A fluorocarbon extinguishing agent dehydration composite membrane, a preparation method and application thereof

Abstract

The application relates to the field of thin film materials, and discloses a fluorocarbon extinguishing agent dehydration composite film and a preparation method and application thereof.The dehydration composite film takes PVA as a base material, and the base material is doped with NH2-MOF-Cr@PDA.The application first synthesizes NH2-MOF-Cr, then coats an ultrathin PDA layer on the pore channel and surface of NH2-MOF-Cr by using the self-polymerization of PD, and finally dopes the NH2-MOF-Cr into PVA to prepare the composite film.The application utilizes the hydrogen bond action of PDA and PVA and the crosslinking action of a chemical crosslinking agent, can significantly improve the doping amount of NH2-MOF-Cr, and thus improves the dehydration efficiency of the composite film on fluorocarbons and does not excessively affect the mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thin film materials, in particular to a fluorocarbon extinguishing agent dehydration composite film and a preparation method and application thereof. BACKGROUND

[0002] Fluorocarbons are a class of organic compounds obtained by replacing part or all of the hydrogen in hydrocarbons with fluorine. They generally have good comprehensive heat transfer performance and can achieve non-flammability without flash point. At the same time, due to the large C-F bond energy, fluorocarbons are inert and not easy to react with other substances, making them good compatible materials. Due to their excellent physical properties, fluorocarbons can be widely used as extinguishing agents in live fire scenarios such as lithium-ion batteries, substations, and data centers.

[0003] The application characteristics of fluorocarbons determine that the water content of fluorocarbons must be very low to ensure their good insulating properties. However, the preparation of fluorocarbons involves fluorine chemical industry, and the water content of the product is usually controlled through processes such as rectification. It is difficult to control the water content of fluorocarbons to a very low level (5 ppm or less) through rectification, and the use of repeated rectification often requires a large amount of energy and large-scale process equipment.

[0004] To solve the above technical problems, the applicant tried to use polyvinyl alcohol films doped with hollow MOF particles to filter and remove water from fluorocarbons in the early stage. However, due to the physical mixing between hollow MOF particles and polyvinyl alcohol, the doping amount is limited to 3wt%, because when the particle doping amount reaches a certain level, interface gaps will appear between the particles and the polymer, and the particles will not be uniformly dispersed, which will affect the dehydration efficiency and mechanical properties of the film. SUMMARY

[0005] To solve the above technical problems, the present application provides a fluorocarbon extinguishing agent dehydration composite film and a preparation method and application thereof. The present application first synthesizes NH2-MOF-Cr, then uses the self-polymerization of PD to coat a layer of ultra-thin PDA on the pores and surface of NH2-MOF-Cr, and finally dopes it into PVA to obtain a composite film. The present application uses the hydrogen bonding between PDA and PVA and the cross-linking effect of the chemical cross-linking agent to significantly improve the doping amount of NH2-MOF-Cr, thereby improving the dehydration efficiency of the composite film for fluorocarbons without excessively affecting the mechanical properties.

[0006] The specific technical solutions of the present application are as follows:

[0007] In a first aspect, the present application provides a fluorocarbon extinguishing agent dehydration composite membrane, which is based on polyvinyl alcohol as a substrate, and the substrate is doped with NH2-MOF-Cr@PDA composite material; wherein NH2-MOF-Cr is a porous organic metal framework material containing NH2 and Cr, and the channels and surface of NH2-MOF-Cr are modified with in-situ self-polymerized polydopamine, and the polyvinyl alcohol is crosslinked with NH2-MOF-Cr@PDA composite material through hydrogen bonds and chemical bonds.

[0008] The present application first synthesizes NH2-MOF-Cr with high specific surface area and porous structure, then coats a layer of ultra-thin polydopamine (PDA) on the channels and surface of NH2-MOF-Cr through self-polymerization of dopamine, and then dopes it into polyvinyl alcohol (PVA) for compounding. NH2-MOF-Cr is an organic metal framework material with -NH2, which has the advantages of high stability in water, strong hydrophilicity, large specific surface area, and high porosity. The reason for choosing PVA as the substrate of the composite membrane is that: on the one hand, PVA is a hydrophilic polymer that can effectively separate hydrophobic substances; and on the other hand, compared with directly doping NH2-MOF-Cr into PVA, in the present application, PDA contains a large number of -NH2 and has high activity, which can form hydrogen bonds with -OH in PVA, and the crosslinking effect of glutaraldehyde and other chemical crosslinking agents can significantly improve the compatibility between NH2-MOF-Cr@PDA and PVA, so that NH2-MOF-Cr@PDA has good dispersibility in the substrate, which can greatly increase the doping amount of NH2-MOF-Cr in the composite membrane, thereby further improving the dehydration efficiency of the thin film without affecting the mechanical properties.

[0009] Preferably, the doping amount of NH2-MOF-Cr@PDA composite material in polyvinyl alcohol is 5-40wt%.

[0010] It is found that within the doping amount range of 0-40% of NH2-MOF-Cr@PDA, the dehydration performance of the composite membrane improves with the increase of the doping amount, but when it reaches 50%, the doping amount reaches the upper limit, which exceeds the bearing capacity of the composite membrane, resulting in that NH2-MOF-Cr@PDA cannot be effectively dispersed, and therefore the dehydration performance cannot be further improved. In terms of mechanical properties, within the doping amount range of 0-40%, the mechanical properties of the composite membrane decrease with the increase of the doping amount, but can still meet the practical requirements, so the influence is not great, but when it reaches 50%, the mechanical properties decrease significantly due to the doping amount exceeding the bearing capacity of the thin film, and cannot meet the use requirements.

[0011] As preferred, the thickness of the dehydration composite film is 3-6 μm.

[0012] In a second aspect, the present application provides a preparation method of a fluorocarbon fire extinguishing agent dehydration composite film, comprising the following steps:

[0013] S1: CrO3, sodium anthranilate and HCl are dissolved in water, transferred to a reactor, heated for reaction, and after centrifugal collection of the solid, washing and drying, a NH2-MOF-Cr powder with a porous structure is obtained.

[0014] S2: Dopamine is added to the basic solution, and after dissolution, the NH2-MOF-Cr powder is added, a dopamine self-polymerization reaction is carried out, and after the reaction is completed, the solid is collected by centrifugation, washed to remove the unreacted dopamine in the pores and on the surface of the NH2-MOF-Cr powder, and dried to obtain a NH2-MOF-Cr@PDA composite material.

[0015] S3: Polyvinyl alcohol is added to water, heated and stirred until a viscous polyvinyl alcohol solution is formed, and un-dissolved polyvinyl alcohol and bubbles in the solution are removed by filtration; the NH2-MOF-Cr@PDA composite material is added to the polyvinyl alcohol solution, ultrasonic stirring is carried out for dispersion, and during this process, the pH of the system is first adjusted to 1.5-2.0, and then glutaraldehyde is added to obtain a film-forming solution.

[0016] S4: The film-forming solution is uniformly coated on a smooth plane, left to stand, and dried to obtain a NH2-MOF-Cr@PDA composite film, i.e. a fluorocarbon fire extinguishing agent dehydration composite film.

[0017] As preferred, in S1: the molar ratio of CrO3, sodium anthranilate, HCl and water is 1:(0.8-1.2):(1.8-2.2):(2.5-2.9).

[0018] As preferred, in S1: the heating reaction is carried out at 150-170℃ for 6-8 days.

[0019] As preferred, in S1: the washing is carried out with deionized water and anhydrous methanol for 2-4 times respectively; and the drying is carried out at 85-95℃ under vacuum for 10-15h.

[0020] As preferred, in S2: the basic solution is Tris buffer with pH=8-9; the concentration of dopamine in the basic solution is 0.8-1.2mg / mL, and the mass ratio of dopamine to NH2-MOF-Cr powder is 1:5-10.

[0021] The ratio of dopamine and NH2-MOF-Cr powder is critical, if the amount of PDA is too much, in addition to being coated on the surface of NH2-MOF-Cr, it will also enter the inside of NH2-MOF-Cr, block the internal pore, affect the effect of NH2-MOF-Cr porosity on water removal; if the amount of PDA is too small, the PDA layer coated on the surface of NH2-MOF-Cr is not enough, resulting in that after being added to the polyethylene glycol substrate, part of the particles cannot produce chemical crosslinking, affecting the addition amount.

[0022] As preferred, in S2: the reaction time of the self-polymerization reaction is 1-10h; the washing is washing with methanol.

[0023] As preferred, in S3: the ratio of the amount of polyvinyl alcohol and water is 3-7g / 90mL; the heating and stirring temperature is 95-100℃, and the time is 10-15h; the ultrasonic stirring dispersion is stirring at room temperature for 20-30h, and ultrasonic for 15-20min every 1.5-2.5h; the mass ratio of glutaraldehyde and polyvinyl alcohol is 1:75-85.

[0024] As preferred, in S4: the standing time is 20-30h; the drying is vacuum drying at 75-85℃ for 10-15h.

[0025] In a third aspect, the application provides the application of the above-mentioned dehydrated composite film in the dehydration of fluorocarbon extinguishing agent.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] (1) The application first synthesizes NH2-MOF-Cr, then coats a layer of ultra-thin polydopamine (PDA) on the pores and surface of NH2-MOF-Cr by self-polymerization of dopamine, and then incorporates it into polyvinyl alcohol (PVA) for compounding. Among them: PVA has high hydrophilicity, and NH2-MOF-Cr is highly stable in water, has strong hydrophilicity, large specific surface area and high porosity, and can improve the dehydration effect when incorporated into PVA.

[0028] (2) Compared with the physical doping method, the application utilizes the hydrogen bond action of PDA and PVA, and the crosslinking action of glutaraldehyde and other chemical crosslinking agents, which can significantly improve the compatibility between NH2-MOF-Cr@PDA and PVA, greatly increase the doping amount of NH2-MOF-Cr in the composite film, and further improve the dehydration efficiency of the film on fluorocarbons without affecting the mechanical properties. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 SEM (left) and TEM (right) images of NH2-MOF-Cr@PDA prepared in Example 1;

[0030] Figure 2 SEM image of the top surface of the NH2-MOF-Cr@PDA-PVA composite film prepared in Example 1;

[0031] Figure 3 SEM image of the cross-section of the NH2-MOF-Cr@PDA-PVA composite film prepared in Example 1;

[0032] Figure 4 FTTR spectra of pure PVA, NH2-MOF-Cr (Example 1) and NH2-MOF-Cr@PDA-PVA (Example 1);

[0033] Figure 5 Connection schematic diagram of the dehydration rate performance testing device in the embodiment of the application.

[0034] The reference signs are: feed tank 1, peristaltic pump 2, membrane module 3, composite membrane 4, liquid nitrogen freezing container 6, vacuum gauge 7, vacuum pump 8, circulating pump 9. DETAILED DESCRIPTION

[0035] The application will be further described below in conjunction with examples.

[0036] General examples

[0037] A fluorocarbon extinguishing agent dehydration composite film with a thickness of 3-6 μm; polyvinyl alcohol is used as a base material, and 5-40 wt% of NH2-MOF-Cr@PDA composite material is doped in the base material; wherein NH2-MOF-Cr is a porous organic metal framework material containing NH2 and Cr, the pores and surface of NH2-MOF-Cr are modified with in-situ self-polymerized polydopamine, and polyvinyl alcohol is crosslinked with the NH2-MOF-Cr@PDA composite material through hydrogen bonds and chemical bonds.

[0038] A preparation method of a fluorocarbon extinguishing agent dehydration composite film, comprising the following steps:

[0039] S1: CrO3, sodium anthranilate and HCl are dissolved in water according to a molar ratio of 1:(0.8-1.2):(1.8-2.2):(2.5-2.9), transferred to a reactor, heated to 150-170℃ and reacted for 6-8 days, centrifuged to collect the solid, washed with deionized water and anhydrous methanol for 2-4 times respectively, and vacuum dried at 85-95℃ for 10-15 h to obtain NH2-MOF-Cr powder with a porous structure.

[0040] S2: Dopamine was added to the basic solution (Tris buffer with pH = 8-9) to 0.8-1.2 mg / mL, and after dissolving, NH2-MOF-Cr powder (the mass ratio of dopamine and NH2-MOF-Cr powder was 1:5-10) was added, and dopamine self-polymerization reaction was carried out for 1-10 h. After the reaction was completed, the solid was collected by centrifugation, and the NH2-MOF-Cr powder channel and the unreacted dopamine on the surface were removed by washing with methanol, and dried to obtain the NH2-MOF-Cr@PDA composite material.

[0041] S3: Polyvinyl alcohol was added to water at a ratio of 3-7 g / 90 mL, heated and stirred at 95-100 °C for 10-15 h to form a viscous polyvinyl alcohol solution, and the undissolved polyvinyl alcohol and bubbles in the solution were removed by filtration; NH2-MOF-Cr@PDA composite material was added to the polyvinyl alcohol solution, stirred at room temperature for 20-30 h, and ultrasonic was performed every 1.5-2.5 h for 15-20 min; during which the pH of the system was first adjusted to 1.5-2.0, and then glutaraldehyde (the mass ratio of glutaraldehyde and polyvinyl alcohol was 1:75-85) was added to obtain a film forming solution.

[0042] S4: The film forming solution was uniformly coated on the smooth side of the PA (polyacrylonitrile) covered with PA, and placed for 20-30 h, and vacuum dried at 75-85 °C for 10-15 h to obtain the NH2-MOF-Cr@PDA composite film, i.e. the fluorocarbon fire extinguishing agent dehydration composite film.

[0043] Example 1

[0044] S1: 12.5 mmol of CrO3, 12.5 mmol of sodium anthranilate and 25 mmol of HCl were dissolved in 50 mL of water, and transferred to a reaction kettle, heated to 160 °C and reacted for 7 days. After the solid was collected by centrifugation, it was washed with deionized water and anhydrous methanol for 3 times respectively, and vacuum dried at 90 °C for 12 h to obtain the NH2-MOF-Cr powder with a porous structure.

[0045] S2: Dopamine was added to the basic solution (Tris buffer with pH = 8-9) to 0.8-1.2 mg / mL, and after dissolving, NH2-MOF-Cr powder (the mass ratio of dopamine and NH2-MOF-Cr powder was 1:5-10) was added, and dopamine self-polymerization reaction was carried out for 1-10 h. After the reaction was completed, the solid was collected by centrifugation, and the NH2-MOF-Cr powder channel and the unreacted dopamine on the surface were removed by washing with methanol, and dried to obtain the NH2-MOF-Cr@PDA composite material.

[0046] S3: 5 g of polyvinyl alcohol was taken into 90 mL of deionized water, heated and stirred at 95 °C for 12 h to form a viscous polyvinyl alcohol solution, and then filtered to remove the undissolved polyvinyl alcohol and bubbles in the solution; NH2-MOF-Cr@PDA composite material was added to the polyvinyl alcohol solution to a content of 40 wt%, stirred at room temperature for 24 h, and ultrasonic treatment was performed every 2 h for 20 min; during this period, the pH of the system was first adjusted to 2 with sulfuric acid, and then 0.25 g of glutaraldehyde aqueous solution was added to obtain a film-forming solution.

[0047] S4: The film-forming solution was uniformly coated on the smooth side of PA (polyacrylonitrile), and then left to stand for 24 h to allow the solvent to slowly evaporate. The obtained composite film was vacuum dried at 80 °C for 12 h to obtain an NH2-MOF-Cr@PDA composite film with a thickness of about 4 microns, which was stored in a dry environment for characterization and testing.

[0048] Figure 1 SEM (left) and TEM (right) images of NH2-MOF-Cr@PDA prepared for Example 1. It can be seen from the images that the size of NH2-MOF-Cr@PDA is generally less than 500 nm, and the corresponding PDA coating layer thickness is 20-60 nm. Figure 1

[0049] Figure 2 SEM image of the top surface of the NH2-MOF-Cr@PD-PVA composite film prepared for Example 1. As can be seen from the image, for the NH2-MOF-Cr@PD-PVA composite film, even when the loading amount of NH2-MOF-Cr@PD is as high as 40 wt%, the filler particles NH2-MOF-Cr@PDA in the PVA matrix are still in a uniformly dispersed state without obvious agglomeration.

[0050] Figure 3 SEM cross-sectional image of the NH2-MOF-Cr@PD-PVA composite film prepared for Example 1. As can be seen from the SEM image of the composite film, the prepared NH2-MOF-Cr@PD-PVA composite film has a thickness of about 4 μm. The compatibility between NH2-MOF-Cr@PDA filler particles and PVA is good, thereby allowing the NH2-MOF-Cr@PDA filler particles to remain uniformly dispersed in the PVA matrix.

[0051] Figure 4 FTTR spectra of pure PVA, NH2-MOF-Cr (Example 1), and NH2-MOF-Cr@PDA (Example 1). As can be seen from the image, the stretching vibration peak (3400 cm -1 ) belonging to -OH in PVA has shifted, which is due to the hydrogen bonding between -OH and -NH2 in PDA. The peaks at 2898 to 2935 cm -1 ​The peak band between 1300 and 1500 cm-1 belongs to the asymmetric symmetric stretching vibration of -CH2 in PVA, and the peak band of -CH2 gradually weakens with the increase of filler particle loading. In addition, due to the existence of N-H in the secondary amine in PDA, a new broad peak appears near 950 cm -1 These results show that hydrogen bonds and chemical bonds are generated between NH2-MOF-Cr@PD and PVA.

[0052] Examples 2-5 and Comparative Examples 1-5

[0053] The difference between Examples 2-5 and Comparative Examples 1-5 and Example 1 is shown in the following table:

[0054] Group number NH2-MOF-Cr doping method [CAT] NH2-MOF-Cr@PDA doping amount Mass ratio of dopamine and NH2-MOF-Cr <!-- 4 -->]]> Comparative Example 1 / 0 wt% / Example 2 Chemical doping 5 wt% 1∶8 Example 3 Chemical doping 20 wt% 1∶8 Example 4 Chemical doping 30 wt% 1∶8 Example 1 Chemical doping 40 wt% 1∶8 Comparative Example 2 Chemical doping 50 wt% 1∶8 Comparative Example 3 Chemical doping 40 wt% 1∶15 Example 5 Chemical doping 40 wt% 1∶10 Example 6 Chemical doping 40 wt% 1∶5 Comparative Example 4 Chemical doping 40 wt% 1∶3 Comparative Example 5 Physical doping* 40 wt% (NH2-MOF-Cr) /

[0055] Note: *In Comparative Example 5, NH2-MOF-Cr without PDA modification is doped, and no glutaraldehyde is added during the doping process.

[0056] Performance test

[0057] The performance of the composite membranes prepared in Examples 1-5 and Comparative Examples 1-5 was tested,

[0058] (1) Dehydration performance test: The fluorocarbon dehydration performance test process is shown in Figure 5 The moisture content of fluorocarbon before dehydration is higher than 3%, and the test area of the composite membrane is 100 cm 2 . During the test, the feed liquid is stored in a 10 L feed tank 1, the feed liquid is delivered to the composite membrane 4 in the membrane module 3 by a peristaltic pump 2 for dehydration, the membrane module is maintained at a constant temperature by a circulating water bath 5 circulating by a circulating pump 9 during the dehydration process, and the dehydrated fluorocarbon liquid is delivered back to the feed tank; the removed water is pumped into a liquid nitrogen freezing container 6, the power is provided by a vacuum pump 8, and the liquid nitrogen freezing container is connected with a vacuum gauge 7 to ensure that the permeation pressure is maintained below 500 Pa.

[0059] (2) Mechanical property test: tensile strength and elastic modulus test.

[0060] The results are as follows:

[0061]

[0062] From the comparison of the above table data:

[0063] Regarding the doping amount of NH2-MOF-Cr@PDA: In Comparative Example 1, Examples 1-4, and Comparative Example 2, the doping amount of NH2-MOF-Cr@PDA is increased in turn, and it can be found that, in terms of dehydration performance, within the doping amount range of 0-40% (Comparative Example 1, Examples 1-4), the dehydration performance of the composite film is improved with the increase of the doping amount, but when it reaches 50% (Comparative Example 2), the doping amount of NH2-MOF-Cr@PDA reaches the upper limit, which exceeds the bearing capacity of the composite film, resulting in that NH2-MOF-Cr@PDA cannot be effectively dispersed, and thus the dehydration performance cannot be further improved. In terms of mechanical performance, similarly, within the doping amount range of 0-40% (Comparative Example 1, Examples 1-4), the mechanical performance of the composite film is decreased with the increase of the doping amount, but can still meet the practical requirements, and thus the influence is not great, but when it reaches 50% (Comparative Example 2), the mechanical performance is significantly decreased due to the doping amount exceeding the bearing capacity of the film, and thus cannot meet the use requirements.

[0064] Regarding the amount of dopamine: In Comparative Example 3, Example 5, Example 1, Example 6, and Comparative Example 4, the amount of dopamine is increased in turn compared with NH2-MOF-Cr, and it can be found that, in terms of dehydration performance, each group has good dehydration performance except Comparative Example 4, which is because the amount of dopamine in Comparative Example 4 is too high, resulting in that PDA not only coats the surface of NH2-MOF-Cr, but also enters the interior of NH2-MOF-Cr, thereby blocking the internal pores and affecting the effect of the porosity of NH2-MOF-Cr on water removal. In terms of mechanical performance, it can be found that the mechanical performance of the composite film is gradually improved with the increase of the amount of dopamine. Among them, the mechanical performance in Comparative Example 3 is the worst and cannot meet the use requirements. This is because the amount of dopamine is too small, and the PDA layer coated on the surface of NH2-MOF-Cr is not enough, resulting in that, after being added to the polyethylene glycol substrate, part of the particles cannot produce sufficient chemical cross-linking.

[0065] Regarding the doping method of NH2-MOF-Cr@PDA: The difference between Example 1 and Comparative Example 5 is that Comparative Example 5 dopes NH2-MOF-Cr without PDA modification, and glutaraldehyde is not added during the doping process. It can be found that, compared with the chemical doping method (chemical cross-linking) of Example 1, the upper limit of the doping amount of NH2-MOF-Cr is lower in the physical doping method, and under the same doping amount of 40%, interface gaps will appear between NH2-MOF-Cr and the polymer, and the particles will not be uniformly dispersed between the particles, which will significantly affect the dehydration efficiency and mechanical performance of the film.

[0066] The raw materials and equipment used in the present application are conventional raw materials and equipment in the art unless otherwise specified; the methods used in the present application are conventional methods in the art unless otherwise specified.

[0067] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application. Any simple modification, change, and equivalent transformation of the above embodiments according to the technical essence of the present application are still within the protection scope of the technical scheme of the present application.

Claims

1. A fluorocarbon fire extinguishant dehydration composite membrane characterized by: A polyvinyl alcohol is used as a base material, and the base material is doped with an NH2-MOF-Cr@PDA composite material; wherein the NH2-MOF-Cr is a porous organic metal framework material containing NH2 and Cr, the pores and surface of the NH2-MOF-Cr are decorated with in-situ self-polymerized polydopamine, and the polyvinyl alcohol is crosslinked with the NH2-MOF-Cr@PDA composite material through hydrogen bonds and chemical bonds.

2. The fluorocarbon fire extinguishant dewatering composite membrane of claim 1, wherein: The doping amount of the NH2-MOF-Cr@PDA composite material in the polyvinyl alcohol is 5-40 wt%.

3. The fluorocarbon extinguishing agent dewatering composite membrane according to claim 1 or 2, characterized by: The thickness is 3-6 μm.

4. A method for producing a fluorocarbon extinguishing agent dehydration composite membrane as claimed in any one of claims 1 to 3, characterized by The method comprises the following steps: S1: CrO3, sodium anthranilate and HCl are dissolved in water, transferred to a reactor, heated and reacted, the solid is collected by centrifugation, washed, dried, and NH2-MOF-Cr powder with a porous structure is obtained; S2: Dopamine is added to an alkaline solution, and after dissolution, NH2-MOF-Cr powder is added, a dopamine self-polymerization reaction is carried out, the solid is collected by centrifugation after the reaction is completed, unreacted dopamine is removed by washing, and dried to obtain an NH2-MOF-Cr@PDA composite material; S3: Polyvinyl alcohol is added to water, heated and stirred until a viscous polyvinyl alcohol solution is formed, and un-dissolved polyvinyl alcohol and bubbles in the solution are removed by filtration; NH2-MOF-Cr@PDA composite material is added to the polyvinyl alcohol solution, ultrasonic stirring and dispersion are carried out, the pH of the system is adjusted to 1.5-2.0 first, and then glutaraldehyde is added to obtain a film-forming solution; S4: The film-forming solution is uniformly coated on a smooth plane, left to stand, dried, and an NH2-MOF-Cr@PDA composite film, i.e. a fluorocarbon compound extinguishing agent dehydration composite film, is prepared.

5. The production method according to claim 4, characterized by: In S1: The molar ratio of CrO3, sodium anthranilate, HCl and water is 1:(0.8-1.2):(1.8-2.2):(2.5-2.9); The heating reaction is carried out at 150-170℃ for 6-8 days.

6. The production method according to claim 4 or 5, characterized by: In S1: The washing is washing with deionized water and anhydrous methanol for 2-4 times respectively; The drying is vacuum drying at 85-95℃ for 10-15h.

7. The production method according to claim 4, wherein: In S2: The alkaline solution is Tris buffer with pH=8-9; The concentration of dopamine in the alkaline solution is 0.8-1.2 mg / mL; The mass ratio of dopamine to NH2-MOF-Cr powder is 1:5-10; The reaction time of the self-polymerization reaction is 1-10h; The washing is washing with methanol.

8. The production method according to claim 4, characterized by: In S3: The ratio of the amount of polyvinyl alcohol to water is 3-7g / 90mL; The heating and stirring temperature is 95-100℃, and the time is 10-15h; The ultrasonic stirring and dispersion is stirring at room temperature for 20-30h, and ultrasonic treatment is carried out every 1.5-2.5h for 15-20 min; The mass ratio of glutaraldehyde to polyvinyl alcohol is 1:75-85.

9. The production method according to claim 4, wherein: In S4: The standing time is 20-30h; The drying is vacuum drying at 75-85℃ for 10-15h.

10. Use of the dehydrated composite membrane according to any one of claims 1 to 3 or the dehydrated composite membrane obtained by the method according to any one of claims 4 to 9 for the dehydration of fluorocarbon fire extinguishing agents.

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