Capacitor film for high-temperature application and preparation method thereof
By combining modified polyimide resin and modified montmorillonite nanosheets, the problem of high-temperature thin film materials being prone to failure at high temperatures was solved, thereby improving the high dielectric properties and high-temperature energy storage performance of capacitor films.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-03-27
AI Technical Summary
Existing high-temperature thin film materials are prone to softening, shrinkage, or dielectric degradation at high temperatures, leading to capacitor failure. Existing improvement methods lack stability and affect high-temperature energy storage performance.
Modified polyimide resin and modified montmorillonite nanosheets were used to improve dielectric properties and breakdown strength by introducing deep traps and Coulomb blocking effects of aluminum metal particles at the organic-inorganic interface.
It improves the dielectric properties and breakdown strength of capacitor films, enhances high-temperature energy storage performance, and improves the thermal stability and long-term reliability of the films.
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Figure CN121736493A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of capacitor film, in particular to a capacitor film for high temperature application and a preparation method thereof. BACKGROUND
[0002] Thin film capacitors play an important role in high temperature applications, used for filtering, energy storage and signal processing. With the development of high temperature electronic devices, such as engine control systems (operating temperature up to 150-200℃), traditional thin film materials such as polypropylene (PP) or polyester (PET) are prone to softening, shrinking or dielectric performance degradation at high temperatures, resulting in capacitor failure. Existing high temperature resistant materials mostly use polyimide (PI) or polytetrafluoroethylene (PTFE), but the thermal stability of pure polymer thin film is limited (glass transition temperature Tg<300℃), and cracks or increased loss are prone to occur in high temperature cycles. The existing technology tries to improve by adding organic stabilizers or composite layers, but the stabilizers have strong volatility and weak composite interface, resulting in performance degradation at long-term high temperature, affecting the high temperature energy storage performance of the capacitor. Based on this, a capacitor film for high temperature application and a preparation method thereof are proposed. SUMMARY
[0003] In view of the deficiencies of the prior art, the present application provides a capacitor film for high temperature application and a preparation method thereof, which improves the dielectric properties, breakdown strength and high temperature energy storage performance of the capacitor film under the combined action of the "Coulomb blocking effect" of aluminum metal particles, the excellent properties of montmorillonite nanosheets and the deep traps introduced at the organic-inorganic interface.
[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a capacitor film for high temperature application, comprising the following weight parts of raw materials: modified polyimide resin 70-90 parts, modified montmorillonite nanosheet 15-25 parts, crosslinking agent 1-3 parts, antioxidant 0.5-1.5 parts.
[0005] Preferably, the crosslinking agent is selected from bismaleimide; the antioxidant is selected from antioxidant 168.
[0006] Preferably, the preparation method of the modified polyimide resin is as follows: S11, 2,2-bis(trifluoromethyl)diaminobiphenyl and N,N-dimethylacetamide are put into a reactor and stirred to dissolve, then pyromellitic dianhydride is added and stirred to obtain a precursor solution; S12, the precursor solution is heated to imidize to obtain the modified polyimide resin.
[0007] Preferably, in step S11, the mass ratio of 2,2-bis(trifluoromethyl)diaminobiphenyl, pyromellitic dianhydride and N,N-dimethylacetamide is (4-5):(3-4):(45-60).
[0008] Preferably, in step S12, the heating treatment is gradient heating, which involves holding at 100°C for 40 min, at 150°C for 100 min, and at 200°C for 60 min in sequence, while controlling the heating rate to be 5°C / min.
[0009] Preferably, the modified montmorillonite nanosheets are prepared as follows: S21, montmorillonite nanosheets are dispersed in Tris-HCl aqueous solution, followed by the addition of dopamine hydrochloride, and stirring is continued for 10-12 hours. After centrifugation, rinsing and drying, pretreated montmorillonite nanosheets are obtained; S22, the pretreated montmorillonite nanosheets are ultrasonically dispersed in deionized water, followed by the addition of aluminum nitrate, and the reaction is stirred for 1-1.5 hours. After centrifugation, rinsing and drying, modified montmorillonite nanosheets are obtained.
[0010] Preferably, in step S21, the concentration of the Tris-HCl aqueous solution is 10 mM and the pH is 8.5; the ratio of montmorillonite nanosheets to Tris-HCl aqueous solution is 1:(15-20) g / mL; and the mass ratio of montmorillonite nanosheets to dopamine hydrochloride is (10-12):1.
[0011] Preferably, in step S22, the mass ratio of aluminum nitrate to pretreated montmorillonite nanosheets is 1:(30-35); the material-to-liquid ratio of pretreated montmorillonite nanosheets to deionized water is 1:(40-50) g / mL.
[0012] This invention also provides a method for preparing a capacitor film for high-temperature applications, comprising the following steps: (1) The modified polyimide resin, modified montmorillonite nanosheets, crosslinking agent and antioxidant are dispersed in N,N-dimethylacetamide and stirred at 100-120℃ for 2-3 hours to obtain a mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
[0013] Preferably, in step (1), the N,N-dimethylacetamide accounts for 70-75% of the mass of the mixed slurry.
[0014] This invention provides a capacitor film for high-temperature applications and its preparation method, which has the following advantages compared with the prior art: This invention introduces a small amount of trifluoromethyl groups into the molecular chain of polyimide. The trifluoromethyl groups have strong electronegativity and chemical stability, which can improve the breakdown and dielectric properties of capacitor films, as well as the heat resistance of the films.
[0015] This invention uses wide-bandgap, high-insulation montmorillonite nanosheets as the core, and reduces aluminum nitrate to metallic aluminum particles through a dopamine polymer interlayer and loads them on the nanosheets. The dielectric properties, breakdown strength and high-temperature energy storage performance of the capacitor film are improved by the combined effect of the "Coulomb blocking effect" of aluminum particles, the excellent properties of the montmorillonite nanosheets themselves and the deep traps introduced at the organic-inorganic interface. Attached Figure Description
[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is the FT-IR spectrum of the basic thin film sample in Example 1 of the present invention. Detailed Implementation
[0017] The following embodiments are provided to illustrate the implementation of this application in detail, so that the process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.
[0018] Example 1 The preparation method of modified polyimide resin is as follows: S11. 2,2-Di(trifluoromethyl)diaminobiphenyl and N,N-dimethylacetamide are placed in a reactor and stirred to dissolve. Then, pyromellitic dianhydride is added and stirring is continued to obtain a precursor solution. The mass ratio of 2,2-di(trifluoromethyl)diaminobiphenyl, pyromellitic dianhydride and N,N-dimethylacetamide is 5:4:60. S12. The precursor solution is subjected to heat treatment to imidize it. The heat treatment is a gradient heating, which is carried out at 100℃ for 40 min, 150℃ for 100 min, and 200℃ for 60 min in sequence. During the process, the heating rate is controlled at 5℃ / min to obtain the modified polyimide resin.
[0019] Example 2 The preparation method of modified polyimide resin is as follows: S11. 2,2-Di(trifluoromethyl)diaminobiphenyl and N,N-dimethylacetamide are placed in a reactor and stirred to dissolve. Then, pyromellitic dianhydride is added and stirring is continued to obtain a precursor solution. The mass ratio of 2,2-di(trifluoromethyl)diaminobiphenyl, pyromellitic dianhydride and N,N-dimethylacetamide is 4:3:45. S12. The precursor solution is subjected to heat treatment to imidize it. The heat treatment is a gradient heating, which is carried out at 100℃ for 40 min, 150℃ for 100 min, and 200℃ for 60 min in sequence. During the process, the heating rate is controlled at 5℃ / min to obtain the modified polyimide resin.
[0020] Example 3 The preparation method of modified montmorillonite nanosheets is as follows: S21. Montmorillonite nanosheets (50 nm) were dispersed in Tris-HCl aqueous solution (concentration 10 mM, pH 8.5) at a material-to-liquid ratio of 1:20 g / mL. Dopamine hydrochloride (98% purity) was then added, and the mixture was stirred for 10 h. After centrifugation, rinsing, and drying, pretreated montmorillonite nanosheets were obtained. The mass ratio of montmorillonite nanosheets to dopamine hydrochloride was 10:1. S22. Pretreated montmorillonite nanosheets were ultrasonically dispersed in deionized water at a material-to-liquid ratio of 1:40 g / mL. Aluminum nitrate was then added, and the mixture was stirred and reacted for 1 hour. After centrifugation, rinsing, and drying, modified montmorillonite nanosheets were obtained. The mass ratio of aluminum nitrate to pretreated montmorillonite nanosheets was 1:35.
[0021] Example 4 The preparation method of modified montmorillonite nanosheets is as follows: S21. Montmorillonite nanosheets (50 nm) were dispersed in Tris-HCl aqueous solution (concentration 10 mM, pH 8.5) at a material-to-liquid ratio of 1:15 g / mL. Dopamine hydrochloride (98% purity) was then added, and the mixture was stirred for 12 h. After centrifugation, rinsing, and drying, pretreated montmorillonite nanosheets were obtained. The mass ratio of montmorillonite nanosheets to dopamine hydrochloride was 12:1. S22. Pretreated montmorillonite nanosheets were ultrasonically dispersed in deionized water at a material-to-liquid ratio of 1:40 g / mL, followed by the addition of aluminum nitrate. After stirring and reacting for 1.5 h, the modified montmorillonite nanosheets were obtained by centrifugation, rinsing and drying. The mass ratio of aluminum nitrate to pretreated montmorillonite nanosheets was 1:30.
[0022] Example 5 A capacitor film for high-temperature applications comprises the following raw materials in parts by weight: 90 parts modified polyimide resin, 15 parts modified montmorillonite nanosheets, 3 parts bismaleimide, and 0.5 parts antioxidant 168.
[0023] The above-mentioned method for preparing capacitor films for high-temperature applications includes the following steps: (1) Modified polyimide resin, modified montmorillonite nanosheets, crosslinking agent, and antioxidant are dispersed in N,N-dimethylacetamide and stirred at 120°C for 2 hours to obtain a mixed slurry; wherein, N,N-dimethylacetamide accounts for 75% of the mass of the mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
[0024] In this embodiment, the modified polyimide resin from Example 1 and the modified montmorillonite nanosheets from Example 4 are used.
[0025] Example 6 A capacitor film for high-temperature applications comprises the following raw materials in parts by weight: 70 parts modified polyimide resin, 25 parts modified montmorillonite nanosheets, 1 part bismaleimide, and 1.5 parts antioxidant 168.
[0026] The above-mentioned method for preparing capacitor films for high-temperature applications includes the following steps: (1) Modified polyimide resin, modified montmorillonite nanosheets, bismaleimide, and antioxidant 168 were dispersed in N,N-dimethylacetamide and stirred at 100°C for 3 hours to obtain a mixed slurry; wherein, N,N-dimethylacetamide accounted for 70% of the mass of the mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
[0027] In this embodiment, the modified polyimide resin from Example 2 and the modified montmorillonite nanosheets from Example 4 are used.
[0028] Example 7 A capacitor film for high-temperature applications comprises the following raw materials in parts by weight: 80 parts modified polyimide resin, 18 parts modified montmorillonite nanosheets, 2 parts bismaleimide, and 1 part antioxidant 168.
[0029] The above-mentioned method for preparing capacitor films for high-temperature applications includes the following steps: (1) Modified polyimide resin, modified montmorillonite nanosheets, bismaleimide, and antioxidant 168 were dispersed in N,N-dimethylacetamide and stirred at 110°C for 2.5 h to obtain a mixed slurry; wherein, N,N-dimethylacetamide accounted for 75% of the mass of the mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
[0030] In this embodiment, the modified polyimide resin from Example 1 and the modified montmorillonite nanosheets from Example 3 are used.
[0031] Comparative Example 1 A capacitor film for high-temperature applications comprises the following raw materials in parts by weight: 80 parts polyimide resin, 18 parts modified montmorillonite nanosheets, 2 parts bismaleimide, and 1 part antioxidant 168.
[0032] The preparation method of the above-mentioned polyimide resin is as follows: S11, 4,4'-diaminodiphenyl ether and N,N-dimethylacetamide are placed in a reactor and stirred to dissolve, and then pyromellitic dianhydride is added and stirred again to obtain a precursor solution; wherein, the mass ratio of 4,4'-diaminodiphenyl ether, pyromellitic dianhydride and N,N-dimethylacetamide is 5:4:60; S12, the precursor solution is subjected to heat treatment to imidize, and the heat treatment is gradient heating, which is carried out successively at 100℃ for 40 min, at 150℃ for 100 min, and at 200℃ for 60 min, during which the heating rate is controlled at 5℃ / min to obtain polyimide resin.
[0033] The above-mentioned method for preparing capacitor films for high-temperature applications includes the following steps: (1) Polyimide resin, modified montmorillonite nanosheets, bismaleimide, and antioxidant 168 were dispersed in N,N-dimethylacetamide and stirred at 110°C for 2.5 h to obtain a mixed slurry; wherein, N,N-dimethylacetamide accounted for 75% of the mass of the mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
[0034] In this comparative example, the modified montmorillonite nanosheets from Example 3 were used.
[0035] Comparative Example 2 A capacitor film for high-temperature applications comprises the following raw materials in parts by weight: 80 parts modified polyimide resin, 18 parts modified montmorillonite nanosheets, 2 parts bismaleimide, and 1 part antioxidant 168.
[0036] The preparation method of modified montmorillonite nanosheets is as follows: S21, montmorillonite nanosheets (50nm) are dispersed in Tris-HCl aqueous solution (concentration of 10mM, pH of 8.5) at a material-to-liquid ratio of 1:20g / mL, followed by the addition of dopamine hydrochloride (purity of 98%), and stirring is continued for 10h. After centrifugation, rinsing and drying, pretreated montmorillonite nanosheets are obtained; wherein, the mass ratio of montmorillonite nanosheets to dopamine hydrochloride is 10:1; S22, the pretreated montmorillonite nanosheets are ultrasonically dispersed in deionized water at a material-to-liquid ratio of 1:40g / mL, and the reaction is stirred for 1h. After centrifugation, rinsing and drying, modified montmorillonite nanosheets are obtained.
[0037] The above-mentioned method for preparing capacitor films for high-temperature applications includes the following steps: (1) Modified polyimide resin, modified montmorillonite nanosheets, bismaleimide, and antioxidant 168 were dispersed in N,N-dimethylacetamide and stirred at 110°C for 2.5 h to obtain a mixed slurry; wherein, N,N-dimethylacetamide accounted for 75% of the mass of the mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
[0038] In this comparative example, the modified polyimide resin from Example 1 was used.
[0039] Comparative Example 3 A capacitor film for high-temperature applications comprises the following raw materials in parts by weight: 80 parts modified polyimide resin, 18 parts montmorillonite nanosheets, 2 parts bismaleimide, and 1 part antioxidant 168.
[0040] The above-mentioned method for preparing capacitor films for high-temperature applications includes the following steps: (1) Modified polyimide resin, montmorillonite nanosheets, bismaleimide, and antioxidant 168 were dispersed in N,N-dimethylacetamide and stirred at 110°C for 2.5 h to obtain a mixed slurry; wherein, N,N-dimethylacetamide accounted for 75% of the mass of the mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
[0041] In this comparative example, the modified polyimide resin from Example 1 was used.
[0042] Performance testing 1. Using the modified polyimide resin in Example 1 and the polyimide resin in Comparative Example 1 as raw materials, the two raw materials were dissolved in N,N-dimethylacetamide and stirred at 110°C for 2.5 h to obtain a mixed slurry; wherein, N,N-dimethylacetamide accounted for 75% of the mass of the mixed slurry; the mixed slurry was subjected to casting, hot pressing crosslinking and peel stretching treatment to obtain a basic film sample with a thickness of 15 μm.
[0043] The capacitor films for high-temperature applications in Examples 5-7 and Comparative Examples 1-3 were used as composite samples (thickness 15 μm).
[0044] The glass transition temperature (Tg) of the basic thin film sample was determined using a differential scanning calorimeter (DSC 2500). gCharacterization was performed under N2 atmosphere protection, with the temperature increased at a rate of 10℃ / min, and the test program temperature ranged from 25 to 400℃. The temperature was then reduced to room temperature (25℃) at a rate of -10℃ / min, and then increased a second time to 400℃ at the same rate. Specific test results are shown in Table 1.
[0045] The breakdown strength of the thin film samples was tested according to GB / T 13542.2-2021 standard (DC conditions, voltage boost rate 500V / s); the dielectric constant and loss factor were tested at 1kHz. Specific test results are shown in Tables 1 and 2.
[0046] Aluminum electrodes were deposited onto the surface of the composite thin film sample by vapor deposition. The energy storage performance of the composite thin film sample with aluminum electrodes was tested using the Radiant Premier II ferroelectric integrated testing system from Radiant Corporation. The test conditions were 150℃ and 500 kV / mm. The specific test and calculation results are shown in Table 2. Table 1 Properties of basic thin film samples As shown in Table 1, compared with Comparative Example 1, the base film sample in Example 1 has higher breakdown strength, lower loss factor and better heat resistance, indicating that the introduction of trifluoromethyl groups into the polyimide molecular chain can improve the performance of the base film.
[0047] Table 2 Properties of Composite Thin Film Samples As shown in Table 2, compared with Example 7, the polyimide resin in Comparative Example 1 does not contain trifluoromethyl groups in its molecular chain, and its breakdown strength and energy storage performance are slightly reduced; the modified montmorillonite nanosheets in Comparative Example 2 did not use aluminum nitrate during preparation, and their breakdown strength and energy storage performance were reduced; the unmodified montmorillonite nanosheets used in Comparative Example 3 had significantly reduced breakdown strength and energy storage performance.
[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A capacitor film for high-temperature applications, characterized in that, The raw materials include the following parts by weight: 70-90 parts modified polyimide resin, 15-25 parts modified montmorillonite nanosheets, 1-3 parts crosslinking agent, and 0.5-1.5 parts antioxidant.
2. The capacitor film for high-temperature applications according to claim 1, characterized in that, The crosslinking agent is selected from bismaleimide; the antioxidant is selected from antioxidant 168.
3. The capacitor film for high-temperature applications according to claim 1, characterized in that, The modified polyimide resin is prepared by: S11. 2,2-Di(trifluoromethyl)diaminobiphenyl and N,N-dimethylacetamide are placed in a reactor and stirred to dissolve. Then, pyromellitic dianhydride is added and stirring is continued to obtain a precursor solution. S12. The precursor solution is heated to imidize it, thereby obtaining a modified polyimide resin.
4. The capacitor film for high-temperature applications according to claim 3, characterized in that, In step S11, the mass ratio of 2,2-bis(trifluoromethyl)diaminobiphenyl, pyromellitic dianhydride and N,N-dimethylacetamide is (4-5):(3-4):(45-60).
5. The capacitor film for high-temperature applications according to claim 3, characterized in that, In step S12, the heating treatment is gradient heating, which involves holding at 100°C for 40 min, at 150°C for 100 min, and at 200°C for 60 min in sequence, while controlling the heating rate to be 5°C / min.
6. The capacitor film for high-temperature applications according to claim 1, characterized in that, The method for preparing the modified montmorillonite nanosheets is as follows: S21. Montmorillonite nanosheets were dispersed in Tris-HCl aqueous solution, followed by the addition of dopamine hydrochloride. After stirring for 10-12 hours, the nanosheets were centrifuged, washed and dried to obtain pretreated montmorillonite nanosheets. S22. Pretreated montmorillonite nanosheets were ultrasonically dispersed in deionized water, followed by the addition of aluminum nitrate. After stirring for 1-1.5 hours, the mixture was centrifuged, rinsed, and dried to obtain modified montmorillonite nanosheets.
7. The capacitor film for high-temperature applications according to claim 6, characterized in that, In step S21, the concentration of the Tris-HCl aqueous solution is 10 mM and the pH is 8.5; the ratio of montmorillonite nanosheets to Tris-HCl aqueous solution is 1:(15-20) g / mL; and the mass ratio of montmorillonite nanosheets to dopamine hydrochloride is (10-12):
1.
8. The capacitor film for high-temperature applications according to claim 6, characterized in that, In step S22, the mass ratio of aluminum nitrate to pretreated montmorillonite nanosheets is 1:(30-35); the material-to-liquid ratio of pretreated montmorillonite nanosheets to deionized water is 1:(40-50) g / mL.
9. The method for preparing a capacitor film for high-temperature applications according to any one of claims 1-8, characterized in that, Includes the following steps: (1) The modified polyimide resin, modified montmorillonite nanosheets, crosslinking agent and antioxidant are dispersed in N,N-dimethylacetamide and stirred at 100-120℃ for 2-3 hours to obtain a mixed slurry; (2) The mixed slurry is cast into a film, hot-pressed crosslinked and peeled and stretched to obtain a capacitor film for high-temperature applications.
10. The method for preparing a capacitor film for high-temperature applications according to claim 9, characterized in that, In step (1), the N,N-dimethylacetamide accounts for 70-75% of the mass of the mixed slurry.