A nano-capsule fire extinguishing material and its preparation method

Abstract

The present invention belongs to the technical field of fire extinguishing materials, mainly relates to fire extinguishing materials and their preparation methods, and specifically relates to a nano-capsule fire extinguishing material and its preparation method. The present invention uses inexpensive chitosan, modifies it by adding Sc<supgt;3+< / supgt; and Ce<supgt;3+< / supgt>, and uses it as the shell material of the nano-capsule, which can improve the flexibility and ductility of chitosan in the solution, enabling it to encapsulate as much core material as possible. At the same time, under high-temperature conditions, it is beneficial to the release and ejection of the core material. Meanwhile, gelatin solution and gum arabic solution are used as emulsifiers, which can form a stable emulsion with the fire extinguishing agent and coolant used in the core material, facilitating the coating of the modified chitosan. The present invention realizes the solidification loading and large-scale loading of perfluorocyclohexanone, solving the problem that perfluorocyclohexanone is difficult to be made into a fire extinguishing material. Moreover, using perfluorocyclohexanone as the core fire extinguishing medium not only has a low cost, but also does not release harmful substances during the fire extinguishing process, being safe and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of fire extinguishing materials, mainly to fire extinguishing materials and their preparation methods, and specifically to a nano-capsule fire extinguishing material and its preparation method. Background Art

[0002] Fire is one of the disasters in people's daily life. If not extinguished in time, it is likely to cause serious losses to people's lives and property. In theory, all fires can be extinguished. The key lies in extinguishing the fire source in time when the fire breaks out initially, which is the key control factor determining the loss of personnel and property. There are various fire extinguishing media for extinguishing the fire source, and common fire extinguishing media include water, dry ice, etc.

[0003] Microcapsules are tiny capsules formed by coating sensitive or volatile small liquid droplets or solid small particles with polymer materials through certain physical or chemical methods. The solid or liquid substance encapsulated inside the capsule is called the core material or core layer, and the coating film formed by the polymer material is called the wall material or capsule wall. The main functions of microcapsules can be summarized into the following four aspects: (1) Changing the physical properties of the core material: Microcapsules can change the solubility or volatility of the core material. (2) Improving the stability of the core material: After microencapsulating the core material that is sensitive to pH, light, heat, humidity, temperature, oxygen or other substances, it can avoid adverse reactions caused by sensitive factors, so the stability of the core material can be improved; (3) Controlling the release of the core material: The encapsulated core material can be released under certain conditions, and the release process of the core material can be either instantaneous release under certain conditions or slow release under different conditions, so the original efficacy of the core material can be maximally exerted. (4) Isolating components: The microencapsulated core material can isolate components and prevent adverse interference of each component in the core material mixture. As an emerging fire extinguishing medium, microcapsule fire extinguishing agents have been gradually widely used in the fire protection field in recent years. In the prior art, microcapsule active fire extinguishing agents usually use high molecular resin as the shell and encapsulate halogenated hydrocarbon fire extinguishing substances inside (such as Russian Patent RU90994, Chinese Patent CN103370104A, etc.). The halogenated hydrocarbon fire extinguishing substances in the microcapsule core material are not only costly but also have varying degrees of toxicity to the environment and the human body.

[0004] As an important alternative to halon fire extinguishing agents, perfluorohexanone is a compound of fluorinated ketones. In recent years, it has attracted much attention due to its good fire extinguishing ability and the characteristic of not damaging the ozone layer. However, the boiling point of perfluorocarbon compounds is very low, and the boiling point of perfluorohexanone is 49°C, which is easy to quickly vaporize and volatilize, making it difficult to store and apply. Moreover, there is a large immiscibility gap in the solvent systems of perfluorocarbon compounds and hydrocarbon compounds, that is, hydrocarbon liquids and fluorocarbon liquids are immiscible at room temperature, which also greatly increases the difficulty of making perfluorohexanone into a fire extinguishing material. Summary of the Invention

[0005] In view of the above problems, to solve the problems of high cost, environmental unfriendliness of microcapsule fire extinguishing agents in the prior art, and the difficulties in solidifying and loading perfluoropentanone, small loading capacity, difficulty in making fire extinguishing materials, and difficulty in forming a fire source coverage during fire extinguishing, the present invention provides a fire extinguishing nanocapsule material. The fire extinguishing microcapsule core material includes a core material and a shell layer; the core material is coated within the shell layer; the core material is a fluorine-containing fire extinguishing agent; the shell layer material is modified chitosan. The specific operation steps are as follows:

[0006] S1. Preparation of emulsifier: Prepare a gelatin GE solution with a mass fraction of 12 - 21% and an arabic gum GA solution with a mass fraction of 15 - 26% respectively.

[0007] S2. Preparation of Sc / Ce-OH modified chitosan: Add 3 - 5 g of scandium salt and 2 - 4 g of cerium salt to 90 - 130 ml of deionized water, stir for 3 - 5 min, then add 5 - 8 g of chitosan. After ultrasonic treatment for 10 min, add 3 - 5 g of soluble metal hydroxide, stir evenly, and put it into a microwave reaction kettle. After the microwave reaction temperature rises to 108 - 125 °C, maintain this temperature for microwave treatment for 3 - 5 min. After the reaction kettle cools down, wash it with deionized water multiple times, and then perform centrifugal drying to obtain Sc / Ce-OH modified chitosan. Then, prepare a 40% Sc / Ce-OH modified chitosan solution.

[0008] S3. Measure 35 - 45 ml of the gelatin GE solution prepared in step S1, 50 - 80 ml of the modified arabic gum GA solution prepared in step S1, and 40 - 0 ml of the core material solution, and mix them evenly in a three-necked flask.

[0009] S4. Spray the mixed solution prepared in S3 into the 40% Sc / Ce-OH modified chitosan solution prepared in step S2 through a spraying device with a spraying orifice of 3 - 4 mm and a spraying speed of 0.3 - 0.6 L / h, and emulsify at room temperature for 10 - 25 min to form a stable emulsion.

[0010] S5. Slowly drop an acid solution or an alkali solution into the emulsion prepared in step S4 to adjust the system pH value to 6 - 8. After the pH value is stable, raise the system temperature to 80 - 90 °C, add 40 - 50 ml of a curing agent with a concentration of 5%, and carry out a curing reaction for 1 - 2 h to obtain a nanocapsule suspension.

[0011] S6. Centrifuge the nanocapsule suspension, wash, centrifuge, and dry to obtain a nanocapsule fire extinguishing material with a particle size of 50 - 200 nm.

[0012] Preferably: The Sc / Ce-OH modified chitosan consists of chitosan and soluble scandium salt, cerium salt, and metal hydroxide in a mass ratio of 5 - 8:3 - 5:2 - 4:3 - 5.

[0013] Preferably, the core material is a mixed solution of a fire extinguishing agent and a coolant. The fire extinguishing agent includes perfluorohexanone and tetrafluorodibromoethane, and the coolant includes perfluorotriethylamine and difluorotrichloroethane. The mixed solution is formed by mixing perfluorohexanone:tetrafluorodibromoethane:perfluorotriethylamine:difluorotrichloroethane in a volume ratio of 1-4:1-4:0.5-2:0.5-2.

[0014] Preferably, the gelatin GE solution in step S1 is a modified gelatin GE solution, and the gum arabic GA solution is a modified gum arabic GA solution.

[0015] Preparation of P@Cu / MIL-88A: Dissolve 1.36-1.47 g of iron salt and 0.58-0.67 g of terephthalic acid in 40-60 ml of a mixed solvent of DMF:H2O = 1:1, then transfer it to a hydrothermal reactor with a polytetrafluoroethylene lining, and carry out hydrothermal reaction at 60-70 °C for 6-8 h to obtain the catalyst MIL-88A. Then disperse 1.26-1.41 g of MIL-88A and 0.04-0.07 g of copper salt in 30-50 ml of deionized water, ultrasonicate at room temperature for 30 min, discard the supernatant after centrifugation, dry the precipitate at 105 °C to remove moisture, and then reduce the obtained mixture under vacuum conditions at 190-200 °C for 4-5 h to obtain the catalyst Cu / MIL-88A. Then disperse 1-2 g of Cu / MIL-88A in 10-20 ml of a 30% mass fraction of phosphate salt solution, then transfer the solution to a microwave reactor, and continuously react at a set temperature of 50-60 °C and a set power of 80 W for 30 min to obtain phosphated Cu / MIL-88A, that is, the catalyst P@Cu / MIL-88A.

[0016] Preparation of the modified gelatin GE solution: Add 40-50 ml of distilled water to a beaker containing 10-20 g of GE sample, place it in a constant temperature magnetic stirrer, stir to completely dissolve it at a temperature of 55-69 °C, then add NaOH solution to adjust the pH of the GE initial solution to 8-9, and then slowly drop 5-10 ml of an isopropanol solution of 10% mass fraction of sodium trimetaphosphate and 0.1-0.16 g of the P@Cu / MIL-88A, maintain the temperature at 60 °C and react for 20-30 min. During the reaction, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCI solution to adjust the pH value of the reaction system to 5-6. Finally, carry out spray drying, cooling, and then obtain modified gelatin. Then prepare a 15% mass fraction of modified gelatin GE solution.

[0017] Preparation of the modified gum arabic GA solution: Add 43 - 57 ml of distilled water to a beaker containing 15 - 27 g of GA sample, place it in a thermostatic magnetic stirrer, stir to completely dissolve it at a temperature of 52 - 63 °C, then add NaOH solution to adjust the pH of the GA initial solution to 8 - 9, and then slowly drop 6 - 13 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12% and 0.12 - 0.18 g of the P@Cu / MIL - 88A, maintain the temperature at 60 °C and react for 20 - 30 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCI solution to adjust the pH value of the reaction system to 5 - 6; finally, perform spray drying, cool, and then the modified gum arabic can be obtained; then prepare a modified gum arabic GA solution with a mass fraction of 15%.

[0018] Preferably: The iron salt, copper salt, and phosphorus salt are FeCl·6H2O, CuC1·6H2O, and sodium phosphate respectively.

[0019] Preferably: The core material solution in step S3 is a mixed solution of perfluorocyclohexanone, tetrafluorodibromoethane, perfluorotriethylamine, and difluorotrichloroethane in a volume ratio of 1 - 4:1 - 4:0.5 - 2:0.5 - 2.

[0020] Preferably: The acid solution in step S5 is an ice acetic acid solution with a mass fraction of 15 - 35%; the alkali solution is a sodium hydroxide solution with a mass fraction of 7 - 15%; the curing agent is glutaraldehyde with a concentration of 5%.

[0021] Preferably: The cleaning in step S6 is to wash 3 - 5 times with deionized water; the drying is vacuum freeze - drying.

[0022] Preferably: The soluble scandium salt is Sc2(C2O4)3; the soluble cerium salt is Ce(NO3)3·6H2O; the soluble metal hydroxide is LiOH or NaOH.

[0023] Advantages of the present invention:

[0024] 1. Modifying chitosan with Sc 3+ and Ce 3+ simultaneously can improve the ductility and flexibility of chitosan and can achieve maximum encapsulation of the core material;

[0025] 2. The modified gelatin GE solution and the modified gum arabic GA solution can form a more stable emulsion, which is beneficial to the coating of modified chitosan;

[0026] 3. In order to obtain microcapsules with smaller particle sizes, first mix the emulsifier and the core material, and then spray them into the capsule shell solution for emulsification;

[0027] 4. There is a synergistic effect between perfluorohexanone and tetrafluorodibromoethane, which can significantly improve the fire extinguishing performance.

[0028] 5. Adding perfluorotriethylamine and difluorotrichloroethane simultaneously in the fire extinguishing agent has an unexpected synergistic effect and can significantly improve the fire extinguishing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the microcapsules prepared by the present invention.

[0030] Figure 2 Transmission electron microscope image of the nano - capsules prepared in Example 1 of the present invention.

[0031] Figure 3 Scanning electron microscope image of the nano - capsules prepared in Comparative Example 1 of the present invention.

[0032] Figure 4 Scanning electron microscope image of the nano - capsules prepared in Comparative Example 2 of the present invention.

[0033] Figure 5 Transmission microscope image of the nano - capsules prepared in Comparative Example 3 of the present invention.

[0034] Figure 6 Comparison chart of the fire extinguishing performance of Example 3, Comparative Example 4 and Comparative Example 5 prepared by the present invention.

[0035] Figure 7 Comparison chart of the fire extinguishing performance of Example 4, Comparative Example 6 and Comparative Example 7 prepared by the present invention.

[0036] Figure 8 Comparison chart of the emulsifying activity of Example 5, Comparative Examples 8 - 11 prepared by the present invention.

[0037] Figure 9 Comparison chart of the emulsifying stability of Example 5, Comparative Examples 8 - 11 prepared by the present invention.

[0038] Figure 10 Transmission electron microscope image of the micro - capsules prepared in Example 5 of the present invention.

[0039] Figure 11 Transmission electron microscope image of the micro - capsules prepared in Comparative Example 12 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Example 1

[0042] S1. Preparation of modified MIL-88A: Dissolve 1.36 g of FeCl·6H2O and 0.58 g of terephthalic acid in 40 ml of a mixed solvent of DMF:H2O = 1:1, then transfer it to a hydrothermal reactor with a polytetrafluoroethylene liner and carry out hydrothermal reaction at 60 °C for 6 h to obtain the catalyst MIL-88A; then disperse 1.26 g of MIL-88A and 0.04 g of CuC1·6H2O in 30 ml of deionized water, ultrasonicate at room temperature for 30 min, discard the supernatant after centrifugation, dry the precipitate at 105 °C to remove moisture, and then reduce the obtained mixture under vacuum at 190 °C for 4 h to obtain the catalyst Cu / MIL-88A. Then disperse 1 g of Cu / MIL-88A in 10 ml of a sodium phosphate solution with a mass fraction of 30%, transfer the solution to a microwave reactor, and continuously react at a set temperature of 50 °C and a set power of 80 W for 30 min to obtain phosphated Cu / MIL-88A, that is, the catalyst P@Cu / MIL-88A;

[0043] S2. Preparation of modified gelatin: Add 40 ml of distilled water to a beaker containing 10 g of GE sample, place it in a constant-temperature magnetic stirrer, stir at a temperature of 55 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the GE initial solution to 8, then slowly drop 5 ml of an isopropanol solution of sodium trimetaphosphate with a mass fraction of 10% and 0.1 g of P@Cu / MIL-88A prepared in step S1, maintain the temperature at 60 °C and react for 20 min. During the reaction, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCl solution to adjust the pH value of the reaction system to 5; finally, carry out spray drying, cooling, and then obtain modified gelatin; then prepare a modified gelatin solution with a mass fraction of 12%;

[0044] S3. Preparation of modified gum arabic GA: Add 43 ml of distilled water to a beaker containing 15 g of GA sample, place it in a constant-temperature magnetic stirrer, stir at a temperature of 52 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the GA initial solution to 8, then slowly drop 6 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12% and 0.12 g of P@Cu / MIL-88A prepared in step S1, maintain the temperature at 60 °C and react for 20 min. During the reaction, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCl solution to adjust the pH value of the reaction system to 5; finally, carry out spray drying, cooling, and then obtain modified gum arabic; then prepare a modified gum arabic solution with a mass fraction of 15%;

[0045] S4. Preparation of Sc / Ce-OH modified chitosan: Add 3 g of Sc2(C2O4)3 and 2 g of Ce(NO3)3·6H2O into 90 ml of deionized water. After stirring for 3 min, add 5 g of chitosan. After ultrasonic treatment for 10 min, add 3 g of LiOH. After stirring evenly, put it into a microwave reaction kettle. After the microwave reaction temperature rises to 108 °C, maintain this temperature and perform microwave treatment for 3 min. After the reaction kettle cools down, wash it with deionized water multiple times, and then perform centrifugal drying to obtain Sc / Ce-OH modified chitosan. Then, prepare a 40% (by mass) Sc / Ce-OH modified chitosan solution;

[0046] S5. Preparation of the core material of the nano-capsule: The core material uses perfluoromethyl isopropyl ketone as fire extinguishing agent 1 and 1,2-dibromo-1,1,2,2-tetrafluoroethane as fire extinguishing agent 2, perfluoro-triethylamine as coolant 1 and 1,1-dichloro-1,2,2-trifluoroethane as coolant 2; Mix fire extinguishing agent 1, fire extinguishing agent 2, coolant 1 and coolant 2 evenly according to the volume ratio of 1:1:0.5:0.5 to obtain the core material of the fire extinguishing nano-capsule;

[0047] S6. Measure 35 ml of the modified gelatin prepared in step S2, 50 ml of the modified arabic gum prepared in step S3 and 40 ml of the nano-capsule core material solution prepared in step S3 and mix them evenly in a three-necked flask. After mixing evenly, spray them into the 40% (by mass) Sc / Ce-OH modified chitosan solution prepared in step S4 through a spraying device with a spraying orifice of 3 mm and a spraying speed of 0.4 L / h to form a stable emulsion;

[0048] S7. Slowly add a 15% (by mass) glacial acetic acid solution and a 7% (by mass) sodium hydroxide solution to the nano-capsule particles prepared in step S6 to adjust the pH value of the system to 6. After the pH value is stable, raise the temperature of the system to 80 °C, add 40 ml of a 5% (by mass) curing agent, and carry out a curing reaction for 1 h to obtain a nano-capsule suspension;

[0049] S8. Centrifuge the nano-capsule suspension, wash the micro-capsules with deionized water 3 times. After centrifugation, perform vacuum freeze-drying to obtain nano-capsule fire extinguishing materials with a particle size of 50 - 200 nm.

[0050] Comparative Example 1: Except that Sc2(C2O4)3 is not added in step S1, the other steps are the same as those in Example 1.

[0051] Comparative Example 2: Except that Ce(NO3)3·6H2O is not added in step S1, the other steps are the same as those in Example 1.

[0052] Figure 2 This is the transmission microscope image of the nano-capsules prepared in Example 1 of the present invention. It can be seen from the figure that the nano-capsule particles prepared in Example 1 are distinct, with uniform size and a very round appearance.Figure 3 This is the electron scanning microscope image of the nano-capsules prepared in Comparative Example 1 of the present invention. It can be seen from the figure that the particle sizes of the materials are uneven. Figure 4 This is the electron scanning microscope image of the nano-capsules prepared in Comparative Example 2 of the present invention. It can be seen from the figure that there are many wrinkles on the surface of the microspheres, indicating that the microspheres are not filled, which is not conducive to the ejection of the core material of the capsule at high temperatures. In summary, it shows that Sc 3+ and Ce 3+ have a synergistic effect, can effectively modify chitosan, increase the ductility of chitosan in the solution, and enable it to wrap the core material as much as possible.

[0053] Example 2

[0054] S1. Preparation of modified MIL-88A: Dissolve 1.47 g of FeCl·6H2O and 0.67 g of terephthalic acid in 60 ml of a mixed solvent of DMF:H2O = 1:1, and then transfer it to a hydrothermal reactor with a polytetrafluoroethylene inner lining. Carry out hydrothermal reaction at 70 °C for 8 h to obtain the catalyst MIL-88A; then disperse 1.41 g of MIL-88A and 0.07 g of CuC1·6H2O in 50 ml of deionized water, ultrasonically treat for 30 min at room temperature, discard the supernatant after centrifugation, dry the precipitate at 105 °C to remove moisture, and then reduce the obtained mixture under vacuum at 200 °C for 5 h to obtain the catalyst Cu / MIL-88A. Then disperse 2 g of Cu / MIL-88A in 20 ml of a sodium phosphate solution with a mass fraction of 30%, and then transfer the solution to a microwave reactor. React continuously at a set temperature of 60 °C and a set power of 80 W for 30 min to obtain phosphated Cu / MIL-88A, that is, the catalyst P@Cu / MIL-88A;

[0055] S2. Preparation of modified gelatin: Add 50 ml of distilled water to a beaker containing 20 g of GE sample, place it in a constant-temperature magnetic stirrer, stir at a temperature of 69 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the GE initial solution to 9, and then slowly drop 10 ml of an isopropanol solution of sodium trimetaphosphate with a mass fraction of 10% and 0.16 g of P@Cu / MIL-88A prepared in step S1, maintain the temperature at 60 °C and react for 30 min. During the reaction, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCI solution to adjust the pH value of the reaction system to 6; finally, carry out spray drying, cool, and obtain modified gelatin; then prepare a modified gelatin solution with a mass fraction of 17%;

[0056] S3. Preparation of modified gum arabic GA: Add 57 ml of distilled water to a beaker containing 27 g of GA sample, place it in a thermostatic magnetic stirrer, stir at a temperature of 63 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the initial GA solution to 9. Then slowly drop 13 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12% and 0.18 g of P@Cu / MIL-88A prepared in step S1. Maintain the temperature at 60 °C and react for 30 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCl solution to adjust the pH value of the reaction system to 6; finally, perform spray drying, cool, and then the modified gum arabic can be obtained; then prepare a modified gum arabic solution with a mass fraction of 19%;

[0057] S4. Preparation of Sc / Ce-OH modified chitosan: Add 5 g of Sc2(C2O4)3 and 4 g of Ce(NO3)3·6H2O to 130 ml of deionized water, stir for 5 min, then add 8 g of chitosan, after ultrasonic treatment for 10 min, add 5 g of NaOH, stir evenly, and then put it into a microwave reaction kettle. After the microwave reaction temperature rises to 125 °C, maintain this temperature and perform microwave treatment for 5 min. After the reaction kettle cools down, wash it with deionized water multiple times, and then perform centrifugal drying to obtain Sc / Ce-OH modified chitosan, and then prepare a Sc / Ce-OH modified chitosan solution with a mass of 40%;

[0058] S5. Preparation of the core material of the nanocapsule: The core material uses perfluoromethyl isopropyl ketone as fire extinguishing agent 1 and 1,2-dibromo-1,1,2,2-tetrafluoroethane as fire extinguishing agent 2, perfluorotriethylamine as coolant 1 and 1,1-dichloro-1,2,2-trifluoroethane as coolant 2; Mix fire extinguishing agent 1, fire extinguishing agent 2, coolant 1 and coolant 2 evenly according to a volume ratio of 2:1:0.5:1 to obtain the core material of the fire extinguishing nanocapsule;

[0059] S6. Measure 35 ml of the modified gelatin prepared in step S2, 80 ml of the modified gum arabic prepared in step S3 and 50 ml of the nanocapsule core material solution prepared in step S3 and mix them evenly in a three-necked flask. After mixing evenly, spray them into the 40% Sc / Ce-OH modified chitosan solution prepared in step S4 through a spraying device with a spray orifice of 3.3 mm and a spraying speed of 0.6 L / h to form a stable emulsion;

[0060] S7. Slowly drop a 19% acetic acid solution and an 8% sodium hydroxide solution with a mass fraction into the nanocapsule particles prepared in step S6 to adjust the pH value of the system to 7. After the pH value is stable, raise the temperature of the system to 90 °C, add 50 ml of a curing agent with a concentration of 5%, and carry out a curing reaction for 2 h to obtain a nanocapsule suspension;

[0061] S8. Centrifuge the nano-capsule suspension, wash the micro-capsules 5 times with deionized water. After centrifugation, vacuum freeze-dry to obtain nano-capsule fire extinguishing materials with a particle size of 50 - 200 nm.

[0062] Comparative Example 3: Replace the chitosan in step S4 with cellulose, and keep the other steps the same as in Example 2.

[0063] Figure 5 This is the transmission microscope image of the nano-capsules prepared in Comparative Example 3 of the present invention. It can be seen from the figure that the degree of adhesion between the shells prepared using cellulose is very large, which is not conducive to the ejection of the core material of the capsule at high temperatures and will seriously affect the fire extinguishing performance.

[0064] Example 3

[0065] S1. Preparation of modified MIL-88A: Dissolve 1.37 g of FeCl·6H2O and 0.61 g of terephthalic acid in 50 ml of a mixed solvent of DMF:H2O = 1:1, then transfer it to a hydrothermal reactor with a polytetrafluoroethylene inner liner, and carry out hydrothermal reaction at 65 °C for 6.5 h to obtain the catalyst MIL-88A; then disperse 1.28 g of MIL-88A and 0.05 g of CuC1·6H2O in 37 ml of deionized water, ultrasonicate at room temperature for 30 min, discard the supernatant after centrifugation, dry the precipitate at 105 °C to remove moisture, and then reduce the obtained mixture under vacuum at 197 °C for 4.5 h to obtain the catalyst Cu / MIL-88A. Then disperse 1 - 2 g of Cu / MIL-88A in 15 ml of a sodium phosphate solution with a mass fraction of 30%, then transfer the solution to a microwave reactor, and continuously react at a set temperature of 55 °C and a set power of 80 W for 30 min to obtain phosphated Cu / MIL-88A, that is, the catalyst P@Cu / MIL-88A;

[0066] S2. Preparation of modified gelatin: Add 43 ml of distilled water to a beaker containing 12 g of GE sample, place it in a constant temperature magnetic stirrer, stir at a temperature of 59 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the GE initial solution to 8.3, and then slowly drop 7 ml of an isopropanol solution of sodium trimetaphosphate with a mass fraction of 10% and 0.14 g of P@Cu / MIL-88A prepared in step S1, maintain the temperature at 60 °C and react for 205 min. During the reaction, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCI solution to adjust the pH value of the reaction system to 5.5; finally, carry out spray drying, cool, and obtain modified gelatin; then prepare a modified gelatin solution with a mass fraction of 18%;

[0067] S3. Preparation of Modified Gum Arabic GA: Add 47 ml of distilled water to a beaker containing 17 g of GA sample, place it in a constant-temperature magnetic stirrer, stir at a temperature of 56 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the GA initial solution to 8.6. Then slowly drop 8 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12% and 0.14 g of P@Cu / MIL-88A prepared in step S1. Maintain the temperature at 60 °C and react for 25 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCl solution to adjust the pH value of the reaction system to 5.5; finally, perform spray drying, cool, and then the modified gum arabic can be obtained; then prepare a modified gum arabic solution with a mass fraction of 26%.

[0068] S4. Preparation of Sc / Ce-OH Modified Chitosan: Add 3.7 g of Sc2(C2O4)3 and 2.8 g of Ce(NO3)3·6H2O to 93 ml of deionized water, stir for 3 min, then add 5.9 g of chitosan, after ultrasonic treatment for 10 min, add 3.6 g of LiOH, stir evenly, and then put it into a microwave reaction kettle. After the microwave reaction temperature rises to 118 °C, maintain this temperature and perform microwave treatment for 3 min. After the reaction kettle cools down, wash it with deionized water multiple times, and then perform centrifugal drying to obtain Sc / Ce-OH modified chitosan, and then prepare a Sc / Ce-OH modified chitosan solution with a mass of 40%.

[0069] S5. Preparation of Nano-Capsule Core Material: The core material uses perfluoromethyl isopropyl ketone as fire extinguishing agent 1 and 1,2-dibromo-1,1,2,2-tetrafluoroethane as fire extinguishing agent 2, perfluorotriethylamine as coolant 1 and 1,1-dichloro-1,2,2-trifluoroethane as coolant 2; mix fire extinguishing agent 1, fire extinguishing agent 2, coolant 1 and coolant 2 evenly according to a volume ratio of 2:1:1:2 to obtain the fire extinguishing nano-capsule core material.

[0070] S6. Measure 38 ml of the modified gelatin prepared in step S2, 57 ml of the modified gum arabic prepared in step S3 and 49 ml of the nano-capsule core material solution prepared in step S3 and mix them evenly in a three-necked flask. After mixing evenly, spray them into the 40% Sc / Ce-OH modified chitosan solution prepared in step S4 through a spraying device with a spraying orifice of 3.5 mm and a spraying speed of 0.5 L / h to form a stable emulsion.

[0071] S7. Slowly drop a 20% glacial acetic acid solution and a 9% sodium hydroxide solution into the nano-capsule particles prepared in step S6 to adjust the pH value of the system to 6.7. After the pH value is stable, raise the temperature of the system to 88 °C, add 45 ml of a curing agent with a concentration of 5%, and after curing reaction for 1 h, obtain a nano-capsule suspension.

[0072] S8. Centrifuge the nano - capsule suspension, wash the micro - capsules 4 times with deionized water. After centrifugation, vacuum freeze - dry to obtain nano - capsule fire - extinguishing materials with a particle size of 50 - 200 nm.

[0073] Comparative Example 4: Except that fire - extinguishing agent 1 is not used in step S5, the rest of the steps are the same as those in Example 3.

[0074] Comparative Example 5: Except that fire - extinguishing agent 2 is not used in step S5, the rest of the steps are the same as those in Example 3.

[0075] Figure 6 This is the comparison chart of the fire - extinguishing performance of Example 3, Comparative Example 4, and Comparative Example 5 prepared by the present invention. According to Figure 6 It can be seen that not using fire - extinguishing agent 1, i.e., perfluorohexanone, or not using fire - extinguishing agent 2, i.e., 1,2 - dibromo - 1,1,2,2 - tetrafluoroethane, will significantly reduce the fire - extinguishing performance. It shows that there is a synergistic effect between perfluorohexanone and 1,2 - dibromo - 1,1,2,2 - tetrafluoroethane, which can significantly improve the fire - extinguishing performance.

[0076] Example 4

[0077] S1. Preparation of modified MIL - 88A: Dissolve 1.44 g of FeCl·6H2O and 0.64 g of terephthalic acid in 46 ml of a mixed solvent of DMF:H2O = 1:1, then transfer it to a hydrothermal reactor with a polytetrafluoroethylene liner, and carry out hydrothermal reaction at 67 °C for 7 h to obtain the catalyst MIL - 88A; then disperse 1.39 g of MIL - 88A and 0.05 g of CuC1·6H2O in 33 ml of deionized water, ultrasonicate at room temperature for 30 min, centrifuge and discard the supernatant, dry the precipitate at 105 °C to remove water, and then reduce the obtained mixture under vacuum at 197 °C for 4.5 h to obtain the catalyst Cu / MIL - 88A. Then disperse 1.8 g of Cu / MIL - 88A in 14 ml of a sodium phosphate solution with a mass fraction of 30%, then transfer the solution to a microwave reactor, and continuously react at a set temperature of 56 °C and a set power of 80 W for 30 min to obtain phosphated Cu / MIL - 88A, that is, the catalyst P@Cu / MIL - 88A;

[0078] S2. Preparation of modified gelatin: Add 49 ml of distilled water to a beaker containing 14 g of GE sample, place it in a constant-temperature magnetic stirrer, stir at 56 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the initial GE solution to 8.8, and then slowly drop 7 ml of an isopropanol solution of sodium trimetaphosphate with a mass fraction of 10% and 0.15 g of P@Cu / MIL-88A prepared in step S1. Maintain the temperature at 60 °C and react for 23 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCl solution to adjust the pH value of the reaction system to 5.6; finally, perform spray drying, cool, and then the modified gelatin can be obtained; then prepare a modified gelatin solution with a mass fraction of 21%.

[0079] S3. Preparation of modified gum arabic GA: Add 45 ml of distilled water to a beaker containing 22 g of GA sample, place it in a constant-temperature magnetic stirrer, stir at 61 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the initial GA solution to 8.9, and then slowly drop 11 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12% and 0.13 g of P@Cu / MIL-88A prepared in step S1. Maintain the temperature at 60 °C and react for 22 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCl solution to adjust the pH value of the reaction system to 5.6; finally, perform spray drying, cool, and then the modified gum arabic can be obtained; then prepare a modified gum arabic solution with a mass fraction of 23%.

[0080] S4. Preparation of Sc / Ce-OH modified chitosan: Add 4.5 g of Sc2(C2O4)3 and 3.5 g of Ce(NO3)3·6H2O to 100 ml of deionized water, stir for 4 min, then add 7 g of chitosan, after ultrasonic treatment for 10 min, add 4.3 g of LiOH, stir evenly, and put it into a microwave reaction kettle. After the microwave reaction temperature rises to 120 °C, maintain this temperature and perform microwave treatment for 5 min. After the reaction kettle cools down, wash it with deionized water multiple times, and then perform centrifugal drying to obtain Sc / Ce-OH modified chitosan, and then prepare a Sc / Ce-OH modified chitosan solution with a mass of 40%.

[0081] S5. Preparation of nano-capsule core material: The core material uses perfluoromethyl isopropyl ketone as fire extinguishing agent 1 and 1,2-dibromo-1,1,2,2-tetrafluoroethane as fire extinguishing agent 2, perfluorotriethylamine as coolant 1 and 1,1-dichloro-1,2,2-trifluoroethane as coolant 2; Mix fire extinguishing agent 1, fire extinguishing agent 2, coolant 1 and coolant 2 evenly according to a volume ratio of 4:3:1:2 to obtain the fire extinguishing nano-capsule core material.

[0082] S6. Measure 40 ml of the modified gelatin prepared in step S2, 70 ml of the modified gum arabic prepared in step S3, and 41 ml of the nano-capsule core material solution prepared in step S3, mix them evenly in a three-necked flask. After mixing evenly, spray them into the Sc / Ce-OH modified chitosan solution with a mass fraction of 40% prepared in step S4 through a spraying device with a spraying orifice of 4 mm and a spraying speed of 0.6 L / h to form a stable emulsion;

[0083] S7. Slowly drop the glacial acetic acid solution with a mass fraction of 22% and the sodium hydroxide solution with a mass fraction of 10% into the nano-capsule particles prepared in step S6 to adjust the pH value of the system to 6.8. After the pH value is stable, raise the temperature of the system to 89 °C, add 45 ml of a curing agent with a concentration of 5%, and obtain a nano-capsule suspension after 1 h of curing reaction;

[0084] S8. Centrifuge the nano-capsule suspension, wash the micro-capsules 5 times with deionized water. After centrifugation, vacuum freeze-dry to obtain nano-capsule fire extinguishing materials with a particle size of 50 - 200 nm.

[0085] Comparative example 6: Except that coolant 1 is not added in step S5, the other steps are the same as those in Example 4.

[0086] Comparative example 7: Except that coolant 2 is not added in step S5, the other steps are the same as those in Example 4.

[0087] Figure 7 This is the fire extinguishing performance comparison chart of Example 4, Comparative example 6 and Comparative example 7 prepared by the present invention. According to Figure 7 It can be seen that the addition of the coolant plays a crucial role in fire extinguishing, and the simultaneous use of coolant 1, i.e., perfluorotriethylamine, and coolant 2, i.e., difluorotrichloroethane, has an unexpected synergistic effect and can significantly improve the fire extinguishing performance.

[0088] Example 5

[0089] S1. Preparation of modified MIL-88A: Dissolve 1.47 g of FeCl·6H₂O and 0.67 g of terephthalic acid in 60 ml of a mixed solvent of DMF:H₂O = 1:1, then transfer it to a hydrothermal reactor with a polytetrafluoroethylene liner and carry out hydrothermal reaction at 60 °C for 8 h to obtain the catalyst MIL-88A; then disperse 1.26 g of MIL-88A and 0.07 g of CuC1·6H₂O in 30 ml of deionized water, ultrasonicate for 30 min at room temperature, discard the supernatant after centrifugation, dry the precipitate at 105 °C to remove water, and then reduce the obtained mixture under vacuum at 190 °C for 4 h to obtain the catalyst Cu / MIL-88A. Then disperse 2 g of Cu / MIL-88A in 10 ml of a sodium phosphate solution with a mass fraction of 30%, transfer the solution to a microwave reactor, and continuously react at a set temperature of 56 °C and a set power of 80 W for 30 min to obtain phosphated Cu / MIL-88A, that is, the catalyst P@Cu / MIL-88A;

[0090] S2. Preparation of modified gelatin: Add 40 ml of distilled water to a beaker containing 20 g of GE sample, place it in a constant-temperature magnetic stirrer, stir at a temperature of 69 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the GE initial solution to 8, then slowly drop 10 ml of an isopropanol solution of sodium trimetaphosphate with a mass fraction of 10%, and 0.1 g of P@Cu / MIL-88A prepared in step S1, maintain the temperature at 60 °C and react for 30 min. During the reaction, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCI solution to adjust the pH value of the reaction system to 5; finally, carry out spray drying, cooling, and then obtain modified gelatin; then prepare a modified gelatin solution with a mass fraction of 19%;

[0091] S3. Preparation of modified gum arabic GA: Add 43 ml of distilled water to a beaker containing 27 g of GA sample, place it in a constant-temperature magnetic stirrer, stir at a temperature of 63 °C until it is completely dissolved, then add NaOH solution to adjust the pH of the GA initial solution to 8, then slowly drop 13 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12%, and 0.12 g of P@Cu / MIL-88A prepared in step S1, maintain the temperature at 60 °C and react for 30 min. During the reaction, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCI solution to adjust the pH value of the reaction system to 5; finally, carry out spray drying, cooling, and then obtain modified gum arabic; then prepare a modified gum arabic solution with a mass fraction of 25%;

[0092] S4. Preparation of Sc / Ce-OH modified chitosan: Add 5 g of Sc2(C2O4)3 and 2 g of Ce(NO3)3·6H2O into 93 ml of deionized water. After stirring for 5 min, add 5 g of chitosan. After ultrasonic treatment for 10 min, add 4 g of NaOH. After stirring evenly, put it into a microwave reaction kettle. After the microwave reaction temperature rises to 125 °C, maintain this temperature and microwave-treat for 5 min. After the reaction kettle cools down, wash it with deionized water for multiple times, and then carry out centrifugal drying to obtain Sc / Ce-OH modified chitosan. Then, prepare a 40% mass Sc / Ce-OH modified chitosan solution;

[0093] S5. Preparation of nano-capsule core material: The core material uses perfluoromethyl isopropyl ketone as fire extinguishing agent 1 and 1,2-dibromo-1,1,2,2-tetrafluoroethane as fire extinguishing agent 2, perfluorotriethylamine as coolant 1 and 1,1-dichloro-1,2,2-trifluoroethane as coolant 2; Mix fire extinguishing agent 1, fire extinguishing agent 2, coolant 1 and coolant 2 evenly according to the volume ratio of 4:1:2:1 to obtain the fire extinguishing nano-capsule core material;

[0094] S6. Measure 45 ml of the modified gelatin prepared in step S2, 50 ml of the modified arabic gum prepared in step S3 and 50 ml of the nano-capsule core material solution prepared in step S3 and mix them evenly in a three-necked flask. After mixing evenly, spray them into the 40% mass Sc / Ce-OH modified chitosan solution prepared in step S4 through a spraying device with a spraying port of 4 mm and a spraying speed of 0.4 L / h to form a stable emulsion;

[0095] S7. Slowly drop a 30% mass acetic acid solution and a 14% mass sodium hydroxide solution into the nano-capsule particles prepared in step S6 to adjust the system pH value = 7. After the pH value is stable, raise the system temperature to 90 °C, add 40 ml of a 5% curing agent, and carry out curing reaction for 1.5 h to obtain a nano-capsule suspension;

[0096] S8. Centrifuge the nano-capsule suspension, wash the micro-capsules with deionized water for 4 times. After centrifugation, carry out vacuum freeze-drying to obtain nano-capsule fire extinguishing materials with particle sizes of 50 - 200 nm.

[0097] Comparative example 8: Except that the modified gelatin prepared in the present invention is replaced with unmodified gelatin in step S6, the other steps are the same as those in Example 5.

[0098] Comparative example 9: Except that the modified arabic gum prepared in the present invention is replaced with unmodified arabic gum in step S6, the other steps are the same as those in Example 5.

[0099] Comparative example 10: Except that modified arabic gum is not used in step S6, the other steps are the same as those in Example 5.

[0100] Comparative Example 11: Except that modified gelatin is not used in step S6, the remaining steps are the same as those in Example 5.

[0101] Comparative Example 12: Except that the spraying method is not used in step S6, the remaining steps are the same as those in Example 5.

[0102] Figure 8 and Figure 9 are the comparison charts of the emulsifying activity and emulsifying stability during the emulsification process. From Figure 8 and Figure 9 it can be seen that the emulsifying activity and emulsifying stability of unmodified gelatin and gum arabic are significantly reduced, indicating that the emulsifying activity of the modified gelatin and modified gum arabic prepared by the present invention is significantly improved, and the stability is also greatly improved after forming the emulsion. According to the emulsifying activity and emulsifying stability of Comparative Example 9 and Comparative Example 10, it can be known that there is an unexpected synergistic effect between the modified gelatin and modified gum arabic prepared by the present invention, which can improve the emulsifying performance. Figure 10 is the transmission electron micrograph of the nano microcapsules prepared in Example 5 of the present invention. It can be seen that the microcapsules are uniform in size, and the particle size is about 100 nm. At the same time, compared with the microcapsules prepared in Example 1, the particle size is relatively larger, indicating that the size of the nozzle and the spraying speed will also affect the size of the microcapsule particles. Figure 11 is the transmission electron micrograph of the nano capsules prepared in Comparative Example 12 of the present invention. It can be known that the particle size of the nano capsules prepared without using the spraying method is relatively large and uneven.

[0103] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only the preferred examples of the present invention, and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A nano - capsule fire - extinguishing material, characterized in that: It includes a capsule wall and a core material wrapped in the capsule wall, and the material of the capsule wall is Sc / Ce-OH modified chitosan; Among them, Sc / Ce-OH modified chitosan is composed of chitosan, soluble scandium salt, cerium salt, and metal hydroxide with a mass ratio of 5-8:3-5:2-4:3-5; The preparation method of the nano-capsule fire extinguishing material includes the following steps: S1. Preparation of P@Cu / MIL-88A: Dissolve 1.36-1.47 g of iron salt and 0.58-0.67 g of terephthalic acid in 40-60 ml of a mixed solvent of DMF:H2O = 1:1, then transfer it to a hydrothermal reactor with a polytetrafluoroethylene liner, and carry out hydrothermal reaction at 60-70 °C for 6-8 h to obtain the catalyst MIL-88A; then disperse 1.26-1.41 g of MIL-88A and 0.04-0.07 g of copper salt into 30-50 ml of deionized water, ultrasonically treat for 30 min at room temperature, discard the supernatant after centrifugation, dry the precipitate at 105 °C to remove moisture, and then reduce the obtained mixture under vacuum conditions at 190-200 °C for 4-5 h to obtain the catalyst Cu / MIL-88A. Then disperse 1-2 g of Cu / MIL-88A into 10-20 ml of a phosphate salt solution with a mass fraction of 30%, then transfer the solution to a microwave reactor, and continuously react at a set temperature of 50-60 °C and a set power of 80 W for 30 min to obtain phosphated Cu / MIL-88A, that is, the catalyst P@Cu / MIL-88A; S2. Preparation of modified gelatin GE solution: Add 40-50 ml of distilled water to a beaker containing 10-20 g of GE sample, place it in a constant temperature magnetic stirrer, stir to completely dissolve it at a temperature of 55-69 °C, then add NaOH solution to adjust the pH value of the initial GE solution to 8-9, and then slowly drop 5-10 ml of an isopropanol solution of sodium trimetaphosphate with a mass fraction of 10% and 0.1-0.16 g of the P@Cu / MIL-88A, maintain the temperature at 60 °C and react for 20-30 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCL solution to adjust the pH value of the reaction system to 5-6; finally, carry out spray drying, cooling, and then the modified gelatin can be obtained; then prepare a modified gelatin GE solution with a mass fraction of 12-21%; S3. Preparation of modified gum arabic GA solution: Add 43 - 57 ml of distilled water to a beaker containing 15 - 27 g of GA sample, place it in a constant temperature magnetic stirrer, stir to completely dissolve it at a temperature of 52 - 63 °C, then add NaOH solution to adjust the pH value of the initial GA solution to 8 - 9. Then slowly drop 6 - 13 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12% and 0.12 - 0.18 g of the P@Cu / MIL - 88A, maintain the temperature at 60 °C and react for 20 - 30 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCL solution to adjust the pH value of the reaction system to 5 - 6; finally, perform spray drying, cool, and then the modified gum arabic can be obtained; then prepare a modified gum arabic GA solution with a mass fraction of 15 - 26%; S4. Preparation of Sc / Ce - OH modified chitosan: Add 3 - 5 g of scandium salt and 2 - 4 g of cerium salt to 90 - 130 ml of deionized water, stir for 3 - 5 min, then add 5 - 8 g of chitosan. After ultrasonic treatment for 10 min, add 3 - 5 g of soluble metal hydroxide, stir evenly, and then put it into a microwave reaction kettle. After the microwave reaction temperature rises to 108 - 125 °C, maintain this temperature and perform microwave treatment for 3 - 5 min. After the reaction kettle cools down, wash it with deionized water multiple times, and then perform centrifugal drying to obtain Sc / Ce - OH modified chitosan, and then prepare a Sc / Ce - OH modified chitosan solution with a mass of 40%; S5. Measure 35 - 45 ml of the modified gelatin GE solution prepared in step S2, 50 - 80 ml of the modified gum arabic GA solution prepared in step S3 and 40 - 50 ml of the core material solution and mix them evenly in a three - necked flask. The core material is a mixed solution of a fire extinguishing agent and a coolant. The fire extinguishing agent includes perfluoromethylcyclohexanone and 1,2 - dibromo - 1,1,2,2 - tetrafluoroethane, and the coolant includes perfluorotriethylamine and 1,1 - dichloro - 1,2,2 - trifluoroethane; the mixed solution is composed of a mixture of perfluoromethylcyclohexanone:1,2 - dibromo - 1,1,2,2 - tetrafluoroethane:perfluorotriethylamine:1,1 - dichloro - 1,2,2 - trifluoroethane in a volume ratio of 1 - 4:1 - 4:0.5 - 2:0.5 - 2; S6. Spray the mixed solution prepared in S5 into the 40% Sc / Ce - OH modified chitosan solution prepared in step S4 through a spraying device with a spray nozzle diameter of 3 - 4 mm and a spraying speed of 0.3 - 0.6 L / h, and emulsify at room temperature for 10 - 25 min to form a stable emulsion; S7. Slowly drop an acid solution or an alkali solution into the emulsion prepared in step S6 to adjust the system pH value to 6 - 8. After the pH value is stable, raise the system temperature to 80 - 90 °C, add 40 - 50 ml of a curing agent with a concentration of 5%, and carry out a curing reaction for 1 - 2 h to obtain a nano - capsule suspension; S8. Centrifuge the nano - capsule suspension, wash, centrifuge, and dry to obtain a nano - capsule fire - extinguishing material with a particle size of 50 - 200 nm.

2. The nano-capsule fire extinguishing material according to claim 1, wherein: The soluble scandium salt is Sc2(C2O4)3; the soluble cerium salt is Ce(NO3)3∙6H2O; the soluble metal hydroxide is LiOH or NaOH.

3. A preparation method of a nano-capsule fire extinguishing material, characterized in that: The specific operation steps are as follows: S1. Preparation of P@Cu / MIL-88A: Dissolve 1.36 - 1.47 g of iron salt and 0.58 - 0.67 g of terephthalic acid in 40 - 60 ml of a mixed solvent of DMF:H2O = 1:1, then transfer it to a hydrothermal reactor with a polytetrafluoroethylene inner liner, and carry out hydrothermal reaction at 60 - 70 °C for 6 - 8 h to obtain the catalyst MIL-88A; then disperse 1.26 - 1.41 g of MIL-88A and 0.04 - 0.07 g of copper salt in 30 - 50 ml of deionized water, ultrasonicate at room temperature for 30 min, centrifuge and discard the supernatant, dry the precipitate at 105 °C to remove water, then reduce the obtained mixture under vacuum conditions at 190 - 200 °C for 4 - 5 h to obtain the catalyst Cu / MIL-88A, then disperse 1 - 2 g of Cu / MIL-88A in 10 - 20 ml of a 30% mass fraction of phosphate salt solution, then transfer the solution to a microwave reactor, and continuously react at a set temperature of 50 - 60 °C and a set power of 80 W for 30 min to obtain the phosphated Cu / MIL-88A, that is, the catalyst P@Cu / MIL-88A; S2. Preparation of modified gelatin GE solution: Add 40 - 50 ml of distilled water to a beaker containing 10 - 20 g of GE sample, place it in a constant temperature magnetic stirrer, stir to completely dissolve it at a temperature of 55 - 69 °C, then add NaOH solution to adjust the pH value of the initial GE solution to 8 - 9, then slowly drop 5 - 10 ml of an isopropanol solution of 10% mass fraction of sodium trimetaphosphate and 0.1 - 0.16 g of the said P@Cu / MIL-88A, maintain the temperature at 60 °C and react for 20 - 30 min, use NaOH solution to maintain the pH value of the reaction system during the reaction, and adjust the pH value of the reaction system to 5 - 6 with HCL solution after the reaction is completed; finally, carry out spray drying, cool, and obtain the modified gelatin; then prepare a modified gelatin GE solution with a mass fraction of 12 - 21%. S3. Preparation of modified gum arabic GA solution: Add 43 - 57 ml of distilled water to a beaker containing 15 - 27 g of GA sample, place it in a constant-temperature magnetic stirrer, stir to completely dissolve it at a temperature of 52 - 63 °C, then add NaOH solution to adjust the pH value of the initial GA solution to 8 - 9. Then slowly drop 6 - 13 ml of a cyclohexane solution of dodecenyl succinic anhydride with a mass fraction of 12% and 0.12 - 0.18 g of the P@Cu / MIL-88A, maintain the temperature at 60 °C and react for 20 - 30 min. During the reaction process, use NaOH solution to maintain the pH value of the reaction system. After the reaction is completed, use HCl solution to adjust the pH value of the reaction system to 5 - 6; finally, perform spray drying, cool, and then the modified gum arabic can be obtained; then prepare a modified gum arabic GA solution with a mass fraction of 15 - 26%. S4. Preparation of Sc / Ce-OH modified chitosan: Add 3 - 5 g of scandium salt and 2 - 4 g of cerium salt to 90 - 130 ml of deionized water, stir for 3 - 5 min, then add 5 - 8 g of chitosan. After ultrasonic treatment for 10 min, add 3 - 5 g of soluble metal hydroxide, stir evenly, and put it into a microwave reaction kettle. After the microwave reaction temperature rises to 108 - 125 °C, maintain this temperature and perform microwave treatment for 3 - 5 min. After the reaction kettle cools, wash it with deionized water multiple times, and then perform centrifugal drying to obtain Sc / Ce-OH modified chitosan, and then prepare a Sc / Ce-OH modified chitosan solution with a mass of 40%. S5. Measure 35 - 45 ml of the modified gelatin GE solution prepared in step S2, 50 - 80 ml of the modified gum arabic GA solution prepared in step S3 and 40 - 50 ml of the core material solution into a three-necked flask and mix evenly. The core material is a mixed solution of a fire extinguishing agent and a coolant. The fire extinguishing agent includes perfluorohexanone and tetrafluorodibromoethane, and the coolant includes perfluorotriethylamine and difluorotrichloroethane; the mixed solution is composed of a mixture of perfluorohexanone:tetrafluorodibromoethane:perfluorotriethylamine:difluorotrichloroethane in a volume ratio of 1 - 4:1 - 4:0.5 - 2:0.5 - 2. S6. Spray the mixed solution prepared in S5 into the 40% Sc / Ce-OH modified chitosan solution prepared in step S4 through a spraying device with a spraying orifice of 3 - 4 mm and a spraying speed of 0.3 - 0.6 L / h, and emulsify at room temperature for 10 - 25 min to form a stable emulsion. S7. Slowly drop an acid solution or an alkali solution into the emulsion prepared in step S6 to adjust the system pH value to 6 - 8. After the pH value is stable, raise the system temperature to 80 - 90 °C, add 40 - 50 ml of a curing agent with a concentration of 5%, and carry out a curing reaction for 1 - 2 h to obtain a nano-capsule suspension. S8. Centrifuge the nano-capsule suspension, wash, centrifuge, and dry to obtain nano-capsule fire extinguishing materials with a particle size of 50 - 200 nm.

4. The preparation method of a nano-capsule fire extinguishing material according to claim 3, characterized in that: The soluble scandium salt is Sc2(C2O4)3; the soluble cerium salt is Ce(NO3)3∙6H2O; the soluble metal hydroxide is LiOH or NaOH.

5. The preparation method of a nano-capsule fire extinguishing material according to claim 3, characterized in that: The acid solution in step S7 is a glacial acetic acid solution with a mass fraction of 15 - 35%; the alkali solution is a sodium hydroxide solution with a mass fraction of 7 - 15%; the curing agent is glutaraldehyde with a concentration of 5%.

6. The preparation method of a nano-capsule fire extinguishing material according to claim 3, wherein: In step S8, the washing is to wash 3 - 5 times with deionized water; the drying is vacuum freeze-drying.

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