High-temperature-resistant and high-humidity-resistant thin film capacitor and manufacturing method thereof

Abstract

The invention relates to the technical field of capacitors, and discloses a high-temperature-resistant and high-humidity-resistant thin-film capacitor and a manufacturing method of the high-temperature-resistant and high-humidity-resistant thin-film capacitor. The polypropylene film is prepared from polypropylene, glycidyl methacrylate grafted polyethylene, a high-temperature-resistant modified material, hydrophobic resin, an inorganic filler, a lubricant, a stabilizer and an antioxidant as raw materials; wherein the structure of the high-temperature-resistant modified material contains a large number of silicon-oxygen bonds and rigid benzimidazole structures, the high-temperature-resistant performance of the polypropylene film can be effectively improved, and the structure of the hydrophobic resin contains a large number of C-F bonds, high-hydrophobicity tert-butyl chain links and hydrophobic long alkyl chains, so that the prepared polypropylene film has a good waterproof effect; the service life of the thin-film capacitor is effectively prolonged, and the application effect of the thin-film capacitor in various fields is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to a high-temperature and high-humidity resistant film capacitor and a manufacturing method thereof. Background Art

[0002] Film capacitors use metal foil as electrodes, overlapping them with plastic films such as polypropylene, polycarbonate, or polystyrene at both ends and then winding them into a cylindrical structure. They have advantages such as low polarity, high insulation impedance, and wide frequency response. They are widely used in communications, electronics, home appliances, automobiles, medical equipment, aerospace, and other fields. Among all plastic film capacitors, polypropylene (PP) capacitors have the most significant characteristics. They have excellent electrical properties, including low dielectric constant, low dielectric loss, and high insulation resistance. These characteristics make polypropylene one of the ideal materials for manufacturing film capacitors.

[0003] With the development of power electronics technology, the use of film capacitors is becoming more and more extensive. However, due to the expansion of application areas and the continuous changes in application conditions, the requirements for film capacitor products are also constantly increasing. For example, in new energy vehicles, industrial automation and solar photovoltaic power generation systems, general film capacitors cannot meet the requirements of long-term use under high temperature (85-105°C) and high humidity (90%RH) conditions. When film capacitors are used under high frequency or high pulse conditions, the pulse current passing through the capacitor will cause the capacitor itself to heat up and heat up. When the temperature exceeds the temperature allowed for normal operation of the capacitor, it is easy to cause changes in the insulating medium and damage the capacitor. In addition, if it is in a high humidity environment for a long time, moisture may penetrate into the interior of the film capacitor, causing the electrical properties of the capacitor to change, and the capacity attenuation rate of the capacitor to increase significantly, thereby affecting the stability and service life of the capacitor. Therefore, polypropylene film, as a key material for capacitors, needs to have excellent high temperature resistance and waterproof properties to ensure that the capacitor can work normally in a high temperature and high humidity environment.

[0004] Patent publication number CN115322478B discloses an ultra-thin, high-temperature-resistant polypropylene capacitor film and its manufacturing method. This invention improves the processing performance and temperature resistance of the polypropylene capacitor film by selecting a highly isotactic polypropylene resin and a polypropylene multiphase copolymer through cryogenic grinding and compounding. A β-nucleating agent promotes the formation of a large number of β crystals, improving the impact strength and heat deformation temperature of polypropylene. Therefore, by designing the formulation of the polypropylene film, a high-performance film capacitor can be prepared. Summary of the Invention

[0005] The purpose of the present invention is to provide a high temperature and high humidity resistant film capacitor and a manufacturing method thereof, which solves the following technical problems: (1) Solved the problem of poor high temperature resistance of polypropylene film; (2) The problem of poor waterproofness of polypropylene film was solved.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for manufacturing a high-temperature and high-humidity resistant film capacitor comprises the following manufacturing steps: Step 1: Winding The core is made of polypropylene film, capacitor paper and metal aluminum foil which are stacked and wound in sequence. Step 2: Cold Pressing Cold pressing the core obtained in step 1 at a pressure of 30-35 kg / cm2; Step 3: Hot pressing Fix the cold-pressed core in step 2 with a fixture, place it in an oven, maintain it at 55-65°C for 1-3 hours, then heat it to 75-85°C and keep it for 2-4 hours, continue to heat it to 105-115°C and keep it for 3-5 hours, then heat it to 110-120°C and keep it for 0.5-1.5 hours, and finally cool it to 45-55°C and take it out of the oven to obtain a hot-pressed core; Step 4: Spray gold Spray gold paint on the end surface of the core after hot pressing, with a thickness of 0.5mm to 0.7mm, and tear off the outer tape of the core after the gold spraying is completed; Step 5: Empowerment and Semi-inspection By applying 1.5 to 1.7 times the rated voltage within 7 to 9 seconds, the core processed in step 4 is energized, and its capacity value and loss tangent value are tested to determine whether it meets the design requirements; Step 6: Post-process Then welding, assembly, potting, curing, wire trimming and needle calibration, marking, appearance inspection, packaging and storage are carried out to obtain high temperature and high humidity resistant film capacitors; The polypropylene film comprises the following raw materials in parts by weight: 55-65 parts of polypropylene, 15-25 parts of glycidyl methacrylate grafted polyethylene, 4-10 parts of high-temperature resistant modified material, 3-6 parts of hydrophobic resin, 8-12 parts of inorganic filler, 1-3 parts of lubricant, 2-4 parts of stabilizer, and 0.5-1.5 parts of antioxidant.

[0007] Furthermore, the preparation method of the polypropylene film comprises the following steps: (1) Add polypropylene, glycidyl methacrylate grafted polyethylene, high temperature resistant modified material, and hydrophobic resin into a high-speed mixer, set the speed of the high-speed mixer to 400-600 r / min, stir for 25-35 minutes, add inorganic filler, lubricant, stabilizer, and antioxidant, and continue stirring and mixing for 30-50 minutes to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 220 to 260° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 35-45°C, and the water temperature of the water tank is controlled at 35-45°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 30 to 40°C for 2 to 4 days to obtain a polypropylene film.

[0008] Furthermore, in step (1), the inorganic filler is either calcium carbonate or talc; the lubricant is either paraffin wax or polyethylene wax; the stabilizer is either calcium zinc stabilizer or barium zinc stabilizer; and the antioxidant is either antioxidant 1010, antioxidant 1076 or antioxidant 168.

[0009] Furthermore, the preparation method of the high temperature resistant modified material comprises the following steps: A1: Under argon protection, polybenzimidazole is dissolved in dimethyl sulfoxide, an alkali metal hydride is added, and the mixture is stirred at room temperature for 12 to 36 hours. 2-chloroacrylic acid is then added, and the system temperature is raised to 60 to 80°C, and the mixture is stirred for 12 to 36 hours. After cooling to room temperature, the product is poured into deionized water, filtered, washed, and dried to obtain a modified polybenzimidazole. A2: Add modified polybenzimidazole and N,N-dimethylacetamide to the reactor, ultrasonically disperse for 20 to 40 minutes, pass nitrogen, expel the air, add 1,1,3,3-tetramethyldisiloxane, stir for 10 to 30 minutes, increase the temperature of the system to 70 to 90°C, continue to add platinum catalyst, stir for 4 to 6 hours after addition, wait for the material to cool naturally, filter out the solid material, wash the solid material, and vacuum dry to obtain a high-temperature resistant modified material.

[0010] Furthermore, in step A1, the weight average molecular weight of the polybenzimidazole is 1000 to 5000.

[0011] Furthermore, in step A1, the alkali metal hydride is any one of sodium hydride, lithium hydride or potassium hydride.

[0012] Furthermore, in step A2, the platinum catalyst is a Custer catalyst, and the amount of Custer catalyst added is 0.1 to 0.3% of the total amount of modified polybenzimidazole and 1,1,3,3-tetramethyldisiloxane.

[0013] Through the above technical solution, the NH-bonded hydrogen on the imidazole ring on the polybenzimidazole main chain is deprotonated with an alkali metal hydride, and then reacts with 2-chloroacrylic acid to obtain a modified polybenzimidazole. Under the catalytic action of a platinum catalyst, the unsaturated alkenyl functional group in the modified polybenzimidazole structure undergoes a hydrosilylation reaction with the Si-H in the 1,1,3,3-tetramethyldisiloxane structure, thereby grafting 1,1,3,3-tetramethyldisiloxane into the structure of the polybenzimidazole to obtain a high-temperature resistant modified material.

[0014] Furthermore, the preparation method of the hydrophobic resin comprises the following steps: I: Fluorocarbon resin and toluene are added to a reactor filled with nitrogen in sequence, stirred evenly, and then tert-butyl glycidyl ether and catalyst A are added. The temperature is raised to 75-85°C, and the mixture is stirred at this temperature for 3-5 hours. The solvent is removed by rotary evaporation, and the intermediate material is obtained. II: Add the intermediate material to the butyl acetate solution, mechanically stir and mix, pass nitrogen, expel the air, then add palmitic acid and p-toluenesulfonic acid into the system, raise the system temperature to 105-115°C under stirring conditions, keep warm for 3-5 hours, cool and discharge the material to obtain a hydrophobic resin.

[0015] Furthermore, in step I, the catalyst A is any one of boron trifluoride etherate or tetramethylammonium bromide.

[0016] Through the above technical solution, the active groups in the fluorocarbon resin structure can undergo a ring-opening reaction with the epoxy groups in the tert-butyl glycidyl ether structure under the action of catalyst A to obtain an intermediate material. At the same time, the hydroxyl groups in its structure generated by the ring-opening reaction can react with the carboxyl groups in the palmitic acid structure under the action of p-toluenesulfonic acid, thereby grafting the palmitic acid into the structure of the fluorocarbon resin to obtain a hydrophobic resin.

[0017] A high-temperature and high-humidity resistant film capacitor is manufactured using the above manufacturing method.

[0018] Beneficial effects of the present invention: (1) The high-temperature resistant modified material prepared by the present invention contains a large amount of silicon-oxygen bonds and rigid benzimidazole structures, which can significantly enhance the high-temperature resistance of polypropylene film. Applying it to film capacitors can effectively improve the high-temperature resistance of film capacitors and avoid damage to the capacitors due to high temperature. At the same time, the multiple active carboxyl groups in the high-temperature resistant modified material structure can provide cross-linking sites, so that the high-temperature resistant modified material can produce a cross-linking reaction with the matrix, and the silicon-oxygen bonds and rigid benzimidazole structures can be introduced into the polypropylene main chain to improve the stability of the polypropylene molecular chain, further improving the high-temperature resistance of the polypropylene film, so that the prepared film capacitor can continue to work under high temperature conditions, avoiding problems such as an increase in the self-healing point of the capacitor, a decrease in the withstand voltage, and a decrease in the capacitance value due to high temperature. In addition, the high-temperature resistant modified material structure contains abundant silicon-oxygen bonds, which can improve the waterproof performance of the polypropylene film, thereby extending the service life of the film capacitor.

[0019] (2) The present invention prepares a hydrophobic resin as a filler modifier for polypropylene film. Since the structure of the hydrophobic resin contains a large number of CF-strong, highly hydrophobic tert-butyl chains and hydrophobic long alkyl chains, the prepared polypropylene film has a lower surface energy and can form a super-hydrophobic layer on the surface of the polypropylene film to isolate water vapor and make it difficult for moisture to penetrate into the polypropylene film, thereby achieving a good waterproof effect. Therefore, when it is used to prepare film capacitors, it can give the film capacitors excellent high-humidity resistance and can effectively prevent the film capacitors from being in a high-humidity environment for a long time, causing moisture to penetrate into the interior of the film capacitors, resulting in problems such as electrical performance degradation, short circuit or damage of the capacitors, and effectively extending the service life of the film capacitors. The improvement of these characteristics will greatly improve the application effect of film capacitors in various fields.

[0020] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 These are infrared spectrum test graphs of the polybenzimidazole, modified polybenzimidazole, and high-temperature resistant modified material prepared in Example 1 of the present invention.

[0023] Figure 2 This is an infrared spectrum test chart of the intermediate material and hydrophobic resin prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] Example 1: 1. Preparation of high temperature resistant modified material A1: Under argon protection, 10 g of polybenzimidazole with a weight-average molecular weight of 2000 was dissolved in dimethyl sulfoxide, 5 g of sodium hydride was added, and the mixture was stirred at room temperature for 24 h. 2.4 g of 2-chloroacrylic acid was then added. The system temperature was raised to 70°C, stirred for 24 h, and cooled to room temperature. The product was poured into deionized water, filtered, washed, and dried to obtain a modified polybenzimidazole. A2: Add 5g of modified polybenzimidazole and N,N-dimethylacetamide into the reactor, ultrasonically disperse for 30min, pass nitrogen, expel the air, add 1.2g of 1,1,3,3-tetramethyldisiloxane, stir for 20min, raise the temperature of the system to 80℃, and continue to add 0.01g of platinum (0)-1,3-diethenyl-1,1,3,3-tetramethyldisiloxane. After the addition is completed, stir for 5h, wait for the material to cool naturally, filter out the solid material, wash the solid material, and vacuum dry to obtain a high-temperature resistant modified material.

[0026] The infrared characterization of polybenzimidazole, modified polybenzimidazole and high temperature resistant modified materials was carried out using Nicolet Impact 410 Fourier transform infrared spectrometer. The test results are shown in Figure 1 ,Depend on Figure 1 It can be seen that in the infrared spectrum of polybenzimidazole, 3041cm -1 The absorption peak of the carbon-hydrogen bond in the benzene ring appears at 1305 cm -1 The absorption peak of CN bond appears at 3416cm -1 The absorption peak of the NH bond in the imidazole ring appears at 1619 cm -1 The absorption peak of C=N bond appears at 1628cm -1 The absorption peak of C=N bond appears at 1735cm -1 The characteristic absorption peak of the carboxyl group C=O appears at 3069cm -1 The absorption peak of the carbon-hydrogen bond in the carbon-carbon double bond appears at 1315 cm -1 The absorption peak of CN bond appears at 1320cm, the absorption peak of CN bond is enhanced, and the absorption peak of NH bond in imidazole ring disappears; in the infrared spectrum of high temperature resistant modified material, 1320cm -1The absorption peak of CN bond appears at 1600cm -1 The absorption peak of C=N bond appears at 850cm -1 The absorption peak of Si-C bond appears at 1075cm -1 The absorption peak of Si-O bond appears at , and the absorption peak of carbon-hydrogen bond in carbon-carbon double bond disappears.

[0027] 2. Preparation of hydrophobic resin I: 3 g of fluorocarbon resin and toluene were added to a nitrogen-filled reactor in sequence. After stirring evenly, 0.8 g of tert-butyl glycidyl ether and 0.06 g of boron trifluoride ether were added. The temperature was raised to 80°C. The mixture was stirred at this temperature for 4 h. The solvent was removed by rotary evaporation and the intermediate material was obtained. II: Add 5g of the intermediate material to the butyl acetate solution, stir mechanically to mix, pass nitrogen, and expel the air. Then, add 1.4g of palmitic acid and 0.1g of p-toluenesulfonic acid to the system. While stirring, raise the system temperature to 110°C, keep it warm for 4h, cool it down and discharge the material to obtain a hydrophobic resin.

[0028] The intermediate material and hydrophobic resin were characterized by infrared spectroscopy using Nicolet Impact 410. The test results are shown in Figure 2 ,Depend on Figure 2 It can be seen that in the infrared spectrum of the intermediate material, 1238cm -1 The absorption peak of CF bond appears at 1061cm -1 The absorption peak of ether bond COC appears at 3280 cm -1 The absorption peak of hydroxyl group OH appears at 1170cm -1 The absorption peak of CF bond appears at 1032cm -1 The absorption peak of ether bond COC appears at 1755 cm -1 The absorption peak of the ester group C=O appears at the bottom, and the absorption peak of the hydroxyl group disappears.

[0029] 3. Preparation of polypropylene film (1) Add 55g of polypropylene, 15g of glycidyl methacrylate grafted polyethylene, 4g of high-temperature resistant modified material, and 3g of hydrophobic resin into a high-speed mixer, set the speed of the high-speed mixer to 400r / min, stir for 25min, then add 8g of calcium carbonate, 1g of polyethylene wax, 2g of calcium zinc stabilizer, and 0.5g of antioxidant 1076, continue stirring and mixing for 30min to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 220° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 35°C, and the water temperature of the water tank is controlled at 35°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 30°C for 2 days to obtain a polypropylene film.

[0030] Example 2: Preparation of polypropylene film (1) Add 60g of polypropylene, 20g of glycidyl methacrylate grafted polyethylene, 7g of high-temperature resistant modified material, and 5g of hydrophobic resin into a high-speed mixer, set the speed of the high-speed mixer to 500r / min, stir for 30min, then add 10g of calcium carbonate, 2g of polyethylene wax, 3g of calcium zinc stabilizer, and 1g of antioxidant 1076, continue stirring and mixing for 40min to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 240° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 40°C, and the water temperature of the water tank is controlled at 40°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 35°C for 3 days to obtain a polypropylene film.

[0031] The preparation methods of the high temperature resistant modified material and the hydrophobic resin are the same as those in Example 1.

[0032] Example 3: Preparation of polypropylene film (1) Add 65g of polypropylene, 25g of glycidyl methacrylate grafted polyethylene, 10g of high-temperature resistant modified material, and 6g of hydrophobic resin into a high-speed mixer, set the speed of the high-speed mixer to 600r / min, stir for 35min, then add 12g of calcium carbonate, 3g of polyethylene wax, 4g of calcium zinc stabilizer, and 1.5g of antioxidant 1076, continue stirring and mixing for 50min to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 260° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 45°C, and the water temperature of the water tank is controlled at 45°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 40°C for 4 days to obtain a polypropylene film.

[0033] The preparation methods of the high temperature resistant modified material and the hydrophobic resin are the same as those in Example 1.

[0034] Comparative Example 1 Preparation of polypropylene film (1) Add 60g of polypropylene, 20g of glycidyl methacrylate grafted polyethylene, and 7g of high-temperature resistant modified material into a high-speed mixer, set the speed of the high-speed mixer to 500r / min, stir for 30min, then add 10g of calcium carbonate, 2g of polyethylene wax, 3g of calcium zinc stabilizer, and 1g of antioxidant 1076, continue stirring and mixing for 40min to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 240° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 40°C, and the water temperature of the water tank is controlled at 40°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 35°C for 3 days to obtain a polypropylene film.

[0035] The preparation method of the high temperature resistant modified material is the same as that in Example 1.

[0036] Comparative Example 2 Preparation of polypropylene film (1) Add 60g of polypropylene, 20g of glycidyl methacrylate grafted polyethylene, and 5g of hydrophobic resin into a high-speed mixer, set the speed of the high-speed mixer to 500r / min, stir for 30min, then add 10g of calcium carbonate, 2g of polyethylene wax, 3g of calcium zinc stabilizer, and 1g of antioxidant 1076, and continue stirring and mixing for 40min to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 240° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 40°C, and the water temperature of the water tank is controlled at 40°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 35°C for 3 days to obtain a polypropylene film.

[0037] The preparation method of the hydrophobic resin is the same as that in Example 1.

[0038] Comparative Example 3 Preparation of polypropylene film (1) Add 60g of polypropylene and 20g of glycidyl methacrylate grafted polyethylene into a high-speed mixer, set the speed of the high-speed mixer to 500r / min, stir for 30min, then add 10g of calcium carbonate, 2g of polyethylene wax, 3g of calcium zinc stabilizer, and 1g of antioxidant 1076, and continue stirring and mixing for 40min to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 240° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 40°C, and the water temperature of the water tank is controlled at 40°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 35°C for 3 days to obtain a polypropylene film.

[0039] Performance testing The polypropylene films prepared in Examples 1 to 3 of the present invention and Comparative Examples 1 to 3 were made into samples that met the specifications. The samples were tested for Vicat softening temperature according to GB / T 1633-2000 "Thermoplastics - Determination of Vicat Softening Temperature (VST)". The samples were tested for water contact angle using a PZ-200SD contact angle tester. The specific test results are shown in the table below:

[0040] It can be seen from the above table that the samples prepared in Examples 1 to 3 have excellent high temperature resistance and waterproof performance; no hydrophobic resin was added to the sample prepared in Comparative Example 1, and compared with the example, the water contact angle of the sample decreased significantly, and the waterproof performance of the sample was average, but a high temperature modifier was added thereto, so the high temperature resistance of the sample was good; no high temperature resistant modifier was used as a modifier in the sample prepared in Comparative Example 2, and compared with the example, the high temperature resistance of the sample was poor, but a hydrophobic resin was added thereto, so strong waterproof performance was maintained; no high temperature resistant modifier and hydrophobic resin were added to the sample prepared in Comparative Example 3, so the performance of the sample was the worst.

[0041] The polypropylene films prepared in Examples 1 to 3 were used to manufacture high-temperature and high-humidity resistant film capacitors, respectively. The manufacturing method includes the following steps: Step 1: Winding The core is made of polypropylene film, capacitor paper and metal aluminum foil which are stacked and wound in sequence. Step 2: Cold Pressing According to 32Kg / cm 2 The core obtained in step 1 is cold pressed at a pressure value; Step 3: Hot pressing Fix the cold-pressed core in step 2 with a fixture, place it in an oven, keep it at 60°C for 2 hours, then heat it to 80°C and keep it for 3 hours, continue to heat it to 110°C and keep it for 4 hours, then heat it to 115°C and keep it for 1 hour, and finally cool it to 50°C and take it out of the oven to obtain a hot-pressed core; Step 4: Spray gold After hot pressing, the core end face is sprayed with gold paint to a thickness of 0.6 mm, and the outer tape of the core is torn off after the gold spraying is completed; Step 5: Empowerment and Semi-inspection By applying 1.6 times the rated voltage within 8 seconds, the core processed in step 4 is energized, and its capacitance value and loss tangent value are tested to determine whether it meets the design requirements; Step 6: Post-process Then welding, assembly, potting, curing, wire cutting and needle calibration, marking, appearance inspection, packaging and warehousing are carried out to obtain high temperature and high humidity resistant film capacitors.

[0042] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing a high temperature and high humidity resistant film capacitor, characterized in that: The manufacturing steps include: Step 1: Winding The core is made of polypropylene film, capacitor paper and metal aluminum foil which are stacked and wound in sequence. Step 2: Cold Pressing According to 30~35Kg / cm 2 The core obtained in step 1 is cold pressed at a pressure value; Step 3: Hot pressing Fix the cold-pressed core in step 2 with a fixture, place it in an oven, maintain it at 55-65°C for 1-3 hours, then heat it to 75-85°C and keep it for 2-4 hours, continue to heat it to 105-115°C and keep it for 3-5 hours, then heat it to 110-120°C and keep it for 0.5-1.5 hours, and finally cool it to 45-55°C and take it out of the oven to obtain a hot-pressed core; Step 4: Spray gold Spray gold paint on the end surface of the core after hot pressing, with a thickness of 0.5mm to 0.7mm, and tear off the outer tape of the core after the gold spraying is completed; Step 5: Empowerment and Semi-inspection By applying 1.5 to 1.7 times the rated voltage within 7 to 9 seconds, the core processed in step 4 is energized, and its capacity value and loss tangent value are tested to determine whether it meets the design requirements; Step 6: Post-process Then welding, assembly, potting, curing, wire trimming and needle calibration, marking, appearance inspection, packaging and storage are carried out to obtain high temperature and high humidity resistant film capacitors; The polypropylene film comprises the following raw materials in parts by weight: 55-65 parts of polypropylene, 15-25 parts of glycidyl methacrylate grafted polyethylene, 4-10 parts of high-temperature resistant modified material, 3-6 parts of hydrophobic resin, 8-12 parts of inorganic filler, 1-3 parts of lubricant, 2-4 parts of stabilizer, and 0.5-1.5 parts of antioxidant.

2. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 1, characterized in that: The preparation method of the polypropylene film comprises the following steps: (1) Add polypropylene, glycidyl methacrylate grafted polyethylene, high temperature resistant modified material, and hydrophobic resin into a high-speed mixer, set the speed of the high-speed mixer to 400-600 r / min, stir for 25-35 minutes, add inorganic filler, lubricant, stabilizer, and antioxidant, and continue stirring and mixing for 30-50 minutes to obtain a mixture; (2) placing the mixture obtained in step (1) in a twin-screw extruder, melting it at a temperature of 220 to 260° C., and then extruding the melt into a sheet through the extruder; (3) Cooling the sheet melt prepared in step (2) into a thick sheet through a chill roller and a water tank, wherein the water temperature of the chill roller is controlled at 35-45°C, and the water temperature of the water tank is controlled at 35-45°C; (4) The thick sheet is sequentially subjected to longitudinal stretching, transverse stretching, roughened surface corona treatment, and winding, and then allowed to stand at a temperature of 30 to 40°C for 2 to 4 days to obtain a polypropylene film.

3. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 2, characterized in that: In step (1), the inorganic filler is either calcium carbonate or talc; the lubricant is either paraffin wax or polyethylene wax; the stabilizer is either calcium zinc stabilizer or barium zinc stabilizer; and the antioxidant is either antioxidant 1010, antioxidant 1076 or antioxidant 168.

4. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 1, wherein: The preparation method of the high temperature resistant modified material comprises the following steps: A1: Under argon protection, polybenzimidazole is dissolved in dimethyl sulfoxide, an alkali metal hydride is added, and the mixture is stirred at room temperature for 12 to 36 hours. 2-chloroacrylic acid is then added, and the system temperature is raised to 60 to 80°C, and the mixture is stirred for 12 to 36 hours. After cooling to room temperature, the product is poured into deionized water, filtered, washed, and dried to obtain a modified polybenzimidazole. A2: Add modified polybenzimidazole and N,N-dimethylacetamide to the reactor, ultrasonically disperse for 20 to 40 minutes, pass nitrogen, expel the air, add 1,1,3,3-tetramethyldisiloxane, stir for 10 to 30 minutes, increase the temperature of the system to 70 to 90°C, continue to add platinum catalyst, stir for 4 to 6 hours after addition, wait for the material to cool naturally, filter out the solid material, wash the solid material, and vacuum dry to obtain a high-temperature resistant modified material.

5. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 4, characterized in that: In step A1, the weight average molecular weight of the polybenzimidazole is 1000 to 5000.

6. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 4, characterized in that: In step A1, the alkali metal hydride is any one of sodium hydride, lithium hydride or potassium hydride.

7. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 4, characterized in that: In step A2, the platinum catalyst is a Custer catalyst, and the amount of Custer catalyst added is 0.1 to 0.3% of the total amount of modified polybenzimidazole and 1,1,3,3-tetramethyldisiloxane.

8. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 1, characterized in that: The preparation method of the hydrophobic resin comprises the following steps: I: Fluorocarbon resin and toluene are added to a reactor filled with nitrogen in sequence, stirred evenly, and then tert-butyl glycidyl ether and catalyst A are added. The temperature is raised to 75-85°C, and the mixture is stirred at this temperature for 3-5 hours. The solvent is removed by rotary evaporation, and the intermediate material is obtained. II: Add the intermediate material to the butyl acetate solution, mechanically stir and mix, pass nitrogen, expel the air, then add palmitic acid and p-toluenesulfonic acid into the system, raise the system temperature to 105-115°C under stirring conditions, keep warm for 3-5 hours, cool and discharge the material to obtain a hydrophobic resin.

9. The method for manufacturing a high temperature and high humidity resistant film capacitor according to claim 8, characterized in that: In step I, the catalyst A is either boron trifluoride etherate or tetramethylammonium bromide.

10. A high temperature and high humidity resistant film capacitor, characterized in that: The method according to claim 1 is used for manufacturing.

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