A polybenzimidazole / polyetherimide composite film dielectric and its preparation method and application

Abstract

The application discloses a polybenzimidazole / polyetherimide composite thin film dielectric and a preparation method and application thereof, the method uses N-methyl-2-pyrrolidone, 4,4-diamino diphenyl ether, 1,2,4,5-benzene tetraamine tetrahydrochloride, trimesic aldehyde and bisphenol A dianhydride as raw materials, polybenzimidazole is generated at the same time of generating polyetherimide, and the two are synchronously crosslinked, and the prepared polybenzimidazole / polyetherimide composite thin film dielectric is obtained. The improved polyetherimide preparation process is mild in condition, simple in operation and easy to scale production, the obtained composite thin film dielectric is applied to an energy storage battery, and has higher energy storage energy density, higher breakdown strength and other dielectric properties.

Description

TECHNICAL FIELD

[0001] The application 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

[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. Thin film capacitors have high power density, fast energy release rate, high normal operating temperature and other advantages, and are widely used in motor drives, mobile power systems, space vehicle power supplies and other high-power pulse 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 to expand their operating temperature range (25-250℃).

[0003] Dielectric materials are divided into two categories: organic polymers and inorganic ceramics. Polymer dielectrics store and release energy through local dipole ring polarization, achieve fast charge and discharge, and have high breakdown field strength (E b ), low dielectric loss, good flexibility, etc. However, existing polymer dielectric materials, such as biaxially oriented polypropylene film (BOPP), polycarbonate (PC), polyimide (PI), fluorene polyester (FPE) and poly-ether-ether-ketone (PEEK), etc., have low dielectric constant, significant degradation of breakdown field strength under high temperature conditions (>100℃), etc. The glass transition temperature (T g ) of polyetherimide (PEI) is about 217℃, and it has high dielectric constant (ε r =3.2), low dielectric loss (0.29%), flexibility, processability, etc. Under high temperature conditions, PEI can still maintain 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. Inorganic nano-filler (Al2O3, HfO2, BaTiO3, BNNS, etc.) is doped in polymer dielectrics to improve their performance under high temperature conditions. However, a large amount of inorganic nano-filler needs to be doped to significantly improve the dielectric constant of the polymer dielectric. This method has a complex preparation process, reduces the flexibility, uniformity and processability of the polymer-based composite material, causes a decrease in mechanical properties, and increases the cost of large-scale film production. At the same time, a large amount of inorganic nanoparticles and organic polymer interface produce dielectric mismatch effect, which reduces the breakdown field strength. SUMMARY

[0004] In order to solve the problems in the prior art, the application provides a polybenzimidazole / polyetherimide composite film dielectric, a preparation method and application thereof, so as to solve the technical problems that when the inorganic nano filler 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 between the inorganic nanoparticles and the organic polymer reduces the breakdown field strength.

[0005] The application is realized by the following technical scheme:

[0006] The application provides a preparation method of a polybenzimidazole / polyetherimide composite film dielectric, which comprises the following steps:

[0007] S1: mixing N-methyl-2-pyrrolidone, 4,4-diamino diphenyl ether, 1,2,4,5-benzene tetramine tetrahydrochloride and trimesaldehyde, and then performing ultrasonic dispersion to obtain a uniform mixed solution;

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

[0009] S3: preparing a polybenzimidazole / polyether amide acid composite film by using the polybenzimidazole / polyether amide acid composite colloid;

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

[0011] Preferably, the mass ratio of the trimesaldehyde to the 1,2,4,5-benzene tetramine tetrahydrochloride is 1:(2.4-2.8), and the mass ratio of the 4,4-diamino diphenyl ether to the bisphenol A dianhydride is 1:(2.5-2.8).

[0012] Preferably, the total mass of the trimesaldehyde and the 1,2,4,5-benzene tetramine tetrahydrochloride and the total mass of the 4,4-diamino diphenyl ether and the bisphenol A dianhydride are in a ratio of (0.1-0.5):100.

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

[0014] Preferably, in the step S3, before the polybenzimidazole / polyether amide acid composite film is prepared by using the polybenzimidazole / polyether amide acid composite colloid, the polybenzimidazole / polyether amide acid composite colloid is subjected to vacuum treatment under normal temperature conditions.

[0015] Preferably, in step S3, the thickness of the polybenzimidazole / polyether amide acid composite film is 8-15 microns.

[0016] Preferably, in step S4, the imidization process is performed at a temperature increasing rate of 1.5-2 DEG C / min and a gradient temperature increasing process is performed at 100-300 DEG C.

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

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

[0019] The above polybenzimidazole / polyetherimide composite film dielectric is applied to a polymer-based thin film capacitor.

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

[0021] The present application discloses a preparation method of a polybenzimidazole / polyetherimide composite film dielectric, in which, firstly, the introduction of polybenzimidazole connecting polymers improves the energy storage performance of the film and enhances its stability at high temperatures; secondly, both polybenzimidazole (PBI) and polyetherimide (PEI) molecules are chain structures, and both contain cyclic pi bonds, which are arranged and combined through pi-pi conjugation; in addition, polybenzimidazole molecules contain C=O and polyetherimide molecules contain C=N, which can form cumulative double bonds through conjugation, i.e., an amino crosslinking region, two kinds of conjugation effectively reduce free volume, reduce structural defects, significantly improve the inter-chain molecular force of the composite material, greatly improve the breakdown field strength of the polymer, 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 electrical conductivity between the filler and the matrix; finally, due to the existence of two kinds of conjugation, the tensile strength and modulus of the composite material are improved, which endows the polybenzimidazole / polyetherimide dielectric film with excellent mechanical processing performance.

[0022] Further, the mass ratio of the trimesic acid and the 1,2,4,5-benzene tetraamine tetrahydrochloride is 1:(2.4-2.8). First, a proper mass ratio can ensure that the reactants are fully contacted in the solution, thereby accelerating the rate of polymerization. Too high or too low a ratio of trimesic acid to benzene tetraamine tetrahydrochloride can affect the reaction rate, leading to 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 subsequent compounding with polyether amide acid and the performance of the final film. Second, the ratio of trimesic acid to benzene tetraamine tetrahydrochloride directly affects the length and cross-linking degree of the PBI segment, and in turn affects the mechanical properties of the composite film. A proper mass ratio can optimize the mechanical indicators such as tensile strength and modulus of the film. The stability of the PBI segment has an important influence on the thermal stability of the composite film, and a reasonable mass ratio can ensure that the PBI segment still maintains a stable structure at high temperatures, thereby improving the thermal stability of the film. Finally, a proper mass ratio can make the composite colloid flow and spread more easily during processing, thereby improving the film-forming property and surface flatness of the film. In addition, a proper mass ratio can reduce unnecessary side reactions, making the polymerization reaction more controllable, and thus obtaining a purer polymer product. In summary, the mass ratio of trimesic acid to 1,2,4,5-benzene tetraamine tetrahydrochloride is set to 1:(2.4-2.8) based on the comprehensive consideration of polymerization efficiency, product quality, film performance, processing performance, and reaction controllability, etc. This setting helps to prepare a polybenzimidazole / polyetherimide composite film dielectric with excellent performance.

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

[0024] Further, the total mass ratio of the trimesalicylaldehyde to the 1,2,4,5-benzene tetraamine tetrahydrochloride to the total mass of the 4,4-diamino diphenyl ether and the bisphenol A dianhydride is (0.1-0.5):100, firstly, this ratio setting allows fine adjustment of the relative content of the polybenzimidazole (PBI) and the polyetherimide (PEI) in the composite film, the introduction of PBI can improve the energy storage performance of the film at high temperatures, 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, the two polymers can be ensured to work together in the composite film to achieve the best balance in performance, at the same time, the two polymers have strong conjugated bonds, therefore, the performance requirements can be met by introducing a small amount of benzimidazole, and the influence 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 between bisphenol A dianhydride and 4, 4-diamino diphenyl ether is an exothermic process, and adding BPADA in batches can gradually release the heat of reaction, avoid local temperature too high caused by adding once, thereby controlling the reaction rate within a suitable range, reducing the occurrence of side reactions, and improving the purity and quality of the product. Gradual addition of BPADA can ensure that the reactants are more uniformly distributed in the mixed solution, making the reaction more uniform, which is conducive to the formation of polymers with uniform structure and stable performance. Second, during the process of adding BPADA in batches, the mixed solution can be continuously stirred to make the newly added BPADA disperse rapidly and fully contact with the reactants, promote the uniform mixing of the solution, and good solution mixing state is conducive to the full contact and collision between reactants, thereby improving the reaction efficiency and reducing the reaction time.

[0026] Further, in step S3, before preparing the polybenzimidazole / polyether amide acid composite film using the polybenzimidazole / polyether amide acid composite colloid, the polybenzimidazole / polyether amide acid composite colloid is subjected to vacuum treatment at room temperature. The vacuum treatment can effectively remove bubbles in the film, obtaining a dense and defect-free polybenzimidazole / polyether amide composite film. First, the presence of bubbles is an important defect of the film quality, which can cause the mechanical properties of the film to decrease, such as tensile strength, bending strength, etc. By removing bubbles through vacuum treatment, the number of defects in the film can be significantly reduced, thereby improving the overall quality of the film. Second, bubbles can also affect the flatness of the film, making the film surface uneven. By removing bubbles through vacuum treatment, the film surface can be made more flat, which is conducive to subsequent processing and use; the presence of bubbles can also cause the film to break or be damaged during subsequent processing, thereby reducing the yield. By removing bubbles through vacuum treatment, the processing stability and yield of the film can be improved; bubbles can also cause the film to be eroded by the external environment during use, thereby accelerating aging. After removing bubbles, the durability of the film can be improved, thereby prolonging its service life.

[0027] Further, in step S3, the thickness of the polybenzimidazole / polyether amide acid composite film is 8-15 μm. Firstly, within this thickness range, the film generally exhibits good mechanical properties, such as high tensile strength, modulus and toughness; the appropriate thickness helps to optimize the dielectric constant, dielectric loss and breakdown field strength of the film. Secondly, the thinner thickness makes it easier to achieve uniform distribution of the film during coating, reducing the performance difference caused by uneven thickness; when preparing the composite film, the thinner thickness facilitates the close fit of the laminated material, improving the lamination effect and thus enhancing the overall performance of the film. In addition, with the rapid development of flexible electronics technology, the demand for film materials is increasing, and the thickness of 8-15 μm makes the polybenzimidazole / polyether amide acid composite film have broad application prospects in the field of flexible electronics such as flexible displays and wearable devices, and the appropriate thickness setting can maintain stable performance in high temperature environment.

[0028] Further, in step S4, the imidization process is as follows: the temperature rising rate is 1.5-2℃ / min, and the gradient temperature rising treatment is performed within the range of 100-300℃. Firstly, the gradient temperature rising gradually increases the temperature, avoiding sharp changes in 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 temperature rising, the temperature distribution of the film during the entire heating process is more uniform, which is conducive to the uniform reaction and uniformity of the product. Gradient temperature rising 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 polyamide acid molecular chains, which is conducive to the formation of more regular and dense polyimide structure, which usually has higher mechanical properties and thermal stability. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0030] Figure 1 The flowchart of the preparation method of the polybenzimidazole / polyether imide composite film dielectric in the present application is shown in the figure.

[0031] Figure 2 The molecular structure of the polybenzimidazole / polyether imide composite film dielectric prepared in Example 17 in the present application is shown in the figure.

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

[0033] Figure 4 The insulation performance Weibull distribution statistics comparison chart of the polybenzimidazole / polyetherimide composite thin film dielectric prepared in Examples 15, 16 and 17 of the present application and the pure polyetherimide;

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

[0035] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings understood by those skilled in the art of the present application, and in the event of conflict, the definitions in the specification shall prevail.

[0036] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting the scope of the present application, i.e., the present application can be practiced without relying on any particular theory or mechanism.

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

[0038] Herein, unless otherwise specified, "comprise", "include", "contain", "have" or similar words encompass the meaning of "consist of" and "consist essentially of", for example, "A comprises a" encompasses the meaning of "A comprises a and other" and "A comprises only a".

[0039] Herein, for the sake of brevity, all possible combinations of the technical features in each embodiment or example are not described. Therefore, as long as the combinations of the technical features do not conflict, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope disclosed in the specification.

[0040] As Figure 1 shown, the present application provides a preparation method of a polybenzimidazole / polyetherimide composite thin film dielectric, comprising the following steps:

[0041] S1: mixing N-methyl-2-pyrrolidone, 4,4-diamino diphenyl ether, 1,2,4,5-benzene tetramine tetrahydrochloride and trimesaldehyde, and then ultrasonic dispersion to obtain a uniform mixed solution;

[0042] Specifically, a certain amount of N-methyl-2-pyrrolidone, 4,4-diamino diphenyl ether, trimesaldehyde and 1,2,4,5-benzene tetramine tetrahydrochloride can be weighed respectively in a three-necked flask, ultrasonic dispersion to obtain a uniform mixed solution. The ultrasonic dispersion frequency is 1000-5000 Hz, and the ultrasonic dispersion time is 1-3 min.

[0043] The structural formula of 4,4-diamino diphenyl ether is:

[0044]

[0045] The structural formula of trimesaldehyde is:

[0046]

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

[0048]

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

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

[0051] The molecular structural formula of bisphenol A dianhydride is:

[0052]

[0053] S3: The polybenzimidazole / polyether amide acid composite gel is vacuum treated at room temperature to remove bubbles and a small amount of incompletely reacted solvent in the composite gel, and then the polybenzimidazole / polyether amide acid composite film is prepared using the polybenzimidazole / polyether amide acid composite gel; the thickness of the polybenzimidazole / polyether amide acid composite film is 8-15 μm. Here, the polybenzimidazole / polyether amide acid composite film can be prepared using a precision mechanical scraping coating technique, and a composite film with controllable and uniform thickness can be prepared by a simple method, macroscopic defects are reduced, and the performance of the composite material is greatly improved; in addition, the vacuum treatment time is 300-720 min, the mechanical scraping coating rate is 5-15 cm / min, and the substrate can be a smooth glass substrate.

[0054] S4: The polybenzimidazole / polyether amide acid composite film is dried at 80°C for 300-600 min to remove unreacted solvent N-methyl-2-pyrrolidone, and then imidization treatment is performed, in which the temperature is raised to the glass transition temperature of the polyetherimide, and finally the polybenzimidazole / polyetherimide composite film dielectric is prepared by natural cooling to room temperature, and the structural formula is as shown in Figure 2 The imidization treatment process is as follows: the temperature raising rate is 1.5-2°C / min, and gradient temperature raising treatment is performed in 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-benzenetetramine tetrahydrochloride and trimesic acid are mixed, and then ultrasonically dispersed to obtain a uniform mixed solution. NMP, as a solvent, plays a role in dissolving reactants and promoting uniform mixing of reactants during the reaction process, and 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 the mixture is stirred and reacted in an ice-water bath under the protection of an inert atmosphere to obtain a polybenzimidazole / polyether amic acid composite colloid. In the reaction system, trimesic acid can react with 1,2,4,5-benzenetetramine tetrahydrochloride to generate polybenzimidazole (PBI), and promote the growth and polymerization of polybenzimidazole chain segments to form a stable polybenzimidazole. 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 achieving synchronous polymerization and mutual cross-linking of the polyetheramic acid and polybenzimidazole. During 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 that 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 film-formed polybenzimidazole / polyetheramic acid colloid 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 thin film dielectric prepared by the above method, wherein the mass ratio of polybenzimidazole to polyetherimide in the composite thin film dielectric is (0.1-0.5):100. The present invention prepares the polybenzimidazole / polyetherimide composite thin film by introducing a small amount of polybenzimidazole linking polymer. The polybenzimidazole linking polymer has excellent thermal stability, chemical stability, high specific surface area, and dielectric properties. The introduction of the polybenzimidazole linking polymer improves the energy storage performance of the film while enhancing its stability at high temperatures. The chain structure of the polybenzimidazole / polyetherimide molecules is tightly arranged and bonded, effectively reducing free volume, reducing structural defects, significantly increasing the breakdown field strength of the polymer, improving the polarization strength of the composite material, and avoiding electric field distortion caused by the mismatch between 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 crosslinking region formed between the polybenzimidazole and the polyetherimide significantly improves the inter-chain molecular force of the composite material, strengthens the breakdown field strength of the composite material while inhibiting dielectric loss. That is, the polybenzimidazole / polyetherimide composite film is prepared by adding the polybenzimidazole into the polyether amide acid through the mild and simple simultaneous polymerization process combined with the gradient imidization process, thereby solving the problem of low polarization strength of the polyetherimide. The prepared polybenzimidazole / polyetherimide composite film is dense and defect-free, and the crosslinking effect of the polybenzimidazole and the polyetherimide realizes the organic composite film material with good matching inside and outside. Compared with the existing technology, the polarization strength of the composite material can be improved by adding a small amount of polybenzimidazole, the electric field distortion caused by the mismatch of the dielectric constant and the electrical conductivity between the doped filler and the matrix is effectively avoided, the breakdown field strength of the polybenzimidazole / polyetherimide composite material is improved, and the energy storage density of the composite film material is improved. At the same time, the polybenzimidazole / polyetherimide composite film material exhibits excellent energy storage properties under high temperature conditions.

[0057] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content of the application, and these equivalent forms also fall within the scope of the appended claims of the application.

[0058] The following examples use conventional apparatus in the art. The experimental methods in the following examples are not specified, and are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following examples, unless otherwise specified, and conventional commercially available products are used, which are conventional specifications in the art. In the specification of the application and the following examples, unless otherwise specified, “%” means weight percent, “parts” means weight parts, and the ratio means weight ratio.

[0059] Example 1

[0060] A preparation method of a polybenzimidazole / polyetherimide composite film dielectric, comprising the following steps:

[0061] Step 1: Preparation of polybenzimidazole / polyether amide acid composite colloid: 31.434 g of N-methyl-2-pyrrolidone, 1.500 g of 4,4-diamino diphenyl ether, 0.00774 g of triformylphloroglucinol and 0.02035 g of 1,2,4,5-benzene tetramine tetrahydrochloride were mixed in a three-necked flask, and a uniform organic solution was obtained by ultrasonic dispersion treatment at a frequency of 5000 Hz for 3 min, and argon was introduced. Stirring in an ice water bath, 4.019 g of bisphenol A dianhydride was added to the mixed solution in batches of 1.000 g, 1.000 g, 1.000 g, 0.500 g, 0.200 g, 0.200 g and 0.119 g, wherein the addition time interval of 1.000 g and 0.500 g is 30 min, the addition time interval of 0.200 g and 0.119 g is 10 min, and the stirring is continued for 30 min after the addition is completed, to obtain a polybenzimidazole / polyether amide acid composite colloid.

[0062] Step 2: Preparation of polybenzimidazole / polyether amide acid composite film: The polybenzimidazole / polyether amide acid composite colloid was subjected to vacuum extraction at 0.1 MPa to remove bubbles and a small amount of unreacted solvent at room temperature for 300 min. The treated composite colloid was coated on a smooth glass substrate, and a 15 μm film was obtained by precision mechanical blade coating at a coating rate of 15 cm / min to obtain a polybenzimidazole / polyether amide acid composite film.

[0063] Step 3: Preparation of polybenzimidazole / polyether imide composite film: The polybenzimidazole / polyether amide acid composite film was placed in a precision high-temperature drying oven at 80°C for drying, and the drying time was 300 min. The film was subjected to gradient temperature imidization at 150°C, 200°C, 250°C and 300°C, respectively, and the treatment time at each temperature was 1 h. Then the film was cooled to room temperature to obtain a polybenzimidazole / polyether imide composite film.

[0064] The polybenzimidazole / polyether imide composite film prepared in the application was plated with gold 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 / polyether imide film capacitor prepared in this embodiment has a maximum discharge energy density of 0.174 J / cm 3 .

[0065] Example 2

[0066] A method for preparing a polybenzimidazole / polyether imide composite film dielectric, comprising the following steps:

[0067] Step 1: Preparation of polybenzimidazole / polyether amide acid composite colloid: 31.434 g of N-methyl-2-pyrrolidone, 1.500 g of 4,4-diamino diphenyl ether, 0.00774 g of triformylphloroglucinol and 0.02035 g of 1,2,4,5-benzene tetramine tetrahydrochloride were mixed in a three-necked flask, and a uniform organic solution was obtained by ultrasonic dispersion treatment at a frequency of 1000 Hz for 3 min, and argon was introduced. Stirring in an ice water bath, 4.019 g of bisphenol A dianhydride was added in 1.000 g, 1.000 g, 1.000 g, 0.500 g, 0.200 g, 0.200 g and 0.119 g, respectively, and reacted with the mixed solution, wherein the addition time interval of 1.000 g and 0.500 g is 30 min, the addition time interval of 0.200 g and 0.119 g is 10 min, and after the addition is completed, the stirring is continued for 30 min, to obtain a polybenzimidazole / polyether amide acid composite colloid.

[0068] Step 2: Preparation of polybenzimidazole / polyether amide acid composite film: the polybenzimidazole / polyether amide acid composite colloid was subjected to vacuum extraction at 0.1 MPa at room temperature to remove bubbles and a small amount of unreacted solvent in the composite colloid, and the treatment was completed for 300 min. The treated composite colloid was coated on a smooth glass substrate, and a precision mechanical blade coating technique was used to coat a 15 μm film at a coating rate of 15 cm / min to obtain a polybenzimidazole / polyether amide acid composite film.

[0069] Step 3: Preparation of polybenzimidazole / polyether imide composite film: the polybenzimidazole / polyether amide acid composite film was placed in a precision high-temperature drying oven at 80℃ for drying, and the drying time was 300 min. The imidization was carried out at a gradient temperature of 150℃, 200℃, 250℃ and 300℃, respectively, and the treatment time at each temperature was 1 h. Then, the polybenzimidazole / polyether imide composite film was cooled to room temperature.

[0070] The polybenzimidazole / polyether imide composite film prepared in the application was plated with gold in a vacuum gold plating instrument with a diameter of 0.3 cm, and the dielectric properties and energy storage density were tested. The polybenzimidazole / polyether imide film capacitor prepared in this embodiment has a maximum discharge energy density of 0.429 J / cm 3 .

[0071] Example 3:

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

[0073] Step 1: Preparation of polybenzimidazole / polyether amide acid composite colloid: 31.434 g of N-methyl-2-pyrrolidone, 1.500 g of 4,4-diamino diphenyl ether, 0.00774 g of triformylphloroglucinol and 0.02035 g of 1,2,4,5-benzene tetramine tetrahydrochloride were mixed in a three-necked flask, and a uniform organic solution was obtained by ultrasonic dispersion treatment at a frequency of 3000 Hz for 1 min, and argon was introduced. Stir in an ice water bath, 4.019 g of bisphenol A dianhydride was added in 1.000 g, 1.000 g, 1.000 g, 0.500 g, 0.200 g, 0.200 g and 0.119 g, respectively, and reacted with the mixed solution, wherein 1.000 g and 0.500 g were added at an interval of 30 min, and 0.200 g and 0.119 g were added at an interval of 10 min, and stirring was continued for 60 min after addition, to obtain a polybenzimidazole / polyether amide acid composite colloid.

[0074] Step 2: Preparation of polybenzimidazole / polyether amide acid composite film: The polybenzimidazole / polyether amide acid composite colloid was subjected to vacuum extraction at 0.1 MPa to remove bubbles and a small amount of unreacted solvent in the composite colloid at room temperature for 300 min. The treated composite colloid was coated on a smooth glass substrate, and a 15 μm film was obtained by precision mechanical blade coating at a coating rate of 15 cm / min to obtain a polybenzimidazole / polyether amide acid composite film.

[0075] Step 3: Preparation of polybenzimidazole / polyether imide composite film: The polybenzimidazole / polyether amide acid composite film was placed in a precision high-temperature drying oven at 80°C for drying, and the drying time was 300 min. The film was subjected to gradient temperature imidization at 150°C, 200°C, 250°C and 300°C, respectively, and the treatment time at each temperature was 1 h. Then, the film was cooled to room temperature to obtain a polybenzimidazole / polyether imide composite film.

[0076] The polybenzimidazole / polyether imide composite film prepared in the application was plated with gold 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 / polyether imide film capacitor prepared in this example had a maximum discharge energy density of 1.503 J / cm 3 .

[0077] Example 4

[0078] The difference between this example and Example 3 is that the time for vacuum extraction of bubbles and a small amount of unreacted solvent in the composite colloid in Step 2 is 460 min. The polybenzimidazole / polyether imide film capacitor prepared in this example had a maximum discharge energy density of 1.370 J / cm 3 .

[0079] Example 5

[0080] The difference between this example and Example 3 is that in Step 2, the bubbles in the composite colloid and a small amount of incompletely reacted solvent are removed by vacuum extraction for 720 min. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 1.441 J / cm 3 .

[0081] Example 6

[0082] The difference between this example and Example 5 is that in Step 2, the 8 μm thin film is prepared by precision mechanical blade coating at a blade coating rate of 5 cm / min. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 1.023 J / cm 3 .

[0083] Example 7

[0084] The difference between this example and Example 5 is that in Step 2, the 13 μm thin film is prepared by precision mechanical blade coating at a blade coating rate of 10 cm / min. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 2.065 J / cm 3 .

[0085] Example 8

[0086] The difference between this example and Example 7 is that in Step 3, the polybenzimidazole / polyetherimide acid composite thin film is dried in a precision high temperature drying oven at 80°C for 450 min. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 2.071 J / cm 3 .

[0087] Example 9

[0088] The difference between this example and Example 7 is that in Step 3, the polybenzimidazole / polyetherimide acid composite thin film is dried in a precision high temperature drying oven at 80°C for 600 min. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 2.528 J / cm 3 .

[0089] Example 10

[0090] The difference between this example and Example 9 is that 0.003096 g of trimesic aldehyde and 0.008138 g of 1,2,4,5-benzene tetramine tetrahydrochloride are used in Step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 3.062 J / cm2at a field strength of 440 kV / mm 3 .

[0091] Example 11

[0092] The difference between this example and Example 9 is that 0.001548 g of trimesic aldehyde and 0.004069 g of 1,2,4,5-benzene tetramine tetrahydrochloride are used in Step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 4.140 J / cm2at a field strength of 520 kV / mm 3 .

[0093] Example 12

[0094] The difference between this example and Example 9 is that the mass ratio of 4,4-diamino diphenyl ether to N-methyl-2-pyrrolidone is 1:12 in Step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 2.528 J / cm2at a field strength of 400 kV / mm 3 .

[0095] Example 13

[0096] The difference between this example and Example 9 is that the mass ratio of 4,4-diamino diphenyl ether to N-methyl-2-pyrrolidone is 1:16 in Step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 1.888 J / cm2at a field strength of 500 kV / mm 3 .

[0097] Example 14

[0098] The difference between this example and Example 9 is that the mass ratio of 4,4-diamino diphenyl ether to N-methyl-2-pyrrolidone is 1:14 in Step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 5.668 J / cm2at a field strength of 540 kV / mm 3 .

[0099] Example 15

[0100] The difference between this example and example 13 is that 0.00774 g of trimesic aldehyde and 0.02035 g of 1,2,4,5-benzene tetramine tetrahydrochloride are used in step 1 of step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 5.351 J / cm2 at a field strength of 600 kV / mm 3 .

[0101] Example 16

[0102] The difference between this example and example 15 is that 0.003096 g of trimesic aldehyde and 0.008138 g of 1,2,4,5-benzene tetramine tetrahydrochloride are used in step 1 of step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 3.236 J / cm2 at a field strength of 500 kV / mm 3 .

[0103] Example 17

[0104] The difference between this example and example 15 is that 0.001548 g of trimesic aldehyde and 0.004069 g of 1,2,4,5-benzene tetramine tetrahydrochloride are used in step 1 of step 1. The polybenzimidazole / polyetherimide thin film capacitor prepared in this example has a maximum discharge energy density of 7.258 J / cm2 at a field strength of 620 kV / mm 3 .

[0105] Figure 3 The Fourier infrared absorption spectrum of the polybenzimidazole / polyetherimide prepared in examples 15, 16 and 17 of the present application and the pure polyetherimide composite thin film dielectric, as can be seen from the figure, at 2100-2400 cm -1 , the prepared composite material appears an absorption peak of the cumulative double bond region compared with polyetherimide, the formation of the special structure of polybenzimidazole / polyetherimide will cause the stacking of C=N double bond and C=O double bond, thus forming such peak, indicating the successful preparation of polybenzimidazole / polyetherimide composite thin film dielectric.

[0106] Figure 4 The insulation performance Weibull distribution statistical comparison chart of the polybenzimidazole / polyetherimide prepared in examples 15, 16 and 17 of the present application and the pure polyetherimide composite thin film dielectric, compared with polyetherimide, the insulation performance of each component polybenzimidazole / polyetherimide composite thin film dielectric is obviously improved.

[0107] Figure 5A comparison chart of the 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 application and the pure polyetherimide composite thin film dielectric, at 25℃, 0.1wt% polybenzimidazole / polyetherimide composite thin film dielectric obtained 4.7Jcm -3 of discharge energy density at an energy storage efficiency of more than 90%, higher than 3.2J cm -3 of polyetherimide at the same temperature, and still has 7.258J cm -1 of discharge energy density at a breakdown field strength of 620kV mm -3 , an increase of 126.5% in energy density at the breakdown field strength compared with the original PEI.

[0108] Example 18

[0109] A preparation method of a polybenzimidazole / polyetherimide composite thin film dielectric, comprising the following steps:

[0110] S1: mixing N-methyl-2-pyrrolidone, 4,4-diamino diphenyl ether, 1,2,4,5-benzene tetraamine tetrahydrochloride and trimesaldehyde, and then ultrasonic dispersion for 3min at a frequency of 1000Hz to obtain a uniform mixed solution;

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

[0112] S3: vacuum treatment of the polybenzimidazole / polyetherimide acid composite colloid at room temperature for 300min to remove bubbles and a small amount of unreacted solvent in the composite colloid, and then using the polybenzimidazole / polyetherimide acid composite colloid to prepare a polybenzimidazole / polyetherimide acid composite film; the thickness of the polybenzimidazole / polyetherimide acid composite film is 8μm.

[0113] S4: The polybenzimidazole / polyetherimide acid composite film is dried at 80°C for 300 min to remove unreacted solvent N-methyl-2-pyrrolidone, and then subjected to imidization treatment, in which 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 as follows: the temperature is raised at a rate of 1.5°C / min, and gradient temperature raising is performed in the range of 100°C.

[0114] Example 19

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

[0116] S1: N-methyl-2-pyrrolidone, 4,4-diamino diphenyl ether, 1,2,4,5-benzene tetraamine tetrahydrochloride and trimesaldehyde are mixed and ultrasonically dispersed at a frequency of 5000 Hz for 1 min to obtain a uniform mixed solution;

[0117] S2: Bisphenol A dianhydride is added to the mixed solution in batches, and stirring reaction is performed in an ice water bath at 10°C under the protection of argon atmosphere to obtain a polybenzimidazole / polyetherimide acid composite colloid; wherein the mass ratio of 4,4-diamino diphenyl ether to N-methyl-2-pyrrolidone is 1:21; the mass ratio of trimesaldehyde to 1,2,4,5-benzene tetraamine tetrahydrochloride is 1:2.8; the mass ratio of 4,4-diamino diphenyl ether to bisphenol A dianhydride is 1:2.8; and the total mass ratio of trimesaldehyde and 1,2,4,5-benzene tetraamine tetrahydrochloride to the total mass of 4,4-diamino diphenyl ether and bisphenol A dianhydride is 0.5:100.

[0118] S3: The polybenzimidazole / polyetherimide acid composite colloid is subjected to vacuum treatment at room temperature for 720 min to remove bubbles and a small amount of unreacted solvent in the composite colloid, and then the polybenzimidazole / polyetherimide acid composite film is prepared using the polybenzimidazole / polyetherimide acid composite colloid; the thickness of the polybenzimidazole / polyetherimide acid composite film is 15 μm.

[0119] S4: The polybenzimidazole / polyetherimide acid composite film is dried at 80°C for 600 min to remove unreacted solvent N-methyl-2-pyrrolidone, and then subjected to imidization treatment, in which 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 as follows: the temperature is raised at a rate of 2°C / min, and gradient temperature raising is performed in the range of 300°C.

[0120] Example 20

[0121] A preparation method of a polybenzimidazole / polyetherimide composite thin film dielectric, comprising the following steps:

[0122] S1: mixing N-methyl-2-pyrrolidone, 4,4-diamino diphenyl ether, 1,2,4,5-benzene tetramine tetrahydrochloride and trimesaldehyde, and then ultrasonic dispersion for 2 min at a frequency of 3000 Hz to obtain a uniform mixed solution;

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

[0124] S3: vacuum treatment of the polybenzimidazole / polyether amide acid composite colloid at room temperature for 500 min to remove bubbles and a small amount of unreacted solvent in the composite colloid, and then using the polybenzimidazole / polyether amide acid composite colloid to prepare a polybenzimidazole / polyether amide acid composite film; the thickness of the polybenzimidazole / polyether amide acid composite film is 10 μm.

[0125] S4: drying the polybenzimidazole / polyether amide acid composite film at 80 DEG C for 400 min to remove unreacted solvent N-methyl-2-pyrrolidone, and then carrying out imidization treatment; in the imidization treatment process, the temperature is raised to the glass transition temperature of polyetherimide, and finally naturally cooled to room temperature to obtain the polybenzimidazole / polyetherimide composite thin film dielectric; the imidization treatment process specifically comprises: gradient temperature raising treatment at a temperature raising rate of 1.8 DEG C / min in the range of 200 DEG C.

[0126] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

[0127] Finally, it should be noted that the above examples are merely intended to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

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 inert atmosphere to react to obtain a polybenzimidazole / polyether amic acid composite colloid; S3: preparing a polybenzimidazole / polyetheramic acid composite film using the polybenzimidazole / polyetheramic acid composite colloid; S4: performing imidization treatment on the polybenzimidazole / polyetheramic acid composite film to obtain the polybenzimidazole / polyetherimide composite film dielectric; 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 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.

2. 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.

3. 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.

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

5. 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 temperature is increased at a rate of 1.5-2°C / min, and the temperature is increased gradually within the range of 100-300°C.

6. A polybenzimidazole / polyetherimide composite thin film dielectric, characterized in that: Prepared by the method according to any one of claims 1 to 5.

7. The polybenzimidazole / polyetherimide composite thin film dielectric according to claim 6, characterized in that: In the composite thin film dielectric, the mass ratio of polybenzimidazole to polyetherimide is (0.1-0.5):

100.

8. Use of the polybenzimidazole / polyetherimide composite film dielectric according to any one of claims 6 to 7 in a polymer-based film capacitor.

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