A perfluorohexanone nanometer microcapsule multiple fire extinguishing tablet and a preparation method thereof

Abstract

The present application relates to a kind of perfluorohexanone nanometer microcapsule multiple fire extinguishing tablets and preparation method thereof, belong to fire extinguishing material processing technical field.The preparation method of perfluorohexanone nanometer microcapsule multiple fire extinguishing tablets disclosed in the present application includes the following steps: (1) preparation of oil phase, standby;(2) preparation of water phase, standby;(3) oil phase and water phase are stirred at high speed, to obtain emulsion;(4) adding initiator monomer in emulsion, temperature preservation, filtration, washing, drying to obtain perfluorohexanone nanometer microcapsule;(5) then mixed with matrix material, introduced into mold curing, drying, and surface is sprayed with high molecular polymer, to obtain perfluorohexanone nanometer microcapsule multiple fire extinguishing tablets.Perfluorohexanone nanometer microcapsule is formed with double-shell structure with lignin-based polyurethane as shell and polyurea / polyurethane composite structure as inner shell, so the perfluorohexanone nanometer microcapsule prepared in the present application has dense and stable capsule wall structure, high embedding rate and excellent fire extinguishing property.

Description

Technical Field

[0001] The invention belongs to the technical field of fire extinguishing material processing and relates to a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet and a preparation method thereof. Background Art

[0002] As my country's electricity consumption and electrical equipment continue to increase, and electricity usage becomes more diverse, the increasingly severe situation of electrical fires demands sufficient attention and preventative measures. Several fire-extinguishing products have been developed to address fires caused by electrical wiring in distribution cabinets. A more mature product is the automatic fire detection and extinguishing system using a fire detector tube. While the fire detector tube can sensitively locate a fire, in practice, a breach in the fire detector tube prevents the extinguishing agent from being accurately sprayed to the fire point, resulting in low effectiveness. A second type of product uses various electronic detectors, such as smoke sensors, ultraviolet flame detectors, and thermal sensors, to detect fires and then activate the fire extinguishing system to extinguish them. However, these products are prone to false alarms and are costly, resulting in less than ideal fire extinguishing results in real-world scenarios.

[0003] Perfluorohexanone is a new type of fluorine-containing fire extinguishing agent that is liquid at room temperature. It has high fire extinguishing efficiency and excellent environmental performance. It is considered to be the most ideal substitute for halon fire extinguishing agent. In view of the characteristics of perfluorohexanone such as non-conductivity, high volatility, and leaving no trace residue after extinguishing the fire, it is very suitable for use in the safety protection of electrical fires. However, due to the fluidity and rapid volatility of perfluorohexanone, it is difficult to form a high coverage of the fire source. Microencapsulation of perfluorohexanone can effectively form a flame retardant material, but the microcapsules are prone to low embedding rate and poor mechanical properties. Therefore, the perfluorohexanone nano-microcapsules provided by the present invention have the characteristics of effectively solidifying and stabilizing perfluorohexanone, a stable preparation process, and a large perfluorohexanone loading capacity. When used, they can form a highly dispersed fire extinguishing effect by being thrown into the fire source. Summary of the Invention

[0004] The present invention relates to a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet and a preparation method thereof, belonging to the technical field of fire extinguishing material processing. The preparation method of the perfluorohexanone nano-microcapsule multiple fire extinguishing tablet disclosed in the present invention comprises the following steps: (1) preparing an oil phase for standby use; (2) preparing an aqueous phase for standby use; (3) stirring the oil phase and the aqueous phase at high speed to obtain an emulsion; (4) adding an initiating monomer to the emulsion, heating and maintaining the temperature, filtering, washing, and drying to obtain perfluorohexanone nano-microcapsules; (5) then mixing with a matrix material, introducing into a mold for curing, drying, and spraying a high molecular weight polymer on the surface to obtain the perfluorohexanone nano-microcapsule multiple fire extinguishing tablet. The perfluorohexanone nano-microcapsules have a double-shell structure formed by using a lignin-based polyurethane as an outer shell and a polyurea / polyurethane composite structure as an inner shell. Therefore, the perfluorohexanone nano-microcapsules prepared by the present invention have a dense and stable capsule wall structure, a high embedding rate, and excellent fire extinguishing properties.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet, the method comprising the following steps:

[0007] (1) perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether are mixed to form an oil phase for standby use;

[0008] (2) dissolving the emulsifier in distilled water to prepare the aqueous phase for later use;

[0009] (3) mixing the oil phase and the water phase and stirring at high speed to obtain an emulsion;

[0010] (4) adding an initiating monomer to the emulsion, heating and maintaining the temperature, filtering, washing the solid with distilled water, and drying to obtain perfluorohexanone nanocapsules;

[0011] (5) The perfluorohexanone nano-microcapsules are mixed with a matrix material, introduced into a mold for curing, dried, and sprayed with a high molecular polymer on the surface to obtain a perfluorohexanone nano-microcapsule multiple fire extinguishing sheet.

[0012] Furthermore, in the step (1), the mass ratio of perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether is 4-6:0.65-0.8:20-30, wherein the pretreated isophorone diisocyanate is prepared by compounding isophorone diisocyanate and modified aluminum hydroxide, and the mass ratio of isophorone diisocyanate to modified aluminum hydroxide is 10-12:0.13-0.15.

[0013] Furthermore, in step (2), the ratio of the emulsifier to distilled water is 10-15 g:30 mL, wherein the emulsifier is composed of linear sodium alkylbenzene sulfonate and a fluorocarbon surfactant in a mass ratio of 1:1.

[0014] Furthermore, in step (3), the volume ratio of the oil phase to the water phase is 1-2:1.5, and the time and speed of the high-speed stirring are 10-20 min and 2000 rpm, respectively.

[0015] Furthermore, in step (4), the ratio of the emulsion to the monomer is 200-250 mL:5-6 g, wherein the monomer is composed of diethylenetriamine, β-cyclodextrin and lignin in a mass ratio of 1:1:2, the heating and holding time and temperature are 2-3 h and 40-50 ° C, respectively, and the drying time and temperature are 10-12 h and 5 ° C, respectively.

[0016] Furthermore, in the step (5), the mass ratio of perfluorohexanone nano-microcapsules to the matrix material is 5-8:2-3, wherein the matrix material refers to a polymer adhesive, the polymer is an acrylic resin, and the spraying thickness is 100-120 μm.

[0017] Furthermore, the preparation method of the modified aluminum hydroxide comprises the following steps:

[0018] A1: Place aluminum hydroxide powder in anhydrous ethanol, stir, and then perform ultrasonic treatment;

[0019] A2: Then add the modifier, continue stirring, and then filter. Wash the solid with distilled water and dry it to obtain modified aluminum hydroxide.

[0020] Furthermore, in step A1, the ratio of aluminum hydroxide powder to anhydrous ethanol is 1 g:15 mL, and the time and temperature of the ultrasonic treatment are 8-10 min and 40-50° C., respectively.

[0021] Furthermore, in step A2, the mass ratio of aluminum hydroxide powder to modifier is 1:0.05-0.2, wherein the modifier is composed of sodium stearate and sodium oleate in a mass ratio of 1:1, the continuous stirring time is 2-3h, and the drying time and temperature are 30-40min and 80°C, respectively.

[0022] Beneficial effects of the present invention:

[0023] The use of two surfactants, linear alkylbenzene sodium sulfonate and fluorocarbon surfactant, improves the emulsification ability, thereby enabling the perfluorohexanone and the polymerization monomer to be evenly dispersed in the emulsion, preparing perfluorohexanone nano-microcapsules of uniform size and improving the embedding rate of the microcapsules;

[0024] The present invention uses sodium stearate and sodium oleate to modify aluminum hydroxide, reducing its polarity and enhancing its compatibility with isophorone diisocyanate. In addition, by introducing modified aluminum hydroxide into the capsule wall, when the microcapsule ruptures, the aluminum hydroxide in the capsule wall absorbs heat and decomposes, thereby playing an auxiliary flame retardant role.

[0025] The perfluorohexanone nano-microcapsules have a double-shell structure with lignin-based polyurethane as the outer shell and a polyurea / polyurethane composite structure as the inner shell, which ensures the embedding rate of perfluorohexanone in the microcapsules. At the same time, the double-shell structure ensures the mechanical stability of the microcapsules. DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0027] The linear alkylbenzene sulfonate in all the embodiments and comparative examples of the present invention was purchased from Runfeng / 25155-30-0, the fluorocarbon surfactant was purchased from CAPSTONE FS-3100 / TF Taifu, the lignin was purchased from Runfeng / 8068-03-9, the polymer adhesive was purchased from Beijing Dongfang / 24937-78-8, the acrylic resin was purchased from Sany Resin, and the aluminum hydroxide powder was purchased from Qiaowei / 006.

[0028] A method for preparing a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet, the method comprising the following steps:

[0029] (1) perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether are mixed to form an oil phase for standby use;

[0030] (2) dissolving the emulsifier in distilled water to prepare the aqueous phase for later use;

[0031] (3) mixing the oil phase and the water phase and stirring at high speed to obtain an emulsion;

[0032] (4) adding an initiating monomer to the emulsion, heating and maintaining the temperature, filtering, washing the solid with distilled water, and drying to obtain perfluorohexanone nanocapsules;

[0033] (5) The perfluorohexanone nano-microcapsules are mixed with a matrix material, introduced into a mold for curing, dried, and sprayed with a high molecular polymer on the surface to obtain a perfluorohexanone nano-microcapsule multiple fire extinguishing sheet.

[0034] In the step (1), the mass ratio of perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether is 4:0.65:20, wherein the pretreated isophorone diisocyanate is prepared by compounding isophorone diisocyanate and modified aluminum hydroxide, and the mass ratio of isophorone diisocyanate to modified aluminum hydroxide is 10:0.13.

[0035] In the step (2), the ratio of the emulsifier to distilled water is 10 g:30 mL, wherein the emulsifier is composed of linear sodium alkylbenzene sulfonate and a fluorocarbon surfactant in a mass ratio of 1:1.

[0036] In step (3), the volume ratio of the oil phase to the water phase is 1:1.5, and the time and speed of the high-speed stirring are 10 min and 2000 rpm, respectively.

[0037] In the step (4), the ratio of the emulsion to the monomer is 200 mL:5 g, wherein the monomer is composed of diethylenetriamine, β-cyclodextrin and lignin in a mass ratio of 1:1:2. The heating and holding time and temperature are 2 h and 40° C., respectively, and the drying time and temperature are 10 h and 5° C., respectively.

[0038] In the step (5), the mass ratio of perfluorohexanone nano-microcapsules to the matrix material is 5:2, wherein the matrix material refers to a polymer adhesive, the polymer is an acrylic resin, and the spraying thickness is 100 μm.

[0039] The preparation method of the modified aluminum hydroxide comprises the following steps:

[0040] A1: Place aluminum hydroxide powder in anhydrous ethanol, stir, and then perform ultrasonic treatment;

[0041] A2: Then add the modifier, continue stirring, and then filter. Wash the solid with distilled water and dry it to obtain modified aluminum hydroxide.

[0042] In step A1, the ratio of aluminum hydroxide powder to anhydrous ethanol is 1 g:15 mL, and the time and temperature of the ultrasonic treatment are 8 min and 40° C., respectively.

[0043] In step A2, the mass ratio of aluminum hydroxide powder to modifier is 1:0.05, wherein the modifier is composed of sodium stearate and sodium oleate in a mass ratio of 1:1. The continuous stirring time is 2 hours, and the drying time and temperature are 30 minutes and 80°C, respectively.

[0044] A method for preparing a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet, the method comprising the following steps:

[0045] (1) perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether are mixed to form an oil phase for standby use;

[0046] (2) dissolving the emulsifier in distilled water to prepare the aqueous phase for later use;

[0047] (3) mixing the oil phase and the water phase and stirring at high speed to obtain an emulsion;

[0048] (4) adding an initiating monomer to the emulsion, heating and maintaining the temperature, filtering, washing the solid with distilled water, and drying to obtain perfluorohexanone nanocapsules;

[0049] (5) The perfluorohexanone nano-microcapsules are mixed with a matrix material, introduced into a mold for curing, dried, and sprayed with a high molecular polymer on the surface to obtain a perfluorohexanone nano-microcapsule multiple fire extinguishing sheet.

[0050] In the step (1), the mass ratio of perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether is 5:0.7:25, wherein the pretreated isophorone diisocyanate is prepared by compounding isophorone diisocyanate and modified aluminum hydroxide, and the mass ratio of isophorone diisocyanate to modified aluminum hydroxide is 11:0.14.

[0051] The ratio of the emulsifier to distilled water in step (2) is 13 g:30 mL, wherein the emulsifier is composed of linear sodium alkylbenzene sulfonate and a fluorocarbon surfactant in a mass ratio of 1:1.

[0052] In step (3), the volume ratio of the oil phase to the water phase is 1:1, and the time and speed of the high-speed stirring are 15 min and 2000 rpm, respectively.

[0053] In the step (4), the ratio of the emulsion to the monomer is 225 mL:5-6 g, wherein the monomer is composed of diethylenetriamine, β-cyclodextrin and lignin in a mass ratio of 1:1:2. The heating and holding time and temperature are 2.5 h and 45 ° C, respectively, and the drying time and temperature are 11 h and 5 ° C, respectively.

[0054] In the step (5), the mass ratio of perfluorohexanone nano-microcapsules to the matrix material is 6:2.5, wherein the matrix material refers to a polymer adhesive, the polymer is an acrylic resin, and the spraying thickness is 110 μm.

[0055] The preparation method of the modified aluminum hydroxide comprises the following steps:

[0056] A1: Place aluminum hydroxide powder in anhydrous ethanol, stir, and then perform ultrasonic treatment;

[0057] A2: Then add the modifier, continue stirring, and then filter. Wash the solid with distilled water and dry it to obtain modified aluminum hydroxide.

[0058] In step A1, the ratio of aluminum hydroxide powder to anhydrous ethanol is 1 g:15 mL, and the time and temperature of the ultrasonic treatment are 9 min and 45° C., respectively.

[0059] The mass ratio of the aluminum hydroxide powder in step A2 to the modifier is 1:0.1, wherein the modifier is composed of sodium stearate and sodium oleate with a mass ratio of 1:1, the time of the continuous stirring is 2.5h, and the time and temperature of the drying are 35min and 80℃ respectively.

[0060] A preparation method of perfluorohexanone nanometer microcapsule multiple fire extinguishing tablets, the preparation method of the fire extinguishing tablets comprising the following steps:

[0061] (1) mixing perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether to form an oil phase, for standby use;

[0062] (2) dissolving an emulsifier in distilled water to prepare an aqueous phase, for standby use;

[0063] (3) mixing the oil phase and the aqueous phase and high-speed stirring to obtain an emulsion;

[0064] (4) adding an initiator monomer to the emulsion, warming and keeping warm, filtering, washing the solid with distilled water, and drying to obtain perfluorohexanone nanometer microcapsules;

[0065] (5) mixing the perfluorohexanone nanometer microcapsules with a matrix material, introducing into a mold for solidification, drying, and spraying a polymer on the surface to obtain perfluorohexanone nanometer microcapsule multiple fire extinguishing tablets.

[0066] In step (1), the mass ratio of perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether is 6:0.8:30, wherein the pretreated isophorone diisocyanate is prepared by compounding isophorone diisocyanate with modified aluminum hydroxide, and the mass ratio of the isophorone diisocyanate to the modified aluminum hydroxide is 12:0.15.

[0067] In step (2), the ratio of the emulsifier to distilled water is 15g:30mL, wherein the emulsifier is composed of sodium linear alkyl benzene sulfonate and fluorocarbon surfactant with a mass ratio of 1:1.

[0068] In step (3), the volume ratio of the oil phase to the aqueous phase is 2:1.5, and the time and speed of the high-speed stirring are 20min and 2000rpm respectively.

[0069] In step (4), the ratio of the emulsion to the monomer is 250mL:6g, wherein the monomer is composed of diethylene triamine, β-cyclodextrin and lignin with a mass ratio of 1:1:2, the time and temperature of the warming and keeping warm are 3h and 50℃ respectively, and the time and temperature of the drying are 12h and 5℃ respectively.

[0070] In the step (5), the mass ratio of perfluorohexanone nano-microcapsules to the matrix material is 8:3, wherein the matrix material refers to a polymer adhesive, the polymer is an acrylic resin, and the spraying thickness is 120 μm.

[0071] The preparation method of the modified aluminum hydroxide comprises the following steps:

[0072] A1: Place aluminum hydroxide powder in anhydrous ethanol, stir, and then perform ultrasonic treatment;

[0073] A2: Then add the modifier, continue stirring, and then filter. Wash the solid with distilled water and dry it to obtain modified aluminum hydroxide.

[0074] In step A1, the ratio of aluminum hydroxide powder to anhydrous ethanol is 1 g:15 mL, and the time and temperature of the ultrasonic treatment are 10 min and 50° C., respectively.

[0075] In step A2, the mass ratio of aluminum hydroxide powder to modifier is 1:0.2, wherein the modifier is composed of sodium stearate and sodium oleate in a mass ratio of 1:1. The continuous stirring time is 3 hours, and the drying time and temperature are 40 minutes and 80°C, respectively.

[0076] Comparative Example 1

[0077] On the basis of Example 2, the linear alkylbenzene sulfonate sodium was removed from the emulsifier, and other conditions were the same as those in Example 2.

[0078] Comparative Example 2

[0079] On the basis of Example 2, the fluorocarbon surfactant in the emulsifier was removed, and other conditions were the same as those in Example 2.

[0080] Comparative Example 3

[0081] On the basis of Example 2, pretreated isophorone diisocyanate was prepared from modified aluminum hydroxide and isophorone diisocyanate, with the modified aluminum hydroxide replaced by aluminum hydroxide powder of equal mass, and other conditions were consistent with Example 2.

[0082] Comparative Example 4

[0083] On the basis of Example 2, the pretreated isophorone diisocyanate was removed and replaced with isophorone diisocyanate of equal mass. Other conditions were the same as those in Example 2.

[0084] Comparative Example 5

[0085] On the basis of Example 2, β-cyclodextrin was removed from the monomer, and other conditions were the same as those in Example 2.

[0086] Comparative Example 6

[0087] On the basis of Example 2, lignin in the monomer was removed, and other conditions were the same as those in Example 2.

[0088] 1. Performance Testing

[0089] Particle size uniformity measurement: The perfluorohexanone nano-microcapsules prepared in Example 2 and Comparative Examples 1-2 were used as samples and the particle size was measured using a laser particle size zeta potential analyzer. Specifically, the sample was diluted 100-fold with distilled water and then injected into a 1 cm × 1 cm × 4.8 cm standard sample cell. Finally, the sample was placed in the laser particle size zeta potential analyzer and scanned 2 to 3 times. The particle size uniformity was recorded and analyzed.

[0090] Determination of embedding efficiency: The perfluorohexanone nano-microcapsules prepared in Example 2, Comparative Examples 1-2, and Comparative Example 5 were used as samples. The total mass of the sample was first weighed, and then the sample was repeatedly ground. An equal amount of chloroform was added to dissolve the core material in the microcapsule. The sample was then placed in an oven at 120°C and dried to a constant weight. The difference between the two values ​​was the mass of the core material of the microcapsule. The specific formula is:

[0091] ;

[0092] Stability test: The perfluorohexanone nano-microcapsules prepared in Example 2 and Comparative Examples 5-6 were used as samples. The microcapsules were placed in a freeze dryer for 12 hours to fully dry and remove surface moisture. After being taken out, they were immediately weighed and then placed in an electric constant temperature drying oven at 100°C for 12 hours. The mass loss rate was obtained by calculating the mass change of the sample. The weight loss formula of the sample was specifically calculated as follows:

[0093] ;

[0094] W L is the mass loss rate, m1 is the original mass of the microcapsules, and m2 is the mass of the microcapsules after drying;

[0095] Fire extinguishing performance test: The perfluorohexanone nano-microcapsule multiple fire extinguishing tablets prepared in Example 2 and Comparative Examples 3-4 were used as samples. An 800°C flame was used as the fire source. The temperature was measured with an infrared thermometer, and the fire extinguishing time was measured with a stopwatch. The sample was fixed on the surface of a stamped steel plate and placed face down 1.5 cm from the outer flame of the flame. The fire extinguishing time at 6 locations of the sample was measured, and the average value was taken to indicate the fire extinguishing performance.

[0096] The above test results are shown in Table 1.

[0097] Table 1 Test results

[0098] Sample Particle size uniformity Embedding rate% Mass loss rate% Fire extinguishing time / s Example 2 Good uniformity 96.7 4.2 1.54 Comparative Example 1 Different sizes 87.3 - - Comparative Example 2 Different sizes 86.1 - - Comparative Example 3 - - - 1.84 Comparative Example 4 - - - 2.07 Comparative Example 5 - 90.4 8.9 - Comparative Example 6 - - 11.3 -

[0099] It can be concluded from Table 1 that Example 2 has good particle size uniformity, the largest embedding rate, the smallest mass loss rate, and the shortest fire extinguishing time. In Comparative Examples 1-2, removing any component of the emulsifier reduces the emulsification effect of the emulsion, affects the surface tension of perfluorohexanone, and thus causes uneven dispersion, resulting in microcapsules of different sizes, and the embedding rate is reduced. In Comparative Example 5, no β-cyclodextrin is added, which also reduces the embedding rate of the microcapsules. The β-cyclodextrin not added in Comparative Example 5 has a reinforcing effect, and in Comparative Example 6, no lignin is added, so the shell structure of the lignin-based polyurethane will not be formed. Therefore, the mechanical properties of the microcapsule wall obtained in Comparative Examples 5-6 are reduced, and the mass loss rate is large. The aluminum hydroxide added in Comparative Example 3 is not modified, and its polarity is large, and its compatibility with isophorone diisocyanate is poor. In Comparative Example 4, no inorganic flame retardant is added, so the fire extinguishing time of Comparative Examples 3-4 is longer than that of Example 2. Since modified aluminum hydroxide is used in Example 2 to reduce its polarity and enhance its compatibility with isophorone diisocyanate, when the microcapsules are ruptured, the aluminum hydroxide in the capsule wall absorbs heat and decomposes, playing an auxiliary flame retardant role.

[0100] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a perfluorohexanone nano-microcapsule multi-use fire extinguishing tablet, characterized in that the method comprises the following steps: (1) perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether are mixed to form an oil phase for standby use; (2) dissolving the emulsifier in distilled water to prepare an aqueous phase for later use; (3) mixing the oil phase and the water phase and stirring at high speed to obtain an emulsion; (4) adding an initiating monomer to the emulsion, heating and maintaining the temperature, filtering, washing the solid with distilled water, and drying to obtain perfluorohexanone nanocapsules; (5) The perfluorohexanone nano-microcapsules are mixed with a matrix material, introduced into a mold for curing, dried, and sprayed with a high molecular polymer on the surface to obtain a perfluorohexanone nano-microcapsule multiple fire extinguishing sheet; In the step (1), the mass ratio of perfluorohexanone, pretreated isophorone diisocyanate and methyl nonafluorobutyl ether is 4-6:0.65-0.8:20-30, wherein the pretreated isophorone diisocyanate is prepared by compounding isophorone diisocyanate and modified aluminum hydroxide, and the mass ratio of isophorone diisocyanate to modified aluminum hydroxide is 10-12:0.13-0.15; In the step (2), the ratio of the emulsifier to distilled water is 10-15 g:30 mL, wherein the emulsifier is composed of linear sodium alkylbenzene sulfonate and a fluorocarbon surfactant in a mass ratio of 1:1; The volume ratio of the oil phase to the water phase in step (3) is 1-2: 1.5, the time and speed of high-speed stirring are 10-20 min and 2000 rpm respectively; In the step (4), the ratio of the emulsion to the monomer is 200-250 mL:5-6 g, wherein the monomer is composed of diethylenetriamine, β-cyclodextrin and lignin in a mass ratio of 1:1:

2. The heating and holding time and temperature are 2-3 hours and 40-50°C, respectively. The drying time and temperature are 10-12 hours and 5°C, respectively.

2. The method for preparing a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet according to claim 1, characterized in that: In the step (5), the mass ratio of perfluorohexanone nano-microcapsules to the matrix material is 5-8:2-3, wherein the matrix material refers to a polymer adhesive, the polymer is an acrylic resin, and the spraying thickness is 100-120 μm.

3. The method for preparing a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet according to claim 1, characterized in that: The preparation method of the modified aluminum hydroxide comprises the following steps: A1: Place aluminum hydroxide powder in anhydrous ethanol, stir, and then perform ultrasonic treatment; A2: Then add the modifier, continue stirring, and then filter. Wash the solid with distilled water and dry it to obtain modified aluminum hydroxide.

4. The method for preparing a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet according to claim 3, characterized in that: In step A1, the ratio of aluminum hydroxide powder to anhydrous ethanol is 1 g:15 mL, and the time and temperature of the ultrasonic treatment are 8-10 min and 40-50° C., respectively.

5. The method for preparing a perfluorohexanone nano-microcapsule multiple fire extinguishing tablet according to claim 3, characterized in that: In step A2, the mass ratio of aluminum hydroxide powder to modifier is 1:0.05-0.2, wherein the modifier is composed of sodium stearate and sodium oleate in a mass ratio of 1:

1. The continuous stirring time is 2-3 hours, and the drying time and temperature are 30-40 minutes and 80°C, respectively.