Bismaleimide-based thermosetting dielectric film and preparation method therefor, and capacitor

Abstract

A bismaleimide-based thermosetting dielectric film and a preparation method therefor, and a capacitor. The preparation method comprises: dispersing a bismaleimide resin, a diamine chain extender, a catalyst and a nanofiller into an N,N-dimethylformamide solution, to obtain a bismaleimide system composition slurry, the catalyst being an anionic catalyst or a free radical initiator; coating the bismaleimide system composition slurry on a substrate, and sequentially performing film forming, curing, film stripping and drying treatment, to obtain the bismaleimide-based thermosetting dielectric film. The prepared bismaleimide-based thermosetting dielectric film has a cross-linked network structure and can withstand a high temperature of 250°C, has strong solvent resistance, and exhibits excellent energy storage performance at high temperatures of 150°C and above and in electric fields of 400MV / m and higher, such as high breakdown field strength (Eb≥600MV / m), high charge and discharge efficiency (η≥90%) and high discharge energy density (Ue≥5J / cm 3).

Description

Bismaleimide-based thermosetting dielectric film, preparation method thereof, and capacitor Technical Field

[0001] The present invention relates to the technical field of high-temperature electrostatic energy storage, and in particular to a bismaleimide-based thermosetting dielectric film, a preparation method thereof, and a capacitor. Background Art

[0002] At present, the high-temperature polymer dielectrics used in film capacitors are mainly thermoplastic engineering plastics with a high glass transition temperature (Tg), such as polyetherimide (PEI), polyphenylene sulfide (PPS), polyester (PET), polyetheretherketone (PEEK), etc. Although these engineering plastics have a high Tg and meet the mechanical temperature resistance requirements, their high-temperature dielectric energy storage performance is still unsatisfactory. For example, the conductivity loss will still increase significantly at a high temperature of 150°C, resulting in a significant decrease in breakdown field strength, energy storage density, and charge and discharge efficiency. Moreover, the polarity of these materials is usually low, and their polarization ability is limited under the electric field, resulting in a low dielectric constant.

[0003] Therefore, the existing technology needs to be further improved and enhanced.

[0004] Summary of the Invention

[0005] In view of the shortcomings of the above-mentioned prior art, the present invention aims to provide a bismaleimide-based thermosetting dielectric film, a preparation method thereof, and a capacitor. The present invention uses a free radical initiator or an anionic polymerization initiator to initiate a polymerization reaction between a bismaleimide resin and a diamine chain extender, copolymerizing and extending the chain to form a cross-linked network structure film. The prepared film exhibits excellent energy storage properties, including high dielectric constant, low dielectric loss, high thermal stability, high breakdown field strength, high charge-discharge efficiency, and high energy storage density.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In the first aspect, a bismaleimide resin, a diamine chain extender, a catalyst, and a nanofiller are dispersed in a solvent such as N,N-dimethylformamide, N-methylpyrrolidone, butanone, or cyclohexanone to obtain a bismaleimide system composition slurry; the catalyst is an anionic catalyst or a free radical initiator;

[0008] The bismaleimide system composition slurry is coated on a substrate, and is sequentially subjected to film formation, curing, film stripping, and drying processes to obtain a bismaleimide-based thermosetting dielectric film.

[0009] As a preferred technical solution, the method for preparing the bismaleimide-based thermosetting dielectric film, wherein the bismaleimide (BMI) has the general formula shown in Formula I:

[0010] Wherein R1 can be selected from but not limited to one of the following structures: -(CH2)6-, -(CH2) 10 -.

[0011] As a preferred technical solution, the preparation method of the bismaleimide-based thermosetting dielectric film, wherein the diamine chain extender is selected from at least one of diaminodiphenylmethane (DDM), diaminodiphenyl sulfone (DDS), 4,4'-diaminodiphenyl ether (ODA), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone (MBAPS), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) and 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA); wherein the molecular structure of diaminodiphenylmethane is The molecular structure of diaminodiphenyl sulfone is The molecular structure of 4,4'-diaminodiphenyl ether is The molecular structure of bis[4-(4-aminophenoxy)phenyl]sulfone is The molecular structure of 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone is The molecular structure of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane is The molecular structure of 9,9-bis(3-fluoro-4-aminophenyl)fluorene is

[0012] As a preferred technical solution, the method for preparing the bismaleimide-based thermosetting dielectric film, wherein the anion catalyst is selected from one including but not limited to 2-ethyl-4-methylimidazole (2E4MZ), 2-methylimidazole (2MZ) and 2-phenylimidazole (2-PZ); the free radical initiator is a high-temperature resistant initiator with a decomposition temperature higher than 170°C with a half-life of 1 minute, and is selected from one including but not limited to di-tert-butyl peroxyisopropylbenzene (BIPB), di-tert-butyl peroxide (DTPB) and diisopropylbenzene peroxide (DCP).

[0013] As a preferred technical solution, in the method for preparing the bismaleimide-based thermosetting dielectric film, the added amount of the catalyst is 0.05wt%-2wt%, preferably 0.1wt%-1wt%; the added amount of the nanofiller is 0.1wt%-3wt%, preferably 0.5wt%-1.5wt%.

[0014] As a preferred technical solution, in the method for preparing the bismaleimide-based thermosetting dielectric film, the nanofiller is selected from at least one of nano-aluminum oxide, nano-silicon dioxide, nano-boron nitride, nano-titanium dioxide, nano-magnesium oxide and nano-hafnium oxide.

[0015] The particle sizes of nano-aluminum oxide, nano-silicon dioxide, nano-titanium dioxide, nano-magnesium oxide, and nano-hafnium oxide are 1-100 nm, preferably 5-20 nm, and the particle size of nano-boron nitride is 100-200 μm, preferably 1 μm. The nanofillers primarily provide deep traps, capturing carriers in the cured film under high-temperature, high-field excitation, thereby reducing leakage current, improving breakdown field strength, and improving charge and discharge efficiency.

[0016] As a preferred technical solution, in the method for preparing the bismaleimide-based thermosetting dielectric film, the molar ratio of the bismaleimide to the diamine is 10:1-1:1, preferably 6:1-2:1.

[0017] As a preferred technical solution, the method for preparing the bismaleimide-based thermosetting dielectric film, wherein the bismaleimide system composition slurry is coated on a substrate, and film formation, curing, film stripping, and drying are sequentially performed to obtain the bismaleimide-based thermosetting dielectric film, specifically comprising:

[0018] Applying the bismaleimide system composition slurry onto a substrate and baking at 60-80° C.;

[0019] The baked substrate is placed in an oxygen-free inert atmosphere, such as a vacuum oven or a nitrogen oven, and cured in stages within a temperature range of 100-250°C to obtain a substrate with a cured film. Staged curing refers to the process of first raising the temperature to a certain temperature within a temperature range, baking at that temperature for a period of time, then continuing to raise the temperature to another temperature, baking at that temperature for a period of time, then continuing to raise the temperature to a certain value, baking for a period of time, and then raising the temperature again until the process requirements are met. For example, if an anionic catalyst such as 2-ethyl-4-methylimidazole (2E4MZ) is used, the curing reaction process is preferably baking at 150°C for 2 hours, then heating to 180°C for 2 hours, then heating to 200°C for 3 hours, and then heating again to 230°C for 4 hours. If a free radical initiator such as di-tert-butylperoxyisopropylbenzene (BIPB) is used, the curing process is preferably baking at 150°C for 3 hours, then heating to 190°C for 3 hours, and then heating to 220°C for 4 hours.

[0020] The substrate with the cured film is placed in deionized water for film removal, and the removed film is placed in a vacuum oven for drying to obtain a bismaleimide-based thermosetting dielectric film.

[0021] In a second aspect, a bismaleimide-based thermosetting dielectric film is provided, wherein the bismaleimide-based thermosetting dielectric film is prepared using the above-mentioned preparation method.

[0022] In a third aspect, a capacitor is provided, wherein the capacitor is a thin film capacitor, comprising the bismaleimide-based thermosetting dielectric film described above.

[0023] Beneficial effects: Compared with the prior art, the bismaleimide-based thermosetting dielectric film prepared by the present invention has a cross-linked network structure, can withstand high temperatures of 250°C; is insoluble and infusible, and has strong solvent resistance; in particular, it has excellent high-temperature dielectric energy storage performance, and exhibits excellent energy storage performance at high temperatures of 150°C and above 400MV / m and strong electric fields, such as high breakdown field strength (Eb≥600MV / m), high charge and discharge efficiency (η≥90%), and high discharge energy density (Ue≥5J / cm 3 ). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Example 1 of the present invention.

[0025] FIG2 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Example 2 of the present invention.

[0026] FIG3 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Example 3 of the present invention.

[0027] FIG4 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Example 4 of the present invention.

[0028] FIG5 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Example 5 of the present invention.

[0029] FIG6 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Example 6 of the present invention.

[0030] FIG7 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Comparative Example 1 of the present invention.

[0031] FIG8 is a diagram showing the energy storage density of the bismaleimide-based thermosetting dielectric film obtained in Comparative Example 2 of the present invention.

[0032] FIG9 shows the variation of the dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film obtained in Example 1 of the present invention with frequency.

[0033] FIG10 shows the variation of the dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film obtained in Example 2 of the present invention with frequency.

[0034] FIG11 shows the variation of the dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film obtained in Example 3 of the present invention with frequency.

[0035] FIG12 shows the variation of the dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film obtained in Example 4 of the present invention with frequency. DETAILED DESCRIPTION

[0036] The present invention provides a bismaleimide-based thermosetting dielectric film, a method for preparing the same, and a capacitor. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0037] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the description of the present invention refers to the presence of the stated features, integers, and steps, but does not preclude the presence or addition of one or more other features.

[0038] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0039] The present invention provides a method for preparing a bismaleimide-based thermosetting dielectric film, comprising the following steps:

[0040] S10, dissolving bismaleimide, a diamine chain extender, 2-ethyl-4-methylimidazole (2E4MZ), or a catalyst such as bis-tert-butylperoxyisopropylbenzene (BIPB) in a certain proportion in an N,N-dimethylformamide (DMF) solution, and heating under magnetic stirring to fully dissolve the solution to obtain solution A. Add a certain amount of nanofiller to the N,N-dimethylformamide solvent and ultrasonically disperse the solution to obtain solution B. Mix A and B and continue to stir and disperse to obtain a bismaleimide system composition slurry;

[0041] S20, after uniformly coating the slurry on the glass substrate, volatilize the solvent in an oven at 70° C.;

[0042] S30, placing the glass substrate after the solvent has evaporated into a vacuum oven, and subjecting it to a curing reaction at multiple temperatures between 100° C. and 250° C. to obtain a cured film;

[0043] S40, placing the glass substrate with the cured film in deionized water for film removal, placing the removed film in a vacuum oven for high-temperature drying, and obtaining a bismaleimide-based thermosetting dielectric film with a dense cross-linked network structure.

[0044] The bismaleimide-based thermosetting dielectric film and the preparation method thereof provided by the present invention are further explained below in conjunction with specific preparation examples.

[0045] Example 1:

[0046] The raw materials involved in this embodiment include N,N′-(4,4′-methylenediphenyl)bismaleimide (BDM), 4,4″-diaminodiphenyl ether (ODA), and 2-ethyl-4-methylimidazole (2E4MZ).

[0047] The preparation steps are as follows:

[0048] Mix N,N′-(4,4′-methylenediphenyl)bismaleimide (BDM) and ODA in a 5:1 molar ratio, add 1 wt% of 2-ethyl-4-methylimidazole (2E4MZ) anionic catalyst, and prepare a 2 wt% solution. For example, weigh 0.1799 g of bismaleimide (BMI), 0.0201 g of 4,4″-diaminodiphenyl ether (ODA), and 0.002 g of 2-ethyl-4-methylimidazole (2E4MZ), and add 10 ml of N,N-dimethylformamide (DMF) to prepare the solution.

[0049] The above solution was heated to 45° C. under magnetic stirring and dissolved and dispersed for 8 hours to allow the material to be fully and evenly dissolved in the solvent.

[0050] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0051] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 160°C for two hours, 180°C for two hours, 200°C for two hours, and 220°C for two hours. After natural cooling, a cured film is obtained.

[0052] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0053] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0054] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this embodiment is shown in FIG1 . At 150° C., the film has high energy storage density and efficiency. When the electric field strength is 300 MV / m, the charge and discharge efficiency is still 92%, and the discharge energy density is 1.19 J / cm 3 The dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film prepared in this embodiment vary with frequency as shown in FIG5 . At a frequency of 1 MHz, the dielectric constant is 3.75 and the dielectric loss is 0.018. This composition has a high dielectric constant and low dielectric loss.

[0055] Example 2:

[0056] The raw materials involved in this embodiment include BDM, 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone (MBAPS), and 2E4MZ.

[0057] The preparation steps are as follows:

[0058] According to a molar ratio of BDM to MBAPS of 7:1, a 2-ethyl-4-methylimidazole (2E4MZ) anion catalyst content of 1 wt% and a solution mass concentration of 2 wt%, 0.1706 g of bismaleimide (BMI), 0.0294 g of 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone (MBAPS), and 0.002 g of 2-ethyl-4-methylimidazole (2E4MZ) were weighed and 10 ml of N,N-dimethylformamide (DMF) was added to prepare a solution.

[0059] The glass bottle containing the membrane-forming solution was placed on a magnetic stirring table heated at 45° C. and stirred for 8 hours to allow the material to be fully and evenly dissolved in the solvent.

[0060] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0061] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 160°C for two hours, 180°C for two hours, 200°C for two hours, and 220°C for two hours. After natural cooling, a cured film is obtained.

[0062] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0063] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0064] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this embodiment is shown in FIG2 . At 150° C., the film has high energy storage density and efficiency. When the electric field strength is 400 MV / m, the charge and discharge efficiency is still 88%, and the discharge energy density is 2.45 J / cm 3 The dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film prepared in this embodiment vary with frequency as shown in FIG6 . At a frequency of 1 MHz, the dielectric constant is 3.26 and the dielectric loss is 0.014. This composition has a high dielectric constant and low dielectric loss.

[0065] Example 3:

[0066] The raw materials involved in this embodiment include BDM, MBAPS, and di-tert-butylperoxyisopropylbenzene (BIPB).

[0067] According to a 2:1 molar ratio of BDM to MBAPS, a 1 wt% bis-tert-butylperoxyisopropylbenzene (BIPB) free radical catalyst content and a 2 wt% solution concentration, 0.1247 g of bismaleimide (BDM), 0.0753 g of 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone (MBAPS), and 0.002 g of bis-tert-butylperoxyisopropylbenzene (BIPB) were weighed and 10 ml of N,N-dimethylformamide (DMF) was added to prepare a solution.

[0068] The glass bottle containing the membrane-forming solution was placed on a magnetic stirring table heated at 45° C. and stirred for 8 hours to allow the material to be fully and evenly dissolved in the solvent.

[0069] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0070] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 150°C for three hours, 190°C for three hours, and 220°C for four hours. After natural cooling, a cured film is obtained.

[0071] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0072] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0073] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this embodiment is shown in FIG3 . At 150° C., the film has high energy storage density and efficiency. When the electric field strength is 400 MV / m, the charge and discharge efficiency is still 90%, and the corresponding discharge energy density is 3.14 J / cm 3 The dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film prepared in this embodiment vary with frequency as shown in FIG7 . At a frequency of 1 MHz, the dielectric constant is 3.46 and the dielectric loss is 0.018. This composition has a high dielectric constant and low dielectric loss.

[0074] Example 4:

[0075] The raw materials involved in this embodiment include BDM, ODA, and BIPB.

[0076] According to the molar ratio of BDM to ODA of 4:1, the free radical catalyst content of di-tert-butylperoxyisopropylbenzene (BIPB) of 0.1wt% and the solution concentration of 2wt%, 0.1755g of bismaleimide (BDM), 0.0245g of 4,4"-diaminodiphenyl ether (ODA), and 0.0002g of di-tert-butylperoxyisopropylbenzene (BIPB) were weighed and 10ml of N,N-dimethylformamide (DMF) was added to prepare a solution.

[0077] The glass bottle containing the membrane-forming solution was placed on a magnetic stirring table heated at 45° C. and stirred for 8 hours to allow the material to be fully and evenly dissolved in the solvent.

[0078] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0079] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 150°C for three hours, 190°C for three hours, and 220°C for four hours. After natural cooling, a cured film is obtained.

[0080] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0081] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0082] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this embodiment is shown in FIG4 . At 150° C., the film has high energy storage density and efficiency. When the electric field strength is 400 MV / m, the charge and discharge efficiency is still 88%, and the discharge energy density is 2.62 J / cm 3 The dielectric constant and dielectric loss of the bismaleimide-based thermosetting dielectric film prepared in this embodiment vary with frequency as shown in FIG8 . At a frequency of 1 MHz, the dielectric constant is 3.53 and the dielectric loss is 0.013. This composition has a high dielectric constant and low dielectric loss.

[0083] Example 5:

[0084] The raw materials involved in this embodiment include 2,2-bis[4-(4-maleimidephenoxy)phenyl]propane (BPABMI), ODA, and BIPB.

[0085] According to a 6:1 molar ratio of BPABMI to ODA, 1 wt% of a free radical catalyst, and a solution concentration of 2 wt%, 0.1890 g of 2,2-bis[4-(4-maleimidephenoxy)phenyl]propane (BPABMI), 0.0110 g of 4,4"-diaminodiphenyl ether (ODA), and 0.0020 g of di-tert-butylperoxyisopropylbenzene (BIPB) were weighed and 10 ml of N,N-dimethylformamide (DMF) was added to prepare a solution.

[0086] The glass bottle containing the membrane-forming solution was placed on a magnetic stirring table heated at 45° C. and stirred for 8 hours to allow the material to be fully and evenly dissolved in the solvent.

[0087] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0088] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 150°C for three hours, 190°C for three hours, and 220°C for four hours. After natural cooling, a cured film is obtained.

[0089] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0090] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0091] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this embodiment is shown in FIG5 . At 150° C., the film has high energy storage density and efficiency. When the electric field strength is 400 MV / m, the charge and discharge efficiency is still 90%, and the discharge energy density is 2.57 J / cm 3 When the electric field strength is 450MV / m, the charge and discharge efficiency is still 82%, and the discharge energy density is 3.10J / cm 3 .

[0092] Example 6:

[0093] The raw materials involved in this embodiment include BPABMI, MBAPS, BIPB, and Al2O3.

[0094] A solution of 0.1450 g of 2,2-bis[4-(4-maleimidephenoxy)phenyl]propane (BPABMI), 0.0550 g of 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone (MBAPS), and 0.0010 g of bis-tert-butylperoxyisopropylbenzene (BIPB) was added to 5 ml of N,N-dimethylformamide (DMF) at a 2:1 molar ratio of BPABMI to MBAPS, along with 0.5 wt% of a free radical catalyst. The mixture was stirred on a magnetic stirrer at 45°C for 8 hours to fully and evenly dissolve the materials in the solvent. 0.0010 g of 20 nm Al2O3 was then added to 5 ml of DMF and sonicated for 1 hour to fully disperse the Al2O3 nanofiller.

[0095] The two solutions were mixed and stirred on a magnetic stirring table at 45° C. for 2 hours.

[0096] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0097] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 150°C for three hours, 190°C for three hours, and 220°C for four hours. After natural cooling, a cured film is obtained.

[0098] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0099] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0100] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this embodiment is shown in FIG6 . At 150° C., the film has high energy storage density and energy storage efficiency. When the electric field strength is 400 MV / m, the charge and discharge efficiency is still 90%, and the discharge energy density is 3.09 J / cm 3 When the electric field strength is 500MV / m, the charge and discharge efficiency is still 80%, and the discharge energy density is 4.56J / cm 3 .

[0101] Comparative Example 1:

[0102] The raw materials involved in this comparative example include BDM and BIPB.

[0103] BDM self-polymerization

[0104] According to the free radical catalyst content of 0.5 wt%, 0.2 g of N,N′-(4,4′-methylenediphenyl)bismaleimide (BDM) and 0.0010 g of di-tert-butylperoxyisopropylbenzene (BIPB) were weighed and 10 ml of N,N-dimethylformamide (DMF) were added to prepare a solution.

[0105] The glass bottle containing the membrane-forming solution was placed on a magnetic stirring table heated at 45° C. and stirred for 8 hours to allow the material to be fully and evenly dissolved in the solvent.

[0106] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0107] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 180°C for two hours, 200°C for two hours, and 230°C for four hours. After natural cooling, a cured film is obtained.

[0108] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0109] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0110] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this comparative example is shown in FIG7 . At 150°C, it has low energy storage density and energy storage efficiency. When the electric field strength is 400 MV / m, the charge and discharge efficiency is only 21%, and the discharge energy density is 1.79 J / cm 3 .

[0111] Comparative Example 2:

[0112] BPABMI self-aggregation

[0113] According to the free radical catalyst content of 0.5 wt%, 0.2 g of 2,2-bis[4-(4-maleimidephenoxy)phenyl]propane (BPABMI) and 0.0010 g of bis-tert-butylperoxyisopropylbenzene (BIPB) were weighed and 10 ml of N,N-dimethylformamide (DMF) were added to prepare a solution.

[0114] The glass bottle containing the membrane-forming solution was placed on a magnetic stirring table heated at 45° C. and stirred for 8 hours to allow the material to be fully and evenly dissolved in the solvent.

[0115] Clean the glass slide to avoid dust contamination, then place the glass slide in a 70℃ oven to preheat for half an hour, then use a rubber-tipped dropper to draw about 5 ml of the film-making liquid and coat it on the glass slide, and bake it in a 70℃ oven for 10 hours to fully evaporate the solvent to obtain an uncured film.

[0116] After the solvent has evaporated, the glass sheet is placed in a vacuum oven and the temperature is adjusted to perform a multi-stage curing reaction. The temperature and time of each stage are: 180°C for two hours, 200°C for two hours, and 230°C for four hours. After natural cooling, a cured film is obtained.

[0117] Soak the glass slide with the cured film in deionized water. After a period of time, the film will fall off the glass slide by itself. Wrap the fallen film with aluminum foil.

[0118] The aluminum foil wrapped with the film was placed in a vacuum oven and dried at a high temperature of 120°C for 10 hours to obtain a bismaleimide-based thermosetting dielectric film with high electrostatic energy storage capacity.

[0119] The energy storage density of the bismaleimide-based thermosetting dielectric film prepared in this comparative example is shown in FIG8 . The energy storage density and energy storage efficiency at 150° C. are as follows: when the electric field strength is 300 MV / m, the charge and discharge efficiency is 93%, and the discharge energy density is 2.05 J / cm 3 , the breakdown field strength is 300MV.

[0120] The above comparison shows that the bismaleimide-based thermosetting dielectric film provided by the present invention can withstand high temperatures of 250°C; is insoluble and infusible, and has strong solvent resistance; in particular, it has excellent high-temperature dielectric energy storage performance, and exhibits excellent energy storage performance at high temperatures of 150°C and above 400MV / m and strong electric fields, such as high breakdown field strength (Eb ≥ 600MV / m), high charge and discharge efficiency (η ≥ 90%), and high discharge energy density (Ue ≥ 5J / cm 3 ).

[0121] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a bismaleimide-based thermosetting dielectric film, characterized in that: include: Dissolving and dispersing bismaleimide resin, diamine chain extender, catalyst and nanofiller in N,N-dimethylformamide solvent or N-methylpyrrolidone or butanone or cyclohexanone solvent to obtain bismaleimide system composition slurry; the catalyst is an anionic catalyst or a free radical initiator; The bismaleimide system composition slurry is coated on a substrate, and is sequentially subjected to film forming, curing, film stripping and drying processes to obtain a bismaleimide-based thermosetting dielectric film.

2. The method for preparing a bismaleimide-based thermosetting dielectric film according to claim 1, characterized in that: The bismaleimide has the general formula shown in Formula I: Wherein R1 is selected from one of the following structures: -(CH2)6-、-(CH2) 10 -。 3. The method for preparing a bismaleimide-based thermosetting dielectric film according to claim 1, characterized in that: The diamine chain extender is selected from at least one of diaminodiphenylmethane, diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and 9,9-bis(3-fluoro-4-aminophenyl)fluorene; wherein the molecular structure of diaminodiphenylmethane is The molecular structure of diaminodiphenyl sulfone is The molecular structure of 4,4'-diaminodiphenyl ether is The molecular structure of bis[4-(4-aminophenoxy)phenyl]sulfone is The molecular structure of 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone is The molecular structure of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane is The molecular structure of 9,9-bis(3-fluoro-4-aminophenyl)fluorene is 4. The method for preparing a bismaleimide-based thermosetting dielectric film according to claim 1, characterized in that: The anion catalyst is selected from one of 2-ethyl-4-methylimidazole, 2-methylimidazole and 2-phenylimidazole; the free radical initiator is selected from one of di-tert-butyl peroxyisopropylbenzene, di-tert-butyl peroxide and diisopropylbenzene peroxide.

5. The method for preparing a bismaleimide-based thermosetting dielectric film according to claim 1, characterized in that: The added amount of the catalyst is 0.05wt%-2wt%; the added amount of the nanofiller is 0.1wt%-3wt%.

6. The method for preparing a bismaleimide-based thermosetting dielectric film according to claim 1, characterized in that: The nano filler is selected from at least one of nano aluminum oxide, nano silicon dioxide, nano boron nitride, nano titanium dioxide, nano magnesium oxide and nano hafnium oxide.

7. The method for preparing a bismaleimide-based thermosetting dielectric film according to claim 1, characterized in that: The molar ratio of the bismaleimide to the diamine is 10:1-1:

1.

8. The method for preparing a bismaleimide-based thermosetting dielectric film according to claim 1, characterized in that: The method of coating the bismaleimide system composition slurry on a substrate, and sequentially subjecting the substrate to film formation, curing, film stripping, and drying to obtain a bismaleimide-based thermosetting dielectric film specifically includes: Applying the bismaleimide system composition slurry onto a substrate and baking at 60-80° C.; The baked substrate is placed in a vacuum oven or a nitrogen oven, and cured by increasing the temperature in stages within a temperature range of 100-250° C. to obtain a substrate with a cured film; The substrate with the cured film is placed in deionized water for film stripping, and the film stripped is placed in a vacuum oven for drying to obtain a bismaleimide-based thermosetting dielectric film.

9. A bismaleimide-based thermosetting dielectric film, characterized in that: The bismaleimide-based thermosetting dielectric film is prepared by the preparation method described in any one of claims 1-8.

10. A capacitor, characterized in that: The capacitor is a thin film capacitor, which comprises the bismaleimide-based thermosetting dielectric film according to claim 9.

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