A nitrogen-phosphorus flame retardant compound, a high flash point fire-retardant coating and their preparation methods

Abstract

This invention discloses a nitrogen-phosphorus flame-retardant compound, a high flash point fire-retardant coating, and their preparation methods, belonging to the technical field of fire-retardant coatings. The high flash point fire-retardant coating comprises the following components in parts by weight: 45-60 parts epoxy resin, 15-25 parts nitrogen-phosphorus flame-retardant compound, 5-15 parts flame-retardant additive, 20-30 parts curing agent, 2-8 parts additive, and 5-12 parts dispersant. The nitrogen-phosphorus flame-retardant compound is prepared by adding hypophosphoric acid to a nitrogen-chlorine diphenyl ring compound obtained from 2-chloro-5-hydroxybenzaldehyde and ethylenediamine as raw materials. The fire-retardant coating prepared by adding this nitrogen-phosphorus flame-retardant compound exhibits high flame-retardant performance and a high flash point.

Description

Technical Field

[0001] This invention belongs to the field of fire-retardant coating technology, and more specifically, relates to a nitrogen-phosphorus flame-retardant compound, a high flash point fire-retardant coating, and their preparation methods. Background Technology

[0002] Fire-retardant coatings are special coatings applied to the surface of combustible substrates to reduce the flammability of the coated material, inhibit the rapid spread of fire, and improve the fire resistance limit of the coated material. The fire-retardant and heat-insulating principle of ultra-thin or thin fire-retardant coatings applied to the protected structure is that the coating layer expands and foams when exposed to fire, forming foam. This foam layer not only isolates oxygen but also has good heat-insulating properties due to its porous texture, slowing down the transfer of heat to the protected substrate. According to physicochemical principles, the foam layer formed during the expansion of the coating exhibits an endothermic reaction due to volume expansion, consuming the heat generated during combustion and helping to lower the system temperature. These factors contribute to the significant fire-retardant and heat-insulating effect of the fire-retardant coating. Phosphorus-containing monomers are widely used to improve the flame retardancy of epoxy resins. However, in these systems, phosphorus compounds usually produce acidic substances, leading to early polymer degradation and the formation of large amounts of ash. Furthermore, phosphorus-containing monomers have low flame-retardant efficiency, requiring the addition of large amounts of phosphorus-containing flame retardants, which results in poor mechanical properties of the fire-retardant coating. Therefore, it is urgent to improve the flame retardant efficiency of flame retardant additives so that they can improve the fire resistance of fire-retardant coatings while ensuring the mechanical properties of the coatings.

[0003] According to the search, patent CN111647200A discloses a flame retardant containing an acetal structure, its preparation method and application. The flame retardant containing an acetal structure contains nitrogen and phosphorus elements, but does not contain two or more benzene rings. Its disadvantage is that its flame retardant effect mainly relies on nitrogen and phosphorus, and its flame retardant efficiency is low.

[0004] Furthermore, patent publication number CN111662332A, published on September 15, 2020, discloses an organophosphorus flame retardant with an active amino group. This invention also provides a method for preparing the aforementioned flame retardant, comprising the following steps: S1. reacting phenylphosphonic dichloride with a hydroxyformaldehyde compound to obtain a reaction intermediate; S2. reacting the reaction intermediate, the phosphoric acid compound, and the amino compound to obtain the organophosphorus flame retardant. This invention also provides the application of the flame retardant in the preparation of resin composite materials. This invention utilizes phosphate groups to exert the main flame-retardant effect, provides an efficient and rapidly reacting carbon source through the adjacent benzene ring structure, and improves mechanical properties while addressing the interfacial issues of the flame retardant through the active amino group, thereby achieving a synergistic effect of phosphate groups to exert a highly efficient flame-retardant effect and improve the mechanical properties of epoxy resin materials. However, the preparation method of this organophosphorus flame retardant is complex, and the degree of polymerization is difficult to control, leading to polymer instability and non-uniform size, affecting its dispersibility in the components. In addition, this organophosphorus flame retardant has a single flame-retardant component and low flame-retardant efficiency. Summary of the Invention

[0005] 1. The problem to be solved To address the problem that existing phosphorus-containing flame retardants are prone to decomposition, leading to a decrease in flame retardant performance, the present invention aims to provide a nitrogen-phosphorus flame retardant compound with high flame retardant efficiency.

[0006] Another object of the present invention is to provide a high flash point fire retardant coating containing the nitrogen-phosphorus flame retardant compound, wherein the fire retardant coating has high flame retardant properties and a high flash point.

[0007] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: This invention discloses a nitrogen-phosphorus flame retardant compound, the structural formula of which is as follows: Figure 1 As shown,

[0008] The preparation method of the nitrogen-phosphorus flame retardant compound specifically includes the following steps: Step S1, initial mixing: The solution containing ethylenediamine is added dropwise to the solution containing 2-chloro-5-hydroxybenzaldehyde to obtain mixed solution A; wherein, the mass ratio of 2-chloro-5-hydroxybenzaldehyde to ethylenediamine is (25~35):(5~8), the preferred concentration of the solution containing 2-chloro-5-hydroxybenzaldehyde is (25~35) g / (100~150) mL, and the preferred concentration of the solution containing ethylenediamine is (5~8) g / (50~60) mL; the solvent is methanol, and in addition to methanol, toluene or ethanol can also be used, as long as it can dissolve the organic matter.

[0009] Step S2, First Reaction: The mixed solution A obtained in Step S1 is heated and reacted for a period of time, then allowed to stand and cool before filtration, washing, and drying to obtain a nitrogen-chlorine diphenyl ring compound; wherein the reaction temperature is 50~60℃, the reaction time is 3~5h, the standing time is 12~24h; the drying temperature is 70~80℃, and the drying time is 24~36h, and the reaction formula is as follows. Figure 2 As shown.

[0010] Step S3, Secondary mixing: Prepare a solution containing a nitrogen-chlorine diphenyl ring compound, and add a solution containing hypophosphoric acid dropwise to the solution containing the nitrogen-chlorine diphenyl ring compound to obtain a mixed solution B; wherein, the mass ratio of the nitrogen-chlorine diphenyl ring compound to hypophosphoric acid is 1:1, and the preferred concentration of the nitrogen-chlorine diphenyl ring compound solution is (5~8) g / (100~120) mL.

[0011] Step S4, Secondary Reaction: After reacting the mixed solution B obtained in step S3 under oxygen-free conditions for a period of time, filter, wash, and dry to obtain nitrogen-phosphorus flame retardant compounds. The reaction time is 12-24 hours, and the reaction is carried out under oxygen-free conditions to prevent hydroxyl groups from being oxidized to aldehyde groups and to improve the yield of nitrogen-phosphorus flame retardant compounds. The drying temperature is 60-70℃, and the drying time is 24-32 hours. The above-mentioned nitrogen and phosphorus flame retardant compounds are added to the high flash point fire retardant coating to obtain a high flash point fire retardant coating comprising the following components in parts by weight: 45-60 parts epoxy resin, 15-25 parts nitrogen and phosphorus flame retardant compounds, 5-15 parts flame retardant additives, 20-30 parts curing agent, 2-8 parts additives, and 5-12 parts dispersant.

[0012] An organic phase can be added as a dispersant. The organic phase can be dipropylene glycol methyl ether (flash point 75°C), N-methylpyrrolidone (flash point 86.1°C), or propylene glycol (flash point 107°C). Water can also be added as a dispersant. When water is used as a dispersant, the high flash point fire retardant coating includes the following components in parts by weight: 45-60 parts of waterborne epoxy resin, 15-25 parts of nitrogen and phosphorus flame retardant compound, 5-15 parts of flame retardant additive, 20-30 parts of curing agent, 2-8 parts of additive, and 5-12 parts of water.

[0013] Preferably, the flame retardant is a mixture of alumina, cobalt dioxide, and pentaerythritol in a mass ratio of 1:1:20.

[0014] Preferably, the curing agent is a mixture of ethylenediamine and diethylenetriamine in a mass ratio of 1:1.

[0015] Preferably, the additives are formulated according to the actual application. For example, if the color needs to be changed, pigments and fillers are selected as needed, such as phthalocyanine blue, benzidine yellow, toluidine red, etc. Leveling agents, drying agents, etc. can also be added as needed.

[0016] This invention also discloses a method for preparing the above-mentioned high flash point fire-retardant coating, which specifically includes the following steps: a. A pre-formed coating is obtained by mixing epoxy resin, nitrogen-phosphorus flame retardant compound, flame retardant additive, auxiliaries and dispersant; b. Mix the pre-made coating with a curing agent to obtain a high flash point fire-retardant coating.

[0017] Phosphorus-containing monomers are widely used to improve the flame retardancy of epoxy resins. However, in these systems, phosphorus compounds typically produce acidic substances, leading to early polymer degradation and the production of phosphoric acid and metaphosphoric acid. Phosphoric acid causes the polymer to carbonize and decompose, resulting in the formation of a large amount of ash. Increased ash content reduces the density of the char layer, lowering both flame retardant performance and the protective effect on the matrix. Furthermore, phosphorus-containing monomers have low flame retardant efficiency. When using phosphorus-containing monomers as the main flame retardant, excessive addition can lead to poor mechanical properties of the fire-retardant coating. Therefore, this invention first uses 2-chloro-5-hydroxybenzaldehyde and ethylenediamine as raw materials to prepare a nitrogen-chlorine bisphenyl ring compound. Further, hypophosphoric acid is added to prepare a nitrogen-phosphorus flame-retardant compound. The thermal decomposition temperature of the prepared nitrogen-phosphorus flame-retardant compound is 350°C. This nitrogen-phosphorus flame-retardant compound, on the one hand, introduces the highly efficient flame-retardant element Cl, which can terminate the chain reaction of combustion during combustion, achieving synergistic flame retardancy between Cl and other components in the fire-retardant coating. On the other hand, it fixes hypophosphite with a diphenyl ring compound, introducing carbon elements, increasing the thickness and density of the char layer, thereby improving the flame-retardant and mechanical properties of the fire-retardant coating. Compared with the prior art (CN111662332A), the nitrogen-phosphorus flame-retardant compound of this invention has a high carbon content, the preparation process is easy to control, the product size is uniform, and the introduction of the highly efficient flame-retardant element Cl further improves its flame-retardant performance.

[0018] Furthermore, the molecular formula of nitrogen-phosphorus flame retardant compounds simultaneously incorporates P, N, and Cl elements, ensuring uniform distribution of these elements within the flame retardant. By controlling the proportions of P, N, and Cl in the nitrogen-phosphorus flame retardant compounds, during use, P in the nitrogen-phosphorus flame retardant compounds increases the char formation rate, N increases the char layer thickness, and Cl plays a role in capturing free radicals and blocking the combustion chain in the expanded char layer, achieving a synergistic effect of gas-phase flame retardancy and condensed-phase flame retardancy.

[0019] According to the national standard GB / T13690-92 "Classification and Marking of Commonly Used Hazardous Chemicals", liquids with a flash point below 60℃ are classified as hazardous materials, posing safety hazards during transportation and storage, thus limiting the application of paint thinners as a marketable commodity. Therefore, this invention refers to a flash point (closed cup) >60℃ as a high flash point. The epoxy resin used in this invention is epoxy resin 828 (molecular formula C...). 54 H 60O9 (flash point 78ºC) or epoxy resin 815 (molecular formula C) 25 H 35 ClO5, flash point 192.4ºC), epoxy resin (C 14 H 20 In addition to O4 (flash point 118.3℃), other types of epoxy resins with flash points higher than 60℃ can also be used in the fire-retardant coatings of this invention. The amount of ethylenediamine added is small and has almost no effect on the flash point of the fire-retardant coating; as well as diethylenetriamine (flash point 94℃) and pentaerythritol (flash point 200.1℃), the fire-retardant coatings prepared all have flash points above 60℃, which are high flash point fire-retardant coatings.

[0020] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The nitrogen-phosphorus flame retardant compound prepared by the present invention introduces the highly efficient flame retardant element Cl to achieve synergistic flame retardancy between Cl and other components in the fireproof coating. On the other hand, by fixing hypophosphoric acid with a diphenyl ring compound, carbon element is introduced to increase the thickness of the char layer and increase the density of the char layer, thereby improving the flame retardant performance and mechanical properties of the fireproof coating. (2) The fire-retardant coating prepared by the present invention has good flame retardant properties and a high flash point. Attached Figure Description

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0022] Figure 1 The structural formula of the nitrogen-phosphorus flame retardant compound of the present invention is shown below; Figure 2 The reaction formula for the preparation of the nitrogen-chlorine diphenyl ring compound of the present invention is as follows; Figure 3 The infrared spectrum of the nitrogen-phosphorus flame retardant compound of the present invention is shown below. Figure 4 This is a product image of the high flash point fire-retardant coating of the present invention. Detailed Implementation

[0023] The following detailed description of exemplary embodiments of the invention is taken with reference to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which the invention may be practiced. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from the spirit and scope thereof. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and not restrictive of the description of the features and characteristics of the invention, to suggest the best mode for carrying out the invention, and is sufficient to enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0024] Example 1 A high flash point fire retardant coating comprises the following components in parts by weight: 45 parts epoxy resin, 15 parts nitrogen-phosphorus flame retardant compound, 5 parts flame retardant additive, 20 parts curing agent, 2 parts additive, and 5 parts dipropylene glycol methyl ether.

[0025] The preparation method of the nitrogen-phosphorus flame retardant compound includes the following steps: Step S1, initial preparation: Add 25g of 2-chloro-5-hydroxybenzaldehyde and 100mL of methanol to a flask, mix and stir at 60℃ for 30min, and add 50mL of methanol solution containing 5g of ethylenediamine dropwise to the above solution to obtain mixed solution A; Step S2, First reaction: The mixed solution A obtained in step S1 was stirred at 50°C for 3 hours, left at room temperature for 12 hours, filtered and washed, and dried at 70°C for 24 hours to obtain the nitrogen-chlorine diphenyl ring compound. Step S3, Secondary mixing: Dissolve 5g of the nitrogen-chlorine diphenyl ring compound in 100mL of methanol, and add 30mL of methanol solution containing 5g of hypophosphoric acid to obtain mixed solution B; Step S4, Secondary Reaction: The mixed solution B obtained in step S3 was reacted in an oxygen-free environment for 12 hours. The reaction product was filtered, washed, and then dried at 60°C for 24 hours to obtain the nitrogen-phosphorus flame retardant compound. The infrared spectrum of the obtained nitrogen-phosphorus flame retardant compound is shown below. Figure 3 As shown. Among them, 3247 cm 1 The peak for NH stretching vibration is 2387 cm⁻¹. 1 The peak is the pH stretching vibration peak, at 1280 cm⁻¹. 1 This is the peak of the P=O stretching vibration, at 1045 cm⁻¹. 1 The peak for PO stretching vibration is 977 cm⁻¹. 1This is the peak of the P-OH stretching vibration, at 738 cm⁻¹. 1 The peak represents the C-Cl stretching vibration.

[0026] The flame retardant is a mixture of alumina, cobalt dioxide, and pentaerythritol in a mass ratio of 1:1:20.

[0027] The curing agent is a mixture of ethylenediamine and diethylenetriamine in a mass ratio of 1:1.

[0028] The auxiliary agent is phthalocyanine blue.

[0029] The preparation method of the high flash point fire retardant coating includes the following steps: a. A pre-formed coating is obtained by mixing epoxy resin, nitrogen-phosphorus flame retardant compound, flame retardant additive, auxiliaries, and dispersant; b. Mix the pre-made coating and the curing agent to obtain a high flash point fireproof coating.

[0030] Product images of used high flash point fire retardant coatings are shown below. Figure 4 As shown.

[0031] Example 2 A high flash point fire-retardant coating comprises the following components in parts by weight: 50 parts epoxy resin, 20 parts nitrogen-phosphorus flame retardant compound, 10 parts flame retardant additive, 25 parts curing agent, 6 parts additive, and 10 parts dipropylene glycol methyl ether.

[0032] The preparation method of the nitrogen-phosphorus flame retardant compound includes the following steps: Step S1, initial mixing: Add 30g of 2-chloro-5-hydroxybenzaldehyde and 120mL of methanol to a flask, mix and stir at 65℃ for 35min, and add 55mL of methanol solution containing 7g of ethylenediamine dropwise to the above solution to obtain mixed solution A; Step S2, First reaction: The mixed solution A obtained in step S1 was stirred at 55°C for 4 hours, left at room temperature for 18 hours, filtered and washed, and dried at 75°C for 30 hours to obtain the nitrogen-chlorine diphenyl ring compound. Step S3, Secondary mixing: Dissolve 6g of the nitrogen-chlorine diphenyl ring compound in 110mL of methanol, and add 40mL of methanol solution containing 6g of hypophosphoric acid to obtain mixed solution B; Step S4, Secondary Reaction: The mixed solution B obtained in step S3 was reacted in an oxygen-free environment for 18 hours. The reaction product was filtered, washed, and then dried at 65°C for 26 hours to obtain the nitrogen-phosphorus flame retardant compound.

[0033] The flame retardant is a mixture of alumina, cobalt dioxide, and pentaerythritol in a mass ratio of 1:1:20.

[0034] The curing agent is a mixture of ethylenediamine and diethylenetriamine in a mass ratio of 1:1.

[0035] The auxiliary agent is benzidine yellow.

[0036] The preparation method of the high flash point fire retardant coating includes the following steps: a. A pre-formed coating is obtained by mixing epoxy resin, nitrogen-phosphorus flame retardant compound, flame retardant additive, auxiliaries, and dispersant; b. Mix the pre-made coating and the curing agent to obtain a high flash point fireproof coating.

[0037] Example 3 A high flash point fire-retardant coating comprises the following components in parts by weight: 60 parts waterborne epoxy resin, 25 parts nitrogen-phosphorus flame retardant compound, 15 parts flame retardant additive, 30 parts curing agent, 8 parts additive, and 12 parts water.

[0038] The preparation method of the nitrogen-phosphorus flame retardant compound includes the following steps: Step S1, initial preparation: Add 35g of 2-chloro-5-hydroxybenzaldehyde and 150mL of methanol to a flask, mix and stir at 70℃ for 40min, and add 60mL of solution containing 8g of ethylenediamine dropwise to the above solution to obtain mixed solution A; Step S2, First reaction: The mixed solution A obtained in step S1 was stirred at 60°C for 5 hours, left at room temperature for 24 hours, filtered and washed, and dried at 80°C for 36 hours to obtain the nitrogen-chlorine diphenyl ring compound. Step S3, Secondary mixing: Dissolve 8g of the nitrogen-chlorine diphenyl ring compound in 120mL of methanol, and add 50mL of methanol solution containing 8g of hypophosphoric acid to obtain mixed solution B; Step S4, Secondary reaction: The mixed solution B obtained in step S3 was reacted in an oxygen-free environment for 24 hours. The reaction product was filtered, washed, and then dried at 70°C for 32 hours to obtain the nitrogen-phosphorus flame retardant compound.

[0039] The flame retardant is a mixture of alumina, cobalt dioxide, and pentaerythritol in a mass ratio of 1:1:20.

[0040] The curing agent is a mixture of ethylenediamine and diethylenetriamine in a mass ratio of 1:1.

[0041] The auxiliary agent is toluidine red.

[0042] The preparation method of the high flash point fire retardant coating includes the following steps: a. A pre-formed coating is obtained by mixing epoxy resin, nitrogen-phosphorus flame retardant compound, flame retardant additive, auxiliaries, and dispersant; b. Mix the pre-made coating and the curing agent to obtain a high flash point fireproof coating.

[0043] Comparative Example A fire-retardant coating comprises the following components in parts by weight: 60 parts epoxy resin, 20 parts flame retardant additive, 30 parts curing agent, 8 parts additive, and 12 parts dispersant.

[0044] The flame retardant is a mixture of alumina, cobalt dioxide, and pentaerythritol in a mass ratio of 1:1:20.

[0045] The curing agent is ethylenediamine.

[0046] The auxiliary agent is phthalocyanine blue.

[0047] The method for preparing the fire-retardant coating includes the following steps: a. Mix epoxy resin, flame retardant, additives, and dispersant to obtain a pre-coated coating; b. Mix the pre-made coating and the curing agent to obtain a fire-retardant coating.

[0048] The parameters of fire-retardant coatings prepared in Examples 1-3 were compared with the requirements of national and industry standards for various parameters. Specifically, the maximum heat release rate was measured using ASTM D7309-2007a; the proportion of decomposition residue and peak degradation temperature were measured using GB / T27761-2011; and the flash point was determined using the Binsky-Martin closed-cup method according to GB / T 261-2008. The test results are shown in Table 1. Table 1. Test results of various parameters of the fire-retardant coatings in comparative examples and experimental examples 1-3.

[0049] As shown in Table 1, the residual mass at 750℃ and peak degradation temperature of the coatings prepared in Examples 1-3 are all greater than those of the comparative example, while the maximum heat release rate is less than that of the comparative example. This indicates that the fire-retardant coatings prepared in this invention have superior flame-retardant properties. The peak degradation temperature reflects its thermal stability (flame retardancy), which is the temperature at which the thermal decomposition rate is maximum. A higher temperature indicates higher thermal stability and superior flame-retardant performance. The flash points of the fire-retardant coatings in Examples 1-3 are all >60℃, meeting the requirements for non-hazardous chemical identification in the "Regulations on the Safety Management of Hazardous Chemicals," and are therefore non-hazardous chemicals, which is beneficial for the storage and transportation of fire-retardant coatings. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nitrogen-phosphorus flame retardant compound, characterized in that, Its structural formula is .

2. A method for preparing the nitrogen-phosphorus flame retardant compound of claim 1, characterized in that, Includes the following steps: Step S1, initial mixing: Add the solution containing ethylenediamine dropwise to the solution containing 2-chloro-5-hydroxybenzaldehyde to obtain mixed solution A; Step S2, First reaction: After heating the mixed solution A obtained in step S1 for a period of time, let it stand and cool, then filter, wash and dry to obtain the nitrogen-chlorine diphenyl ring compound; Step S3, Secondary mixing: Prepare a solution containing a nitrogen-chlorine diphenyl ring compound. Add the solution containing hypophosphoric acid dropwise to the solution containing the nitrogen-chlorine diphenyl ring compound to obtain mixed solution B; Step S4, Secondary reaction: After reacting the mixed solution B obtained in step S3 in an oxygen-free environment for a period of time, filter, wash, and dry to obtain a nitrogen-phosphorus flame retardant compound.

3. The method for preparing a nitrogen-phosphorus flame retardant compound according to claim 2, characterized in that, The mass ratio of 2-chloro-5-hydroxybenzaldehyde to ethylenediamine is (25~35):(5~8), and the mass ratio of the nitrogen-chlorine bisphenyl ring compound to hypophosphoric acid is 1:

1.

4. The method for preparing a nitrogen-phosphorus flame retardant compound according to claim 3, characterized in that, In step S2, the reaction temperature is 50~60℃, the reaction time is 3~5h, the standing time is 12~24h, the drying temperature is 70~80℃, and the drying time is 24~36h; in step S4, the reaction time is 12~24h, the drying temperature is 60~70℃, and the drying time is 24~32h.

5. A high flash point fire-retardant coating, characterized in that, The composition comprises the following components in parts by weight: 45-60 parts epoxy resin, 15-25 parts nitrogen-phosphorus flame retardant compound, 5-15 parts flame retardant additive, 20-30 parts curing agent, 2-8 parts additive, and 5-12 parts dispersant. The structural formula of the nitrogen-phosphorus flame retardant compound is as follows: .

6. A high flash point fire-retardant coating according to claim 5, characterized in that, The epoxy resin is epoxy resin 828, epoxy resin 815, or epoxy resin C. 14 H 20 O4.

7. The high flash point fire-retardant coating according to claim 5, characterized in that, The dispersant is water, and the epoxy resin is an aqueous epoxy resin.

8. The high flash point fire-retardant coating according to claim 5, characterized in that, The flame retardant is a mixture of alumina, cobalt dioxide, and pentaerythritol in a mass ratio of 1:1:20; the curing agent is a mixture of ethylenediamine and diethylenetriamine in a mass ratio of 1:

1.

9. A method for preparing the high flash point fire-retardant coating according to any one of claims 5-8, characterized in that, Includes the following steps: a. A pre-formed coating is obtained by mixing epoxy resin, nitrogen-phosphorus flame retardant compound, flame retardant additive, auxiliaries and dispersant; b. Mix the pre-made coating with a curing agent to obtain a high flash point fire-retardant coating.

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