An insulating paint, an enameled wire and a preparation method thereof

Abstract

The present application relates to the technical field of enameled wire, and particularly relates to an enameled wire insulating paint and enameled wire suitable for high-frequency electricity. The dry components of the insulating paint are composed of the following components in percentage by mass: polyimide: 25-40%, polyethylene terephthalate: 15-25%, fluorine-containing polymer: 5-15%, phenolic resin: 5.0-10%, melamine formaldehyde resin: 3.0-8.0%, silicon resin: 3.0-8.0%, nano-aluminum oxide: 5.0-15%, nano-silicon dioxide: 5.0-15%, ceramic microparticles: 3.0-8.0%, hindered amine light stabilizer: 1.0-5.0%, dioctyl phthalate: 2.0-8.0%. The present application has excellent high-frequency electrical performance, heat resistance and mechanical strength, and is suitable for high-frequency and high-efficiency applications in modern electronic devices, such as 5G communication devices, high-speed motors and power electronic devices.

Description

Technical Field

[0001] This invention relates to the field of enameled wire technology, and more particularly to an enameled wire insulating varnish and enameled wire suitable for high-frequency electrical applications. Background Technology

[0002] Enamelled wire is an important conductor widely used in motors, electrical appliances, transformers, and electronic equipment. Its main function is to conduct and insulate current through the combination of a conductive core and an insulating layer. Enamelled wire typically uses copper or aluminum as the conductor, with one or more layers of insulating varnish on the outside. With the continuous development of electronic equipment, especially the increasing demand for high frequency, high efficiency, and miniaturization, the performance requirements for enamelled wire are also constantly improving.

[0003] Traditional enameled wires are prone to increased dielectric loss and decreased insulation performance in high-frequency applications, leading to reduced power transmission efficiency. Furthermore, as equipment power increases, operating temperatures rise, and the heat resistance of traditional enameled wires is insufficient for long-term stable operation in high-temperature environments. Additionally, in high-frequency equipment and miniaturized applications, enameled wires require high mechanical strength to resist various mechanical stresses and wear; traditional materials often cannot simultaneously achieve both insulation performance and mechanical strength.

[0004] To meet the requirements of modern high-frequency electrical equipment, enameled wire must possess the following characteristics:

[0005] 1. Excellent high-frequency electrical performance: Enameled wire needs to maintain a low dielectric constant and low dielectric loss in high-frequency operating environments to ensure the efficiency and stability of power transmission.

[0006] 2. High heat resistance: Enamelled wire must be able to withstand high temperature environments and maintain long-term stable insulation performance and mechanical strength, making it suitable for high-temperature applications;

[0007] 3. High mechanical strength: In high-frequency and miniaturized equipment, enameled wires need to have good mechanical strength and wear resistance to ensure their reliability and durability during operation. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to provide an enameled wire insulation varnish suitable for high-frequency electrical applications, possessing excellent high-frequency electrical properties, heat resistance, and mechanical strength, and applicable to high-frequency, high-efficiency applications in modern electronic equipment, such as 5G communication equipment, high-speed motors, and power electronic devices.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] An enameled wire insulating varnish suitable for high-frequency electrical applications, wherein the dry components of the varnish consist of the following components by weight percentage:

[0011] Polyimide: 25-40%

[0012] Polyethylene terephthalate: 15-25%

[0013] Fluoropolymers: 5-15%

[0014] Phenolic resin: 5.0-10%

[0015] Melamine-formaldehyde resin: 3.0-8.0%

[0016] Silicone resin: 3.0-8.0%

[0017] Nano-alumina: 5.0-15%

[0018] Nano-silica: 5.0-15%

[0019] Ceramic microparticles: 3.0-8.0%

[0020] Hindered amine light stabilizer: 1.0-5.0%

[0021] Dioctyl phthalate: 2.0-8.0%.

[0022] The functions of each component in the formulation of this invention are as follows:

[0023] Polyimide (PI): Offers excellent heat resistance, mechanical strength, and electrical insulation properties. Polyimide materials exhibit good stability at high temperatures, making them suitable for high-temperature environments.

[0024] Polyethylene terephthalate (PET): Enhances the mechanical strength and thermal stability of materials, while improving their molding and processing properties. PET also has good heat resistance and insulation properties.

[0025] Polytetrafluoroethylene (PTFE): Offers extremely low dielectric constant and dielectric loss, enhancing the electrical insulation properties of materials, making it particularly suitable for high-frequency applications. PTFE also exhibits excellent chemical resistance and high-temperature resistance.

[0026] Phenolic resin: As a curing agent, it enhances the mechanical strength and heat resistance of materials, and provides excellent thermal stability and insulation properties;

[0027] Melamine-formaldehyde resin: further improves the mechanical strength and heat resistance of the material, and enhances the wear resistance and surface hardness of the material;

[0028] Methylphenyl silicone resin: enhances the heat resistance and electrical insulation properties of materials, while also improving the weather resistance and chemical stability of materials;

[0029] Nano-alumina (Al2O3): Provides high mechanical strength and wear resistance, and enhances the thermal conductivity and electrical insulation properties of materials. The nanoscale particle size contributes to uniform dispersion, improving material properties.

[0030] Nano-silica (SiO2): Enhances the mechanical strength and insulation properties of materials, while also improving their thermal stability and wear resistance;

[0031] Boron nitride (BN): provides excellent electrical insulation properties and thermal conductivity, and enhances the heat resistance and wear resistance of materials;

[0032] Hindered amine light stabilizers (HALS): enhance the resistance of materials to ultraviolet aging and extend the service life of materials;

[0033] Dioctyl phthalate (DOP): As a plasticizer, it provides materials with flexibility and processability, and improves the mechanical properties and fatigue resistance of materials.

[0034] Preferably, the dry component of the insulating varnish consists of the following components by mass percentage:

[0035] Polyimide: 30-35%

[0036] Polyethylene terephthalate: 18-22%

[0037] Fluoropolymers: 8.0-12%

[0038] Phenolic resin: 5.0-8.0%

[0039] Melamine-formaldehyde resin: 4.0-6.0%

[0040] Silicone resin: 4.0-6.0%

[0041] Nano-alumina: 6.0-10%

[0042] Nano-silica: 6.0-10%

[0043] Ceramic microparticles: 4.0-6.0%

[0044] Hindered amine light stabilizer: 1.5-3.0%

[0045] Dioctyl phthalate: 3.0-5.0%.

[0046] Preferably, the fluoropolymer is selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, perfluoroalkoxy polymer, ethylene-tetrafluoroethylene copolymer and fluoroethylene-propylene copolymer.

[0047] Preferably, the silicone resin is selected from one or more of methyl silicone resin, phenyl silicone resin and methylphenyl silicone resin.

[0048] Preferably, the average particle size of nano-silica is 50-100 nanometers, and the specific surface area is 100-150 m² / g; the average particle size of nano-alumina is 10-50 nanometers, and the specific surface area is 200-300 m² / g.

[0049] As a preferred option, the ceramic microparticles are boron nitride with a particle size of 20-100 nanometers and a specific surface area of ​​100-200 m² / g.

[0050] Furthermore, the present invention also discloses a method for preparing the enameled wire insulating varnish, the method comprising the following steps:

[0051] 1) Dissolution and mixing of matrix resin

[0052] Weigh polyimide (PI), polyethylene terephthalate (PET), and polytetrafluoroethylene (PTFE) according to the formula ratio; add an appropriate amount of N-methylpyrrolidone (NMP) as a solvent to a stirrer, and add the above resin; stir at 600-800 rpm for 2-3 hours to ensure that the resin is completely dissolved and uniformly mixed;

[0053] 2) Addition of curing agent

[0054] Weigh the phenolic resin, melamine-formaldehyde resin, and methylphenyl silicone resin according to the formula ratio; gradually add the curing agent to the matrix resin solution; continue stirring at 600-800 rpm for 1-1.5 hours to ensure uniform mixing;

[0055] 3) Dispersion of fillers and additives

[0056] Weigh nano-alumina, nano-silica, and boron nitride according to the formula ratio; 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 uniform dispersion; finally, add hindered amine light stabilizer (HALS) and dioctyl phthalate (DOP) and continue stirring for 30-40 minutes.

[0057] Preferably, the high-shear dispersion equipment uses an ultrasonic disperser or a high-shear mixer, with the ultrasonic power of the ultrasonic disperser being 200-300 W and the high-shear mixing speed of the high-shear mixer being 3000-5000 rpm.

[0058] Furthermore, the present invention also discloses an enameled wire suitable for high-frequency electrical applications, which is prepared by uniformly coating the insulating varnish onto copper wire using a coating device, followed by high-temperature drying and curing.

[0059] Furthermore, this invention also discloses a method for preparing enameled wire suitable for high-frequency electrical applications, wherein the coated copper wire undergoes the following multiple stages of high-temperature drying and curing:

[0060] Pre-baking: 80-100°C, 10-12 minutes;

[0061] Medium-temperature drying: 150-180°C, 15-18 minutes;

[0062] High temperature curing: 250-300°C, 30-40 minutes.

[0063] This invention significantly improves the high-frequency electrical properties, heat resistance, and mechanical strength of enameled wires by optimizing the formulation and preparation process of the insulating varnish. The specific technical effects are as follows:

[0064] 1) Improved high-frequency electrical performance: By introducing fluoropolymers such as polytetrafluoroethylene (PTFE) and ceramic microparticles, the enameled wire of this invention has a low dielectric constant and low dielectric loss, exhibiting excellent electrical insulation performance in high-frequency applications and improving power transmission efficiency; the use of various high-performance resins and nanofillers enhances the insulation of the varnish film and significantly reduces leakage current and corona discharge.

[0065] 3) Enhanced heat resistance:

[0066] The introduction of high heat-resistant materials such as polyimide (PI) and methylphenyl silicone resin enables enameled wires to maintain stable insulation performance in high-temperature environments, significantly improving their heat resistance and enabling them to withstand higher operating temperatures. Furthermore, the selection and optimization of materials enhance the thermal stability of the enamel film at high temperatures, reducing thermal degradation and performance decline.

[0067] 4) Improved mechanical strength and wear resistance:

[0068] The addition of nano-alumina (Al2O3) and nano-silica (SiO2) significantly improves the mechanical strength and wear resistance of the coating film, enabling the enameled wire to exhibit higher durability under mechanical stress and friction environments. Furthermore, the use of plasticizers (such as dioctyl phthalate (DOP)) enhances the flexibility of the coating film and the adhesion of the copper wire, thereby improving the reliability of the enameled wire under bending and tensile conditions. Detailed Implementation

[0069] 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.

[0070] The formulations of the comparative examples and embodiments of this invention are shown in Table 1:

[0071] Table 1 Formulations of rubber compositions in the examples and comparative examples

[0072] Element Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 polyimide 30% 33% 18% 40% 40% 35% 35% PET 20% 18% 22% 25% 20% 20% 20% PTFE 10% 8% 12% - - 10% 10% Phenolic resin 6% 5% 8% 10% 6% 6% 6% melamine-formaldehyde resin 5% 4% 6% 6% 5% 5% 5% Methylphenyl silicone resin 5% 4% 5% - 5% - 5% Nano aluminum oxide 7% 8% 6% 7% 7% 7% 7% Nano silica 6% 8% 10% 6% 6% 6% 6% Boron nitride (BN) 5% 5% 7% - 5% 5% - HALS 2% 2% 2% 2% 2% 2% 2% DOP 4% 5% 4% 4% 4% 4% 4%

[0073] The preparation methods for all examples and comparative examples are the same, and the specific steps are as follows:

[0074] 1) Dissolution and mixing of the matrix resin:

[0075] Weigh polyimide (PI), polyethylene terephthalate (PET), and fluoropolymers (such as PTFE or PVDF) according to the formula ratio; add an appropriate amount of N-methylpyrrolidone (NMP) as a solvent in a stirrer, and add the above resin; stir at 700 rpm for 3 hours to ensure that the resin is completely dissolved and uniformly mixed.

[0076] 2) Addition of curing agent:

[0077] Weigh the phenolic resin, melamine-formaldehyde resin, and methylphenyl silicone resin according to the formula ratio; gradually add the curing agent to the matrix resin solution and continue stirring at 700 rpm for 1.5 hours to ensure uniform mixing.

[0078] 3) Dispersion of fillers and additives:

[0079] Weigh nano-alumina, nano-silica, and boron nitride according to the formula ratio. Using a high-shear dispersion device (such as an ultrasonic disperser or a high-shear mixer), gradually add the fillers to the mixture of matrix resin and curing agent. After each filler is added, perform high-shear dispersion for 30 minutes to ensure uniform dispersion. Finally, add hindered amine light stabilizer (HALS) and dioctyl phthalate (DOP) and continue stirring for 40 minutes.

[0080] 4) Coating and curing:

[0081] The prepared insulating varnish is evenly coated onto the copper wire using a coating equipment; the coated copper wire then undergoes the following multiple stages of high-temperature drying and curing:

[0082] Pre-baking: 90°C, 12 minutes;

[0083] Medium-temperature drying: 165°C, 18 minutes;

[0084] High temperature curing: 275°C, 35 minutes.

[0085] 1. High-frequency electrical performance testing

[0086] Test equipment: LCR bridge or high-frequency dielectric tester;

[0087] Sample preparation: Cut the enameled wire material into a size and shape suitable for the testing instrument, ensuring that the sample surface is flat and free of contamination.

[0088] Equipment calibration: Use standard samples to calibrate the LCR bridge or high-frequency dielectric tester to ensure the accuracy of the test results.

[0089] Test conditions: Frequency: 1MHz, Temperature: Room temperature (25°C);

[0090] Measurement: Place the sample in the test fixture, ensuring good contact with the test electrode; record the data for dielectric constant and dielectric loss.

[0091] Data analysis: The lower the dielectric constant and dielectric loss values, the better the high-frequency electrical performance of the material.

[0092] 2. Heat resistance test

[0093] Insulation and mechanical properties under high temperature conditions

[0094] Testing instrument: Thermogravimetric analysis (TGA).

[0095] Sample preparation: Weigh an appropriate amount of enameled wire material (5-10 mg) and place it in the TGA sample tray.

[0096] Test conditions: Temperature range: room temperature to 600°C, heating rate: 10°C / min;

[0097] Measurement: Start the TGA equipment and record the mass loss curve of the sample as temperature changes.

[0098] Data analysis: The higher the weight loss temperature (e.g., 5% weight loss temperature), the better the heat resistance of the material.

[0099] 3. Mechanical strength and abrasion resistance tests

[0100] Testing equipment: tensile testing machine, Taber abrasion testing machine;

[0101] Tensile strength test:

[0102] Sample preparation: Prepare standard tensile test specimens from the enameled wire samples;

[0103] Test conditions: Tensile rate: 10 mm / min;

[0104] Measurement: Install the specimen in the fixture of the tensile testing machine, start the equipment, and record the maximum tensile force when the specimen is stretched to break.

[0105] Data analysis: Tensile strength (MPa) = Maximum tensile force (N) / Initial cross-sectional area (mm²);

[0106] The higher the tensile strength, the better the mechanical strength of the material.

[0107] Abrasion resistance test:

[0108] Sample preparation: Fix the enameled wire sample onto the sample tray of the Taber abrasion tester.

[0109] Test conditions:

[0110] Grinding wheel type: CS-10; Load: 1000g; Speed: 60 rpm; Rotation speed: 1000 rpm;

[0111] Measurement: Start the Taber abrasion tester and record the mass loss of the sample after 1000 revolutions.

[0112] Data analysis: Abrasion resistance (mg / 1000 rpm) = Mass loss (mg) / 1000 rpm;

[0113] The smaller the mass loss, the better the wear resistance of the material.

[0114] Performance Test Table

[0115] Performance indicators Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Dielectric constant (@1MHz) 2.5 2.4 2.6 3.5 3.4 2.8 3.6 Dielectric loss (@1MHz) 0.003 0.002 0.003 0.01 0.009 0.006 0.011 Heat resistance (TGA temperature of weight loss) 350°C 360°C 355°C 300°C 310°C 305°C 290°C Tensile strength (MPa) 100 105 102 80 85 90 95 Abrasion resistance (mg / 1000 rpm) 20 18 19 35 32 30 38

[0116] Through the comparative tests of the above multiple embodiments and comparative examples, the following conclusions can be drawn:

[0117] High-frequency electrical performance: The enameled wire in the embodiment exhibits a lower dielectric constant and dielectric loss, which is significantly better than the comparative example.

[0118] Heat resistance: The enameled wire in the examples has better thermal stability at high temperatures, and its weight loss temperature is significantly higher than that of the comparative example.

[0119] Mechanical strength and abrasion resistance: The enameled wire in the examples exhibits higher tensile strength and lower abrasion resistance, demonstrating higher mechanical strength and durability.

[0120] 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 type of enameled wire insulation varnish suitable for high-frequency electrical applications, characterized in that, The dry components of this insulating varnish consist of the following components by mass percentage: Polyimide: 25-40% Polyethylene terephthalate: 15-25% Fluoropolymers: 5-15% Phenolic resin: 5.0-10% Melamine-formaldehyde resin: 3.0-8.0% Silicone resin: 3.0-8.0% Nano-alumina: 5.0-15% Nano-silica: 5.0-15% Ceramic microparticles: 3.0-8.0% Hindered amine light stabilizer: 1.0-5.0% Dioctyl phthalate: 2.0-8.0%; The fluoropolymer is selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, perfluoroalkoxy polymer, ethylene-tetrafluoroethylene copolymer and fluoroethylene-propylene copolymer; The silicone resin is selected from one or more of methyl silicone resin, phenyl silicone resin, and methylphenyl silicone resin; The average particle size of nano-silica is 50-100 nanometers, and the specific surface area is 100-150 m² / g; the average particle size of nano-alumina is 10-50 nanometers, and the specific surface area is 200-300 m² / g. The ceramic microparticles are made of boron nitride, with a particle size of 20-100 nanometers and a specific surface area of ​​100-200 m² / g.

2. The enameled wire insulating varnish suitable for high-frequency electrical applications according to claim 1, characterized in that, The dry components of this insulating varnish consist of the following components by mass percentage: Polyimide: 30-35% Polyethylene terephthalate: 18-22% Fluoropolymers: 8.0-12% Phenolic resin: 5.0-8.0% Melamine-formaldehyde resin: 4.0-6.0% Silicone resin: 4.0-6.0% Nano-alumina: 6.0-10% Nano-silica: 6.0-10% Ceramic microparticles: 4.0-6.0% Hindered amine light stabilizer: 1.5-3.0% Dioctyl phthalate: 3.0-5.0%.

3. The method for preparing the enameled wire insulating varnish according to any one of claims 1-2, characterized in that, The method includes the following steps: 1) Dissolution and mixing of the matrix resin Weigh the polyimide, polyethylene terephthalate, and fluoropolymer according to the formula ratio; add an appropriate amount of N-methylpyrrolidone as a solvent to the stirrer, and add the above resin; stir at 600-800 rpm for 2-3 hours to ensure that the resin is completely dissolved and uniformly mixed; 2) Addition of curing agent Weigh the phenolic resin, melamine-formaldehyde resin, and silicone resin according to the formula ratio; gradually add the curing agent to the matrix resin solution, and continue stirring at 600-800 rpm for 1-1.5 hours to ensure uniform mixing; 3) Dispersion of fillers and additives Weigh the nano-alumina, nano-silica, and ceramic microparticles according to the formula ratio; 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 uniform dispersion; finally, add the hindered amine light stabilizer and dioctyl phthalate, and continue stirring for 30-40 minutes.

4. The preparation method according to claim 3, characterized in that, High-shear dispersion equipment uses an ultrasonic disperser or a high-shear mixer. The ultrasonic power of the ultrasonic disperser is 200-300 W, and the high-shear mixing speed of the high-shear mixer is 3000-5000 rpm.

5. An enameled wire suitable for high-frequency electrical applications, characterized in that, The insulating varnish of the enameled wire as described in any one of claims 1-2 is uniformly coated onto copper wire using a coating equipment, and then dried and cured at high temperature.

6. The method for preparing enameled wire suitable for high-frequency electrical applications as described in claim 5, characterized in that, The coated copper wires undergo the following multiple stages of high-temperature drying and curing: Pre-baking: 80-100°C, 10-12 minutes; Medium-temperature drying: 150-180°C, 15-18 minutes; High temperature curing: 250-300°C, 30-40 minutes.