Environment-aging-resistant composite nano protective coating and preparation method thereof

Abstract

The invention discloses an environment-aging-resistant composite nano protective coating and a preparation method thereof, and relates to the technical field of functional coatings. The preparation method comprises the following steps: blending a hydroxyl-terminated fluorine-containing polyurethane prepolymer, methyl phenyl vinyl silicone resin and a solvent, adding HMDS (hexamethyldisilazane) modified mesoporous silica, an ultraviolet light absorber and dendritic phosphorus-containing fluorosilicone resin for blending, adding barium strontium titanate / boron nitride core-shell particles for blending, adding a curing agent for curing, adding a curing agent for curing, and finally adding a curing agent for curing. And adding an HDI tripolymer curing agent and blending to obtain the composite nano protective coating. The coating prepared by the invention has the effects of high frequency, low loss, super-hydrophobicity, salt mist resistance, high and low temperature impact resistance, efficient flame retardance, damp-heat aging stability, strong adhesive force, ultraviolet aging resistance and high insulation resistance.

Description

Technical Field

[0001] This invention relates to the field of functional coatings technology, specifically to composite nano-protective coatings resistant to environmental aging and their preparation methods. Background Technology

[0002] As human society enters an era of rapid information technology development, electronic products and electrical equipment are indispensable in everything from critical national defense sectors like aerospace and rail transportation to everyday life. In specific applications such as power grids, military electronic equipment, and naval equipment, products and components operate in harsh environments with high temperatures, high humidity, and high salt spray. As electronic components are increasingly assembled with higher densities and narrower spacing, they become highly sensitive to their environment, dramatically increasing the risk of malfunction or failure. These demanding working environments lead to a decline in the performance and lifespan of electronic components and products. Therefore, to ensure the stability of electronic products and extend their lifespan, a conformal coating, primarily composed of polymers or resins, is applied to the surface of core components—printed circuit boards and their parts. This conformal coating, applied through processes such as spraying, brushing, or dipping, provides high insulation protection and acts as a barrier.

[0003] Currently, conformal coatings are used to protect electronic circuit boards, providing protection against salt spray, damp heat, and mold. However, with the increasing number of high-frequency electronic components on circuit boards and their application under high-frequency cables, traditional conformal coatings are no longer sufficient. Under high-frequency current surges, the coating film suffers significant wear, failing to guarantee the stability and safety of the circuit board during long-term operation. Furthermore, the high temperatures generated during soldering also cause considerable wear on the coating film. To improve the product's environmental adaptability and ensure its normal operation in harsh environments, there is an urgent need for a protective coating that combines high-frequency performance, conformal coating properties, high and low temperature resistance, and high insulation performance. This coating must maintain good insulation and conformal coating properties at high frequencies of 60-150MHz. Summary of the Invention

[0004] The purpose of this invention is to provide a composite nano-protective coating resistant to environmental aging and its preparation method, thereby solving the following technical problems: Existing conformal coatings cannot be used properly in high-frequency or high- and low-temperature environments.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for preparing a composite nano-protective coating resistant to environmental aging includes the following steps: blending hydroxyl-terminated fluorinated polyurethane prepolymer, methylphenyl vinyl silicone resin, and solvent; adding HMDS-modified mesoporous silica, ultraviolet absorber, and dendritic phosphorus-containing fluorosilicone resin; adding barium strontium titanate / boron nitride core-shell particles; and adding HDI trimer curing agent to obtain a composite nano-protective coating. The dendritic phosphorus-containing fluorosilicone resin is prepared by esterification of PMMA-NH2 with diethyl chlorophosphate, quaternization of perfluorohexyl ethyl iodide to introduce a perfluorinated chain, and silane coupling reaction of propyltrimethoxysilane.

[0006] As a further aspect of the present invention, the preparation method of the dendritic phosphorus-containing fluorosilicone resin includes the following steps: S1: Under a nitrogen atmosphere, PMMA-NH2, N,N-dimethylformamide, and triethylamine are added to reactor A. The temperature is controlled at 0-5℃. Diethyl chlorophosphate is added. The temperature is controlled at 40-60℃. The reaction is carried out under stirring for 12-24 hours. The mixture is filtered, and the filtrate is poured into deionized water to precipitate. The precipitate is collected by centrifugation, washed, and dried to obtain phosphorylated PMMA. S2: Under a nitrogen atmosphere, phosphated PMMA and N,N-dimethylformamide were added to reactor B, along with potassium carbonate and perfluorohexylethyl iodide. The reaction was carried out at a temperature of 80-100℃ with stirring for 24-48 hours. The mixture was filtered, and the filtrate was poured into deionized water to precipitate. The precipitate was then centrifuged and dried to obtain the intermediate product. S3: Under a nitrogen atmosphere, the intermediate product, N,N-dimethylformamide, and propyltrimethoxysilane isocyanate are added to reactor C. The temperature is controlled at 40-60℃ and the reaction is maintained at this temperature for 12-24 hours with stirring. The N,N-dimethylformamide is removed by vacuum distillation, the precipitate is reprecipitated, and the product is dried to obtain dendritic phosphorus-containing fluorosilicone resin.

[0007] As a further aspect of the present invention: the addition ratio of PMMA-NH2, N,N-dimethylformamide, triethylamine, and diethyl chlorophosphate in S1 is 10g: 100-200mL: 1.5-2.4g: 1.6-2.7g; The addition ratio of phosphorylated PMMA, N,N-dimethylformamide, potassium carbonate, and perfluorohexylethyl iodide in S2 is 10g: 150-200mL: 2-3g: 6-9g; The addition ratio of intermediate product, N,N-dimethylformamide, and propyltrimethoxysilane in S3 is 10g: 150-200mL: 2.2-3.7g.

[0008] As a further aspect of the present invention, the preparation method of PMMA-NH2 includes the following steps: 6g of ethylenediamine and 50-100mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0-5℃. 34.4-38.7g of methyl acrylate was added and the temperature was controlled at 25-35℃. The reaction was carried out under stirring for 24-48h. Excess methyl acrylate and methanol were removed by vacuum distillation to obtain the intermediate. The intermediate and 50-100 mL of methanol were added to a reaction flask for dispersion. The temperature was controlled at 0-5℃. 48-60 g of ethylenediamine was added, and the temperature was controlled at 25-35℃. The reaction was carried out under stirring for 48-72 h. Excess ethylenediamine and methanol were removed by vacuum distillation to obtain PMMA-NH2.

[0009] As a further aspect of the present invention, the method for preparing barium strontium titanate / boron nitride core-shell particles includes the following steps: A1: Tetrabutyl titanate, anhydrous ethanol (component 1), and acetylacetone are dispersed in a reaction flask; barium acetate, strontium acetate, and anhydrous ethanol (component 2) are mixed and added to the reaction flask; glacial acetic acid and deionized water are added, and the mixture is stirred at room temperature for 3-6 hours to obtain a sol; the sol is transferred to an autoclave, heated to 160-180℃, and kept at that temperature for 12-24 hours; the mixture is then washed, dried, pulverized, and calcined to obtain barium strontium titanate powder. A2: Add barium strontium titanate powder and anhydrous ethanol to a reaction flask, adjust the pH to 9-10, add tetraethyl orthosilicate, deionized water and anhydrous ethanol to the reaction flask, control the temperature at 40-60℃, keep warm and stir for 5-10 hours, centrifuge, wash and dry to obtain barium strontium titanate powder coated with silica. A3: Add boric acid, urea, anhydrous ethanol and water to a reaction flask and disperse. Add barium strontium titanate powder coated with silica and disperse. Stir at room temperature for 12-24 hours. Remove anhydrous ethanol and water by rotary evaporation. Dry, calcine, etch, wash with water, and dry again to obtain BST@BN core-shell particles. A4: Mix KH550, ethanol, and water, add BST@BN particles for dispersion, control the temperature at 60-80℃, stir and reflux for 2-4 hours, centrifuge, wash with ethanol, and dry to obtain barium strontium titanate / boron nitride core-shell particles.

[0010] As a further embodiment of the present invention: the addition ratio of tetrabutyl titanate, anhydrous ethanol component one, acetylacetone, barium acetate, strontium acetate, anhydrous ethanol component two, glacial acetic acid, and deionized water in A1 is 3.4g: 20-30mL: 1-2g: 1.66-1.92g: 0.54-0.75g: 40-60mL: 2-3mL: 1-2mL; The addition ratio of barium strontium titanate powder, anhydrous ethanol component III, tetraethyl orthosilicate, deionized water, and anhydrous ethanol component IV in A2 is 10g: 80-160mL: 5-10g: 5-10mL: 20-40mL. In A3, the addition ratio of boric acid, urea, anhydrous ethanol, water, and barium strontium titanate powder coated with silica is 2.5-5g: 7.5-12.5g: 100-200mL: 5-10mL: 5g; The addition ratio of KH550, ethanol, water, and BST@BN particles in A4 is 0.25-0.50g: 50-100mL: 1-2mL: 5g; The specific steps for calcination in A1 are as follows: control the heating rate to 1-2℃ / min to raise the temperature to 330-350℃ and hold for 1-1.5h; control the heating rate to 2-5℃ / min to raise the temperature to 600-650℃ and hold for 2-4h. The specific drying steps in A3 are as follows: control the temperature at 60-80℃ and dry for 6-12 hours, then treat in nitrogen at 150-160℃ for 1-2 hours. The specific calcination steps in A3 are as follows: In an argon atmosphere, the temperature is increased to 300-330℃ at a rate of 5℃ / min; in a mixture of argon and ammonia with a volume ratio of 4:1, the temperature is increased to 850-900℃ at a rate of 10℃ / min and held for 3 hours; in an argon atmosphere, the temperature is decreased to 550-600℃ at a rate of 2℃ / min; in an argon atmosphere, the temperature is decreased to room temperature at a rate of 5-10℃ / min.

[0011] As a further embodiment of the present invention, the preparation method of HMDS modified mesoporous silica includes the following steps: under a nitrogen atmosphere, 10g of mesoporous silica and 80-150mL of toluene are mixed, 2-5g of hexamethyldisilazane is added, the temperature is controlled at 60-90℃, and the mixture is stirred and refluxed for 4-12h. After washing and drying, HMDS modified mesoporous silica is obtained.

[0012] As a further embodiment of the present invention, the preparation method of mesoporous silica includes the following steps: 2-5g of cetyltrimethylammonium bromide, 20-40mL of deionized water, and 60-100mL of anhydrous ethanol are mixed, ammonia water is added to adjust the pH to 9-10, the temperature is controlled at 30-50℃, 10-20g of tetraethyl orthosilicate is added, the mixture is stirred and kept at a constant temperature for 3-6h, allowed to stand for aging for 12-24h, dried at 80-100℃ for 12-24h, and calcined (heated at a rate of 2-5℃ / min to 500-600℃ and kept at that temperature for 4-6h) to obtain mesoporous silica.

[0013] As a further aspect of the present invention, the preparation method of the hydroxyl-terminated fluorinated polyurethane prepolymer includes the following steps: B1: Isophorone diisocyanate, dibutyltin dilaurate, and acetone are added to a reaction flask and dispersed. The temperature is controlled at 40-60℃. Hexafluorobutanol is added dropwise, and the reaction is maintained at this temperature for 2-4 hours. Diethanolamine is added dropwise, and the reaction is maintained at 0-5℃ for 1-3 hours. Acetone is removed by vacuum distillation to obtain a fluorinated diol with terminal hydroxyl groups. B2: Polytetrahydrofuran ether diol and hydroxyl-terminated fluorinated diol are dispersed in a reaction flask and the temperature is controlled at 70-90℃. Isophorone diisocyanate and dibutyltin dilaurate are added and the reaction is maintained at 70-90℃ for 2-4 hours. Then, 1,4-butanediol and propylene glycol methyl ether acetate are mixed and added to the reaction flask. The reaction is maintained at 70-80℃ for 1.5-3 hours to obtain hydroxyl-terminated fluorinated polyurethane prepolymer. The addition ratio of isophorone diisocyanate, dibutyltin dilaurate, acetone, hexafluoro-n-butanol, and 4.7-5.2g of diethanolamine in B1 is 10g:0.015-0.03g:5-10mL:7.8-8.6g; The addition ratio of polytetrahydrofuran ether diol, hydroxyl-terminated fluorinated diol, isophorone diisocyanate, dibutyltin dilaurate, 1,4-butanediol, and propylene glycol methyl ether acetate in B2 is 50-70g: 8-15g: 15-25g: 0.01-0.05g: 1-3g: 80-120g.

[0014] As a further aspect of the present invention: the preparation method of methylphenyl vinyl silicone resin includes the following steps: under a nitrogen atmosphere, 28-35g of methyltrimethoxysilane, 35-40g of diphenyldimethoxysilane, 20-25g of methylphenyldimethoxysilane, 5-10g of vinyltrimethoxysilane, and 1-5g of trimethylmethoxysilane are added to a reaction vessel and dispersed, the temperature is controlled at 30-45℃, 150-300mL of water and 300-600mL of toluene are added to the reaction vessel, hydrochloric acid is added to adjust the pH to 2-3, the temperature is controlled at 70-75℃, and the reaction is maintained at this temperature for 6- 9h; add 0.01-0.05g dibutyltin dilaurate, keep the reaction at the temperature for 2-4h; separate the organic layer, add sodium bicarbonate to neutralize the organic layer to neutral, filter, remove toluene, water and low-boiling substances under vacuum of 0.08-0.1MPa and 120-150℃, and dry; redissolve the dried resin material in toluene, add methyltrimethoxysilane (mass ratio of resin material to methyltrimethoxysilane is 100:5-10), reflux at 80-100℃ for 2-4h, remove toluene and low-boiling substances by vacuum distillation to obtain methylphenyl vinyl silicone resin.

[0015] As a further embodiment of the present invention: the composite nano-protective coating comprises the following raw materials in parts by weight: 35-45 parts by weight of hydroxyl-terminated fluorinated polyurethane prepolymer, 12-18 parts by weight of methylphenyl vinyl silicone resin, 20-28 parts by weight of solvent, 6-10 parts by weight of HMDS modified mesoporous silica, 0.3-0.8 parts by weight of ultraviolet absorber, 1.5-4.5 parts by weight of dendritic phosphorus-containing fluorosilicone resin, 4-12 parts by weight of barium strontium titanate / boron nitride core-shell particles, and 10-15 parts by weight of HDI trimer curing agent.

[0016] As a further aspect of the present invention: the solvent is composed of propylene glycol methyl ether acetate and propylene glycol methyl ether in a mass ratio of 15-20:5-10; the ultraviolet absorber is a benzotriazole ultraviolet absorber.

[0017] The environmentally resistant composite nano-protective coating is prepared by any of the above methods.

[0018] The beneficial effects of this invention are: The environmentally resistant composite nano-protective coating provided by this invention constructs an interpenetrating polymer network matrix by using hydroxyl-terminated fluorinated polyurethane prepolymer and methylphenyl vinyl silicone resin, and introduces two core functional additives: dendritic phosphorus-containing fluorosilicone resin and barium strontium titanate / boron nitride core-shell particles. It is also combined with HMDS-modified mesoporous silica, benzotriazole UV absorbers and HDI trimer curing agents to achieve high frequency and low loss, superhydrophobic salt spray resistance, high and low temperature shock resistance, high flame retardancy, stable damp heat aging, strong adhesion, UV aging resistance and high insulation resistance.

[0019] (1) High frequency, low dielectric loss and high insulation The strongly electronegative bound electron cloud of -CF3 in the hydroxyl-terminated fluorinated polyurethane prepolymer results in extremely high intrinsic volume resistivity of the matrix. The methylphenyl vinyl silicone resin, after dehydroxylation treatment, has an extremely low silanol content, reducing ionic conductivity pathways and ensuring stable insulation resistance, especially under humid conditions. The dense interpenetrating network structure, free of macroscopic defects and through-holes, inhibits electrochemical migration. This guarantees high insulation reliability of the coating under normal and humid aging conditions.

[0020] This application also incorporates barium strontium titanate / boron nitride core-shell particles and HMDS-modified mesoporous silica into the coating. Barium strontium titanate features an adjustable dielectric constant and low dielectric loss; boron nitride, being a layered material, exhibits good thermal conductivity, low dielectric loss, and high insulation. The core-shell structure achieves synergistic dielectric performance, ensuring stable dielectric performance at high frequencies while forming an electronic insulating barrier layer through boron nitride, reducing dielectric loss and leakage at high frequencies. Simultaneously, it enhances thermal conductivity, rapidly dissipating high-frequency operating heat and preventing performance degradation due to heat accumulation. The mesoporous structure of HMDS-modified mesoporous silica effectively reduces the increase in dielectric loss and decrease in insulation caused by moisture, ensuring insulation stability in high-frequency and humid environments.

[0021] (2) Superhydrophobicity and salt spray resistance The coating prepared in this application incorporates a hydroxyl-terminated fluorinated polyurethane prepolymer, a dendritic phosphorus-containing fluorosilicone resin, and a methylphenyl vinyl silicone resin. The -CF3 side chains of the hydroxyl-terminated fluorinated polyurethane prepolymer are directionally enriched on the coating surface during curing, reducing surface tension. The perfluorohexylethyl chains of the dendritic phosphorus-containing fluorosilicone resin also migrate to the surface and can dynamically reconstruct a hydrophobic layer after slight surface abrasion. HMDS-modified mesoporous silica is grafted with -Si(CH3)3 groups to eliminate hydrophilic silanol groups, preventing capillary adsorption of water molecules. The interpenetrating network structure formed by the hydroxyl-terminated fluorinated polyurethane prepolymer and the methylphenyl vinyl silicone resin is dense, effectively blocking water molecule permeation channels. Cl in salt spray... - Ions have difficulty penetrating hydrophobic surfaces, and even if a small amount enters, the covalent bonds formed between the coating and the substrate can prevent electrochemical corrosion.

[0022] (3) Resistance to high and low temperatures and thermal shock This application incorporates methylphenyl vinyl silicone resin into the coating. The main chain of methylphenyl vinyl silicone resin has a Si-O-Si bond energy that is much higher than that of C-C bonds, and the phenyl side chains further improve thermal oxidation stability, providing a high-temperature resistant framework. This application also adds barium strontium titanate / boron nitride core-shell particles. The barium strontium titanate core of these particles absorbs heat at high welding temperatures, reducing local peak temperatures; the boron nitride shell has a high in-plane thermal conductivity, enabling rapid diffusion of local hot spots along the surface, preventing heat concentration and ablation of the coating. The polytetrahydrofuran ether diol soft segment of the hydroxyl-terminated fluorinated polyurethane prepolymer added to the coating maintains flexibility at low temperatures, effectively releasing thermal stress. Furthermore, the interpenetrating polyurethane network formed by the methylphenyl vinyl silicone resin and the fluorinated polyurethane prepolymer allows the coating's coefficient of thermal expansion to match that of the substrate, reducing stress concentration during thermal cycling.

[0023] (4) High-efficiency flame retardant performance The dendritic phosphorus-containing fluorosilicone resin added to the coating of this application decomposes its phosphate ester units at high temperature to generate polyphosphoric acid, which promotes the dehydration and carbonization of the coating, forming a dense carbon layer to isolate oxygen and heat; the fluorine-containing segments decompose to generate ·CF2· free radicals, which capture H· and OH· free radicals in the combustion chain reaction and interrupt the gas phase combustion cycle; the silica migrates to the surface during combustion to form a ceramic protective layer, achieving heat insulation and oxygen isolation.

[0024] (5) Stability during damp heat aging The coating of this application incorporates a dendritic phosphorus-containing fluorosilicone resin. Its trimethoxysilane hydrolyzes under trace amounts of water catalysis to generate Si-OH, which forms covalent bonds with the matrix and solder resist layer. These covalent bonds exhibit significantly better hydrolysis resistance in wet conditions than traditional physical adsorption or hydrogen bonding. The dendritic structure provides single-molecule multi-arm anchoring, allowing a single molecule to simultaneously bond to multiple sites on the substrate. Even if individual bonds break, the overall adhesion remains intact. Simultaneously, the low surface energy of the fluorinated layer inhibits water molecule penetration to the interface, and the interpenetrating network structure resists the plasticizing effect of water molecules on the polymer, ensuring the stability of mechanical and electrical properties after hygrothermal aging.

[0025] (6) Excellent adhesion The terminal Si(OMe)3 of the dendritic phosphorus-containing fluorosilicone resin added to the coating of this application forms covalent bonds with the matrix and solder resist layer after hydrolysis, exhibiting high bond energy and hydrolysis resistance. Simultaneously, the reaction between the HDI trimer and the hydroxyl-terminated fluorinated polyurethane prepolymer generates urethane bonds, and the vinyl groups in the silicone resin can undergo hydrosilylation addition with hydrosilanes to form an internal cross-linked network, further enhancing the cohesive strength of the coating. The multi-arm structure of the dendritic molecules allows a single molecule to anchor multiple sites, achieving planar anchoring rather than point contact, resulting in a significant improvement in peel strength.

[0026] (7) Resistance to UV aging This application utilizes benzotriazole-based ultraviolet absorbers to protect the resin backbone from photodegradation. The fluorinated layer forms a dense shielding layer on the surface, reflecting and scattering some ultraviolet light; the Si-Ph bonds in the methylphenyl vinyl silicone resin itself possess photostability, and its conjugated structure can also absorb ultraviolet light and dissipate energy. Furthermore, modified mesoporous silica and barium strontium titanate / boron nitride core-shell particles scatter ultraviolet light, reducing the transmission depth of ultraviolet light in the coating and synergistically improving the resistance to photoaging.

[0027] The dendritic phosphorus-containing fluorosilicone resin added in this invention consists of three functional arms covalently linked on the same molecule: phosphate ester (flame retardant), perfluorohexylethyl (hydrophobic), and trimethoxysilane (interfacial bonding), preventing small molecule migration and precipitation, and ensuring long-term stability. The barium strontium titanate / boron nitride core-shell particles provide dielectric tunability and phase transition endotherm through the core, and dielectric isolation and anisotropic thermal conductivity through the shell. KH550 surface modification further enhances compatibility with the resin, forming a three-level synergistic effect of "core-shell-modification". Simultaneously, the flexible hydrophobic network of the fluorinated polyurethane prepolymer interpenetrates with the rigid heat-resistant network of the methylphenyl vinyl silicone resin, forming a matrix with toughness, adhesion, temperature resistance, and low surface energy. The coating prepared in this application significantly outperforms traditional conformal coatings in terms of high-frequency electrical properties, environmental resistance, and mechanical reliability. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: The preparation method of methylphenyl vinyl silicone resin includes the following steps: Under a nitrogen atmosphere, 28g of methyltrimethoxysilane, 35g of diphenyldimethoxysilane, 20g of methylphenyldimethoxysilane, 5g of vinyltrimethoxysilane, and 1g of trimethylmethoxysilane were dispersed in a reaction vessel and the temperature was controlled at 30℃. 150mL of water and 300mL of toluene were added to the reaction vessel, and hydrochloric acid was added to adjust the pH to 2. The temperature was controlled at 70℃ and the reaction was maintained for 6 hours. 0.01g of dibutyltin dilaurate was added, and the reaction was maintained for 2 hours. The organic layer was separated, and sodium bicarbonate was added to neutralize the organic layer to neutrality. The mixture was filtered, and toluene, water, and low-boiling substances were removed under vacuum of 0.08MPa and at 120℃. The mixture was then dried. The dried resin material was redissolved in toluene, and methyltrimethoxysilane (the mass ratio of resin material to methyltrimethoxysilane was 100:10) was added. The mixture was refluxed at 80℃ for 2 hours, and toluene and low-boiling substances were removed by vacuum distillation to obtain methylphenylvinylsilane resin.

[0030] The preparation method of HMDS-modified mesoporous silica includes the following steps: 2g of cetyltrimethylammonium bromide, 20mL of deionized water and 60mL of anhydrous ethanol were mixed together, and ammonia was added to adjust the pH to 9. The temperature was controlled at 30℃, and 10g of tetraethyl orthosilicate was added. The mixture was stirred and kept at the temperature for 3h, aged for 12h, dried at 80℃ for 12h, heated to 500℃ at a heating rate of 5℃ / min and calcined for 4h to obtain mesoporous silica. Under a nitrogen atmosphere, 10g of mesoporous silica and 80mL of toluene were mixed, and 2g of hexamethyldisilazane was added. The mixture was stirred and refluxed at 60℃ for 4h. After washing and drying, HMDS-modified mesoporous silica was obtained.

[0031] The preparation method of dendritic phosphorus-containing fluorosilicone resin includes the following steps: S1: 6g of ethylenediamine and 50mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 34.4g of methyl acrylate was added and the temperature was controlled at 25℃. The reaction was carried out under stirring for 24h. Excess methyl acrylate and methanol were removed by vacuum distillation to obtain the intermediate. The intermediate and 50mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 48g of ethylenediamine was added and the temperature was controlled at 25℃. The reaction was carried out under stirring for 48h. Excess ethylenediamine and methanol were removed by vacuum distillation to obtain PMMA-NH2. Under a nitrogen atmosphere, 10g PMMA-NH2, 100mL N,N-dimethylformamide, and 1.5g triethylamine were added to reactor A. The temperature was controlled at 0℃. 1.6g diethyl chlorophosphate was added, and the reaction was carried out at 40℃ with stirring for 12h. The triethylamine hydrochloride was removed by filtration. The filtrate was poured into deionized water (the volume ratio of deionized water to filtrate was 10:1) to precipitate. The precipitate was collected by centrifugation, washed, and dried to obtain phosphorylated PMMA. S2: Under a nitrogen atmosphere, 10g of phosphorylated PMMA and 150mL of N,N-dimethylformamide were added to reactor B, along with 2g of potassium carbonate and 6g of perfluorohexylethyl iodide. The reaction was carried out at 80℃ with stirring for 24h. The mixture was filtered, and the filtrate was poured into deionized water (deionized water: filtrate volume ratio of 10:1) to precipitate. The precipitate was then centrifuged and dried to obtain the intermediate product. S3: Under a nitrogen atmosphere, 10g of intermediate product, 150mL of N,N-dimethylformamide, and 2.2g of propyltrimethoxysilane isocyanate were added to reactor C. The reaction was carried out at 40℃ with stirring for 12h. N,N-dimethylformamide was removed by vacuum distillation. A mixed solution of toluene and n-hexane (toluene:n-hexane volume ratio of 1:2) was added to reprecipitate the product. The product was then dried to obtain dendritic phosphorus-containing fluorosilicone resin.

[0032] The preparation method of barium strontium titanate / boron nitride core-shell particles includes the following steps: A1: 3.4 g tetrabutyl titanate, 20 mL anhydrous ethanol, and 1 g acetylacetone were added to a reaction flask and dispersed. 1.66 g barium acetate, 0.54 g strontium acetate, and 40 mL anhydrous ethanol were mixed and added to the reaction flask. 2 mL glacial acetic acid and 1 mL deionized water were added, and the mixture was stirred at room temperature for 3 h to obtain a sol. The sol was transferred to an autoclave, heated to 160 °C at a rate of 2 °C / min, and held for 12 h. The mixture was then washed, dried (dried at 60 °C for 12 h), pulverized, and calcined (heated to 350 °C at a rate of 2 °C / min and held for 1 h, then heated to 650 °C at a rate of 5 °C / min and held for 3 h) to obtain barium strontium titanate powder. A2: Add 10g of barium strontium titanate powder and 80mL of anhydrous ethanol to a reaction flask, add ammonia to adjust the pH to 9, add 5g of tetraethyl orthosilicate, 5mL of deionized water and 20mL of anhydrous ethanol to the reaction flask, control the temperature at 40℃, keep warm and stir for 5h, centrifuge, wash and dry to obtain barium strontium titanate powder coated with silica; A3: A mixture of 2.5g boric acid, 7.5g urea, 100mL anhydrous ethanol, and 5mL water was added to a reaction flask and dispersed. 5g of barium strontium titanate powder coated with silica was added and dispersed. The mixture was stirred at room temperature for 12 hours. Anhydrous ethanol and water were removed by rotary evaporation. The mixture was dried (drying at 60℃ for 12 hours and treating in nitrogen at 150℃ for 2 hours), calcined (heating to 300℃ at a rate of 5℃ / min in an argon atmosphere at a flow rate of 100mL / min; heating to 850℃ at a rate of 10℃ / min in a 4:1 argon:ammonia mixture at a flow rate of 120mL / min and holding at 850℃ for 3 hours; cooling to 600℃ at a rate of 2℃ / min in an argon atmosphere at a flow rate of 100mL / min; cooling to room temperature at a rate of 10℃ / min), etched with 3wt% hydrofluoric acid for 30 minutes, washed with water, and dried to obtain BST@BN core-shell particles. A4: Mix 0.25g KH550, 50mL ethanol, and 1mL water, add 5g BST@BN particles for dispersion, control the temperature at 60℃, stir and reflux for 2h, centrifuge, wash with ethanol, and dry to obtain barium strontium titanate / boron nitride core-shell particles.

[0033] The preparation method of hydroxyl-terminated fluorinated polyurethane prepolymer includes the following steps: B1: 10g of isophorone diisocyanate, 0.015g of dibutyltin dilaurate, and 5mL of acetone were added to a reaction flask and dispersed. The temperature was controlled at 40℃. 7.8g of hexafluorobutanol was added dropwise, and the reaction was maintained at this temperature for 2h. The temperature was controlled at 0℃, and 4.7g of diethanolamine was added dropwise. The reaction was carried out for 1h. The acetone was removed by vacuum distillation to obtain a fluorinated diol with terminal hydroxyl groups. B2: 50g of polytetrahydrofuran ether diol (PTMG, Mn=1000) and 8g of hydroxyl-terminated fluorinated diol were added to a reaction flask and dispersed. The temperature was controlled at 70℃. 15g of isophorone diisocyanate and 0.01g of dibutyltin dilaurate were added. The temperature was controlled at 70℃ and the reaction was maintained for 2 hours. The temperature was then controlled at 50℃. 1g of 1,4-butanediol and 80g of propylene glycol methyl ether acetate were mixed and added to the reaction flask. The temperature was controlled at 70℃ and the reaction was maintained for 1.5 hours to obtain a hydroxyl-terminated fluorinated polyurethane prepolymer.

[0034] Example 2: The preparation method of methylphenyl vinyl silicone resin includes the following steps: Under a nitrogen atmosphere, 31g of methyltrimethoxysilane, 38g of diphenyldimethoxysilane, 22g of methylphenyldimethoxysilane, 7g of vinyltrimethoxysilane, and 3g of trimethylmethoxysilane were dispersed in a reaction vessel and the temperature was controlled at 40℃. 200mL of water and 400mL of toluene were added to the reaction vessel, and hydrochloric acid was added to adjust the pH to 2. The temperature was controlled at 70℃ and the reaction was maintained for 9 hours. 0.03g of dibutyltin dilaurate was added, and the reaction was maintained for 3 hours. The organic layer was separated, and sodium bicarbonate was added to neutralize the organic layer to neutrality. The mixture was filtered, and toluene, water, and low-boiling substances were removed under a vacuum of 0.09MPa and at 130℃. The mixture was then dried. The dried resin material was redissolved in toluene, and methyltrimethoxysilane (the mass ratio of resin material to methyltrimethoxysilane was 100:10) was added. The mixture was refluxed at 90℃ for 3 hours, and toluene and low-boiling substances were removed by vacuum distillation to obtain methylphenylvinylsilane resin.

[0035] The preparation method of HMDS-modified mesoporous silica includes the following steps: 3.5 g of cetyltrimethylammonium bromide, 30 mL of deionized water, and 80 mL of anhydrous ethanol were mixed together. Ammonia was added to adjust the pH to 9, and the temperature was controlled at 40 °C. 15 g of tetraethyl orthosilicate was added, and the mixture was stirred and kept at the temperature for 4.5 h. The mixture was then allowed to stand for 18 h to age, dried at 80-100 °C for 18 h, heated to 550 °C at a heating rate of 5 °C / min, and calcined for 5 h to obtain mesoporous silica. Under a nitrogen atmosphere, 10g of mesoporous silica and 120mL of toluene were mixed, and 3.5g of hexamethyldisilazane was added. The mixture was stirred and refluxed at 75℃ for 8 hours. After washing and drying, HMDS-modified mesoporous silica was obtained.

[0036] The preparation method of dendritic phosphorus-containing fluorosilicone resin includes the following steps: S1: 6g of ethylenediamine and 70mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 36g of methyl acrylate was added and the temperature was controlled at 30℃. The reaction was carried out under stirring for 36h. Excess methyl acrylate and methanol were removed by vacuum distillation to obtain the intermediate. The intermediate and 70mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 55g of ethylenediamine was added and the temperature was controlled at 30℃. The reaction was carried out under stirring for 58h. Excess ethylenediamine and methanol were removed by vacuum distillation to obtain PMMA-NH2. Under a nitrogen atmosphere, 10g PMMA-NH2, 150mL N,N-dimethylformamide, and 2g triethylamine were added to reactor A. The temperature was controlled at 0℃. 2.2g diethyl chlorophosphate was added, and the reaction was carried out at 50℃ with stirring for 16h. The triethylamine hydrochloride was removed by filtration. The filtrate was poured into deionized water (the volume ratio of deionized water to filtrate was 10:1) to precipitate. The precipitate was collected by centrifugation, washed, and dried to obtain phosphorylated PMMA. S2: Under a nitrogen atmosphere, 10g of phosphorylated PMMA and 200mL of N,N-dimethylformamide were added to reactor B, along with 2.5g of potassium carbonate and 7.5g of perfluorohexylethyl iodide. The reaction was carried out at 90℃ with stirring for 36h. The mixture was filtered, and the filtrate was poured into deionized water (deionized water: filtrate volume ratio of 10:1) to precipitate. The precipitate was then centrifuged and dried to obtain the intermediate product. S3: Under a nitrogen atmosphere, 10g of intermediate product, 200mL of N,N-dimethylformamide, and 3g of propyltrimethoxysilane isocyanate were added to reactor C. The reaction was carried out at 50℃ with stirring for 18h. N,N-dimethylformamide was removed by vacuum distillation. A mixed solution of toluene and n-hexane (toluene:n-hexane volume ratio of 1:2) was added for reprecipitation. The mixture was dried to obtain dendritic phosphorus-containing fluorosilicone resin.

[0037] The preparation method of barium strontium titanate / boron nitride core-shell particles includes the following steps: A1: 3.4 g tetrabutyl titanate, 30 mL anhydrous ethanol, and 1.5 g acetylacetone were dispersed in a reaction flask; 1.8 g barium acetate, 0.6 g strontium acetate, and 50 mL anhydrous ethanol were mixed and added to the reaction flask; 2.5 mL glacial acetic acid and 2 mL deionized water were added, and the mixture was stirred at room temperature for 4.5 h to obtain a sol; the sol was transferred to an autoclave, heated to 160 °C at a rate of 2 °C / min, and held for 16 h; the mixture was washed, dried (dried at 70 °C for 16 h), pulverized, and calcined (heated to 350 °C at a rate of 2 °C / min and held for 1 h, then heated to 650 °C at a rate of 5 °C / min and held for 3 h) to obtain barium strontium titanate powder; A2: Add 10g of barium strontium titanate powder and 120mL of anhydrous ethanol to a reaction flask, add ammonia to adjust the pH to 9, add 8g of tetraethyl orthosilicate, 8mL of deionized water and 30mL of anhydrous ethanol to the reaction flask, control the temperature at 50℃, keep warm and stir for 7h, centrifuge, wash and dry to obtain barium strontium titanate powder coated with silica; A3: A mixture of 4g boric acid, 10g urea, 150mL anhydrous ethanol, and 7mL water was added to a reaction flask and dispersed. 5g of barium strontium titanate powder coated with silica was added and dispersed. The mixture was stirred at room temperature for 16 hours. Anhydrous ethanol and water were removed by rotary evaporation. The mixture was dried (drying at 60℃ for 12 hours and treating in nitrogen at 150℃ for 2 hours), calcined (in an argon atmosphere at a flow rate of 100mL / min, heating at a rate of 5℃ / min to 300℃; in a mixture of argon and ammonia with a volume ratio of 4:1 at a flow rate of 120mL / min, heating at a rate of 10℃ / min to 850℃ and holding for 3 hours; in an argon atmosphere at a flow rate of 100mL / min, cooling at a rate of 2℃ / min to 600℃; cooling at a rate of 10℃ / min to room temperature), etched with 3wt% hydrofluoric acid for 30 minutes, washed with water, and dried to obtain BST@BN core-shell particles. A4: Mix 0.4g KH550, 80mL ethanol, and 2mL water, add 5g BST@BN particles for dispersion, control the temperature at 70℃, stir and reflux for 3h, centrifuge, wash with ethanol, and dry to obtain barium strontium titanate / boron nitride core-shell particles.

[0038] The preparation method of hydroxyl-terminated fluorinated polyurethane prepolymer includes the following steps: B1: 10g of isophorone diisocyanate, 0.02g of dibutyltin dilaurate, and 7mL of acetone were added to a reaction flask and dispersed. The temperature was controlled at 50℃. 8.2g of hexafluorobutanol was added dropwise, and the reaction was maintained at this temperature for 3h. The temperature was controlled at 0℃, and 5g of diethanolamine was added dropwise. The reaction was carried out for 2h. The acetone was removed by vacuum distillation to obtain a fluorinated diol with terminal hydroxyl groups. B2: 60g of polytetrahydrofuran ether diol (PTMG, Mn=1000) and 12g of hydroxyl-terminated fluorinated diol were added to a reaction flask and dispersed. The temperature was controlled at 80℃. 20g of isophorone diisocyanate and 0.03g of dibutyltin dilaurate were added. The temperature was controlled at 80℃ and the reaction was maintained for 3 hours. The temperature was then controlled at 55℃. 2g of 1,4-butanediol and 100g of propylene glycol methyl ether acetate were mixed and added to the reaction flask. The temperature was controlled at 75℃ and the reaction was maintained for 2 hours to obtain a hydroxyl-terminated fluorinated polyurethane prepolymer.

[0039] Example 3: The preparation method of methylphenyl vinyl silicone resin includes the following steps: Under a nitrogen atmosphere, 35g of methyltrimethoxysilane, 40g of diphenyldimethoxysilane, 25g of methylphenyldimethoxysilane, 10g of vinyltrimethoxysilane, and 5g of trimethylmethoxysilane were dispersed in a reaction vessel and the temperature was controlled at 45℃. 300mL of water and 600mL of toluene were added to the reaction vessel, and hydrochloric acid was added to adjust the pH to 3. The temperature was controlled at 75℃ and the reaction was maintained for 9 hours. 0.05g of dibutyltin dilaurate was added, and the reaction was maintained for 4 hours. The organic layer was separated, and sodium bicarbonate was added to neutralize the organic layer to neutrality. The mixture was filtered, and toluene, water, and low-boiling substances were removed under vacuum of 0.1MPa and at 150℃. The mixture was then dried. The dried resin material was redissolved in toluene, and methyltrimethoxysilane (the mass ratio of resin material to methyltrimethoxysilane was 100:10) was added. The mixture was refluxed at 100℃ for 4 hours, and toluene and low-boiling substances were removed by vacuum distillation to obtain methylphenylvinylsilane resin.

[0040] The preparation method of HMDS-modified mesoporous silica includes the following steps: 5g of cetyltrimethylammonium bromide, 40mL of deionized water and 100mL of anhydrous ethanol were mixed together, and ammonia was added to adjust the pH to 10. The temperature was controlled at 30-50℃, and 20g of tetraethyl orthosilicate was added. The mixture was stirred and kept at the temperature for 6h, aged for 24h, dried at 100℃ for 24h, heated to 600℃ at a heating rate of 5℃ / min and calcined for 6h to obtain mesoporous silica. Under a nitrogen atmosphere, 10g of mesoporous silica and 150mL of toluene were mixed, and 5g of hexamethyldisilazane was added. The mixture was stirred and refluxed at 90℃ for 12h. After washing and drying, HMDS-modified mesoporous silica was obtained.

[0041] The preparation method of dendritic phosphorus-containing fluorosilicone resin includes the following steps: S1: 6g of ethylenediamine and 100mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 5℃. 38.7g of methyl acrylate was added and the temperature was controlled at 35℃. The reaction was carried out under stirring for 48h. Excess methyl acrylate and methanol were removed by vacuum distillation to obtain the intermediate. The intermediate and 100mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 5℃. 60g of ethylenediamine was added and the temperature was controlled at 35℃. The reaction was carried out under stirring for 72h. Excess ethylenediamine and methanol were removed by vacuum distillation to obtain PMMA-NH2. Under a nitrogen atmosphere, 10g PMMA-NH2, 200mL N,N-dimethylformamide, and 2.4g triethylamine were added to reactor A. The temperature was controlled at 5℃. 2.7g diethyl chlorophosphate was added, and the reaction was carried out at 60℃ with stirring for 24h. The triethylamine hydrochloride was removed by filtration. The filtrate was poured into deionized water (the volume ratio of deionized water to filtrate was 10:1) to precipitate. The precipitate was collected by centrifugation, washed, and dried to obtain phosphorylated PMMA. S2: Under a nitrogen atmosphere, 10g of phosphorylated PMMA and 200mL of N,N-dimethylformamide were added to reactor B, along with 3g of potassium carbonate and 9g of perfluorohexylethyl iodide. The reaction was carried out at 100℃ with stirring for 48h. The mixture was filtered, and the filtrate was poured into deionized water (deionized water: filtrate volume ratio of 10:1) to precipitate. The precipitate was then centrifuged and dried to obtain the intermediate product. S3: Under a nitrogen atmosphere, 10g of intermediate product, 200mL of N,N-dimethylformamide, and 3.7g of propyltrimethoxysilane isocyanate were added to reactor C. The reaction was carried out at 60℃ with stirring for 24h. N,N-dimethylformamide was removed by vacuum distillation. A mixed solution of toluene and n-hexane (toluene:n-hexane volume ratio of 1:2) was added to reprecipitate the product. The product was then dried to obtain dendritic phosphorus-containing fluorosilicone resin.

[0042] The preparation method of barium strontium titanate / boron nitride core-shell particles includes the following steps: A1: 3.4 g tetrabutyl titanate, 30 mL anhydrous ethanol, and 2 g acetylacetone were added to a reaction flask and dispersed. 1.92 g barium acetate, 0.75 g strontium acetate, and 60 mL anhydrous ethanol were mixed and added to the reaction flask. 3 mL glacial acetic acid and 2 mL deionized water were added, and the mixture was stirred at room temperature for 6 h to obtain a sol. The sol was transferred to an autoclave, heated to 160 °C at a rate of 2 °C / min, and held for 24 h. The mixture was then washed, dried (dried at 80 °C for 24 h), pulverized, and calcined (heated to 350 °C at a rate of 2 °C / min and held for 1 h, then heated to 650 °C at a rate of 5 °C / min and held for 3 h) to obtain barium strontium titanate powder. A2: Add 10g of barium strontium titanate powder and 160mL of anhydrous ethanol to a reaction flask, add ammonia to adjust the pH to 10, add 10g of tetraethyl orthosilicate, 10mL of deionized water and 40mL of anhydrous ethanol to the reaction flask, control the temperature at 60℃, keep warm and stir for 10h, centrifuge, wash and dry to obtain barium strontium titanate powder coated with silica; A3: A mixture of 5g boric acid, 12.5g urea, 200mL anhydrous ethanol, and 10mL water was added to a reaction flask and dispersed. 5g of barium strontium titanate powder coated with silica was added and dispersed. The mixture was stirred at room temperature for 24 hours. Anhydrous ethanol and water were removed by rotary evaporation. The mixture was dried (drying at 60℃ for 12 hours and treating in nitrogen at 150℃ for 2 hours), calcined (in an argon atmosphere at a flow rate of 100mL / min, heating at a rate of 5℃ / min to 300℃; in a mixture of argon and ammonia with a volume ratio of 4:1 at a flow rate of 120mL / min, heating at a rate of 10℃ / min to 850℃ and holding for 3 hours; in an argon atmosphere at a flow rate of 100mL / min, cooling at a rate of 2℃ / min to 600℃; cooling at a rate of 10℃ / min to room temperature), etched with 3wt% hydrofluoric acid for 30 minutes, washed with water, and dried to obtain BST@BN core-shell particles. A4: Mix 0.50g KH550, 100mL ethanol, and 2mL water, add 5g BST@BN particles for dispersion, control the temperature at 80℃, stir and reflux for 4h, centrifuge, wash with ethanol, and dry to obtain barium strontium titanate / boron nitride core-shell particles.

[0043] The preparation method of hydroxyl-terminated fluorinated polyurethane prepolymer includes the following steps: B1: 10g of isophorone diisocyanate, 0.03g of dibutyltin dilaurate, and 5-10mL of acetone were added to a reaction flask and dispersed. The temperature was controlled at 60℃. 8.6g of hexafluorobutanol was added dropwise, and the reaction was maintained at this temperature for 4h. The temperature was controlled at 5℃, and 5.2g of diethanolamine was added dropwise. The reaction was maintained for 3h. The acetone was removed by vacuum distillation to obtain a fluorinated diol with terminal hydroxyl groups. B2: 70g of polytetrahydrofuran ether diol (PTMG, Mn=1000) and 15g of hydroxyl-terminated fluorinated diol were added to a reaction flask and dispersed. The temperature was controlled at 90℃. 25g of isophorone diisocyanate and 0.05g of dibutyltin dilaurate were added. The temperature was controlled at 90℃ and the reaction was maintained for 4 hours. The temperature was then controlled at 60℃. 3g of 1,4-butanediol and 120g of propylene glycol methyl ether acetate were mixed and added to the reaction flask. The temperature was controlled at 80℃ and the reaction was maintained for 3 hours to obtain a hydroxyl-terminated fluorinated polyurethane prepolymer.

[0044] Example 4: A method for preparing a composite nano-protective coating resistant to environmental aging, comprising the following steps: 40 parts by weight of the hydroxyl-terminated fluorinated polyurethane prepolymer prepared in Example 1, 15 parts by weight of the methylphenyl vinyl silicone resin prepared in Example 1, 18 parts by weight of propylene glycol methyl ether acetate, and 7 parts by weight of propylene glycol methyl ether are blended together; 8 parts by weight of the HMDS-modified mesoporous silica prepared in Example 1, 0.5 parts by weight of UV329, and 3 parts by weight of the dendritic phosphorus-containing fluorosilicone resin prepared in Example 1 are blended together; 8 parts by weight of the strontium barium titanate / boron nitride core-shell particles prepared in Example 1 are blended together; and 13 parts by weight of the HDI trimer curing agent are added and blended together to obtain the composite nano-protective coating.

[0045] Example 5: A method for preparing a composite nano-protective coating resistant to environmental aging, comprising the following steps: 40 parts by weight of the hydroxyl-terminated fluorinated polyurethane prepolymer prepared in Example 2, 15 parts by weight of the methylphenyl vinyl silicone resin prepared in Example 2, 18 parts by weight of propylene glycol methyl ether acetate, and 7 parts by weight of propylene glycol methyl ether are blended together; 8 parts by weight of the HMDS-modified mesoporous silica prepared in Example 2, 0.5 parts by weight of UV329, and 3 parts by weight of the dendritic phosphorus-containing fluorosilicone resin prepared in Example 2 are blended together; 8 parts by weight of the strontium barium titanate / boron nitride core-shell particles prepared in Example 2 are blended together; and 13 parts by weight of the HDI trimer curing agent are added and blended together to obtain the composite nano-protective coating.

[0046] Example 6: A method for preparing a composite nano-protective coating resistant to environmental aging, comprising the following steps: 40 parts by weight of the hydroxyl-terminated fluorinated polyurethane prepolymer prepared in Example 3, 15 parts by weight of the methylphenyl vinyl silicone resin prepared in Example 3, 18 parts by weight of propylene glycol methyl ether acetate, and 7 parts by weight of propylene glycol methyl ether are blended together; 8 parts by weight of the HMDS-modified mesoporous silica prepared in Example 3, 0.5 parts by weight of UV329, and 3 parts by weight of the dendritic phosphorus-containing fluorosilicone resin prepared in Example 3 are blended together; 8 parts by weight of the strontium barium titanate / boron nitride core-shell particles prepared in Example 3 are blended together; and 13 parts by weight of the HDI trimer curing agent are added and blended together to obtain the composite nano-protective coating.

[0047] Comparative Example 1: The preparation method of HMDS modified silica includes the following steps: Under a nitrogen atmosphere, 10g of nano silica and 120mL of toluene are mixed, 3.5g of hexamethyldisilazane is added, the temperature is controlled at 75℃, and the mixture is stirred and refluxed for 8h. After washing and drying, HMDS modified silica is obtained.

[0048] Comparative Example 2: The preparation method of dendritic fluorosilicone resin includes the following steps: S1: 6g of ethylenediamine and 70mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 36g of methyl acrylate was added and the temperature was controlled at 30℃. The reaction was carried out under stirring for 36h. Excess methyl acrylate and methanol were removed by vacuum distillation to obtain the intermediate. The intermediate and 70mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 55g of ethylenediamine was added and the temperature was controlled at 30℃. The reaction was carried out under stirring for 58h. Excess ethylenediamine and methanol were removed by vacuum distillation to obtain PMMA-NH2. S2: Under a nitrogen atmosphere, 10g PMMA-NH2 and 200mL N,N-dimethylformamide were added to reactor B, along with 2.5g potassium carbonate and 7.5g perfluorohexylethyl iodide. The reaction was carried out at 90℃ with stirring for 36h. The mixture was filtered, and the filtrate was poured into deionized water (deionized water: filtrate volume ratio of 10:1) to precipitate. The precipitate was then centrifuged and dried to obtain the intermediate product. S3: Under a nitrogen atmosphere, 10g of intermediate product, 200mL of N,N-dimethylformamide, and 3g of propyltrimethoxysilane isocyanate were added to reactor C. The reaction was carried out at 50℃ with stirring for 18h. N,N-dimethylformamide was removed by vacuum distillation. A mixed solution of toluene and n-hexane (toluene:n-hexane volume ratio of 1:2) was added for reprecipitation. The mixture was dried to obtain dendritic fluorosilicone resin.

[0049] Comparative Example 3: The preparation method of dendritic phosphorus-containing silicone resin includes the following steps: S1: 6g of ethylenediamine and 70mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 36g of methyl acrylate was added and the temperature was controlled at 30℃. The reaction was carried out under stirring for 36h. Excess methyl acrylate and methanol were removed by vacuum distillation to obtain the intermediate. The intermediate and 70mL of methanol were added to a reaction flask and dispersed. The temperature was controlled at 0℃. 55g of ethylenediamine was added and the temperature was controlled at 30℃. The reaction was carried out under stirring for 58h. Excess ethylenediamine and methanol were removed by vacuum distillation to obtain PMMA-NH2. Under a nitrogen atmosphere, 10g PMMA-NH2, 150mL N,N-dimethylformamide, and 2g triethylamine were added to reactor A. The temperature was controlled at 0℃. 2.2g diethyl chlorophosphate was added, and the reaction was carried out at 50℃ with stirring for 16h. The triethylamine hydrochloride was removed by filtration. The filtrate was poured into deionized water (the volume ratio of deionized water to filtrate was 10:1) to precipitate. The precipitate was collected by centrifugation, washed, and dried to obtain phosphorylated PMMA. S2: Under a nitrogen atmosphere, 10g of intermediate product, 200mL of N,N-dimethylformamide, and 3g of propyltrimethoxysilane isocyanate were added to reactor C. The reaction was carried out at 50℃ with stirring for 18h. N,N-dimethylformamide was removed by vacuum distillation. A mixed solution of toluene and n-hexane (toluene:n-hexane volume ratio of 1:2) was added to reprecipitate the product. The product was then dried to obtain dendritic phosphorus-containing silicone resin.

[0050] Comparative Example 4: The preparation method of barium strontium titanate / boron nitride core-shell particles includes the following steps: A1: 3.4 g tetrabutyl titanate, 30 mL anhydrous ethanol, and 1.5 g acetylacetone were dispersed in a reaction flask; 1.8 g barium acetate, 0.6 g strontium acetate, and 50 mL anhydrous ethanol were mixed and added to the reaction flask; 2.5 mL glacial acetic acid and 2 mL deionized water were added, and the mixture was stirred at room temperature for 4.5 h to obtain a sol; the sol was transferred to an autoclave, heated to 160 °C at a rate of 2 °C / min, and held for 16 h; the mixture was washed, dried (dried at 70 °C for 16 h), pulverized, and calcined (heated to 350 °C at a rate of 2 °C / min and held for 1 h, then heated to 650 °C at a rate of 5 °C / min and held for 3 h) to obtain barium strontium titanate powder; A2: A mixture of 4g boric acid, 10g urea, 150mL anhydrous ethanol, and 7mL water was added to a reaction flask and dispersed. 5g barium strontium titanate powder was added and dispersed. The mixture was stirred at room temperature for 16 hours. Anhydrous ethanol and water were removed by rotary evaporation. The mixture was dried (drying at 60℃ for 12 hours and treating in nitrogen at 150℃ for 2 hours), calcined (heating to 300℃ at a rate of 5℃ / min in an argon atmosphere at a flow rate of 100mL / min; heating to 850℃ at a rate of 10℃ / min in a 4:1 argon:ammonia mixture at a flow rate of 120mL / min and holding at 850℃ for 3 hours; cooling to 600℃ at a rate of 2℃ / min in an argon atmosphere at a flow rate of 100mL / min; cooling to room temperature at a rate of 10℃ / min), etched with 3wt% hydrofluoric acid for 30 minutes, washed with water, and dried to obtain BST@BN core-shell particles. A3: Mix 0.4g KH550, 80mL ethanol, and 2mL water, add 5g BST@BN particles for dispersion, control the temperature at 70℃, stir and reflux for 3h, centrifuge, wash with ethanol, and dry to obtain barium strontium titanate / boron nitride core-shell particles.

[0051] Comparative Example 5: The preparation method of barium strontium titanate / boron nitride composite particles includes the following steps: A1: 3.4 g tetrabutyl titanate, 30 mL anhydrous ethanol, and 1.5 g acetylacetone were dispersed in a reaction flask; 1.8 g barium acetate, 0.6 g strontium acetate, and 50 mL anhydrous ethanol were mixed and added to the reaction flask; 2.5 mL glacial acetic acid and 2 mL deionized water were added, and the mixture was stirred at room temperature for 4.5 h to obtain a sol; the sol was transferred to an autoclave, heated to 160 °C at a rate of 2 °C / min, and held for 16 h; the mixture was washed, dried (dried at 70 °C for 16 h), pulverized, and calcined (heated to 350 °C at a rate of 2 °C / min and held for 1 h, then heated to 650 °C at a rate of 5 °C / min and held for 3 h) to obtain barium strontium titanate powder; A2: A mixture of 4g boric acid, 10g urea, 150mL anhydrous ethanol, and 7mL water was added to a reaction flask and dispersed. The mixture was stirred at room temperature for 16 hours. Anhydrous ethanol and water were removed by rotary evaporation. The mixture was dried (drying at 60℃ for 12 hours and treating in nitrogen at 150℃ for 2 hours), calcined (heating to 300℃ at a rate of 5℃ / min in an argon atmosphere at a flow rate of 100mL / min; heating to 850℃ at a rate of 10℃ / min in a 4:1 argon:ammonia mixture at a flow rate of 120mL / min and holding at 850℃ for 3 hours; cooling to 600℃ at a rate of 2℃ / min in an argon atmosphere at a flow rate of 100mL / min; cooling to room temperature at a rate of 10℃ / min), etched with 3wt% hydrofluoric acid for 30 minutes, washed with water, and dried to obtain BN particles. The BN particles were then mixed with 5g barium strontium titanate powder to obtain composite particles. A3: Mix 0.4g KH550, 80mL ethanol, and 2mL water, add 5g of composite particles for dispersion, control the temperature at 70℃, stir and reflux for 3h, centrifuge, wash with ethanol, and dry to obtain barium strontium titanate / boron nitride composite particles.

[0052] Comparative Example 6 is the same as Example 5 except that the HMDS-modified silica added in Example 5 is replaced with an equal amount of HMDS-modified silica prepared in Comparative Example 1. The other components and preparation methods are completely the same as in Example 5.

[0053] Compared with Example 5, Comparative Example 7 only replaced the dendritic phosphorus-containing fluorosilicone resin added in Example 5 with the dendritic fluorosilicone resin prepared in Comparative Example 2 in an equal amount. The remaining components and preparation methods were completely the same as those in Example 5.

[0054] Compared with Example 5, Comparative Example 8 only replaced the dendritic phosphorus-containing fluorosilicone resin added in Example 5 with an equal amount of the dendritic phosphorus-containing fluorosilicone resin prepared in Comparative Example 3. The remaining components and preparation methods were completely the same as in Example 5.

[0055] Comparative Example 9 differs from Example 5 only in that the barium strontium titanate / boron nitride core-shell particles added in Example 5 are replaced in equal amounts with the barium strontium titanate / boron nitride core-shell particles prepared in Comparative Example 4. The remaining components and preparation methods are completely consistent with those of Example 5.

[0056] Comparative Example 10 differs from Example 5 only in that the barium strontium titanate / boron nitride core-shell particles added in Example 5 are replaced in equal amounts with the barium strontium titanate / boron nitride composite particles prepared in Comparative Example 5. The remaining components and preparation methods are completely consistent with those of Example 5.

[0057] Performance testing (1) High frequency and low dielectric loss Dielectric constant and dielectric loss: The coatings prepared in Examples 4-6 and Comparative Examples 6-10 were coated onto glass plates according to IPC-TM-650 2.5.5.9. The dielectric constant and dielectric loss were tested in the 100MHz frequency range using the parallel plate capacitance method. The test environment was 25℃ and 50% RH. The test results are shown in Table 1. Volume resistivity: Tested according to GB / T 1410-2019 "Test methods for volume resistivity and surface resistivity of solid insulating materials", and the test results are shown in Table 1; Table 1: Statistical Table of High Frequency Low Dielectric Loss Detection Data

[0058] As shown in Table 1, the coatings prepared by the coatings in Examples 4-6 of this application have low dielectric loss, dielectric constant, and high insulation performance under high frequency environment; in Comparative Example 6, the hydrophilic silanol groups on the surface of the unmodified SiO2 cause interfacial polarization, resulting in a significant increase in dielectric loss; in Comparative Example 7 (phosphorus-free), the flame retardancy and dielectric properties are slightly reduced; in Comparative Example 8 (fluorine-free), the surface energy and polarity of the coating are increased, and the dielectric constant and loss are significantly increased; in Comparative Example 9, the high-temperature sintering and agglomeration of barium strontium titanate destroys the nano-effect, and the discontinuity of the boron nitride shell leads to an increase in leakage conduction; in Comparative Example 10, the simple blending of barium strontium titanate and boron nitride cannot achieve core-shell isolation, resulting in serious leakage conduction.

[0059] (2) Superhydrophobic and tri-proof properties Water contact angle: Deionized water (5 μL droplet volume) was dropped onto the coating surface using a contact angle meter, and the static contact angle was measured. The test results are shown in Table 2. According to GB / T 1740-2007 "Test Method for Damp Heat Resistance of Coating Film", the test was conducted for 10 cycles in the high temperature and high humidity stage (60℃, RH95%) and the low temperature and high humidity stage (30℃, RH95%). The test results are shown in Table 2. According to GB / T 1741-2020 "Determination of Antifungal Resistance of Paint Films", the fungal species were Aspergillus niger, Aspergillus flavus, Aspergillus versicolor, Penicillium cordiformis, and Chaetomium globosum. The temperature was 24-31℃, the relative humidity was 90-100%, and the test was conducted for 28 days. The test results are shown in Table 2. The test was conducted according to GB / T 1771-2007 "Determination of resistance to neutral salt spray of paints and varnishes", using 5% salt solution, pH 7, salt spray deposition rate of 1 mL / 80 cm·2h, test temperature of 35℃, and test results for 200h. The results are shown in Table 2. Table 2: Statistical Table of Superhydrophobicity and Waterproofing Performance Test Data

[0060] As shown in Table 2, the coatings prepared by the coatings in Examples 4-6 of this application exhibit superhydrophobicity and excellent three-proof properties. The three-proof properties of Comparative Examples 6, 7, and 9 basically meet the requirements, but all indicators are lower than those of Examples 4-6. Comparative Example 8 lacks a fluorinated hydrophobic layer, and the coating shows significant failure in both damp heat and salt spray tests. Comparative Example 10 also shows a significant decrease in three-proof properties due to poor filler dispersion and numerous interface defects.

[0061] (3) Thermal shock resistance Temperature shock resistance: According to GB / T 2423.22-2012 "Environmental testing - Part 2: Test methods. Test N: Temperature change", the test was carried out at low temperature -75℃ and high temperature 300℃. The test results are shown in Table 3. Instantaneous heat resistance: According to GB / T 1735-2009 "Determination of heat resistance of paints and varnishes", the test panels coated with paint were placed in an oven at 260℃ for 30 minutes. After removal, the coating was tested for blistering, cracking, discoloration or peeling. The test results are shown in Table 3. Table 3: Statistical Table of Thermal Shock Resistance Test Data

[0062] As shown in Table 3, the coatings prepared by the coatings in Examples 4-6 of this application have good temperature resistance. Comparative Example 8, due to the lack of fluorinated polyurethane flexible segments, has insufficient IPN network toughness, high low-temperature brittleness, and a significant decrease in the number of thermal shock cycles. In Comparative Example 9, barium strontium titanate is prone to agglomeration, resulting in uneven filler dispersion, mismatch in local thermal expansion coefficients of the coating, and decreased thermal shock resistance. In Comparative Example 10, boron nitride and barium strontium titanate do not form a core-shell structure, the phonon heat transfer path is discontinuous, the thermal conductivity is the lowest, local hot spots are difficult to diffuse effectively, and the thermal shock resistance is the worst.

[0063] (4) Flame retardant and adhesion properties Flame retardancy rating: Tested using the vertical burning test method; the test results are shown in Table 4. Adhesion: According to GB / T 9286-2021 "Paints and Varnishes Cross-cut Test"; after aging in a humid and hot environment of 85℃ and 85% relative humidity for 1000h, the adhesion of the coating was tested again. The test results are shown in Table 4. Table 4: Statistical Table of Flame Retardant and Adhesion Performance Test Data

[0064] As shown in Table 4, the coatings prepared by the coatings in Examples 4-6 of this application have good flame retardancy and high adhesion between the coating and the substrate. In Comparative Example 7, the phosphate ester arm is missing, which weakens the interfacial anchoring ability of the dendritic molecules; in Comparative Example 8, although the trimethoxysilane anchor point exists, it is more prone to hydrolysis under humid and hot conditions due to the lack of fluorine-containing layer protection; in Comparative Example 10, barium strontium titanate and boron nitride failed to form a core-shell isolation structure, resulting in poor compatibility between the filler and the substrate interface and the worst resistance to humid and hot conditions.

[0065] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing a composite nano-protective coating resistant to environmental aging, characterized in that, Includes the following steps: A composite nano-protective coating is obtained by blending hydroxyl-terminated fluorinated polyurethane prepolymer, methylphenyl vinyl silicone resin, and solvent, adding HMDS-modified mesoporous silica, ultraviolet absorber, and dendritic phosphorus-containing fluorosilicone resin, adding barium strontium titanate / boron nitride core-shell particles, and adding HDI trimer curing agent. The dendritic phosphorus-containing fluorosilicone resin is prepared by esterification of PMMA-NH2 with diethyl chlorophosphate, quaternization of perfluorohexyl ethyl iodide to introduce a perfluorinated chain, and silane coupling reaction of propyltrimethoxysilane.

2. The method for preparing the environmentally resistant composite nano-protective coating according to claim 1, characterized in that, The preparation method of the dendritic phosphorus-containing fluorosilicone resin includes the following steps: S1: Under a nitrogen atmosphere, PMMA-NH2, N,N-dimethylformamide, and triethylamine are added to reactor A. The temperature is controlled at 0-5℃. Diethyl chlorophosphate is added. The temperature is controlled at 40-60℃. The reaction is carried out under stirring for 12-24 hours. The mixture is filtered, and the filtrate is poured into deionized water to precipitate. The precipitate is collected by centrifugation, washed, and dried to obtain phosphorylated PMMA. S2: Under a nitrogen atmosphere, phosphated PMMA and N,N-dimethylformamide were added to reactor B, along with potassium carbonate and perfluorohexylethyl iodide. The reaction was carried out at a temperature of 80-100℃ with stirring for 24-48 hours. The mixture was filtered, and the filtrate was poured into deionized water to precipitate. The precipitate was then centrifuged and dried to obtain the intermediate product. S3: Under a nitrogen atmosphere, the intermediate product, N,N-dimethylformamide, and propyltrimethoxysilane isocyanate are added to reactor C. The temperature is controlled at 40-60℃ and the reaction is maintained at this temperature for 12-24 hours with stirring. The N,N-dimethylformamide is removed by vacuum distillation, the precipitate is reprecipitated, and the product is dried to obtain dendritic phosphorus-containing fluorosilicone resin.

3. The method for preparing the environmentally resistant composite nano-protective coating according to claim 2, characterized in that, The addition ratio of PMMA-NH2, N,N-dimethylformamide, triethylamine, and diethyl chlorophosphate in S1 is 10g:100-200mL:1.5-2.4g:1.6-2.7g; The addition ratio of phosphorylated PMMA, N,N-dimethylformamide, potassium carbonate, and perfluorohexylethyl iodide in S2 is 10g: 150-200mL: 2-3g: 6-9g; The addition ratio of intermediate product, N,N-dimethylformamide, and propyltrimethoxysilane in S3 is 10g: 150-200mL: 2.2-3.7g.

4. The method for preparing the environmentally resistant composite nano-protective coating according to claim 1, characterized in that, The preparation method of the barium strontium titanate / boron nitride core-shell particles includes the following steps: A1: Tetrabutyl titanate, anhydrous ethanol (component 1), and acetylacetone are dispersed in a reaction flask; barium acetate, strontium acetate, and anhydrous ethanol (component 2) are mixed and added to the reaction flask; glacial acetic acid and deionized water are added, and the mixture is stirred at room temperature for 3-6 hours to obtain a sol; the sol is transferred to an autoclave, heated to 160-180℃, and kept at that temperature for 12-24 hours; the mixture is then washed, dried, pulverized, and calcined to obtain barium strontium titanate powder. A2: Add barium strontium titanate powder and anhydrous ethanol to a reaction flask, adjust the pH to 9-10, add tetraethyl orthosilicate, deionized water and anhydrous ethanol to the reaction flask, control the temperature at 40-60℃, keep warm and stir for 5-10 hours, centrifuge, wash and dry to obtain barium strontium titanate powder coated with silica. A3: Add boric acid, urea, anhydrous ethanol and water to a reaction flask and disperse. Add barium strontium titanate powder coated with silica and disperse. Stir at room temperature for 12-24 hours. Remove anhydrous ethanol and water by rotary evaporation. Dry, calcine, etch, wash with water, and dry again to obtain BST@BN core-shell particles. A4: Mix KH550, ethanol, and water, add BST@BN particles for dispersion, control the temperature at 60-80℃, stir and reflux for 2-4 hours, centrifuge, wash with ethanol, and dry to obtain barium strontium titanate / boron nitride core-shell particles.

5. The method for preparing the environmentally resistant composite nano-protective coating according to claim 4, characterized in that, The addition ratio of tetrabutyl titanate, anhydrous ethanol component one, acetylacetone, barium acetate, strontium acetate, anhydrous ethanol component two, glacial acetic acid, and deionized water in A1 is 3.4g: 20-30mL: 1-2g: 1.66-1.92g: 0.54-0.75g: 40-60mL: 2-3mL: 1-2mL; The addition ratio of barium strontium titanate powder, anhydrous ethanol component III, tetraethyl orthosilicate, deionized water, and anhydrous ethanol component IV in A2 is 10g: 80-160mL: 5-10g: 5-10mL: 20-40mL. In A3, the addition ratio of boric acid, urea, anhydrous ethanol, water, and barium strontium titanate powder coated with silica is 2.5-5g: 7.5-12.5g: 100-200mL: 5-10mL: 5g; The addition ratio of KH550, ethanol, water, and BST@BN particles in A4 is 0.25-0.50g: 50-100mL: 1-2mL: 5g; The specific steps for calcination in A1 are as follows: control the heating rate to 1-2℃ / min to raise the temperature to 330-350℃ and hold for 1-1.5h; control the heating rate to 2-5℃ / min to raise the temperature to 600-650℃ and hold for 2-4h. The specific drying steps in A3 are as follows: control the temperature at 60-80℃ and dry for 6-12 hours, then treat in nitrogen at 150-160℃ for 1-2 hours. The specific calcination steps in A3 are as follows: In an argon atmosphere, the temperature is increased to 300-330℃ at a rate of 5℃ / min; in a mixture of argon and ammonia with a volume ratio of 4:1, the temperature is increased to 850-900℃ at a rate of 10℃ / min and held for 3 hours; in an argon atmosphere, the temperature is decreased to 550-600℃ at a rate of 2℃ / min; in an argon atmosphere, the temperature is decreased to room temperature at a rate of 5-10℃ / min.

6. The method for preparing the environmentally resistant composite nano-protective coating according to claim 1, characterized in that, The preparation method of the HMDS-modified mesoporous silica includes the following steps: under a nitrogen atmosphere, 10g of mesoporous silica and 80-150mL of toluene are mixed, 2-5g of hexamethyldisilazane is added, the temperature is controlled at 60-90℃, and the mixture is stirred and refluxed for 4-12h. After washing and drying, HMDS-modified mesoporous silica is obtained.

7. The method for preparing the environmentally resistant composite nano-protective coating according to claim 1, characterized in that, The preparation method of the hydroxyl-terminated fluorinated polyurethane prepolymer includes the following steps: B1: Isophorone diisocyanate, dibutyltin dilaurate, and acetone are added to a reaction flask and dispersed. The temperature is controlled at 40-60℃. Hexafluorobutanol is added dropwise, and the reaction is maintained at this temperature for 2-4 hours. Diethanolamine is added dropwise, and the reaction is maintained at 0-5℃ for 1-3 hours. Acetone is removed by vacuum distillation to obtain a fluorinated diol with terminal hydroxyl groups. B2: Polytetrahydrofuran ether diol and hydroxyl-terminated fluorinated diol are dispersed in a reaction flask and the temperature is controlled at 70-90℃. Isophorone diisocyanate and dibutyltin dilaurate are added and the reaction is maintained at 70-90℃ for 2-4 hours. Then, 1,4-butanediol and propylene glycol methyl ether acetate are mixed and added to the reaction flask. The reaction is maintained at 70-80℃ for 1.5-3 hours to obtain hydroxyl-terminated fluorinated polyurethane prepolymer. The addition ratio of isophorone diisocyanate, dibutyltin dilaurate, acetone, hexafluoro-n-butanol, and 4.7-5.2g of diethanolamine in B1 is 10g:0.015-0.03g:5-10mL:7.8-8.6g; The addition ratio of polytetrahydrofuran ether diol, hydroxyl-terminated fluorinated diol, isophorone diisocyanate, dibutyltin dilaurate, 1,4-butanediol, and propylene glycol methyl ether acetate in B2 is 50-70g: 8-15g: 15-25g: 0.01-0.05g: 1-3g: 80-120g.

8. The method for preparing the environmentally resistant composite nano-protective coating according to claim 1, characterized in that, The composite nano-protective coating comprises the following raw materials in parts by weight: 35-45 parts by weight of hydroxyl-terminated fluorinated polyurethane prepolymer, 12-18 parts by weight of methylphenyl vinyl silicone resin, 20-28 parts by weight of solvent, 6-10 parts by weight of HMDS-modified mesoporous silica, 0.3-0.8 parts by weight of ultraviolet absorber, 1.5-4.5 parts by weight of dendritic phosphorus-containing fluorosilicone resin, 4-12 parts by weight of barium strontium titanate / boron nitride core-shell particles, and 10-15 parts by weight of HDI trimer curing agent.

9. The method for preparing the environmentally resistant composite nano-protective coating according to claim 1, characterized in that, The solvent is composed of propylene glycol methyl ether acetate and propylene glycol methyl ether in a mass ratio of 15-20:5-10; the ultraviolet absorber is a benzotriazole ultraviolet absorber.

10. A composite nano-protective coating resistant to environmental aging, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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