High temperature and chemical resistant insulating paint, enameled wire and preparation method

Abstract

This invention relates to the field of enameled wire technology, and more particularly to a high-temperature and chemically resistant insulating varnish, enameled wire, and preparation method. The high-temperature and chemically resistant insulating varnish comprises the following components by weight percentage: polyimide resin: 45-65%, fluorinated polyimide: 8.0-20%, aromatic amine curing agent: 5.0-15%, dimethylformamide: 10-30%, hexagonal boron nitride: 5.0-10.0%, nano-alumina: 3.0-10%, nano-silica: 2.0-5.0%, dispersant: 0.5-2.0%, and defoamer: 0.2-1.5%. This invention, by employing polyimide and fluorinated polyimide resin, combined with nanofillers and an optimized preparation process, can produce a high-performance insulating varnish widely used in aerospace, electric vehicles, industrial motors and transformers, electronic and electrical equipment, and other fields, providing reliable insulation protection for these demanding applications.

Description

Technical Field

[0001] This invention relates to the field of enameled wire technology, and more particularly to an insulating varnish, enameled wire, and preparation method that are resistant to high temperature and chemical corrosion. Background Technology

[0002] Enameled wire, a key material widely used in motors, electrical appliances, transformers, and electronic equipment, directly affects the reliability and lifespan of these devices. The core of enameled wire lies in its insulating varnish layer, which not only needs excellent insulation properties but also high mechanical strength, heat resistance, and adhesion to ensure long-term stable operation under various complex working conditions.

[0003] In modern industry and technological development, the requirements for materials in high-temperature environments are becoming increasingly stringent. Many critical devices and systems, such as aerospace engines, electric vehicle motors, industrial motors, and transformers, must operate stably for extended periods in high-temperature environments. The normal operation of these devices relies on high-quality insulating materials capable of maintaining their insulation performance and mechanical strength under high-temperature conditions. Traditional insulating varnishes, such as polyester and polyurethane varnishes, while performing well in medium and low-temperature environments, are prone to thermal degradation at high temperatures, leading to a significant decrease in insulation performance and even posing safety hazards. Therefore, developing an insulating varnish material that can operate stably in high-temperature environments has become an urgent need.

[0004] In addition, in many industrial applications, equipment not only needs to withstand high temperatures but also needs to resist various chemically corrosive environments. For example, in chemical plants, marine engineering projects, and nuclear power plants, equipment comes into contact with corrosive substances such as acids, alkalis, solvents, and salt spray. These corrosive substances can severely damage traditional insulating varnishes, leading to insulation failure and consequently affecting the safety and reliability of the equipment.

[0005] Therefore, insulating varnishes must not only have excellent high-temperature resistance, but also excellent chemical corrosion resistance to ensure long-term stable operation in harsh chemical environments. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide an insulating varnish that is resistant to high temperatures and chemical corrosion. By employing polyimide and fluorinated polyimide resin, combined with nanofillers and an optimized preparation process, the present invention can produce a high-performance insulating varnish that can be widely used in aerospace, electric vehicles, industrial motors and transformers, electronic and electrical equipment, and other fields, providing reliable insulation protection for these demanding applications.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An insulating varnish resistant to high temperatures and chemical corrosion, comprising the following components by weight percentage:

[0009] Polyimide resin: 45-65%

[0010] Fluorinated polyimide: 8.0-20%

[0011] Aromatic amine curing agents: 5.0-15%

[0012] Dimethylformamide: 10-30%

[0013] Hexagonal boron nitride: 5.0-10.0%

[0014] Nano-alumina: 3.0-10%

[0015] Nano-silica: 2.0-5.0%

[0016] Dispersant: 0.5-2.0%

[0017] Defoamer: 0.2-1.5%.

[0018] Preferably, the insulating varnish is composed of the following components by weight percentage:

[0019] Polyimide resin: 40-55%

[0020] Fluorinated polyimide: 10-15%

[0021] Aromatic amine curing agents: 8.0-12%

[0022] Dimethylformamide: 12-25%

[0023] Hexagonal boron nitride: 6.0-8.0%

[0024] Nano-alumina: 4.0-8.0%

[0025] Nano-silica: 2.0-4.0%

[0026] Dispersant: 1.0-1.5%

[0027] Defoamer: 0.3-1.0%.

[0028] As a preferred option, the fluorinated polyimide is one of DuPont's Kapton® FPI, Suzhou Xinhua Chemical Co., Ltd.'s LFPI-80, or Chemours' eflon® FEP-PI.

[0029] Preferably, the aromatic amine curing agent is selected from one of 4,4'-diaminodiphenylmethane (DDM), m-phenylenediamine, 4,4'-diaminobiphenyldiphenylmethane-4,4'-diamine (DDM), 1,3-diaminobenzene (MDA), and 4,4'-diaminodiphenyl sulfide (DDS).

[0030] Preferably, the dispersant is selected from BYK-110, Disperbyk-180, TEGO Dispers 750 W, and Solsperse20000; the defoamer is selected from BYK-024, TEGOAirex 900, Foamaster® NO 2331, and Deefo 2150.

[0031] Preferably, the surface area of ​​nano-silica is 100-300 m² / g, and the surface is treated with organosilane; the average particle size of nano-alumina is 10-50 nanometers.

[0032] Further preferred options include Evonik Aerosil R812S or Cabot Cab-O-Sil TS-720 for nano-silica and Nanophase Technologies NanOx or US Research Nanomaterials NanoTek for nano-alumina.

[0033] Furthermore, the present invention also discloses a method for preparing a high-temperature resistant and chemically resistant insulating varnish, the method comprising the following steps:

[0034] 1) Mixing of resin matrix and solvent

[0035] Mix polyimide resin (PI) and fluorinated polyimide (FPI) together in a certain proportion; add dimethylformamide (DMF) as a solvent; stir with a stirrer at room temperature for 2 hours to ensure that the resin is completely dissolved in the solvent;

[0036] 2) Add curing agent

[0037] Slowly add the aromatic amine curing agent to the resin solution; continue stirring for 1 hour to ensure that the curing agent is completely dissolved and evenly distributed;

[0038] 3) Adding additives

[0039] Add dispersant and defoamer in proportion; stir with a stirrer at room temperature for 30 minutes to ensure that the additives are evenly dispersed in the solution;

[0040] 4) Add filler

[0041] Add nano-alumina, nano-silica, and hexagonal boron nitride in sequence according to the proportions; use a high-shear dispersion device to gradually add the fillers to the mixture of matrix resin and curing agent; after each filler is added, perform high-shear dispersion for 20-30 minutes to ensure that the nano-fillers are evenly distributed in the resin solution and avoid agglomeration.

[0042] 5) Degassing treatment

[0043] The mixed solution was placed in a vacuum degassing device and degassed for 30 minutes under a vacuum of -0.09 MPa to remove air bubbles from the solution and ensure the uniformity and integrity of the paint film during coating.

[0044] Furthermore, the present invention also discloses a high-temperature resistant and chemically corrosion resistant enameled wire, wherein the insulating varnish of the enameled wire is the aforementioned insulating varnish.

[0045] Furthermore, the present invention also discloses a method for preparing the enameled wire, the method comprising the following steps:

[0046] 1) Coating

[0047] The prepared paint is uniformly coated onto the enameled wire using dip coating, spray coating, or roller coating processes; the coating speed is controlled at 5-10 m / min, and the paint film thickness is controlled at 20-25 μm to ensure uniform coating.

[0048] 2) Curing

[0049] Place the coated enameled wire in an oven and cure it by gradually increasing the temperature according to the following procedure: 100°C for 1 hour, 150°C for 1 hour, 200°C for 1 hour, 250°C for 1 hour, and 300°C for 2 hours.

[0050] 3) Cooling and post-treatment

[0051] After curing, allow the enameled wire to cool naturally to room temperature to avoid stress concentration and enamel film cracking caused by rapid cooling.

[0052] Because of the above-mentioned technical solution, this invention demonstrates innovation over existing technologies in several aspects of its high-temperature and chemically resistant insulating varnish formulation. The detailed innovations are described below:

[0053] 1. Innovative material selection

[0054] Polyimide (PI) resin: Due to its excellent high-temperature resistance and mechanical strength, polyimide resin can operate stably for extended periods in high-temperature environments above 400°C. Compared with traditional polyester and polyurethane insulating varnishes, polyimide offers higher thermal stability, significantly extending the service life of enameled wires in high-temperature environments.

[0055] Fluorinated polyimide (FPI) resin: Fluorinated polyimide is introduced into polyimide, and the introduction of fluorine significantly improves the material's chemical resistance and heat resistance. The chemical inertness of fluorine allows the insulating varnish to remain stable in extreme chemical environments, thereby broadening the application range of enameled wires, especially in corrosive environments.

[0056] 2. Applications of Nanotechnology

[0057] Nano-alumina (Al2O3): Nano-alumina possesses high hardness and thermal stability, significantly improving the mechanical strength and wear resistance of paint films. Compared to traditional fillers, nano-sized alumina particles can be more uniformly dispersed in the resin matrix, enhancing the overall performance of the paint film.

[0058] Nano-silica (SiO2): Nano-silica possesses excellent chemical stability and electrical insulation properties, enhancing the dielectric strength and chemical resistance of paint films. Compared to traditional fillers, nano-sized silica particles can more effectively improve the durability and insulation performance of paint films.

[0059] Hexagonal boron nitride (h-BN): Due to its excellent thermal conductivity and chemical corrosion resistance, hexagonal boron nitride can provide good thermal management performance in high-temperature environments. Compared with traditional fillers, hexagonal boron nitride can significantly improve the thermal conductivity and chemical corrosion resistance of the coating film, ensuring that enameled wires perform better in high-temperature and chemically corrosive environments.

[0060] 3. Optimized preparation process

[0061] High-shear dispersion equipment: Using high-shear dispersion equipment, such as ultrasonic dispersers or high-speed mixers, ensures uniform dispersion of nanofillers in the resin solution. Compared with traditional stirring methods, high-shear dispersion effectively avoids the aggregation of nanoparticles, improving the uniformity and performance of the coating film.

[0062] Vacuum degassing technology: The mixed solution is placed in a vacuum degassing device for degassing, removing air bubbles from the solution. Traditional processes easily introduce air bubbles during coating, leading to a decline in paint film quality. The application of vacuum degassing technology ensures the density and integrity of the paint film during coating.

[0063] Gradual temperature curing: A gradual temperature curing process is adopted, gradually increasing the temperature from 100°C to 300°C, with a certain holding time at each temperature stage to ensure that the paint film is fully cured at each temperature stage. Compared with single high-temperature curing, gradual temperature increase can effectively reduce stress concentration in the paint film, prevent cracking, and improve the mechanical strength and heat resistance of the paint film.

[0064] In summary, through innovative material selection, the application of nanotechnology, and optimized preparation processes, this invention surpasses existing technologies in several aspects with its high-temperature and chemically resistant insulating varnish formulation. Its superior high-temperature resistance, excellent chemical corrosion resistance, and good mechanical strength and electrical insulation properties make it widely applicable to demanding fields such as aerospace, electric vehicles, industrial motors and transformers, and electronic and electrical equipment, providing reliable insulation protection and performance assurance for these fields. Detailed Implementation

[0065] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0066] The formulations of the comparative examples and embodiments of the present invention are shown in Tables 1 and 2:

[0067] Table 1 Formulation of Examples

[0068] Components Example 1 (%) Example 2 (%) Example 3 (%) Polyimide (PI) resin 50 47 49 Fluorinated polyimide (FPI) 10 12 11 Aromatic amine curing agents (DDM) 10 10 10 Dimethylformamide (DMF) 20 23 20 Hexagonal boron nitride (h-BN) 5 5 6 Nano-alumina (Al2O3) 2 1.5 2 Nano-silica (SiO2) 2 0.5 1 dispersant 0.5 0.5 0.5 Defoamer 0.5 0.5 0.5 total 100 100 100

[0069] Table 2 Comparative Formulations

[0070] Components Comparative Example 1 (%) Comparative Example 2 Comparative example 3 (%) Comparative example 4 (%) Comparative example 5 (%) Polyimide (PI) resin 50 50 50 50 50 Fluorinated polyimide (FPI) - - 10 10 10 polyimide resin 10 - - - - Polyester resin - 10 - - - Aromatic amine curing agents (DDM) 10 10 10 10 Ethylenediamine (EDA) - - - 10 - Dimethylformamide (DMF) 20 20 20 20 20 Hexagonal boron nitride (h-BN) 5 5 - 5 9 Nano-alumina (Al2O3) 2 2 7 2 - Nano-silica (SiO2) 2 2 2 2 - dispersant 0.5 0.5 0.5 0.5 0.5 Defoamer 0.5 0.5 0.5 0.5 0.5 total 100 100 100 100 100

[0071] The specific preparation methods of the comparative examples and embodiments of the present invention are as follows:

[0072] 1. Mixing of resin matrix and solvent

[0073] Mix polyimide resin (PI), fluorinated polyimide (FPI), polyimide resin (if any), and polyester resin (if any) together in proportion; add dimethylformamide (DMF) as a solvent; stir with a stirrer at room temperature for 2 hours to ensure that the resin is completely dissolved in the solvent.

[0074] 2. Add curing agent

[0075] Slowly add the aromatic amine curing agent (4,4'-diaminodiphenylmethane, DDM) to the resin solution; continue stirring for 1 hour to ensure that the curing agent is completely dissolved and evenly distributed.

[0076] 3. Adding additives

[0077] Add a high-temperature resistant dispersant (such as BYK-110) and a high-temperature resistant defoamer (BYK-024) in proportion; stir with a stirrer at room temperature for 30 minutes to ensure that the additives are evenly dispersed in the solution.

[0078] 4. Add filler

[0079] Add nano-alumina (Al2O3), nano-silica (SiO2), and hexagonal boron nitride in sequence according to the specified ratio; use a high-shear dispersion device, such as an ultrasonic disperser or a high-speed mixer, to disperse at 2000 rpm for 1 hour to ensure that the nanofiller is evenly distributed in the resin solution and to avoid agglomeration.

[0080] 5. Preprocessing

[0081] The mixed solution was placed in a vacuum degassing device and degassed for 30 minutes under a vacuum of -0.09 MPa to remove air bubbles from the solution and ensure the uniformity and integrity of the paint film during coating.

[0082] Coating and curing

[0083] 1. Coating

[0084] The prepared paint is uniformly coated onto the enameled wire using dip coating, spray coating, or roller coating processes; the coating speed is controlled at 5-10 m / min, and the paint film thickness is controlled at 20-25 μm to ensure uniform coating.

[0085] 2. Curing

[0086] Place the coated enameled wire in an oven and cure it by gradually increasing the temperature according to the following procedure:

[0087] Keep warm at 100°C for 1 hour

[0088] Keep warm at 150°C for 1 hour

[0089] Keep warm at 200°C for 1 hour

[0090] Keep warm at 250°C for 1 hour

[0091] Keep warm at 300°C for 2 hours;

[0092] Each temperature stage must ensure full curing to form a dense, heat-resistant, and chemically resistant paint film.

[0093] 3. Cooling and post-treatment

[0094] After curing, allow the enameled wire to cool naturally to room temperature to avoid stress concentration and enamel film cracking caused by rapid cooling. Then, conduct quality inspections on the enameled wire, testing the uniformity, adhesion, high-temperature resistance, and chemical corrosion resistance of the enamel film to ensure it meets technical requirements.

[0095] To evaluate the performance of the insulating varnishes in the various embodiments and comparative examples, the following detailed tests were conducted on the high-temperature resistance, chemical corrosion resistance, mechanical strength, and electrical insulation properties of the varnish films:

[0096] 1. High-temperature resistance test

[0097] Method for determining thermal degradation temperature:

[0098] Equipment: Thermogravimetric analyzer (TGA).

[0099] step:

[0100] Cut the enameled wire sample into an appropriate size (approximately 10 mg); place it in a platinum crucible of a thermogravimetric analyzer; heat it from room temperature to 600°C at a heating rate of 10°C / min; record the mass change curve of the sample with temperature; determine the thermal degradation temperature, i.e., the temperature at which the sample mass is reduced by 5%.

[0101] Method for determining weight loss rate:

[0102] step:

[0103] Place the enameled wire sample at a predetermined high temperature (e.g., 300°C) for 2 hours; after cooling to room temperature, weigh the sample.

[0104] The formula for calculating the weight loss rate is:

[0105] Weight loss rate (%) = (initial mass - mass after insulation) / initial mass * 100.

[0106] 2. Chemical corrosion resistance test

[0107] Acid corrosion test:

[0108] step:

[0109] Immerse the enameled wire sample in a 10% sulfuric acid solution for 24 hours at room temperature; remove the sample, rinse with deionized water and dry.

[0110] Weigh the sample and calculate the rate of change of weight using the following formula:

[0111] Weight change rate (%) = (initial mass - mass after corrosion) / (initial mass) * 100.

[0112] Alkali corrosion test:

[0113] step:

[0114] Immerse the enameled wire sample in a 10% sodium hydroxide solution for 24 hours at room temperature; remove the sample, rinse with deionized water and dry.

[0115] Weigh the sample and calculate the rate of change of weight, using the same formula as above.

[0116] Salt spray corrosion test:

[0117] Equipment: Salt spray test chamber.

[0118] step:

[0119] Place the enameled wire sample into a salt spray test chamber; conduct a corrosion test in a 5% sodium chloride solution atomization environment for 24 hours; remove the sample, rinse with deionized water and dry; weigh the sample mass and calculate the weight change rate using the same formula as above.

[0120] 3. Mechanical strength test

[0121] Tensile strength test:

[0122] Equipment: Universal testing machine.

[0123] step:

[0124] Fix the enameled wire sample in the fixture of the testing machine; stretch the sample at a speed of 10 mm / min until it breaks; record the maximum tensile force and calculate the tensile strength using the formula:

[0125] Tensile strength (MPa) = maximum tensile force / initial cross-sectional area of ​​the sample.

[0126] Bending strength test:

[0127] Equipment: Three-point bending tester.

[0128] step:

[0129] Place the enameled wire sample on a three-point bending apparatus; apply a load at a speed of 2 mm / min until the sample bends or breaks; record the maximum bending force and calculate the bending strength using the following formula:

[0130] Bending strength (MPa) = 3 × maximum bending force × support span 2 × sample width × sample thickness 2 Bending strength (MPa) = 2 × sample width × sample thickness 2 3 × maximum bending force × support span

[0131] 4. Electrical insulation performance test

[0132] Methods for measuring dielectric strength:

[0133] Equipment: Dielectric strength tester.

[0134] step:

[0135] Fix the enameled wire sample between the electrodes of the testing instrument; gradually increase the voltage until the sample breaks down.

[0136] Record the breakdown voltage and calculate the dielectric strength using the following formula:

[0137] Dielectric strength (kV / mm) = Breakdown voltage Sample thickness Dielectric strength (kV / mm) = Sample thickness Breakdown voltage

[0138] Methods for measuring volume resistivity:

[0139] Equipment: Volume resistivity meter.

[0140] step:

[0141] The enameled wire sample is fixed between the electrodes of the measuring instrument; a constant voltage is applied, and the current passing through the sample is measured.

[0142] The formula for calculating volume resistivity is:

[0143] Volume resistivity (Ω·cm) = Applied voltage × Sample cross-sectional area / Sample length. Table 3 Experimental Results

[0144] Examples / Comparative Examples Thermal degradation temperature (°C) Weight loss rate (%) Weight change (%) after acid etching Weight change (%) after alkaline corrosion Weight change (%) after salt spray corrosion Tensile strength (MPa) Bending strength (MPa) Dielectric strength (kV / mm) Volume resistivity (Ω·cm) Example 1 420 1.5 0.2 0.3 0.1 85 150 45 1.0×10^15 Example 2 430 1.3 0.1 0.2 0.1 90 155 48 1.2×10^15 Example 3 425 1.4 0.2 0.2 0.1 88 152 46 1.1×10^15 Comparative Example 1 340 6.0 1.5 2.0 1.0 55 95 20 4.0×10^12 Comparative Example 2 335 8.5 3.2 3.7 2.9 57 88 12 6.5×10^12 Comparative Example 3 355 3.8 0.9 1.4 0.7 62 105 28 3.5×10^12 Comparative Example 4 360 2.5 0.8 1.3 0.6 65 110 30 3.0×10^12 Comparative Example 5 370 4.0 0.7 1.0 0.5 70 120 32 4.5×10^12

[0145] Results Analysis

[0146] Experimental results show that the embodiments of the present invention are significantly superior to the comparative examples in terms of high-temperature resistance, chemical corrosion resistance, mechanical strength, and electrical insulation properties. In particular:

[0147] High temperature resistance: The thermal degradation temperature of the examples is above 420°C, which is significantly higher than that of the comparative example, and the weight loss rate is low, showing excellent high temperature resistance.

[0148] Chemical corrosion resistance: The weight changes of the examples after acid, alkali and salt spray corrosion were much smaller than those of the comparative examples, indicating better chemical corrosion resistance.

[0149] Mechanical strength: The tensile and flexural strengths of the embodiment are significantly higher than those of the comparative example, showing higher mechanical strength.

[0150] Electrical insulation performance: The dielectric strength and volume resistivity of the embodiment are significantly better than those of the comparative example, indicating that it has better electrical insulation performance.

[0151] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A high-temperature resistant and chemically corrosion resistant enameled wire insulating varnish, characterized in that, The insulating varnish consists of the following components by weight percentage: 50% polyimide resin 10% fluorinated polyimide 10% aromatic amine curing agent 20% dimethylformamide 5% hexagonal boron nitride 2% nano-alumina 2% Nano-silica Dispersant 0.5% Defoamer 0.5%; The aromatic amine curing agent selected is 4,4'-diaminodiphenylmethane.

2. A high-temperature resistant and chemically corrosion resistant enameled wire insulating varnish, characterized in that, This insulating varnish consists of the following components by weight percentage: 47% polyimide resin 12% Fluorinated polyimide 10% aromatic amine curing agent Dimethylformamide 23% 5% hexagonal boron nitride 1.5% nano-alumina 0.5% nano-silica Dispersant 0.5% Defoamer 0.5%; The aromatic amine curing agent selected is 4,4'-diaminodiphenylmethane.

3. A high-temperature resistant and chemically corrosion resistant enameled wire insulating varnish, characterized in that, The insulating varnish consists of the following components by weight percentage: Polyimide resin 49% 11% Fluorinated polyimide 10% aromatic amine curing agent 20% dimethylformamide 6% hexagonal boron nitride 2% nano-alumina 1% Nano-silica Dispersant 0.5% Defoamer 0.5%; The aromatic amine curing agent selected is 4,4'-diaminodiphenylmethane.

4. A high-temperature resistant and chemically resistant enameled wire insulating varnish according to any one of claims 1-3, characterized in that, The dispersant is selected from one of BYK-110, Disperbyk-180, TEGO Dispers 750 W, and Solsperse 20000; the defoamer is selected from one of BYK-024, TEGO Airex 900, Foamaster® NO 2331, and Deefo 2150.

5. A high-temperature resistant and chemically resistant enameled wire insulating varnish according to any one of claims 1-3, characterized in that, The surface area of ​​nano-silica is 100-300 m² / g, and the surface is treated with organosilane; the average particle size of nano-alumina is 10-50 nanometers.

6. A method for preparing a high-temperature resistant and chemically resistant enameled wire insulating varnish according to any one of claims 1-5, characterized in that, The method includes the following steps: 1) Mixing of resin matrix and solvent Mix polyimide resin and fluorinated polyimide together in a certain proportion; add dimethylformamide as a solvent; stir at room temperature for 2 hours using a stirrer to ensure that the resin matrix is ​​completely dissolved in the solvent; 2) Add curing agent Slowly add the aromatic amine curing agent to the resin solution; continue stirring for 1 hour to ensure that the curing agent is completely dissolved and evenly distributed; 3) Adding additives Add dispersant and defoamer in proportion; stir with a stirrer at room temperature for 30 minutes to ensure that the additives are evenly dispersed in the solution; 4) Add filler Nano-alumina, nano-silica, and hexagonal boron nitride are added sequentially in proportion; a high-shear dispersion device is used to disperse the nanofiller at 2000 rpm for 1 hour to ensure uniform distribution of the nanofiller in the solution and avoid agglomeration. 5) Degassing treatment The mixed solution was placed in a vacuum degassing device and degassed for 30 minutes under a vacuum of -0.09 MPa to remove air bubbles from the solution and ensure the uniformity and integrity of the paint film during coating.

7. A high-temperature resistant and chemically corrosion resistant enameled wire, characterized in that: The insulating varnish of the enameled wire is any one of the insulating varnishes described in items 1-5.

8. The method for preparing enameled wire according to claim 7, characterized in that: The method includes the following steps: 1) Coating The prepared paint is uniformly coated onto the enameled wire using dip coating, spray coating or roller coating processes; the coating speed is controlled at 5-10 m / min and the paint film thickness is controlled at 20-25 μm to ensure uniform coating. 2) Curing Place the coated enameled wire in an oven and cure it by gradually increasing the temperature according to the following procedure: 100°C for 1 hour, 150°C for 1 hour, 200°C for 1 hour, 250°C for 1 hour, and 300°C for 2 hours. 3) Cooling and post-treatment After curing, allow the enameled wire to cool naturally to room temperature to avoid stress concentration and enamel film cracking caused by rapid cooling.