High-temperature-resistant, high-voltage-resistant and anti-breakdown capacitor base film and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant, high-voltage-resistant and anti-breakdown capacitor base film and a preparation method thereof. The high-temperature-resistant, high-voltage-resistant and anti-breakdown capacitor base film is prepared from the following raw materials in parts by weight: 100 parts of polypropylene; 17 to 36 parts of polyvinylidene fluoride; 3-12 parts of enhanced and improved talcum powder; 1-6.5 parts of modified barium titanate; 1-6 parts of a cross-linking agent; 2-10 parts of a compatilizer; and 0.05-2 parts of an initiator. The capacitor base film is high in mechanical strength, and has excellent high temperature resistance, thermo-oxidative aging resistance, high voltage resistance and anti-breakdown performance; the enhanced and improved talcum powder is constructed by taking expanded layer modified talc as a carrier and titanium dioxide-carbon dot composite particles as a loading component and grafting and coating the organic matter, so that the defects of the talcum powder can be overcome, and the improvement effect of the talcum powder on heat resistance, high-voltage resistance and breakdown resistance can be fully exerted; meanwhile, the system can be endowed with excellent thermo-oxidative aging resistance.

Description

Technical Field

[0001] The present invention relates to the field of capacitor base films, and particularly to a high-temperature resistant, high-voltage resistant and breakdown-proof capacitor base film and a preparation method thereof. Background Art

[0002] As one of the three major passive components, capacitors are widely used in various electronic products. The capacitor film is the core material of thin-film capacitors.

[0003] Polypropylene (PP) is a commonly used capacitor film base material, which has good comprehensiveness. However, with the increasing requirements of the market for capacitor films, higher requirements are put forward for the high-temperature resistance, heat-oxidation aging resistance, and high-voltage resistance of capacitor films.

[0004] Patent CN118772538B discloses a high-temperature resistant and high-performance polypropylene capacitor base film, which can preferably improve the heat resistance and mechanical strength of the polypropylene capacitor base film, but it does not perform relevant enhancement improvements on the high-voltage resistance performance.

[0005] Patent CN103951880B discloses a breakdown-proof and high-performance metalized film for capacitors and a preparation method thereof, which can effectively improve the breakdown-proof performance of the capacitor film, but does not study the heat-oxidation aging resistance performance.

[0006] Therefore, it is necessary to improve the existing technology to provide a more reliable solution. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a high-temperature resistant, high-voltage resistant and breakdown-proof capacitor base film and a preparation method thereof in view of the above deficiencies in the prior art.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: In the first aspect of the present invention, a high-temperature resistant, high-voltage resistant and breakdown-proof capacitor base film is provided, and the preparation raw materials thereof include, by weight: 100 parts of polypropylene; 17 - 36 parts of polyvinylidene fluoride; 3 - 12 parts of enhanced and improved talcum powder; 1 - 6.5 parts of modified barium titanate; 1 - 6 parts of cross-linking agent; 2 - 10 parts of compatibilizer; 0.05 - 2 parts of initiator; The enhanced and improved talcum powder is prepared by the following method: S1. Expand the layer of talc to obtain expanded and modified talc; S2. Prepare the loaded and modified talc: In-situ synthesize titanium dioxide-carbon dot composite particles on the expanded-layer modified talc to obtain the loaded and modified talc; S3. Perform an organic coating treatment on the loaded and modified talc to obtain the enhanced and improved talc powder.

[0009] Preferably, the enhanced and improved talc powder is prepared by the following method: S1. Calcinate the talc, add it to deionized water after cooling, add 2-carboxyethylphenylphosphinic acid, stir and reflux under heating, centrifuge and filter after standing, vacuum dry the solid product, and grind it to obtain the expanded-layer modified talc; S2. Prepare the loaded and modified talc: S2-1. Add the expanded-layer modified talc and titanium tetrachloride to deionized water, and ultrasonically disperse to obtain mixture 1; S2-2. Take urea, sucrose, lutein, and ethylenediamine, add them to deionized water, and stir to obtain mixture 2; S2-3. Add mixture 2 to mixture 1 under stirring, ultrasonically disperse, then dropwise add an aqueous sodium hydroxide solution, and heat and react to obtain a precursor; S2-4. Transfer the precursor to a reaction kettle, react under heating, cool after the reaction ends, filter, wash the solid product, vacuum dry, and grind to obtain the loaded and modified talc; S3. Take the loaded and modified talc and ethanol, add them to deionized water, ultrasonically disperse, then add sodium dodecyl sulfate, stir, then add acrylic acid, adjust the pH with hydrochloric acid, stir and react under heating, stand, filter, wash the solid product, vacuum dry, and grind to obtain the enhanced and improved talc powder.

[0010] Preferably, step S1 is specifically: Calcinate 0.5 - 2 g of talc at 600 - 750 °C for 3 - 8 h, add it to 50 - 200 mL of deionized water after cooling, add 0.35 - 1.3 g of 2-carboxyethylphenylphosphinic acid, stir and reflux at 60 - 80 °C for 3 - 12 h, centrifuge and filter after standing for 1 - 4 h, vacuum dry the solid product at 70 - 100 °C, and grind it to less than 5 - 20 μm to obtain the expanded-layer modified talc.

[0011] Preferably, step S2 is specifically: S2-1. Take 1 - 42 g of the expanded-layer modified talc and 0.19 - 0.76 g of titanium tetrachloride, add them to 50 - 200 mL of deionized water, and ultrasonically disperse for 15 - 60 min to obtain mixture 1; S2-2. Take 90 - 360 mg of urea, 342 - 1368 mg of sucrose, 142 - 569 mg of lutein, and 60 - 240 mg of ethylenediamine, add them to 25 - 100 mL of deionized water, and stir for 5 - 30 min to obtain mixture 2; S2-3. While stirring, add mixture 2 to mixture 1, ultrasonically disperse for 5 - 20 min, then dropwise add 7.5 - 30 mL of an aqueous sodium hydroxide solution with a concentration of 0.5 - 2 mol / L, and react at 30 - 40 °C for 0.5 - 2 h to obtain a precursor; S2-4. Transfer the precursor to a stainless steel autoclave with a polytetrafluoroethylene liner, react at 160 - 210 °C for 6 - 24 h, after the reaction is completed, cool to room temperature, filter, wash the solid product with deionized water, vacuum dry at 70 - 100 °C for 6 - 24 h, and grind to obtain the loaded modified talc.

[0012] Preferably, step S3 is specifically as follows: Take 1 - 4 g of the loaded modified talc and 50 - 200 mL of ethanol and add them to 125 - 500 mL of deionized water, ultrasonically disperse for 15 - 60 min, then add 3.5 - 14 g of sodium dodecyl sulfate, stir for 5 - 20 min, then add 1.75 - 7 mL of acrylic acid, adjust the pH value to 3 - 5 with hydrochloric acid, stir and react at 70 - 82 °C for 1 - 4 h, let stand for 4 - 16 h, filter, wash the solid product with deionized water, vacuum dry at 50 - 80 °C for 6 - 24 h, grind, and pass through a 5 - 20 μm sieve to obtain the enhanced and improved talc powder.

[0013] Preferably, the enhanced and improved talc powder is prepared by the following method: S1. Perform an intercalation treatment on talc to obtain intercalation - modified talc: Calcine 1 g of talc at 700 °C for 6 h, after cooling, add it to 100 mL of deionized water, add 0.65 g of 2 - carboxyethylphenylphosphinic acid, stir and reflux at 70 °C for 6 h, let stand for 2 h and then centrifuge and filter, vacuum - dry the solid product at 90 °C, and grind it to less than 10 μm to obtain the intercalation - modified talc; S2. Prepare the loaded modified talc: S2-1. Take 2 g of the intercalation - modified talc and 0.38 g of titanium tetrachloride and add them to 100 mL of deionized water, ultrasonically disperse for 30 min to obtain mixture 1; S2-2. Take 180 mg of urea, 684 mg of sucrose, 284.5 mg of lutein, and 120 mg of ethylenediamine and add them to 50 mL of deionized water, stir for 15 min to obtain mixture 2; S2-3. While stirring, add mixture 2 to mixture 1, ultrasonically disperse for 10 min, then dropwise add 15 mL of an aqueous sodium hydroxide solution with a concentration of 1 mol / L, and react at 35 °C for 1 h to obtain a precursor; S2-4. Transfer the precursor to a stainless steel reactor with a polytetrafluoroethylene liner, react at 180 °C for 12 h, cool to room temperature after the reaction, filter, wash the solid product with deionized water, dry it under vacuum at 90 °C for 12 h, and grind it to obtain the supported modified talc; S3. Perform an organic coating treatment on the supported modified talc to obtain the enhanced and improved talc powder: Take 2 g of the supported modified talc and 100 mL of ethanol, add them to 250 mL of deionized water, ultrasonically disperse for 30 min, then add 7 g of sodium dodecyl sulfate, stir for 10 min, then add 3.5 mL of acrylic acid, adjust the pH value to 4.5 with hydrochloric acid, stir and react at 78 °C for 2 h, let it stand for 8 h, filter, wash the solid product with deionized water, dry it under vacuum at 70 °C for 12 h, grind it, and pass through a 10-μm sieve to obtain the enhanced and improved talc powder.

[0014] Preferably, the modified barium titanate is prepared by the following method: 1) Take 0.5 - 2 g of polymethyl methacrylate and 25 - 100 mL of deionized water, add them to 50 - 200 mL of ethanol, and ultrasonically disperse for 15 - 60 min; 2) Take 1 - 4 g of nano-barium titanate, add it to 50 - 200 mL of ethanol, ultrasonically disperse for 15 - 60 min, drop the obtained mixture into the product of step 1), stir for 30 - 90 min, then adjust the pH to 3.0 - 5.0 with 0.02 - 0.2 mol / L nitric acid, stir and react at 30 - 60 °C for 2 - 8 h, filter, wash the solid product with ethanol, dry it under vacuum at 30 - 50 °C for 4 - 12 h to obtain the modified barium titanate.

[0015] Preferably, the modified barium titanate is prepared by the following method: 1) Take 1 g of polymethyl methacrylate and 50 mL of deionized water, add them to 100 mL of ethanol, and ultrasonically disperse for 30 min; 2) Take 2 g of nano-barium titanate, add it to 100 mL of ethanol, ultrasonically disperse for 30 min, drop the obtained mixture into the product of step 1), stir for 45 min, then adjust the pH to 4.0 with 0.05 mol / L nitric acid, stir and react at 45 °C for 4 h, filter, wash the solid product with ethanol, dry it under vacuum at 50 °C for 8 h to obtain the modified barium titanate.

[0016] Preferably, the crosslinking agent is one or two of trimethylolpropane trimethacrylate and pentaerythritol triacrylate, and the compatibilizer is maleic anhydride grafted polypropylene.

[0017] In the second aspect of the present invention, a method for preparing a high-temperature resistant, high-voltage resistant and anti-breakdown capacitor base film as described above is provided, including the following steps: S1. Mix polypropylene, polyvinylidene fluoride, enhanced and improved talc powder, modified barium titanate, and compatibilizer at 40 - 60 °C for 10 - 40 min. Add the obtained mixture to an extruder for melt extrusion, and control the extrusion temperature at 220 °C - 280 °C; S2. Cool the cast film, and the cooling temperature is 50 - 80 °C; S3. Perform biaxial stretching at 150 - 175 °C, with the longitudinal stretching ratio being 2.5 - 5.5 times and the transverse stretching ratio being 2 - 3 times, to obtain a base film with a thickness of 1 - 20 μm; S4. Fluorination treatment: Place the base film in a reaction kettle pre - replaced with nitrogen, and introduce a mixed gas of fluorine and nitrogen into the reaction kettle. React at 40 - 65 °C and a pressure of 0.05 - 0.4 MPa for 30 - 120 min to obtain a high - temperature - resistant, high - voltage - resistant, and anti - breakdown capacitor base film.

[0018] The beneficial effects of the present invention are: The present invention provides a high - temperature - resistant, high - voltage - resistant, and anti - breakdown capacitor base film and its preparation method. The capacitor base film has high mechanical strength, and at the same time has excellent high - temperature resistance, heat - resistant oxygen aging performance, and high - voltage - resistant and anti - breakdown performance; In the present invention, by using expanded - layer modified talc as a carrier, titanium dioxide - carbon dot composite particles as a loaded component, and grafting and coating organic substances to construct enhanced and improved talc powder, the above - mentioned defects of talc powder can be overcome, and its promotion effect on heat - resistant performance and high - voltage - resistant and anti - breakdown performance can be fully exerted. At the same time, it can endow the system with excellent anti - heat - oxygen aging performance.

[0019] In the enhanced and improved talc powder of the present invention, first mix expanded - layer modified talc with titanium tetrachloride, so that titanium ions are connected to the surface and interlayer of the expanded - layer modified talc through the combination with functional groups such as silanol groups, then mix with the raw materials for preparing carbon dots, and generate a precursor under alkaline conditions. Finally, through a hydrothermal reaction, carbon dots doped with titanium dioxide are synthesized. The carbon dots inherit the reducibility of lutein well and show excellent antioxidant performance. The doping of titanium dioxide can accelerate the electron transfer rate, enhance the antioxidant performance of the carbon dots. At the same time, nanoscale titanium dioxide has excellent corona resistance and can further improve the high - voltage - resistant and anti - breakdown performance of the base film.

[0020] In the enhanced and improved talc powder of the present invention, by grafting and coating acrylic acid on the loaded modified talc, enhanced and improved talc powder is obtained. After the enhanced and improved talc powder is added to the polypropylene matrix, under the action of an initiator and high temperature, acrylic acid undergoes a grafting reaction with the polypropylene matrix, so that the enhanced and improved talc powder coated with acrylic acid can be uniformly dispersed in the polypropylene matrix and can increase the interfacial connection strength; at the same time, the grafting of acrylic acid also promotes the improvement of the thermal stability of the polypropylene matrix.

[0021] In the present invention, coating barium titanate with polymethyl methacrylate can improve the compatibility between barium titanate and polypropylene, promote its uniform dispersion, and at the same time, the compounding of polymethyl methacrylate and polypropylene can also improve the weather resistance and strength of the polypropylene-based film. Description of the Drawings

[0022] Figure 1 is the breakdown voltage test results of the examples and comparative examples; Figure 2 is the longitudinal tensile strength test results of the examples and comparative examples; Figure 3 is the transverse tensile strength test results of the examples and comparative examples; Figure 4 is the thermal shrinkage rate test results of the examples and comparative examples; Figure 5 is the heat and oxygen aging resistance test results of the examples and comparative examples; Figure 6 is the antioxidant performance test results of the enhanced and improved talc powder prepared in Example 1, Comparative Example 2 and Comparative Example 3. Detailed Description of the Invention

[0023] The following examples are used to further illustrate the present invention in detail, so that those skilled in the art can implement it according to the description in the specification.

[0024] It should be understood that the terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0025] Unless otherwise specified, the test methods used in the following examples are all conventional methods. The materials and reagents used in the following examples, unless otherwise specified, can all be obtained from commercial sources. For those not specified in the following examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments without indicating the manufacturer, they are all conventional products that can be purchased commercially.

[0026] The present invention provides a high-temperature resistant, high-voltage resistant and breakdown-proof capacitor base film, and its preparation raw materials include, by weight: 100 parts of polypropylene; 17 - 36 parts of polyvinylidene fluoride; 3 - 12 parts of enhanced and improved talc powder; 1 - 6.5 parts of modified barium titanate; 1 - 6 parts of crosslinking agent; 2 - 10 parts of compatibilizer; 0.05 - 2 parts of initiator.

[0027] In the present invention, the enhanced and improved talc powder is prepared by the following method: S1. Expand the layer of talc to obtain expanded and modified talc: Calcine 0.5 - 2 g of talc at 600 - 750 °C for 3 - 8 h. After cooling, add it to 50 - 200 mL of deionized water, add 0.35 - 1.3 g of 2 - carboxyethylphenylphosphinic acid, stir and reflux at 60 - 80 °C for 3 - 12 h, let it stand for 1 - 4 h, then centrifuge and filter. The solid product is vacuum - dried at 70 - 100 °C and ground to less than 5 - 20 μm to obtain expanded and modified talc.

[0028] S2. Prepare loaded and modified talc: In - situ synthesize titanium dioxide - carbon dot composite particles on the expanded and modified talc to obtain loaded and modified talc: S2 - 1. Take 1 - 42 g of expanded and modified talc and 0.19 - 0.76 g of titanium tetrachloride, add them to 50 - 200 mL of deionized water, and ultrasonically disperse for 15 - 60 min to obtain mixture 1; S2 - 2. Take 90 - 360 mg of urea, 342 - 1368 mg of sucrose, 142 - 569 mg of lutein, and 60 - 240 mg of ethylenediamine, add them to 25 - 100 mL of deionized water, and stir for 5 - 30 min to obtain mixture 2; S2 - 3. Under stirring, add mixture 2 to mixture 1, ultrasonically disperse for 5 - 20 min, then dropwise add 7.5 - 30 mL of sodium hydroxide aqueous solution with a concentration of 0.5 - 2 mol / L, and react at 30 - 40 °C for 0.5 - 2 h to obtain a precursor; S2 - 4. Transfer the precursor to a stainless - steel reaction kettle with a polytetrafluoroethylene liner, react at 160 - 210 °C for 6 - 24 h. After the reaction, cool to room temperature, filter, wash the solid product with deionized water, vacuum - dry at 70 - 100 °C for 6 - 24 h, and grind to obtain loaded and modified talc.

[0029] S3. Perform organic coating treatment on the loaded and modified talc to obtain enhanced and improved talc powder: Take 1 - 4 g of loaded and modified talc and 50 - 200 mL of ethanol, add them to 125 - 500 mL of deionized water, ultrasonically disperse for 15 - 60 min, then add 3.5 - 14 g of sodium dodecyl sulfate, stir for 5 - 20 min, then add 1.75 - 7 mL of acrylic acid, adjust the pH value to 3 - 5 with hydrochloric acid, stir and react at 70 - 82 °C for 1 - 4 h, let it stand for 4 - 16 h, filter, wash the solid product with deionized water, vacuum - dry at 50 - 80 °C for 6 - 24 h, grind, and pass through a 5 - 20 μm sieve to obtain enhanced and improved talc powder.

[0030] Talc is a hydrated magnesium silicate mineral with a three-sided three-layer structure. It has excellent high-temperature stability and can improve the high-temperature resistance of the membrane material. At the same time, talc is a non-conductor of electricity and has good electrical insulation properties. Doping in the polypropylene matrix changes the dielectric properties of the film and can improve the high-voltage resistance and anti-breakdown performance of the film. However, the compatibility between talc and the polypropylene system is poor and it is easy to agglomerate, which affects the performance of talc. When the addition amount is too large, it is also easy to deteriorate the mechanical properties of the film. In addition, the polypropylene-based film is more likely to oxidize at high temperatures, resulting in a shortened service life of the base film. In the present invention, by using expanded modified talc as a carrier, titanium dioxide-carbon dot composite particles as a loaded component, and grafting and coating organic substances, an enhanced and improved talc powder is constructed, which can overcome the above defects of talc powder, give full play to its improvement effect on heat resistance and high-voltage resistance and anti-breakdown performance, and at the same time can endow the system with excellent thermal oxidation resistance performance.

[0031] In the present invention, talc is first expanded by high-temperature calcination and treatment with 2-carboxyethylphenylphosphinic acid to increase its layer spacing, which is beneficial to improving its high-temperature resistance and electrical insulation properties, and is also beneficial to the subsequent loading of titanium dioxide-carbon dot composite particles; Then, titanium dioxide-carbon dot composite particles are in-situ synthesized on the expanded modified talc by a one-pot hydrothermal method to obtain loaded modified talc; in this process, the expanded modified talc is first mixed with titanium tetrachloride, so that titanium ions are connected to the surface and interlayer of the expanded modified talc through the combination with functional groups such as silanol groups, and then mixed with the raw materials for preparing carbon dots, and a precursor is generated under alkaline conditions. Finally, through hydrothermal reaction, carbon dots doped with titanium dioxide are synthesized. The carbon dots inherit the reducibility of lutein well and exhibit excellent antioxidant properties. The doping of titanium dioxide can accelerate the electron transfer rate and enhance the antioxidant properties of the carbon dots. At the same time, nanoscale titanium dioxide has excellent corona resistance and can further improve the high-voltage resistance and anti-breakdown performance of the base film.

[0032] Finally, acrylic acid is grafted and coated on the loaded modified talc to obtain an enhanced and improved talc powder. After the enhanced and improved talc powder is added to the polypropylene matrix, under the action of an initiator and high temperature, acrylic acid undergoes a graft reaction with the polypropylene matrix, so that the enhanced and improved talc powder coated with acrylic acid can be uniformly dispersed in the polypropylene matrix and can increase the interfacial connection strength; at the same time, the grafting of acrylic acid also promotes the improvement of the thermal stability of the polypropylene matrix.

[0033] In the present invention, the modified barium titanate is prepared by the following method: 1) Take 0.5 - 2 g of polymethyl methacrylate (PMMA), 25 - 100 mL of deionized water and add them to 50 - 200 mL of ethanol, and ultrasonically disperse for 15 - 60 min; 2) Add 1 - 4 g of nano - barium titanate into 50 - 200 mL of ethanol, ultrasonically disperse for 15 - 60 min, drop the obtained mixture into the product of step 1), stir for 30 - 90 min, then adjust the pH to 3.0 - 5.0 with 0.02 - 0.2 mol / L nitric acid, stir and react at 30 - 60 °C for 2 - 8 h, filter, wash the solid product with ethanol, and vacuum - dry at 30 - 50 °C for 4 - 12 h to obtain modified barium titanate.

[0034] Barium titanate is a very typical perovskite - type structure crystal, with characteristics such as high dielectric constant, low dielectric loss, large resistivity, high breakdown voltage strength, and excellent insulation performance. Its addition can further improve the high - voltage resistance and anti - breakdown performance of the base film; however, there is a problem of poor compatibility between barium titanate and the polypropylene matrix. In the present invention, coating barium titanate with polymethyl methacrylate can improve the compatibility between barium titanate and polypropylene, promote its uniform dispersion, and at the same time, the compounding of polymethyl methacrylate and polypropylene can also improve the weather resistance and strength of the polypropylene base film.

[0035] In a preferred embodiment, the cross - linker is one or two of trimethylolpropane trimethacrylate and pentaerythritol triacrylate.

[0036] In a preferred embodiment, the compatibilizer is maleic anhydride - grafted polypropylene.

[0037] The present invention also provides a method for preparing a high - temperature - resistant, high - voltage - resistant and anti - breakdown capacitor base film as above, including the following steps: S1. Stir - mix polypropylene, polyvinylidene fluoride, reinforcing and improving talcum powder, modified barium titanate, and compatibilizer at 40 - 60 °C for 10 - 40 min, add the obtained mixture into an extruder for melt - extrusion, and control the extrusion temperature at 220 °C - 280 °C; S2. Cool and cast the film, and the cooling temperature is 50 - 80 °C; S3. Perform biaxial stretching at 150 - 175 °C, with the longitudinal stretching ratio being 2.5 - 5.5 times and the transverse stretching ratio being 2 - 3 times to obtain a base film with a thickness of 1 - 20 μm; S4. Fluorination treatment: Place the base film in a reaction kettle pre - replaced with nitrogen, introduce a mixed gas of fluorine and nitrogen into the reaction kettle, and react at 40 - 65 °C and a pressure of 0.05 - 0.4 MPa for 30 - 120 min to obtain a high - temperature - resistant, high - voltage - resistant and anti - breakdown capacitor base film.

[0038] In the present invention, by subjecting the base film to surface fluorination treatment to form a fluorinated layer that can block the entry of charges into the base film (when fluorine gas contacts polyolefin, fluorine atoms will replace the hydrogen atoms in its surface layer to form a fluorinated surface layer, while the bulk properties of the polymer remain unchanged), the high-voltage resistance and breakdown prevention performance of the base film can be somewhat improved. The main mechanism is as follows: Firstly, fluorination increases the surface dielectric constant and reduces the surface electric field strength, thereby reducing the injection of electrode charges; Secondly, fluorination reduces the free volume of the film surface layer, further blocking the entry of charges into the body (Zhuo Miaojin, Wang Xin, An Zhenlian. Influence of Fluorination Temperature on DC Breakdown Performance of Biaxially Oriented Polypropylene Films [J]. Engineering Journal of Wuhan University, 2024, 57(6).).

[0039] The above is the overall concept of the present invention. The following provides detailed examples and comparative examples based on it to further illustrate the present invention.

[0040] Description of the sources of main reagents: Polypropylene resin, brand SK, grade R370Y, purchased from Suzhou Yitianli Plastic Co., Ltd.; Polyvinylidene fluoride, grade PH70300WVWLE, purchased from Suzhou Yitianli Plastic Co., Ltd.; Talc powder, Nanjing Chuhai New Material Technology Co., Ltd.; Nanometer barium titanate, 200 nm, Guangzhou Hongwu Material Technology Co., Ltd.; Polymethyl methacrylate, grade HI513, Shanghai Hehongcheng Plastic Technology Co., Ltd.; Maleic anhydride grafted polypropylene, model QB510, Baiyi New Material Technology (Dongguan) Co., Ltd.; Trimethylolpropane trimethacrylate, Jiangsu Bost Chemical Technology Co., Ltd.

[0041] Example 1 A high-temperature resistant, high-voltage resistant and breakdown-proof capacitor base film, characterized in that its preparation raw materials include, by weight: 100 parts of polypropylene; 25 parts of polyvinylidene fluoride; 9 parts of reinforcing and improving talc powder; 3 parts of modified barium titanate; 1.5 parts of crosslinking agent; 4.5 parts of compatibilizer; 0.15 part of initiator.

[0042] The crosslinking agent is trimethylolpropane trimethacrylate, and the compatibilizer is maleic anhydride grafted polypropylene.

[0043] The preparation method of the capacitor base film includes the following steps: S1. Mix polypropylene, polyvinylidene fluoride, enhanced and improved talc powder, modified barium titanate, and compatibilizer at 50°C for 20 min. Add the obtained mixture to an extruder for melt extrusion, and control the extrusion temperature at 250°C. S2. Cool the cast film, and the cooling temperature is 70°C. S3. Perform biaxial stretching at 160°C, with the longitudinal stretching ratio being 4 times and the transverse stretching ratio being 2.5 times, to obtain a base film with a thickness of 10 μm. S4. Fluorination treatment: Place the base film in a reaction kettle pre-replaced with nitrogen, and introduce a mixed gas composed of fluorine gas and nitrogen in a volume ratio of 1.5:8.5 into the reaction kettle. React at 55°C and 0.15 MPa for 60 min to obtain a high-temperature-resistant, high-voltage-resistant, and anti-breakdown capacitor base film.

[0044] In this embodiment, the enhanced and improved talc powder is prepared by the following method: S1. Perform intercalation treatment on talc to obtain intercalated modified talc: Calcine 1 g of talc at 700°C for 6 h. After cooling, add it to 100 mL of deionized water, add 0.65 g of 2-carboxyethylphenylphosphinic acid, stir and reflux at 70°C for 6 h, let it stand for 2 h, then centrifuge and filter. Vacuum dry the solid product at 90°C and grind it to less than 10 μm to obtain intercalated modified talc. S2. Prepare loaded modified talc: S2-1. Take 2 g of intercalated modified talc and 0.38 g of titanium tetrachloride, add them to 100 mL of deionized water, and ultrasonically disperse for 30 min to obtain mixture 1. S2-2. Take 180 mg of urea, 684 mg of sucrose, 284.5 mg of lutein, and 120 mg of ethylenediamine, add them to 50 mL of deionized water, and stir for 15 min to obtain mixture 2. S2-3. Under stirring, add mixture 2 to mixture 1, ultrasonically disperse for 10 min, then dropwise add 15 mL of a 1 mol / L sodium hydroxide aqueous solution, and react at 35°C for 1 h to obtain a precursor. S2-4. Transfer the precursor to a stainless steel reaction kettle with a polytetrafluoroethylene lining, react at 180°C for 12 h. After the reaction, cool to room temperature, filter, wash the solid product with deionized water, vacuum dry at 90°C for 12 h, and grind to obtain loaded modified talc. S3. Perform organic coating treatment on the loaded modified talc to obtain enhanced and improved talc powder: Take 2 g of the loaded and modified talc, add 100 mL of ethanol to 250 mL of deionized water, ultrasonically disperse for 30 min, then add 7 g of sodium dodecyl sulfate, stir for 10 min, then add 3.5 mL of acrylic acid, adjust the pH value to 4.5 with hydrochloric acid, stir and react at 78 °C for 2 h, let stand for 8 h, filter, wash the solid product with deionized water, vacuum dry at 70 °C for 12 h, grind, and pass through a 10-μm sieve to obtain the enhanced and improved talc powder.

[0045] In this example, the modified barium titanate is prepared by the following method: 1) Take 1 g of polymethyl methacrylate and 50 mL of deionized water, add them to 100 mL of ethanol, and ultrasonically disperse for 30 min; 2) Take 2 g of nano-barium titanate, add it to 100 mL of ethanol, ultrasonically disperse for 30 min, drop the obtained mixture into the product of step 1), stir for 45 min, then adjust the pH to 4.0 with 0.05 mol / L nitric acid, stir and react at 45 °C for 4 h, filter, wash the solid product with ethanol, and vacuum dry at 50 °C for 8 h to obtain the modified barium titanate.

[0046] Example 2 A high-temperature resistant, high-voltage resistant and anti-breakdown capacitor base film, characterized in that its preparation raw materials include, by weight: 100 parts of polypropylene; 27 parts of polyvinylidene fluoride; 8 parts of the enhanced and improved talc powder; 3.5 parts of the modified barium titanate; 2 parts of crosslinking agent; 4.5 parts of compatibilizer; 0.15 part of initiator.

[0047] The crosslinking agent is trimethylolpropane trimethacrylate, and the compatibilizer is maleic anhydride grafted polypropylene.

[0048] The preparation method of the capacitor base film includes the following steps: S1. Stir and mix polypropylene, polyvinylidene fluoride, the enhanced and improved talc powder, the modified barium titanate, and the compatibilizer at 50 °C for 20 min, add the obtained mixture to an extruder and melt and extrude, and control the extrusion temperature at 250 °C; S2. Cool and cast the film, and the cooling temperature is 70 °C; S3. Perform biaxial stretching at 160 °C, with the longitudinal stretching ratio being 4 times and the transverse stretching ratio being 2.5 times to obtain a base film with a thickness of 10 μm; S4. Fluorination treatment: Place the base film in a reaction kettle that has been pre-replaced with nitrogen, and introduce into the reaction kettle a mixed gas composed of fluorine gas and nitrogen in a volume ratio of 1.5:8.5. React at 55 °C and a pressure of 0.15 MPa for 60 minutes to obtain a high-temperature resistant, high-voltage resistant, and anti-breakdown capacitor base film.

[0049] In this embodiment, the preparation method of the enhanced and improved talc powder is the same as that in Example 1.

[0050] In this embodiment, the preparation method of the modified barium titanate is the same as that in Example 1.

[0051] Example 3 A high-temperature resistant, high-voltage resistant, and anti-breakdown capacitor base film, characterized in that its preparation raw materials include, by weight: 100 parts of polypropylene; 25 parts of polyvinylidene fluoride; 10 parts of enhanced and improved talc powder; 4 parts of modified barium titanate; 2.2 parts of crosslinking agent; 5 parts of compatibilizer; 0.15 part of initiator.

[0052] The crosslinking agent is trimethylolpropane trimethacrylate, and the compatibilizer is maleic anhydride grafted polypropylene.

[0053] The preparation method of this capacitor base film includes the following steps: S1. Stir and mix polypropylene, polyvinylidene fluoride, enhanced and improved talc powder, modified barium titanate, and compatibilizer at 50 °C for 20 minutes, and add the obtained mixture to an extruder for melt extrusion, with the extrusion temperature controlled at 260 °C; S2. Cool and cast the film, with the cooling temperature being 70 °C; S3. Perform biaxial stretching at 160 °C, with the longitudinal stretching ratio being 4 times and the transverse stretching ratio being 2.5 times to obtain a base film with a thickness of 10 μm; S4. Fluorination treatment: Place the base film in a reaction kettle that has been pre-replaced with nitrogen, and introduce into the reaction kettle a mixed gas composed of fluorine gas and nitrogen in a volume ratio of 1.5:8.5. React at 55 °C and a pressure of 0.15 MPa for 60 minutes to obtain a high-temperature resistant, high-voltage resistant, and anti-breakdown capacitor base film.

[0054] In this embodiment, the preparation method of the enhanced and improved talc powder is the same as that in Example 1.

[0055] In this embodiment, the preparation method of the modified barium titanate is the same as that in Example 1.

[0056] Comparative Example 1 This example is basically the same as Example 1, except that: in this example, an equal amount of talcum powder (10 μm) is used to replace the enhanced and improved talcum powder in Example 1.

[0057] Comparative Example 2 This example is basically the same as Example 1, except that: the enhanced and improved talcum powder in this example is prepared by the following method: S1. Expand the layer of talc to obtain expanded and modified talc; the specific steps are the same as those in Example 1; S2. Prepare the loaded modified talc: S2-1. Take 2 g of expanded and modified talc and 0.38 g of titanium tetrachloride, add them to 100 mL of deionized water, and ultrasonically disperse for 30 min to obtain Mixture 1; S2-3. Dropwise add 15 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L to Mixture 1 under stirring, and react at 35 °C for 1 h to obtain the precursor; S2-4. Transfer the precursor to a stainless steel reaction kettle lined with polytetrafluoroethylene, react at 180 °C for 12 h, cool to room temperature after the reaction, filter, wash the solid product with deionized water, vacuum dry at 90 °C for 12 h, and grind to obtain the loaded modified talc; S3. Perform organic coating treatment on the loaded modified talc to obtain the enhanced and improved talcum powder; the specific steps are the same as those in Example 1.

[0058] Comparative Example 3 This example is basically the same as Example 1, except that: the enhanced and improved talcum powder in this example is prepared by the following method: S1. Expand the layer of talc to obtain expanded and modified talc; the specific steps are the same as those in Example 1; S2. Prepare the loaded modified talc: S2-1. Take 2 g of expanded and modified talc and add it to 100 mL of deionized water, and ultrasonically disperse for 30 min to obtain Mixture 1; S2-2. Take 180 mg of urea, 684 mg of sucrose, 284.5 mg of lutein, and 120 mg of ethylenediamine, add them to 50 mL of deionized water, and stir for 15 min to obtain Mixture 2; S2-3. Add Mixture 2 to Mixture 1 under stirring, ultrasonically disperse for 10 min, then dropwise add 15 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L, and react at 35 °C for 1 h to obtain the precursor; S2-4. Transfer the precursor to a stainless steel reaction kettle lined with polytetrafluoroethylene, react at 180 °C for 12 h, cool to room temperature after the reaction, filter, wash the solid product with deionized water, vacuum dry at 90 °C for 12 h, and grind to obtain the loaded modified talc; S3. The loaded modified talc is subjected to organic coating treatment to obtain enhanced improved talc powder; the specific steps are the same as those in Example 1.

[0059] Comparative Example 4 This example is basically the same as Example 1, except that the loaded modified talc prepared in Example 1 is used instead of the enhanced improved talc powder as the raw material for the capacitor base film.

[0060] Comparative Example 5 This example is basically the same as Example 1, with the only difference being that an equal amount of nano-barium titanate is used in this example to replace the modified barium titanate in Example 1.

[0061] Comparative Example 6 This example is basically the same as Example 1, except that the step of preparing the capacitor base film does not include fluorination treatment.

[0062] Performance Testing The following performance tests were performed on the capacitor base films prepared in the examples and comparative examples: 1. Breakdown voltage test An insulation withstand voltage tester (HZJY-115, Hezhong Electric) was used with a test time of 15 s and a cut-off voltage of 6 kV. Test points were taken at random positions every 100 mm along the 1000 mm TD direction, and the test data were recorded. The average value of the test data at all points was recorded as the breakdown voltage test result.

[0063] 2. Tensile strength test With reference to ASTM D882-12 "Standard Test Method for Tensile Properties of Film and Sheeting", the tensile breaking strength of the polypropylene capacitor base films prepared in the examples and comparative examples was tested using a universal tensile testing machine. 3. Thermal shrinkage test The heat shrinkage of the polypropylene capacitor base films prepared in the examples and comparative examples was tested at 160°C according to ASTM D2732; 4. Thermal oxygen aging resistance test Heat aging resistance: The polypropylene capacitor base films prepared in the example and comparative example were placed in hot air at 100°C for artificial accelerated aging for 150 hours. After cooling to room temperature, the longitudinal tensile strength was measured again. The heat aging resistance was measured by the retention rate of the longitudinal tensile strength. The larger the value, the better the heat aging resistance.

[0064] The breakdown voltage, tensile strength, thermal shrinkage and thermal oxygen aging test results are shown in Table 1 and Figures 1-5 As shown: Table 1 As can be seen from the test results, the container base films prepared in Examples 1-3 have high mechanical strength, and at the same time have excellent high temperature resistance, heat and oxygen aging resistance, and high voltage breakdown resistance; in Comparative Example 1, talcum powder was used to replace the enhanced talcum powder, and the comprehensive performance decreased significantly; in Comparative Example 2, no carbon dots were loaded, and the heat and oxygen aging resistance decreased significantly; in Comparative Example 3, the decrease in breakdown voltage and heat and oxygen aging resistance was attributed to the absence of titanium dioxide in the enhanced talcum powder; in Comparative Example 4, the reason for the decrease in comprehensive performance was that the enhanced talcum powder was not treated with organic matter coating; in Comparative Example 5, nano-barium titanate was used to replace modified barium titanate, and the breakdown voltage decreased; in Comparative Example 6, the breakdown voltage decreased due to the lack of fluorination treatment.

[0065] 5. Antioxidant Performance Test The enhanced talcum powder prepared in Example 1, Comparative Example 2, and Comparative Example 3 was respectively added to ethanol and ultrasonically dispersed for 30 min to prepare a dispersion with a concentration of 1 mg / mL, and the antioxidant performance of the dispersion was detected within a certain time using a DPPH free radical scavenging rate detection kit (Shanghai Enzyme-linked Biology).

[0066] Determination principle: DPPH free radicals have a single electron, and its alcohol solution is purple with a strong absorption at 515 nm. When an antioxidant is present, the DPPH free radicals are scavenged, the color of its solution becomes lighter, the absorbance at 515 nm decreases, and within a certain range, the change in absorbance is proportional to the degree of free radical scavenging; the ability of the sample to scavenge DPPH free radicals is reflected by the degree of decrease in absorbance.

[0067] Refer to Figure 6 , which is the test result of antioxidant performance. It can be seen that the enhanced talcum powder prepared in Example 1 showed good antioxidant ability. The comparison between Comparative Example 2 and Example 1 shows that the antioxidant performance comes from the loaded carbon dots, and the comparison between Comparative Example 2 and Example 1 shows that the doping of titanium dioxide plays a role in improving the antioxidant performance.

[0068] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A high-temperature and high-voltage resistant anti-breakdown capacitor base film, characterized in that, The raw materials for its preparation include, by weight: 100 parts of polypropylene; 17 - 36 parts of polyvinylidene fluoride; 3 - 12 parts of enhanced and improved talc powder; 1 - 6.5 parts of modified barium titanate; 1 - 6 parts of cross - linker; 2 - 10 parts of compatibilizer; 0.05 - 2 parts of initiator; The enhanced and improved talc powder is prepared by the following method: S1. Expand the layer of talc: Calcinate the talc, cool it and add it to deionized water, add 2 - carboxyethylphenylphosphinic acid, stir and reflux under heating, let it stand and then centrifuge and filter, vacuum - dry the solid product and grind it to obtain expanded - modified talc; S2. Prepare loaded - modified talc, and in - situ synthesize titanium dioxide - carbon dot composite particles on the expanded - modified talc: S2 - 1. Add the expanded - modified talc and titanium tetrachloride to deionized water, and ultrasonically disperse to obtain mixture 1; S2-2. Take urea, Sucrose , lutein, and ethylenediamine and add them to deionized water, then stir to obtain mixture 2; S2 - 3. Under stirring, add mixture 2 to mixture 1, ultrasonically disperse, and then dropwise add an aqueous sodium hydroxide solution, heat and react to obtain a precursor; S2 - 4. Transfer the precursor to a reaction kettle, react under heating, cool after the reaction ends, filter, wash the solid product, vacuum - dry and grind to obtain loaded - modified talc; S3. Conduct an organic - coating treatment on the loaded - modified talc: Take the loaded - modified talc and ethanol, add them to deionized water, ultrasonically disperse, then add sodium dodecyl sulfate, stir, then add acrylic acid, adjust the pH with hydrochloric acid, stir and react under heating, let it stand, filter, wash the solid product, vacuum - dry and grind to obtain the enhanced and improved talc powder; The modified barium titanate is prepared by the following method: 1) Take 0.5 - 2 g of polymethyl methacrylate and 25 - 100 mL of deionized water, add them to 50 - 200 mL of ethanol, and ultrasonically disperse for 15 - 60 min; 2) Take 1 - 4 g of nano - barium titanate, add it to 50 - 200 mL of ethanol, ultrasonically disperse for 15 - 60 min, drop the obtained mixture into the product of step 1), stir for 30 - 90 min, then adjust the pH to 3.0 - 5.0 with 0.02 - 0.2 mol / L nitric acid, stir and react at 30 - 60 °C for 2 - 8 h, filter, wash the solid product with ethanol, and vacuum - dry at 30 - 50 °C for 4 - 12 h to obtain modified barium titanate.

2. The high-temperature and high-voltage resistant anti-breakdown capacitor base film according to claim 1, wherein Step S1 is specifically: Calcinate 0.5 - 2 g of talc at 600 - 750 °C for 3 - 8 h, cool it and add it to 50 - 200 mL of deionized water, add 0.35 - 1.3 g of 2 - carboxyethylphenylphosphinic acid, stir and reflux at 60 - 80 °C for 3 - 12 h, let it stand for 1 - 4 h and then centrifuge and filter, vacuum - dry the solid product at 70 - 100 °C, and grind it to less than 5 - 20 μm to obtain expanded - modified talc.

3. The high-temperature and high-voltage resistant anti-breakdown capacitor base film according to claim 1, wherein, Step S2 is specifically: S2 - 1. Take 1 - 42 g of expanded - modified talc and 0.19 - 0.76 g of titanium tetrachloride, add them to 50 - 200 mL of deionized water, and ultrasonically disperse for 15 - 60 min to obtain mixture 1; S2-2. Take 90 - 360 mg of urea, 342 - 1368 mg Sucrose , 142 - 569 mg of lutein, 60 - 240 mg of ethylenediamine and add them to 25 - 100 mL of deionized water, stir for 5 - 30 min to obtain Mixture 2; S2-3. While stirring, add mixture 2 to mixture 1, ultrasonically disperse for 5 - 20 min, then dropwise add 7.5 - 30 mL of sodium hydroxide aqueous solution with a concentration of 0.5 - 2 mol / L, react at 30 - 40 °C for 0.5 - 2 h to obtain a precursor; S2-4. Transfer the precursor to a stainless steel reactor lined with polytetrafluoroethylene, react at 160 - 210 °C for 6 - 24 h, after the reaction is completed, cool to room temperature, filter, wash the solid product with deionized water, vacuum dry at 70 - 100 °C for 6 - 24 h, and grind to obtain the loaded modified talc.

4. The high-temperature and high-voltage resistant anti-breakdown capacitor base film according to claim 1, characterized in that, Step S3 is specifically as follows: Take 1 - 4 g of loaded modified talc and 50 - 200 mL of ethanol, add them to 125 - 500 mL of deionized water, ultrasonically disperse for 15 - 60 min, then add 3.5 - 14 g of sodium dodecyl sulfate, stir for 5 - 20 min, then add 1.75 - 7 mL of acrylic acid, adjust the pH value to 3 - 5 with hydrochloric acid, stir and react at 70 - 82 °C for 1 - 4 h, let stand for 4 - 16 h, filter, wash the solid product with deionized water, vacuum dry at 50 - 80 °C for 6 - 24 h, grind, and pass through a 5 - 20 μm sieve to obtain the enhanced and improved talc powder.

5. The high-temperature and high-voltage resistant anti-breakdown capacitor base film according to claim 1, wherein, The enhanced and improved talc powder is prepared by the following method: S1. Expand the layer of talc to obtain expanded modified talc: Calcine 1 g of talc at 700 °C for 6 h, after cooling, add it to 100 mL of deionized water, add 0.65 g of 2 - carboxyethylphenylphosphinic acid, stir and reflux at 70 °C for 6 h, let stand for 2 h, then centrifuge and filter, vacuum dry the solid product at 90 °C, and grind it to below 10 μm to obtain the expanded modified talc; S2. Prepare the loaded modified talc: S2-1. Take 2 g of expanded modified talc and 0.38 g of titanium tetrachloride, add them to 100 mL of deionized water, ultrasonically disperse for 30 min to obtain mixture 1; S2-2. Take 180 mg of urea, 684 mg Sucrose , 284.5 mg of lutein, and 120 mg of ethylenediamine and add them to 50 mL of deionized water, stir for 15 min to obtain Mixture 2; S2-3. While stirring, add mixture 2 to mixture 1, ultrasonically disperse for 10 min, then dropwise add 15 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L, react at 35 °C for 1 h to obtain a precursor; S2-4. Transfer the precursor to a stainless steel reactor lined with polytetrafluoroethylene, react at 180 °C for 12 h, after the reaction is completed, cool to room temperature, filter, wash the solid product with deionized water, vacuum dry at 90 °C for 12 h, and grind to obtain the loaded modified talc; S3. Conduct an organic coating treatment on the loaded modified talc to obtain the enhanced and improved talc powder: Take 2 g of loaded modified talc and 100 mL of ethanol, add them to 250 mL of deionized water, ultrasonically disperse for 30 min, then add 7 g of sodium dodecyl sulfate, stir for 10 min, then add 3.5 mL of acrylic acid, adjust the pH value to 4.5 with hydrochloric acid, stir and react at 78 °C for 2 h, let stand for 8 h, filter, wash the solid product with deionized water, vacuum dry at 70 °C for 12 h, grind, and pass through a 10 μm sieve to obtain the enhanced and improved talc powder.

6. The high-temperature and high-voltage resistant anti-breakdown capacitor base film according to claim 1, characterized in that, The modified barium titanate is prepared by the following method: 1) Take 1 g of polymethyl methacrylate and 50 mL of deionized water, add them to 100 mL of ethanol, and ultrasonically disperse for 30 min; 2) Take 2 g of nano-barium titanate, add it to 100 mL of ethanol, ultrasonically disperse for 30 min, drop the obtained mixture into the product of step 1), stir for 45 min, then adjust the pH to 4.0 with 0.05 mol / L nitric acid, stir and react at 45 °C for 4 h, filter, wash the solid product with ethanol, and vacuum dry at 50 °C for 8 h to obtain modified barium titanate.

7. The high-temperature and high-voltage resistant anti-breakdown capacitor base film according to claim 1, wherein The crosslinking agent is one or two of trimethylolpropane trimethacrylate and pentaerythritol triacrylate, and the compatibilizer is maleic anhydride grafted polypropylene.

8. A method for preparing a high-temperature resistant, high-voltage resistant and breakdown-proof capacitor base film according to any one of claims 1-7, characterized in that, It includes the following steps: S1. Stir and mix polypropylene, polyvinylidene fluoride, reinforcing and improving talc powder, modified barium titanate, compatibilizer, and initiator at 40 - 60 °C for 10 - 40 min, add the obtained mixture to an extruder for melt extrusion, and control the extrusion temperature at 220 °C - 280 °C; S2. Cool and cast the film, and the cooling temperature is 50 - 80 °C; S3. Carry out biaxial stretching at 150 - 175 °C, with the longitudinal stretching ratio being 2.5 - 5.5 times and the transverse stretching ratio being 2 - 3 times to obtain a base film with a thickness of 1 - 20 μm; S4. Fluorination treatment: Place the base film in a reaction kettle pre-replaced with nitrogen, introduce a mixed gas of fluorine gas and nitrogen into the reaction kettle, and react at 40 - 65 °C and a pressure of 0.05 - 0.4 MPa for 30 - 120 min to obtain a high-temperature resistant, high-voltage resistant, and anti-breakdown capacitor base film.

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