A high-voltage composite dielectric insulating film and its preparation method and application

Abstract

The present invention discloses a high-voltage-resistant composite dielectric insulating film, its preparation method and application, belonging to the technical field of dielectric capacitors. The present invention solves the problems of poor breakdown performance and large dielectric loss of existing dielectric insulating films. First, the present invention synthesizes a metal-organic cluster Ce@Al with Ce(Ⅲ) as the core and Al as the shell, and dopes an appropriate amount in a polyetherimide (PEI) matrix. The present invention utilizes the fact that the metal-organic cluster Ce@Al and the polyetherimide dielectric can be highly mixed. The phenyl groups on the periphery of the cluster endow it with good stability, and the electrostatic repulsion between the Ce@Al cation clusters ensures the uniform distribution of Ce@Al in the dielectric. In addition, the trivalent ions in the Ce@Al structure synthesized by the present invention provide a high dipole moment and have strong charge scattering and trapping capabilities, which can effectively inhibit the movement of charges inside the dielectric and achieve a significant improvement in the insulating performance of the composite dielectric.

Description

Technical Field

[0001] The present invention relates to a high-voltage composite dielectric insulating film, a preparation method thereof and an application thereof, belonging to the technical field of dielectric capacitors. Background Art

[0002] Due to the unique advantage of high power density, dielectric capacitors are widely used in fast charge and discharge fields such as high-power pulse power supplies, hybrid electric vehicles, and electromagnetic weapons. Among them, polymer capacitors have attracted wide attention due to their advantages such as easy processing, good stability, high breakdown strength, and wide capacitance range. With the expansion of the application fields of polymer capacitors, the requirements for insulation breakdown are getting higher and higher. This means that it is urgent to develop a polymer capacitor with high insulation breakdown, and whether a high-voltage composite dielectric insulating film can be prepared plays a decisive role in the performance of the polymer capacitor. Therefore, it is very necessary to provide a high-voltage composite dielectric insulating film and a preparation method thereof. Summary of the Invention

[0003] Aiming at the problems of poor breakdown performance and large dielectric loss of the existing dielectric insulating film, the present invention provides a high-voltage composite dielectric insulating film, a preparation method thereof and an application thereof.

[0004] The technical solution of the present invention:

[0005] One of the purposes of the present invention is to provide a preparation method of a high-voltage composite dielectric insulating film, and the method specifically includes the following steps:

[0006] Step 1, mix acetonitrile, aluminum isopropoxide, ammonium cerium nitrate, cerium(III) nitrate hexahydrate and 3-aminobenzoic acid, heat and stir under sealed conditions, then drop in pyridine and nitric acid, and continue to stir under sealed conditions after dropping to obtain a reaction solution containing white precipitate;

[0007] Step 2, transfer the reaction solution containing white precipitate obtained in Step 1 to an oven and place it to obtain a solution containing wine-red Ce@Al crystals, wash by centrifugation with acetone to obtain Ce@Al crystals, dry, and seal for standby;

[0008] Step 3, grind the Ce@Al crystals into powder, dissolve them in NMP solvent, filter, add PEI particles, heat and stir until the PEI particles are dissolved to obtain a PEI solution doped with Ce@Al;

[0009] Step 4, perform defoaming treatment on the PEI solution doped with Ce@Al, then coat the film to obtain a wet film, and dry it to obtain a high-voltage composite dielectric insulating film.

[0010] Further defined, in step 1, the mass-volume ratio of acetonitrile, aluminum isopropoxide, ammonium cerium nitrate, cerium(III) nitrate hexahydrate, 3-aminobenzoic acid, pyridine and nitric acid is 50 mL: 0.153 g: 0.046 g: 0.145 g: 0.06 g: 2 mL: 50 μL.

[0011] Further defined, in step 1, the purity of acetonitrile is 99%, the purity of aluminum isopropoxide ≥ 98%, the purity of ammonium cerium nitrate is 98%, the purity of cerium(III) nitrate hexahydrate is 99.5%, the purity of 3-aminobenzoic acid is 98%, the purity of pyridine is ≥ 99%, and the purity of nitric acid is 16%.

[0012] Further defined, in step 1, the heating and stirring temperature under sealed conditions is 80 °C.

[0013] Even further defined, in step 1, acetonitrile, aluminum isopropoxide, ammonium cerium nitrate, cerium(III) nitrate hexahydrate and 3-aminobenzoic acid are mixed, and the heating and stirring time under sealed conditions is 15 min.

[0014] Even further defined, in step 1, after the dropping of pyridine and nitric acid is completed, the heating and stirring time under sealed conditions is 240 min.

[0015] Further defined, in step 2, the reaction solution containing white precipitate is placed in an oven at 80 °C for 7 d.

[0016] Further defined, in step 2, the number of centrifugal washing times is 5, the rotation speed each time is 800 r / min, and the time is 5 - 8 min; the drying temperature is 60 °C and the time is 12 h.

[0017] Further defined, Ce@Al is [Al 8 Ce(μ 2- OH) 8 (μ 3 -OH) 8 (BA-mNH 2 ) 8 (H 2 O)]·3NO 3 , with a structure of a Ce-Al-O macrocycle, which contains a Ce(Ⅲ) core and is connected to 8 peripheral Al atoms through 16 bridging hydroxyl groups and 8 3-aminophenyl groups.

[0018] Further defined, in step 3, the mass of the Ce@Al crystal is 1 - 10% of the mass of PEI.

[0019] Further defined, in step 3, the dissolution temperature is 60 °C.

[0020] Further defined, in step 4, the wet film thickness is 5 - 10 μm.

[0021] Further limitation: In step 4, drying is carried out by a drying tunnel, and the drying process is as follows: drying at 80°C for 4 hours with a relative humidity of 40%-50%; drying at 100°C for 2 hours with a relative humidity of 30%-40%; drying at 150°C for 2 hours with a relative humidity of 20%-30%; vacuum drying at 200°C for 2 hours with a relative humidity of 10%-20%; the exhaust air volume in the drying tunnel controls the solvent vapor concentration to be 0.01%-0.8%.

[0022] Further limitation: After the wet film is dried in step 4, it is subjected to immersion dust removal treatment.

[0023] Even further limitation: The process of immersion dust removal treatment is as follows: After the film is cooled to room temperature, it is immersed in deionized water for continuous immersion treatment, and then immersed in alcohol for ultrasonic treatment to clean dust. The cleaning and dust removal time is 5-10 minutes, the immersion treatment time is 45-60 minutes. After obtaining the film, it is ultrasonically treated with deionized water for 30 minutes, and finally dried at 70°C for 12 hours.

[0024] The second object of the present invention is to provide a high-voltage-resistant composite dielectric insulating film prepared by the above method.

[0025] The third object of the present invention is to provide an application of the above high-voltage-resistant composite dielectric insulating film, specifically for the preparation of dielectric capacitors.

[0026] Beneficial effects:

[0027] In the present invention, polyetherimide (PEI) with excellent electrical insulation performance, mechanical properties and high and low temperature resistance is used as the matrix, and metal-organic cluster (Ce@Al) is prepared. By doping Ce@Al, the insulation performance of polyetherimide is improved. Compared with the prior art, the present application has the following advantages:

[0028] (1) In the present invention, the metal-organic cluster Ce@Al and the polyetherimide medium can be highly mixed. The phenyl groups on the periphery of the cluster endow it with good stability, and the electrostatic repulsion between the Ce@Al cation clusters ensures the uniform distribution of Ce@Al in the medium. In addition, the trivalent ions in the Ce@Al structure synthesized in the present invention provide a high dipole moment and have strong charge scattering and trapping capabilities, which can effectively inhibit the movement of charges inside the medium and achieve a substantial improvement in the insulation performance of the composite medium.

[0029] (2) The Ce@Al prepared by the present invention has a single and stable molecular cluster, which can equivalently regard Ce@Al and the doped dielectric as a series connection of a capacitor and a resistor, and the capacitance value can be calculated according to the size of the synthesized Ce@Al. Therefore, through certain calculations, the optimal doping ratio in the preparation of the experimental film can be directly calculated, thereby reducing unnecessary waste in the film preparation during the production process and lowering the production cost.

[0030] (3) The doping and modification process of polyetherimide provided by the present invention is simple, stable and reliable, and the preparation process is safe. It is suitable for preparing large-area films and is conducive to realizing industrial production. Description of the Drawings

[0031] Figure 1 It is the Weibull distribution diagram of the breakdown field strength of the dielectric films prepared in Examples 1-5 and Comparative Example 1;

[0032] Figure 2 It is the curve diagram of the dielectric constant of the dielectric films prepared in Examples 1-5 and Comparative Example 1 changing with frequency;

[0033] Figure 3 It is the XRD comparison pattern of the dielectric films prepared in Examples 1-5 and Comparative Example 1;

[0034] Figure 4 It is the infrared spectrum comparison diagram of the dielectric films prepared in Examples 1-5 and Comparative Example 1;

[0035] Figure 5 It is the scanning electron microscope image of the dielectric films prepared in Examples 1-5 and Comparative Example 1, where (a) is PEI, (b) is 1wt%-Ce@Al / PEI, (c) is 3wt%-Ce@Al / PEI, (d) is 5wt%-Ce@Al / PEI, (e) is 10wt%-Ce@Al / PEI, and (f) is 20wt%-Ce@Al / PEI. Detailed Embodiments

[0036] To make the above objects, features and advantages of the present invention more obvious and understandable, the following describes the specific embodiments of the present invention in detail with reference to the embodiments of the specification.

[0037] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0038] Second, the "one embodiment" or "embodiment" referred to herein means a specific feature, structure or characteristic that may be included in at least one implementation manner of the present invention. The "in one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0039] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods. The materials, reagents, methods and instruments used, unless otherwise specified, are all conventional materials, reagents, methods and instruments in this field. Those skilled in the art can obtain them through commercial channels, and the purities of the solid and liquid reagents used are all analytical pure.

[0040] Example 1

[0041] (1) Preparation process of metal-organic cluster Ce@Al:

[0042] Step 1: Load 50 mL of acetonitrile into a blue-capped reagent bottle, and then sequentially add 0.153 g of aluminum isopropoxide, 0.046 g of ammonium cerium nitrate, 0.145 g of cerium(III) nitrate hexahydrate, and 0.06 g of 3-aminobenzoic acid (BA-mNH 2 ), seal and heat at 80 °C and stir for 15 min.

[0043] Step 2: Sequentially drop in 2 mL of pyridine and 50 μL of nitric acid, seal and magnetically stir at 80 °C for 240 min, and then a white precipitate appears.

[0044] Step 3: After the stirring is completed, transfer it to an oven at 80 °C and place it for 7 days. Wine-red Ce@Al crystals appear. Clean the Ce@Al with acetone by centrifugation 5 times. The centrifugation speed of the centrifuge is 800 r / min and the time is 8 min. Place the cleaned crystals in an oven at 60 °C for 12 h and store them in a sealed and dry environment.

[0045] Among them, the purity of acetonitrile is 99%, the purity of aluminum isopropoxide ≥ 98%, the purity of ammonium cerium nitrate is 98%; the purity of cerium(III) nitrate hexahydrate is 99.5%, the purity of 3-aminobenzoic acid is 98%, the purity of pyridine is ≥ 99%, and the purity of nitric acid is 16%.

[0046] (2) Preparation process of PEI-modified dielectric film with 1 wt% Ce@Al doping:

[0047] Step 1: Grind 0.016 g of Ce@Al crystals into powder, place them in 10 mL of NMP solvent, heat and stir at 60 °C for 30 min to dissolve, filter, add 1.6 g of PEI particles, heat at 60 °C, rotate at 200 r / min, and stir for 12 h until the PEI particles dissolve.

[0048] Step 2: Defoam the solution from Step 1 at 60 °C under vacuum, and coat a film using a coater with a film thickness of 8 μm. Immediately after coating, transfer it to a drying oven with controlled humidity and ventilation volume for drying treatments at 80 °C for 4 h, 150 °C for 2 h, and 200 °C under vacuum for 2 h.

[0049] Step 3: Take out the film from the oven, cool it to room temperature, then immerse it in deionized water for continuous soaking treatment. Subsequently, immerse it in alcohol for ultrasonic cleaning to remove dust. The dust cleaning time is 5 min, the soaking treatment time is 60 min. After obtaining the film, perform ultrasonic treatment with deionized water for 30 min, and finally dry it at 70 °C for 12 h to obtain a PEI-modified dielectric film with a Ce@Al doping amount of 1 wt%, named 1 wt%-Ce@Al / PEI.

[0050] Example 2

[0051] The difference between this example and Example 1 is that in Step 1 of (2), the Ce@Al crystal is 0.048 g, and the remaining process steps and parameter settings are the same as those in Example 1, obtaining a PEI-modified dielectric film with a Ce@Al doping amount of 3 wt%, named 3 wt%-Ce@Al / PEI.

[0052] Example 3

[0053] The difference between this example and Example 1 is that in Step 1 of (2), the Ce@Al crystal is 0.08 g, and the remaining process steps and parameter settings are the same as those in Example 1, obtaining a PEI-modified dielectric film with a Ce@Al doping amount of 5 wt%, named 5 wt%-Ce@Al / PEI.

[0054] Example 4

[0055] The difference between this example and Example 1 is that in Step 1 of (2), the Ce@Al crystal is 0.16 g, and the remaining process steps and parameter settings are the same as those in Example 1, obtaining a PEI-modified dielectric film with a Ce@Al doping amount of 10 wt%, named 10 wt%-Ce@Al / PEI.

[0056] Example 5

[0057] The difference between this example and Example 1 is that in Step 1 of (2), the Ce@Al crystal is 0.32 g, and the remaining process steps and parameter settings are the same as those in Example 1, obtaining a PEI-modified dielectric film with a Ce@Al doping amount of 20 wt%, named 20 wt%-Ce@Al / PEI.

[0058] Comparative Example 1

[0059] Step 1: Add 1.6 g of PEI particles into 10 mL of NMP solvent, heat at 60 °C with a rotation speed of 300 r / min, and stir for 12 h until the PEI particles are dissolved.

[0060] Step 2: Debubble the PEI solution under vacuum at 60 °C, and coat the film using a coater with a film thickness of 8 μm. Immediately after coating, transfer it to a drying oven with controlled humidity and ventilation volume for drying treatments at 80 °C for 4 h, 150 °C for 2 h, and 200 °C under vacuum for 2 h.

[0061] Step 3: Take out the film from the oven, cool it to room temperature, immerse it in deionized water for continuous soaking treatment, then immerse it in alcohol for ultrasonic cleaning to remove dust. The dust cleaning time is 10 min, the soaking treatment time is 60 min. After obtaining the film, perform ultrasonic treatment in deionized water for 30 min, and finally dry it at 70 °C for 12 h to obtain the dielectric film named PEI.

[0062] Effect Example

[0063] (1) Characterize the breakdown field strength of the dielectric films prepared in Examples 1 - 5 and Comparative Example 1. The results are as Figure 1 shown. It can be seen from Figure 1 that as the content of Ce@Al increases, the breakdown field strength of the dielectric continuously increases, reaching a maximum value of 703 MV / m at the composition of 3 wt% - Ce@Al / PEI. This is because Ce@Al has strong charge scattering and trapping capabilities, which can effectively inhibit the movement of charges inside the dielectric and achieve a significant improvement in the insulation performance of the composite dielectric. However, as the content of Ce@Al continues to increase, the dielectric loss increases, resulting in a sharp decrease in the breakdown strength. The breakdown strength of 20% Ce@Al - PEI reaches the lowest.

[0064] (2) Figure 2 shows the dielectric constant and dielectric loss graphs of the dielectric films prepared in Examples 1 - 5 and Comparative Example 1. It can be seen from Figure 2 that as the content of Ce@Al increases, the dielectric constant continuously increases, reaching a maximum value of 7 at the composition of 20% Ce@Al - PEI. The dielectric loss is the lowest at 3% Ce@Al - PEI, and it continuously increases as the content increases.

[0065] (3) Figure 3 shows the XRD graphs of the dielectric films prepared in Examples 1 - 5 and Comparative Example 1. It can be seen from Figure 3 that as the content of Ce@Al increases, the diffraction peak at low angles is enhanced.

[0066] (4) Figure 4 shows the infrared spectra of the dielectric films prepared in Examples 1 - 5 and Comparative Example 1. It can be seen from Figure 4It can be seen that in the high wavenumber region ν>1000 cm -1 , the weak absorption band at 3690 - 3000 cm -1 can be attributed to the stretching vibration of the O-H bond in the hydroxyl and amino functional groups. The (CO 2 2- ) in the carboxyl group and (C=C) in the benzene ring overlap between 1650~1405 cm -1 . The infrared peak at 1477 - 1374 cm -1 is (CO 2 2- ). In addition, the stretching vibration peak and deformation vibration of NO 3 - appear at 1368 - 1293 cm -1 and 865 - 841 cm -1 respectively. In the infrared spectrum, the presence of NO 3 and functional groups such as hydroxyl and amino groups indicates that Ce@Al is effectively doped into PEI without changing the chemical structure of PEI.

[0067] (5) Figure 5 FIG. 5 is a scanning electron micrograph of the dielectric films prepared in Examples 1 - 5 and Comparative Example 1, where (a) is PEI, (b) is 1wt%-Ce@Al / PEI, (c) is 3wt%-Ce@Al / PEI, (d) is 5wt%-Ce@Al / PEI, (e) is 10wt%-Ce@Al / PEI, and (f) is 20wt%-Ce@Al / PEI. It can be Figure 5 seen that the cross-section texture of the components doped with Ce@Al is uniform and smooth without obvious defects, indicating that the metal-organic clusters are uniformly dispersed in the medium and no agglomeration occurs even at high doping levels.

[0068] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various modifications and decorations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A method for preparing a high-voltage composite dielectric insulating film, characterized in that: include: Step 1, acetonitrile, aluminum isopropoxide, ammonium cerium nitrate, cerium (III) nitrate hexahydrate and 3-aminobenzoic acid are mixed, heated and stirred under a sealed condition, and then pyridine and nitric acid are dropped into the mixture, and the mixture is continuously stirred under a sealed condition after the dropwise addition is completed to obtain a reaction solution containing a white precipitate; Step 2, transferring the reaction solution containing white precipitate obtained in step 1 into an oven to obtain a solution containing wine red Ce@Al crystals, washing the solution by centrifugation with acetone to obtain Ce@Al crystals, drying the solution, and sealing the solution for later use; Step 3, grinding Ce@Al crystals into powder and dissolving them in NMP solvent, filtering, adding PEI particles, heating and stirring until the PEI particles are dissolved, and obtaining a PEI solution doped with Ce@Al; Step 4, defoaming the PEI solution doped with Ce@Al, coating the solution to obtain a wet film, and drying the film to obtain a composite dielectric insulating film with a high withstand voltage.

2. The preparation method according to claim 1, characterized in that: In step 1, the mass volume ratio of acetonitrile, aluminum isopropoxide, ammonium cerium nitrate, cerium (III) nitrate hexahydrate, 3-aminobenzoic acid, pyridine and nitric acid is 50 mL: 0.153 g: 0.046 g: 0.145 g: 0.06 g: 2 mL: 50 μL; the purity of nitric acid is 16%.

3. The preparation method according to claim 1, characterized in that: In step 1, the heating and stirring temperature under the sealed condition is 80°C.

4. The preparation method according to claim 1, characterized in that: The reaction solution containing white precipitate in step 2 was placed in an oven at 80° C. for 7 days.

5. The preparation method according to claim 1, characterized in that: In step 2, the number of centrifugal washings is 5 times, each time the speed is 800 r / min, the time is 5-8 min; the drying temperature is 60° C., and the time is 12 h.

6. The preparation method according to claim 1, characterized in that: In step 3, the mass of Ce@Al crystals is 1-20% of the mass of PEI.

7. The preparation method according to claim 1, characterized in that: The wet film thickness in step 4 is 5 to 10 μm.

8. The preparation method according to claim 1, characterized in that: In step 4, the drying is carried out by a drying tunnel, and the drying process is as follows: drying at 80°C for 4 hours, and a relative humidity of 40%-50%; drying at 100°C for 2 hours, and a relative humidity of 30%-40%; drying at 150°C for 2 hours, and a relative humidity of 20%-30%; vacuum drying at 200°C for 2 hours, and a relative humidity of 10%-20%; the exhaust air volume in the drying tunnel controls the solvent vapor concentration to be 0.01%-0.8%.

9. A high-voltage composite dielectric insulating film prepared by the method according to any one of claims 1 to 8.

10. An application of the high withstand voltage composite dielectric insulating film according to claim 9, characterized in that: Used in the preparation of dielectric capacitors.

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