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CN-121991388-A - High-performance PP capacitor base film and preparation method thereof

CN121991388ACN 121991388 ACN121991388 ACN 121991388ACN-121991388-A

Abstract

The invention relates to the field of high-temperature resistant film capacitor dielectric materials, in particular to a high-performance PP capacitor base film and a preparation method thereof, wherein the high-performance PP capacitor base film comprises a special material obtained by melting and granulating capacitance-grade isotactic polypropylene resin, a multifunctional macromolecular modifier, an antioxidant and a crosslinking catalyst; the special material is extruded and cast into thick sheets, and the high-performance PP capacitor base film is obtained through preheating, longitudinal and transverse stretching, water vapor heat setting, cooling and rolling and curing. The modifier is prepared by cooling (4-hydroxyphenyl) (4-trifluoromethylphenyl) ketone, an acid binding agent and a solvent, dropwise adding methacryloyl chloride for reaction and purification to obtain (4-methacryloxyphenyl) (4-trifluoromethylphenyl) ketone, and carrying out melt grafting, granulating and drying on the (4-hydroxyphenyl) (4-trifluoromethylphenyl) ketone, polyolefin skeleton resin, vinyl trimethoxy silane and an initiator.

Inventors

  • WANG RUNXIAO
  • XIA JINGJING
  • LIU YUANCHAO
  • TONG GUOQING
  • WANG FENG

Assignees

  • 扬州博恒新能源材料科技有限公司

Dates

Publication Date
20260508
Application Date
20260409

Claims (10)

  1. 1. The preparation method of the high-performance PP capacitor base film is characterized by comprising the following steps of: uniformly mixing capacitance-grade isotactic polypropylene resin, a multifunctional macromolecular modifier, an antioxidant and a crosslinking catalyst, and carrying out melt blending granulation to obtain a special material; melting and extruding the special material, and casting the special material onto a quenching roller to form a thick sheet; Preheating a thick sheet, longitudinally stretching, transversely stretching, performing heat setting treatment after stretching, introducing water vapor with the relative humidity of 60-80% into a heat setting area, cooling and rolling, and curing to obtain a high-performance PP capacitor base film; Wherein, the preparation of the multifunctional macromolecular modifier comprises the following steps: Step (1), mixing (4-hydroxyphenyl) (4-trifluoromethyl phenyl) ketone, an acid binding agent and a solvent, cooling, dropwise adding methacryloyl chloride, reacting, washing, drying and purifying to obtain (4-methacryloxyphenyl) (4-trifluoromethyl phenyl) ketone; And (2) uniformly mixing polyolefin skeleton resin, (4-methacryloxyphenyl) (4-trifluoromethyl phenyl) ketone, vinyl trimethoxy silane and an initiator, performing melt reactive grafting, removing volatile matters, granulating, and drying to obtain the multifunctional macromolecular modifier.
  2. 2. The preparation method of the high-performance PP capacitor base film according to claim 1, wherein the weight ratio of the capacitance grade isotactic polypropylene resin to the multifunctional macromolecular modifier to the antioxidant to the crosslinking catalyst is (85-95): 5-15): 0.1-0.5): 0.05-0.2.
  3. 3. The method for producing a high performance PP capacitor base film according to claim 1, wherein in the step (1), the molar ratio of (4-hydroxyphenyl) (4-trifluoromethylphenyl) methanone, the acid binding agent and methacryloyl chloride is 1 (1-1.5): 1-1.5; The solvent is anhydrous dichloromethane; The acid binding agent is triethylamine.
  4. 4. The method for producing a high-performance PP capacitor base film according to claim 1, wherein in the step (2), the weight ratio of the polyolefin backbone resin, (4-methacryloxyphenyl) (4-trifluoromethylphenyl) methanone, vinyltrimethoxysilane and initiator is 100 (3-8): (2-5): (0.1-0.3).
  5. 5. The method for producing a high-performance PP capacitor base film according to claim 1, wherein in the step (2), the polyolefin backbone resin is a high melt strength isotactic polypropylene or an ethylene-octene copolymer; The initiator is 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane.
  6. 6. The method for producing a high performance PP capacitor base film according to claim 1, wherein in the step (1), the cooling temperature is 0 ℃, the reaction temperature is 25 ℃, and the reaction time is 10-14 hours; In the step (2), the melt reactive grafting is carried out in a double-screw extruder, the temperature of each area of the extruder is controlled to be 170-200 ℃, and the volatile is removed by adopting a vacuumizing mode.
  7. 7. The method for preparing the high-performance PP capacitor base film according to claim 1, wherein the melt blending granulation is performed in a twin-screw extruder at 190-220 ℃; the melt extrusion is carried out in a single screw extruder at a temperature of 220-240 ℃ and a quench roll at a temperature of 80-90 ℃.
  8. 8. The method for producing a high performance PP capacitor base film according to claim 1, wherein the preheating temperature for longitudinal stretching is 140-150 ℃, and the stretching ratio for longitudinal stretching is 4-6 times; The temperature of transverse stretching is 155-165 ℃, and the stretching multiple of transverse stretching is 6-9 times; The temperature of the heat setting treatment is 160 ℃, and the relative humidity of the water vapor is 60% -80%; the curing temperature was 60 ℃, the relative humidity of curing was 80%, and the curing time was 48 hours.
  9. 9. The method for preparing the high-performance PP capacitor base film according to claim 1, wherein the isotacticity of the capacitance level isotactic polypropylene resin is more than or equal to 98%, the ash content is less than or equal to 30ppm, and the melt index is 1.5-3.0g/10min; the crosslinking catalyst is dibutyl tin dilaurate or dibutyl tin diacetate.
  10. 10. A high performance PP capacitor base film prepared by the preparation method of any one of claims 1-9.

Description

High-performance PP capacitor base film and preparation method thereof Technical Field The invention relates to the field of high-temperature-resistant film capacitor dielectric materials, in particular to a high-performance PP capacitor base film and a preparation method thereof. Background The film capacitor is widely applied to various fields of electronic power and modern industry, and the existing capacitor base film is developing towards the trend of high temperature resistance, high breakdown field strength and low loss on the premise of ensuring basic electrical performance, wherein the insulation stability of the base film under extreme working conditions is more and more important, and particularly in a new generation of high power density power system, the requirement on the high temperature withstand voltage index of the film capacitor is extremely strict; The existing pure isotactic polypropylene film is commonly applied at normal temperature, but in a high-temperature environment, the slippage and the relaxation of amorphous area chains of the existing pure isotactic polypropylene film are obviously enhanced, so that the free volume in the material is increased, and the breakdown field strength is further reduced sharply; however, due to the limitation of technical conditions, in the past, in order to improve the high temperature resistance of the base film, a physical blending strategy of a small molecular voltage stabilizer is mostly adopted, and because covalent bond anchoring is not formed between the small molecular voltage stabilizer and a matrix, thermomechanical migration and precipitation are easy to occur under the action of high temperature and strong electric field, so that the local electric field is severely distorted, the modification control means is limited, and the high temperature insulation performance of the conventional polypropylene film cannot meet the development requirement of a high temperature resistant capacitor. Disclosure of Invention The invention aims to provide a high-performance PP capacitor base film and a preparation method thereof, which are used for solving the problems in the background technology. The existing pure isotactic polypropylene film and small molecule blending modification technology has obvious defects when facing the extreme working conditions of high temperature and strong electric field, namely the free volume of the pure film is obviously increased at high temperature to cause the rapid reduction of breakdown field intensity, and the small molecule voltage stabilizer is extremely easy to generate thermomechanical migration precipitation to cause the serious distortion of local electric field, so that the high-performance PP capacitor base film which can covalently anchor deep trap groups through chemical bonds to stop migration precipitation and construct a microscopic silica three-dimensional crosslinked network in situ to effectively limit the sliding of molecular chains and the preparation method thereof are required. The technical scheme of the invention comprises the steps of uniformly mixing capacitance-grade isotactic polypropylene resin, a multifunctional macromolecular modifier, an antioxidant and a crosslinking catalyst, and carrying out melt blending granulation to obtain a special material; melting and extruding the special material, and casting the special material onto a quenching roller to form a thick sheet; Preheating a thick sheet, longitudinally stretching, transversely stretching, performing heat setting treatment after stretching, introducing water vapor with the relative humidity of 60-80% into a heat setting area, cooling and rolling, and curing to obtain a high-performance PP capacitor base film; Wherein, the preparation of the multifunctional macromolecular modifier comprises the following steps: Step (1), mixing (4-hydroxyphenyl) (4-trifluoromethyl phenyl) ketone, an acid binding agent and a solvent, cooling, dropwise adding methacryloyl chloride, reacting, washing, drying and purifying to obtain (4-methacryloxyphenyl) (4-trifluoromethyl phenyl) ketone; And (2) uniformly mixing polyolefin skeleton resin, (4-methacryloxyphenyl) (4-trifluoromethyl phenyl) ketone, vinyl trimethoxy silane and an initiator, performing melt reactive grafting, removing volatile matters, granulating, and drying to obtain the multifunctional macromolecular modifier. Preferably, the capacitance grade isotactic polypropylene resin, the multifunctional macromolecular modifier, the antioxidant and the crosslinking catalyst are in the weight part ratio of (85-95): (5-15): (0.1-0.5): (0.05-0.2). Preferably, in the step (1), the molar ratio of the (4-hydroxyphenyl) (4-trifluoromethylphenyl) methanone, the acid binding agent and the methacryloyl chloride is 1 (1-1.5): 1-1.5; The solvent is anhydrous dichloromethane; The acid binding agent is triethylamine. Preferably, in the step (2), the weight part ratio of the polyolefin backbone resin, (4-me