Weather-resistant flame-retardant protective coating and preparation method thereof

Abstract

The present application relates to the technical field of paint, and more particularly to a weather-resistant flame-retardant protective paint and a preparation method thereof.The paint comprises the following raw materials by weight: 60-70 parts of epoxy resin, 10-15 parts of urea-formaldehyde resin, 5-10 parts of reinforcing fiber, 5-10 parts of flame retardant, 3-8 parts of heat-resistant filler, 3-5 parts of curing agent, 1-3 parts of leveling agent, and 30-40 parts of solvent.The paint has excellent mechanical strength, flame-retardant performance, high-temperature resistance, and long-term corrosion resistance and weather resistance.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a weather-resistant and flame-retardant protective coating and its preparation method. Background Technology

[0002] In aerospace, outdoor power equipment, and rail transportation, equipment housings and structural components are subjected to complex service environments involving alternating high temperatures, humid corrosion, and the risk of open flame. This places stringent demands on the flame retardancy, heat resistance, mechanical strength, and weather resistance and corrosion protection properties of surface protective coatings. Epoxy resin coatings, due to their excellent adhesion, good chemical corrosion resistance, and low curing shrinkage, are one of the most widely used substrate systems in the field of protective coatings.

[0003] However, existing conventional epoxy protective coatings still have many technical shortcomings, making them difficult to adapt to high-end protection scenarios. Firstly, pure epoxy resin itself is a flammable material, easily pyrolyzing and burning at high temperatures, releasing large amounts of smoke, and cannot meet high fire resistance requirements. Conventional additive inorganic flame retardants suffer from problems such as large dosage and easy agglomeration, which degrades the mechanical properties and density of the coating, making it difficult to balance flame retardancy and protective performance. Secondly, inorganic heat-resistant fillers such as boron nitride have strong surface inertness and poor interfacial compatibility with the epoxy resin matrix, easily forming interfacial defects and micropores within the coating. This weakens the heat-resistant barrier effect and provides a penetration path for water vapor and corrosive media, leading to a decrease in the coating's water resistance, salt spray resistance, and damp heat aging resistance, and making it prone to powdering and peeling during high-temperature service. Thirdly, glass fiber, as a commonly used reinforcing component, has a smooth surface and low reactivity, resulting in weak interfacial bonding with the epoxy matrix, making it prone to interfacial delamination. This prevents it from fully exerting its mechanical reinforcement effect and from synergistically improving the coating's flame retardancy and weather resistance.

[0004] Therefore, developing a protective coating that combines excellent flame retardancy, heat resistance, mechanical strength, and weather resistance and corrosion resistance has significant engineering application value. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a weather-resistant and flame-retardant protective coating that combines excellent mechanical strength, flame retardant properties, high temperature resistance, and long-term anti-corrosion and weather-resistant properties.

[0006] The second objective of this invention is to provide a method for preparing a weather-resistant and flame-retardant protective coating, which is stable and easy to operate.

[0007] One of the objectives of this invention is achieved through the following technical solution: A weather-resistant and flame-retardant protective coating comprises the following raw materials in parts by weight: 60-70 parts epoxy resin, 10-15 parts urea-formaldehyde resin, 5-10 parts reinforcing fiber, 5-10 parts flame retardant, 3-8 parts heat-resistant filler, 3-5 parts curing agent, 1-3 parts leveling agent, and 30-40 parts solvent. The preparation process of the heat-resistant filler is as follows: (1) Add activated boron nitride to an aqueous ethanol solution, then add a silane coupling agent, heat the reaction and purify to obtain boron nitride containing amino groups; (2) Add the amino-containing boron nitride to N,N-dimethylformamide, then add 2,6,10-triphenyltrimethylene acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, react under an inert gas atmosphere, then add myristol, heat and continue the reaction, purify, and obtain the product.

[0008] Preferably, in step (1), the ratio of activated boron nitride, silane coupling agent, and ethanol aqueous solution is 1g:(8-10)g:(40-50)mL; the silane coupling agent is KH550; the volume fraction of the ethanol aqueous solution is 80%; and the heating reaction temperature is 40-50℃ and the time is 3-5h.

[0009] Preferably, the method for preparing the activated boron nitride is as follows: Boron nitride is added to a nitric acid solution, heated and stirred, and then purified to obtain the product.

[0010] Preferably, the ratio of boron nitride to nitric acid solution is 1g:(15-20)mL; the mass fraction of nitric acid solution is 60-70%; and the heating and stirring temperature is 70-80℃ for 1-2h.

[0011] Preferably, in step (2), the mass ratio of the amino-containing boron nitride, 2,6,10-triphenyltrimethylene acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and myristol is 1:(1.5-2):(0.03-0.06):(0.02-0.04):(0.5-1.2); the reaction temperature is 50-60℃, and the reaction time is 3-5h; the reaction is continued at 80-90℃ for 5-8h.

[0012] Preferably, the preparation process of the reinforcing fiber is as follows: A. Glass fibers are added to hydrogen peroxide, refluxed, and then purified to obtain pretreated glass fibers; B. Add the pretreated glass fiber to water, then add 2-aminoethylphosphonic acid, heat to react, and then purify to obtain the final product.

[0013] Preferably, in step A, the ratio of glass fiber to hydrogen peroxide is 1g:(25-30)mL; the mass fraction of hydrogen peroxide is 30%; and the reflux reaction time is 3-5h.

[0014] Preferably, the mass ratio of the pretreated glass fiber to 2-aminoethylphosphonic acid in step B is 1:(0.5-0.8); the heating reaction temperature is 50-60℃ and the time is 4-7h.

[0015] Preferably, the flame retardant is aluminum hydroxide or zinc borate; the curing agent is an epoxy resin curing agent; the leveling agent is BYK-306; and the solvent is composed of methyl ethyl ketone and xylene in a volume ratio of 3:7.

[0016] The second objective of this invention is achieved by the following technical solution: The preparation method of the above-mentioned weather-resistant and flame-retardant protective coating includes the following steps: S1. Add epoxy resin, urea-formaldehyde resin, flame retardant, leveling agent, and reinforcing fiber to 1 / 2-2 / 3 of the solvent, mix evenly, and obtain component 1; S2. Add the heat-resistant filler and curing agent to the remaining solvent and mix well to obtain component 2; S3. Mix component 1 and component 2 evenly.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a weather-resistant and flame-retardant protective coating, which has excellent mechanical strength, flame retardant properties, high temperature resistance, and long-term anti-corrosion and weather-resistant properties.

[0018] 2. This invention improves the heat resistance and long-term corrosion and weather resistance of coatings by introducing a heat-resistant filler obtained through a specific modification method. The heat-resistant filler uses activated boron nitride as the inorganic heat-resistant matrix. First, it undergoes amylation modification using the silane coupling agent KH550, followed by amidation grafting with 2,6,10-triphenyltrimethylene acid, anchoring the high-rigidity, high-heat-resistant triphenyltrimethylene fused-ring aromatic structure onto the boron nitride surface. The grafted fused-ring aromatic heat-resistant groups and the inorganic heat-resistant skeleton of boron nitride form an inorganic-organic synergistic heat-resistant system, which can promote the formation of a dense carbonized layer at high temperatures, effectively blocking heat flow and significantly improving the heat resistance of the epoxy resin coating. Subsequently, long-chain alkyl hydrophobic groups are introduced through myristyl alcohol esterification, effectively reducing the surface polarity of the filler, significantly improving its interfacial compatibility with the epoxy resin matrix, promoting uniform dispersion of the filler in the coating system, avoiding coating defects caused by agglomeration, and thus comprehensively improving the high-temperature service performance of the coating.

[0019] 3. This invention improves the mechanical strength, flame retardant properties, high-temperature resistance, and long-term corrosion and weather resistance of the coating by introducing reinforcing fibers. First, hydrogen peroxide is used to pretreat the glass fibers to remove the inert layer on their surface, increase the specific surface area, and fully expose the active silanol sites on the fiber surface. Then, the phosphonic acid groups in the 2-aminoethylphosphonic acid molecule undergo a dehydration condensation reaction with the silanol groups enriched on the fiber surface, forming stable Si-OP covalent bonds and constructing an organic functional layer containing phosphorus and nitrogen elements on the fiber surface. The highly active amino functional groups exposed on the modified fiber surface can undergo ring-opening crosslinking reactions with the epoxy groups in the epoxy resin, forming strong chemical bonds at the fiber-matrix interface. This chemical cross-linking interface not only enables the reinforcing fibers to form a dense three-dimensional reinforcing network within the coating, significantly improving the coating's mechanical strength and impact resistance, but also allows the stable phosphonic acid modified layer to effectively fill the coating's micropores, enhancing its overall density and preventing the penetration and diffusion of moisture and corrosive media. This significantly strengthens the coating's corrosion resistance, water resistance, and resistance to damp heat aging. Furthermore, the phosphorus and nitrogen elements on the fiber surface constitute a synergistic flame-retardant system, which promotes char formation and releases non-combustible gases during combustion, endowing the epoxy resin coating with excellent flame-retardant and smoke-suppressing properties and high-temperature thermal stability. Attached Figure Description

[0020] Figure 1 Here is a SEM image of the reinforcing fiber prepared in Example 1; Figure 2 This is a SEM image of the heat-resistant filler prepared in Example 4. Detailed Implementation

[0021] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0022] In this invention, the glass fiber has a diameter of 9-13µm and a length of 1-6mm; the solvent consists of butanone and xylene in a volume ratio of 3:7.

[0023] Preparation Example 1 The preparation process of the reinforcing fiber is as follows: A. Glass fiber was added to a three-necked flask equipped with a constant pressure dropping funnel, a reflux condenser and a thermometer at a ratio of 1g:28mL. Then, 30% hydrogen peroxide was slowly added dropwise through the constant pressure dropping funnel. After stirring and mixing evenly, the mixture was heated and refluxed for 4 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain pretreated glass fiber. B. With a mass ratio of 1:0.7 of pretreated glass fiber to 2-aminoethylphosphonic acid, the pretreated glass fiber was added to water, ultrasonically dispersed evenly, and then 2-aminoethylphosphonic acid was added. The mixture was reacted at 55°C for 6 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the final product.

[0024] Preparation Example 2 The preparation process of the reinforcing fiber is as follows: A. Glass fiber was added to a three-necked flask equipped with a constant pressure dropping funnel, a reflux condenser and a thermometer at a ratio of 1g:30mL. Then, 30% hydrogen peroxide was slowly added dropwise through the constant pressure dropping funnel. After stirring and mixing evenly, the mixture was heated and refluxed for 5 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain pretreated glass fiber. B. With a mass ratio of 1:0.8 of pretreated glass fiber to 2-aminoethylphosphonic acid, the pretreated glass fiber was added to water, ultrasonically dispersed evenly, and then 2-aminoethylphosphonic acid was added. The mixture was reacted at 60°C for 4 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the final product.

[0025] Preparation Example 3 The preparation process of the reinforcing fiber is as follows: A. Glass fiber was added to a three-necked flask equipped with a constant pressure dropping funnel, a reflux condenser and a thermometer at a ratio of 1g:25mL. Then, 30% hydrogen peroxide was slowly added dropwise through the constant pressure dropping funnel. After stirring and mixing evenly, the mixture was heated and refluxed for 3 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain pretreated glass fiber. B. With a mass ratio of 1:0.5 of pretreated glass fiber to 2-aminoethylphosphonic acid, the pretreated glass fiber was added to water, ultrasonically dispersed evenly, and then 2-aminoethylphosphonic acid was added. The mixture was reacted at 50°C for 7 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the final product.

[0026] Preparation Example 4 The preparation process of the heat-resistant filler is as follows: (1) Boron nitride was added to a 65% nitric acid solution at a ratio of 1 g to 17 mL, stirred at 75 °C for 1.5 h, centrifuged, washed with deionized water until neutral, and dried under vacuum to obtain activated boron nitride; Boron nitride was added to an 80% ethanol aqueous solution at a ratio of 1 g to 9 g to 45 mL, KH550 (γ-aminopropyltriethoxysilane) was added, and reacted at 45 °C for 4 h. After the reaction was completed, the solution was centrifuged, washed, and dried to obtain boron nitride containing amino groups. (2) With the mass ratio of amino-containing boron nitride, 2,6,10-triphenyltrimethylene acid, EDC, NHS and myristol being 1:1.8:0.05:0.03:1, the above-mentioned amino-containing boron nitride was added to DMF (N,N-dimethylformamide), ultrasonically dispersed evenly, and then 2,6,10-triphenyltrimethylene acid, EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) were added. The reaction was carried out under a nitrogen atmosphere at 55°C for 4 hours. Then myristol was added, the temperature was raised to 85°C and the reaction was continued for 7 hours. After the reaction was completed, the mixture was centrifuged, washed, and vacuum dried to obtain the product.

[0027] Preparation Example 5 The preparation process of the heat-resistant filler is as follows: (1) Boron nitride was added to a 70% nitric acid solution at a ratio of 1 g to 20 mL, stirred at 80 °C for 1.5 h, centrifuged, washed with deionized water until neutral, and dried under vacuum to obtain activated boron nitride; Boron nitride was added to an 80% ethanol aqueous solution at a ratio of 1 g to 10 g to 50 mL, KH550 was added, and reacted at 50 °C for 3 h. After the reaction was completed, the solution was centrifuged, washed, and dried to obtain boron nitride containing amino groups. (2) With the mass ratio of amino-containing boron nitride, 2,6,10-triphenyltrimethylene acid, EDC, NHS and myristol being 1:2:0.06:0.04:1.2, the above-mentioned amino-containing boron nitride was added to DMF and ultrasonically dispersed evenly. Then, 2,6,10-triphenyltrimethylene acid, EDC and NHS were added, and the reaction was carried out at 60°C for 3 hours under a nitrogen atmosphere. Then, myristol was added, and the temperature was raised to 90°C and the reaction was continued for 5 hours. After the reaction was completed, the mixture was centrifuged, washed, and vacuum dried to obtain the product.

[0028] Preparation Example 6 The preparation process of the heat-resistant filler is as follows: (1) Boron nitride was added to a 60% nitric acid solution at a ratio of 1 g: 15 mL, stirred at 70 °C for 2 h, centrifuged, washed with deionized water until neutral, and dried under vacuum to obtain activated boron nitride; Boron nitride was added to an 80% ethanol aqueous solution at a ratio of 1 g: 8 g: 40 mL, KH550 was added, reacted at 40 °C for 5 h, centrifuged, washed, and dried after the reaction was completed to obtain boron nitride containing amino groups; (2) With the mass ratio of amino-containing boron nitride, 2,6,10-triphenyltrimethylene acid, EDC, NHS and myristol being 1:1.5:0.03:0.02:0.5, the above-mentioned amino-containing boron nitride was added to DMF and ultrasonically dispersed evenly. Then, 2,6,10-triphenyltrimethylene acid, EDC and NHS were added, and the reaction was carried out at 50°C for 5 hours under a nitrogen atmosphere. Then, myristol was added, and the temperature was raised to 80°C and the reaction was continued for 8 hours. After the reaction was completed, the mixture was centrifuged, washed, and vacuum dried to obtain the final product.

[0029] Example 1 A weather-resistant and flame-retardant protective coating comprises the following raw materials in parts by weight: 66 parts epoxy resin, 14 parts urea-formaldehyde resin, 9 parts reinforcing fiber of Preparation Example 1, 8 parts zinc borate, 5 parts heat-resistant filler of Preparation Example 4, 4 parts epoxy resin curing agent, 2 parts BYK-306, and 37 parts solvent.

[0030] The preparation method of the above-mentioned weather-resistant and flame-retardant protective coating includes the following steps: S1. Add epoxy resin, urea-formaldehyde resin, zinc borate, BYK-306, and reinforcing fiber to 3 / 5 of the solvent, stir at 300 rpm for 20 min, and then stir at 800 rpm for 40 min to obtain component 1; S2. Add the heat-resistant filler and epoxy resin curing agent to the remaining solvent, and stir at 800 rpm for 40 min to obtain component 2; S3. Stir the above components 1 and 2 at 500 rpm for 40 minutes.

[0031] Example 2 A weather-resistant and flame-retardant protective coating comprises the following raw materials in parts by weight: 70 parts epoxy resin, 15 parts urea-formaldehyde resin, 10 parts reinforcing fiber of Preparation Example 2, 10 parts zinc borate, 8 parts heat-resistant filler of Preparation Example 5, 5 parts epoxy resin curing agent, 3 parts BYK-306, and 40 parts solvent.

[0032] The preparation method of the above-mentioned weather-resistant and flame-retardant protective coating includes the following steps: S1. Add epoxy resin, urea-formaldehyde resin, zinc borate, BYK-306, and reinforcing fiber to 2 / 3 of the solvent, stir at 300 rpm for 20 min, and then stir at 800 rpm for 40 min to obtain component 1; S2. Add the heat-resistant filler and epoxy resin curing agent to the remaining solvent, and stir at 800 rpm for 40 min to obtain component 2; S3. Stir the above components 1 and 2 at 500 rpm for 40 minutes.

[0033] Example 3 A weather-resistant and flame-retardant protective coating comprises the following raw materials in parts by weight: 60 parts epoxy resin, 10 parts urea-formaldehyde resin, 5 parts reinforcing fiber of Preparation Example 3, 5 parts aluminum hydroxide, 3 parts heat-resistant filler of Preparation Example 6, 3 parts epoxy resin curing agent, 1 part BYK-306, and 30 parts solvent.

[0034] The preparation method of the above-mentioned weather-resistant and flame-retardant protective coating includes the following steps: S1. Add epoxy resin, urea-formaldehyde resin, aluminum hydroxide, BYK-306, and reinforcing fiber to 1 / 2 of the solvent, stir at 300 rpm for 20 min, and then stir at 800 rpm for 40 min to obtain component 1; S2. Add the heat-resistant filler and epoxy resin curing agent to the remaining solvent, and stir at 800 rpm for 40 min to obtain component 2; S3. Stir the above components 1 and 2 at 500 rpm for 40 minutes.

[0035] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the heat-resistant filler in Preparation Example 4 was replaced with boron nitride containing amino groups, and the preparation method of boron nitride containing amino groups was the same as that in Preparation Example 4.

[0036] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the reinforcing fiber in Example 1 was replaced with glass fiber.

[0037] Experimental Example 1 Scanning electron microscopy (SEM) was performed on the reinforcing fiber of Preparation Example 1 and the heat-resistant filler of Preparation Example 4. The results are as follows: Figure 1-2 As shown.

[0038] Figure 1 This is a SEM image of the reinforcing fibers prepared in Example 1. (Observation) Figure 1 It can be seen that the reinforced fiber obtained after modification still maintains the complete fiber main structure, and the surface roughness is improved, showing a textured surface.

[0039] Figure 2 This is a SEM image of the heat-resistant filler prepared in Example 4. (Observation) Figure 2 It can be seen that after multiple steps of surface modification, such as amination modification, grafting of triphenylene fused ring structure and long-chain alkyl end capping, the surface of the heat-resistant filler exhibits a rough coating morphology and no obvious agglomeration phenomenon.

[0040] Experimental Example 2 The performance of the coatings prepared in the examples and comparative examples was tested, as follows: Impact resistance: Tested according to GB / T 1732-2020, the results are shown in Table 1; Flame retardant performance: Tested according to GB / T 2406.2-2009, the results are shown in Table 1; Adhesion: The test was conducted in accordance with GB / T 9286-2021, and the results are shown in Table 1. Heat resistance: The results of irradiation under an 800℃ quartz lamp for 30 minutes are shown in Table 1. Water resistance: The test was conducted according to Method A of GB / T 1733-1993. The test temperature was 40℃ and the test time was 10 days. The results are shown in Table 1. Corrosion resistance: Tested according to GB / T 10125-2021 for 2200 hours, the results are shown in Table 1; Moisture and heat resistance: The test was conducted in accordance with GB / T 1740-2007 for 600 hours, and the results are shown in Table 1.

[0041] Table 1 The test results in Table 1 show that the present invention can improve the overall performance of the coating by combining heat-resistant filler with reinforcing fiber.

[0042] Compared to Example 1, Comparative Example 1 exhibits decreased heat resistance, corrosion resistance, water resistance, and resistance to damp heat aging. This is because Comparative Example 1 uses only boron nitride containing amino groups, without grafting the fused-ring structure of 2,6,10-triphenyltrimethylene acid or end-capping the alkyl chain of myristol. The lack of highly rigid triphenyltrimethylene fused-ring aromatic heat-resistant groups prevents the formation of an inorganic-organic synergistic heat-resistant system with the boron nitride inorganic framework, significantly weakening the filler's char-forming ability and thermal barrier effect at high temperatures. Simultaneously, the absence of long-chain alkyl hydrophobic groups results in high filler surface polarity, poor interfacial compatibility with the resin matrix, difficulty in uniform dispersion, and easy formation of interfacial defects within the coating, leading to a decrease in the coating's water resistance, corrosion resistance, and resistance to damp heat aging.

[0043] Compared to Example 1, Comparative Example 2 exhibits decreased mechanical strength, flame retardancy, heat resistance, corrosion resistance, water resistance, and resistance to damp heat aging. This is because Comparative Example 2 directly utilizes unmodified glass fiber. The fiber surface lacks active functional groups, preventing effective chemical cross-linking with the epoxy resin matrix. The weak interfacial bonding makes the fiber easily pulled out or peeled off when subjected to external impact, significantly reducing mechanical strength. Furthermore, the unmodified glass fiber surface lacks phosphorus and nitrogen-containing flame-retardant functional groups, failing to provide a phosphorus-nitrogen synergistic flame-retardant effect and limiting the improvement of the coating's flame retardant performance. More critically, the smooth fiber surface and the resin matrix have significant interfacial gaps. These microscopic defects become rapid penetration channels for water vapor, oxygen, and corrosive ions, compromising the coating's density and leading to a decrease in heat resistance, corrosion resistance, water resistance, and resistance to damp heat aging.

[0044] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A weather-resistant and flame-retardant protective coating, characterized in that, The raw materials include the following parts by weight: 60-70 parts epoxy resin, 10-15 parts urea-formaldehyde resin, 5-10 parts reinforcing fiber, 5-10 parts flame retardant, 3-8 parts heat-resistant filler, 3-5 parts curing agent, 1-3 parts leveling agent, and 30-40 parts solvent. The preparation process of the heat-resistant filler is as follows: (1) Add activated boron nitride to an aqueous ethanol solution, then add a silane coupling agent, heat the reaction and purify to obtain boron nitride containing amino groups; (2) Add the amino-containing boron nitride to N,N-dimethylformamide, then add 2,6,10-triphenyltrimethylene acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, react under an inert gas atmosphere, then add myristol, heat and continue the reaction, purify, and obtain the product.

2. The weather-resistant and flame-retardant protective coating as described in claim 1, characterized in that, In step (1), the ratio of activated boron nitride, silane coupling agent, and ethanol aqueous solution is 1g:(8-10)g:(40-50)mL; the silane coupling agent is KH550; the volume fraction of the ethanol aqueous solution is 80%; the heating reaction temperature is 40-50℃ and the time is 3-5h.

3. The weather-resistant and flame-retardant protective coating as described in claim 2, characterized in that, The method for preparing the activated boron nitride is as follows: Boron nitride is added to a nitric acid solution, heated and stirred, and then purified to obtain the product.

4. The weather-resistant and flame-retardant protective coating as described in claim 3, characterized in that, The ratio of boron nitride to nitric acid solution is 1g:(15-20)mL; the mass fraction of nitric acid solution is 60-70%; the heating and stirring temperature is 70-80℃, and the time is 1-2h.

5. The weather-resistant and flame-retardant protective coating as described in claim 1, characterized in that, In step (2), the mass ratio of the amino-containing boron nitride, 2,6,10-triphenyltrimethylene acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and myristol is 1:(1.5-2):(0.03-0.06):(0.02-0.04):(0.5-1.2); the reaction temperature is 50-60℃, and the reaction time is 3-5h; the reaction is continued at 80-90℃ for 5-8h.

6. The weather-resistant and flame-retardant protective coating as described in claim 1, characterized in that, The preparation process of the reinforcing fiber is as follows: A. Glass fibers are added to hydrogen peroxide, refluxed, and then purified to obtain pretreated glass fibers; B. Add the pretreated glass fiber to water, then add 2-aminoethylphosphonic acid, heat to react, and then purify to obtain the final product.

7. The weather-resistant and flame-retardant protective coating as described in claim 6, characterized in that, In step A, the ratio of glass fiber to hydrogen peroxide is 1g:(25-30)mL; the mass fraction of hydrogen peroxide is 30%; and the reflux reaction time is 3-5h.

8. The weather-resistant and flame-retardant protective coating as described in claim 6, characterized in that, In step B, the mass ratio of the pretreated glass fiber to 2-aminoethylphosphonic acid is 1:(0.5-0.8); the heating reaction temperature is 50-60℃, and the time is 4-7h.

9. The weather-resistant and flame-retardant protective coating as described in claim 1, characterized in that, The flame retardant is aluminum hydroxide or zinc borate; the curing agent is an epoxy resin curing agent; the leveling agent is BYK-306; and the solvent is composed of methyl ethyl ketone and xylene in a volume ratio of 3:

7.

10. A method for preparing a weather-resistant and flame-retardant protective coating according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Add epoxy resin, urea-formaldehyde resin, flame retardant, leveling agent, and reinforcing fiber to 1 / 2-2 / 3 of the solvent, mix evenly, and obtain component 1; S2. Add the heat-resistant filler and curing agent to the remaining solvent and mix well to obtain component 2; S3. Mix component 1 and component 2 evenly.

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