Preparation method and application of high-breakdown polyimide-fluorene polyester insulating composite medium based on strong combination of molecular chain electrostatic acting force

Abstract

The invention discloses a preparation method and application of a high-breakdown polyimide-fluorene polyester insulating composite medium based on molecular chain electrostatic acting force strong combination, and relates to the technical field of polyimide insulating composite media. The invention aims to solve the problem that the improvement of breakdown field strength is limited due to weak interface bonding force when a nano inorganic filler is introduced into a traditional organic / inorganic composite medium. The preparation method comprises the following steps: adding polyimide and fluorene polyester thermoplastic powder into an N-methyl pyrrolidone solution in proportion, sufficiently stirring for a long time at a proper temperature due to the fact that fluorene polyester is relatively difficult to dissolve, and then preparing the polyimide-fluorene polyester insulating composite medium by utilizing a tape casting method after the two polymers are sufficiently mixed. The invention can obtain the preparation method and the application of the high breakdown polyimide-fluorene polyester insulating composite medium based on strong combination of molecular chain electrostatic acting force.

Description

Technical Field

[0001] The invention relates to the technical field of polyimide insulating composite media, and in particular to a preparation method and application of a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces. Background Art

[0002] With the continuous development of modern electronic and power system technology, the application demand of thin film dielectric capacitors in the field of modern electronic and power systems is getting higher and higher. However, the performance of pure polymer dielectrics cannot meet the existing technical requirements. In order to improve the performance of polymer dielectrics, a large number of experiments have been conducted. Researchers have found that the organic / inorganic composite material obtained by incorporating wide bandgap inorganic nanoparticles into organic polymers combines the performance advantages of organic polymer materials and inorganic fillers. By optimizing the selection, ratio and preparation process of organic polymer materials and inorganic fillers, the microstructure and performance of polymer composite dielectrics can be regulated to achieve the improvement and optimization of breakdown performance.

[0003] However, due to the poor compatibility of organic matter and inorganic fillers, the organic-inorganic interface force of the composite medium is weak, which greatly hinders the further improvement of the breakdown performance of the composite medium. Therefore, how to break through this technical barrier has become a technical problem that the industry personnel urgently need to solve. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of weak interface bonding force brought about by the introduction of nano-inorganic fillers in traditional organic / inorganic composite media, which leads to limited improvement in breakdown field strength, and to provide a preparation method and application of a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces.

[0005] A method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces is carried out in the following steps:

[0006] Step S1: preparing a polyimide-fluorene polyester all-organic composite solution;

[0007] Adding polyimide and fluorene polyester thermoplastic powders into N-methylpyrrolidone solution, stirring at a temperature of 70 to 90° C. until the polyimide and fluorene polyester thermoplastic powders are completely dissolved, to obtain a polyimide-fluorene polyester all-organic composite solution; the mass ratio of the polyimide to the fluorene polyester thermoplastic powder is (1:9), (3:7), (5:5), (7:3) or (9:1);

[0008] Step S2: preparing a polyimide-fluorene polyester all-organic insulating composite medium;

[0009] The polyimide-fluorene polyester all-organic composite solution obtained in step S1 is first evacuated, and then evenly coated on the pretreated cast substrate, and then the cast substrate is cured. After curing, the temperature is raised to 200-210°C and kept at 200-210°C for 8-12 hours. After the insulation is completed, the film is peeled off from the cast substrate to obtain a high-breakdown polyimide-fluorene polyester insulating composite medium based on the strong bonding of molecular chain electrostatic forces.

[0010] The invention discloses an application of a high-breakdown polyimide-fluorene polyester insulating composite medium based on a strong combination of molecular chain electrostatic forces, and the application of the high-breakdown polyimide-fluorene polyester insulating composite medium based on a strong combination of molecular chain electrostatic forces in a dielectric capacitor.

[0011] Beneficial effects of the present invention:

[0012] (1) The present invention provides a method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on the strong bonding of molecular chain electrostatic forces. First, polyimide and fluorene polyester thermoplastic powders are added to an N-methylpyrrolidone solution in proportion. Since fluorene polyester is difficult to dissolve, it needs to be fully stirred for a long time at an appropriate temperature. Then, after the two polymers are fully mixed, the polyimide-fluorene polyester insulating composite medium is prepared by a casting method.

[0013] Usually, inorganic nanomaterials with high dielectric constants are introduced into the polymer matrix to form an organic / inorganic polymer composite medium. The weak compatibility between the organic and inorganic phase interfaces leads to a low improvement in the breakdown field strength. The polyimide-fluorene polyester insulating composite medium prepared by the present invention not only has good compatibility, but also because some groups of the polyimide molecular chain are negatively charged and some groups of the fluorene polyester molecular chain are positively charged, strong electrostatic interaction forces realize a tight and compatible phase interface, which greatly improves the breakdown performance and leakage current performance, improves the insulation performance of traditional composite media based on polyimide, solves the problem of high leakage current caused by weak phase interface strength in the composite medium, thereby significantly increasing the breakdown field strength of the composite medium and greatly enhancing the performance stability of the composite medium.

[0014] (2) The polyimide-fluorene polyester insulating composite medium prepared by the process of the present invention has excellent electrical stability and breakdown performance, and can be widely used in advanced fields such as electrical, electronic and new energy vehicles.

[0015] (3) The preparation process of the present invention is simple, economical and practical, effectively saves resources, is suitable for large-scale industrial production, and provides a good strategy for developing new application paths for all-organic insulating composite media.

[0016] The invention can obtain a preparation method and application of a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 represents the Fourier transform infrared spectra of polyimide-fluorene polyester insulating composite dielectrics prepared by using different mass ratios of polyimide and fluorene polyester, a represents pure polyimide film, b represents pure fluorene polyester film, c represents the mass ratio of polyimide to fluorene polyester is 1:9, d represents the mass ratio of polyimide to fluorene polyester is 3:7, e represents the mass ratio of polyimide to fluorene polyester is 5:5, f represents the mass ratio of polyimide to fluorene polyester is 7:3, g represents the mass ratio of polyimide to fluorene polyester is 9:1;

[0018] Figure 2 represents the X-ray diffraction patterns of polyimide-fluorene polyester insulating composite media prepared by using different mass ratios of polyimide and fluorene polyester, a represents pure polyimide film, b represents pure fluorene polyester film, c represents the mass ratio of polyimide to fluorene polyester is 1:9, d represents the mass ratio of polyimide to fluorene polyester is 3:7, e represents the mass ratio of polyimide to fluorene polyester is 5:5, f represents the mass ratio of polyimide to fluorene polyester is 7:3, g represents the mass ratio of polyimide to fluorene polyester is 9:1;

[0019] Figure 3 It represents the Weibull distribution spectrum of the breakdown field strength of the polyimide-fluorene polyester insulating composite medium prepared by using different mass ratios of polyimide and fluorene polyester, ■ represents pure polyimide film, ● represents pure fluorene polyester film, ▲ represents the mass ratio of polyimide to fluorene polyester is 1:9, ▼ represents the mass ratio of polyimide to fluorene polyester is 3:7, ◆ represents the mass ratio of polyimide to fluorene polyester is 5:5, It means that the mass ratio of polyimide to fluorene polyester is 7:3. It means that the mass ratio of polyimide to fluorene polyester is 9:1;

[0020] Figure 4 It represents the leakage current test spectrum of the polyimide-fluorene polyester insulating composite medium prepared by using different mass ratios of polyimide and fluorene polyester, ■ represents pure polyimide film, ● represents pure fluorene polyester film, ▲ represents the mass ratio of polyimide to fluorene polyester is 1:9, ▼ represents the mass ratio of polyimide to fluorene polyester is 3:7, ◆ represents the mass ratio of polyimide to fluorene polyester is 5:5, It means that the mass ratio of polyimide to fluorene polyester is 7:3. It means that the mass ratio of polyimide to fluorene polyester is 9:1;

[0021] Figure 5Figure 5 represents the differential scanning calorimetry spectra of polyimide-fluorene polyester insulating composite media prepared by using different mass ratios of polyimide and fluorene polyester, a represents the mass ratio of polyimide to fluorene polyester is 1:9, b represents pure fluorene polyester film, c represents pure polyimide film, d represents the mass ratio of polyimide to fluorene polyester is 7:3, e represents the mass ratio of polyimide to fluorene polyester is 9:1, f represents the mass ratio of polyimide to fluorene polyester is 5:5, and g represents the mass ratio of polyimide to fluorene polyester is 3:7. DETAILED DESCRIPTION

[0022] Specific implementation method 1: This implementation method is a method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic force of molecular chains, which is carried out according to the following steps:

[0023] Step S1: preparing a polyimide-fluorene polyester all-organic composite solution;

[0024] Adding polyimide and fluorene polyester thermoplastic powders into N-methylpyrrolidone solution, stirring at a temperature of 70 to 90° C. until the polyimide and fluorene polyester thermoplastic powders are completely dissolved, to obtain a polyimide-fluorene polyester all-organic composite solution; the mass ratio of the polyimide to the fluorene polyester thermoplastic powder is (1:9), (3:7), (5:5), (7:3) or (9:1);

[0025] Step S2: preparing a polyimide-fluorene polyester all-organic insulating composite medium;

[0026] The polyimide-fluorene polyester all-organic composite solution obtained in step S1 is first evacuated, and then evenly coated on the pretreated cast substrate, and then the cast substrate is cured. After curing, the temperature is raised to 200-210°C and kept at 200-210°C for 8-12 hours. After the insulation is completed, the film is peeled off from the cast substrate to obtain a high-breakdown polyimide-fluorene polyester insulating composite medium based on the strong bonding of molecular chain electrostatic forces.

[0027] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that before adding the polyimide and fluorene polyester thermoplastic powders into the N-methylpyrrolidone solution in step S1, they are first kept warm under vacuum conditions at 50-60°C for 7-8h.

[0028] The other steps are the same as those in the first specific implementation.

[0029] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that: in step S1, the ratio of the total mass of polyimide and fluorene polyester thermoplastic powder to the volume of N-methylpyrrolidone solution is (1-1.2) g: (10-12) mL.

[0030] The other steps are the same as those in the first or second embodiment.

[0031] Specific embodiment 4: The difference between this embodiment and specific embodiments 1 to 3 is that in step S2, the vacuumized polyimide-fluorene polyester all-organic composite solution is first allowed to stand for 1 to 2 hours, and then evenly coated on the pre-treated casting substrate.

[0032] The other steps are the same as those in Specific Embodiments 1 to 3.

[0033] Specific implementation mode five: The difference between this implementation mode and specific implementation modes one to four is that the pretreated cast substrate described in step S2 is processed according to the following steps: first, the cast substrate is ultrasonically cleaned in deionized water for 1 to 3 times, then wiped clean with dust-free paper, and then placed in a vacuum oven at 50 to 60°C to dry, and finally rinsed with anhydrous ethanol for 3 to 5 times and dried to obtain a pretreated cast substrate.

[0034] The other steps are the same as those in Specific Embodiments 1 to 4.

[0035] Specific implementation method 6: The difference between this implementation method and specific implementation methods 1 to 5 is that the cast substrate is tempered glass.

[0036] The other steps are the same as those in Specific Embodiments 1 to 5.

[0037] Specific embodiment 7: The difference between this embodiment and specific embodiments 1 to 6 is that in step S2, the cast substrate is first placed in a vacuum oven for preheating for 2 to 3 hours, and then cured.

[0038] The other steps are the same as those in Specific Embodiments 1 to 6.

[0039] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that the curing temperature in step S2 is 80-85°C.

[0040] The other steps are the same as those in Specific Embodiments 1 to 7.

[0041] Specific embodiment 9: The difference between this embodiment and specific embodiments 1 to 8 is that after the insulation in step S2 is completed, the cast substrate is first placed in deionized water at 60 to 80° C. and soaked for 10 to 15 minutes, and then the film is peeled off from the cast substrate.

[0042] The other steps are the same as those in Specific Embodiments 1 to 8.

[0043] Specific embodiment ten: This embodiment provides an application of a high breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic force of molecular chains, and the application of the high breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic force of molecular chains in dielectric capacitors.

[0044] The following examples are used to verify the beneficial effects of the present invention:

[0045] Example 1: A method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic forces of molecular chains, which is carried out according to the following steps:

[0046] Step S1: preparing a polyimide-fluorene polyester all-organic composite solution;

[0047] First, 0.1 g of polyimide and 0.9 g of fluorene polyester thermoplastic powder were kept at 50°C under vacuum for 7 hours, then added into 10 mL of N-methylpyrrolidone solution, and stirred at 80°C until the polyimide and fluorene polyester thermoplastic powder were completely dissolved to obtain a polyimide-fluorene polyester all-organic composite solution;

[0048] The step S2: preparing a polyimide-fluorene polyester all-organic insulating composite medium;

[0049] A casting substrate with a size of 200 mm×16 mm×4 mm was prepared, and the casting substrate was first ultrasonically cleaned 3 times in deionized water, and then wiped clean with dust-free paper, and then placed in a vacuum oven to dry at 50° C., and finally rinsed with anhydrous ethanol 3 times and dried to obtain a pretreated casting substrate, wherein the casting substrate was tempered glass;

[0050] The polyimide-fluorene polyester all-organic composite solution obtained in step S1 is first evacuated, allowed to stand for 1 hour after evacuation, and then evenly coated on the pretreated cast substrate, placed in a vacuum oven for preheating for 2 hours, and then the cast substrate is cured at 80°C, and then heated to 200°C after curing, and kept warm at 200°C for 10 hours. After the insulation is completed, the cast substrate is first placed in 60°C deionized water, soaked for 15 minutes, and then the film is peeled off from the cast substrate to obtain a high breakdown polyimide-fluorene polyester insulating composite medium based on the strong bonding of molecular chain electrostatic forces.

[0051] Example 2: In this example, the weights of the polyimide and fluorene polyester thermoplastic powders are 0.3 g and 0.7 g respectively. Other experimental conditions are the same as those in Example 1.

[0052] Example 3: In this example, the weights of the polyimide and fluorene polyester thermoplastic powders are 0.5 g and 0.5 g respectively. Other experimental conditions are the same as those in Example 1.

[0053] Example 4: In this example, the weights of the polyimide and fluorene polyester thermoplastic powders are 0.7 g and 0.3 g respectively. Other experimental conditions are the same as those in Example 1.

[0054] Example 5: In this example, the weights of the polyimide and fluorene polyester thermoplastic powders are 0.9 g and 0.1 g respectively. Other experimental conditions are the same as those in Example 1.

[0055] Comparative Example 1: In this comparative example, no fluorene polyester thermoplastic powder is added. Other experimental conditions are the same as those in Example 1.

[0056] Comparative Example 2: In this comparative example, no polyimide thermoplastic powder is added. Other experimental conditions are the same as those in Example 1.

[0057] Figure 1 The figures represent the Fourier transform infrared spectra of polyimide-fluorene polyester insulating composite media prepared by using different mass ratios of polyimide and fluorene polyester, a represents pure polyimide film, b represents pure fluorene polyester film, c represents the mass ratio of polyimide to fluorene polyester is 1:9, d represents the mass ratio of polyimide to fluorene polyester is 3:7, e represents the mass ratio of polyimide to fluorene polyester is 5:5, f represents the mass ratio of polyimide to fluorene polyester is 7:3, and g represents the mass ratio of polyimide to fluorene polyester is 9:1.

[0058] like Figure 1 As shown, the polyimide matrix is ​​at 1780 cm -1 、1710cm -1 and 1366cm -1 There are corresponding characteristic absorption peaks at 1780cm -1 The absorption peak at 1725 cm is the asymmetric vibration of C=O. -1 The absorption peak at 1500 cm -1 The absorption peak at 880 cm-1 corresponds to the benzene ring. -1 The absorption peak at 725 cm corresponds to CN stretching. -1 It is C=O bending vibration. The characteristic peak corresponding to fluorene polyester appears at 1742cm -1 The characteristic peaks of both materials appeared in the polyimide-fluorene polyester insulating composite medium at the same time, and the intensity was obvious, indicating that the fully organic composite medium based on the different charged groups of the two polymer molecular chains was successfully prepared and had excellent interface strength.

[0059] Figure 2 Figure 3 represents the X-ray diffraction patterns of polyimide-fluorene polyester insulating composite media prepared by using different mass ratios of polyimide and fluorene polyester, a represents pure polyimide film, b represents pure fluorene polyester film, c represents the mass ratio of polyimide to fluorene polyester is 1:9, d represents the mass ratio of polyimide to fluorene polyester is 3:7, e represents the mass ratio of polyimide to fluorene polyester is 5:5, f represents the mass ratio of polyimide to fluorene polyester is 7:3, and g represents the mass ratio of polyimide to fluorene polyester is 9:1.

[0060] like Figure 2 As shown, the diffuse scattering peak of polyimide is around 20°, the diffuse scattering peak of fluorene polyester is around 25°, and the diffuse scattering peak of polyimide-fluorene polyester insulating composite medium is between 20-25°, indicating that the composite material has the characteristics of both polyimide and fluorene polyester. At the same time, the curve of the polyimide-fluorene polyester insulating composite medium is smooth, and no other characteristic crystallization peaks appear.

[0061] Figure 3 It represents the Weibull distribution spectrum of the breakdown field strength of the polyimide-fluorene polyester insulating composite medium prepared by using different mass ratios of polyimide and fluorene polyester, ■ represents pure polyimide film, ● represents pure fluorene polyester film, ▲ represents the mass ratio of polyimide to fluorene polyester is 1:9, ▼ represents the mass ratio of polyimide to fluorene polyester is 3:7, ◆ represents the mass ratio of polyimide to fluorene polyester is 5:5, It means that the mass ratio of polyimide to fluorene polyester is 7:3. It means that the mass ratio of polyimide to fluorene polyester is 9:1.

[0062] like Figure 3 As shown in the figure, the breakdown of polyimide is 468kV / mm, the breakdown of fluorene polyester is 556kV / mm, the breakdown of polyimide / fluorene polyester all-organic insulating composite medium is 605kV / mm at the lowest and 767kV / mm at the highest; the trend is first increasing and then decreasing, among which the composite material with a mass ratio of polyimide to fluorene polyester of 5:5 has the highest breakdown. At the same time, it can be seen that the breakdown field strength of the all-organic insulating composite medium is significantly improved compared with that of the pure polymer, indicating that the strong interface caused by the electrostatic interaction force has a positive effect on the breakdown performance of the polymer medium.

[0063] Figure 4 It represents the leakage current test spectrum of the polyimide-fluorene polyester insulating composite medium prepared by using different mass ratios of polyimide and fluorene polyester, ■ represents pure polyimide film, ● represents pure fluorene polyester film, ▲ represents the mass ratio of polyimide to fluorene polyester is 1:9, ▼ represents the mass ratio of polyimide to fluorene polyester is 3:7, ◆ represents the mass ratio of polyimide to fluorene polyester is 5:5, It means that the mass ratio of polyimide to fluorene polyester is 7:3. It means that the mass ratio of polyimide to fluorene polyester is 9:1.

[0064] like Figure 4 As shown, the leakage current of polyimide is the highest, indicating that it has more conductive paths under the action of the electric field. As the proportion of fluorene polyester in the film increases, the leakage current of the polyimide-fluorene polyester insulating composite medium gradually decreases. Subsequently, the conductive path of the composite medium gradually decreases under the action of the electric field, and its stability improves accordingly.

[0065] Figure 5Figure 5 represents the differential scanning calorimetry spectra of polyimide-fluorene polyester insulating composite media prepared by using different mass ratios of polyimide and fluorene polyester, a represents the mass ratio of polyimide to fluorene polyester is 1:9, b represents pure fluorene polyester film, c represents pure polyimide film, d represents the mass ratio of polyimide to fluorene polyester is 7:3, e represents the mass ratio of polyimide to fluorene polyester is 9:1, f represents the mass ratio of polyimide to fluorene polyester is 5:5, and g represents the mass ratio of polyimide to fluorene polyester is 3:7.

[0066] like Figure 5 As shown in the figure, as the content of polyimide in the polyimide-fluorene polyester insulating composite medium increases, its glass transition temperature also increases, indicating that the thermal stability gradually becomes stronger. In addition, all polyimide-fluorene polyester insulating composite media only have one melting peak, indicating that polyimide and fluorene polyester are well combined due to strong electrostatic interaction and have strong compatibility.

Claims

1. A method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic forces of molecular chains, characterized in that The preparation method is carried out according to the following steps: Step S1: preparing a polyimide-fluorene polyester all-organic composite solution; Adding polyimide and fluorene polyester thermoplastic powders into N-methylpyrrolidone solution, stirring at a temperature of 70 to 90° C. until the polyimide and fluorene polyester thermoplastic powders are completely dissolved, to obtain a polyimide-fluorene polyester all-organic composite solution; the mass ratio of the polyimide to the fluorene polyester thermoplastic powder is (1:9), (3:7), (5:5), (7:3) or (9:1); Step S2: preparing a polyimide-fluorene polyester all-organic insulating composite medium; The polyimide-fluorene polyester all-organic composite solution obtained in step S1 is first evacuated, and then evenly coated on the pretreated cast substrate, and then the cast substrate is cured. After curing, the temperature is raised to 200-210°C and kept at 200-210°C for 8-12 hours. After the insulation is completed, the film is peeled off from the cast substrate to obtain a high-breakdown polyimide-fluorene polyester insulating composite medium based on the strong bonding of molecular chain electrostatic forces.

2. The method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic interaction of molecular chains according to claim 1, characterized in that Before adding the polyimide and fluorene polyester thermoplastic powders into the N-methylpyrrolidone solution in step S1, the solution is first kept warm under vacuum conditions at 50-60° C. for 7-8 hours.

3. A method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces according to claim 1 or 2, characterized in that In step S1, the ratio of the total mass of the polyimide and fluorene polyester thermoplastic powder to the volume of the N-methylpyrrolidone solution is (1-1.2) g: (10-12) mL.

4. The method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic interaction of molecular chains according to claim 1, characterized in that In step S2, the vacuumized polyimide-fluorene polyester all-organic composite solution is first allowed to stand for 1 to 2 hours, and then evenly coated on the pre-treated casting substrate.

5. A method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces according to claim 1 or 4, characterized in that The pretreated cast substrate described in step S2 is treated according to the following steps: first, the cast substrate is ultrasonically cleaned in deionized water for 1 to 3 times, then wiped clean with dust-free paper, placed in a vacuum oven at 50 to 60°C for drying, and finally rinsed with anhydrous ethanol for 3 to 5 times and dried to obtain a pretreated cast substrate.

6. The method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces according to claim 5, characterized in that The cast glass substrate is tempered glass.

7. The method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic interaction of molecular chains according to claim 1, characterized in that In step S2, the cast substrate is first placed in a vacuum oven for preheating for 2 to 3 hours and then cured.

8. A method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces according to claim 1 or 7, characterized in that The curing temperature in step S2 is 80-85°C.

9. The method for preparing a high-breakdown polyimide-fluorene polyester insulating composite medium based on strong bonding of molecular chain electrostatic forces according to claim 1, characterized in that After the heat preservation in step S2 is completed, the casting substrate is first placed in deionized water at 60-80° C. and soaked for 10-15 minutes, and then the film is peeled off from the casting substrate.

10. The use of a high breakdown polyimide-fluorene polyester insulating composite medium based on strong electrostatic force of molecular chains as described in any one of claims 1 to 9, characterized in that The high breakdown polyimide-fluorene polyester insulating composite medium based on the strong bonding of molecular chain electrostatic forces is used in dielectric capacitors.

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