A modified polyimide dielectric thin film material, its preparation method, and its application.

Abstract

This application belongs to the field of capacitor technology, and particularly relates to a modified polyimide dielectric film material, its preparation method, and its application. The provided modified polyimide dielectric film material uses polarized modified dianhydride / titanium dioxide nanoparticles to modify the dielectric film material, thereby improving its energy storage characteristics at high temperatures. The film capacitor assembled after being made into a metallized film is suitable as an energy storage device at high temperatures. This solves the technical problem of low performance of polyimide dielectric film materials in the prior art.

Description

Technical Field

[0001] This application belongs to the field of capacitor technology, and particularly relates to a modified polyimide dielectric film material, its preparation method, and its application. Background Technology

[0002] Dielectric capacitors are among the highest power density energy storage devices and are one of the main energy storage technologies in advanced electronic power systems. They have important applications in fields such as electric vehicle inverters and aerospace.

[0003] Dielectric capacitors using different dielectric types, such as ceramic dielectrics and dielectric films, exhibit varying performance. Among dielectric capacitors, film capacitors using dielectric films typically have lower energy density, especially at high temperatures. Due to increased leakage current, the energy density further decreases, making them insufficient to meet the needs of high-power and high-temperature electronic devices and electrical systems. For example, the commercially available benchmark dielectric film material currently used in film capacitors, biaxially oriented polypropylene (BOPP), has a discharge energy density (Ud) of approximately 2 J / cm² at room temperature (200 MV / m). 3 When the operating temperature reaches 105℃, its energy storage performance decreases significantly and losses increase dramatically. Studies have shown that the energy storage density of dielectric films is affected by the dielectric constant (K) and the breakdown field strength (E). b The influence of temperature (Tg) on ​​dielectric films is a concern. For dielectric films to be used at high temperatures (~150℃), the material itself needs to have a high glass transition temperature (Tg). Developing new polymer dielectric film materials that not only have a high glass transition temperature, but also a high dielectric constant and breakdown field strength at high temperatures is of great significance for improving the high-temperature energy storage density of dielectric films.

[0004] Besides biaxially oriented polypropylene (BOPP), polyimide (PI) is also a common dielectric film material for film capacitors. PI has a higher glass transition temperature than BOPP and superior high-temperature resistance. Furthermore, by improving the polarization properties of polyimide (PI) dielectric films, the dielectric constant (K) and breakdown field strength (E) of the polyimide (PI) dielectric film material can be optimized. b To improve the ability of dielectric films to "store charge" under the action of an electric field, the energy storage density of polyimide (PI) dielectric film materials is increased; however, there is currently a lack of effective means to improve the polarization performance of polyimide (PI) dielectric film materials, resulting in the low performance of polyimide (PI) dielectric film materials. Summary of the Invention

[0005] In view of this, this application provides a modified polyimide dielectric film material, its preparation method, and its application, to solve the technical problem of low performance of polyimide dielectric film materials in the prior art.

[0006] The first aspect of this application provides a method for preparing a modified polyimide dielectric thin film material, the method comprising the following steps:

[0007] The steps for preparing polarized modified dianhydride monomers are as follows: 4,4'-thiophthalic anhydride is dissolved in an organic solvent, an oxidizing agent is added to oxidize the thioether structure in 4,4'-thiophthalic anhydride, and the polarized modified dianhydride monomer is obtained after purification.

[0008] The steps for preparing polyamic acid are as follows: polarized modified dianhydride monomer, diamine monomer, high dielectric constant nanoparticles and organic solvent are mixed and polycondensed to obtain a polyamic acid solution doped with titanium oxide nanoparticles.

[0009] The steps for preparing a polyamic acid film include: covering a substrate with a polyamic acid wet film doped with titanium oxide nanoparticles, and evaporating the organic solvent to obtain a modified polyamic acid film;

[0010] The steps for preparing polyimide films are as follows: crosslinking and curing the modified polyamic acid film to obtain the modified polyimide dielectric film material.

[0011] Preferably, in the step of preparing the polarized modified dianhydride monomer, the added oxidant is selected from at least one of m-chloroperoxybenzoic acid, sodium hypochlorite, and hydrogen peroxide;

[0012] The organic solvent used is selected from at least one of chloroform, dichloromethane, and dichloroethane.

[0013] Preferably, in the step of preparing polyamic acid, the diamine monomer used is selected from aromatic diamines such as 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodibenzophenone, m-phenylenediamine, p-phenylenediamine, diaminodiphenylmethane, 2,2'-dimethoxy-4,4'-diaminobenzoyl aniline, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-cyclohexanediamine, ethylenediamine, hexamethylenediamine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 4,4'-diamino-2,2'-difluorobiphenyl, etc.;

[0014] The high dielectric constant nanoparticles used can be selected from nanoparticles with a dielectric constant of not less than 10, such as titanium oxide nanoparticles, zirconium oxide nanoparticles, niobium oxide nanoparticles, lanthanum oxide nanoparticles, hafnium oxide nanoparticles, etc.

[0015] The organic solvent used is selected from at least one of NMP, DMAc, DMF, DMSO, and NEP.

[0016] Preferably, in the step of preparing polarized modified dianhydride monomer, the oxidation reaction temperature is room temperature and the time is 0.5~2h.

[0017] Preferably, in the step of preparing polyamic acid, the polycondensation temperature is room temperature and the time is 5~20h.

[0018] Preferably, in the step of preparing the polyamic acid film, the method of coating the substrate with a polyamic acid wet film doped with titanium oxide nanoparticles is at least one of solution casting, casting, blade coating, dip coating, and spin coating, and the temperature for evaporating the organic solvent is 40~80℃ and the time is 5~20h.

[0019] Preferably, in the step of preparing the polyimide film, the crosslinking and curing process includes: crosslinking and curing at 120~180℃ for 0.5~2h, at 180~220℃ for 0.5~2h, and at 230~270℃ for 0.5~2h in sequence.

[0020] Preferably, in the step of preparing the polyimide film, after cross-linking and curing to obtain the modified polyimide dielectric film material, the step further includes peeling the modified polyimide dielectric film material from the substrate.

[0021] Preferably, in the step of preparing the polarized modified dianhydride monomer, the molar ratio of 4,4'-thiophthalic anhydride and oxidant is 1:1 to 1.2.

[0022] Preferably, in the step of preparing polyamic acid: the molar ratio of the polarized modified dianhydride monomer and the diamine monomer used is 1:1, and the amount of nanoparticles with high dielectric constant added is 0.2~1% of the sum of the mass of the polarized modified dianhydride monomer and the diamine monomer.

[0023] The second aspect of this application provides a modified polyimide dielectric film material, which is prepared by the preparation method described in the first aspect.

[0024] Preferably, the thickness of the modified polyimide dielectric film material is 5~50μm.

[0025] A third aspect of this application provides a thin-film capacitor, wherein the metallized film comprises the modified polyimide dielectric film material described in the second aspect.

[0026] Preferably, the metal electrode covering the surface of the modified polyimide dielectric film material in the metallized film is selected from at least one of aluminum electrode, zinc electrode, and silver electrode.

[0027] The fourth aspect of this application provides the application of the modified polyimide dielectric film material described in the second aspect in the preparation of film capacitors.

[0028] Compared with the prior art, the method for preparing the modified polyimide dielectric film material provided in this application has at least the following beneficial effects:

[0029] 1. In the preparation method of the modified polyimide dielectric film material provided in this application, the thioether structure in 4,4'-thiodiphthalic anhydride is oxidized by using an oxidant to obtain a thiooxy bond (S=O), resulting in a polarized modified dianhydride. The polyimide dielectric film prepared by using this as a monomer and diamine has higher breakdown field strength / dielectric constant and other properties at high temperature, thus improving the performance of the polyimide dielectric film material.

[0030] 2. In the preparation method of the modified polyimide dielectric film material provided in this application, in addition to using sulfur-oxygen bonds (S=O) to obtain polarized modified dianhydride, titanium oxide nanoparticles are also used for modification, which further improves the breakdown field strength / dielectric constant and other properties of the polyimide dielectric film material at high temperature.

[0031] 3. The modified polyimide dielectric film material provided in this application uses polyimide as the substrate and adds polarized modified dianhydride and titanium dioxide nanoparticles for modification. The thin film capacitor assembled after the dielectric film material is made into a metallized film is suitable as an energy storage device in high-temperature application scenarios. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart of the preparation method of the modified polyimide dielectric film material provided in Example 1 of this application;

[0034] Figure 2 This is a schematic diagram illustrating the preparation of polarized modified dianhydride monomers in the method for preparing the modified polyimide dielectric film material provided in Example 1 of this application.

[0035] Figure 3 The diagram shows the breakdown field strength test results of dielectric film samples made of polyimide dielectric film materials provided in Examples 1-3 of this application.

[0036] Figure 4The graph shows the dielectric constant test results of dielectric film samples made from the polyimide dielectric film materials provided in Examples 1-3 of this application.

[0037] Figure 5 The graph shows the discharge energy test results of dielectric film samples made from polyimide dielectric film materials provided in Examples 1-3 of this application. Detailed Implementation

[0038] This application provides a modified polyimide dielectric film material, its preparation method, and its application, which addresses the technical problem of low performance of polyimide dielectric film materials in the prior art.

[0039] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Given the current lack of effective methods to improve the polarization performance of polyimide (PI) dielectric film materials, this application improves the performance of polyimide (PI) dielectric film materials through a dual modification approach of molecular structure optimization and high dielectric constant nanoparticle composite modification. The preparation method of the modified polyimide dielectric film material includes: selecting a specific dianhydride 4,4'-thiophthalic anhydride with a thioether structure, first oxidizing the thioether structure in the 4,4'-thiophthalic anhydride with an oxidant to obtain a polarized modified dianhydride monomer; then mixing the polarized modified dianhydride monomer, diamine monomer, high dielectric constant nanoparticles and organic solvent and performing polycondensation to obtain a polyamic acid solution doped with titanium oxide nanoparticles; next, coating the polyamic acid solution onto a substrate by means of casting or other methods, and then evaporating the organic solvent to obtain a modified polyamic acid film; finally, crosslinking and curing the modified polyamic acid film to obtain the modified polyimide dielectric film material.

[0041] In the preparation method provided in this application, a specific dianhydride, 4,4'-thiophthalic anhydride, with a thioether structure is selected. The sulfur in the thioether structure (RSR) is in an oxidation state of 0, making it chemically reactive and easily oxidized by oxidizing agents. This application uses oxidizing agents such as m-chloroperoxybenzoic acid to selectively oxidize it, causing the thioether structure (RSR) to be oxidized to a more polar sulfur-oxygen bond (S=O), obtaining a polarized modified dianhydride monomer. Subsequently, the polarized modified dianhydride monomer, diamine monomer, and high dielectric constant nanoparticles are prepared into a polyamic acid solution, which is then crosslinked and cured to form a modified polyimide dielectric film material. Because the modified polyimide provided in this application… The use of polarized modified dianhydride as a monomer in imide dielectric thin film materials can improve the dielectric constant and breakdown field strength, as well as increase the energy storage density. Furthermore, doping the dielectric thin film with high-dielectric-constant nanoparticles such as titanium oxide nanoparticles can further enhance these properties. Additionally, the use of polyimide as the base material results in a wider operating temperature range, making it a high-performance dielectric thin film material suitable for high-temperature applications. This addresses the technical problem of low performance in existing polyimide dielectric thin film materials.

[0042] In the method for preparing dielectric thin film materials provided in this application, during the preparation of polarized modified dianhydride monomers, the molar ratio of 4,4'-thiophthalic anhydride and oxidant is controlled to be 1:1~1.2, for example, 1:1.05, 1:1.1, etc.; the molar amount of oxidant is slightly greater than that of 4,4'-thiophthalic anhydride, which can ensure that the thioether structure (RSR) in 4,4'-thiophthalic anhydride is completely oxidized to thiooxy bonds (S=O).

[0043] In the method for preparing dielectric thin film materials provided in this application, the oxidation reaction temperature is controlled to be room temperature, for example, 20~30℃, during the preparation of polarized modified dianhydride monomer; and the crosslinking and curing temperature of polyamic acid film is controlled to increase sequentially, for example, crosslinking at 120~180℃, 180~220℃, and 230~270℃ sequentially.

[0044] In the dielectric thin film material preparation method provided in this application, the doped nanoparticles with high dielectric constants can be selected from nanoparticles with high dielectric constants such as titanium oxide nanoparticles, zirconium oxide nanoparticles, niobium oxide nanoparticles, lanthanum oxide nanoparticles, and hafnium oxide nanoparticles, with an average particle size of 20~100nm, such as 30nm, 50nm, and 80nm; titanium oxide nanoparticles are further preferred, as the dielectric constant of titanium oxide nanoparticles can reach 110. When doped in small amounts, such as 0.5%, the dielectric thin film material can be significantly improved.

[0045] Accordingly, this application also provides the application of the modified polyimide dielectric film material prepared by the above preparation method, specifically in film capacitors; for example, the surface of the modified polyimide dielectric film material can be coated with a thin layer of aluminum / zinc / silver electrode by vacuum evaporation process to form a metallized film.

[0046] The preparation method of a modified polyimide dielectric film material provided in this application will be specifically described below with reference to embodiments and experimental examples.

[0047] Example 1

[0048] This embodiment provides a method for preparing a modified polyimide dielectric thin film material, the process flow diagram of which is shown below. Figure 1 As shown, the preparation method includes the steps of preparing a polarized modified dianhydride monomer, preparing a polyamic acid, preparing a polyamic acid film, and preparing a polyimide film.

[0049] The reaction diagram for the step of preparing the polarized modified dianhydride monomer is shown below. Figure 2 As shown, the oxidation reaction involved mixing and dissolving 0.1 mol of 4,4'-thiophthalic anhydride (CAS No.: 25884-43-9), 0.11 mol of m-chloroperoxybenzoic acid, and 300 ml of chloroform, and then carrying out the oxidation reaction at room temperature for 1 h to completely oxidize the thioether structure (RSR) to a thiooxy bond (S=O). Subsequently, the oxidation reaction was purified by silica gel column chromatography, retaining the more polar eluent, rotary evaporating, and drying in a vacuum oven at 80 °C for 12 h to obtain a polarized modified dianhydride monomer solid, named 4,4'-thiophthalic anhydride sulfoxide.

[0050] The steps for preparing polyamic acid include: first, drying m-phenylenediamine and titanium dioxide nanoparticles in a vacuum oven at 80℃ for 12 h; then, weighing 0.05 moles of polarized modified dianhydride monomer and 0.05 moles of m-phenylenediamine according to a molar ratio of 1:1; then weighing 0.11 g of titanium dioxide nanoparticles according to 0.5% of the sum of the mass of polarized modified dianhydride monomer and diamine monomer; then, dissolving the weighed m-phenylenediamine in 500 mL of anhydrous N-methylpyrrolidone (NMP) at room temperature for 30 min; then adding the weighed titanium dioxide nanoparticles to N-methylpyrrolidone (NMP) and ultrasonically dispersing for 2 h to form a uniform suspension; then adding the weighed polarized modified dianhydride monomer to N-methylpyrrolidone (NMP) and stirring vigorously with a magnetic stirrer at room temperature for 10 h to ensure complete monomer condensation reaction, thus obtaining a polyamic acid solution doped with titanium dioxide nanoparticles.

[0051] The steps for preparing polyamic acid films include: preparing a polyamic acid solution doped with titanium dioxide nanoparticles.

[0052] The polyamic acid film was cast onto a pre-cleaned glass slide, and a wet film of polyamic acid doped with titanium dioxide nanoparticles was coated onto the substrate. Then, it was dried in a vacuum oven at 60°C for 10 hours to evaporate the N-methylpyrrolidone (NMP) organic solvent, thus obtaining a modified polyamic acid film.

[0053] The steps for preparing the polyimide film include: cross-linking and curing the modified polyamic acid film sequentially at 150℃ for 1 h, 200℃ for 1 h, and 250℃ for 1 h to obtain the modified polyimide dielectric film material; then, the modified polyimide dielectric film material on the glass slide is placed in deionized water for peeling, and the film material is placed at 60℃ for 12 h to remove all moisture and residual solvent, resulting in a modified polyimide dielectric film material with a thickness of approximately 10 μm for later use.

[0054] Example 2

[0055] This embodiment provides a method for preparing a modified polyimide dielectric film material. As the first comparative example of Example 1, the preparation method includes the steps of preparing a polarized modified dianhydride monomer, preparing polyamic acid, preparing a polyamic acid film, and preparing a polyimide film. The difference between the preparation method and Example 1 is that titanium oxide nanoparticles are not added.

[0056] The steps for preparing the polarized modified dianhydride monomer include: mixing and dissolving 0.1 mol of 4,4'-thiophthalic anhydride (CAS No.: 25884-43-9), 0.11 mol of m-chloroperoxybenzoic acid, and 300 ml of chloroform, and then performing an oxidation reaction at room temperature for 1 h to completely oxidize the thioether structure (RSR) to a thiooxy bond (S=O); subsequently purifying the oxidation reaction by using silica gel column chromatography, retaining the more polar eluent, rotary evaporating, and drying in a vacuum oven at 80 °C for 12 h to obtain the polarized modified dianhydride monomer solid, named 4,4'-thiophthalic anhydride sulfoxide.

[0057] The steps for preparing polyamic acid include: first, drying m-phenylenediamine in a vacuum oven at 80°C for 12 h; then, weighing 0.05 moles of polarized modified dianhydride monomer and 0.05 moles of m-phenylenediamine according to a molar ratio of 1:1; then, dissolving the weighed m-phenylenediamine in 500 mL of anhydrous N-methylpyrrolidone (NMP) at room temperature for 30 min; then, adding the weighed polarized modified dianhydride monomer to N-methylpyrrolidone (NMP) and stirring vigorously with a magnetic stirrer at room temperature for 10 h to ensure complete monomer polycondensation reaction, thereby obtaining a polarized modified polyamic acid solution.

[0058] The steps for preparing polyamic acid films include: casting a polarization-modified polyamic acid solution onto a pre-cast laitance.

[0059] A polarization-modified polyamic acid wet film was coated onto a cleaned glass slide and then dried in a vacuum oven at 60°C for 10 hours to evaporate the N-methylpyrrolidone (NMP) organic solvent, resulting in a polarization-modified polyamic acid film. The steps for preparing the polyimide film included: sequentially crosslinking and curing the polarization-modified polyamic acid film at 150°C for 1 hour, 200°C for 1 hour, and 250°C for 1 hour to obtain a modified polyimide dielectric film material; subsequently, the modified polyimide dielectric film material on the glass slide was peeled off in deionized water, and the film material was placed at 60°C for 12 hours to remove all moisture and residual solvent, resulting in a modified polyimide dielectric film material with a thickness of approximately 10 μm for later use.

[0060] Example 3

[0061] This embodiment provides a method for preparing a polyimide dielectric film material. As a second comparative example of Example 1, the preparation method includes the steps of preparing polyamic acid, preparing a polyamic acid film, and preparing a polyimide film. The difference between the preparation method and Example 1 is that titanium oxide nanoparticles are not added.

[0062] The steps for preparing polyamic acid include: first, drying m-phenylenediamine and 4,4'-thiophthalic anhydride (CAS No.: 25884-43-9) in a vacuum oven at 80℃ for 12 h; then, weighing 0.05 moles of 4,4'-thiophthalic anhydride and 0.05 moles of m-phenylenediamine in a molar ratio of 1:1; then, dissolving the weighed m-phenylenediamine in 500 mL of anhydrous N-methylpyrrolidone (NMP) at room temperature for 30 min; then, adding the weighed 4,4'-thiophthalic anhydride to N-methylpyrrolidone (NMP) and stirring vigorously with a magnetic stirrer at room temperature for 10 h to ensure complete monomer polycondensation reaction, thus obtaining a polyamic acid solution.

[0063] The steps for preparing polyamic acid films include: casting a polyamic acid solution onto a pre-cleaned glass substrate.

[0064] A polyamic acid wet film is coated onto a glass slide and then dried in a vacuum oven at 60°C for 10 hours to evaporate the N-methylpyrrolidone (NMP) organic solvent, resulting in a polyamic acid film. The steps for preparing the polyimide film include: sequentially crosslinking and curing the polyamic acid film at 150°C for 1 hour, 200°C for 1 hour, and 250°C for 1 hour to obtain a polyimide dielectric film material; subsequently, the polyimide dielectric film material on the glass slide is peeled off by immersing it in deionized water, and the film material is placed at 60°C for 12 hours to remove all moisture and residual solvent, resulting in a polyimide dielectric film material with a thickness of approximately 10 μm for later use.

[0065] Experimental Example 1

[0066] In this experimental example, the polyimide dielectric film materials provided in Examples 1-3 were respectively made into dielectric film samples for performance testing. The performance tests included breakdown field strength testing, dielectric constant testing, and discharge energy density testing.

[0067] The breakdown field strength test process includes: placing the three dielectric film samples made of the polyimide dielectric film materials provided in Examples 1-3 into a ball-to-ball electrode gap at 150°C for breakdown field strength testing. Each of the three dielectric film samples underwent 20 breakdown cycles to obtain the breakdown voltage data. The breakdown field strength of the two films was calculated using the formula, and the Weibull distribution diagrams of the three films were further plotted. The test results are shown below. Figure 3 As shown.

[0068] The dielectric constant testing process included: using a Q150T electrode evaporation apparatus to spray 10mm diameter silver electrodes onto the polyimide dielectric film materials provided in Examples 1-3, and then placing the three dielectric film samples at 150°C into a Concept 80 broadband dielectric impedance spectrometer for dielectric constant testing. The test results are as follows: Figure 4 As shown.

[0069] The discharge energy density test process included: using a Q150T electrode evaporation apparatus to spray a 3 mm diameter silver electrode onto the polyimide dielectric film material provided in Examples 1-3; and conducting the test under test conditions of 150℃ and 400 kV / mm in a dielectric charge-discharge test system. The test results are as follows: Figure 5 As shown.

[0070] from Figure 3-4It can be seen that the unmodified ordinary polyimide dielectric film sample provided in Example 3 has a low breakdown field strength of 296.0 kV / mm, while the modified polyimide dielectric film sample prepared by using polarized modified dianhydride as a monomer and diamine monomer in Example 2 has a significantly improved breakdown field strength of 352.5 kV / mm. Furthermore, the polyimide dielectric film sample provided in Example 1, after incorporating titanium dioxide nanoparticles, yields a modified polyimide... The breakdown field strength of the dielectric film sample was further increased to 391.2 kV / mm; this is because the polarized modified dianhydride used in Examples 1-2 was obtained by oxidizing the thioether structure (RSR) in 4,4'-thiophthalic anhydride to a thiooxy bond (S=O), which has stronger polarity. Simultaneously, the dielectric constant of the titanium dioxide nanoparticles used in Example 1 is around 100. The combined addition of these two factors significantly improved the breakdown field strength of the modified polyimide dielectric film. Figure 4 The dielectric constant results also show that adding polarized modified dianhydride and titanium dioxide nanoparticles can improve the dielectric constant of the modified polyimide dielectric film.

[0071] from Figure 5 It can be seen that the modified polyimide dielectric film provided in Example 1 has a higher discharge energy density. This is because the modified polyimide dielectric film provided in Example 1 uses polarized modified dianhydride / titanium dioxide nanoparticles, which improves its dielectric constant, breakdown field strength and other properties at high temperature (150°C). The energy storage and charge / discharge performance at high temperature is improved. The film capacitor assembled after the dielectric film is made into a metallized film is suitable as an energy storage device at high temperature.

[0072] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a modified polyimide dielectric thin film material, characterized in that, Includes the following steps: 4,4'-thiophthalic anhydride was dissolved in an organic solvent, and an oxidizing agent was added to oxidize the thioether structure in the 4,4'-thiophthalic anhydride. After purification, polarized modified dianhydride monomer was obtained. Polarized modified dianhydride monomer, diamine monomer, high dielectric constant nanoparticles and organic solvent were mixed and polycondensed to obtain a polyamic acid solution doped with titanium oxide nanoparticles. A modified polyamic acid film is obtained by coating a substrate with a polyamic acid wet film doped with titanium oxide nanoparticles and then evaporating the organic solvent. The modified polyamic acid film was cross-linked and cured to obtain a modified polyimide dielectric film material.

2. The method for preparing a modified polyimide dielectric thin film material according to claim 1, characterized in that, The oxidant includes at least one of m-chloroperoxybenzoic acid, sodium hypochlorite, and hydrogen peroxide.

3. The method for preparing a modified polyimide dielectric thin film material according to claim 1, characterized in that, The high dielectric constant nanoparticles include at least one of titanium oxide nanoparticles, zirconium oxide nanoparticles, niobium oxide nanoparticles, lanthanum oxide nanoparticles, and hafnium oxide nanoparticles.

4. The method for preparing a modified polyimide dielectric thin film material according to claim 1, characterized in that, The oxidation reaction was carried out at room temperature for 0.5 to 2 hours.

5. The method for preparing a modified polyimide dielectric thin film material according to claim 1, characterized in that, The cross-linking curing process includes: cross-linking and curing at 120~180℃ for 0.5~2h, cross-linking and curing at 180~220℃ for 0.5~2h, and cross-linking and curing at 230~270℃ for 0.5~2h in sequence.

6. The method for preparing a modified polyimide dielectric thin film material according to claim 1, characterized in that, The molar ratio of the 4,4'-thiophthalic anhydride to the oxidant is 1:1 to 1.

2.

7. The method for preparing a modified polyimide dielectric thin film material according to claim 1, characterized in that, The molar ratio of the polarized modified dianhydride monomer to the diamine monomer is 1:1, and the amount of the high dielectric constant nanoparticles added is 0.2 to 1% of the sum of the masses of the polarized modified dianhydride monomer and the diamine monomer.

8. A modified polyimide dielectric film material, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. A thin-film capacitor, characterized in that, Its metallized film includes the modified polyimide dielectric film material as described in claim 8.

10. The application of the modified polyimide dielectric film material according to claim 8 in the preparation of film capacitors.

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