High temperature dielectric films based on aromatic ring crosslinked polyetherimide and preparation and use thereof

Abstract

The application discloses a high-temperature dielectric film based on aromatic ring cross-linked polyetherimide and preparation and application thereof. The film is prepared by introducing benzene hexacarboxylic acid trianhydride as an aromatic ring cross-linking agent to build a covalent cross-linking network between polyetherimide molecular chains, so that the thermal stability and insulation performance are synergistically improved at high temperatures. The discharge energy density of the film at 150 DEG C and 200 DEG C is as high as 6.34 J / cm 3 and 6.05 J / cm 3 respectively, the breakdown strength is increased by about 50% compared with conventional polyetherimide, and the dielectric loss is lower than 5*10 ‑3 . The material is suitable for a dielectric layer of a high-temperature film capacitor and is widely applied to electric vehicles, aerospace and renewable energy storage systems.

Description

Technical Field

[0001] This invention belongs to the field of polymer dielectric materials technology, specifically relating to high-temperature dielectric films based on aromatic ring crosslinked polyetherimide and their preparation and application. Background Technology

[0002] As electric vehicles, aerospace power electronics, and renewable energy converters develop towards higher power density and greater integration, the operating temperature requirements for dielectric capacitors have generally increased to above 125℃, and even reached the harsh environment of 150–200℃. As the core insulating material of capacitors, dielectric films must maintain high dielectric strength, low loss factor, and long-term stability at high temperatures. Currently, commercially available film capacitors mainly use biaxially oriented polypropylene (BOPP) as the dielectric material. While BOPP has advantages such as low dielectric loss and high breakdown field strength at room temperature, its glass transition temperature is relatively low, and the upper limit of its long-term operating temperature is usually no more than 85℃. At high temperatures, the molecular chain movement of BOPP intensifies, and the crystalline regions are easily damaged, leading to a significant increase in carrier mobility, a decrease in resistivity, and a sharp increase in dielectric loss, ultimately causing premature capacitor failure. Therefore, BOPP cannot meet the requirements for long-term reliable operation under high temperature and high field conditions.

[0003] To improve the high-temperature performance of polymer dielectric materials, research has mainly been carried out along the following two approaches: 1. Nanocomposite Strategy: Introducing highly insulating nanoparticles (such as SiO2, Al2O3, BN, etc.) into a polymer matrix (such as polyimide, epoxy resin) to suppress space charge injection and migration, thereby improving high-temperature insulation performance. However, this method faces problems such as easy agglomeration of nanoparticles, poor compatibility with the matrix, and numerous interface defects, leading to reduced film uniformity and dispersed breakdown performance; at the same time, the complex preparation process also increases costs, making it difficult to meet the requirements of large-scale continuous production.

[0004] 2. Organic small molecule doping / blending: By introducing small molecules with high dipole moments or deep trapping energy levels (such as cyano compounds and phthalocyanine derivatives), the dielectric constant and high-temperature charge trapping characteristics of polymers can be improved to a certain extent. However, small molecules are prone to migration and volatilization at high temperatures, causing performance drift. After long-term thermal aging, phase separation may occur, leading to deterioration of dielectric properties.

[0005] Polyetherimide (PEI), with its main chain containing ether bonds and imide rings, possesses both good processability and excellent thermal stability (glass transition temperature of approximately 215 °C), and is considered a potential high-temperature dielectric material. However, studies have found that its high-temperature insulation properties are still limited by the stacking of aromatic rings in its molecular structure: under the combined effects of high temperature and high electric field, the π–π conjugated channels formed by the benzene rings promote carrier hopping conduction, resulting in a sharp decrease in resistivity with increasing temperature and a significant increase in dielectric loss. Although charge migration can be suppressed by reducing the aromatic density or introducing side chain modifications, this often sacrifices the thermal stability or mechanical strength of the material (Nature Communications | (2023)14:2406).

[0006] In summary, existing technologies have not effectively resolved the contradiction between maintaining high thermal stability and high-temperature insulation at high temperatures. Developing a novel dielectric film that can both maintain the intrinsic thermal stability of polyetherimide and suppress high-temperature charge carrier migration has become an urgent technological need in this field. To this end, this invention proposes a controlled aromatic ring crosslinking strategy to construct a stable three-dimensional network structure between polyetherimide molecular chains, aiming to block high-temperature charge migration channels and thus achieve a breakthrough in the comprehensive dielectric properties of the film under high temperature and high field conditions. Summary of the Invention

[0007] The purpose of this invention is to provide a high-temperature dielectric film based on aromatic ring crosslinked polyetherimide. A covalent network is constructed between molecular chains by using a triphenylene hexacarboxylic acid trianic anhydride crosslinking agent. While maintaining a high benzene ring content to preserve thermal stability, the crosslinking sites provide sites to inhibit charge migration, thereby improving high-temperature insulation performance.

[0008] To achieve the above objectives, the present invention employs the following solution: This invention provides a high-temperature dielectric film based on aromatic ring crosslinked polyetherimide. The high-temperature dielectric film based on aromatic ring crosslinked polyetherimide introduces benzohexacarboxylic acid trianic anhydride as an aromatic ring crosslinking agent between bisphenol A dianhydride and aromatic diamine, thereby constructing a covalent crosslinking network between the polyetherimide molecular chains.

[0009] Preferably, the content of phenylhexacarboxylic acid trianic anhydride is 5-20 mol of the molar amount of aromatic diamine.

[0010] More preferably, the content of phenylhexacarboxylic acid trianic anhydride is 5-15 mol of the molar amount of aromatic diamine.

[0011] The most preferred content is 10 mol of the molar amount of aromatic diamine.

[0012] Preferably, the bisphenol A dianhydride is one or more of bisphenol A type diether dianhydride, pyromellitic anhydride, or 4,4'-biphenyl ether dianhydride; and the aromatic diamine is one or more of m-phenylenediamine, p-phenylenediamine, and 3,3'-diaminodiphenylmethane.

[0013] Preferably, the high-temperature dielectric film has an optical band gap of 3.24-3.30 eV, a dielectric constant of 3-3.25 at 1000 Hz, and a dielectric loss of less than 5 × 10⁻⁶ at 200 °C. -3 .

[0014] Preferably, the high-temperature dielectric film exhibits a 30-60% higher breakdown strength at 150°C and 200°C compared to uncrosslinked polyetherimide.

[0015] Preferably, the 5% thermal weight loss temperature of the high-temperature dielectric film is higher than that of the uncrosslinked polyetherimide film, and the Young's modulus is increased by 10-45%.

[0016] The present invention also provides a method for preparing a high-temperature dielectric film based on aromatic ring crosslinked polyetherimide, comprising the following steps: (1) Dissolve bisphenol A dianhydride, aromatic diamine diether dianhydride and phenylhexacarboxylic acid trihydride in a polar organic solvent and stir mechanically to form a homogeneous solution; (2) Prepolymerization is carried out by film formation through casting or spin coating; (3) A high-temperature dielectric film based on aromatic ring crosslinked polyetherimide was obtained by heat treatment using a step heating method.

[0017] Preferably, in step (1), mechanical stirring is carried out at 90-110°C.

[0018] Preferably, in step (1), the polar organic solvent is one or more of N-methylpyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide.

[0019] Preferably, in step (1), the molar amounts of the aromatic diamine (m1), bisphenol A dianhydride (m2), and benzohexacarboxylic acid trihydride (m3) have the following quantitative relationship: 3 m3+2 m2=2 m1.

[0020] Preferably, in step (2), the prepolymerization is carried out at 100-120°C.

[0021] Preferably, in step (3), the stepped heating method includes four stages: 100℃, 150℃, 200℃ and 250℃, with each stage being kept at a temperature of 0.5-2 hours.

[0022] The present invention also provides the application of the above-mentioned high-temperature dielectric film based on aromatic ring crosslinked polyetherimide in the preparation of high-temperature film capacitors.

[0023] Preferably, high-temperature film capacitors are suitable for environments with operating temperatures above 150°C, including electric vehicle inverters, aerospace power systems, and renewable energy converters.

[0024] The advantages of this invention are: (1) Through aromatic ring crosslinking design, the thermal stability, mechanical strength and high temperature insulation performance of the film are synergistically improved; (2) The preparation process is simple and compatible with existing polymer processing technologies; (3) It maintains high energy density and low loss at high temperatures of 150-200℃ to meet the needs of extreme environment applications. Attached Figure Description

[0025] Figure 1 The infrared spectra of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown.

[0026] Figure 2 Thermogravimetric analysis (TGA) curves of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown.

[0027] Figure 3 The images show the UV-Vis spectra of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimides prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples.

[0028] Figure 4 The bar chart shows the mechanical tensile Young's modulus of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples.

[0029] Figure 5 The high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown in the room temperature dielectric spectrum diagrams.

[0030] Figure 6 The dielectric spectra at 200 °C are shown for the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples.

[0031] Figure 7 The breakdown field strength distribution at 150 °C is shown for the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example.

[0032] Figure 8 The breakdown field strength distribution at 200 °C is shown for the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example.

[0033] Figure 9 The graph shows the leakage current density at 200 °C as a function of electric field strength for the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example.

[0034] Figure 10 The diagram shows the energy storage performance of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example at 150 °C.

[0035] Figure 11 The graphs show the energy storage performance of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples at 200 °C.

[0036] Figure 12 This is a schematic diagram of the crosslinked portion structure in the high-temperature dielectric film based on aromatic ring crosslinked polyetherimide prepared according to the present invention. Detailed Implementation

[0037] Example 1: A mixture of 10 mol% m-phenylenediamine, phenylhexacarboxylic acid trianic anhydride, m-phenylenediamine, and bisphenol A type diether dianhydride (0.0142 g, 0.0508 g, and 0.2350 g, respectively) was dissolved in 10 mL of N-methylpyrrolidone. The solution was mechanically stirred at 90 °C to form a homogeneous solution. The solution was then cast into a film and prepolymerized at 100 °C. The film was subsequently heat-treated sequentially at 150 °C, 200 °C, and 250 °C, with each stage lasting 1 hour, to obtain a high-temperature dielectric film c-PEI based on aromatic ring crosslinked polyetherimide. 10mol% Ah .

[0038] High-temperature dielectric films c-PEI based on aromatic ring crosslinked polyetherimides 10mol% Ah The 5% weight thermal decomposition temperature of the film is 480℃, which is higher than that of the uncrosslinked polyetherimide film PEI prepared in the comparative example; the optical band gap is approximately 3.25 eV; the tensile strength is 2149 MPa, which is 43.7% higher than that of the uncrosslinked polyetherimide film PEI prepared in the comparative example; and the U... d90max The maximum discharge energy densities (with charge / discharge efficiency η greater than 90%) are 6.54 and 6.05 J / cm³, respectively. 3The PEI of the uncrosslinked polyetherimide film prepared in the comparative example was increased by 220% and 260%, respectively; the breakdown strength at 150℃ and 200℃ was 664 and 601 MV / m, respectively, which were 58% and 49.5% higher than the PEI of the uncrosslinked polyetherimide film prepared in the comparative example; and the dielectric loss at 200℃ was less than 5 × 10⁻⁶. -3 The dielectric constant is 3.23 (1000Hz).

[0039] Example 2: A mixture of 5 mol% m-phenylenediamine, phenylhexacarboxylic acid trianic anhydride, m-phenylenediamine, and bisphenol A type diether dianhydride (0.0074 g, 0.0526 g, and 0.2398 g, respectively) was dissolved in 10 mL of N-methylpyrrolidone. The solution was mechanically stirred at 90 °C to form a homogeneous solution. The solution was then cast into a film and prepolymerized at 100 °C. The film was subsequently heat-treated sequentially at 150 °C, 200 °C, and 250 °C, with each stage lasting 1 hour, to obtain a high-temperature dielectric film c-PEI based on aromatic ring crosslinked polyetherimide. 5mol% Ah .

[0040] High-temperature dielectric films c-PEI based on aromatic ring crosslinked polyetherimides 5mol% Ah The 5% weight thermal decomposition temperature is 476℃, which is higher than that of the uncrosslinked polyetherimide film PEI prepared in the comparative example; the optical band gap is approximately 3.30 eV; the tensile strength is 2025 MPa, which is 35.4% higher than that of the uncrosslinked polyetherimide film PEI prepared in the comparative example; and the U... d90max 5.18 J / cm 3 and 4.41 J / cm 3 The PEI of the uncrosslinked polyetherimide film prepared in the comparative example was increased by 152% and 162%, respectively; the breakdown strength at 150℃ and 200℃ was 605 and 557 MV / m, respectively, which were 44.0% and 38.5% higher than the PEI of the uncrosslinked polyetherimide film prepared in the comparative example; and the dielectric loss was less than 5×10⁻⁶. -3 The dielectric constant is 3.25 (1000Hz).

[0041] Example 3: A mixture of 20 mol% m-phenylenediamine, phenylhexacarboxylic acid trianic anhydride, m-phenylenediamine, and bisphenol A type diether dianhydride (0.0310 g, 0.0560 g, and 0.2130 g, respectively) was dissolved in 10 mL of N-methylpyrrolidone. The solution was mechanically stirred at 90 °C to form a homogeneous solution. After casting into a film, it was prepolymerized at 100 °C and then heat-treated sequentially at 150 °C, 200 °C, and 250 °C for 1 hour to obtain a high-temperature dielectric film c-PEI based on aromatic ring crosslinked polyetherimide. 20mol% Ah .

[0042] High-temperature dielectric films c-PEI based on aromatic ring crosslinked polyetherimides 20mol% Ah The 5% weight thermal decomposition temperature is 472℃, which is higher than that of the uncrosslinked polyetherimide film PEI prepared in the comparative example; the optical band gap is approximately 3.24 eV; the tensile strength is 1694 MPa, which is 13.3% higher than that of the uncrosslinked polyetherimide film PEI prepared in the comparative example; and the U... d90max The energy densities are 4.24 and 3.66 J / cm³. 3 The PEI of the uncrosslinked polyetherimide film prepared in the comparative example was increased by 112% and 115% respectively; the breakdown strength at 150℃ and 200℃ was 558 and 528 MV / m, respectively, which were 32.9% and 31.3% higher than the PEI of the uncrosslinked polyetherimide film prepared in the comparative example; and the dielectric loss was less than 1×10⁻⁶. -3 The dielectric constant is 3 (1000Hz).

[0043] Comparative example: m-phenylenediamine and bisphenol A type diether dianhydride (0.0516 g and 0.2484 g, respectively) were dissolved together in 10 mL of N-methylpyrrolidone and mechanically stirred at 90 °C to form a homogeneous solution. The solution was then cast into a film and prepolymerized at 100 °C. The film was then heat-treated sequentially at 150 °C, 200 °C, and 250 °C, with each stage held for 1 hour, to obtain an uncrosslinked polyetherimide film (PEI).

[0044] The optical band gap of uncrosslinked polyetherimide (PEI) film is approximately 3.33 eV; the Young's modulus is 1495 MPa; the U0 of uncrosslinked PEI film at 150 °C and 200 °C is... d90max The energy densities are 2.0 and 1.7 J / cm³, respectively. 3 The breakdown strength at 150℃ and 200℃ is 420 and 407 MV / s, respectively; the dielectric loss is less than 5 × 10⁻⁶. -3 The dielectric constant is 3.20 (1000Hz).

[0045] The following performance tests were performed on the high-temperature dielectric films based on aromatic ring crosslinked polyetherimides prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples: The 5% weight thermal decomposition temperature was tested using a TG thermogravimetric analyzer; dielectric properties were measured using an ALPHA-ANB device at a testing frequency of 10. 2 Hz-10 6 The chemical structure of the material was measured at Hz; the chemical structure was determined using a Fourier transform infrared spectrometer (Nicolet IS50) at wavenumbers of 500-3800 cm⁻¹. -1Within the range of tests; optical band gap was tested using an ultraviolet-visible-near-infrared spectrometer; Young's modulus was tested using a universal tensile tester; breakdown field strength was tested by applying DC current using a DCQ-20B-HSH high-voltage source; energy storage performance was tested using a PK-FERO20B (Poly K) meter; leakage current was tested using a Keithley 6514B ammeter.

[0046] Figure 1 The infrared spectra of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimides prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown.

[0047] Figure 1 The infrared spectra of the four films show that they possess the corresponding characteristic chemical functional groups of the basic polyetherimide films, indicating the successful synthesis of the characteristic structure of polyetherimide.

[0048] Figure 2 Thermogravimetric analysis (TGA) curves of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown.

[0049] Depend on Figure 2 It can be seen that the 5% weight thermal decomposition temperature of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 is higher than that of the uncrosslinked polyetherimide film PEI prepared in the comparative example.

[0050] Figure 3 The UV-Vis spectra of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimides prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown.

[0051] Depend on Figure 3 It can be seen that c-PEI 5mol% Ah (Example 2) has an optical bandgap of 3.24 eV and a c-PEI. 10mol% Ah (Example 1) has an optical bandgap of 3.25 eV and a c-PEI. 20mol% Ah The optical bandgap of (Example 3) is 3.30 eV, and the optical bandgap of PEI (Comparative Example 1) is 3.33 eV.

[0052] Figure 4 The bar charts showing the mechanical tensile Young's modulus of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimides prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown.

[0053] Depend on Figure 4It can be seen that the tensile strength of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 is significantly improved compared with that of the uncrosslinked polyetherimide film PEI, and the Young's modulus is increased by 10-45% compared with that of the uncrosslinked polyetherimide film PEI prepared in the comparative example.

[0054] Figure 5 The high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the room-temperature dielectric spectra of the polyetherimide films prepared in the comparative examples are shown.

[0055] Figure 6 The dielectric spectra of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative examples are shown at 200°C.

[0056] Depend on Figure 5 , 6 It can be seen that, compared with the uncrosslinked PEI film in the comparative example, the dielectric constant and loss tangent of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 remain at the same order of magnitude. Under the high temperature condition of 200℃, the change range of dielectric constant and loss tangent of the crosslinked film is significantly better than that of the uncrosslinked PEI film, indicating that the introduction of the aromatic ring crosslinking structure significantly improves the high-temperature dielectric stability of the material.

[0057] Figure 7 The breakdown field strength distribution of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example are shown at 150°C.

[0058] Figure 8 The breakdown field strength distribution at 200°C is shown for the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example.

[0059] Depend on Figure 7 , 8 It can be seen that the breakdown strength of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 at 150℃ and 200℃ is significantly improved compared with the PEI of the uncrosslinked polyetherimide film prepared in the comparative example.

[0060] Figure 9 The graphs show the leakage current density at 200°C as a function of electric field strength for the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example.

[0061] Depend on Figure 9It can be seen that the high-temperature dielectric films based on aromatic ring cross-linked polyetherimide prepared in Examples 1-3 and the uncross-linked polyetherimide film PEI prepared in the comparative example show a linear relationship between current density and electric field strength at 200℃ and 0-300MV / m, indicating that each film has good insulation performance. At the same time, the leakage current density of the high-temperature dielectric films based on aromatic ring cross-linked polyetherimide prepared in Examples 1-3 is lower than that of the cross-linked polyetherimide film PEI prepared in the comparative example, indicating that the high-temperature dielectric films based on aromatic ring cross-linked polyetherimide prepared in Examples 1-3 have better insulation performance.

[0062] Figure 10 The energy storage performance of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example at 150°C is shown.

[0063] Figure 11 The energy storage performance of the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 and the polyetherimide films prepared in the comparative example at 200 °C is shown.

[0064] Depend on Figure 10 , 11 It can be seen that the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 exhibit better performance at 150℃ and 200℃. d90max (Maximum discharge energy density with charge / discharge efficiency η greater than 90%) The energy density is significantly improved compared to the uncrosslinked polyetherimide film PEI prepared in the comparative example.

[0065] Depend on Figures 6-11 It can be seen that the high-temperature dielectric films based on aromatic ring crosslinked polyetherimide prepared in Examples 1-3 still maintain high energy density and low loss at high temperatures of 150-200℃.

[0066] Figure 12 A schematic diagram of the crosslinked portion structure in the high-temperature dielectric film based on aromatic ring crosslinked polyetherimide prepared according to the present invention is shown.

[0067] In summary, the present invention provides a method for preparing a high-temperature dielectric film based on aromatic ring crosslinked polyetherimide. Through aromatic ring crosslinking design, the thermal stability, mechanical strength, and high-temperature insulation properties of the film are synergistically improved. At the same time, the preparation process is simple and compatible with existing polymer processing technologies. The high-temperature dielectric film based on aromatic ring crosslinked polyetherimide provided by the present invention maintains high energy density and low loss at high temperatures of 150-200℃, meeting the requirements of extreme environment applications.

Claims

1. A high-temperature dielectric film based on aromatic ring crosslinked polyetherimide, characterized in that, The high-temperature dielectric film based on aromatic ring crosslinked polyetherimide introduces benzohexacarboxylic acid trianic anhydride as an aromatic ring crosslinking agent between bisphenol A dianhydride and aromatic diamine to construct a covalent crosslinking network between the polyetherimide molecular chains.

2. The high-temperature dielectric film based on aromatic ring crosslinked polyetherimide according to claim 1, characterized in that, The content of the benzohexacarboxylic acid trianic anhydride is 5-20 mol of the molar amount of aromatic diamine.

3. The high-temperature dielectric film based on aromatic ring crosslinked polyetherimide according to claim 1, characterized in that, The bisphenol A dianhydride is one or more of bisphenol A type diether dianhydride, pyromellitic anhydride, or 4,4'-biphenyl ether dianhydride; the aromatic diamine is one or more of m-phenylenediamine, p-phenylenediamine, and 3,3'-diaminodiphenylmethane.

4. The high-temperature dielectric film based on aromatic ring crosslinked polyetherimide according to claim 1, characterized in that, The high-temperature dielectric film has an optical band gap of 3.24-3.30 eV, a dielectric constant of 3-3.25 at 1000 Hz, and a dielectric loss of less than 5 × 10⁻⁶ at 200 ℃. -3 .

5. A method for preparing a high-temperature dielectric film based on aromatic ring crosslinked polyetherimide as described in any one of claims 1-4, comprising the following steps: (1) Dissolve bisphenol A dianhydride, aromatic diamine and benzohexacarboxylic acid trihydride in a polar organic solvent and stir mechanically to form a homogeneous solution; (2) Prepolymerization is carried out by film formation through casting or spin coating; (3) A high-temperature dielectric film based on aromatic ring crosslinked polyetherimide was obtained by heat treatment using a step heating method.

6. The preparation method according to claim 5, characterized in that, In step (1), the polar organic solvent is one or more of N-methylpyrrolidone, N,N-dimethylformamide or dimethyl sulfoxide.

7. The preparation method according to claim 5, characterized in that, In step (1), the molar amounts of the aromatic diamine (m1), bisphenol A dianhydride (m2), and benzohexacarboxylic acid trihydride (m3) have the following quantitative relationship: 3 m3+2 m2=2 m1.

8. The preparation method according to claim 5, characterized in that, In step (2), the prepolymerization is carried out at 100-120°C.

9. The preparation method according to claim 5, characterized in that, In step (3), the stepped heating method involves maintaining the temperature for 0.5-2 hours in each stage.

10. The application of a high-temperature dielectric film based on aromatic ring crosslinked polyetherimide as described in any one of claims 1-4 in the preparation of high-temperature film capacitors.

Images