Polybenzimidazole / polyetherimide composite film dielectric as well as preparation method and application thereof

Abstract

The invention discloses a polybenzimidazole / polyetherimide composite film dielectric and a preparation method and application thereof.The method comprises the steps that N-methyl-2-pyrrolidone, 4, 4-diaminodiphenyl ether, 1, 2, 4, 5-phenylenetetramine tetrahydrochloride, 1, 3-benzenetricarboxaldehyde and bisphenol A dianhydride serve as raw materials, polybenzimidazole is generated while polyetherimide is generated, and the polybenzimidazole / polyetherimide composite film dielectric is obtained; and the polybenzimidazole and the polyetherimide are synchronously cross-linked to prepare the polybenzimidazole / polyetherimide composite film dielectric medium. According to the preparation method disclosed by the invention, through an improved polyetherimide preparation process which is mild in condition, simple to operate and easy for large-scale production, the obtained composite film dielectric medium is applied to an energy storage battery and has dielectric properties such as higher energy storage density and higher breakdown strength.

Description

Technical Field

[0001] The invention belongs to the technical field of dielectric energy storage material development, and relates to a polybenzimidazole / polyetherimide composite film dielectric and a preparation method and application thereof. Background Art

[0002] With the development of advanced electronic and electrical systems, it is urgent to improve the performance of energy storage devices in high temperature environments. Film capacitors have the advantages of high power density, fast energy release rate, high normal operating temperature, etc., and are widely used in high-power pulse power supplies such as motor drives, mobile power systems, and spacecraft power supplies. Therefore, it is of great significance to develop new dielectric materials with high energy storage density and high charge and discharge efficiency and expand their operating temperature range (25-250°C).

[0003] Dielectric materials are divided into two categories: organic polymers and inorganic ceramics. Polymer dielectrics store and release energy through local dipole cyclization, achieve rapid charging and discharging, and have high breakdown field strength (E b ), low dielectric loss, good flexibility and other advantages. However, existing polymer dielectric materials, such as biaxially oriented polypropylene film (BOPP), polycarbonate (PC), polyimide (PI), fluorene polyester (FPE) and polyether ether ketone (PEEK), have problems such as low dielectric constant and significant degradation of breakdown field strength under high temperature conditions (>100°C). The glass transition temperature (T) of polyetherimide (PEI) is about 100°C. g ) is about 217℃, with a high dielectric constant (ε r =3.2), low dielectric loss (0.29%), flexibility, and processability. Under high temperature conditions, PEI can still maintain a moderate dielectric constant and low dielectric loss, and is considered to be the next generation of high-performance capacitor dielectric materials. In recent years, a large number of studies have been devoted to improving the energy storage density and charge and discharge efficiency of polymer dielectrics under high temperature conditions. Doping inorganic nanofillers (Al2O3, HfO2, BaTiO3, BNNS, etc.) in polymer dielectrics improves their performance in high temperature environments. However, polymer dielectrics doped with inorganic nanofillers require a large amount of doping to achieve a significant increase in the dielectric constant. This method has a complex preparation process, which reduces the flexibility, uniformity and processability of polymer-based composite materials, resulting in a decrease in mechanical properties and an increase in the cost of large-scale thin film production. At the same time, a large amount of doped inorganic nanoparticles produce a dielectric mismatch effect at the interface with the organic polymer, which reduces the breakdown field strength. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a polybenzimidazole / polyetherimide composite thin film dielectric and a preparation method and application thereof, thereby solving the technical problems in the prior art that when the inorganic nanofiller is doped in a large amount in the polymer dielectric, the flexibility, uniformity and processability of the polymer are reduced, and the dielectric mismatch effect at the interface between the inorganic nanoparticles and the organic polymer reduces the breakdown field strength.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric comprises the following steps:

[0007] S1: N-methyl-2-pyrrolidone, 4,4-diaminodiphenyl ether, 1,2,4,5-benzenetetramine tetrahydrochloride and trimesic acid aldehyde are mixed and ultrasonically dispersed to obtain a uniform mixed solution;

[0008] S2: adding bisphenol A dianhydride to the mixed solution, and stirring the mixture in an ice-water bath under the protection of an inert atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid;

[0009] S3: using the polybenzimidazole / polyetheramic acid composite colloid to prepare a polybenzimidazole / polyetheramic acid composite film;

[0010] S4: performing imidization treatment on the polybenzimidazole / polyetheramic acid composite film to obtain the polybenzimidazole / polyetherimide composite film dielectric.

[0011] Preferably, the mass ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is 1:(2.4-2.8); the mass ratio of 4,4-diaminodiphenyl ether to bisphenol A dianhydride is 1:(2.5-2.8).

[0012] Preferably, the ratio of the total mass of trimesaldehyde and 1,2,4,5-benzenetetraamine tetrahydrochloride to the total mass of 4,4-diaminodiphenyl ether and bisphenol A dianhydride is (0.1-0.5):100.

[0013] Preferably, in step S2, the bisphenol A dianhydride is added to the mixed solution in batches.

[0014] Preferably, in step S3, before using the polybenzimidazole / polyetheramic acid composite colloid to prepare the polybenzimidazole / polyetheramic acid composite film, the polybenzimidazole / polyetheramic acid composite colloid is subjected to vacuum treatment at room temperature.

[0015] Preferably, in step S3, the thickness of the polybenzimidazole / polyether amic acid composite film is 8 to 15 μm.

[0016] Preferably, in step S4, the imidization treatment process is specifically as follows: the heating rate is 1.5-2°C / min, and the gradient heating treatment is performed in the range of 100-300°C.

[0017] A polybenzimidazole / polyetherimide composite film dielectric is prepared by the method.

[0018] Preferably, in the composite thin film dielectric, the mass ratio of polybenzimidazole to polyetherimide is (0.1-0.5):100.

[0019] The above-mentioned polybenzimidazole / polyetherimide composite film dielectric is used in polymer-based film capacitors.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] The invention discloses a preparation method of a polybenzimidazole / polyetherimide composite thin film dielectric. In the method, firstly, the introduction of a polybenzimidazole connecting polymer improves the energy storage performance of the film while enhancing its stability at high temperature; secondly, both polybenzimidazole (PBI) and polyetherimide (PEI) molecules are chain structures, and both polybenzimidazole and polyetherimide molecules contain cyclic π bonds, which are closely arranged and combined through π-π conjugation. In addition, the polybenzimidazole molecule contains C=O, and the polyetherimide molecule contains C=N, and C=O and C=N can be Cumulative double bonds are formed through conjugation, that is, amino cross-linked regions are formed. The two conjugated effects effectively reduce the free volume, reduce structural defects, significantly enhance the molecular interaction force between the chains of the composite material, greatly improve the breakdown field strength of the polymer, and at the same time inhibit dielectric loss, improve the polarization strength of the composite material and avoid the electric field distortion caused by the mismatch of dielectric constant and conductivity between the filler and the matrix; finally, due to the existence of the two conjugated effects, the tensile strength and modulus of the composite material are improved, giving the polybenzimidazole / polyetherimide dielectric film excellent mechanical processing properties.

[0022] Furthermore, the mass ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is 1:(2.4-2.8). First, the appropriate mass ratio can ensure that the reactants are fully in contact in the solution, thereby accelerating the rate of the polymerization reaction. Too high or too low a ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride may affect the reaction rate, resulting in incomplete reaction or the production of by-products; a reasonable mass ratio helps to generate polybenzimidazole segments with uniform structure and stable performance, which is crucial for the subsequent compounding with polyetheramic acid and the performance of the final film. Secondly, the ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride directly affects the length and crosslinking degree of the PBI segment, and then affects the mechanical properties of the composite film. The appropriate mass ratio can optimize the mechanical indicators of the film such as tensile strength and modulus; the stability of the PBI segment has an important influence on the thermal stability of the composite film. A reasonable mass ratio can ensure that the PBI segment can still maintain a stable structure at high temperatures, thereby improving the thermal stability of the film. Finally, the appropriate mass ratio can make the composite colloid easier to flow and spread during processing, thereby improving the film-forming property and surface smoothness of the film. In addition, the appropriate mass ratio can reduce unnecessary side reactions and make the polymerization reaction more controllable, thereby obtaining a purer polymerization product. In summary, the mass ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is set to 1:(2.4-2.8) based on a comprehensive consideration of factors such as polymerization reaction efficiency, product quality, film properties, processing properties, and reaction controllability. This setting is helpful for the preparation of polybenzimidazole / polyetherimide composite film dielectrics with excellent performance.

[0023] The mass ratio of 4,4-diaminodiphenyl ether (ODA) to bisphenol A dianhydride (BPADA) is 1: (2.5-2.8). First, the appropriate mass ratio can ensure that ODA and BPADA participate in the reaction in a manner close to the stoichiometric ratio in the reaction system, thereby accelerating the rate of the polymerization reaction and making the reaction more complete; a reasonable mass ratio helps to reduce the unreacted raw material residues and the generation of by-products, and improve the purity and uniformity of the product. Secondly, the mass ratio of ODA to BPADA directly affects the length and cross-linking degree of the generated polyetherimide (PEI) segment. The appropriate mass ratio can optimize the structure of the PEI segment, making it have better thermal stability, mechanical properties and electrical properties; the thermal stability of the PEI segment has an important influence on the overall performance of the composite film. A reasonable mass ratio can ensure that the PEI segment can still maintain a stable structure at high temperatures, thereby improving the thermal stability of the film. Thirdly, the mass ratio of ODA to BPADA also affects the mechanical properties of the composite film, such as tensile strength, modulus and toughness. The appropriate mass ratio can optimize these mechanical indicators and make the film have better tensile, bending and tearing resistance; the interaction between the PEI segment and the PBI segment also affects the electrical properties of the composite film; a reasonable mass ratio can optimize the electrical indicators of the film, such as dielectric constant, dielectric loss and breakdown field strength. Finally, an appropriate mass ratio can reduce unnecessary side reactions and make the polymerization reaction more controllable, thereby obtaining a purer polymerization product; a reasonable mass ratio helps to increase the yield of the polymerization reaction and reduce the waste of raw materials. In summary, the mass ratio of 4,4-diaminodiphenyl ether to bisphenol A dianhydride is set to 1: (2.5-2.8) based on a comprehensive consideration of factors such as polymerization efficiency, product quality, polyetherimide segment performance, composite film performance, processing performance and reaction controllability. This setting helps to prepare polybenzimidazole / polyetherimide composite film dielectrics with excellent performance.

[0024] Furthermore, the ratio of the total mass of the trimesaldehyde and 1,2,4,5-benzenetetramine tetrahydrochloride to the total mass of 4,4-diaminodiphenyl ether and bisphenol A dianhydride is (0.1-0.5):100. First, the ratio setting allows the relative content of polybenzimidazole (PBI) and polyetherimide (PEI) in the composite film to be finely regulated. The introduction of PBI can improve the energy storage performance of the film at high temperature, and the appropriate ratio can ensure that this advantage is fully utilized. The addition of PEI can significantly improve the mechanical properties of the composite film, such as tensile strength, modulus and toughness. By adjusting the ratio of the two raw materials, these mechanical indicators can be further optimized. By adjusting this ratio, it can be ensured that the two polymers work synergistically in the composite film to achieve the best balance in performance. At the same time, due to the strong conjugated bonds between the two polymers, the performance requirements of use can be achieved by introducing a small amount of polybenzimidazole, and the impact on the polyetherimide body is small.

[0025] Further, in step S2, the bisphenol A dianhydride is added to the mixed solution in batches. First, the reaction of bisphenol A dianhydride and 4,4-diaminodiphenyl ether is an exothermic process. Adding BPADA in batches can gradually release the reaction heat, avoid adding it all at once and causing the local temperature to be too high, thereby controlling the reaction rate within an appropriate range, reducing the occurrence of side reactions, and improving the purity and quality of the product; gradually adding BPADA can ensure that the reactants are more evenly distributed in the mixed solution, making the reaction more uniform, which is conducive to the generation of polymers with uniform structure and stable performance. Secondly, in the process of adding BPADA in batches, the mixed solution can be continuously stirred so that the newly added BPADA is quickly dispersed and fully contacted with the reactants, promoting uniform mixing of the solution, and a good solution mixing state is conducive to full contact and collision between the reactants, thereby improving the reaction efficiency and reducing the reaction time.

[0026] Further, in step S3, before using the polybenzimidazole / polyetheramic acid composite colloid to prepare the polybenzimidazole / polyetheramic acid composite film, the polybenzimidazole / polyetheramic acid composite colloid is subjected to vacuum treatment at room temperature. The vacuum treatment can effectively remove the bubbles in the film to obtain a dense and defect-free polybenzimidazole / polyetherimide composite film. First, the presence of bubbles is an important defect in the film quality. They will cause the mechanical properties of the film to decrease, such as tensile strength, bending strength, etc., and the number of defects in the film can be significantly reduced by removing the bubbles through vacuum treatment, thereby improving the overall quality of the film. Secondly, the bubbles will also affect the flatness of the film, making the surface of the film uneven. Removing bubbles through vacuum treatment can make the surface of the film smoother, which is beneficial for subsequent processing and use; the presence of bubbles will also cause problems such as breakage or damage of the film during subsequent processing, thereby reducing the yield rate. Removing bubbles through vacuum treatment can improve the processing stability and yield rate of the film; bubbles will also cause the film to be eroded by the external environment during use and accelerate aging. After removing the bubbles, the durability of the film will be improved, thereby extending its service life.

[0027] Furthermore, in step S3, the thickness of the polybenzimidazole / polyetheramic acid composite film is 8 to 15 μm. First, within this thickness range, the film can usually exhibit good mechanical properties, such as high tensile strength, modulus and toughness; the appropriate thickness helps to optimize the electrical properties of the film, such as dielectric constant, dielectric loss and breakdown field strength. Secondly, the thinner thickness makes it easier to achieve uniform distribution of the film during the coating process, reducing the performance differences caused by uneven thickness; when preparing the composite film, the thinner thickness is conducive to the close fitting of the laminated materials, improving the lamination effect, thereby enhancing the overall performance of the film. In addition, with the rapid development of flexible electronic technology, the demand for film materials is increasing. The thickness of 8 to 15 μm makes the polybenzimidazole / polyetheramic acid composite film have broad application prospects in flexible electronic fields such as flexible displays and wearable devices. At the same time, the appropriate thickness setting can keep its stable performance in high temperature environments.

[0028] Further, in step S4, the imidization treatment process is specifically as follows: the heating rate is 1.5-2°C / min, and the gradient heating treatment is performed in the range of 100-300°C. First, the gradient heating method makes the temperature rise gradually, avoiding the rapid change of temperature, which helps to control the rate of imidization reaction and prevent side reactions or uneven product structure caused by too fast reaction; through gradient heating, it can ensure that the temperature distribution of the film is more uniform during the entire heating process, which is conducive to the uniform reaction and the uniformity of the product; gradient heating can also reduce the internal stress concentration and defect generation caused by temperature fluctuations, thereby improving the overall performance of the product. Secondly, the appropriate temperature range can promote the movement and rearrangement of the polyamic acid molecular chain, which is conducive to the formation of a more regular and dense polyimide structure, which usually has higher mechanical properties and thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic diagram of a process for preparing a polybenzimidazole / polyetherimide composite thin film dielectric in the present invention;

[0031] Figure 2 Schematic diagram of the molecular structure of the polybenzimidazole / polyetherimide composite thin film dielectric prepared in Example 17 of the present invention;

[0032] Figure 3The Fourier transform infrared absorption spectra of the polybenzimidazole / polyetherimide and pure polyetherimide composite thin film dielectrics prepared in Examples 15, 16 and 17 of the present invention;

[0033] Figure 4 1 is a Weibull distribution statistical comparison diagram of the insulation properties of the polybenzimidazole / polyetherimide prepared in Examples 15, 16 and 17 of the present invention and pure polyetherimide;

[0034] Figure 5 This is a comparison chart of the energy storage density and energy storage efficiency of the polybenzimidazole / polyetherimide and pure polyetherimide composite thin film dielectrics prepared in Examples 15, 16 and 17 of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0037] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0038] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0039] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0040] like Figure 1 As shown, the present invention provides a method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric, comprising the following steps:

[0041] S1: N-methyl-2-pyrrolidone, 4,4-diaminodiphenyl ether, 1,2,4,5-benzenetetramine tetrahydrochloride and trimesic acid aldehyde are mixed and ultrasonically dispersed to obtain a uniform mixed solution;

[0042] Specifically, a certain amount of N-methyl-2-pyrrolidone, 4,4-diaminodiphenyl ether, trimesaldehyde and 1,2,4,5-benzenetetramine tetrahydrochloride can be weighed and mixed in a three-necked flask, and ultrasonically dispersed to obtain a uniform mixed solution, wherein the ultrasonic dispersion frequency is 1000-5000 Hz and the ultrasonic dispersion time is 1-3 minutes.

[0043] Among them, the structural formula of 4,4-diaminodiphenyl ether is:

[0044]

[0045] The structural formula of trimesaldehyde is:

[0046]

[0047] The structural formula of 1,2,4,5-benzenetetramine tetrahydrochloride is:

[0048]

[0049] S2: adding bisphenol A dianhydride to the mixed solution in batches, and stirring the mixture in an ice water bath at 0 to 10° C. under the protection of an inert atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid;

[0050] The mass ratio of 4,4-diaminodiphenyl ether to N-methyl-2-pyrrolidone is 1:(12-21); the mass ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is 1:(2.4-2.8); the mass ratio of 4,4-diaminodiphenyl ether to bisphenol A dianhydride is 1:(2.5-2.8). The ratio of the total mass of trimesaldehyde and 1,2,4,5-benzenetetramine tetrahydrochloride to the total mass of 4,4-diaminodiphenyl ether and bisphenol A dianhydride is (0.1-0.5):100. The inert atmosphere here is argon atmosphere, but is not limited to other inert atmospheres.

[0051] Among them, the molecular structure formula of bisphenol A dianhydride is:

[0052]

[0053] S3: The polybenzimidazole / polyetheramic acid composite colloid is subjected to vacuum treatment at room temperature to remove bubbles and a small amount of incompletely reacted solvent in the composite colloid, and then the polybenzimidazole / polyetheramic acid composite colloid is used to prepare a polybenzimidazole / polyetheramic acid composite film; the thickness of the polybenzimidazole / polyetheramic acid composite film is 8 to 15 μm. Here, a precision mechanical scraping technology can be used to prepare the polybenzimidazole / polyetheramic acid composite film. A composite film with controllable and uniform thickness can be obtained by a simple method, thereby reducing macroscopic defects and greatly improving the performance of the composite material; in addition, the vacuum treatment time is 300 to 720 minutes, the mechanical scraping rate is 5 to 15 cm / min, and the substrate can be a smooth glass substrate.

[0054] S4: drying the polybenzimidazole / polyetheramic acid composite film at 80°C for 300-600 minutes to remove the unreacted solvent N-methyl-2-pyrrolidone, and then performing imidization treatment. During the imidization treatment, the temperature is raised to the glass transition temperature of polyetherimide, and finally naturally cooled to room temperature to obtain the polybenzimidazole / polyetherimide composite film dielectric, whose structural formula is as follows: Figure 2 The imidization treatment process is specifically as follows: the heating rate is 1.5-2°C / min, and the temperature is gradually increased within the range of 100-300°C.

[0055] In the preparation method, first, N-methyl-2-pyrrolidone (NMP), 4,4-diaminodiphenyl ether (ODA), 1,2,4,5-benzene tetraamine tetrahydrochloride and trimesic acid are mixed, and then ultrasonically dispersed to obtain a uniform mixed solution, wherein NMP is used as a solvent to dissolve reactants and promote uniform mixing of reactants during the reaction process, and it helps each reaction monomer to fully contact at the molecular level, thereby improving the reaction efficiency and the uniformity of the product; secondly, bisphenol A dianhydride is added to the mixed solution, and stirred in an ice water bath under the protection of an inert atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid, in which trimesic acid can react with 1,2,4,5-benzene tetraamine tetrahydrochloride to generate polybenzimidazole (PBI), and promote the growth and polymerization of polybenzimidazole chain segments to form a stable poly The cross-linked structure of the benzimidazole chain segments enhances the thermal stability, chemical stability, cohesion and mechanical properties of the composite material; in addition, in the reaction system, bisphenol A dianhydride can react with 4,4-diaminodiphenyl ether to generate polyetheramic acid, thereby realizing the synchronous polymerization and mutual cross-linking of polyetheramic acid and polybenzimidazole; in the reaction process, the inert atmosphere can effectively isolate impurities such as oxygen and moisture in the air, making it easier to react to generate polybenzimidazole-linked polymers, which are not easily oxidized; stirring the reaction in an ice-water bath can reduce the occurrence of reverse reaction of the polymerization reaction, thereby improving its polymerization efficiency and the yield of the composite material; finally, the polybenzimidazole / polyetheramic acid colloid after film formation is subjected to imidization treatment to obtain the polybenzimidazole / polyetherimide composite thin film dielectric.

[0056] In addition, the present invention also discloses a polybenzimidazole / polyetherimide composite film dielectric, which is prepared by the above method. In the composite film dielectric, the mass ratio of polybenzimidazole to polyetherimide is (0.1-0.5):100. The present invention introduces a small amount of polybenzimidazole to connect the polymer to prepare the composite film of polybenzimidazole / polyetherimide. The polybenzimidazole to connect the polymer has excellent thermal stability, chemical stability, high specific surface area and dielectric properties, etc. The introduction of the polybenzimidazole to connect the polymer improves the energy storage performance of the film while enhancing its stability at high temperature, and the chain structure of the polybenzimidazole / polyetherimide molecules is closely arranged and combined, effectively reducing the free volume, reducing structural defects, greatly improving the breakdown field strength of the polymer, improving the polarization strength of the composite material, and avoiding the electric field distortion caused by the mismatch of the dielectric constant and conductivity between the filler and the matrix. At the same time, the composite film has high tensile strength and modulus, giving the polybenzimidazole / polyetherimide dielectric film excellent mechanical processing properties. At the same time, if Figure 2As shown, the amino cross-linked region formed between polybenzimidazole and polyetherimide significantly improves the molecular interaction force between the chains of the composite material, strengthens the breakdown field strength of the composite material, and suppresses the dielectric loss. That is, the present invention uses mild conditions, simple operation, synchronous polymerization process and gradient temperature imidization preparation process to add polybenzimidazole to polyetheramic acid to form a composite film, and obtain a polybenzimidazole / polyetherimide composite film, which solves the problem of low polarization strength of polyetherimide. The obtained polybenzimidazole / polyetherimide composite film is dense and defect-free, and the cross-linking effect of polybenzimidazole and polyetherimide realizes an organic composite film material with good internal and external matching. Compared with the existing technology, this scheme can improve the polarization strength of the composite material by adding a small amount of polybenzimidazole, effectively avoids the electric field distortion caused by the mismatch of the dielectric constant and conductivity between the doped filler and the matrix, improves the breakdown field strength of the polybenzimidazole / polyetherimide composite material, and realizes the improvement of the energy storage density of the composite film material. At the same time, the polybenzimidazole / polyetherimide composite film material exhibits excellent energy storage properties under high temperature conditions.

[0057] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0058] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0059] Example 1

[0060] A method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric comprises the following steps:

[0061] Step 1: Preparation of polybenzimidazole / polyetheramic acid composite colloid: 31.434 g of N-methyl-2-pyrrolidone, 1.500 g of 4,4-diaminodiphenyl ether, 0.00774 g of trimesaldehyde and 0.02035 g of 1,2,4,5-benzenetetramine tetrahydrochloride were mixed in a three-necked flask, and dispersed for 3 minutes at an ultrasonic frequency of 5000 Hz to obtain a uniform mixed organic solution, and argon gas was introduced. The mixture was placed in an ice water bath and stirred. 4.019 g of bisphenol A dianhydride was added to the mixed solution in batches at the amounts of 1.000 g, 1.000 g, 1.000 g, 0.500 g, 0.200 g, 0.200 g and 0.119 g, respectively, for reaction. The time intervals for adding 1.000 g and 0.500 g were 30 min, and the time intervals for adding 0.200 g and 0.119 g were 10 min. After the addition, stirring was continued for 30 min to obtain a polybenzimidazole / polyether amic acid composite colloid.

[0062] Step 2: Preparation of polybenzimidazole / polyetheramic acid composite film: The polybenzimidazole / polyetheramic acid composite colloid is subjected to a vacuum treatment at room temperature at 0.1 MPa to remove bubbles in the composite colloid and a small amount of incompletely reacted solvent for 300 min. The treated composite colloid is applied on a smooth glass substrate and scraped into a 15 μm film using precision mechanical scraping technology at a scraping rate of 15 cm / min to obtain a polybenzimidazole / polyetheramic acid composite film.

[0063] Step 3: Preparation of polybenzimidazole / polyetherimide composite film: Place the polybenzimidazole / polyetheramic acid composite film in a precision high-temperature drying oven and dry it at 80°C for 300 minutes, and perform gradient temperature imidization at 150°C, 200°C, 250°C and 300°C in sequence. The treatment time at each temperature is 1 hour, and then cool to room temperature to obtain a polybenzimidazole / polyetherimide composite film.

[0064] The polybenzimidazole / polyetherimide composite film prepared by the present invention was gold plated in a vacuum gold plating instrument with a diameter of 0.3 cm, and then the dielectric properties and energy storage density were tested. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 0.174 J / cm at a field strength of 100 kV / mm. 3 .

[0065] Example 2

[0066] A method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric comprises the following steps:

[0067] Step 1: Preparation of polybenzimidazole / polyetheramic acid composite colloid: 31.434 g of N-methyl-2-pyrrolidone, 1.500 g of 4,4-diaminodiphenyl ether, 0.00774 g of trimesaldehyde and 0.02035 g of 1,2,4,5-benzenetetramine tetrahydrochloride were mixed in a three-necked flask, and dispersed for 3 minutes under ultrasonic frequency of 1000 Hz to obtain a uniform mixed organic solution, and argon gas was introduced. The mixture was placed in an ice water bath and stirred, and 4.019 g of bisphenol A dianhydride was added in batches in the amounts of 1.000 g, 1.000 g, 1.000 g, 0.500 g, 0.200 g, 0.200 g and 0.119 g to react with the mixed solution, wherein the time interval for adding 1.000 g and 0.500 g was 30 min, and the time interval for adding 0.200 g and 0.119 g was 10 min. After adding, stirring was continued for 30 min to obtain a polybenzimidazole / polyether amic acid composite colloid.

[0068] Step 2: Preparation of polybenzimidazole / polyetheramic acid composite film: The polybenzimidazole / polyetheramic acid composite colloid is subjected to a vacuum treatment at room temperature at 0.1 MPa to remove bubbles in the composite colloid and a small amount of incompletely reacted solvent for 300 min. The treated composite colloid is applied on a smooth glass substrate and scraped into a 15 μm film using precision mechanical scraping technology at a scraping rate of 15 cm / min to obtain a polybenzimidazole / polyetheramic acid composite film.

[0069] Step 3: Preparation of polybenzimidazole / polyetherimide composite film: Place the polybenzimidazole / polyetheramic acid composite film in a precision high-temperature drying oven and dry it at 80°C for 300 minutes, and then perform gradient temperature imidization at 150°C, 200°C, 250°C and 300°C in sequence. The treatment time at each temperature is 1 hour, and then cool to room temperature to obtain the polybenzimidazole / polyetherimide composite film.

[0070] The polybenzimidazole / polyetherimide composite film prepared by the present invention was gold plated in a vacuum gold plating instrument with a diameter of 0.3 cm, and then the dielectric properties and energy storage density were tested. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 0.429 J / cm at a field strength of 120 kV / mm. 3 .

[0071] Embodiment 3:

[0072] A polybenzimidazole / polyetherimide composite thin film dielectric and a preparation method thereof, comprising the following steps:

[0073] Step 1: Preparation of polybenzimidazole / polyetheramic acid composite colloid: 31.434 g of N-methyl-2-pyrrolidone, 1.500 g of 4,4-diaminodiphenyl ether, 0.00774 g of trimesaldehyde and 0.02035 g of 1,2,4,5-benzenetetramine tetrahydrochloride were mixed in a three-necked flask, and the mixture was dispersed at an ultrasonic frequency of 3000 Hz for 1 min to obtain a uniform mixed organic solution, and argon gas was introduced. The mixture was placed in an ice water bath and stirred, and 4.019 g of bisphenol A dianhydride was added in batches in the amounts of 1.000 g, 1.000 g, 1.000 g, 0.500 g, 0.200 g, 0.200 g and 0.119 g to react with the mixed solution, wherein the time interval for adding 1.000 g and 0.500 g was 30 min, and the time interval for adding 0.200 g and 0.119 g was 10 min. After the addition, stirring was continued for 60 min to obtain a polybenzimidazole / polyether amic acid composite colloid.

[0074] Step 2: Preparation of polybenzimidazole / polyetheramic acid composite film: The polybenzimidazole / polyetheramic acid composite colloid is subjected to a vacuum treatment at room temperature at 0.1 MPa to remove bubbles in the composite colloid and a small amount of incompletely reacted solvent for 300 min. The treated composite colloid is applied on a smooth glass substrate and scraped into a 15 μm film using precision mechanical scraping technology at a scraping rate of 15 cm / min to obtain a polybenzimidazole / polyetheramic acid composite film.

[0075] Step 3: Preparation of polybenzimidazole / polyetherimide composite film: Place the polybenzimidazole / polyetheramic acid composite film in a precision high-temperature drying oven and dry it at 80°C for 300 minutes, and then perform gradient temperature imidization at 150°C, 200°C, 250°C and 300°C in sequence. The treatment time at each temperature is 1 hour, and then cool to room temperature to obtain the polybenzimidazole / polyetherimide composite film.

[0076] The polybenzimidazole / polyetherimide composite film prepared by the present invention was gold plated in a vacuum gold plating instrument with a diameter of 0.3 cm, and then the dielectric properties and energy storage density were tested. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 1.503 J / cm at a field strength of 260 kV / mm. 3 .

[0077] Example 4

[0078] The difference between this embodiment and embodiment 3 is that in step 2, the bubbles in the composite colloid and a small amount of unreacted solvent are vacuum-extracted for 460 minutes. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 1.370 J / cm at a field strength of 280 kV / mm. 3 .

[0079] Example 5

[0080] The difference between this embodiment and embodiment 3 is that in step 2, the bubbles in the composite colloid and a small amount of unreacted solvent are vacuum-extracted for 720 minutes. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 1.441 J / cm at a field strength of 300 kV / mm. 3 .

[0081] Example 6

[0082] The difference between this embodiment and embodiment 5 is that in step 2, a precision mechanical scraping technique is used to scrape an 8 μm film at a scraping rate of 5 cm / min. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 1.023 J / cm at a field strength of 260 kV / mm. 3 .

[0083] Example 7

[0084] The difference between this embodiment and embodiment 5 is that in step 2, a precision mechanical scraping technique is used to scrape a 13 μm film at a scraping rate of 10 cm / min. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 2.065 J / cm at a field strength of 350 kV / mm. 3 .

[0085] Example 8

[0086] The difference between this embodiment and embodiment 7 is that in step 3, the polybenzimidazole / polyetheramic acid composite film is placed in a precision high-temperature drying oven at 80°C for 450 minutes. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 2.071 J / cm at a field strength of 380 kV / mm. 3 .

[0087] Example 9

[0088] The difference between this embodiment and embodiment 7 is that in step 3, the polybenzimidazole / polyetheramic acid composite film is placed in a precision high-temperature drying oven at 80°C for 600 minutes. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 2.528 J / cm at a field strength of 400 kV / mm. 3 .

[0089] Example 10

[0090] The difference between this embodiment and embodiment 9 is that 0.003096 g of trimesaldehyde and 0.008138 g of 1,2,4,5-benzenetetramine tetrahydrochloride are used in step 1. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 3.062 J / cm at a field strength of 440 kV / mm. 3 .

[0091] Embodiment 11

[0092] The difference between this embodiment and embodiment 9 is that 0.001548 g of trimesaldehyde and 0.004069 g of 1,2,4,5-benzenetetramine tetrahydrochloride are used in step 1. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 4.140 J / cm at a field strength of 520 kV / mm. 3 .

[0093] Example 12

[0094] The difference between this embodiment and embodiment 9 is that the mass ratio of 4,4-diaminodiphenyl ether to N-methyl-2-pyrrolidone in step 1 is 1:12. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 2.528 J / cm at a field strength of 400 kV / mm. 3 .

[0095] Embodiment 13

[0096] The difference between this embodiment and embodiment 9 is that the mass ratio of 4,4-diaminodiphenyl ether to N-methyl-2-pyrrolidone in step 1 is 1:16. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 1.888 J / cm at a field strength of 500 kV / mm. 3 .

[0097] Embodiment 14

[0098] The difference between this embodiment and embodiment 9 is that the mass ratio of 4,4-diaminodiphenyl ether to N-methyl-2-pyrrolidone in step 1 is 1:14. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 5.668 J / cm at a field strength of 540 kV / mm. 3 .

[0099] Embodiment 15

[0100] The difference between this embodiment and embodiment 13 is that in step 1, 0.00774 g of trimesaldehyde and 0.02035 g of 1,2,4,5-benzenetetramine tetrahydrochloride are used. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 5.351 J / cm at a field strength of 600 kV / mm. 3 .

[0101] Example 16

[0102] The difference between this embodiment and embodiment 15 is that in step 1, 0.003096 g of trimesaldehyde and 0.008138 g of 1,2,4,5-benzenetetramine tetrahydrochloride are used. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 3.236 J / cm at a field strength of 500 kV / mm. 3 .

[0103] Embodiment 17

[0104] The difference between this embodiment and embodiment 15 is that in step 1, 0.001548 g of trimesaldehyde and 0.004069 g of 1,2,4,5-benzenetetramine tetrahydrochloride are used. The polybenzimidazole / polyetherimide film capacitor prepared in this embodiment has a maximum discharge energy density of 7.258 J / cm at a field strength of 620 kV / mm. 3 .

[0105] Figure 3 The Fourier transform infrared absorption spectra of the polybenzimidazole / polyetherimide and pure polyetherimide composite film dielectrics prepared in Examples 15, 16 and 17 of the present invention are shown in the figure. -1 The prepared composite material showed an absorption peak in the cumulative double bond area compared to polyetherimide. The formation of the special structure of polybenzimidazole / polyetherimide will cause the stacking of C=N double bonds and C=O double bonds, thus forming this type of peak, indicating the successful preparation of polybenzimidazole / polyetherimide composite thin film dielectrics.

[0106] Figure 4 This is a statistical comparison diagram of the Weibull distribution of the insulating properties of the polybenzimidazole / polyetherimide composite film dielectrics and pure polyetherimide prepared in Examples 15, 16 and 17 of the present invention. Compared with polyetherimide, the insulating properties of the polybenzimidazole / polyetherimide composite film dielectrics of each component are significantly improved.

[0107] Figure 5The energy storage density and energy storage efficiency of the polybenzimidazole / polyetherimide composite thin film dielectric prepared in Examples 15, 16 and 17 of the present invention are compared. At 25°C, 0.1wt% polybenzimidazole / polyetherimide composite thin film dielectric obtained 4.7Jcm when the energy storage efficiency was greater than 90%. -3 The discharge energy density is higher than that of polyetherimide at the same temperature, which is 3.2 J cm -3 , and at 620kV mm -1 The breakdown field strength is 7.258 J cm, while maintaining an efficiency of 87%. -3 The discharge energy density is 126.5% higher than the energy density of the original PEI at the breakdown field strength.

[0108] Embodiment 18

[0109] A method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric comprises the following steps:

[0110] S1: N-methyl-2-pyrrolidone, 4,4-diaminodiphenyl ether, 1,2,4,5-benzenetetraamine tetrahydrochloride and trimesic acid aldehyde were mixed, and ultrasonically dispersed at a frequency of 1000 Hz for 3 minutes to obtain a uniform mixed solution;

[0111] S2: adding bisphenol A dianhydride to the mixed solution in batches, and stirring the mixture in an ice water bath at 0°C under the protection of an argon atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid; wherein the mass ratio of 4,4-diaminodiphenyl ether to N-methyl-2-pyrrolidone is 1:12; the mass ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is 1:2.4; the mass ratio of 4,4-diaminodiphenyl ether to bisphenol A dianhydride is 1:2.5; the ratio of the total mass of trimesaldehyde and 1,2,4,5-benzenetetramine tetrahydrochloride to the total mass of 4,4-diaminodiphenyl ether and bisphenol A dianhydride is 0.1:100.

[0112] S3: The polybenzimidazole / polyether amic acid composite colloid is subjected to vacuum treatment at room temperature for 300 minutes to remove bubbles and a small amount of incompletely reacted solvent in the composite colloid, and then the polybenzimidazole / polyether amic acid composite colloid is used to prepare a polybenzimidazole / polyether amic acid composite film; the thickness of the polybenzimidazole / polyether amic acid composite film is 8 μm.

[0113] S4: drying the polybenzimidazole / polyetheramic acid composite film at 80°C for 300 minutes to remove the unreacted solvent N-methyl-2-pyrrolidone, and then performing imidization treatment. During the imidization treatment, the temperature is raised to the glass transition temperature of polyetherimide, and finally naturally cooled to room temperature to obtain the polybenzimidazole / polyetherimide composite film dielectric. The imidization treatment process is specifically as follows: the heating rate is 1.5°C / min, and the gradient temperature treatment is performed within the range of 100°C.

[0114] Embodiment 19

[0115] A method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric comprises the following steps:

[0116] S1: N-methyl-2-pyrrolidone, 4,4-diaminodiphenyl ether, 1,2,4,5-benzenetetraamine tetrahydrochloride and trimesic acid aldehyde were mixed, and ultrasonically dispersed at a frequency of 5000 Hz for 1 min to obtain a uniform mixed solution;

[0117] S2: adding bisphenol A dianhydride to the mixed solution in batches, and reacting with stirring in an ice water bath at 10°C under the protection of an argon atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid; wherein the mass ratio of 4,4-diaminodiphenyl ether to N-methyl-2-pyrrolidone is 1:21; the mass ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is 1:2.8; the mass ratio of 4,4-diaminodiphenyl ether to bisphenol A dianhydride is 1:2.8; the ratio of the total mass of trimesaldehyde and 1,2,4,5-benzenetetramine tetrahydrochloride to the total mass of 4,4-diaminodiphenyl ether and bisphenol A dianhydride is 0.5:100.

[0118] S3: The polybenzimidazole / polyether amic acid composite colloid is subjected to vacuum treatment at room temperature for 720 minutes to remove bubbles and a small amount of incompletely reacted solvent in the composite colloid, and then the polybenzimidazole / polyether amic acid composite colloid is used to prepare a polybenzimidazole / polyether amic acid composite film; the thickness of the polybenzimidazole / polyether amic acid composite film is 15 μm.

[0119] S4: drying the polybenzimidazole / polyetheramic acid composite film at 80°C for 600 minutes to remove the unreacted solvent N-methyl-2-pyrrolidone, and then performing imidization treatment. During the imidization treatment, the temperature is raised to the glass transition temperature of polyetherimide, and finally naturally cooled to room temperature to obtain the polybenzimidazole / polyetherimide composite film dielectric. The imidization treatment process is specifically as follows: the heating rate is 2°C / min, and the gradient temperature treatment is performed within the range of 300°C.

[0120] Embodiment 20

[0121] A method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric comprises the following steps:

[0122] S1: N-methyl-2-pyrrolidone, 4,4-diaminodiphenyl ether, 1,2,4,5-benzenetetraamine tetrahydrochloride and trimesic acid were mixed, and then ultrasonically dispersed at a frequency of 3000 Hz for 2 minutes to obtain a uniform mixed solution;

[0123] S2: adding bisphenol A dianhydride to the mixed solution in batches, and stirring the mixture in an ice water bath at 0-10°C under argon atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid; wherein the mass ratio of 4,4-diaminodiphenyl ether to N-methyl-2-pyrrolidone is 1:18; the mass ratio of trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is 1:2.5; the mass ratio of 4,4-diaminodiphenyl ether to bisphenol A dianhydride is 1:2.6; the ratio of the total mass of trimesaldehyde and 1,2,4,5-benzenetetramine tetrahydrochloride to the total mass of 4,4-diaminodiphenyl ether and bisphenol A dianhydride is 0.3:100.

[0124] S3: The polybenzimidazole / polyether amic acid composite colloid is subjected to vacuum treatment at room temperature for 500 minutes to remove bubbles and a small amount of incompletely reacted solvent in the composite colloid, and then the polybenzimidazole / polyether amic acid composite colloid is used to prepare a polybenzimidazole / polyether amic acid composite film; the thickness of the polybenzimidazole / polyether amic acid composite film is 10 μm.

[0125] S4: drying the polybenzimidazole / polyetheramic acid composite film at 80°C for 400 minutes to remove the unreacted solvent N-methyl-2-pyrrolidone, and then performing imidization treatment. During the imidization treatment, the temperature is raised to the glass transition temperature of polyetherimide, and finally naturally cooled to room temperature to obtain the polybenzimidazole / polyetherimide composite film dielectric. The imidization treatment process is specifically as follows: the heating rate is 1.8°C / min, and the gradient temperature treatment is performed within the range of 200°C.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric, characterized in that: The following steps are involved: S1: N-methyl-2-pyrrolidone, 4,4-diaminodiphenyl ether, 1,2,4,5-benzenetetramine tetrahydrochloride and trimesic acid aldehyde are mixed and ultrasonically dispersed to obtain a uniform mixed solution; S2: adding bisphenol A dianhydride to the mixed solution, and stirring the mixture in an ice-water bath under the protection of an inert atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid; S3: using the polybenzimidazole / polyetheramic acid composite colloid to prepare a polybenzimidazole / polyetheramic acid composite film; S4: performing imidization treatment on the polybenzimidazole / polyetheramic acid composite film to obtain the polybenzimidazole / polyetherimide composite film dielectric.

2. The method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric according to claim 1, characterized in that: The mass ratio of the trimesaldehyde to 1,2,4,5-benzenetetramine tetrahydrochloride is 1:(2.4-2.8); the mass ratio of the 4,4-diaminodiphenyl ether to bisphenol A dianhydride is 1:(2.5-2.8).

3. The method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric according to claim 1, characterized in that: The ratio of the total mass of trimesaldehyde and 1,2,4,5-benzenetetraamine tetrahydrochloride to the total mass of 4,4-diaminodiphenyl ether and bisphenol A dianhydride is (0.1-0.5):

100.

4. The method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric according to claim 1, characterized in that: In step S2, the bisphenol A dianhydride is added to the mixed solution in batches.

5. The method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric according to claim 1, characterized in that: In step S3, before using the polybenzimidazole / polyetheramic acid composite colloid to prepare the polybenzimidazole / polyetheramic acid composite film, the polybenzimidazole / polyetheramic acid composite colloid is subjected to vacuum treatment at room temperature.

6. The method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric according to claim 1, characterized in that: In step S3, the thickness of the polybenzimidazole / polyether amic acid composite film is 8-15 μm.

7. The method for preparing a polybenzimidazole / polyetherimide composite thin film dielectric according to claim 1, characterized in that: In step S4, the imidization treatment process is specifically as follows: the heating rate is 1.5-2°C / min, and the gradient heating treatment is performed in the range of 100-300°C.

8. A polybenzimidazole / polyetherimide composite thin film dielectric, characterized in that: It is prepared by the method according to any one of claims 1 to 8.

9. The polybenzimidazole / polyetherimide composite thin film dielectric according to claim 8, characterized in that: In the composite thin film dielectric, the mass ratio of polybenzimidazole to polyetherimide is (0.1-0.5):

100.

10. Use of a polybenzimidazole / polyetherimide composite film dielectric as claimed in any one of claims 8 to 9 in a polymer-based film capacitor.

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