Preparation method and application of a DOPO modified triazine-based covalent organic framework flame retardant

Abstract

The application provides a preparation method of a DOPO modified triazine-based covalent organic framework flame retardant and application thereof, and the preparation method of the flame retardant comprises the following steps: preparing a triazine-based covalent organic framework; and chemically modifying the triazine-based covalent organic framework with DOPO to obtain a DOPO modified triazine-based covalent organic framework flame retardant. The triazine-based covalent organic framework material is chemically modified on the surface by DOPO, and is used as an epoxy resin organic filler to be cured to obtain a green halogen-free environmentally-friendly flame-retardant epoxy resin. The epoxy resin does not cause environmental pollution during thermal cracking or combustion, and is conducive to environmental protection and sustainable development. The epoxy resin has excellent flame-retardant performance, greatly reduces the release of heat, smoke and harmful gases in the combustion process of the epoxy resin, and greatly enhances the fire safety of the epoxy resin.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant polymer materials technology, specifically to a method for preparing a DOPO-modified triazine-based covalent organic framework flame retardant and its application. Background Technology

[0002] Epoxy resin is one of the most common thermosetting polymers, possessing excellent chemical resistance, mechanical properties, and adhesion, and is widely used in many engineering fields and our daily lives. However, the inherent flammability of epoxy resin hinders its practical application in many areas, and the large amount of heat and toxic fumes released when epoxy resin burns are a major cause of death in humans and animals. Therefore, research into designing novel epoxy resin composite materials with excellent flame retardancy, thermal stability, and smoke-resistant properties is essential.

[0003] In recent years, phosphorus-based flame retardants have been considered highly efficient halogen-free alternatives due to their good thermal stability and low toxicity. Of particular note is the widely used 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative. During combustion, DOPO not only enhances solid-phase carbonization but also induces a free radical quenching effect due to the presence of HPO₂· and PO· in the gas phase.

[0004] Due to their periodic network structure and high porosity and specific surface area, organic framework materials such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen-bonded organic frameworks (HBOFs) have been widely used in gas adsorption / separation, catalysis, energy, and optoelectronics. Because of their good thermal stability and polymer compatibility, these organic framework materials can be used to construct excellent polymer composites and, theoretically, improve the fire safety of polymers. Covalent organic frameworks are a class of two- or three-dimensional crystalline porous nanostructures linked by covalent bonds. Due to their high specific surface area, regular pores, and high stability, covalent organic framework materials have received widespread attention and application in many fields such as catalysis, photovoltaics, gas adsorption / separation, and energy. In the field of flame retardancy, using covalent organic framework materials as flame retardants has significant advantages. The naturally highly conjugated structure of covalent organic framework materials helps to mitigate localized overheating and inhibits the spread of ignition sources in polymers by enhancing heat transfer. Due to their inherent cavities, covalent organic framework materials are also excellent adsorbents for harmful gases. Covalent organic framework materials based on triazine or containing nitrile groups are considered an important subclass of covalent organic framework materials. Generally speaking, triazine-based covalent organic frameworks exhibit superior thermal stability compared to other covalent organic frameworks. Furthermore, their flame retardancy stems from the oxygen concentration dilution effect caused by the nitrogen-rich triazine ring. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a method for preparing a DOPO-modified triazine-based covalent organic framework flame retardant and its application.

[0006] To achieve the above-mentioned objective, in a first aspect, the present invention provides a method for preparing a DOPO-modified triazine-based covalent organic framework flame retardant, comprising:

[0007] Preparation of triazine-based covalent organic frameworks;

[0008] Triazine covalent organic frameworks were chemically modified with DOPO to obtain DOPO-modified triazine covalent organic framework flame retardants.

[0009] In one embodiment, a method for preparing a triazine-based covalent organic framework includes:

[0010] Preparation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine: 4-aminobenzonitrile was dissolved in chloroform, then argon gas was introduced and the mixture was cooled to 0 degrees Celsius; subsequently, trifluoromethanesulfonic acid was added dropwise and stirred at room temperature; the mixture was diluted with distilled water and neutralized with sodium hydroxide solution; finally, the resulting mixture was filtered, and the residue was washed with distilled water to collect the product;

[0011] Preparation of triazine-based covalent organic framework: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was dissolved in N,N-dimethylacetamide, and then mixed with benzoxaldehyde in the N,N-dimethylacetamide solution; 1,2-dichlorobenzene and acetic acid were added to the mixture, and the solution was allowed to stand; the solution was then filtered and washed, and the resulting product was dried under vacuum for 24 hours.

[0012] In one embodiment, a flame retardant is obtained by chemically modifying a triazine-based covalent organic framework with DOPO, comprising:

[0013] Triazine-based covalent organic frameworks were uniformly dispersed in a tetrahydrofuran solution; then, DOPO and polyoxymethylene were added to the above mixture solution; under a nitrogen atmosphere, the mixture was vigorously stirred at a certain temperature using a reflux condenser; the final DOPO-modified triazine-based covalent organic framework flame retardant was obtained through washing and vacuum drying processes.

[0014] Secondly, the present invention provides the application of the DOPO-modified triazine-based covalent organic framework flame retardant prepared by the above-mentioned method for preparing the DOPO-modified triazine-based covalent organic framework flame retardant.

[0015] In one embodiment, it is used to prepare a flame-retardant epoxy resin.

[0016] In one embodiment, the obtained DOPO-modified triazine covalent organic framework flame retardant is dispersed in bisphenol A type epoxy resin by mechanical stirring to obtain a uniform mixture. Then, the mixture is reacted at a certain temperature for a period of time, and an aromatic diamine curing agent is added. The mixture is stirred until an epoxy resin solution is obtained. Finally, the epoxy resin solution is vacuumed to remove air bubbles, then poured into a preheated mold and thermo-cured. After curing, it is cooled to room temperature. Finally, a flame-retardant epoxy resin is prepared.

[0017] In one embodiment, the mass ratio of DOPO-modified triazine covalent organic framework flame retardant to bisphenol A type epoxy resin is 3 to 12:100.

[0018] In one embodiment, the mass ratio of aromatic diamine curing agent to bisphenol A type epoxy resin is 18-26:100.

[0019] In one embodiment, the reaction temperature of the DOPO-modified triazine covalent organic framework flame retardant and the bisphenol A type epoxy resin is 85–120°C, and the reaction time is 40–60 minutes.

[0020] The advantages and beneficial effects of this invention compared to the prior art are as follows:

[0021] (1) The flame-retardant epoxy resin containing DOPO-modified triazine covalent organic framework flame retardant is simple to process, easy to control and highly efficient.

[0022] (2) The DOPO-modified triazine covalent organic framework flame retardant provided by the present invention is a phosphorus- and nitrogen-containing compound that has a certain hydrogen bonding effect with the substrate and has good compatibility with epoxy resin.

[0023] (3) The DOPO-modified triazine covalent organic framework flame retardant provided by the present invention is used to retard epoxy resin. The DOPO-modified triazine covalent organic framework flame retardant has abundant phosphorus and nitrogen flame retardant elements, and has obvious flame retardant effect. It can act on both the gas phase and the solidified phase at the same time.

[0024] (4) This invention discloses the preparation of a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) modified triazine-based covalent organic framework composite material and its application in the field of flame-retardant epoxy resin. A green, halogen-free, environmentally friendly flame-retardant epoxy resin is prepared by surface chemical modification of the triazine-based covalent organic framework material with DOPO and then using it as an organic filler in epoxy resin through curing. It does not cause environmental pollution during thermal decomposition or combustion, which is beneficial to environmental protection and sustainable development. It has excellent flame-retardant properties, greatly reducing the release of heat, smoke, and harmful gases during the combustion process of epoxy resin, and significantly enhancing its fire safety. Attached Figure Description

[0025] Figure 1 The graph shows the heat release rate of the flame-retardant epoxy resin containing DOPO-modified triazine covalent organic framework flame retardant obtained in Example 1.

[0026] Figure 2 The graph shows the smoke release rate of the flame-retardant epoxy resin containing DOPO-modified triazine covalent organic framework flame retardant obtained in Example 2.

[0027] Figure 3 This is a graph showing the carbon monoxide formation rate of the DOPO-modified triazine covalent organic framework flame retardant epoxy resin obtained in Example 3.

[0028] Figure 4 The graph shows the carbon dioxide generation rate of the flame-retardant epoxy resin containing DOPO-modified triazine covalent organic framework flame retardant obtained in Example 4. Detailed Implementation

[0029] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0030] In a first aspect, the present invention provides a method for preparing a DOPO-modified triazine-based covalent organic framework flame retardant, comprising:

[0031] Preparation of triazine-based covalent organic frameworks;

[0032] Triazine covalent organic frameworks were chemically modified with DOPO to obtain DOPO-modified triazine covalent organic framework flame retardants.

[0033] Furthermore, the preparation method of the triazine-based covalent organic framework includes:

[0034] Preparation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine: 4-aminobenzonitrile was dissolved in chloroform, then argon gas was introduced and the mixture was cooled to 0 degrees Celsius; subsequently, trifluoromethanesulfonic acid was added dropwise and stirred at room temperature; the mixture was diluted with distilled water and neutralized with sodium hydroxide solution; finally, the resulting mixture was filtered, and the residue was washed with distilled water to collect the product;

[0035] Preparation of triazine-based covalent organic framework: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was dissolved in N,N-dimethylacetamide, and then mixed with benzoxaldehyde in the N,N-dimethylacetamide solution; 1,2-dichlorobenzene and acetic acid were added to the mixture, and the solution was allowed to stand; the solution was then filtered and washed, and the resulting product was dried under vacuum for 24 hours.

[0036] Furthermore, flame retardants were obtained by chemically modifying triazine-based covalent organic frameworks with DOPO, including:

[0037] Triazine-based covalent organic frameworks were uniformly dispersed in a tetrahydrofuran solution; then, DOPO and polyoxymethylene were added to the above mixture solution; under a nitrogen atmosphere, the mixture was vigorously stirred at a certain temperature using a reflux condenser; the final DOPO-modified triazine-based covalent organic framework flame retardant was obtained through washing and vacuum drying processes.

[0038] Secondly, the present invention provides the application of the DOPO-modified triazine-based covalent organic framework flame retardant prepared by the above-mentioned method for preparing the DOPO-modified triazine-based covalent organic framework flame retardant.

[0039] Furthermore, it is used to prepare flame-retardant epoxy resins.

[0040] Furthermore, the obtained DOPO-modified triazine covalent organic framework flame retardant was dispersed in bisphenol A type epoxy resin by mechanical stirring to obtain a homogeneous mixture. Then, the mixture was reacted at a certain temperature for a period of time, and an aromatic diamine curing agent was added. The mixture was stirred until an epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuumed to remove air bubbles, then poured into a preheated mold and thermo-cured. After curing, it was cooled to room temperature. Finally, a flame-retardant epoxy resin was prepared.

[0041] Furthermore, the mass ratio of DOPO-modified triazine-based covalent organic framework flame retardant to bisphenol A type epoxy resin is 3–12:100, for example, 3:100, 4:100, 6:100, 8:100, 10:100, 12:100, etc. Within this range, the mass ratio of DOPO-modified triazine-based covalent organic framework flame retardant to bisphenol A type epoxy resin can not only effectively improve the flame retardant properties of epoxy resin composites, but also avoid the reduction in mechanical properties of epoxy resin composites due to excessive flame retardant dosage.

[0042] Furthermore, the mass ratio of aromatic diamine curing agent to bisphenol A type epoxy resin is 18–26:100, for example, 18:100, 20:100, 21:100, 23:100, 24:100, 26:100, etc. Within this range, the mass ratio of aromatic diamine curing agent to bisphenol A type epoxy resin can effectively cure the epoxy resin and avoid problems such as insufficient curing and curing agent involvement that could affect the mechanical properties of the epoxy resin.

[0043] Furthermore, the reaction temperature of the DOPO-modified triazine covalent organic framework flame retardant and bisphenol A type epoxy resin is 85–120°C, for example, 80°C, 100°C, 110°C, 120°C, etc.; the reaction time is 40–60 minutes, for example, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, etc.; the optimal reaction conditions are selected according to the ratio of triazine covalent organic framework flame retardant and bisphenol A type epoxy resin, and the reaction temperature and reaction time are reasonably controlled to obtain a hot epoxy resin solution that is uniformly mixed with the flame retardant.

[0044] According to experiments, the optimal conditions are a mass ratio of DOPO-modified triazine covalent organic framework flame retardant, bisphenol A type epoxy resin, and aromatic diamine curing agent of 3:77:20. When these components are uniformly mixed at 100°C for 40 minutes, the epoxy resin composite material with the highest flame retardant efficiency and the best mechanical properties can be obtained.

[0045] This invention has undergone numerous experiments, and some of the experimental results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0046] The preparation of DOPO-modified triazine-based covalent organic framework flame retardants includes the following steps:

[0047] Preparation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine: 4-aminobenzonitrile was dissolved in chloroform, then argon gas was introduced and the mixture was cooled to 0 degrees Celsius; subsequently, trifluoromethanesulfonic acid was added dropwise and stirred at room temperature; the mixture was diluted with distilled water and neutralized with sodium hydroxide solution; finally, the resulting mixture was filtered, and the residue was washed with distilled water to collect the product.

[0048] Preparation of the triazine-based covalent organic framework: 3.57 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was dissolved in 10 mL of N,N-dimethylacetamide, and then mixed with 2.01 g of phthalaldehyde in 10 mL of N,N-dimethylacetamide solution. 50 mL of 1,2-dichlorobenzene and 10 mL of acetic acid were added to this mixture, and the solution was allowed to stand for 1 hour. The solution was then filtered and washed with N,N-dimethylformamide, and then dried under vacuum at 80°C for 24 hours.

[0049] DOPO-modified triazine-based covalent organic framework flame retardant: 2 g of triazine-based covalent organic framework material was uniformly dispersed in 200 mL of tetrahydrofuran and stirred using a magnetic stirrer. Subsequently, 1 g of DOPO and 0.2 g of polyoxymethylene were added to the mixture. Under a nitrogen atmosphere, the mixture was vigorously stirred at 50°C for 10 hours using a reflux condenser. The final DOPO-modified triazine-based covalent organic framework flame retardant was obtained through washing and vacuum drying.

[0050] Example 1

[0051] Three parts of the DOPO-modified triazine-based covalent organic framework flame retardant prepared in Example 1 were mechanically dispersed in 77 parts of bisphenol A type epoxy resin. The mixture was then heated to 100°C and reacted for 60 minutes. Subsequently, 20 parts of diaminodiphenylmethane curing agent were added, and the mixture was stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0052] The prepared flame-retardant epoxy resin specimens were subjected to cone calorimetry testing. The cone calorimetry specimens were 100mm × 100mm × 3mm in size. The heat release rate graph of the flame-retardant epoxy resin obtained in Example 1 is shown below. Figure 1 As shown in the figure. The results indicate that the addition of DOPO-modified triazine-based covalent organic framework flame retardant effectively reduced the heat release rate of the epoxy resin composite. Compared to the epoxy resin without flame retardant, the peak heat release rate of the epoxy resin composite decreased from 979.9 kW / m². 2 It dropped to 597.5 kW / m 2The decline rate was 39.0%.

[0053] Example 2

[0054] Six parts of the DOPO-modified triazine-based covalent organic framework flame retardant prepared in Example 1 were mechanically dispersed in 74 parts of bisphenol A type epoxy resin. The mixture was then heated to 100°C and reacted for 60 minutes. Subsequently, 20 parts of diaminodiphenylmethane curing agent were added, and the mixture was stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0055] The prepared flame-retardant epoxy resin specimens were subjected to cone calorimetry testing. The cone calorimetry specimens were 100mm × 100mm × 3mm in size. The smoke release rate graph of the flame-retardant epoxy resin obtained in Example 2 is shown below. Figure 2 As shown in the figure. The results indicate that the addition of DOPO-modified triazine-based covalent organic framework flame retardant effectively reduced the smoke emission rate of the epoxy resin composite. Compared to the epoxy resin without flame retardant, the peak smoke emission rate of the epoxy resin composite decreased from 0.291 m³ / s. 2 / s decreased to 0.230m 2 / s, a decrease of 21.0%.

[0056] Example 3

[0057] Nine parts of the DOPO-modified triazine-based covalent organic framework flame retardant prepared in Example 1 were mechanically dispersed in 71 parts of bisphenol A type epoxy resin. The mixture was then heated to 100°C and reacted for 60 minutes. Subsequently, 20 parts of diaminodiphenylmethane curing agent were added, and the mixture was stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0058] The prepared flame-retardant epoxy resin specimens were subjected to cone calorimetry testing. The cone calorimetry specimens were 100mm × 100mm × 3mm in size. The carbon monoxide formation rate graph of the flame-retardant epoxy resin obtained in Example 3 is shown below. Figure 3 As shown in the figure. The results indicate that the addition of DOPO-modified triazine-based covalent organic framework flame retardant effectively reduced the carbon monoxide formation rate of epoxy resin composites. Compared with epoxy resin without flame retardant, the peak carbon monoxide formation rate of epoxy resin composites decreased from 0.034 g / s to 0.027 g / s, a decrease of 20.6%.

[0059] Example 4

[0060] Twelve parts of the DOPO-modified triazine-based covalent organic framework flame retardant prepared in Example 1 were mechanically dispersed in 68 parts of bisphenol A type epoxy resin. The mixture was then heated to 100°C and reacted for 60 minutes. Subsequently, 20 parts of diaminodiphenylmethane curing agent were added, and the mixture was stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0061] The prepared flame-retardant epoxy resin specimens were subjected to cone calorimetry testing. The cone calorimetry specimens were 100mm × 100mm × 3mm in size. The carbon dioxide generation rate graph of the flame-retardant epoxy resin obtained in Example 4 is shown below. Figure 4 As shown in the figure. The results indicate that the addition of DOPO-modified triazine-based covalent organic framework flame retardant effectively reduced the carbon dioxide generation rate of the epoxy resin composite. Compared with the epoxy resin without flame retardant, the peak carbon dioxide generation rate of the epoxy resin composite decreased from 0.65 g / s to 0.37 g / s, a reduction of 38.7%.

[0062] Compare with Example 1

[0063] 80 parts of bisphenol A type epoxy resin and 20 parts of diaminodiphenylmethane curing agent were mechanically mixed at 100°C to obtain an epoxy resin solution. The epoxy resin solution was then vacuum-sealed to remove air bubbles, poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the reference epoxy resin.

[0064] The prepared epoxy resin specimens were subjected to cone calorimetry testing. The cone calorimetry specimens were 100mm × 100mm × 3mm in size.

[0065] As can be seen from the above embodiments, the flame-retardant properties of the flame-retardant epoxy resins prepared by this invention are significantly improved. With the introduction of DOPO-modified triazine-based covalent organic framework flame retardants into the epoxy resins, the heat release rate, smoke release rate, carbon monoxide generation rate, and carbon dioxide generation rate during the epoxy resin combustion process are effectively reduced. This indicates that DOPO-modified triazine-based covalent organic framework flame retardants can effectively inhibit the generation of heat, smoke, and harmful gases during the epoxy resin combustion process. This suggests that DOPO-modified triazine-based covalent organic framework materials hold promise as excellent candidate materials for epoxy resin flame retardants.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of DOPO-modified triazine-based covalent organic framework flame retardant, characterized by, include: The preparation of triazine-based covalent organic frameworks specifically includes: Preparation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine: 4-aminobenzonitrile was dissolved in chloroform, then argon gas was introduced and the mixture was cooled to 0 degrees Celsius; subsequently, trifluoromethanesulfonic acid was added dropwise and stirred at room temperature; the mixture was diluted with distilled water and neutralized with sodium hydroxide solution; finally, the resulting mixture was filtered, and the residue was washed with distilled water to collect the product; Preparation of triazine-based covalent organic framework: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was dissolved in N,N-dimethylacetamide, and then mixed with phthalaldehyde in the N,N-dimethylacetamide solution; 1,2-dichlorobenzene and acetic acid were added to this mixture, and the solution was allowed to stand for 1 hour; subsequently, the solution was filtered and washed, and the resulting product was dried under vacuum for 24 hours; Triazine-based covalent organic frameworks were chemically modified with DOPO to obtain DOPO-modified triazine-based covalent organic framework flame retardants; specifically including: A triazine-based covalent organic framework was uniformly dispersed in a tetrahydrofuran solution to form a mixture solution; then, DOPO and polyoxymethylene were added to the mixture solution; under a nitrogen atmosphere, the mixture was vigorously stirred at a certain temperature using a reflux condenser; and the final DOPO-modified triazine-based covalent organic framework flame retardant was obtained through washing and vacuum drying processes.

2. The application of the DOPO-modified triazine-based covalent organic framework flame retardant prepared by the method described in claim 1.

3. Use according to claim 2, characterized in that, Used to prepare flame-retardant epoxy resins.

4. Use according to claim 3, characterized in that, The obtained DOPO-modified triazine-based covalent organic framework flame retardant was dispersed in bisphenol A type epoxy resin by mechanical stirring to obtain a homogeneous mixture. Then, the mixture was reacted at a certain temperature for a period of time, and an aromatic diamine curing agent was added. The mixture was stirred until an epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuumed to remove air bubbles, poured into a preheated mold, and thermocured. After curing, it was cooled to room temperature. The flame-retardant epoxy resin was finally prepared.

5. Use according to claim 4, characterized in that, The mass ratio of DOPO-modified triazine covalent organic framework flame retardant to bisphenol A type epoxy resin is 3–12:

100.

6. Use according to claim 4, characterized in that, The mass ratio of aromatic diamine curing agent to bisphenol A type epoxy resin is 18-26:

100.

7. Use according to claim 4, characterized in that, The reaction temperature of DOPO-modified triazine covalent organic framework flame retardant and bisphenol A type epoxy resin is 85-120℃, and the reaction time is 40-60 minutes.

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