Blended polyimide dielectric film as well as preparation method and application thereof
The dielectric film formed by blending benzimidazole semi-aromatic polyimide and polyetherimide solves the problem of easy breakdown of existing dielectric materials at high temperatures, and achieves excellent energy storage performance and breakdown strength at high temperatures, which is suitable for new energy technologies and national defense military equipment.
Patent Information
- Application Number
- CN202511513665.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-22
- Publication Date
- 2025-12-12
AI Technical Summary
Existing dielectric materials are prone to breakdown under high-temperature conditions, making it difficult to meet the high-temperature application requirements of new energy technologies such as new energy vehicles and national defense and military equipment.
A blended polyimide dielectric film is formed by combining benzimidazole semi-aromatic polyimide and polyetherimide. The young's modulus is improved and the conductivity loss is suppressed through the nanoscale "island-like" structure.
It maintains high energy storage performance at 200℃, with improved dielectric constant, enhanced breakdown strength, high glass transition temperature, and is easy to industrialize.
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Figure CN121108739A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of dielectric materials technology, and in particular to a blended polyimide dielectric film, its preparation method, and its application. Background Technology
[0002] Among numerous new energy technologies, dielectric capacitors have the advantage of high power density (~10). 8 With advantages such as high power density (W / kg), fast charging and discharging speed (<1μs), and long cycle life (~50,000 cycles), dielectric capacitors have broad prospects in national defense and military applications, such as high-power pulsed charging and discharging weapons, including electromagnetic railguns, laser guns, and catapult launch propulsion systems for shipborne aircraft. The booming development of emerging fields such as new energy vehicles has placed higher demands on the operating temperature of dielectric capacitors, requiring them to maintain high energy storage performance even at high temperatures up to 150℃.
[0003] However, biaxially oriented polypropylene (BOPP), the most widely used commercial dielectric material, is prone to breakdown failure at temperatures above 120°C, which limits its application in harsh environments. While heat-resistant polymers such as polyimide (PI) have high glass transition temperatures (…),… T g It can operate at temperatures above 150°C, but the charge injection, excitation, and transport generated under high temperature and high field conditions will increase conductivity loss, leading to a decrease in breakdown strength. E b The temperature will decrease significantly. Therefore, there is an urgent need to develop dielectric materials that can be used at higher temperatures. Summary of the Invention
[0004] This invention provides a blended polyimide dielectric film, its preparation method, and its application. The blended polyimide dielectric film provided by this invention has excellent high-temperature energy storage performance and can be used at 200°C.
[0005] The present invention provides a blended polyimide dielectric film comprising benzimidazole semi-aromatic polyimide and polyetherimide, wherein the mass ratio of benzimidazole semi-aromatic polyimide to polyetherimide is 1:0.25-4.
[0006] Optionally, the benzimidazole semi-aromatic polyimide is obtained by polymerization and imidization of a diamine containing a benzimidazole structure and an alicyclic dianhydride.
[0007] Optionally, the diamine containing the benzimidazole structure includes at least one of 2-(4-aminophenyl)-5-aminobenzimidazole, 6-amino-2-(4-amino-phenyl)-benzimidazole, 2,2'-bibenzimidazole-5,5'-diamine, and 2,2'-p-phenylenebis(5-aminobenzimidazole).
[0008] Optionally, the alicyclic dianhydride includes at least one of dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 4,5-cyclohexanetetracarboxylic dianhydride, and cyclobutanetetracarboxylic dianhydride.
[0009] Optionally, the molar ratio of the diamine containing the benzimidazole structure to the alicyclic dianhydride is 1:0.98-1.02.
[0010] Optionally, the polyetherimide is obtained by polymerization and imidization of a diamine monomer and a dianhydride monomer, wherein at least one of the diamine monomer and the dianhydride monomer contains an ether bond.
[0011] Optionally, the dianhydride monomer includes at least one of 1,3-phenylenediamine, 1,4-phenylenediamine, and 4,4'-diaminodiphenyl ether.
[0012] Optionally, the dianhydride monomer includes at least one of bisphenol A type diether dianhydride, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic anhydride, 4,4'-terephthalodioxydiphthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic anhydride.
[0013] Optionally, the molar ratio of the diamine monomer to the dianhydride monomer is 1:0.98-1.02.
[0014] Optionally, the thickness of the blended polyimide dielectric film is 8-15 µm.
[0015] The present invention also provides a method for preparing a blended polyimide dielectric film as described in any of the above technical solutions, comprising the following steps: A diamine containing a benzimidazole structure, an alicyclic dianhydride, and a first solvent are mixed to carry out a first polymerization reaction, yielding a benzimidazole semi-aromatic polyamic acid solution. The diamine monomer and dianhydride monomer used to prepare polyetherimide are mixed with a second solvent to carry out a second polymerization reaction, yielding a polyetheramic acid solution. A benzimidazole semi-aromatic polyamic acid solution and a polyether amic acid solution were mixed to obtain a blended solution. The blended solution was defoamed and then formed into a film, followed by an imidization reaction to obtain a blended polyimide dielectric film.
[0016] Optionally, the first solvent and the second solvent each independently comprise at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and resorcinol.
[0017] Optionally, the ratio of the total mass of the diamine containing the benzimidazole structure and the alicyclic dianhydride to the mass of the first solvent is 1:5-8.
[0018] Optionally, the ratio of the total mass of the diamine monomer and the dianhydride monomer to the mass of the second solvent is 1:5-8.
[0019] Optionally, the temperature of the first polymerization reaction and the second polymerization reaction are each independently 0-35°C, and the reaction time of the first polymerization reaction and the second polymerization reaction is each independently 35-45 h.
[0020] Optionally, the imidization reaction is carried out sequentially at 50-70℃ for 0.3-0.5 h, at 190-210℃ for 0.8-1 h, at 220-230℃ for 0.8-1 h, at 240-260℃ for 0.8-1 h, and at 270-280℃ for 0.8-1 h.
[0021] The present invention also provides the application of the blended polyimide dielectric film of any one of the above technical solutions and the blended polyimide dielectric film obtained by any one of the above technical solutions in dielectric capacitors.
[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a blended polyimide dielectric film comprising benzimidazole semi-aromatic polyimide and polyetherimide. In this dielectric film, the benzimidazole semi-aromatic polyimide forms a nanoscale "island-like" structure, providing a nano-confinement effect, significantly improving the Young's modulus of the blended polyimide dielectric film, suppressing conductivity loss, and thus improving high-temperature energy storage performance. Furthermore, this blended polyimide dielectric film also exhibits a high dielectric constant. According to the results of the embodiments, the blended polyimide dielectric film provided by this invention can achieve an energy storage density of 4.3-5.8 J / cm³ at 150°C and 90% efficiency. 3 The energy storage density can reach 3.3-4.5 J / cm³ at 200℃ and 90% efficiency. 3 Simultaneously, the dielectric constant increases from 2.78 for PEI to 3.56 at 200℃, the glass transition temperature reaches 255.4-318.2℃, and the breakdown strength at 200℃ reaches 576-593 kV / mm. It is evident that the blended polyimide dielectric film provided by this invention possesses excellent comprehensive properties.
[0023] Furthermore, the preparation method of the blended polyimide dielectric film provided by this invention is simple, easy to implement, compatible with the current industrial production process of polyimide films, and easy to industrialize. Attached Figure Description
[0024] The above and other objects, features, and advantages of the invention will be apparent from the following description of preferred embodiments illustrating the gist of the invention and its use, and the accompanying drawings, in which: Figure 1 A schematic diagram of the chemical structure of polyetherimide and benzimidazole semi-aromatic polyimide in the blended polyimide dielectric film obtained in Example 1 is shown.
[0025] Figure 2 The Fourier transform infrared spectra of the dielectric films obtained in Example 1 and Comparative Examples 1-2 are shown.
[0026] Figure 3 Differential scanning calorimetry curves of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 are shown.
[0027] Figure 4 The Young's modulus of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 is shown.
[0028] Figure 5 An atomic force microscope (AFM) image of the dielectric thin film obtained in Example 1 is shown.
[0029] Figure 6 The dielectric temperature spectra of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 are shown.
[0030] Figure 7 The breakdown strength test results of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 at 150°C are shown.
[0031] Figure 8 The breakdown strength test results of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 at 200°C are shown.
[0032] Figure 9 The results of energy storage performance tests of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 at 150°C are shown.
[0033] Figure 10 The results of energy storage performance tests of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 at 200°C are shown. Detailed Implementation
[0034] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the following embodiments, conditions and methods known in the art can be used for processing.
[0035] This invention provides a blended polyimide dielectric film comprising benzimidazole semi-aromatic polyimide and polyetherimide, wherein the mass ratio of benzimidazole semi-aromatic polyimide to polyetherimide is 1:0.25-4. The dielectric film provided by this invention is a blended polyimide dielectric film of benzimidazole semi-aromatic polyimide and polyetherimide. Due to the presence of NH in the imidazole ring of the benzimidazole semi-aromatic polyimide, it preferentially forms intermolecular hydrogen bonds in the benzimidazole semi-aromatic polyimide chain, further forming a nanoscale "island-like" structure in the blended polyimide dielectric film. This provides a nano-confinement effect, significantly improving the Young's modulus of the blended polyimide dielectric film, suppressing conductivity loss, and thus improving high-temperature energy storage performance.
[0036] In this invention, the mass ratio of the benzimidazole semi-aromatic polyimide to the polyetherimide is 1:0.25-4, specifically 1:0.25, 1:0.33, 1:1, 1:3, etc.
[0037] In some embodiments of the present invention, the benzimidazole semi-aromatic polyimide is obtained by polymerization and imidization of a diamine containing a benzimidazole structure and an alicyclic dianhydride.
[0038] In some embodiments of the present invention, the diamine containing the benzimidazole structure includes at least one of 2-(4-aminophenyl)-5-aminobenzimidazole, 6-amino-2-(4-aminophenyl)-benzimidazole, 2,2'-bibenzimidazole-5,5'-diamine, and 2,2'-p-phenylenebis(5-aminobenzimidazole).
[0039] In some embodiments of the present invention, the alicyclic dianhydride includes at least one selected from dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 4,5-cyclohexanetetracarboxylic dianhydride, and cyclobutanetetracarboxylic dianhydride.
[0040] In some embodiments of the present invention, the molar ratio of the diamine containing the benzimidazole structure to the alicyclic dianhydride is 1:0.98-1.02, specifically 1:0.98, 1:1, 1:1.02, etc.
[0041] In some embodiments of the present invention, the polyetherimide is obtained by polymerization and imidization of a diamine monomer and a dianhydride monomer, wherein at least one of the diamine monomer and the dianhydride monomer contains an ether bond.
[0042] In some embodiments of the present invention, the dianhydride monomer includes at least one selected from 1,3-phenylenediamine, 1,4-phenylenediamine, and 4,4'-diaminodiphenyl ether.
[0043] In some embodiments of the present invention, the dianhydride monomer includes at least one selected from bisphenol A type diether dianhydride, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 4,4'-terephthalodioxydiphthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride. In some embodiments of the present invention, the molar ratio of the diamine monomer to the dianhydride monomer is 1:0.98-1.02, specifically 1:0.98, 1:1, 1:1.02, etc.
[0044] In some embodiments of the present invention, the thickness of the blended polyimide dielectric film is 8-15 µm, specifically 8 µm, 10 µm, 12 µm, 15 µm, etc.
[0045] The present invention also provides a method for preparing a blended polyimide dielectric film as described in any of the above technical solutions, comprising the following steps: A diamine containing a benzimidazole structure, an alicyclic dianhydride, and a first solvent are mixed to carry out a first polymerization reaction, yielding a benzimidazole semi-aromatic polyamic acid solution. The diamine monomer and dianhydride monomer used to prepare polyetherimide are mixed with a second solvent to carry out a second polymerization reaction, yielding a polyetheramic acid solution. A benzimidazole semi-aromatic polyamic acid solution and a polyether amic acid solution were mixed to obtain a blended solution. The blended solution was defoamed and then formed into a film, followed by an imidization reaction to obtain a blended polyimide dielectric film.
[0046] In this invention, a polyamic acid solution and a polyetheramic acid solution are first prepared, then the two are mixed and subjected to an imidization reaction to directly obtain a blended polyimide dielectric film. The process is simple and easy to implement.
[0047] This invention first involves mixing a diamine containing a benzimidazole structure, an alicyclic dianhydride, and a first solvent to undergo a first polymerization reaction, yielding a benzimidazole semi-aromatic polyamic acid solution. Then, the diamine monomer and dianhydride monomer used to prepare polyetherimide are mixed with a second solvent to undergo a second polymerization reaction, yielding a polyetheramic acid solution. Through the first and second polymerization reactions, both a viscous benzimidazole semi-aromatic polyamic acid solution and a polyetheramic acid solution can be obtained.
[0048] In some embodiments of the present invention, the first solvent and the second solvent each independently comprise at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and resorcinol.
[0049] In some embodiments of the present invention, the total mass ratio of the diamine containing the benzimidazole structure and the alicyclic dianhydride to the mass of the first solvent is 1:5-8, specifically 1:5, 1:5.8, 1:6, 1:7, or 1:8.
[0050] In some embodiments of the present invention, the ratio of the total mass of the diamine monomer and the dianhydride monomer to the mass of the second solvent is 1:5-8, specifically 1:5, 1:6, 1:6.7, 1:7, or 1:8.
[0051] In some embodiments of the present invention, the temperatures of the first polymerization reaction and the second polymerization reaction are each independently 0-35°C, specifically 10°C, 20°C, 25°C, 30°C, 35°C, etc.; the reaction times of the first polymerization reaction and the second polymerization reaction are each independently 35-45 h, specifically 35 h, 38 h, 40 h, 43 h, 45 h, etc. In the present invention, the above conditions are conducive to the complete reaction of the monomers.
[0052] After obtaining benzimidazole semi-aromatic polyamic acid solution and polyetheramic acid solution, the present invention mixes the benzimidazole semi-aromatic polyamic acid solution and the polyetheramic acid solution to obtain a blended solution.
[0053] The present invention does not have any particular limitation on the mixing method of benzimidazole semi-aromatic polyamic acid solution and polyetheramic acid solution; they can be mixed according to the required ratio.
[0054] In this invention, the ratio of the benzimidazole semi-aromatic polyamic acid solution and the polyetheramic acid solution is calculated and mixed according to the mass ratio of benzimidazole semi-aromatic polyimide to polyetherimide in the target product. In the preparation of polyimide, the ratio of diamine to dianhydride used is approximately 1:1. It is generally assumed that all diamine and dianhydride participate in the reaction; therefore, the total mass of diamine and dianhydride is considered the mass of polyimide. In this embodiment, the required mass of benzimidazole semi-aromatic polyamic acid solution and polyetheramic acid solution is calculated based on the mass ratio of the target product, and then they are mixed.
[0055] After obtaining the blended solution, the present invention defoams the blended solution and forms a film, and then performs an imidization reaction to obtain a blended polyimide dielectric film.
[0056] The present invention does not have any particular limitation on the defoaming (i.e., degassing) and film formation methods. Conventional liquid defoaming (such as vacuum defoaming) and film formation methods (such as coating on a substrate) can be used.
[0057] In some embodiments of the present invention, the iminolation reaction is carried out sequentially at 50-70℃ (specifically, 50℃, 60℃, 70℃, etc.) for 0.3-0.5 h (specifically, 0.3 h, 0.4 h, 0.5 h, etc.), at 190-210℃ (specifically, 190℃, 200℃, 210℃, etc.) for 0.8-1 h (specifically, 0.8 h, 0.9 h, 1 h, etc.), at 220-230℃ (specifically, 220℃, 225℃, 230℃, etc.) for 0.8-1 h (specifically, 0.8 h, 0.9 h, 1 h, etc.), and at 240-260℃ (specifically, 240℃, 250℃, 260℃, etc.) for 0.8-1 h (specifically, 0.8 h, 0.9 h, 1 h, etc.). The imidization reaction involves holding the resulting liquid film at 270-280℃ (specifically 270℃, 275℃, 280℃, etc.) for 0.8-1 h (specifically 0.8 h, 0.9 h, 1 h, etc.), preferably at 70℃ for 0.5 h, 200℃ for 1 h, 225℃ for 1 h, 250℃ for 1 h, and 275℃ for 1 h. In this embodiment, the imidization reaction involves directly placing the resulting liquid film at 50-70℃ for the first holding stage, and then sequentially raising the temperature to the temperature of each holding stage for holding. The heating rate from the end of each holding stage to the next holding stage is 10℃ / min. In this invention, the above imidization reaction conditions allow for precise control of reaction kinetics, ensuring the stable and complete conversion of the polyamic acid precursor into high-performance polyimide.
[0058] In some embodiments of the present invention, after the imidization reaction is completed to obtain the blended polyimide dielectric film, the blended polyimide dielectric film is naturally cooled to room temperature and then peeled off from the substrate for application. The present invention does not have a special limitation on the peeling method, and a conventional peeling method can be used, such as peeling by soaking in warm water, and then drying before application.
[0059] The present invention also provides the application of the blended polyimide dielectric film of any one of the above technical solutions or the blended polyimide dielectric film obtained by any one of the above technical solutions in dielectric capacitors, especially in dielectric capacitors in high temperature (150-200℃, specifically 150℃, 200℃, etc.) application environments.
[0060] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0061] Example 1 0.7 mmol (0.1570 g) of 2-(4-aminophenyl)-5-aminobenzimidazole and 0.7 mmol (0.2144 g) of dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride were added to 2.1 mL (2.17 g) of N-methylpyrrolidone, stirred and dissolved at 25 °C, and the reaction was continued for 40 h to obtain a benzimidazole semi-aromatic polyamic acid solution.
[0062] 0.7 mmol (0.3643 g) of bisphenol A diether dianhydride and 0.7 mmol (0.0757 g) of 1,3-phenylenediamine were added to 2.8 mL (2.94 g) of N-methylpyrrolidone, stirred and dissolved at 25 °C, and the reaction was continued for 40 h to obtain a polyether ammonium acid solution.
[0063] A benzimidazole semi-aromatic polyamic acid solution and a polyetheramic acid solution were mixed in a 1:1 mass ratio of benzimidazole semi-aromatic polyimide to polyetherimide to obtain a blend solution.
[0064] The blend solution was degassed under vacuum, then coated onto a glass plate using a doctor blade. Imidification was then carried out sequentially at 70℃ for 0.5 h, 200℃ for 1 h, 225℃ for 1 h, 250℃ for 1 h, and 275℃ for 1 h. After each temperature holding period, the temperature was increased to the next temperature at a rate of 10℃ / min. A 12 μm thick blended polyimide dielectric film was obtained on the glass plate, denoted as 50% SPBII ( Figure 1 The diagram shows the chemical structure of polyetherimide and benzimidazole semi-aromatic polyimide in the blended polyimide dielectric film obtained in this embodiment.
[0065] Example 2 The blended polyimide dielectric film was prepared according to the method of Example 1, except that the benzimidazole semi-aromatic polyamic acid solution and the polyetheramic acid solution were mixed in a mass ratio of benzimidazole semi-aromatic polyimide to polyetherimide of 1:3. The resulting blended polyimide dielectric film was denoted as 25%SPBII.
[0066] Example 3 The blended polyimide dielectric film was prepared according to the method of Example 1, except that the benzimidazole semi-aromatic polyamic acid solution and the polyetheramic acid solution were mixed in a mass ratio of benzimidazole semi-aromatic polyimide to polyetherimide of 3:1. The resulting blended polyimide dielectric film was denoted as 75%SPBII.
[0067] Comparative Example 1 A benzimidazole semi-aromatic polyamic acid solution was prepared according to the method in Example 1. Then, the benzimidazole semi-aromatic polyamic acid solution was subjected to defoaming, film formation and imidization reaction as in Example 1 to obtain a benzimidazole semi-aromatic polyimide dielectric film, denoted as SPBII.
[0068] Comparative Example 2 A polyether ammonium acid solution was prepared according to the method in Example 1. Then, the polyether ammonium acid solution was subjected to defoaming, film formation and imidization reaction as in Example 1 to obtain a polyetherimide dielectric film, denoted as PEI.
[0069] To test the performance of the films obtained in the above embodiments and comparative examples, after the imidization reaction was completed, the glass plate loaded with the film was naturally cooled to room temperature, then immersed in warm water, the resulting film was peeled off, and then dried at 80°C to obtain an independent polyimide dielectric film.
[0070] The Fourier transform infrared spectra of the dielectric films obtained in Example 1 and Comparative Examples 1-2 were tested, and the results are as follows: Figure 2 As shown. By Figure 2 It can be seen that at 1350 cm -1 1776 cm -1 and 1715 cm -1 The peaks at 1303 cm⁻¹ correspond to C-N stretching, symmetric stretching, and asymmetric C=O stretching of the imide ring, respectively. -1 The peak at that location corresponds to the characteristic peak of the imidazole ring, indicating that a blended polyimide dielectric film was obtained.
[0071] Differential scanning calorimetry (DSC) curves of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 were tested, and the results are as follows: Figure 3 As shown. By Figure 3 It can be concluded that the glass transition temperature of the dielectric film obtained in Example 1 is 287.5℃, the glass transition temperature of the dielectric film obtained in Example 2 is 255.4℃, and the glass transition temperature of the dielectric film obtained in Example 3 is 318.2℃, indicating that the blended polyimide dielectric films provided by the present invention all have high glass transition temperatures.
[0072] The Young's modulus of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 was tested, and the results are as follows: Figure 4 As shown. By Figure 4 As can be seen, the Young's moduli of the dielectric films obtained in Examples 1-3 are 5.32 GPa, 4.71 GPa and 5.38 GPa, respectively, which are high.
[0073] The atomic force microscopy image of the dielectric thin film obtained in Example 1 is shown below. Figure 5 As shown. In Figure 5Materials with high Young's modulus exhibit a bright color. As previously shown by Young's modulus testing, SPBII is a high modulus material. Figure 5 The bright yellow color is SPBII, which shows that benzimidazole semi-aromatic polyimide exhibits an "island" structure in polyetherimide.
[0074] The dielectric temperature spectra of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 were tested, and the results are as follows: Figure 6 As shown. By Figure 6 It can be seen that the dielectric constant of the dielectric film obtained in Example 1 is 3.70 at room temperature (35°C), which is higher than that of the commercial dielectric film PEI (3.07). However, under high temperature (200°C) conditions, the dielectric constant decreases to 3.36, but is still higher than that of PEI. Similarly, the dielectric constants of Examples 2 and 3 at both room temperature and high temperature are also higher than that of PEI, and the difference in dielectric loss between them is small. This indicates that the blended polyimide dielectric film provided by the present invention improves the dielectric constant while maintaining low dielectric loss.
[0075] The breakdown properties of the dielectric films obtained in Examples 1-3 and Comparative Examples 1-2 were tested at 150°C and 200°C, and the results are as follows: Figure 7 and Figure 8 As shown. By Figure 7 and Figure 8 It can be seen that the dielectric film obtained in Example 1 has a breakdown strength of 632 kV / mm and 593 kV / mm at 150℃ and 200℃, respectively; the dielectric film obtained in Example 2 has a breakdown strength of 623 kV / mm and 584 kV / mm at 150℃ and 200℃, respectively; the dielectric film obtained in Example 3 has a breakdown strength of 599 kV / mm and 576 kV / mm at 150℃ and 200℃, respectively; the dielectric film obtained in Comparative Example 1 has a breakdown strength of 569 kV / mm and 529 kV / mm at 150℃ and 200℃, respectively; and the dielectric film obtained in Comparative Example 2 has a breakdown strength of 555 kV / mm and 516 kV / mm at 150℃ and 200℃, respectively. It is evident that the breakdown strength of the blended polyimide dielectric film provided by this invention is higher than that of Comparative Examples 1 and 2, indicating that blending the two polyimides improves the insulation performance of the dielectric material.
[0076] The energy storage performance of the dielectric films obtained in Example 1 and Comparative Examples 1-2 at 150°C and 200°C was tested, and the results are as follows: Figure 9 and 10 As shown. By Figure 7 and 8 It can be seen that the dielectric film obtained in Example 1 achieves an energy storage density of 5.8 J / cm³ at 150°C and 90% efficiency. 3 At 200℃ and 90% efficiency, the energy storage density reaches 4.5 J / cm³.3 The dielectric film obtained in Example 2 has a storage density of 4.28 J / cm³ at 150°C and 90% efficiency. 3 The energy storage density at 200℃ and 90% efficiency is 3.33 J / cm³. 3 The dielectric film obtained in Example 3 has a storage density of 5.46 J / cm³ at 150°C and 90% efficiency. 3 The energy storage density at 200℃ and 90% efficiency is 4.01 J / cm³. 3 The dielectric film obtained in Comparative Example 1 has a storage density of 4.19 J / cm³ at 150 °C and 90% efficiency. 3 The energy storage density at 200℃ and 90% efficiency is 2.56 J / cm³. 3 The dielectric film obtained in Comparative Example 2 has a storage density of 2.20 J / cm³ at 150℃ and 90% efficiency. 3 The energy storage density at 200℃ and 90% efficiency is 1.71 J / cm³. 3 It can be seen that the high-temperature energy storage performance of the blended polyimide dielectric film provided by the present invention is higher than that of comparative examples 1 and 2, indicating that the blending of the two polyimides produces a synergistic effect.
[0077] Although preferred embodiments of the invention have been shown and described, it is conceivable that those skilled in the art can devise various modifications to the invention within the spirit and scope of the appended claims.
Claims
1. A blended polyimide dielectric film comprising benzimidazole semi-aromatic polyimide and polyetherimide, wherein the mass ratio of benzimidazole semi-aromatic polyimide to polyetherimide is 1:0.25-4.
2. The blended polyimide dielectric film according to claim 1, characterized in that, The benzimidazole semi-aromatic polyimide is obtained by polymerization and imidization of a diamine containing a benzimidazole structure and an alicyclic dianhydride.
3. The blended polyimide dielectric film according to claim 2, characterized in that, The diamine containing the benzimidazole structure includes at least one of 2-(4-aminophenyl)-5-aminobenzimidazole, 6-amino-2-(4-amino-phenyl)-benzimidazole, 2,2'-bibenzimidazole-5,5'-diamine, and 2,2'-p-phenylenebis(5-aminobenzimidazole). The alicyclic dianhydride includes at least one selected from dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 4,5-cyclohexanetetracarboxylic dianhydride, and cyclobutanetetracarboxylic dianhydride. The molar ratio of the diamine containing the benzimidazole structure to the alicyclic dianhydride is 1:0.98-1.
02.
4. The blended polyimide dielectric film according to claim 1, characterized in that, The polyetherimide is obtained by polymerization and imidization of a diamine monomer and a dianhydride monomer, wherein at least one of the diamine monomer and the dianhydride monomer contains an ether bond.
5. The blended polyimide dielectric film according to claim 4, characterized in that, The dianhydride monomer includes at least one selected from 1,3-phenylenediamine, 1,4-phenylenediamine, and 4,4'-diaminodiphenyl ether. The dianhydride monomer includes at least one selected from bisphenol A type diether dianhydride, 4,4'-(hexafluoroisopropylidene) phthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 4,4'-terephthalodioxydiphthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride. The molar ratio of the diamine monomer to the dianhydride monomer is 1:0.98-1.
02.
6. The blended polyimide dielectric film according to any one of claims 1-5, characterized in that, The thickness of the blended polyimide dielectric film is 8-15 µm.
7. A method for preparing a blended polyimide dielectric film according to any one of claims 1-6, comprising the following steps: A diamine containing a benzimidazole structure, an alicyclic dianhydride, and a first solvent are mixed to carry out a first polymerization reaction, yielding a benzimidazole semi-aromatic polyamic acid solution. The diamine monomer and dianhydride monomer used to prepare polyetherimide are mixed with a second solvent to carry out a second polymerization reaction, yielding a polyetheramic acid solution. A benzimidazole semi-aromatic polyamic acid solution and a polyether amic acid solution were mixed to obtain a blended solution. The blended solution was defoamed and then formed into a film, followed by an imidization reaction to obtain a blended polyimide dielectric film.
8. The preparation method according to claim 7, characterized in that, The first solvent and the second solvent each independently comprise at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and resorcinol. The total mass ratio of the diamine containing the benzimidazole structure and the alicyclic dianhydride to the mass of the first solvent is 1:5-8. The total mass ratio of the diamine monomer and the dianhydride monomer to the mass of the second solvent is 1:5-8. The temperatures of the first polymerization reaction and the second polymerization reaction are each independently 0-35°C, and the reaction times of the first polymerization reaction and the second polymerization reaction are each independently 35-45 h.
9. The preparation method according to claim 7 or 8, characterized in that, The imidization reaction was carried out sequentially at 50-70℃ for 0.3-0.5 h, at 190-210℃ for 0.8-1 h, at 220-230℃ for 0.8-1 h, at 240-260℃ for 0.8-1 h, and at 270-280℃ for 0.8-1 h.
10. The application of the blended polyimide dielectric film according to any one of claims 1-6 and the blended polyimide dielectric film obtained by the preparation method according to any one of claims 7-9 in dielectric capacitors.