Composite insulating material and preparation method and application thereof

Abstract

The application relates to a composite insulating material and a preparation method and application thereof. The composite insulating material comprises a first polyether sulfone resin layer, an aramid fiber paper layer, a first polyurethane adhesive layer, a mica paper layer, a second polyurethane adhesive layer, an alkali-free glass cloth layer and a second polyether sulfone resin layer which are sequentially stacked, and the mica paper layer is formed by calcined mica paper impregnated with polyurethane adhesive. The composite insulating material has superior comprehensive performance, can meet the use requirements of a new type of driving motor, has better use stability compared with a new type of mica aramid fiber mixed paper and has lower production cost.

Description

Technical Field

[0001] This invention specifically relates to a composite insulating material, its preparation method, and its application. Background Technology

[0002] With the development of electric vehicles, the high power density of electric vehicle drive motors requires, on the one hand, an increase in the voltage level used by electric vehicle motors from the current 150-400V to 800V to reduce ohmic losses and shorten battery charging time; on the other hand, the application of oil cooling technology to reduce motor temperature rise is gradually being promoted and applied in the design of new energy electric vehicle motors. The increase in voltage exacerbates the dielectric loss and heat generated by corona corrosion of insulation materials / insulation systems, accelerating the electrothermal aging of insulation materials / insulation systems. The use of oil cooling technology, however, places demands on oil-resistant insulation materials.

[0003] Currently, the slot insulation, slot cover insulation, and phase insulation for electric vehicle drive motors are still commonly made of a three-layer flexible composite material consisting of two layers of polyaramid fiber paper and one layer of polyimide film bonded together with a high-temperature resistant adhesive. Some oil-cooled drive motors use aramid fiber paper prepared using high-temperature reverse osmosis calendering technology solely as the slot insulation, slot cover insulation, and phase insulation material. This product has ATF oil resistance and heat resistance, but its price is relatively high. In recent years, mica-blended polyaramid fiber paper has become a new application hotspot. Flexible composite materials prepared using mica-containing polyaramid fiber paper and polyimide film have good corona resistance and partial discharge characteristics, which is beneficial for strengthening the insulation performance of 800V drive motors. However, the current product cost is relatively high, and the processability still needs further optimization. Currently, insulation material companies are increasing their R&D efforts to research new flexible composite material alternatives to further reduce costs while meeting the requirements of new drive motors. Summary of the Invention

[0004] The purpose of this invention is to provide a composite insulating material that is lower in cost and has better stability, and is resistant to oil and corona discharge.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A composite insulating material comprises a first polyethersulfone resin layer, an aramid fiber paper layer, a first polyurethane adhesive layer, a mica paper layer, a second polyurethane adhesive layer, an alkali-free glass cloth layer, and a second polyethersulfone resin layer stacked sequentially, wherein the mica paper layer is formed from calcined mica paper impregnated with polyurethane adhesive.

[0007] Preferably, the basis weight of the first polyethersulfone resin layer and the second polyethersulfone resin layer is 5-15 g / m². 2 .

[0008] According to some specific embodiments, the polyethersulfone resin layer is formed from commercially available polyethersulfone resin, more preferably BASF Ultrason E2010 PES resin.

[0009] Preferably, the aramid fiber paper used in the aramid fiber paper layer has a thickness of 38–130 μm and a basis weight of 21–130 g / m². 2 The electrical strength in air at 23℃±2℃ is ≥7.0kV / mm.

[0010] More preferably, the aramid fiber paper used in the aramid fiber paper layer has a thickness of 80–130 μm.

[0011] According to some specific embodiments, the aramid fiber paper is commercially available Yantai Minshida YT510.

[0012] Preferably, the first polyurethane adhesive layer and the second polyurethane adhesive layer are respectively formed of H-grade polyurethane adhesive.

[0013] The H-grade polyurethane adhesive is a commercially available two-component H-grade polyurethane adhesive specifically designed for use in the field of flexible composite materials.

[0014] H-grade polyurethane adhesives with ethyl acetate as the preferred solvent are preferred.

[0015] Preferably, the calcined mica paper has a thickness of 45–105 μm and a basis weight of 50–160 g / m². 2 The electrical strength in air at 23℃±2℃ is 25~35kV / mm.

[0016] More preferably, the thickness of the calcined mica paper is 40–80 μm.

[0017] And / or, the content of polyurethane adhesive on the calcined mica paper is 15-35 g / m³. 2 .

[0018] Preferably, the alkali-free glass cloth used in the alkali-free glass cloth layer has a basis weight of 17.5–27 g / m². 2 .

[0019] Preferably, the alkali-free glass cloth layer is E-glass fiber cloth that meets the JC / T 170-2012 standard.

[0020] According to some specific implementation methods, the alkali-free glass cloth was purchased from Tongcheng Tongli Glass Fiber Co., Ltd.

[0021] Preferably, the thickness of the aramid fiber paper layer is 80–200 μm.

[0022] More preferably, the thickness of the aramid fiber paper layer is 100–200 μm.

[0023] Preferably, the thickness of the calcined mica paper is 45–80 μm.

[0024] Preferably, the thickness of the composite insulating material is 0.2 to 0.5 mm, its high-frequency pulse resistance test life is ≥50 hours, and its PVDI value is greater than 1300V.

[0025] In this invention, the conditions for measuring the high-frequency pulse resistance characteristics are: square wave waveform, temperature 155℃, frequency 20kHz, pulse time 100ns, and voltage 3000V.

[0026] In this invention, the test conditions for PDIV value are as follows: the PD BaseII tester is used to detect the value under power frequency conditions, where the background interference is 5 pc.

[0027] This invention also provides a method for preparing the composite insulating material, the method comprising the following steps:

[0028] (1) A polyethersulfone resin solution is coated on one side surface of aramid fiber paper and dried to form the first polyethersulfone resin layer;

[0029] (2) Coat one side of the mica paper with polyurethane adhesive, partially impregnate the mica paper with polyurethane adhesive, bond one side of the alkali-free glass cloth to the side of the mica paper coated with polyurethane adhesive, and dry to form the second polyurethane adhesive layer between the mica paper and the alkali-free glass cloth.

[0030] (3) Coating a polyethersulfone resin solution onto the surface of the alkali-free glass cloth away from the mica paper, and drying it to form the second polyethersulfone resin layer.

[0031] (4) Coating polyurethane adhesive on the surface of the aramid fiber paper away from the first polyethersulfone resin layer, and drying it to form the first polyurethane adhesive layer.

[0032] (5) The surface of the mica paper away from the alkali-free glass cloth is bonded to the first polyurethane adhesive layer, and then the composite insulating material is formed by pressing, winding and curing.

[0033] Preferably, the polyethersulfone resin solution in steps (1) and (3) is a mixture of polyethersulfone resin and an organic solvent, wherein the organic solvent is one or a mixture of dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone, and the solid content of the polyethersulfone resin solution is 20% to 45%.

[0034] Preferably, the polyurethane adhesive in steps (2) and (4) is a two-component H-grade polyurethane adhesive, and the solvent used in the polyurethane adhesive is ethyl acetate.

[0035] Preferably, the drying temperature in step (1) is 60℃~150℃.

[0036] Preferably, the drying temperature in step (2) is 60℃~120℃.

[0037] Preferably, the drying temperature in step (3) is 80℃~150℃.

[0038] Preferably, the drying temperature in step (4) is 60℃~150℃.

[0039] Preferably, the curing temperature in step (5) is 60℃~80℃.

[0040] Preferably, the curing time in step (5) is 40h to 60h.

[0041] Preferably, in step (2), before drying, a layer of polyurethane adhesive is applied to the surface of the alkali-free glass cloth on the side away from the second polyurethane adhesive layer to improve the adhesion between the glass cloth and the mica paper.

[0042] According to some specific embodiments, the preparation method of the composite insulating material includes the following specific steps:

[0043] S1. Preparation of polyurethane adhesive: Add the two-component H-grade polyurethane adhesive to ethyl acetate solvent according to a fixed ratio, mix evenly, and set aside for use;

[0044] To prepare a polyethersulfone resin solution, polyethersulfone resin (PES resin) is added to one or more of the following solvents in a certain percentage: dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP). The solid content of the PES resin is 20% to 45%. The mixture is then thoroughly mixed and set aside for use.

[0045] S2. PES resin coating treatment on one side of aramid fiber paper: Unwind the aramid paper and coat one side of the aramid paper with a PES resin layer by roller coating. After drying in an oven at 60℃~150℃, rewind for later use.

[0046] S3. Calcined mica paper is unwound. Polyurethane adhesive is coated on one side of the calcined mica paper using a roller coating method. Part of the polyurethane adhesive is impregnated into the mica paper and saturates it. Then, alkali-free glass cloth is unwound. The side of the mica paper coated with urethane adhesive is bonded to the side of the alkali-free glass cloth. Before entering the oven, another layer of polyurethane adhesive is coated on the other side of the alkali-free glass cloth using a roller coating method. The alkali-free glass cloth / calcined mica paper are then placed together in the first oven at a temperature of 60℃~120℃ to remove the ethyl acetate solvent from the polyurethane adhesive and to allow the polyurethane adhesive to be initially cured, thus bonding the alkali-free glass cloth / calcined mica paper together.

[0047] S4. After exiting the first drying oven, PES resin solution is coated on the surface of the alkali-free glass cloth away from the calcined mica paper. Then, it enters the second drying oven at a temperature of 80℃~150℃ to evaporate the organic solvent in the PES resin solution and further cure the polyurethane adhesive on the alkali-free glass cloth / calcined mica paper.

[0048] S5. Unwind the aramid fiber paper coated with PES resin layer on one side in step S1, and coat the other side of the aramid fiber paper with polyurethane adhesive by roller coating. Pass it through another oven at a temperature of 60℃~150℃ to evaporate and remove the solvent in the adhesive layer and allow the adhesive layer to be initially cured.

[0049] S6. After the aramid fiber paper from step S5 exits the drying oven, it is laminated at the pressure roller with the mica paper surface on the side away from the alkali-free glass cloth / calcined mica paper from step S4. After the three layers of alkali-free glass cloth / calcined mica paper / aramid fiber paper are laminated, they are wound up. The wound composite material is placed in a drying room at 60℃~80℃ to continue curing to form a composite insulation material.

[0050] This invention uses a mica paper impregnated with a rich adhesive as a middle layer in a composite material. After the rich adhesive system is cured, it can prevent the mica paper layer from delaminating during application, while fixing the scales in the mica paper to prevent them from falling off, resulting in better stability in use.

[0051] This invention, through its multi-layered composite structure, significantly improves heat resistance and corona resistance while meeting VTM-0 flame retardant requirements (≥180℃), thus satisfying the flame retardant requirements for motor insulation materials. The introduction of the PES resin layer also greatly enhances the AFT oil resistance of the composite material.

[0052] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0053] The composite insulation material of this invention has superior overall performance, which is sufficient to meet the requirements of new drive motors. Compared with the new mica-aramid fiber blended paper, it has better stability and lower production cost. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the structure of the oil-resistant and corona-resistant composite insulating material in the embodiment.

[0055] The components are: 1. First polyethersulfone resin layer; 2. Aramid fiber paper layer; 3. First polyurethane adhesive layer; 4. Mica paper layer; 5. Second polyurethane adhesive layer; 6. Alkali-free glass cloth layer; 7. Second polyethersulfone resin layer. Detailed Implementation

[0056] The technical solution of the present invention is further described below with reference to specific implementation examples, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0057] Unless otherwise specified, all raw materials used in this invention are commercially available products.

[0058] In the following examples and comparative examples, the polyethersulfone resin was BASF Ultrason E2010 PES resin; the aramid fiber paper was purchased from Yantai Minshida Company; the two-component H-grade polyurethane composite adhesive was Henkel two-component polyurethane adhesive; the mica paper was purchased from Hubei Ping An Electrical Materials Co., Ltd.'s MPM2 type calcined mica paper; the alkali-free glass cloth was purchased from Tongcheng Tongli Fiberglass Company; and the polyimide film was purchased from Baoying Jinggong Insulation Materials Co., Ltd.

[0059] The following embodiment provides an oil-resistant and corona-resistant composite insulating material, the structure of which is as follows: Figure 1 As shown, it includes a first polyethersulfone resin layer, an aramid fiber paper layer, a first polyurethane adhesive layer, a mica paper layer, a second polyurethane adhesive layer, an alkali-free glass cloth layer, and a second polyethersulfone resin layer, which are stacked sequentially.

[0060] Example 1

[0061] This embodiment provides an oil-resistant and corona-resistant composite insulating material, which is prepared through the following steps:

[0062] S1. Preparation of polyurethane adhesive: The two-component H-grade polyurethane composite adhesive is added to ethyl acetate solvent according to the fixed ratio provided by the supplier to prepare an adhesive with a certain solid content, and then placed into the glue tank of the composite production line.

[0063] Preparation of polyethersulfone resin solution: Add polyethersulfone resin to a mixed solvent of dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF) in a volume ratio of 1:1 at a certain percentage, and control the solid content of the PES resin solution to 30%.

[0064] S2. A 175μm thick aramid fiber paper is treated with PES coating. After unwinding the aramid fiber paper, a polyethersulfone resin solution is coated onto one side of the aramid fiber paper by roller coating. Then, the organic solvent is evaporated in an oven at 60℃~150℃, thereby forming a coating of approximately 10g / m² on one side of the aramid fiber paper. 2 The first polyethersulfone resin layer.

[0065] S3. 50g / m 2 Calcined mica paper is unwound, and polyurethane adhesive is coated onto one side of the mica paper using a roller coating method. The polyurethane adhesive content on the calcined mica paper is approximately 30 g / m². 2 A portion of the polyurethane adhesive is impregnated into the mica paper, thoroughly soaking it. Simultaneously, a polyurethane adhesive layer forms on the adhesive-coated side of the mica paper. Then, 18g / m³ of adhesive is applied... 2 The alkali-free glass cloth is unwound, and the unwinding position and roller process are used to bond the surface of the mica paper coated with urethane adhesive to the surface of the alkali-free glass cloth. After the mica paper and glass cloth are bonded, before entering the drying oven, a layer of polyurethane adhesive is applied to the other surface of the alkali-free glass cloth by roller coating to improve the adhesion between the alkali-free glass cloth and the mica paper. The alkali-free glass cloth / calcined mica paper enters the first drying oven together. The oven temperature is 60℃~120℃ to remove the ethyl acetate solvent from the polyurethane adhesive and to allow the polyurethane adhesive to initially cure, thus bonding the alkali-free glass cloth / calcined mica paper together.

[0066] S4. After exiting the first drying oven, coat the surface of the alkali-free glass cloth (away from the calcined mica paper) with a PES resin solution, then place it in the second drying oven at 80℃~150℃ to evaporate the organic solvent in the PES resin solution, forming approximately 10g / m² on the other side of the alkali-free glass cloth. 2 The second polyethersulfone resin layer further cures the polyurethane adhesive on the alkali-free glass cloth / calcined mica paper.

[0067] S5. At the winding point, polyurethane adhesive is applied to the other side of the aramid fiber paper by roller coating. The paper is then passed through another oven at a temperature of 60℃~150℃ to evaporate and remove the solvent in the adhesive layer and allow the adhesive layer to initially cure.

[0068] S6. At the pressure roller, the three layers of alkali-free glass cloth / calcined mica paper / aramid fiber paper are laminated and then wound up. The wound composite material is placed in a drying room at 60℃~80℃ for 48 hours to continue curing, thus completing the production of oil-resistant and corona-resistant composite insulation material.

[0069] Example 2

[0070] This embodiment provides an oil-resistant and corona-resistant composite insulating material, which is prepared through the following steps:

[0071] S1. Preparation of polyurethane adhesive: The two-component H-grade polyurethane composite adhesive is added to ethyl acetate solvent according to the fixed ratio provided by the supplier to prepare an adhesive with a certain solid content, and then placed into the glue tank of the composite production line.

[0072] Preparation of polyethersulfone resin solution: Add polyethersulfone resin to a mixed solvent of dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF) in a volume ratio of 1:1 at a certain percentage, and control the solid content of the PES resin solution to 30%.

[0073] S2. A 150μm thick aramid fiber paper is coated with PES. After unwinding the aramid fiber paper, a polyethersulfone resin solution is coated onto one side of the aramid fiber paper by roller coating. Then, the organic solvent is evaporated in an oven at 60℃~150℃, thereby forming a layer of approximately 10g / m² on one side of the aramid fiber paper. 2 The first polyethersulfone resin layer.

[0074] S3. 80g / m 2 Calcined mica paper is unwound, and polyurethane adhesive is coated onto one side of the mica paper using a roller coating method. The polyurethane adhesive content on the calcined mica paper is approximately 35 g / m². 2 A portion of the polyurethane adhesive is impregnated into the mica paper, thoroughly soaking it. Simultaneously, a polyurethane adhesive layer forms on the adhesive-coated side of the mica paper. Then, 18g / m³ of adhesive is applied... 2 The alkali-free glass cloth is unwound, and the unwinding position and roller process are used to bond the surface of the mica paper coated with urethane adhesive to the surface of the alkali-free glass cloth. After the mica paper and calcined mica paper are bonded together, before entering the drying oven, a layer of polyurethane adhesive is applied to the other surface of the alkali-free glass cloth by roller coating to improve the adhesion between the alkali-free glass cloth and the mica paper. The alkali-free glass cloth and calcined mica paper are then placed together in the first drying oven at a temperature of 60℃~120℃ to remove the ethyl acetate solvent from the polyurethane adhesive and to allow the polyurethane adhesive to initially cure, thus bonding the alkali-free glass cloth and calcined mica paper together.

[0075] S4. After exiting the first drying oven, coat the surface of the alkali-free glass cloth (away from the calcined mica paper) with a PES resin solution, then place it in the second drying oven at 80℃~150℃ to evaporate the organic solvent in the PES resin solution, forming approximately 10g / m² on the other side of the alkali-free glass cloth. 2 The second polyethersulfone resin layer further cures the polyurethane adhesive on the alkali-free glass cloth / calcined mica paper.

[0076] S5. At the winding point, polyurethane adhesive is applied to the other side of the aramid fiber paper by roller coating. The paper is then passed through another oven at a temperature of 60℃~150℃ to evaporate and remove the solvent in the adhesive layer and allow the adhesive layer to initially cure.

[0077] S6. At the pressure roller, the three layers of alkali-free glass cloth / calcined mica paper / aramid fiber paper are laminated and then wound up. The wound composite material is placed in a drying room at 60℃~80℃ for 48 hours to continue curing, thus completing the production of oil-resistant and corona-resistant composite insulation material.

[0078] Comparative Example 1

[0079] This comparative example provides a composite insulation material (NHN) of a three-layer composite material of aramid fiber paper / polyimide film / aramid fiber paper.

[0080] Preparation of polyurethane adhesive: The two-component H-grade polyurethane composite adhesive is added to ethyl acetate solvent according to the fixed ratio provided by the supplier to prepare an adhesive with a certain solid content, and then put into the glue tank of the composite production line.

[0081] A 0.075mm thick polyimide film is unwound and coated with polyurethane adhesive on both sides of the film by dipping. The film is then placed in an oven at a temperature of 60℃~120℃ to remove the solvent from the polyurethane adhesive and allow it to cure initially. On the other side of the oven, two rolls of 0.08mm thick aramid fiber paper are unwound and laminated with the coated upper and lower surfaces of the polyimide film at the composite roller. The film is then wound up to form a three-layer composite material NHN and placed in an oven at 60℃~80℃ for further curing for 48 hours.

[0082] Comparative Example 2

[0083] This comparative example provides a composite insulation material of a three-layer composite material of aramid fiber paper / mica paper / alkali-free glass cloth.

[0084] Preparation of polyurethane adhesive: The two-component H-grade polyurethane composite adhesive is added to ethyl acetate solvent according to the fixed ratio provided by the supplier to prepare an adhesive with a certain solid content, and then placed into the glue tank of the composite production line.

[0085] 80g / m 2 Calcined mica paper is unwound, and polyurethane adhesive is coated on both sides of the mica paper using a roller coating method. After baking in an oven at 60℃~120℃, a 175μm thick aramid fiber paper and an 18g / m² layer are coated on the other side of the oven. 2 The alkali-free glass cloth is unwound and then laminated with the upper and lower surfaces of the mica paper after it has been coated with adhesive at the composite roller. The composite is then wound up to form a 3-layer composite material and placed in an oven at 60℃~80℃ for 48 hours to continue curing.

[0086] The thickness of the composite insulating material in the above embodiments and comparative examples was controlled to be approximately 0.25 mm, and performance tests were conducted. The results are shown in Table 1.

[0087] Table 1

[0088]

[0089] The corona resistance life test conditions are as follows: the test is conducted on a high-frequency pulse tester with a square wave waveform, a temperature of 155±2℃, a frequency of 20kHz, a pulse time of 100ns, and a voltage of 3000V.

[0090] The ATF oil resistance test method is as follows: The test sample and ATF oil are placed separately in sealed tubes (0.5 wt% water is added to the ATF oil beforehand to ensure uniform emulsification and dispersion). The sample is completely immersed in the ATF oil and subjected to 8 cycles of high and low temperature cycling tests. The temperature cycling scheme is as follows: The temperature is raised from 25℃ to 155℃, held at 155℃ for 40 hours, then directly switched to -45℃, held for 8 hours, and then switched back to 155℃, constituting one cycle. This cycle is repeated for 8 cycles. Finally, the temperature is returned to 25℃ for relevant performance tests. At the start of the experiment, the heating rate from 25℃ to 155℃ is approximately 2℃ / min. During the experiment, the temperature is directly switched between 155℃ and -45℃ using a temperature surge method, with a switching time of 5-10 minutes.

[0091] Table 1 shows that the composite insulation material of the embodiment exhibits significantly better corona resistance, ATF oil resistance, and PDIV value than the comparative example, meeting the technical requirements for motor insulation materials. Furthermore, the composite insulation material of the embodiment demonstrates better processability; no delamination or mica flake shedding occurred during the stator core slotting process. In contrast, under the same operating conditions, the NHN composite material produced from commercially available mica-aramid fiber blended paper from a certain company exhibited mica flake shedding. Moreover, the cost of the composite insulation material of the embodiment is approximately 20% lower than that of commercially available mica-aramid fiber blended paper.

[0092] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A composite insulating material, characterized in that, It comprises, in sequence, a first polyethersulfone resin layer, an aramid fiber paper layer, a first polyurethane adhesive layer, a mica paper layer, a second polyurethane adhesive layer, an alkali-free glass cloth layer, and a second polyethersulfone resin layer. The mica paper layer is formed from calcined mica paper impregnated with polyurethane adhesive. The preparation method of the composite insulating material includes the following steps: (1) A polyethersulfone resin solution is coated on one side surface of aramid fiber paper and dried to form the first polyethersulfone resin layer; (2) Coat one side of the mica paper with polyurethane adhesive, partially impregnate the mica paper with polyurethane adhesive, bond one side of the alkali-free glass cloth to the side of the mica paper coated with polyurethane adhesive, and dry to form the second polyurethane adhesive layer between the mica paper and the alkali-free glass cloth. (3) Coating a polyethersulfone resin solution onto the surface of the alkali-free glass cloth away from the mica paper, and drying it to form the second polyethersulfone resin layer; (4) Coating polyurethane adhesive on the surface of the aramid fiber paper away from the first polyethersulfone resin layer, and drying it to form the first polyurethane adhesive layer. (5) The surface of the mica paper away from the alkali-free glass cloth is bonded to the first polyurethane adhesive layer, and then the composite insulating material is formed by pressing, winding, and curing. The polyethersulfone resin solution in steps (1) and (3) is a mixture of polyethersulfone resin and an organic solvent, wherein the organic solvent is one or a mixture of dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone, and the solid content of the polyethersulfone resin solution is 20% to 45%.

2. The composite insulating material according to claim 1, characterized in that, The basis weight of the first polyethersulfone resin layer and the second polyethersulfone resin layer is 5~15 g / m². 2 ; And / or, the aramid fiber paper layer uses aramid fiber paper with a thickness of 38~130μm and a basis weight of 21~130g / m². 2 The electrical strength in air at 23℃±2℃ is ≥7.0kV / mm; And / or, the first polyurethane adhesive layer and the second polyurethane adhesive layer are respectively formed of H-grade polyurethane adhesive; And / or, the calcined mica paper has a thickness of 45~105μm and a basis weight of 50~160g / m². 2 ; And / or, the content of polyurethane adhesive on the calcined mica paper is 15~35 g / m³. 2 ; And / or, the alkali-free glass cloth used in the alkali-free glass cloth layer has a basis weight of 17.5~27 g / m². 2 .

3. The composite insulating material according to claim 1, characterized in that, The thickness of the aramid fiber paper layer is 80~200μm; And / or, the thickness of the calcined mica paper is 45~80μm.

4. The composite insulating material according to claim 1, characterized in that, The composite insulating material has a thickness of 0.2~0.5mm, a test life of ≥50 hours for its high-frequency pulse resistance characteristics, and a PVDI value greater than 1300V.

5. The composite insulating material according to claim 1, characterized in that, The polyurethane adhesive used in steps (2) and (4) is a two-component H-grade polyurethane adhesive.

6. The composite insulating material according to claim 1, characterized in that, The drying temperatures in step (1) are 60℃~150℃; And / or, the drying temperature in step (2) is 60℃~120℃; And / or, the drying temperature in step (3) is 80℃~150℃; And / or, the drying temperature in step (4) is 60℃~150℃; And / or, the curing temperature in step (5) is 60℃~80℃.

7. The composite insulating material according to claim 1, characterized in that, In step (2), before drying, a layer of polyurethane adhesive is applied to the surface of the alkali-free glass cloth on the side away from the second polyurethane adhesive layer.

8. The application of the composite insulating material as described in any one of claims 1 to 7 in the drive motor of an electric vehicle.

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