All-organic dielectric insulating material as well as preparation method and application thereof

Abstract

The invention discloses an all-organic dielectric insulating material as well as a preparation method and application thereof, and belongs to the technical field of functional polymer composite materials and preparation thereof. The problem that the insulating property of an existing insulating material is degraded at the temperature of 150 DEG C is solved. Construction of a nanoscale seven-layer energy level gradient confinement valley is achieved through a three-layer macroscopic concentration gradient structure, a PEI-F2-N0.05 blend with the PESU concentration of 20% is adopted in the middle layer, a deep energy level valley core region is matched, and the charge confinement effect is enhanced; the interface layers on the two sides are made of a PEI-F2-N 0.05 blend with the PESU concentration of 10%, a shallow energy level valley slope region is matched, electric field distortion is restrained, and an electric field is differentiated. Experimental results show that the insulating strength of the material reaches 600MV / m or above at the high temperature of 150 DEG C.

Description

Technical Field

[0001] This invention relates to an all-organic dielectric insulating material, its preparation method, and its application, belonging to the technical field of functional polymer composite materials and their preparation. Background Technology

[0002] With the popularization of ultra-high voltage direct current transmission systems and 800V platforms for new energy vehicles, insulation materials for electrical equipment face extreme working conditions: they need to achieve a breakdown field strength of ≥600MV / m and low loss at high frequency (tanδ≤0.005 at 150kHz) at a high temperature of 150℃.

[0003] However, existing insulating materials suffer from three irreconcilable contradictions: 1. Carrier control failure: While relying on a single deep-level trap can capture carriers, its activation energy is generally low, leading to an excessively high detrapping rate at 150℃, making deep confinement impossible and causing carrier runaway; 2. Multi-scale structural defects: At the nanoscale, disordered distribution of functional units causes energy level dispersion, resulting in tortuous carrier confinement paths and a surge in escape probability; at the macroscale, traditional layered composite materials (such as sandwich structures) suffer from interfacial porosity due to physical stacking, inducing local electric field distortion; 3. Fragmentation of functional synergy: Existing modification strategies (such as inorganic filler composites and random blending toughening) design nanoscale energy level gradients and macroscale concentration gradients independently, lacking a synergistic mechanism, making the macroscale concentration gradient and nanoscale energy level gradient designs independent of each other, lacking a cross-scale coupling mechanism; resulting in low insulation performance of existing insulating materials at 150℃ and a sharp decline in high-frequency performance.

[0004] Therefore, there is an urgent need to develop a design strategy for all-organic dielectric insulating materials with precise matching of nanoscale energy level and macroscopic concentration dual gradients, in order to break through the bottleneck of synergistic optimization of carrier confinement depth and interface compatibility. Summary of the Invention

[0005] This invention addresses the problem of insulation performance degradation of existing insulating materials at 150°C by providing a high-temperature resistant insulating material, its preparation method, and its application.

[0006] The technical solution of the present invention: One objective of this invention is to provide a method for preparing an all-organic dielectric insulating material, the method comprising the following steps: (1) Under vacuum, 0-5℃ and inert atmosphere protection, fluorinated diamine, nitro diamine and ODA are dissolved in a dehydrated and deoxygenated polar aprotic solvent and stirred for 15-30 min to obtain a diamine solution; (2) Under vacuum, 0-5℃ and inert atmosphere protection, BPADA powder was added in batches to the diamine solution of (1), and the reaction was stirred for 5-6 h to obtain PAA-F2-N. 0.05solution solution; (3) At 15-25℃, the same mass of PAA-F2-N was subjected to the same treatment. 0.05 Different masses of PESU were added to the solution and stirred for 10-16 hours to obtain blended solutions with different PESU mass ratios. (4) When the vacuum degree is ≤10 -3 At Pa and room temperature, the blended solution is subjected to stepwise degassing treatment, and then a film is coated by solution casting method. First, the bottom layer is coated, the middle layer is coated immediately after pre-imidization treatment, and finally the top layer is coated. The resulting wet film is subjected to complete thermal imidization treatment to obtain an all-organic dielectric insulating material. The bottom and top layers are blended solutions with the same mass percentage of PESU, and the mass percentage of PESU used to prepare the middle layer blended solution is twice that used to prepare the bottom layer blended solution.

[0007] Further specifying, in (1), the polar aprotic solvent is DMAC.

[0008] Further specified, (1) the ratio of the total molar amount of all diamine monomers in the obtained diamine solution to the molar amount of BPADA is 1:1.008-1:015.

[0009] Further specified, (1) the fluorinated diamine accounts for 1.8-2.2% of the total molar amount of all diamine monomers, the nitro diamine accounts for 0.04-0.06% of the total molar amount of all diamine monomers, and the molar ratio of the fluorinated diamine to the nitro diamine is 0.09-0.11.

[0010] Further, (3) the solid content of the blended solutions with different PESU mass ratios is 18-22 wt%.

[0011] Further restrictions are imposed, (4) the conditions for the intermediate coating are: ultra-dry inert atmosphere, relative humidity ≤1%, oxygen content ≤1ppm.

[0012] Further, in (4), the wet film thickness is 4-9 μm, and the thickness of the bottom layer, the middle layer and the top layer are the same.

[0013] Further specified, (4) the pre-iminoization process is as follows: heat to 80℃ at 1℃ / min and hold for 5.5-6.5h, then heat to 100℃ at 2℃ / min and hold for 0.8-1.2h; the complete thermal iminoization process is as follows: heat to 80℃ at 1℃ / min and hold for 5.5-6.5h, then heat to 100℃ at 2℃ / min and hold for 0.8-1.2h, then heat to 150℃ at 3℃ / min and hold for 0.8-1.2h, then heat to 200℃ at 5℃ / min and hold for 0.8-1.2h, and finally heat to 275±2℃ at 8℃ / min and hold for 0.8-1.2h.

[0014] The second objective of this invention is to provide an all-organic dielectric insulating material prepared by the above method, specifically, the insulating material has a nanoscale seven-layer energy level gradient confinement valley, and a breakdown field strength ≥600MV / m at 150℃.

[0015] The third objective of this invention is to provide an application of the above-mentioned all-organic dielectric insulating material, specifically for insulation of high-voltage electrical equipment and new energy vehicles with an operating environment temperature ≥125℃ and an operating field strength ≥300MV / m.

[0016] Beneficial effects: This invention constructs a three-layer polyimide system with macroscopic concentration gradients using fluorinated diamine, nitrodiamine, and ODA as diamine monomers, BPADA as a dianhydride monomer, and PESU as a blend. By controlling the proportions of fluorinated and nitrodiamines in the diamine monomers and the PESU blend concentration in each layer, a seven-layer energy level gradient confinement valley is constructed. This achieves a synergistic control mechanism between the nano-level energy level gradient confinement valley and the macroscopic concentration gradient, breaking through the high-temperature insulation performance limit and achieving an insulation strength of over 600 MV / m at 150℃. Compared with existing technologies, it has at least the following advantages: (1) The all-organic dielectric insulating material provided by the present invention has three macroscopic concentration gradients, wherein the middle functional layer adopts PEI-F2-N with a concentration of 20% PESU. 0.05 The blend is matched to the deep-level valley core region to enhance the charge confinement effect; the interface layers on both sides use PEI-F2-N with a concentration of 10% PESU. 0.05 The blends match the shallow energy level valley slope region, suppressing electric field distortion and differentiating the electric field.

[0017] (2) The all-organic dielectric insulating material provided by this invention has a nanoscale seven-layer energy level gradient structure. The energy level distribution satisfies the existence of energy level differences between adjacent layers, and the energy levels from high to low are as follows: the first and seventh layers are electron injection and escape barrier layers mainly contributed by PESU; the second and sixth layers are secondary barrier level transition layers mainly contributed by the PEI matrix; the third and fifth layers are shallow trap / hole confinement layers mainly contributed by fluorine (-F) functional groups; and the fourth layer is a deep trap / electron capture core layer mainly contributed by nitro (-NO2) functional groups. By combining the "confinement valley" formed by the seven-layer continuous energy level gradient with the multi-layer concentration gradient, the high-temperature insulation performance limit is broken. Attached Figure Description

[0018] Figure 1 XRD comparison spectra of the insulating materials prepared in Comparative Examples 1-5; Figure 2 XRD comparison spectra of the insulating materials prepared in Examples 1-4; Figure 3 Infrared spectra of the insulating materials prepared in Comparative Examples 1-5; Figure 4 Infrared spectra of the insulating materials prepared in Comparative Examples 1-4; Figure 5 Leakage current density diagrams of the insulating materials prepared in Comparative Examples 1-5; Figure 6 Leakage current density diagrams of the insulating materials prepared in Examples 1-4; Figure 7 The breakdown results of the insulating materials prepared in Comparative Examples 1-5 are shown in the figure. Figure 8 The diagram shows the breakdown results of the insulating materials prepared in Examples 1-4. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art may make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0023] The 4,4'-diaminodiphenyl ether (C) used in the following examples 12 H 12 N2O, ODA); 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride (C 31 H 20 O8, BPADA); the fluorinated diamine is 4,4'-diaminooctafluorobiphenyl (C 12 H4F8N2, 8F-BDA); containing nitrodiamine as 4-nitro-o-phenylenediamine (C6H7N3O2, 4N-OP); polyethersulfone (C 10H8O2 (PESU) has a rigid framework structure consisting of aromatic rings linked by alternating ether bonds and sulfone groups; the solvent is N,N-dimethylacetamide (DMAC).

[0024] Comparative Example 1: This comparative example prepares the insulating material PEI-F2-N. 0.05 The method using 20% ​​PESU includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 20 min.

[0025] Step 2: Under the same low temperature and inert atmosphere conditions as in Step 1, 1.843475 g of BPADA powder was slowly added to the solution in Step 1 in four batches. The addition rate was controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature is controlled at 15-25℃, and the mixture is stirred continuously for 15 hours to ensure that a homogeneous, stable, and phase-separation-free blend solution is obtained (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups and 20% wt PESU).

[0026] Step 3: Place the blended solution obtained in Step 2 under a vacuum of ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0027] Step 4: The degassed solution obtained in Step 3 is subjected to a casting coating process in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm). A precision doctor blade is used to control the wet film thickness within 5 μm. During coating, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0028] Step 5: The wet film obtained in Step 4 is subjected to an imidization drying heating process in an oven. The specific temperature program is as follows: heat to 80℃ at 1℃ / min and hold for 5 hours, then heat to 100℃ at 2℃ / min and hold for 1 hour, then heat to 150℃ at 3℃ / min and hold for 1 hour, then heat to 200℃ at 5℃ / min and hold for 1 hour, and finally heat to 275±2℃ at 8℃ / min and hold for 1 hour.

[0029] Step 6: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process. Finally, the insulating material is obtained and named PEI-F2-N. 0.05 / 20%PESU.

[0030] Comparative Example 2: The insulating material prepared in this comparative example has a three-layer structure, with the middle layer being PEI-F2-N. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 / 20% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0031] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.071143 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and the mixture was stirred continuously for 15 hours to obtain a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups and 10% PESU), named PAA-F2-N. 0.05 / 10%PESU.

[0032] Step 2: Under vacuum (-0.1 MPa), deep cryogenic (5°C), and inert atmosphere protection, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0033] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and the mixture was continuously stirred for 15 hours to ensure the formation of a cross-linked network, resulting in a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0034] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 10%PESU and PAA-F2-N 0.05 / 20% PESU is all in a vacuum degree ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0035] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0036] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A base coat of 20% PESU was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the base coat. 0.05 A 10% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 20% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0037] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 / 10% PESU, with PEI-F2-N on both sides 0.05 The three-layer structure of 20% PESU is named 20-10-20.

[0038] Comparative Example 3: The insulating material prepared in this comparative example has a three-layer structure, with the middle layer being PEI-F2-N. 0.05 30% PESU, with PEI-F2-N on both sides. 0.05 / 20% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0039] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.213429 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and the mixture was stirred continuously for 15 hours to obtain a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups and 30% PESU), named PAA-F2-N. 0.05 / 30%PESU.

[0040] Step 2: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0041] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and the mixture was stirred continuously for 15 hours to obtain a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups and 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0042] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 30%PESU and PAA-F2-N 0.05 / 20% PESU is all in a vacuum degree ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0043] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0044] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A base coat of 20% PESU was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the base coat. 0.05 A 30% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 20% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0045] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 30% PESU, with PEI-F2-N on both sides. 0.05 The three-layer structure of 20% PESU is named 20-30-20.

[0046] Comparative Example 4: The insulating material prepared in this comparative example has a three-layer structure, with the middle layer being PEI-F2-N. 0.05 40% PESU, with PEI-F2-N on both sides. 0.05 / 20% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0047] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.284572 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 30% PESU), named PAA-F2-N. 0.05 / 40%PESU.

[0048] Step 2: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0049] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0050] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 40%PESU and PAA-F2-N 0.05 / 20% PESU is all within a vacuum level ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0051] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0052] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A base coat of 20% PESU was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the base coat. 0.05 A 40% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 20% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0053] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 40% PESU, with PEI-F2-N on both sides. 0.05 The three-layer structure of 20% PESU is named 20-40-20.

[0054] Comparative Example 5: The insulating material prepared in this comparative example has a three-layer structure, with the middle layer being PEI-F2-N. 0.05 50% PESU, with PEI-F2-N on both sides. 0.05 / 20% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0055] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.355715 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 30% PESU), named PAA-F2-N. 0.05 / 50% PESU.

[0056] Step 2: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0057] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and the mixture was continuously stirred for 15 hours to ensure the formation of a cross-linked network, resulting in a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0058] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 50%PESU and PAA-F2-N 0.05 / 20% PESU is all in a vacuum degree ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0059] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0060] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A base coat of 20% PESU was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the base coat. 0.05 A 50% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 20% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0061] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 50% PESU, with PEI-F2-N on both sides. 0.05 The three-layer structure of 20% PESU is named 20-50-20.

[0062] Example 1: In this embodiment, the insulating material is prepared with a three-layer structure, wherein the middle layer is PEI-F2-N. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 / 10% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0063] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.071143 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 30% PESU), named PAA-F2-N. 0.05 / 10%PESU.

[0064] Step 2: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0065] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0066] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 10%PESU and PAA-F2-N 0.05 / 20% PESU is all in a vacuum degree ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0067] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0068] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A 10% PESU undercoat was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the undercoat. 0.05 A 20% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 10% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0069] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 The three-layer structure of 10% PESU is named 10-20-10.

[0070] Example 2: In this embodiment, the insulating material is prepared with a three-layer structure, wherein the middle layer is PEI-F2-N. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 / 30% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0071] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.213429 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 30% PESU), named PAA-F2-N. 0.05 / 30%PESU.

[0072] Step 2: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0073] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0074] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 30%PESU and PAA-F2-N 0.05 / 20% PESU is all in a vacuum degree ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0075] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0076] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A base coat of 30% PESU was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the base coat. 0.05 A 20% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 30% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0077] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 The three-layer structure of 30% PESU is named 30-20-30.

[0078] Example 3: In this embodiment, the insulating material is prepared with a three-layer structure, wherein the middle layer is PEI-F2-N. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 / 40% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0079] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.284572 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 30% PESU), named PAA-F2-N. 0.05 / 40%PESU.

[0080] Step 2: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0081] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0082] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 40%PESU and PAA-F2-N 0.05 / 20% PESU is all in a vacuum degree ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0083] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0084] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A base coat of 40% PESU was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the base coat. 0.05 A 20% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 40% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0085] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 / The three-layer structure of 40% PESU is named 40-20-40.

[0086] Example 4: In this embodiment, the insulating material is prepared with a three-layer structure, wherein the middle layer is PEI-F2-N. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 / 50% PESU, the specific preparation method includes the following steps: Step 1: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0087] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.355715 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 30% PESU), named PAA-F2-N. 0.05 / 50% PESU.

[0088] Step 2: Under vacuum (-0.1 MPa) and deep cryogenic (5°C) conditions, weigh 0.000268511 g of 4-nitro-o-phenylenediamine, 0.023016 g of 4,4'-diaminooctafluorobiphenyl, and 0.6881457 g of 4,4'-diaminodiphenyl ether (ODA) and dissolve them in 15 ml of N,N-dimethylacetamide (DMAC) solvent. Perform low-temperature monomer activation and stirring for 25 min.

[0089] Then, BPADA powder, totaling 1.843475 g, was slowly added to the solution in four batches, with the addition rate controlled to keep the system temperature fluctuation ≤ ±1℃. The reaction was carried out for 2 hours under mechanical stirring at 250 rpm to obtain PAA-F2-N. 0.05 Solution. 0.142286 g of PESU granules, dried at 60°C for 24 h, was slowly added to PAA-F2-N. 0.05 In the solution, the blending temperature was controlled at 15-25℃, and stirring was continued for 15 hours to ensure a homogeneous, stable, and phase-separation-free blend solution (a blend solution of PAA containing 2% perfluorinated groups and 0.05% nitro groups with 20% PESU), named PAA-F2-N. 0.05 / 20%PESU.

[0090] Step 3: Take the blended solution PAA-F2-N obtained in Step 2. 0.05 / 50%PESU and PAA-F2-N 0.05 / 20% PESU is all in a vacuum degree ≤10 -3 The gas was degassed at room temperature for 6 hours to completely eliminate microbubbles.

[0091] Step 4: The degassed solution obtained in Step 3 is cast into a film in an ultra-dry inert atmosphere (oxygen content < 0.1 ppm, water content < 0.1 ppm) chamber. During the coating process, the temperature of the precursor solution is controlled at 20 ± 0.5 ℃ and the viscosity is controlled at 2500 ± 200 cP.

[0092] The specific process of casting film is as follows: First, use PAA-F2-N 0.05 A base coat of 50% PESU was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade. Pre-imidization was then performed in an oven (increasing to 80℃ at 1℃ / min and holding for 6 hours, then increasing to 100℃ at 2℃ / min and holding for 1 hour). Immediately afterwards, PAA-F2-N was applied to the base coat. 0.05 A 20% PESU intermediate layer was applied, with the casting thickness controlled to 2±0.2μm using a precision doctor blade; finally, PAA-F2-N was applied to the intermediate layer. 0.05 A top coat of 50% PESU was applied, and the thickness of the tape was controlled to 2±0.2μm using a precision doctor blade. The entire tape was then subjected to complete imidization treatment in an oven (heating to 80℃ at 1℃ / min and holding for 6h, then heating to 100℃ at 2℃ / min and holding for 1h, then heating to 150℃ at 3℃ / min and holding for 1h, then heating to 200℃ at 5℃ / min and holding for 1h, and finally heating to 275±2℃ at 8℃ / min and holding for 1h).

[0093] Step 5: The film is peeled off under the assistance of deionized water at 40℃ and ultrasound. Then, a dual-temperature airflow control technology is used for drying. Specifically, after evacuating the oven, argon gas is introduced, and the upper temperature is set to 80℃ while the lower temperature is set to 60℃. Thermal convection is used to create a self-equilibrium field to accelerate the drying process, ultimately obtaining a PEI-F2-N intermediate layer. 0.05 20% PESU, with PEI-F2-N on both sides. 0.05 The three-layer structure of 50% PESU is named 50-20-50.

[0094] Example of results: (1) Comparative XRD spectra of the insulating materials prepared in Examples 1-4 and Comparative Examples 1-5, such as Figures 1-2 As shown in the figure, all samples exhibit broad, diffuse peaks within the 2θ = 10°–40° range, without sharp crystalline peaks, confirming that the material has an amorphous structure, consistent with the chemical properties of PEI and PESU. However, with increasing PESU content, the intensity of the 15°–20° peak gradually increases, especially in the 50–20–50 fraction. This is due to the interaction between the sulfone groups of PESU and PEI-F2–N. 0.05 The fluorine / nitro groups form dipole interactions, enhancing the local alignment of the molecular chains. Furthermore, in the polar gradient interface of the multilayer structure, the outer high-PESU (50%) sulfone groups and the middle PESU fluorine / nitro groups form trans-interfacial dipole chains, inducing electron cloud shifts in the groups and forming an ordered dipole network along the interface direction. This directional alignment forces the molecular chains to maintain a specific orientation, reducing disordered stacking and further deepening the peak intensity of the multilayer structure at 15°-20°. The peak changes in XRD indicate that PEI-F2-N... 0.05 Successful construction of the / x%PESU multi-layer structure.

[0095] (2) Infrared spectra of the insulating materials prepared in Examples 1-4 and Comparative Examples 1-5, as shown in the figure. Figures 3-4 As shown in the figure. From the figure, it can be seen that PEI-F2-N 0.05 The peak values ​​of the C=O asymmetric stretching vibration and symmetric stretching vibration are located at 1770-1780 cm⁻¹. -1 1720-1730cm -1 The CF key is located at 1250-1150cm. -1 The stretching vibration peak of the ether bond is at 1240-1250 cm⁻¹. -1 At this point, the C=C skeletal vibration peak of the benzene ring is located at 1600-1450 cm⁻¹. -1 The stretching vibration peak of the CH bond is at 2960-2870 cm⁻¹. -1 Location. Between 1520-1350cm -1The peaks reflect both strong asymmetric and symmetric stretching vibrations of the NO bond in the nitro group of 4N-OP. The asymmetric stretching vibration peak of the sulfone group in PESU is located at 1300 cm⁻¹ in the infrared spectrum. -1 The peak of the symmetrical stretching vibration is at 1150 cm⁻¹. -1 At a location between 830-700cm -1 The peak at 1300-1150 cm⁻¹ is generated by the CH vibration of the aromatic ring on PESU. In summary, the peak at 1300-1150 cm⁻¹ is... -1 The characteristic peak at the location increases with the increase of the proportion of PESU, which is attributed to the increase of the total content of PESU in the multilayer structure.

[0096] (3) Leakage current density diagrams of the insulating materials prepared in Examples 1-4 and Comparative Examples 1-5 at 150°C, as shown in the figure. Figures 5-6 As shown in the figure, compared with single-layer insulation materials, the leakage current density of some multilayer composite insulation materials is further reduced. However, overall, they all show a non-linear trend of first decreasing and then increasing. And when it is PEI-F2-N... 0.05 / 10%PESU and PEI-F2-N 0.05 The leakage current density is lowest when the multilayer composite insulating material contains 20% PESU. This is because interlayer interfaces create interface traps that inhibit electron migration, and the difference in interface barrier height between the middle layer and the two side layers effectively blocks carrier migration across the interface. When the PESU mass fraction is high, interface defects and electric field distortions occur at the interface, causing a surge in leakage current.

[0097] (4) Breakdown diagrams of the insulating materials prepared in Examples 1-4 and Comparative Examples 1-5 at 150°C, as shown. Figures 7-8 As shown in the figure. It can be seen from the figure that for PEI-F2-N... 0.05 / 20% PESU is placed in the edge layer at 150°C, while the middle layer uses PEI-F2-N. 0.05 As the percentage of PESU (where x is the mass percentage of PESU in the blend) increases from 10% to 50%, the breakdown electric field strength gradually decreases: the breakdown electric fields for structures 20-10-20, 20, 20-30-20, 20-40-20, and 20-50-20 are 590 MV / m, 550 MV / m, 500 MV / m, 490 MV / m, and 430 MV / m, respectively. When PEI-F2-N 0.05 / 20% PESU is in the middle layer, at 150°C, while the outer layer uses PEI-F2-N. 0.05As the percentage of PESU increases from 10% to 50%, the breakdown field strength gradually decreases: the breakdown field strengths of structures 10-20-10, 20, 30-20-30, 40-20-40, and 50-20-50 are 620MV / m, 550MV / m, 520MV / m, 510MV / m, and 490MV / m, respectively.

[0098] The above description is only a preferred embodiment of the present invention. Given that those skilled in the art can make appropriate changes and modifications to the above embodiments, the present invention is not limited to the specific embodiments described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an all-organic dielectric insulating material, characterized in that, include: (1) Under vacuum, 0-5℃ and inert atmosphere protection, fluorinated diamine, nitro diamine and ODA are dissolved in a dehydrated and deoxygenated polar aprotic solvent and stirred for 15-30 min to obtain a diamine solution; (2) Under vacuum, 0-5℃ and inert atmosphere protection, BPADA powder was added in batches to the diamine solution of (1), and the reaction was stirred for 5-6 h to obtain PAA-F2-N. 0.05 solution solution; (3) At 15-25℃, respectively, FPAAPAA-F2-N of the same mass were subjected to... 0.05 Different masses of PESU were added to the solution and stirred for 10-16 hours to obtain blended solutions with different PESU mass ratios. (4) When the vacuum degree is ≤10 -3 At Pa and room temperature, the blended solution is subjected to stepwise degassing treatment, and then a film is coated by solution casting method. First, the bottom layer is coated, the middle layer is coated immediately after pre-imidization treatment, and finally the top layer is coated. The resulting wet film is subjected to complete thermal imidization treatment to obtain an all-organic dielectric insulating material. The bottom and top layers are blended solutions with the same mass percentage of PESU, and the mass percentage of PESU used to prepare the middle layer blended solution is twice that used to prepare the bottom layer blended solution.

2. The preparation method according to claim 1, characterized in that, (1) The neutral polar aprotic solvent is DMAC.

3. The preparation method according to claim 1, characterized in that, (1) The ratio of the total molar amount of all diamine monomers in the obtained diamine solution to the molar amount of BPADA is 1:1.008-1:

015.

4. The preparation method according to claim 1, characterized in that, (1) The proportion of fluorinated diamine in the total molar amount of all diamine monomers is 1.8-2.2%, the proportion of nitrodiamine in the total molar amount of all diamine monomers is 0.04-0.06%, and the molar ratio of fluorinated diamine to nitrodiamine is 0.09-0.

11.

5. The preparation method according to claim 1, characterized in that, (3) The solid content of the blended solutions with different PESU mass percentages was 18-22 wt%.

6. The preparation method according to claim 1, characterized in that, (4) The conditions for the intermediate coating are: ultra-dry inert atmosphere, relative humidity ≤1%, oxygen content ≤1ppm.

7. The preparation method according to claim 1, characterized in that, (4) The thickness of the wet film is 4-9 μm, and the thickness of the bottom layer, the middle layer and the top layer are the same.

8. The preparation method according to claim 1, characterized in that, (4) The pre-iminoization process is as follows: heat to 80℃ at 1℃ / min and hold for 5.5-6.5h, then heat to 100℃ at 2℃ / min and hold for 0.8-1.2h; the complete thermal iminoization process is as follows: heat to 80℃ at 1℃ / min and hold for 5.5-6.5h, then heat to 100℃ at 2℃ / min and hold for 0.8-1.2h, then heat to 150℃ at 3℃ / min and hold for 0.8-1.2h, then heat to 200℃ at 5℃ / min and hold for 0.8-1.2h, and finally heat to 275±2℃ at 8℃ / min and hold for 0.8-1.2h.

9. A fully organic dielectric insulating material prepared by the method according to any one of claims 1 to 8, characterized in that, The insulating material has a three-layer macroscopic concentration gradient and a nanoscale seven-layer energy level gradient structure, and its breakdown field strength at 150℃ is ≥600MV / m.

10. An application of the all-organic dielectric insulating material according to claim 9, characterized in that, Insulation for high-voltage electrical equipment and new energy vehicles with an operating ambient temperature ≥125℃ and an operating field strength ≥300MV / m.

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