113] Phosphate buffer was slowly added to the raw materials for preparing capsule core 200 by titration until the pH value was adjusted to 8.5, and the mixture was continuously stirred during the adjustment process to ensure that the pH value was uniform and stable.

[0114] A certain amount of polyurethane acrylate, toluene diisocyanate, UV photoinitiator, interfacial polymerization catalyst and curing active diluent are mixed evenly to obtain the raw material for preparing the capsule shell 100. Based on the total mass of the raw material of the capsule shell 100, the raw material includes 85% by mass of polyurethane acrylate, 8% by mass of toluene diisocyanate, 1% by mass of UV photoinitiator, 1% by mass of interfacial polymerization catalyst and 5% by mass of curing active diluent.

[0115] The raw materials for preparing the core 200 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 0.1 mL / h and 0.5 mL / h, respectively. A 4% polyvinyl alcohol solution was used as the driving phase and its flow rate was 5 mL / h to obtain microdroplets with a diameter of 80 μm.

[0116] The microdroplets are irradiated with UV light to form a UV-cured layer 110 on the outside of the core 200;

[0117] The microdroplets forming the UV-cured layer 110 were transferred to an interfacial polymerization reaction tank at 40°C and stirred for 4 hours to form an interfacial polymerization layer 120 between the water-based fire extinguishing agent and the UV-cured layer 110, thus obtaining fire extinguishing microcapsules.

[0118] The fire extinguishing microcapsules were washed sequentially with hexane, ethanol and deionized water, and then vacuum dried at 35°C.

[0119] 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 method for preparing fire extinguishing microcapsules, characterized in that, The fire extinguishing microcapsule comprises: The core of the fire extinguishing agent is prepared from water-based fire extinguishing agents. The shell comprises an interfacial polymerization layer and a UV-curing layer arranged sequentially from the inside to the outside, wherein the water-based fire extinguishing agent is encapsulated within the interfacial polymerization layer; wherein the preparation method includes: Raw materials for preparing capsule cores and shells are obtained and microdroplets are formed; The microdroplets are irradiated with UV light to form a UV-cured layer on the outside of the core. Microdroplets forming a UV-cured layer are transferred to an interfacial polymerization reaction tank to form an interfacial polymerization layer between the water-based fire extinguishing agent and the UV-cured layer, thus obtaining fire extinguishing microcapsules.

2. The method for preparing fire extinguishing microcapsules according to claim 1, characterized in that, Based on the total mass of the raw materials for the core, the raw materials for preparing the core further include: 4-6% by mass of ethylenediamine and 0.3-0.8% by mass of emulsifier; based on the total mass of the raw materials for the shell, the raw materials for preparing the shell include: 6-10% by mass of toluene diisocyanate, 0.8-1.5% by mass of interfacial polymerization catalyst and 3-6% by mass of curing active diluent, wherein the interfacial polymerization layer includes a polyurea layer.

3. The method for preparing fire extinguishing microcapsules according to claim 2, characterized in that, The interfacial polymerization catalyst is dibutyltin dilaurate; and / or The curing reactive diluent is 1,6-hexanediol diacrylate.

4. The method for preparing fire extinguishing microcapsules according to claim 2, characterized in that, Based on the total mass of the raw materials for the capsule shell, the raw materials for preparing the capsule shell also include 82-86% by mass of polyurethane acrylate and 0.6-1.5% by mass of UV photoinitiator.

5. The method for preparing fire extinguishing microcapsules according to claim 4, characterized in that, The UV photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

6. The method for preparing fire extinguishing microcapsules according to claim 2, characterized in that, The pH value of the raw material used to prepare the capsule core is in the range of 8 to 9.

7. The method for preparing fire extinguishing microcapsules according to any one of claims 1 to 6, characterized in that, Based on the total mass of the raw materials in the core, the water-based fire extinguishing agent includes 3-6% F500 by mass concentration.

8. The method for preparing fire extinguishing microcapsules according to any one of claims 1 to 6, characterized in that, include: Obtain the raw materials for preparing the capsule core and capsule shell; The raw materials for preparing the capsule core and the raw materials for preparing the capsule shell are injected into the microfluidic device respectively, and microdroplets are formed based on coaxial flow technology or flow focusing technology; The microdroplets were subjected to UV curing and interfacial polymerization to obtain the fire extinguishing microcapsules.

9. The method for preparing fire extinguishing microcapsules according to claim 8, characterized in that, The process of UV curing and interfacial polymerization of the microdroplets to obtain the fire extinguishing microcapsules comprises: The UV light wavelength is 365nm, the power range is 3~10mW / cm2, and the exposure time range is 5~20 seconds; and / or The interfacial polymerization reaction temperature range is 25~60℃, and the interfacial polymerization reaction time is 2~6 hours.

10. The method for preparing fire extinguishing microcapsules according to claim 8, characterized in that, The process involves injecting the raw materials for preparing the capsule core and the raw materials for preparing the capsule shell into a microfluidic device, respectively, and forming microdroplets based on coaxial flow technology or flow focusing technology; including: In the microfluidic device, the flow rate ratio of the raw material for preparing the core to the raw material for preparing the shell is K1, and K1 satisfies: 0.5≤K1≤2.

Images