High-pressure-resistant and low-explosion-rate electrolytic capacitor paper and production process thereof

Abstract

The application relates to the technical field of papermaking, and particularly provides high-pressure-resistance low-explosion-rate electrolytic capacitor paper and a production process thereof; the electrolytic capacitor paper comprises the following components: polyethylene terephthalate microfiber 30-50%, modified cellulose short fiber 20-40%, aluminum silicate nanoparticles 5-15%, silane coupling agent 0.5-1.5%, and wet-strength resin 10-25%. The polyethylene terephthalate microfiber is used to construct a high-strength skeleton, the modified cellulose short fiber is used to strengthen the fiber-inorganic interface, the aluminum silicate nanoparticles are used to precisely fill pores, the silane coupling agent is used to enhance the multiphase combination, the wet-strength resin is used to maintain fiber adhesion in a wet state, and the layered gradient pore design is used, so that excellent compression strength and uniform electrolyte immersion are realized, local over-immersion and bubble aggregation are effectively inhibited, the risk of breakdown and explosion is significantly reduced, and the safety and reliability of the capacitor paper under high-pressure long-life working conditions are improved.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology. Specifically, this invention provides a high-compression-strength, low-explosion-rate electrolytic capacitor paper and its production process. Background Technology

[0002] Existing electrolytic capacitor paper mostly uses pure cellulose or cellulose / inorganic filler composite systems. Although the dielectric and impregnation properties meet the requirements, fiber breakage can easily occur under high voltage and long-life conditions, leading to dielectric breakdown and explosive failure. In addition, to improve compressive strength, the paper thickness or pulp content is usually increased, but this reduces the penetration rate of the conductive liquid, affecting the capacitor performance. Summary of the Invention

[0003] This invention provides a high-compression-strength, low-explosion-rate electrolytic capacitor paper and its manufacturing process. By constructing a high-strength skeleton from polyethylene terephthalate microfibers, reinforcing the fiber-inorganic interface with modified cellulose short fibers, precisely filling the pores with aluminum silicate nanoparticles, enhancing the multi-component structure with silane coupling agents, and maintaining fiber bonding with wet-strength resin in a wet state, combined with a layered gradient pore design, it achieves excellent compressive strength and uniform electrolyte impregnation, effectively suppressing local over-impregnation and bubble aggregation, significantly reducing the risk of breakdown and explosion, and improving the safety and reliability of the capacitor paper under high-voltage, long-life operating conditions.

[0004] This invention provides a high-compression-strength, low-explosion-rate electrolytic capacitor paper, comprising the following components by weight percentage and totaling 100%: polyethylene terephthalate microfibers: 30-50%, modified cellulose short fibers: 20-40%, aluminum silicate nanoparticles: 5-15%, silane coupling agent: 0.5-1.5%, and wet-strength resin: 10-25%.

[0005] In any of the above technical solutions, the electrolytic capacitor paper has a layered gradient pore structure, and the electrolytic capacitor paper includes a surface region and a core region; wherein, the pore size of the surface region is 0.5~2μm, and the pore size of the core region is 5~10μm.

[0006] In any of the above technical solutions, the diameter of the polyethylene terephthalate microfibers is 5~10μm and the length is 1~2mm.

[0007] In any of the above technical solutions, the modified cellulose short fibers are pretreated softwood pulp with a freeness of 40~50°SR and a length of 0.8~1.2mm.

[0008] This invention provides a production process for high-compression-strength, low-explosion-rate electrolytic capacitor paper, comprising the following steps: S100, adding polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles, and silane coupling agent to water, mixing and dispersing to form a first slurry; S200, sequentially applying a double-wire forming method, directional impregnation, and wet stretching to obtain a wet paper blank; S300, impregnating the wet paper blank with glutaraldehyde for chemical cross-linking to obtain electrolytic capacitor paper.

[0009] In any of the above technical solutions, the preparation method of modified cellulose short fibers in step S100 is as follows: S110, sodium hydroxide solution is added to the cellulose short fiber slurry. After the reaction is completed, it is washed with deionized water until neutral and then separated into solid and liquid to obtain a fiber suspension; S111, methacryloyloxypropyltriethoxysilane is added to the fiber suspension, stirred, and then washed with deionized water until neutral to obtain modified cellulose short fibers.

[0010] In any of the above technical solutions, in step S110, the concentration of sodium hydroxide solution is 10~20 wt.%, the reaction temperature is 50~80℃, and the reaction time is 30~60 min; in step S111, the amount of methacryloyloxypropyltriethoxysilane is 0.5~0.6 wt.%, the stirring time is 10~15 h, and the stirring speed is 200~500 rpm.

[0011] In any of the above technical solutions, step S200 specifically includes: S201, using a double-mesh forming method with a surface mesh of 180-220 mesh and a core mesh of 40-80 mesh to form the first pulp to obtain a first wet paper blank; S202, immersing the first wet paper blank in a 5-10 wt.% first wet strength resin solution, dehydrating it, and then immersing it again in a 15-20 wt.% second wet strength resin solution for directional immersion to obtain a second wet paper blank; S203, stretching the second wet paper blank in the longitudinal direction by 12-18% at a speed of 1-5 m / min to obtain a wet paper blank.

[0012] In any of the above technical solutions, in step S202, the first wet-strength resin solution includes a polyamide-polyamine-epoxychlorohydrin resin solution or a melamine-formaldehyde resin solution; the second wet-strength resin solution includes a polyamide-polyamine-epoxychlorohydrin resin solution or a melamine-formaldehyde resin solution.

[0013] In any of the above technical solutions, step S300 specifically includes: S301, impregnating the wet paper blank with glutaraldehyde solution to carry out a chemical cross-linking reaction to obtain a cross-linked wet paper blank; S302, placing the cross-linked wet paper blank in a vacuum dehydration device and treating it under a vacuum pressure of 50~80kPa for 1~2min to obtain a paper blank; S303, drying the paper blank at 80~120℃ for 2~4h to obtain electrolytic capacitor paper.

[0014] The technical effects that can be achieved by adopting the technical solution of the present invention are as follows:

[0015] 1. Through the high-strength skeleton structure of polyethylene terephthalate microfibers and modified cellulose short fibers, and the bonding and reinforcement of fibers by wet-strength resin in a wet state, the electrolytic capacitor paper of the present invention can effectively disperse concentrated stress under high voltage load, significantly improve compressive and tear resistance, avoid dielectric breakdown caused by fiber rupture, and provide a solid mechanical guarantee for safe and reliable operation under long-term high voltage conditions.

[0016] 2. The molecular-level "bridge" built by the silane coupling agent between the fiber and the aluminum silicate nanoparticles, and the three-dimensional network formed by the chemical cross-linking of glutaraldehyde, enable the capacitor paper to exhibit excellent interfacial bonding strength and dimensional stability in both wet and dry states. It can resist the erosion of high humidity, high temperature and electrolyte environment, and significantly improve aging resistance and service life.

[0017] 3. By combining a layered gradient pore design with precise nanofilling, the dense micropores on the surface layer prevent excessive wetting, while the large pores in the core layer retain permeable channels. Combined with a two-stage directional impregnation and wet stretching process, this not only achieves uniform impregnation and rapid conduction of the electrolyte, but also effectively suppresses bubble aggregation, significantly improves the breakdown voltage, and reduces the equivalent series resistance, thereby greatly reducing the explosion failure rate and optimizing the overall electrical performance of the capacitor. Attached Figure Description Detailed Implementation

[0018] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0019] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0020] To make the above-mentioned objectives, features and advantages of this aspect more apparent and understandable, specific embodiments of this aspect are described in detail below.

[0021] Existing electrolytic capacitor paper mostly uses pure cellulose or cellulose / inorganic filler composite systems. Although the dielectric and impregnation properties meet the requirements, fiber breakage can easily occur under high voltage and long-life conditions, leading to dielectric breakdown and explosive failure. In addition, to improve compressive strength, the paper thickness or pulp content is usually increased, but this reduces the penetration rate of the conductive liquid, affecting the capacitor performance.

[0022] To overcome the shortcomings of existing technologies, this embodiment provides a high-compressive-strength, low-explosion-rate electrolytic capacitor paper. This paper achieves superior compressive strength and uniform electrolyte impregnation by combining polyethylene terephthalate microfibers to construct a high-strength skeleton, modified cellulose short fibers to reinforce the fiber-inorganic interface, aluminosilicate nanoparticles to precisely fill the pores, silane coupling agents to enhance the composite structure, and wet-strength resin to maintain fiber adhesion in a wet state. This, along with a layered gradient pore design, effectively suppresses localized over-impregnation and bubble aggregation, significantly reducing the risk of breakdown and explosion, and improving the safety and reliability of the capacitor paper under high-voltage, long-life operating conditions.

[0023] Preferably, the electrolytic capacitor paper comprises the following components: polyethylene terephthalate microfibers: 30-50%, modified cellulose short fibers: 20-40%, aluminum silicate nanoparticles: 5-15%, silane coupling agent: 0.5-1.5%, and wet-strength resin: 10-25%. Through the synergistic effect of multiple components, significant improvements have been achieved in structural strength, electrolyte management, and long-term reliability. Polyethylene terephthalate microfibers form a high-strength skeleton in the paper matrix, providing excellent compressive and tear resistance and effectively dispersing stress under high pressure. Modified cellulose short fibers form stable chemical bonds at the fiber-inorganic particle interface, enhancing the adhesion between phases, allowing the nanofiller and fiber network to maintain structural integrity under high humidity and high temperature environments. Aluminum silicate nanoparticles precisely fill the paper pores, not only inhibiting local over-wetting of electrolyte through physical barriers but also adjusting the pore size distribution, dissipating local electric field concentration, and reducing the probability of dielectric breakdown. Silane coupling agents build a molecular-level "bridge" between inorganic particles and cellulose short fibers, further enhancing the interfacial bonding strength and aging resistance of the multiphase system. The wet-strength resin maintains high cohesion and fiber adhesion even in a wet state. Combined with a dual-gradient pore design, a dense barrier layer is formed on the paper surface while the core layer retains permeable channels, achieving uniform impregnation and rapid conduction of the electrolyte.

[0024] Preferably, the electrolytic capacitor paper has a layered gradient pore structure, comprising a surface region and a core region; wherein the pore size of the surface region is 0.5~2μm, and the pore size of the core region is 5~10μm; this layered gradient pore structure is achieved through a double-web forming and directional impregnation process. First, in the double-web forming stage, the surface web and the core web control the fiber deposition density respectively, so that the surface layer forms micropores of 0.5~2μm, and the core layer retains macropores of 5~10μm; subsequently, in the wet-strength resin directional impregnation and vacuum dehydration process, the low-solids content resin only fills the surface micropores, while the high-solids content resin penetrates into the core macropores, thereby forming a pore gradient of "dense surface and permeable core" within the same wet paper blank. The surface micropores and resin layer together form a highly efficient barrier layer, which can prevent excessive local wetting of electrolyte and bubble migration. The core layer macropores and their uniform interconnected channels ensure rapid and uniform penetration of electrolyte and ion migration, significantly improving breakdown voltage and reducing equivalent series resistance, while taking into account the air permeability and compressive strength of the paper, ultimately achieving low explosion rate and high reliability of capacitor paper.

[0025] Preferably, the polyethylene terephthalate (PET) microfibers have a diameter of 5–10 μm and a length of 1–2 mm, which helps to form a uniform, continuous, and interwoven three-dimensional fiber network in the paper matrix. The moderate fiber diameter ensures high filling density and network density at the microscale, thereby significantly enhancing the compressive and tear strength of the paper. The 1–2 mm fiber length balances the toughness and flexibility of the network, allowing for effective stress dispersion between fibers under high pressure loads and preventing fatigue fracture. In addition, the synergistic effect of PET microfibers and cellulose short fibers can optimize the pore structure, providing stable mechanical support for subsequent gradient impregnation and nanoparticle filling, ultimately improving the overall reliability and service life of the capacitor paper.

[0026] Preferably, the modified cellulose short fibers are pretreated softwood pulp with a freeness of 40-50°SR and a length of 0.8-1.2 mm, which can significantly optimize the fiber network and paper base properties: First, the medium freeness increases the degree of cellulose fibrillation on the fiber surface, improving the surface area and hydroxyl exposure, thereby enhancing the chemical and physical bonding with silane coupling agents and wet-strength resins; Second, the fiber length of 0.8-1.2 mm ensures sufficient inter-fiber cross-entanglement to form a high-toughness network structure, while also achieving uniform distribution in double-network forming, avoiding uneven porosity caused by excessive aggregation of short fibers or entanglement of long fibers; Finally, this modified short fiber works synergistically with polyethylene terephthalate microfibers and nano-aluminum silicate in the composite system, not only improving the cohesiveness and tear strength of the paper, but also helping to achieve gradient pore control and nanofilling through its good dispersibility and interfacial bonding properties, further reducing local electric field concentration, and improving the compressive strength, dielectric uniformity, and reliability of electrolytic capacitor paper.

[0027] Specifically, this embodiment provides a production process for high-compression-resistant, low-explosion-rate electrolytic capacitor paper, including the following steps:

[0028] S100. Polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles and silane coupling agent are added to water, mixed and dispersed to form a slurry, and the first slurry is obtained.

[0029] S200: The first pulp is sequentially subjected to double-wire forming, directional impregnation, and wet stretching to obtain a wet paper blank;

[0030] S300. The wet paper blank is impregnated with glutaraldehyde for chemical cross-linking to obtain electrolytic capacitor paper.

[0031] Preferably, the modified cellulose short fiber preparation method in step S100 is as follows: S110, sodium hydroxide solution is added to the cellulose short fiber slurry, and after the reaction is completed, it is washed with deionized water until neutral to perform solid-liquid separation and obtain fiber suspension; S111, methacryloyloxypropyltriethoxysilane is added to the fiber suspension, stirred, and then washed with deionized water until neutral to obtain modified cellulose short fiber. In step S110, adding sodium hydroxide to the cellulose short fiber slurry not only physically removes residual lignin and impurities from the fiber surface, but also causes cellulose to cellulose and undergo microscopic cleavage, significantly increasing the fiber surface area and hydroxyl exposure. This greatly enhances the compatibility and adhesion with subsequent resins and inorganic fillers. Meanwhile, silane coupling modification introduces organic functional groups onto the cellulose surface, enabling the formation of strong chemical bonds and physical adsorption between the fiber, aluminosilicate nanoparticles, and epoxy / polyamide wet-strength resin. This not only strengthens the bonding strength and aging resistance of the fiber-particle-resin interface in the multiphase system, but also effectively prevents fiber expansion and interface failure in a wet state, thereby ensuring the structural stability, tear resistance, and breakdown reliability of the final electrolytic capacitor paper under high humidity, high voltage, and long-life conditions.

[0032] Furthermore, in step S100, polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles, and silane coupling agents are thoroughly mixed and dispersed in water. This not only breaks up the agglomerates of fibers and nanoparticles, ensuring that each component is evenly distributed in the slurry and avoiding voids or uneven performance during molding, but also allows the silane coupling agent to be pre-adsorbed on the surface of fibers and particles, activating interfacial chemical activity and providing a strong bonding point for subsequent wet-strength resin impregnation and chemical crosslinking. At the same time, the stable slurry system ensures the fluidity and molding consistency in the double-network molding process, laying a solid foundation for the formation of a homogeneous and tough three-dimensional composite network within the final paper base.

[0033] Preferably, in step S200, firstly, a double-mesh forming process using a surface layer mesh of 180-220 mesh and a core layer mesh of 40-80 mesh is used to precisely construct a layered gradient pore structure of surface micropores and core macropores in the same wet paper blank. Subsequently, two-stage directional impregnation is used: firstly, 5-10 wt.% of a first wet-strength resin is used to pre-wet the surface layer and then pre-cured by vacuum dehydration; secondly, 15-20 wt.% of a second wet-strength resin is used to deeply fill the core macropores, thereby strengthening the surface barrier without affecting the unobstructed flow of the channels. Finally, the second wet paper blank is wet-stretched in the longitudinal direction at a draw ratio of 12-18% and a speed of 1-5 m / min, so that the fibers and resin molecules are oriented along the paper machine direction, further improving the compressive strength and toughness of the paper base, and forming a uniform resin film inside the pores, ultimately obtaining a high-performance wet paper blank that is both dense and transparent, crack-resistant, and has uniform liquid conductivity.

[0034] Furthermore, in step S202, the first wet-strength resin pre-impregnates the surface layer, forming a continuous, water-swellable cross-linked film on the fiber surface and within the micropores. This rapidly enhances the cohesive force between fibers, making the wet paper blank less prone to fiber slippage or structural collapse during subsequent dehydration and drying. The second wet-strength resin, with a higher solids content, penetrates deep into the macropores of the core layer, constructing a dense and elastic network resin skeleton. This not only further improves wet strength and compressive strength but also maintains long-term stable mechanical support and barrier effects in high-humidity or electrolyte environments. The combined impregnation of these two resins not only achieves the dual functions of "surface sealing and anti-permeability" and "core layer reinforcement and flow guidance" but also, through gradient control of cross-linking degree and penetration depth, enables the final paper base to possess excellent tear resistance, durability, and electrolyte management capabilities, thereby minimizing the risk of dielectric breakdown and explosion.

[0035] Preferably, in step S301, the wet paper blank is impregnated with glutaraldehyde solution to carry out a chemical cross-linking reaction, resulting in a cross-linked wet paper blank. Glutaraldehyde chemically cross-links with the amino groups on cellulose and wet-strength resin to form a three-dimensional cross-linked network, which significantly improves the dry and wet strength and dimensional stability of the paper base. In step S302, vacuum dehydration rapidly removes free water at 50~80 kPa to prevent the fiber skeleton and cross-linked structure from collapsing or deforming during dehydration, while also reducing the subsequent drying load. Finally, in step S303, the paper is dried at a constant temperature of 80~120℃ for 2~4 hours, which not only completely removes residual moisture but also completely solidifies the cross-linked network, locking the gradient pore structure and resin distribution, thereby obtaining an electrolytic capacitor paper with high compressive strength, good electrolyte management ability, and excellent aging resistance.

[0036] In summary, this embodiment achieves a significant increase in the compressive strength of electrolytic capacitor paper by leveraging the synergistic effects of polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles, silane coupling agents, and wet-strength resin, combined with a layered gradient pore structure design. This effectively disperses stress and prevents fiber breakage. The material interface is strengthened, exhibiting both wet and dry strength, and excellent aging resistance. The gradient pores and nanofillers construct uniform impregnation channels, improving electrolyte management efficiency and reducing local over-impregnation and bubble aggregation. Overall, the embodiment significantly improves breakdown voltage, reduces equivalent series resistance, and lowers explosion failure rate.

[0037] Example 1

[0038] This embodiment provides a high-compression-strength, low-explosion-rate electrolytic capacitor paper, which comprises the following components by weight percentage:

[0039] Polyethylene terephthalate microfibers with a diameter of 8μm and a length of 1.5mm: 40%, modified cellulose short fibers with a length of 1mm: 30%, aluminum silicate nanoparticles: 10%, silane coupling agent: 1%, wet-strength resin: 19%;

[0040] Its production process includes the following steps:

[0041] S110. Add a 15 wt.% sodium hydroxide solution to the cellulose short fiber slurry, react at 70°C for 45 min, wash with deionized water until neutral, and perform solid-liquid separation to obtain a fiber suspension.

[0042] S111. Add 0.55wt.% of methacryloyloxypropyltriethoxysilane to the fiber suspension, stir at 400rpm for 13h, then wash with deionized water until neutral, and adjust the beating degree to 45°SR to obtain modified cellulose short fiber.

[0043] S100. Polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles and silane coupling agent are added to water, mixed and dispersed to form a slurry, and the first slurry is obtained.

[0044] S201. The first pulp is formed by a double-wire forming method with a surface wire of 200 mesh and a core wire of 60 mesh to obtain the first wet paper blank.

[0045] S202. The first wet paper blank is impregnated in 8 wt.% polyamide polyamine epichlorohydrin resin, dehydrated, and then impregnated again in 18 wt.% melamine formaldehyde resin solution for directional impregnation to obtain the second wet paper blank.

[0046] S203. The second wet paper blank is stretched by 16% in the longitudinal direction at a speed of 3m / min to obtain the wet paper blank.

[0047] S301. The wet paper blank is impregnated with glutaraldehyde solution to carry out a chemical cross-linking reaction, and cross-linked wet paper blank is obtained;

[0048] S302. Place the cross-linked wet paper blank in a vacuum dehydration device and treat it under a vacuum pressure of 70 kPa for 1.5 min to obtain the paper blank.

[0049] S303. Dry the paper blank at 100℃ for 3 hours to obtain electrolytic capacitor paper.

[0050] Example 2

[0051] This embodiment provides a high-compression-strength, low-explosion-rate electrolytic capacitor paper, which comprises the following components by weight percentage:

[0052] The composition consists of: polyethylene terephthalate microfibers (5 μm in diameter, 1 mm in length) 30%, modified cellulose short fibers (0.8 mm in length) 40%, aluminum silicate nanoparticles 15%, silane coupling agent 1.5%, and wet-strength resin 13.5%.

[0053] Its production process includes the following steps:

[0054] S110. Add a 10 wt.% sodium hydroxide solution to the cellulose short fiber slurry, react at 50°C for 60 min, wash with deionized water until neutral, and perform solid-liquid separation to obtain a fiber suspension.

[0055] S111. Add 0.5 wt.% of methacryloyloxypropyltriethoxysilane to the fiber suspension, stir at 200 rpm for 15 h, then wash with deionized water until neutral, adjust the beating degree to 40°SR, and obtain modified cellulose short fiber.

[0056] S100. Polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles and silane coupling agent are added to water, mixed and dispersed to form a slurry, and the first slurry is obtained.

[0057] S201. The first pulp is formed by a double-mesh forming method with a surface mesh of 180 mesh and a core mesh of 40 mesh to obtain the first wet paper blank.

[0058] S202. The first wet paper blank is immersed in a 5 wt.% melamine-formaldehyde resin solution, dehydrated, and then immersed again in a 15 wt.% melamine-formaldehyde resin solution for directional impregnation to obtain the second wet paper blank.

[0059] S203. The second wet paper blank is stretched by 12% in the longitudinal direction at a speed of 5m / min to obtain the wet paper blank.

[0060] S301. The wet paper blank is impregnated with glutaraldehyde solution to carry out a chemical cross-linking reaction, and cross-linked wet paper blank is obtained;

[0061] S302. Place the cross-linked wet paper blank in a vacuum dehydration device and treat it under a vacuum pressure of 50 kPa for 2 minutes to obtain the paper blank.

[0062] S303. Dry the paper blank at 80℃ for 4 hours to obtain electrolytic capacitor paper.

[0063] Example 3

[0064] This embodiment provides a high-compression-strength, low-explosion-rate electrolytic capacitor paper, which comprises the following components by weight percentage:

[0065] The composition consists of: polyethylene terephthalate microfibers (10 μm in diameter, 2 mm in length): 50%; modified cellulose short fibers (1.2 mm in length): 20%; aluminum silicate nanoparticles: 5%; silane coupling agent: 0.5%; and wet-strength resin: 24.5%.

[0066] Its production process includes the following steps:

[0067] S110. Add a 20 wt.% sodium hydroxide solution to the cellulose short fiber slurry, react at 80°C for 30 min, wash with deionized water until neutral, and perform solid-liquid separation to obtain a fiber suspension.

[0068] S111. Add 0.6 wt.% of methacryloyloxypropyltriethoxysilane to the fiber suspension, stir at 500 rpm for 10 h, then wash with deionized water until neutral, and adjust the beating degree to 30°SR to obtain modified cellulose short fiber.

[0069] S100. Polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles and silane coupling agent are added to water, mixed and dispersed to form a slurry, and the first slurry is obtained.

[0070] S201. The first pulp is formed by a double-mesh forming method with a surface mesh of 220 mesh and a core mesh of 80 mesh to obtain the first wet paper blank.

[0071] S202. The first wet paper blank is impregnated in 10 wt.% polyamide polyamine epichlorohydrin resin, dehydrated, and then impregnated again in 20 wt.% melamine formaldehyde resin solution for directional impregnation to obtain the second wet paper blank.

[0072] S203. Stretch the second wet paper blank by 18% in the longitudinal direction at a speed of 1 m / min to obtain the wet paper blank.

[0073] S301. The wet paper blank is impregnated with glutaraldehyde solution to carry out a chemical cross-linking reaction, and cross-linked wet paper blank is obtained;

[0074] S302. Place the cross-linked wet paper blank in a vacuum dehydration device and treat it under a vacuum pressure of 80 kPa for 1 min to obtain the paper blank.

[0075] S303. Dry the paper blank at 120℃ for 2 hours to obtain electrolytic capacitor paper.

[0076] Comparative Example 1

[0077] This comparative example provides an electrolytic capacitor paper with high compressive strength and low explosion rate, which is purchased externally.

[0078] Test data

[0079] The compressive strength, breakdown voltage, explosion rate, and electrolyte penetration time of Examples 1-3 and Comparative Example 1 were measured. The test methods are shown below, and the results are shown in Table 1. The results of the test of Example 1 and the reverse mercury intrusion porosimetry are shown in Table 2.

[0080] (1) Compressive strength: According to GB / T228.1-2021 "Metallic materials, tensile testing - Part 1: Test at room temperature", the test was performed using a universal testing machine. 10×10mm samples from Examples 1-3 and Comparative Example 1 were cut. 2 Electrolytic paper, stacked to a thickness of 1 mm, pre-compressed to eliminate gaps, and vertically compressed at a rate of 1 mm / min. The maximum load (N) at the moment of crushing is recorded: Compressive strength (MPa) = Maximum load (N) / Specimen cross-sectional area (mm²) 2 ).

[0081] (2) Breakdown voltage: According to the standard method (GB 12656-1990), the paper samples of Examples 1-3 and Comparative Example 1 were dried at 105±5℃ for 1 hour to avoid the influence of moisture absorption. The double-layer paper samples were placed between the electrodes and the voltage was increased uniformly at a rate of 10-20s until breakdown. One point was measured at a spacing of 50-60mm, for a total of 20 valid points. Outliers were removed. The result was calculated as follows: the average breakdown voltage (V / layer) = the arithmetic mean of 20 points / 2. The coefficient of variation needs to be reported.

[0082] (3) Explosion rate: The capacitor was injected with electrolyte, sealed and placed in a constant temperature chamber (85℃); 1.5 times the rated voltage was applied and the number of failures was recorded within 3000 hours; Explosion rate (%) = (number of failure samples / total number of samples) × 100%.

[0083] (4) Electrolyte permeation time: Immerse the electrolytic paper vertically into the electrolyte and measure the change in liquid level rise over time. Saturation time determination: The time it takes for the liquid level to stabilize is the permeation time.

[0084] (5) Mercury porosimetry: According to ASTM D4404-18 standard, cut 10×10mm... 2Paper samples were vacuum dried at 105℃ for 24 hours to remove adsorbed water. A Micromeritics AutoPore V-type mercury porosimeter was used with the following parameters: mercury contact angle 140°, surface tension 485 mN / m, and pressure range 0.1-400 MPa. The pore distribution was calculated using the relationship between pressure P and pore size r: P=-2γcosθ / r. Macropores (5-400 μm) were measured in the low-pressure range, and micropores (0.003-5 μm) were measured in the high-pressure range. The results are shown in Table 2.

[0085] Table 1

[0086]

[0087] As shown in Table 1, this invention, through triple innovation in materials, structure, and process, achieves improved compressive strength, increased breakdown voltage, and reduced 3000-hour explosion rate while maintaining rapid electrolyte penetration, far exceeding the performance limits of traditional products. The data from the embodiments fully cover the scope of the claims, and the testing methods comply with national / industry standards.

[0088] As shown in Table 2, the 5~15μm pore size range accounts for 54.4% of the total pore volume, which matches the 60-mesh forming process of the core layer mesh, ensuring rapid electrolyte conduction; the 0.5~2μm micropore region accounts for 21.2%, and combined with <0.5μm nano-filled pores, the total micropore volume reaches 26.8%, corresponding to the 200-mesh high-density design of the surface layer mesh, effectively suppressing electrolyte over-immersion; the core layer macropores dominate the pore volume to ensure permeation efficiency, and the surface micropores construct a barrier layer, together realizing the design of "dense barrier on the surface layer + permeable conduction in the core layer", providing a structural basis for uniform electrolyte impregnation and explosion-proof performance.

[0089] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A high-compression-strength, low-explosion-rate electrolytic capacitor paper, characterized in that, The electrolytic capacitor paper comprises the following components by weight percentage and totaling 100%: polyethylene terephthalate microfibers: 30-50%, modified cellulose short fibers: 20-40%, aluminum silicate nanoparticles: 5-15%, silane coupling agent: 0.5-1.5%, and wet-strength resin: 10-25%. The electrolytic capacitor paper has a layered gradient pore structure, and the electrolytic capacitor paper includes a surface region and a core region. The surface layer has a pore size of 0.5~2μm, and the core layer has a pore size of 5~10μm.

2. The electrolytic capacitor paper according to claim 1, characterized in that, The polyethylene terephthalate microfibers have a diameter of 5~10μm and a length of 1~2mm.

3. The electrolytic capacitor paper according to claim 1, characterized in that, The modified cellulose short fibers are pretreated softwood pulp with a freeness of 40-50°SR and a length of 0.8-1.2 mm.

4. A production process for high-compression-strength, low-explosion-rate electrolytic capacitor paper, characterized in that, The manufacturing process is used to produce the electrolytic capacitor paper as described in any one of claims 1-3, and includes the following steps: S100. The polyethylene terephthalate microfibers, modified cellulose short fibers, aluminum silicate nanoparticles and silane coupling agent are added to water, mixed and dispersed to form a slurry, and the first slurry is obtained. S200: The first pulp is sequentially subjected to double-wire forming, directional impregnation, and wet stretching to obtain a wet paper blank; S300. The wet paper blank is impregnated with glutaraldehyde for chemical cross-linking to obtain the electrolytic capacitor paper.

5. The production process according to claim 4, characterized in that, The method for preparing the modified cellulose short fibers in step S100 is as follows: S110. Add sodium hydroxide solution to cellulose short fiber slurry. After the reaction is complete, wash with deionized water until neutral and perform solid-liquid separation to obtain fiber suspension. S111. Methacryloxypropyltriethoxysilane is added to the fiber suspension, stirred, and then washed with deionized water until neutral to obtain the modified cellulose short fiber.

6. The production process according to claim 5, characterized in that, In step S110, the concentration of the sodium hydroxide solution is 10~20 wt.%, the reaction temperature is 50~80℃, and the reaction time is 30~60 min; In step S111, the amount of methacryloyloxypropyltriethoxysilane used is 0.5~0.6 wt.%, the stirring time is 10~15 h, and the stirring speed is 200~500 rpm.

7. The production process according to claim 4, characterized in that, Step S200 specifically includes: S201. The first pulp is formed by a double-mesh forming method with a surface mesh of 180-220 mesh and a core mesh of 40-80 mesh to obtain the first wet paper blank. S202. The first wet paper blank is immersed in 5~10wt.% of a first wet strength resin solution, dehydrated, and then immersed again in 15~20wt.% of a second wet strength resin solution to carry out the directional impregnation to obtain a second wet paper blank. S203. The second wet paper blank is stretched in the longitudinal direction by 12-18% at a speed of 1-5 m / min to obtain the wet paper blank.

8. The production process according to claim 7, characterized in that, In step S202, The first wet-strength resin solution includes a polyamide-polyamine-epoxychlorohydrin resin solution or a melamine-formaldehyde resin solution; The second wet-strength resin solution includes a polyamide-polyamine-epoxychlorohydrin resin solution or a melamine-formaldehyde resin solution.

9. The production process according to claim 4, characterized in that, Step S300 specifically includes: S301. The wet paper blank is impregnated with glutaraldehyde solution to carry out a chemical cross-linking reaction to obtain a cross-linked wet paper blank; S302. The cross-linked wet paper blank is placed in a vacuum dehydration device and treated under a vacuum pressure of 50~80kPa for 1~2 minutes to obtain the paper blank; S303. The paper blank is dried at 80~120℃ for 2~4h to obtain the electrolytic capacitor paper.

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