High-voltage-resistant thin film for wind power capacitor and preparation method of high-voltage-resistant thin film

Abstract

The invention discloses a high-voltage-resistant film for a wind power capacitor and a preparation method thereof, and belongs to the technical field of capacitor films, the high-voltage-resistant film comprises the following raw materials by weight: 50-80 parts of polypropylene resin, 3-5 parts of a modified filler, 0.2-0.5 part of an antioxidant, and 0.3-0.5 part of a nucleating agent; the preparation method comprises the following steps: uniformly mixing the raw materials, melting at 170-190 DEG C, filtering, exhausting for 10-12 times, carrying out hot press molding at 20 MPa, forming a thick sheet, stretching, and preparing the thin film to prepare the high-voltage-resistant thin film for the wind power capacitor, and when the modified filler is added into polypropylene, on one hand, the high-temperature resistance of the polypropylene material can be improved, and on the other hand, the voltage resistance of a matrix can be improved, so that the high-voltage-resistant thin film for the wind power capacitor is prepared. And moreover, the compatibility with the matrix polypropylene can be improved by grafting the polymer to the surface of the talcum powder.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitor films, and in particular to a high-voltage-resistant film for wind power capacitors and a preparation method thereof. Background Art

[0002] Existing metallized capacitor films are widely used in electronics, home appliances, communications, electricity, electrified railways, hybrid vehicles, wind power generation, solar power generation and other industries. As an important energy storage device, capacitors have developed from the initial simple form to today's complex devices. Compared with batteries and electrochemical capacitors, dielectric capacitors have higher operating voltage and power density, longer life and greater cycle stability. According to the dielectric material, they can be divided into: ceramic capacitors, electrolytic capacitors, paper dielectric capacitors, polymer film capacitors, etc. With the development of advanced electronics and power systems, film capacitors with high energy storage performance have become particularly important. Polymer-based materials stand out because of their flexibility, cost-effectiveness and customizable functional characteristics, and become the main dielectric of film capacitors. These film capacitors have gradually begun to be widely used in smart grids, new energy vehicles and other fields due to their advantages such as high breakdown field strength, high power density, small dielectric loss, small size and low cost. However, due to its low dielectric constant, it is difficult to improve its capacitance and energy storage density, which hinders the further development of film capacitors.

[0003] Chinese patent application number 201710580920.9 discloses a method for preparing a polypropylene film for high-temperature resistant capacitors, wherein the polypropylene raw material is put into an extruder for extrusion, sheet casting, biaxial synchronous stretching and heat setting to form a film, and then the film is cooled, thickness measured, trimmed and corona treated, rolled and subjected to secondary aging treatment to obtain a polypropylene film for high-temperature resistant capacitors; the above improvements to the film are mainly concentrated on the preparation process, and the performance improvement of the prepared film is limited, so research on new dielectric materials has become a focus of attention. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a high-voltage film for wind power capacitors and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A high-voltage film for wind power capacitors, comprising the following raw materials in parts by weight: 50-80 parts of polypropylene resin, 3-5 parts of modified filler, 0.2-0.5 parts of antioxidant, and 0.3-0.5 parts of nucleating agent; The modified filler is prepared by the following steps: Step S1, adding talcum powder to a 20% by mass sodium hydroxide aqueous solution, heating to 80-90° C., stirring at high speed and reacting for 6 hours, washing with deionized water after the reaction to obtain modified talcum powder, then adding the obtained modified talcum powder to a 75% by volume ethanol aqueous solution, adjusting the system pH to 4-5, adding KH570, heating to 50-65° C., stirring at a uniform speed and reacting for 4-6 hours, cooling to room temperature after the reaction to obtain modified talcum powder, controlling the dosage ratio of talcum powder to sodium hydroxide aqueous solution to be 5-10 g: 150-250 mL, and the dosage ratio of modified talcum powder, KH570 and ethanol aqueous solution to be 5-10 g: 1-2 g: 100 mL; In step S1, the surface of talc is first treated with sodium hydroxide to introduce hydroxyl groups on the surface of talc, and then a silane coupling agent KH570 is added. KH570 is hydrolyzed and condensed with the hydroxyl groups on the surface of talc to introduce carbon-carbon double bonds on the surface of talc to obtain modified talc; Step S2, adding the prepared modified talc and maleimide to ethyl acetate, ultrasonically dispersing and adding dibenzoyl peroxide, heating to 70-90° C., stirring at a uniform speed and reacting for 1 hour, and obtaining grafted talc after the reaction, wherein the amount ratio of modified talc, maleimide and ethyl acetate is controlled to be 5-10 g: 2-3 g: 100 mL; In step S2, the carbon-carbon double bonds on the modified talc powder are polymerized with the unsaturated carbon-carbon double bonds on the maleimide, and then the prepolymer containing the maleimide structure is implanted on the surface of the talc powder to obtain the grafted talc powder.

[0006] Step S3, adding 4,4'-dichlorobenzil and grafted talc to N,N-dimethylformamide, stirring at a uniform speed, adding cuprous iodide and N,N-dimethyl-1,2-ethylenediamine, mixing evenly, heating to 100°C, reacting for 24 hours under a nitrogen atmosphere to obtain a modified filler, wherein the amount ratio of grafted talc, 4,4'-dichlorobenzil and N,N-dimethylformamide is controlled to be 5-10g:3-5g:50-80mL, the weight ratio of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine is 1:1, and the sum of the weight of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine is 3-5% of the weight of the grafted talc.

[0007] In step S3, cuprous iodide and N,N-dimethyl-1,2-ethylenediamine are used as a catalyst system, chlorine on 4,4'-dichlorobenzil reacts with imine on grafted talc, and benzil compounds are grafted onto the surface of talc. Talc can be used as an excellent heat-resistant modifier to improve the heat resistance of polypropylene, and the grafted benzil compounds can play a role as a voltage stabilizer. When the modified filler is added to polypropylene, on the one hand, the high temperature resistance of the polypropylene material can be improved, and on the other hand, the voltage resistance of the matrix can be improved. Moreover, by grafting a polymer onto the surface of talc, the compatibility with the matrix polypropylene can be improved.

[0008] Furthermore, the antioxidant is antioxidant 1010 or antioxidant 168.

[0009] Furthermore, the nucleating agent is a long-chain linear saturated carboxylic acid sodium salt nucleating agent.

[0010] A method for preparing a high-voltage film for a wind power capacitor comprises the following steps: The raw materials are mixed uniformly, melted at 170-190° C., filtered and vented 10-12 times, hot-pressed at 20 MPa to form a thick sheet, stretched and made into a film, thereby obtaining a high-voltage film for wind power capacitors.

[0011] Furthermore, the exhaust is controlled every 8-10 seconds.

[0012] Beneficial effects of the present invention: The present invention prepares a high-pressure-resistant film, which uses polypropylene as a matrix, and imparts excellent performance to the film by adding a modified filler. During the preparation process, the surface of the talc powder is first treated with sodium hydroxide to introduce hydroxyl groups on the surface of the talc powder, and then a silane coupling agent KH570 is added. KH570 is hydrolyzed and condensed with the hydroxyl groups on the surface of the talc powder, thereby introducing carbon-carbon double bonds on the surface of the talc powder to obtain modified talc powder. Then, the carbon-carbon double bonds on the modified talc powder are polymerized with the unsaturated carbon-carbon double bonds on the maleimide, and then a prepolymer containing a maleimide structure is connected to the surface of the talc powder to obtain a grafted talc powder. powder, and finally, with the action of cuprous iodide and N, N-dimethyl-1, 2-ethylenediamine as catalysts, the chlorine on 4, 4'-dichlorobenzil reacts with the imine on the grafted talc powder, and the benzil compound is connected to the surface of the talc powder. The talc powder can be used as an excellent heat-resistant modifier to improve the heat resistance of polypropylene, and the connected benzil compound can play the role of a voltage stabilizer. When the modified filler is added to polypropylene, on the one hand, the high temperature resistance of the polypropylene material can be improved, and on the other hand, the voltage resistance of the matrix can be improved. Moreover, by connecting the polymer on the surface of the talc powder, the compatibility with the matrix polypropylene can be improved. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] Example 1: A high-voltage film for wind power capacitors, comprising the following raw materials in parts by weight: 50 parts of polypropylene resin, 3 parts of modified filler, 0.2 parts of antioxidant, and 0.3 parts of nucleating agent; A method for preparing a high-voltage film for a wind power capacitor comprises the following steps: The raw materials were mixed evenly, melted at 170°C, filtered and vented 10 times, hot-pressed at 20 MPa to form a thick sheet, stretched and made into a film to obtain a high-voltage film for wind power capacitors. The venting was controlled every 8 seconds.

[0015] The modified filler is prepared by the following steps: Step S1, adding talcum powder to a 20% sodium hydroxide aqueous solution by mass fraction, heating to 80° C., stirring at high speed and reacting for 6 hours, washing with deionized water after the reaction to obtain modified talcum powder, then adding the obtained modified talcum powder to a 75% ethanol aqueous solution by volume fraction, adjusting the system pH to 4-5, adding KH570, heating to 50° C., stirring at a uniform speed and reacting for 4 hours, cooling to room temperature after the reaction to obtain modified talcum powder, controlling the dosage ratio of talcum powder to sodium hydroxide aqueous solution to be 5g:150mL, and the dosage ratio of modified talcum powder, KH570 and ethanol aqueous solution to be 5g:1g:100mL; Step S2, adding the prepared modified talc and maleimide to ethyl acetate, ultrasonically dispersing and adding dibenzoyl peroxide, heating to 70° C., stirring at a uniform speed and reacting for 1 hour, and obtaining grafted talc after the reaction, wherein the amount ratio of the modified talc, maleimide and ethyl acetate is controlled to be 5 g:2 g:100 mL; Step S3, adding 4,4'-dichlorobenzil and grafted talc to N,N-dimethylformamide, stirring at a uniform speed, adding cuprous iodide and N,N-dimethyl-1,2-ethylenediamine, mixing evenly, heating to 100°C, reacting for 24 hours under a nitrogen atmosphere to obtain a modified filler, controlling the amount ratio of grafted talc, 4,4'-dichlorobenzil and N,N-dimethylformamide to be 5g:3g:50mL, the weight ratio of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine to be 1:1, and the sum of the weight of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine to be 3% of the weight of grafted talc.

[0016] The antioxidant is antioxidant 1010 or antioxidant 168.

[0017] The nucleating agent is a long-chain linear saturated carboxylic acid sodium salt nucleating agent, and its model is HAV101.

[0018] Example 2: A high-voltage film for wind power capacitors, comprising the following raw materials in parts by weight: 65 parts of polypropylene resin, 4 parts of modified filler, 0.4 parts of antioxidant, and 0.4 parts of nucleating agent; A method for preparing a high-voltage film for a wind power capacitor comprises the following steps: The raw materials were mixed evenly, melted at 180°C, filtered and vented 11 times, hot-pressed at 20 MPa to form a thick sheet, stretched and made into a film to obtain a high-voltage film for wind power capacitors. The venting was controlled every 8 seconds.

[0019] The modified filler is prepared by the following steps: Step S1, adding talcum powder to a 20% sodium hydroxide aqueous solution by mass fraction, heating to 85° C., stirring at high speed and reacting for 6 hours, washing with deionized water after the reaction to obtain modified talcum powder, then adding the prepared modified talcum powder to a 75% ethanol aqueous solution by volume fraction, adjusting the system pH to 4-5, adding KH570, heating to 60° C., stirring at a uniform speed and reacting for 5 hours, cooling to room temperature after the reaction to obtain modified talcum powder, controlling the dosage ratio of talcum powder to sodium hydroxide aqueous solution to be 8g:200mL, and the dosage ratio of modified talcum powder, KH570 and ethanol aqueous solution to be 8g:1.5g:100mL; Step S2, adding the prepared modified talc and maleimide to ethyl acetate, ultrasonically dispersing and adding dibenzoyl peroxide, heating to 80°C, stirring at a uniform speed and reacting for 1 hour, and obtaining grafted talc after the reaction, wherein the amount ratio of the modified talc, maleimide and ethyl acetate is controlled to be 8g:2.5g:100mL; Step S3, adding 4,4'-dichlorobenzil and grafted talc to N,N-dimethylformamide, stirring at a uniform speed, adding cuprous iodide and N,N-dimethyl-1,2-ethylenediamine, mixing evenly, heating to 100°C, reacting for 24 hours under a nitrogen atmosphere to obtain a modified filler, controlling the amount ratio of grafted talc, 4,4'-dichlorobenzil and N,N-dimethylformamide to be 8g:4g:60mL, the weight ratio of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine to be 1:1, and the sum of the weight of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine to be 4% of the weight of grafted talc.

[0020] The antioxidant is antioxidant 1010 or antioxidant 168.

[0021] The nucleating agent is a long-chain linear saturated carboxylic acid sodium salt nucleating agent, and its model is HAV101.

[0022] Example 3: A high-voltage film for wind power capacitors, comprising the following raw materials in parts by weight: 80 parts of polypropylene resin, 5 parts of modified filler, 0.5 parts of antioxidant, and 0.5 parts of nucleating agent; A method for preparing a high-voltage film for a wind power capacitor comprises the following steps: The raw materials were mixed evenly, melted at 190°C, filtered, vented 12 times, hot-pressed at 20 MPa to form a thick sheet, stretched, and made into a film to obtain a high-voltage film for wind power capacitors. The venting was controlled every 10 seconds.

[0023] The modified filler is prepared by the following steps: Step S1, adding talcum powder to a 20% by mass sodium hydroxide aqueous solution, heating to 90° C., stirring at high speed and reacting for 6 hours, washing with deionized water after the reaction to obtain modified talcum powder, then adding the obtained modified talcum powder to a 75% by volume ethanol aqueous solution, adjusting the system pH to 5, adding KH570, heating to 65° C., stirring at a uniform speed and reacting for 6 hours, cooling to room temperature after the reaction to obtain modified talcum powder, controlling the amount ratio of talcum powder to sodium hydroxide aqueous solution to be 10 g: 250 mL, and the amount ratio of modified talcum powder, KH570 and ethanol aqueous solution to be 10 g: 2 g: 100 mL; Step S2, adding the prepared modified talc and maleimide to ethyl acetate, ultrasonically dispersing and adding dibenzoyl peroxide, heating to 90° C., stirring at a uniform speed and reacting for 1 hour, and obtaining grafted talc after the reaction, wherein the amount ratio of the modified talc, maleimide and ethyl acetate is controlled to be 10 g:3 g:100 mL; Step S3, adding 4,4'-dichlorobenzil and grafted talc to N,N-dimethylformamide, stirring at a uniform speed, adding cuprous iodide and N,N-dimethyl-1,2-ethylenediamine, mixing evenly, heating to 100°C, reacting for 24 hours under a nitrogen atmosphere to obtain a modified filler, controlling the amount ratio of grafted talc, 4,4'-dichlorobenzil and N,N-dimethylformamide to be 10g:5g:80mL, the weight ratio of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine to be 1:1, and the sum of the weight of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine to be 5% of the weight of grafted talc.

[0024] The antioxidant is antioxidant 1010 or antioxidant 168.

[0025] The nucleating agent is a long-chain linear saturated carboxylic acid sodium salt nucleating agent, and its model is HAV101.

[0026] Comparative Example 1: Compared with Example 1, this comparative example uses talcum powder instead of the modified filler, and the rest is the same as Example 1.

[0027] The properties of the polypropylene films prepared in Examples 1-3 and Comparative Example 1 were tested, and the results are shown in Table 1 below: The heat shrinkage is measured after heating at 120°C for 15 min; Table 1 It can be seen from Table 1 above that the polypropylene films prepared in Examples 1-3 of the present invention have excellent mechanical properties and heat resistance.

[0028] The polypropylene films prepared in Examples 1-4 and Comparative Example 1 were used in the preparation of capacitors. All testing tests were conducted under the premise of ensuring safety. The prepared capacitors were subjected to relevant performance tests, wherein the breakdown strength was tested using a program-controlled withstand voltage tester and the dielectric constant was tested using a radio frequency impedance material analyzer. The test results are shown in Table 2: Table 2 It can be seen from Table 2 above that the polypropylene film prepared by the present invention has higher electrical breakdown strength and is more suitable for the capacitor field.

[0029] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described 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 protection scope of the present invention.

Claims

1. A high voltage film for wind power capacitors, characterized in that: The invention comprises the following raw materials in parts by weight: 50-80 parts of polypropylene resin, 3-5 parts of modified filler, 0.2-0.5 parts of antioxidant, and 0.3-0.5 parts of nucleating agent; The modified filler is prepared by the following steps: Step S1, adding talcum powder to a 20% by mass sodium hydroxide aqueous solution, heating to 80-90° C., stirring at high speed and reacting for 6 hours, washing with deionized water after the reaction to obtain modified talcum powder, then adding the obtained modified talcum powder to a 75% by volume ethanol aqueous solution, adjusting the system pH to 4-5, adding KH570, heating to 50-65° C., stirring at a uniform speed and reacting for 4-6 hours, and cooling to room temperature after the reaction to obtain modified talcum powder; Step S2, adding the prepared modified talc and maleimide into ethyl acetate, ultrasonically dispersing and adding dibenzoyl peroxide, heating to 70-90° C., stirring at a constant speed and reacting for 1 hour, and obtaining grafted talc after the reaction is completed; Step S3, adding 4,4'-dichlorobenzil and grafted talc into N,N-dimethylformamide, stirring at a uniform speed, adding cuprous iodide and N,N-dimethyl-1,2-ethylenediamine, mixing evenly, heating to 100°C, reacting under nitrogen atmosphere for 24 hours, to obtain a modified filler.

2. The high voltage-resistant film for wind power capacitor according to claim 1, characterized in that: The antioxidant is antioxidant 1010 or antioxidant 168.

3. The high voltage-resistant film for wind power capacitor according to claim 1, characterized in that: The nucleating agent is a long-chain linear saturated carboxylic acid sodium salt nucleating agent.

4. The high voltage-resistant film for wind power capacitor according to claim 1, characterized in that: In step S1, the dosage ratio of talcum powder and sodium hydroxide aqueous solution is controlled to be 5-10 g: 150-250 mL, and the dosage ratio of modified talcum powder, KH570 and ethanol aqueous solution is controlled to be 5-10 g: 1-2 g: 100 mL.

5. The high voltage-resistant film for wind power capacitor according to claim 1, characterized in that: In step S2, the dosage ratio of modified talc powder, maleimide and ethyl acetate is controlled to be 5-10 g: 2-3 g: 100 mL.

6. The high voltage-resistant film for wind power capacitor according to claim 1, characterized in that: In step S3, the amount ratio of grafted talc, 4,4'-dichlorobenzil and N,N-dimethylformamide is controlled to be 5-10g:3-5g:50-80mL, the weight ratio of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine is 1:1, and the sum of the weights of cuprous iodide and N,N-dimethyl-1,2-ethylenediamine is 3-5% of the weight of grafted talc.

7. The method for preparing a high-voltage film for wind power capacitors according to claim 1, characterized in that: The steps include: The raw materials are mixed uniformly, melted at 170-190° C., filtered and vented 10-12 times, hot-pressed at 20 MPa to form a thick sheet, stretched, and made into a film to obtain a high-voltage film for wind power capacitors.

8. The method for preparing a high-voltage film for wind power capacitors according to claim 7, characterized in that: The exhaust should be controlled every 8-10 seconds.

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