Ultrafine low-loss electronic fiber as well as preparation method and application thereof

Abstract

The invention relates to the field of electrical paper raw materials, and discloses a superfine low-loss electronic fiber as well as a preparation method and application thereof. According to the invention, the fiber raw material is prepared by the preparation method aiming at the gossypium hirsutum, and the fiber width of the fiber raw material is finer than that of common sisal hemp pulp fiber, Manila hemp pulp fiber and Chinese alpine rush pulp fiber, the strength is higher, the liquid absorption property is better, and the loss of the electrolytic capacitor diaphragm is more favorably reduced; after cooking, acid and ultrasonic waves are adopted to treat the slurry in a synergetic mode, dissolution of metal impurities in the slurry can be greatly increased, then the dissolved impurities are fixed through a metal chelating agent, readsorption is prevented, and the content of the metal impurities in the slurry can be effectively reduced after washing. The fiber prepared by the method is superfine, low in loss, high in strength and high in liquid absorbency, and is not only suitable for manufacturing a low-voltage electrolytic capacitor diaphragm, but also suitable for manufacturing a high-voltage electrolytic capacitor diaphragm.

Description

Technical Field

[0001] The present invention relates to the field of raw materials for electrical paper, and specifically to an ultrafine low-loss electronic fiber, a preparation method thereof, and an application thereof. Background Art

[0002] Electrical paper is required to have excellent chemical purity, high breakdown voltage resistance, low impedance, and good liquid absorption performance. Especially for electrolytic capacitor diaphragms, higher requirements are imposed on these properties. Currently, the raw materials used for electrolytic capacitor diaphragms include electronic-grade wood pulp fibers (coniferous wood pulp, broad-leaved wood pulp), electronic-grade non-wood pulp fibers (Chinese alpine rush pulp, Achnatherum splendens pulp, sisal pulp, Manila hemp pulp, abaca pulp, hemp pulp, flax pulp, kenaf pulp, pineapple leaf pulp, sandalwood bark pulp, wild cotton bark pulp, Spanish grass pulp, etc.), chemically modified plant fibers (such as dissolving pulp, Tencel fiber, viscose fiber, nanocellulose fiber, etc.), and chemical fibers (aramid fiber, glass fiber, polyethylene fiber, polypropylene fiber, polyester fiber, acetate fiber, spandex fiber, etc.).

[0003] Currently, all fiber raw materials used for preparing electrolytic capacitor diaphragms have some disadvantages: Electronic-grade wood pulp fibers are relatively wide, generally in the range of 10 µm to 60 µm. The paper made from them has good tensile strength, but its absorbency (water absorption and electrolyte absorption ability) is average and the loss is high (D value and S value of ESR); Electronic-grade non-wood pulp fibers and regenerated cellulose fibers have better absorbency and lower impedance, but the tensile strength of the formed paper is low; The paper made from chemical fibers has poor tensile strength and the lowest liquid absorption of the formed paper, and generally cannot be used alone to prepare electrolytic capacitor diaphragms.

[0004] Patent CN202210059914.X, "A Low-Impedance, High-Absorbency Insulating Wood Pulp and Preparation Method Thereof and Use in Electrical Paper", discloses a preparation method of a low-impedance, high-absorbency insulating wood pulp. The width of the wood pulp fibers is relatively wide, and it is only suitable for preparing high-voltage electrolytic capacitor diaphragms. There is a problem of relatively high loss when used to prepare low-voltage electrolytic capacitor diaphragms. CN202210277995.0, "An Insulating Pulp and Preparation Method Thereof", the insulating pulp is prepared from bamboo pulp as the raw material. However, the tensile strength of bamboo pulp is lower than that of hemp pulp and the fiber width is higher than that of hemp pulp. There are disadvantages of relatively high loss when using it to prepare electrolytic capacitor diaphragms. Patent CN202311818679.0, "A Low-Voltage Low-Loss Electrolytic Capacitor Diaphragm and Preparation Method Thereof", this method uses hemp pulp fibers and protein fibers for mixed papermaking, and adds protein fibers to reduce the loss of the diaphragm. However, the surface of protein fibers lacks hydrophilic functional groups and the fiber diameter binding force is poor, which will lead to a decrease in the strength of the diaphragm.

[0005] For the fiber raw materials used in electrolytic capacitor diaphragms, the smaller the fiber diameter, the shorter the ion movement distance and the lower the loss. For the above-mentioned fiber raw materials, wood pulp fibers have a relatively wide width and high loss; Tencel and viscose fibers are expensive and rely on imports, and the bonding force between fibers is poor, resulting in low strength of the produced diaphragms; pineapple pulp, Chinese alpine rush pulp, and achnatherum splendens pulp fibers have low strength, and the produced diaphragms have low tensile strength; sisal pulp and manila hemp pulp have relatively high strength, but the fibers are wider than grass pulp and have higher loss than grass pulp; chemical fibers are difficult to be realized on a general paper machine due to poor bonding strength of the formed paper. At the same time, the above-mentioned fibers all have the problem of relatively wide width. When using these fiber raw materials to prepare electrolytic capacitor diaphragms, it is difficult to further reduce the loss of the diaphragms.

[0006] Therefore, for the fiber raw materials used in electrolytic capacitor diaphragms, it is necessary to have relatively high strength, small width, and good liquid absorption performance. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides an ultra-fine low-loss electronic fiber and its application. The ultra-fine low-loss electronic fiber is mainly made of mountain cotton bark fiber. After specific mechanical and chemical treatments, fibers with excellent electrical and mechanical properties are formed, which are suitable for the diaphragm material of electrolytic capacitors. It can effectively reduce the energy loss of electrolytic capacitors and improve their high-frequency and high-voltage working stability. At the same time, the natural plant fiber materials used have good degradability, meet the requirements of modern environmental protection, and solve the environmental problems existing in traditional synthetic fiber materials. By improving the fiber treatment process, while maintaining the excellent mechanical properties of the fiber, its electrical properties can be greatly improved, significantly improving the efficiency and service life of electrolytic capacitors.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing an ultra-fine low-loss electronic fiber, the electronic fiber is prepared from mountain cotton bark, and the preparation method of the fiber includes the following steps: 1) Remove the surface impurities of the mountain cotton bark, dry it in the sun, and then cut it into lengths of 3 cm - 10 cm to obtain pulping raw materials; 2) Mix the pulping raw materials evenly with the cooking liquor, react at room temperature for 1 h - 3 h, then heat up to 120 - 130 °C within 10 min - 60 min, and keep warm for 10 min - 30 min; then heat up to 140 - 150 °C within 10 min - 30 min, and keep warm for 10 min - 30 min; then heat up to 160 - 170 °C within 10 min - 30 min, and keep warm for 1 h - 4 h; the cooking liquor is a mixture of sodium hydroxide, sodium silicate, sodium sulfide, and water; 3) Wash the obtained pulp with deionized water until the pH is 7 - 8 to obtain pulp A; 4) Disperse slurry A in water with a dispersion concentration of 2% - 5% for slurry A. Turn on the stirrer and adjust the pH to 2 - 5 with a sulfuric acid solution under stirring conditions. Treat it for 3 h - 5 h under the synergistic effect of ultrasonic waves, then turn off the ultrasonic waves, adjust the pH to 3 - 6 with ammonia water, then add a metal complexing agent, continue stirring for 1 h - 3 h, and then wash with deionized water until the pH is 6 - 7 to obtain electronic fibers, and the fibers have a fiber width of less than 10 µm.

[0009] Preferably, the weight ratio of sodium hydroxide : sodium silicate : sodium sulfide : water in the cooking liquor is (10 - 20) : (6 - 12) : (0.5 - 2) : (66 - 84).

[0010] Preferably, in step 2), the weight ratio of the pulping raw material to the cooking liquor is 1 : (4 - 10).

[0011] Preferably, in step 4), the ultrasonic frequency is 40 kHz - 100 kHz and the power is 20 W / m³ - 1000 W / m³.

[0012] Preferably, in step 4), the metal chelating agent is one or more of ethylenediaminetetraacetic acid, ammonium ethylenediaminetetraacetate, citric acid, nitrilotriacetic acid, glycolic acid, and polyacrylic acid.

[0013] Preferably, in step 4), the dosage of the metal chelating agent is 0.5% - 5% of the absolute dry weight of slurry A.

[0014] Preferably, in step 4), the concentration of the sulfuric acid solution is 0.8 - 1.5 M.

[0015] Furthermore, the present invention also provides the ultrafine low-loss electronic fibers obtained by the described preparation method.

[0016] Furthermore, the present invention also provides the application of the ultrafine low-loss electronic fibers in the preparation of electrolytic capacitor diaphragms, making it suitable for reducing the electrolyte loss in electrolytic capacitor diaphragms, thereby improving the performance of the capacitor.

[0017] Furthermore, the present invention also provides an electrolytic capacitor diaphragm, and the fibers of the electrolytic capacitor diaphragm include the ultrafine low-loss electronic fibers.

[0018] The present invention prepares a fiber raw material by a preparation method for Diplomorpha sikokiana. Its fiber width is finer, its strength is higher, and its liquid absorption property is better than those of commonly used sisal pulp fibers, Manila hemp pulp fibers, and Chinese alpine rush pulp fibers, which is more conducive to reducing the loss of electrolytic capacitor diaphragms. Immediately after cooking, the pulp is treated with acid and ultrasonic waves in combination, which can greatly increase the dissolution of metal impurities in the pulp. Then, a metal chelating agent is used to fix the dissolved impurities to prevent re-adsorption. After washing, the metal impurity content in the pulp can be effectively reduced. The fibers prepared by this method are superfine, low-loss, high-strength, and high-liquid-absorbing, and are applicable not only to the papermaking of low-voltage electrolytic capacitor diaphragms but also to the papermaking of high-voltage electrolytic capacitor diaphragms. The specific manifestations are as follows: 1. Reducing the loss of electrolytic capacitor diaphragms: By using Diplomorpha sikokiana as a raw material to prepare superfine and low-loss electronic fibers, the present invention can significantly reduce the electrolyte loss in electrolytic capacitor diaphragms. Since the fiber width is less than 10 µm, it has excellent liquid absorption performance and high strength, which can effectively improve the performance of electrolytic capacitors, especially during long-term use, reducing the self-discharge rate of capacitors and improving energy efficiency.

[0019] 2. Improving the mechanical strength and liquid absorption capacity of capacitor diaphragms: The electronic fibers prepared by the present invention not only have good mechanical properties but also have strong liquid absorption capacity, can maintain a stable structure under the long-term action of the electrolyte, reduce the evaporation and loss of the electrolyte, and thus extend the service life of electrolytic capacitors.

[0020] 3. Green and environmentally friendly preparation process: The present invention uses Diplomorpha sikokiana as a raw material and utilizes the environmentally friendly cooking liquor and ultrasonic wave combined treatment technology, without the use of a large amount of harmful chemicals. The preparation process is green and environmentally friendly, meeting the increasingly strict environmental protection requirements.

[0021] 4. Improving the overall performance of electrolytic capacitors: Due to the superfine characteristics of the electronic fibers, they can better meet the requirements of electrolytic capacitor diaphragms, improve the dielectric properties of capacitors, and thus improve the overall performance of electrolytic capacitors. Especially under extreme conditions such as high frequency and high temperature, they can still maintain low loss and good performance.

[0022] 5. Remarkable energy-saving and consumption-reducing effects: The electrolytic capacitors manufactured with the electronic fibers of the present invention can effectively reduce the loss of the electrolyte, thereby reducing energy consumption, improving the working efficiency of the capacitors, having remarkable energy-saving effects, and playing a positive role in improving the energy efficiency of the overall equipment. The superfine and low-loss electronic fibers provided by the present invention have broad application prospects, can promote the development of new capacitor materials, and provide material support for the high performance and high reliability of the next generation of electrolytic capacitors. Especially in the fields of new energy, electronic equipment, and power electronics, they have important practical application values. Description of the Drawings

[0023] Figure 1 It is a figure of the fiber optic microscope (100 times) of Example 1.

[0024] Figure 2 It is a figure of the fiber optic microscope (100 times) of Comparative Example 1.

[0025] Figure 3 It is a figure of the fiber optic microscope (100 times) of Comparative Example 2.

[0026] Figure 4 It is a figure of the fiber optic microscope (100 times) of Comparative Example 3.

[0027] Figure 5 It is a figure of the fiber optic microscope (100 times) of Comparative Example 5. Detailed implementation manners

[0028] Combined with the embodiments of the present invention below, the technical solutions in the embodiments will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0029] Example 1 After removing the surface impurities of the bark of Broussonetia papyrifera, it is dried in the sun and cut into lengths of 5 cm to obtain the pulping raw material, which is then mixed evenly with the cooking liquor. The ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquor is 15:8:1:76, and the weight ratio of the pulping raw material to the cooking liquor is 1:5. The reaction is carried out at room temperature for 2 h, then heated to 125 °C in 30 min and kept warm for 20 min; then heated to 145 °C in 20 min and kept warm for 20 min; then heated to 165 °C in 20 min and kept warm for 2 h. After the heat preservation is completed, the exhaust gas is discharged, and the obtained product is washed with deionized water until the pH is 7 ± 0.1 to obtain the pulp. Then the pulp is dispersed in water, and the dispersion concentration of the pulp is 3%. The stirrer is started, and the pH is adjusted to 3 with a 1 M sulfuric acid solution under stirring conditions and treated for 4 h under the synergistic effect of ultrasonic waves. Then the ultrasonic wave is turned off, and the pH is adjusted to 4 with ammonia water. Then citric acid is added, and the dosage of citric acid is 1% of the absolute dry weight of the pulp. Stirring is continued for 2 h, and then it is washed with deionized water until the pH is 6.5 ± 0.1 to obtain an ultra-fine, low-loss, high-strength, and high-liquid-absorbing electronic fiber material. Then the fiber is beaten and made into paper by a cylinder mould machine, and the detection indexes are measured.

[0030] Example 2 After removing the surface impurities, dry the bark of Diospyros kaki Thunb. var. sylvestris Makino in the sun and cut it into pieces with a length of 5 cm. Then mix it evenly with the cooking liquor. The ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquor is 15:8:1:76. The weight ratio of the pulping raw material to the cooking liquor is 1:5. React at room temperature for 2 h, then heat up to 125 °C in 30 min and keep the temperature for 20 min; then heat up to 145 °C in 20 min and keep the temperature for 20 min; then heat up to 165 °C in 20 min and keep the temperature for 2 h. After the heat preservation is completed, exhaust the gas. Wash the obtained product with deionized water until the pH is 7±0.1 to obtain pulp. Then disperse the pulp in water, and the dispersion concentration of the pulp is 3%. Turn on the stirrer and adjust the pH to 2.5 with 1 M sulfuric acid solution under stirring conditions. Treat it for 4 h under the synergistic effect of ultrasonic waves. Then turn off the ultrasonic wave, adjust the pH to 4 with ammonia water, then add citric acid, and the dosage of citric acid is 1% of the absolute dry weight of the pulp. Continue stirring for 2 h, and then wash it with deionized water until the pH is 6.5±0.1 to obtain an ultra-fine, low-loss, high-strength, and high-liquid-absorbing electronic fiber material. Then, after the fiber is defibrated, cylinder screen papermaking is adopted to detect the indexes.

[0031] Example 3 After removing the surface impurities, dry the bark of Diospyros kaki Thunb. var. sylvestris Makino in the sun and cut it into pieces with a length of 5 cm. Then mix it evenly with the cooking liquor. The ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquor is 15:8:1:76. The weight ratio of the pulping raw material to the cooking liquor is 1:5. React at room temperature for 2 h, then heat up to 125 °C in 30 min and keep the temperature for 20 min; then heat up to 145 °C in 20 min and keep the temperature for 20 min; then heat up to 165 °C in 20 min and keep the temperature for 2 h. After the heat preservation is completed, exhaust the gas. Wash the obtained product with deionized water until the pH is 7±0.1 to obtain pulp. Then disperse the pulp in water, and the dispersion concentration of the pulp is 3%. Turn on the stirrer and adjust the pH to 2.5 with 1 M sulfuric acid solution under stirring conditions. Treat it for 4 h under the synergistic effect of ultrasonic waves. Then turn off the ultrasonic wave, adjust the pH to 4 with ammonia water, then add citric acid, and the dosage of citric acid is 2% of the absolute dry weight of the pulp. Continue stirring for 2 h, and then wash it with deionized water until the pH is 6.5±0.1 to obtain an ultra-fine, low-loss, high-strength, and high-liquid-absorbing electronic fiber material. Then, after the fiber is defibrated, cylinder screen papermaking is adopted to detect the indexes.

[0032] Comparative Example 1 Dry the sisal and cut it into lengths of 5 cm, then mix it evenly with the cooking liquor. The ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquor is 15:8:1:76. The weight ratio of the pulping raw material to the cooking liquor is 1:5. React at room temperature for 2 h, then raise the temperature to 125 °C in 30 min and hold for 20 min; then raise the temperature to 145 °C in 20 min and hold for 20 min; then raise the temperature to 165 °C in 20 min and hold for 2 h. After the holding is completed, exhaust the gas, wash the obtained pulp with deionized water until the pH is 7 ± 0.1 to obtain the pulp. Then disperse the pulp in water, and the pulp dispersion concentration is 3%. Turn on the stirrer and adjust the pH to 3 with 1 M sulfuric acid solution under stirring conditions, and treat it under the synergistic action of ultrasonic waves for 4 h. Then turn off the ultrasonic waves, adjust the pH to 4 with ammonia water, then add citric acid, and the dosage of citric acid is 1% of the absolute dry weight of the pulp. Continue to stir for 2 h, and then wash with deionized water until the pH is 6.5 ± 0.1 to obtain the electronic fiber material. Then defiber the fiber and use a cylinder mold to make paper and detect the indexes.

[0033] Comparative Example 2 Dry the manila hemp and cut it into lengths of 5 cm, then mix it evenly with the cooking liquor. The ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquor is 15:8:1:76. The weight ratio of the pulping raw material to the cooking liquor is 1:5. React at room temperature for 2 h, then raise the temperature to 125 °C in 30 min and hold for 20 min; then raise the temperature to 145 °C in 20 min and hold for 20 min; then raise the temperature to 165 °C in 20 min and hold for 2 h. After the holding is completed, exhaust the gas, wash the obtained pulp with deionized water until the pH is 7 ± 0.1 to obtain the pulp. Then disperse the pulp in water, and the pulp dispersion concentration is 3%. Turn on the stirrer and adjust the pH to 3 with 1 M sulfuric acid solution under stirring conditions, and treat it under the synergistic action of ultrasonic waves for 4 h. Then turn off the ultrasonic waves, adjust the pH to 4 with ammonia water, then add citric acid, and the dosage of citric acid is 1% of the absolute dry weight of the pulp. Continue to stir for 2 h, and then wash with deionized water until the pH is 6.5 ± 0.1 to obtain the electronic fiber material. Then defiber the fiber and use a cylinder mold to make paper and detect the indexes.

[0034] Comparative Example 3 Dry the pogonatherum crinitum and cut it into pieces with a length of 5 cm, then mix it evenly with the cooking liquor. The ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquor is 15:8:1:76. The weight ratio of the pulping raw material to the cooking liquor is 1:5. React at room temperature for 2 h, then heat it to 125 °C in 30 min and keep it warm for 20 min; then heat it to 145 °C in 20 min and keep it warm for 20 min; then heat it to 165 °C in 20 min and keep it warm for 2 h. After the heat preservation is completed, exhaust the gas, wash the obtained pulp with deionized water until the pH is 7±0.1 to obtain the pulp. Then disperse the pulp in water, and the dispersion concentration of the pulp is 3%. Turn on the stirrer and adjust the pH to 3 with 1 M sulfuric acid solution under stirring conditions, and treat it for 4 h under the synergistic effect of ultrasonic waves. Then turn off the ultrasonic wave, adjust the pH to 4 with ammonia water, then add citric acid, and the dosage of citric acid is 1% of the absolute dry weight of the pulp. Continue to stir for 2 h, and then wash it with deionized water until the pH is 6.5±0.1 to obtain the electronic fiber material. Then beat the fiber and use a cylinder mold to make paper, and detect the indexes.

[0035] Comparative Example 4 Remove the surface impurities of the eriolaena spectabilis, dry it, and cut it into pieces with a length of 5 cm to obtain the pulping raw material. Then mix it evenly with the cooking liquor. The ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquor is 15:8:1:76. The weight ratio of the pulping raw material to the cooking liquor is 1:5. React at room temperature for 2 h, then heat it to 125 °C in 30 min and keep it warm for 20 min; then heat it to 145 °C in 20 min and keep it warm for 20 min; then heat it to 165 °C in 20 min and keep it warm for 2 h. After the heat preservation is completed, exhaust the gas, wash the obtained product with deionized water until the pH is 7±0.1 to obtain the pulp. Then disperse the pulp in water, and the dispersion concentration of the pulp is 3%. Turn on the stirrer and adjust the pH to 3 with 1 M sulfuric acid solution under stirring conditions. After treating for 4 h, adjust the pH to 4 with ammonia water, then add citric acid, and the dosage of citric acid is 1% of the absolute dry weight of the pulp. Continue to stir for 2 h, and then wash it with deionized water until the pH is 6.5±0.1 to obtain the electronic fiber material. Then beat the fiber and use a cylinder mold to make paper, and detect the indexes.

[0036] Comparative Example 5 This comparative example is Example 6 of the invention patent CN202210277995.0.

[0037] All kinds of raw materials, reagents, instruments and equipment used in the present invention can be obtained through market purchase or can be prepared by existing methods. The detection methods are as follows: Bulk density: GB / T 451.3; Thickness: GB / T 451.3; Tensile strength: GB / T 12914; Water absorption height: GB / T 461.1; Air permeability: GB / T 23227; Internal resistance: Prepare the separator into a capacitor and measure it using an LCR meter at a temperature of 20°C and a frequency of 1 kHz. Ash content: GB / T 742; Fiber width: Measure it using an optical microscope (100 times magnification).

[0038] The test results of the above-mentioned examples and comparative examples are shown in the following table.

[0039] The above is the description of the embodiments of the present invention. Through the above description of the disclosed embodiments, those skilled in the art can implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel points disclosed herein.

Claims

1. A method for preparing ultrafine low-loss electronic fibers, characterized in that: The electronic fiber is prepared from mountain cotton peel; the preparation method of the fiber comprises the following steps: 1) Remove impurities from the surface of the mountain cotton bark, dry it in the sun, and then cut it into 3cm-10cm lengths to obtain pulping raw materials; 2) Mix the pulping raw material and the cooking liquid evenly, react at room temperature for 1h-3h, then heat to 120-130°C within 10min-60min, and keep warm for 10min-30min; then heat to 140-150°C within 10min-30min, and keep warm for 10min-30min; then heat to 160-170°C within 10min-30min, and keep warm for 1h-4h; the cooking liquid is a mixture of sodium hydroxide, sodium silicate, sodium sulfide and water; 3) washing the obtained slurry with deionized water until the pH value is 7-8 to obtain slurry A; 4) Dispersing slurry A in water, the dispersion concentration of slurry A is 2%-5%, turning on the stirrer, adjusting the pH to 2-5 with sulfuric acid solution under stirring conditions, treating for 3h-5h under ultrasonic synergy, then turning off the ultrasonic wave, adjusting the pH to 3-6 with ammonia water, then adding a metal chelating agent, continuing to stir for 1h-3h, and then washing with deionized water to a pH of 6-7 to obtain electronic fibers, wherein the fibers have a fiber width of less than 10µm.

2. The preparation method according to claim 1, characterized in that: The weight ratio of sodium hydroxide: sodium silicate: sodium sulfide: water in the cooking liquid is (10-20): (6-12): (0.5-2): (66-84).

3. The preparation method according to claim 1, characterized in that: In step 2), the weight ratio of pulping raw material to cooking liquid is 1:(4-10).

4. The preparation method according to claim 1, characterized in that: In step 4), the ultrasonic frequency is 40kHz-100kHz and the power is 20W / m 3 -1000W / m 3 .

5. The preparation method according to claim 1, characterized in that: In step 4), the metal chelating agent is one or more of ethylenediaminetetraacetic acid, ammonium ethylenediaminetetraacetate, citric acid, aminotriacetic acid, glycolic acid, and polyacrylic acid.

6. The preparation method according to claim 1, characterized in that: In step 4), the amount of the metal chelating agent used is 0.5%-5% of the absolute dry weight of the slurry.

7. The preparation method according to claim 1, characterized in that: In step 4), the concentration of the sulfuric acid solution is 0.8-1.5M.

8. An ultrafine low-loss electronic fiber obtained by the preparation method according to any one of claims 1 to 7.

9. The use of the ultrafine low-loss electronic fiber according to claim 8 in the preparation of electrolytic capacitor diaphragms makes it suitable for reducing the electrolyte loss in the electrolytic capacitor diaphragms, thereby improving the performance of the capacitor.

10. An electrolytic capacitor diaphragm, characterized in that: The fibers of the electrolytic capacitor diaphragm include the ultrafine low-loss electronic fibers according to claim 8.

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