Production method of capacitor aluminum plastic film and aluminum electrolytic capacitor formed foil

Abstract

The invention provides a production method of a capacitor aluminum plastic film and an aluminum electrolytic capacitor formed foil, relates to the field of formed foil production, and aims at providing a high-performance aluminum plastic film structure and a preparation process of the formed foil. The aluminum plastic film sequentially comprises an aluminum electrolytic capacitor formed foil, a bonding layer and a heat sealing layer from inside to outside. The bonding layer is composed of maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin, and the heat sealing layer is formed by compounding polypropylene and polyphenylene sulfide. According to the production of the formed foil, the thickness and the compactness of an oxidation film are gradually improved through multi-section electrolytic oxidation and optimized combination of multiple additives, the pressure resistance, the specific volume and the mechanical strength of the formed foil are remarkably improved, and meanwhile the leakage current is reduced.

Description

Technical Field

[0001] The invention belongs to the field of chemically formed foil production, in particular to a method for producing capacitor aluminum-plastic film and aluminum electrolytic capacitor chemically formed foil. Background Art

[0002] Aluminum electrolytic capacitors have been widely used in power electronics, communication equipment, household appliances and other fields due to their high capacity and high withstand voltage characteristics. As the core component of aluminum electrolytic capacitors, the quality of formed foil directly affects the performance and life of the capacitor. The traditional production method of formed foil usually adopts a single electrolytic oxidation process. Although it can form a certain oxide film, it has deficiencies in film thickness, density and uniformity, resulting in limited withstand voltage and capacitance performance of the capacitor. In addition, the traditional method has high requirements for environmental control during the production process and low production efficiency, which makes it difficult to meet the needs of modern industry for high-performance capacitors.

[0003] In recent years, with the rapid development of electronic technology, the performance requirements for aluminum electrolytic capacitors have become increasingly higher, especially under harsh conditions such as high frequency, high temperature and high humidity, the stability and reliability of capacitors face greater challenges. The existing chemical foil production technology still has a lot of room for improvement in terms of improving the dielectric strength of the oxide film, reducing leakage current and improving mechanical strength. For example, although the performance of the oxide film can be improved by adding some additives, the type and amount of these additives have a great influence on the final performance of the film and need to be further optimized. In addition, energy consumption and environmental pollution in the production process are also receiving increasing attention. How to reduce production costs and environmental impact while ensuring product quality is an important issue facing the current chemical foil production technology. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil.

[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil, comprising the following steps:

[0006] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment, use ultrapure water at 95±2℃, treat for 10-12 minutes, and form a pre-oxidation layer;

[0007] The first stage of electrolytic oxidation: the corroded aluminum foil after hydration treatment is placed in a 4.0wt% boric acid, 3.0wt% phosphoric acid, 0.5wt% ammonium adipate solution, 0.01wt% to 0.03wt% nano titanium dioxide, 0.05wt% to 0.1wt% nano aluminum oxide, 0.1wt% polyethylene glycol are added, and the pH is adjusted to 5.5 to 6.0 with ammonia water. The voltage is 200 to 300V, the pulse mode, the duty cycle is 30%, the temperature is 45±2℃, and the electrolysis is carried out for 15 to 20min.

[0008] The second stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation is placed in a solution of 6.0wt% boric acid, 5.0wt% phosphoric acid, and 0.3wt% ammonium adipate, and the pH is adjusted to 6.0-6.5 with aqueous ammonia. The voltage is 250-350V, the temperature is 50±2°C, and the electrolysis is performed for 15-20min.

[0009] Intermediate treatment I: The aluminum foil after the second stage of electrolytic oxidation is subjected to intermediate treatment, rinsed with deionized water, and then immersed in a 0.1wt% to 0.5wt% citric acid and 0.02wt% to 0.06wt% sodium gluconate solution, the temperature is controlled at 35°C to 40°C, and the time is 5 to 10 minutes;

[0010] The third stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation is placed in a solution of 8.0wt% boric acid, 7.0wt% phosphoric acid, and 0.2wt% ammonium adipate, 0.02wt% to 0.06wt% of nano zinc oxide particles are added, the pH is adjusted to 6.5 to 7.0 with ammonia water, the voltage is 300 to 400V, a DC superimposed high-frequency pulse is used, the temperature is 55±2°C, and the electrolysis is performed for 20 to 25min;

[0011] Feed slot treatment: the aluminum foil after electrolytic oxidation in the third stage is placed in the feed slot, 1.0wt% to 2.0wt% ammonium adipate, 0.02wt% to 0.05wt% polyvinyl pyrrolidone, 0.1wt% to 0.3wt% PEG-200 solution are added to the feed slot, the temperature is controlled at 40℃ to 45℃, and the treatment time is 10 to 17min;

[0012] Calcination I: The aluminum foil treated by the feed slot is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 200-250°C, and the calcination time is 25-30 minutes;

[0013] Medium treatment II: rinse with deionized water, then soak in an acetic acid solution containing 0.2wt% to 0.5wt%, with 0.01wt% to 0.03wt% chitosan added to the acetic acid solution, the temperature is controlled at 30℃ to 35℃, and the time is 5 to 9 minutes;

[0014] The fourth stage of electrolytic oxidation I: the aluminum foil after the treatment II is placed in a solution of 10.0wt% boric acid, 9.0wt% phosphoric acid, and 0.1wt% ammonium adipate, and the pH is adjusted to 6.5-7.0 with ammonia water. The voltage is 350-450V, the temperature is 60±2°C, and the electrolysis is performed for 25-30min.

[0015] The fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I, and perform electrolytic oxidation treatment again;

[0016] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent to the calcination furnace, protected by nitrogen, the temperature is controlled at 250℃~300℃, and the calcination time is 15~35min;

[0017] The fourth stage electrolytic oxidation III: repeat the process parameters and formula of the fourth stage electrolytic oxidation I, and perform electrolytic oxidation treatment again;

[0018] Fourth stage electrolytic oxidation IV: the aluminum foil of the fourth stage electrolytic oxidation III is placed in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution, and the pH is adjusted to 6.5-7.0 with ammonia water, the voltage is 400-500V, the pulse mode, the duty cycle is 50%, the temperature is 60±2°C, and the electrolysis is performed for 25-30min;

[0019] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent to the calcination furnace, the nitrogen protection temperature is controlled at 300°C to 350°C, and the calcination time is 20 to 40 minutes;

[0020] Post-treatment: immersing in 0.1wt% to 0.3wt% silane coupling agent solution, infrared radiation for 30 to 50 minutes, wavelength of 3 to 5μm, and vacuum drying to obtain the final formed aluminum electrolytic capacitor foil.

[0021] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melted and stirred at 80-120°C to form an adhesive layer slurry, which is evenly coated on the surface of aluminum electrolytic capacitor foil by a scraping process, with a thickness controlled at 20-30μm, and an adhesive layer is formed after curing; then polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 200-240°C through a twin-screw extruder, with a thickness controlled at 50-80μm; finally, a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process, with a hot pressing temperature of 160-180°C and a pressure of 8-12MPa, and the capacitor aluminum-plastic film is obtained after cooling and shaping.

[0022] Preferably, the conductivity of the ultrapure water is ≤0.1 μS / cm, the particle size of the nano-titanium dioxide is 10 to 50 nm, and the particle size of the nano-alumina in the nano-alumina dispersion is 20 to 80 nm.

[0023] Preferably, in all electrolytic oxidation steps, the electrolytic cell uses titanium-based coated electrodes with an electrode spacing of 10 to 30 mm; the electrolyte circulation flow rate is 0.5 to 2.0 m / s, and the liquid level height difference is controlled to be ±2 mm.

[0024] Preferably, the frequency of the pulse mode in the first stage of electrolytic oxidation and the fourth stage of electrolytic oxidation is 100-500 Hz, and the waveform is a square wave or a trapezoidal wave.

[0025] Preferably, the concentration of sodium gluconate used in the intermediate treatment I is 0.01-0.05wt%, the pH value of the solution is 3.5-4.5, and the immersion process in the intermediate treatment I is carried out under the protection of inert gas.

[0026] Preferably, the frequency of the high-frequency pulse in the third stage of electrolytic oxidation is 2 to 5 kHz, and the duty cycle is 20% to 40%.

[0027] Preferably, the particle size of the nano zinc oxide particles is 30 to 100 nm.

[0028] In the feed slot treatment: the molecular weight of the polyvinyl pyrrolidone is 10,000 to 50,000.

[0029] Preferably, the solution is kept uniform by magnetic stirring at a stirring rate of 100 to 300 rpm.

[0030] Preferably, the gas flow rate of nitrogen protection in the roasting I, roasting II and roasting III is 5-15 L / min; the heating rate is 5°C-10°C / min, and the cooling rate is 8-15°C / min.

[0031] Preferably, the chitosan has a deacetylation degree of ≥90% and a molecular weight of 50,000 to 200,000.

[0032] Preferably, the silane coupling agent is at least one of KH-550, KH-560 or KH-570.

[0033] The present invention provides a method for producing capacitor aluminum-plastic film and aluminum electrolytic capacitor formed foil. It has the following beneficial effects:

[0034] 1. Through multi-stage electrolytic oxidation treatment, the thickness and density of the oxide film are gradually increased, and the voltage resistance of the formed foil is significantly improved. The voltage resistance of Examples 1 to 5 is all above 530VF, and the highest can reach 551VF.

[0035] 2. The chemically formed foil produced by the method of the present invention has a relatively high specific volume. The specific volumes of Examples 1 to 5 are all above 0.95 μF / cm², and the highest can reach 0.986 μF / cm².

[0036] 3. The chemically formed foil produced by the method of the present invention has a lower leakage current. The leakage currents of Examples 1 to 5 are all below 56 μA / cm², and the lowest can reach 51 μA / cm². This is mainly due to the addition of nanomaterials such as nano-aluminum oxide and nano-zinc oxide during the electrolytic oxidation process. These materials can fill the micropores of the oxide film, improve the surface flatness of the oxide film, and increase the breakdown voltage, thereby reducing the leakage current. DETAILED DESCRIPTION

[0037] 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.

[0038] Embodiment 1:

[0039] A method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil comprises the following steps:

[0040] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment using ultrapure water at 95±2°C for 10 minutes.

[0041] The first stage of electrolytic oxidation: the hydrated corroded aluminum foil is placed in a 4.0wt% boric acid, 3.0wt% phosphoric acid, and 0.5wt% ammonium adipate solution, 0.01wt% nano titanium dioxide, 0.05wt% nano aluminum oxide, and 0.1wt% polyethylene glycol are added, and the pH is adjusted to 5.5-6.0 with ammonia water. The voltage is 200-300V, the pulse mode frequency is 100-500Hz, the waveform is square wave, the duty cycle is 30%, the temperature is 45±2°C, the electrolysis time is 15 minutes, and the electrolytic cell uses titanium-based coated electrodes with an electrode spacing of 10mm; the electrolyte circulation flow rate is 0.5m / s, and the liquid level height difference is controlled to be ±2mm.

[0042] Second stage electrolytic oxidation: The aluminum foil subjected to the first stage electrolytic oxidation was placed in a solution of 6.0wt% boric acid, 5.0wt% phosphoric acid, and 0.3wt% ammonium adipate. Ammonia water was used to adjust the pH to 6.0-6.5, the voltage was 250-350V, the temperature was 50±2°C, the DC mode was used, and the electrolysis time was 15 minutes.

[0043] Treatment I: The aluminum foil after the second electrolytic oxidation was rinsed with deionized water, and then immersed in a 0.1wt% citric acid and 0.01wt% sodium gluconate solution at a temperature of 35°C for 5 minutes.

[0044] The immersion process was carried out under the protection of inert gas.

[0045] The third stage of electrolytic oxidation: place the aluminum foil subjected to the first stage of electrolytic oxidation in a solution of 8.0wt% boric acid, 7.0wt% phosphoric acid, and 0.2wt% ammonium adipate, add 0.05wt% nano zinc oxide particles, adjust the pH to 6.5-7.0 with ammonia water, set the voltage to 300-400V, superimpose high-frequency pulses with direct current at a frequency of 2-5kHz, a duty cycle of 20%, a temperature of 55±2°C, and an electrolysis time of 20 minutes.

[0046] Feed tank treatment: The aluminum foil after the third electrolytic oxidation was placed in the feed tank, and 1.0wt% ammonium adipate, 0.02wt% polyvinyl pyrrolidone and 0.1wt% PEG-2000 were added to the feed tank. The solution temperature was controlled at 40°C and the treatment time was 10 minutes. The solution was kept uniform by magnetic stirring at a stirring rate of 100rpm.

[0047] Calcination I: The aluminum foil treated with the feed slot is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 200°C, the calcination time is 10 minutes, the nitrogen flow rate is 5L / min, the heating rate is 5°C / min, and the cooling rate is 8°C / min.

[0048] Medium treatment II: rinse with deionized water, then soak in a 0.2wt% acetic acid solution, add 0.01wt% chitosan to the acetic acid solution, control the temperature at 30°C, and soak for 5 minutes.

[0049] The fourth stage of electrolytic oxidation I: the aluminum foil after treatment II is placed in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution, and the pH is adjusted to 6.5-7.0 with ammonia water. The voltage is 350-450V, the temperature is 60±2°C, and the electrolysis time is 25 minutes.

[0050] Fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0051] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 250°C, the calcination time is 15 minutes, the nitrogen flow rate is 10L / min, the heating rate is 8°C / min, and the cooling rate is 12°C / min.

[0052] Fourth stage electrolytic oxidation III: Place the aluminum foil after the fourth stage electrolytic oxidation II in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution, use ammonia water to adjust the pH to 6.5-7.0, the voltage is 400-500V, the pulse mode, the duty cycle is 50%, the temperature is 60±2°C, and the electrolysis time is 25 minutes.

[0053] The fourth stage of electrolytic oxidation IV: repeat the process parameters and formula of the fourth stage of electrolytic oxidation III and perform electrolytic oxidation treatment again.

[0054] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 300-350°C, the calcination time is 20 minutes, the nitrogen flow rate is 15L / min, the heating rate is 10°C / min, and the cooling rate is 15°C / min.

[0055] Post-treatment: immersing in 0.1wt% silane coupling agent solution, infrared irradiation for 30 minutes, and vacuum drying to obtain the final aluminum electrolytic capacitor foil.

[0056] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melt-stirred at 115°C to form an adhesive layer slurry, and evenly coated on the surface of aluminum electrolytic capacitor foil by a doctor blade process, with a thickness of 30 μm, and an adhesive layer is formed after curing; then polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 200-240°C through a twin-screw extruder, with a thickness of 80 μm, and finally a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process, with a hot pressing temperature of 170°C and a pressure of 11 MPa, and the capacitor aluminum-plastic film is obtained after cooling and shaping.

[0057] Embodiment 2:

[0058] A method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil comprises the following steps:

[0059] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment using ultrapure water at 95±2°C for 12 minutes.

[0060] The first stage of electrolytic oxidation: the corroded aluminum foil after hydration treatment is placed in a 4.5wt% boric acid, 3.5wt% phosphoric acid, 0.6wt% ammonium adipate solution, and 0.02wt% nano titanium dioxide, 0.07wt% nano aluminum oxide and 0.15wt% polyethylene glycol are added. Ammonia water is used to adjust the pH to 5.8-6.2, the voltage is 220-320V, the pulse mode, the frequency is 200-500Hz, the waveform is a square wave, the duty cycle is 35%, the temperature is 47±2℃, the electrolysis time is 18 minutes, the electrolytic cell uses titanium-based coated electrodes, and the electrode spacing is 12mm; the electrolyte circulation flow rate is 1.0m / s, and the liquid level height difference is controlled to be ±2mm.

[0061] The second stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 6.5wt% boric acid, 5.5wt% phosphoric acid, and 0.4wt% ammonium adipate, and the pH was adjusted to 6.2-6.8 with aqueous ammonia. The voltage was 280-380V, the temperature was 52±2°C, and the DC mode was used. The electrolysis time was 18 minutes.

[0062] Treatment I: The aluminum foil after the second stage of electrolytic oxidation was rinsed with deionized water, and then immersed in a 0.15wt% citric acid and 0.02wt% sodium gluconate solution at a temperature of 38°C for 6 minutes. The immersion process was carried out under inert gas protection.

[0063] The third stage of electrolytic oxidation: place the aluminum foil subjected to the first stage of electrolytic oxidation in a solution of 8.5wt% boric acid, 7.5wt% phosphoric acid, and 0.3wt% ammonium adipate, add 0.1wt% nano zinc oxide particles, adjust the pH to 6.8-7.2 with ammonia water, set the voltage to 350-450V, superimpose high-frequency pulses with direct current, set the temperature to 58±2°C, and electrolyze for 25 minutes.

[0064] Feed trough treatment: The aluminum foil after the third electrolytic oxidation was placed in the feed trough, and 1.2wt% ammonium adipate, 0.03wt% polyvinyl pyrrolidone and 0.15wt% PEG-2000 solution were added to the feed trough. The temperature was controlled at 42°C, the treatment time was 12 minutes, and the solution was kept uniform by magnetic stirring at a stirring rate of 150rpm.

[0065] Calcination I: The aluminum foil treated with the feed slot is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 220°C, the calcination time is 12 minutes, the nitrogen flow rate is 8L / min, the heating rate is 6°C / min, and the cooling rate is 10°C / min.

[0066] Medium treatment II: rinse with deionized water, then soak in a 0.3wt% acetic acid solution, add 0.02wt% chitosan to the acetic acid solution, control the temperature at 32°C, and soak for 6 minutes.

[0067] The fourth stage of electrolytic oxidation I: the aluminum foil after treatment II is placed in a solution of 11.0wt% boric acid, 9.5wt% phosphoric acid, and 0.2wt% ammonium adipate, and the pH is adjusted to 6.8-7.2 with aqueous ammonia. The voltage is 400-500V, the temperature is 62±2°C, and the electrolysis time is 30 minutes.

[0068] Fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0069] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 280°C, the calcination time is 20 minutes, the nitrogen flow rate is 12L / min, the heating rate is 9°C / min, and the cooling rate is 14°C / min.

[0070] The fourth stage electrolytic oxidation III; the aluminum foil after the fourth stage electrolytic oxidation II is placed in a 11.5wt% boric acid, 10.0wt% phosphoric acid, 0.25wt% ammonium adipate solution, and the pH is adjusted to 7.0-7.4 with ammonia water, the voltage is 450-550V, the pulse mode, the frequency is 200-500Hz, the waveform is a trapezoidal wave, the duty cycle is 60%, the temperature is 64±2°C, and the electrolysis time is 32 minutes.

[0071] The fourth stage of electrolytic oxidation IV: repeat the process parameters and formula of the fourth stage of electrolytic oxidation III and perform electrolytic oxidation treatment again.

[0072] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 320-360°C, the calcination time is 25 minutes, the nitrogen flow rate is 18L / min, the heating rate is 12°C / min, and the cooling rate is 18°C / min.

[0073] Post-treatment: immersing in 0.2wt% silane coupling agent solution, infrared radiation for 45 minutes, and vacuum drying to obtain the final aluminum electrolytic capacitor foil.

[0074] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melt-stirred at 100°C to form an adhesive layer slurry, and evenly coated on the surface of aluminum electrolytic capacitor foil by a doctor blade process, with a thickness controlled at 20-30 μm, and an adhesive layer is formed after curing; then polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 200°C through a twin-screw extruder, with a thickness controlled at 75 μm; finally, a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process, with a hot pressing temperature of 165°C and a pressure of 8 MPa, and the capacitor aluminum-plastic film is obtained after cooling and shaping.

[0075] Embodiment 3:

[0076] A method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil comprises the following steps:

[0077] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment using ultrapure water at 95±2°C for 11 minutes.

[0078] The first stage of electrolytic oxidation: the hydrated corroded aluminum foil is placed in a 4.2wt% boric acid, 3.2wt% phosphoric acid, and 0.55wt% ammonium adipate solution, 0.015wt% nano titanium dioxide, 0.06wt% nano aluminum oxide, and 0.12wt% polyethylene glycol are added, and the pH is adjusted to 5.6-6.1 with ammonia water. The voltage is 210-310V, the pulse mode frequency is 150-450Hz, the waveform is square wave, the duty cycle is 32%, the temperature is 46±2℃, and the electrolysis time is 16 minutes.

[0079] The electrolytic cell uses titanium-based coated electrodes with an electrode spacing of 11 mm; the electrolyte circulation flow rate is 1.2 m / s, and the liquid level height difference is controlled to be ±2 mm.

[0080] The second stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 6.2wt% boric acid, 5.2wt% phosphoric acid, and 0.35wt% ammonium adipate, and the pH was adjusted to 6.1-6.6 with aqueous ammonia. The voltage was 260-360V, the temperature was 51±2°C, and the DC mode was used. The electrolysis time was 17 minutes.

[0081] Treatment I: The aluminum foil after the second stage of electrolytic oxidation was rinsed with deionized water, and then immersed in a 0.12wt% citric acid and 0.03wt% sodium gluconate solution at a temperature of 37°C for 7 minutes. The immersion process was carried out under the protection of inert gas.

[0082] The third stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 8.2wt% boric acid, 7.2wt% phosphoric acid, and 0.22wt% ammonium adipate, 0.04wt% nano zinc oxide particles were added, the pH was adjusted to 6.7-7.1 with ammonia water, the voltage was 330-430V, direct current was superimposed with high-frequency pulses, the frequency was 4-8kHz, the duty cycle was 25%, the temperature was 56±2°C, and the electrolysis time was 22 minutes.

[0083] Feed trough treatment: The aluminum foil after electrolytic oxidation in the third stage is placed in the feed trough, and 1.1wt% ammonium adipate, 0.04wt% polyvinyl pyrrolidone with a molecular weight of 30,000-70,000 and 0.2wt% PEG-200 solution are added to the feed trough. The temperature is controlled at 41°C, the treatment time is 11 minutes, and the solution is kept uniform by magnetic stirring at a stirring rate of 180rpm.

[0084] Calcination I: The aluminum foil treated with the feed slot was sent into the calcination furnace, protected by nitrogen, the temperature was controlled at 215°C, the calcination time was 11 minutes, the nitrogen flow rate was 7L / min, the heating rate was 7°C / min, and the cooling rate was 9°C / min.

[0085] Treatment II: rinse with deionized water, then soak in a solution containing 0.25wt% acetic acid, to which 0.03wt% chitosan is added, the temperature is controlled at 31°C, and the time is 7 minutes.

[0086] The fourth stage of electrolytic oxidation I: the aluminum foil after treatment II is placed in a solution of 10.5wt% boric acid, 9.8wt% phosphoric acid, and 0.15wt% ammonium adipate, and the pH is adjusted to 6.9-7.3 with aqueous ammonia. The voltage is 380-480V, the temperature is 61±2°C, and the electrolysis time is 28 minutes.

[0087] Fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0088] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 265°C, the calcination time is 18 minutes, the nitrogen flow rate is 9L / min, the heating rate is 8°C / min, and the cooling rate is 11°C / min.

[0089] The fourth stage of electrolytic oxidation III: the aluminum foil after the fourth stage of electrolytic oxidation II is placed in a 10.8wt% boric acid, 10.3wt% phosphoric acid, and 0.18wt% ammonium adipate solution, and the pH is adjusted to 7.1-7.5 with aqueous ammonia. The voltage is 430-530V, the pulse mode, the frequency is 250-550Hz, the waveform is a trapezoidal wave, the duty cycle is 65%, the temperature is 63±2°C, and the electrolysis time is 34 minutes.

[0090] The fourth stage of electrolytic oxidation IV: repeat the process parameters and formula of the fourth stage of electrolytic oxidation III and perform electrolytic oxidation treatment again.

[0091] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 315-355°C, the calcination time is 28 minutes, the nitrogen flow rate is 20L / min, the heating rate is 13°C / min, and the cooling rate is 20°C / min.

[0092] Post-treatment: immersing in 0.3wt% silane coupling agent solution, infrared irradiation for 40 minutes, and vacuum drying to obtain the final aluminum electrolytic capacitor foil.

[0093] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melt-stirred at 120°C to form an adhesive layer slurry, which is evenly coated on the surface of the aluminum electrolytic capacitor foil by a doctor blade process with a thickness of 30 μm. After curing, an adhesive layer is formed. Then, polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 240°C through a twin-screw extruder with a thickness of μm. Finally, a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process with a hot pressing temperature of 180°C and a pressure of 9 MPa. After cooling and shaping, the capacitor aluminum-plastic film is obtained.

[0094] Embodiment 4:

[0095] A method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil comprises the following steps:

[0096] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment using ultrapure water at 95±2°C for 10.5 minutes.

[0097] The first stage of electrolytic oxidation: the hydrated corroded aluminum foil is placed in a 4.1wt% boric acid, 3.1wt% phosphoric acid, and 0.52wt% ammonium adipate solution, 0.012wt% nano titanium dioxide, 0.06wt% nano aluminum oxide, and 0.11wt% polyethylene glycol are added, and the pH is adjusted to 5.7-6.1 with ammonia water. The voltage is 205-305V, the pulse mode frequency is 120-500Hz, the waveform is square wave, the duty cycle is 31%, the temperature is 45.5±2℃, the electrolysis time is 17 minutes, and the electrolytic cell uses titanium-based coated electrodes with an electrode spacing of 10.5mm; the electrolyte circulation flow rate is 1.1m / s, and the liquid level height difference is controlled to be ±2mm.

[0098] The second stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 6.1wt% boric acid, 5.1wt% phosphoric acid, and 0.32wt% ammonium adipate, and the pH was adjusted to 6.1-6.6 with aqueous ammonia. The voltage was 255-355V, the temperature was 50.5±2°C, and the DC mode was used. The electrolysis time was 17 minutes.

[0099] Treatment I: The aluminum foil after the second stage of electrolytic oxidation was rinsed with deionized water, and then immersed in a 0.11wt% citric acid and 0.025wt% sodium gluconate solution at a temperature of 36°C for 5.5 minutes. The immersion process was carried out under the protection of inert gas.

[0100] The third stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 8.1wt% boric acid, 7.1wt% phosphoric acid, and 0.21wt% ammonium adipate, 0.055wt% nano zinc oxide particles was added, the pH was adjusted to 6.6-7.1 with ammonia water, the voltage was 305-405V, direct current was superimposed with high-frequency pulses, the frequency was 3-6kHz, the duty cycle was 22%, the temperature was 55.5±2°C, and the electrolysis time was 21 minutes.

[0101] Feed trough treatment: The aluminum foil after the third electrolytic oxidation was placed in the feed trough, and 1.15wt% ammonium adipate, 0.035wt% polyvinyl pyrrolidone and 0.13wt% PEG-2000 solution were added to the feed trough. The temperature was controlled at 40.5°C, the treatment time was 11.5 minutes, and the solution was kept uniform by magnetic stirring at a stirring rate of 120rpm.

[0102] Calcination I: The aluminum foil treated with the feed slot was sent into the calcination furnace, protected by nitrogen, the temperature was controlled at 205°C, the calcination time was 11 minutes, the nitrogen flow rate was 6L / min, the heating rate was 5.5°C / min, and the cooling rate was 8°C / min.

[0103] Medium treatment II: rinse with deionized water, then soak in a solution containing 0.22wt% acetic acid, with 0.02wt% chitosan added to the acetic acid solution, the temperature was controlled at 30.5℃, and the time was 5.5 minutes.

[0104] The fourth stage of electrolytic oxidation I: the aluminum foil after treatment II is placed in a solution of 10.2wt% boric acid, 9.2wt% phosphoric acid, and 0.11wt% ammonium adipate, and the pH is adjusted to 6.6-7.1 with aqueous ammonia. The voltage is 355-455V, the temperature is 60.5±2°C, and the electrolysis time is 27 minutes.

[0105] Fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0106] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 252°C, the calcination time is 16 minutes, the nitrogen flow rate is 11L / min, the heating rate is 8°C / min, and the cooling rate is 13°C / min.

[0107] Fourth stage electrolytic oxidation III: Place the aluminum foil after the fourth stage electrolytic oxidation II in a 10.3wt% boric acid, 9.3wt% phosphoric acid, 0.12wt% ammonium adipate solution, use ammonia water to adjust the pH to 6.7-7.2, the voltage is 410-510V, the pulse mode, the duty cycle is 52%, the temperature is 61±2°C, and the electrolysis time is 28 minutes.

[0108] The fourth stage of electrolytic oxidation IV: repeat the process parameters and formula of the fourth stage of electrolytic oxidation III and perform electrolytic oxidation treatment again.

[0109] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 302-352°C, the calcination time is 21 minutes, the nitrogen flow rate is 16L / min, the heating rate is 11°C / min, and the cooling rate is 17°C / min.

[0110] Post-treatment: immersing in 0.15wt% silane coupling agent solution, infrared radiation for 42 minutes, and vacuum drying to obtain the final aluminum electrolytic capacitor foil.

[0111] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melt-stirred at 100°C to form an adhesive layer slurry, and evenly coated on the surface of the aluminum electrolytic capacitor foil by a doctor blade process, with a thickness controlled at 20 μm, and an adhesive layer is formed after curing; then polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 230°C through a twin-screw extruder, with a thickness controlled at 60 μm, and finally a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process, with a hot pressing temperature of 175°C and a pressure of 11 Pa, and the capacitor aluminum-plastic film is obtained after cooling and shaping.

[0112] Embodiment 5:

[0113] A method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil comprises the following steps:

[0114] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment using ultrapure water at 95±2°C for 13 minutes.

[0115] The first stage of electrolytic oxidation: the hydrated corroded aluminum foil is placed in a 4.3wt% boric acid, 3.3wt% phosphoric acid, and 0.58wt% ammonium adipate solution, 0.018wt% nano titanium dioxide, 0.08wt% nano aluminum oxide, and 0.14wt% polyethylene glycol are added, and the pH is adjusted to 5.8-6.3 with ammonia water. The voltage is 215-315V, the pulse mode frequency is 180-500Hz, the waveform is square wave, the duty cycle is 33%, the temperature is 47±2℃, the electrolysis time is 19 minutes, the electrolytic cell uses titanium-based coated electrodes, and the electrode spacing is 13mm; the electrolyte circulation flow rate is 1.3m / s, and the liquid level height difference is controlled to be ±2mm.

[0116] The second stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 6.3wt% boric acid, 5.3wt% phosphoric acid, and 0.38wt% ammonium adipate, and the pH was adjusted to 6.3-6.8 with aqueous ammonia. The voltage was 265-365V, the temperature was 53±2°C, and the DC mode was used. The electrolysis time was 19 minutes.

[0117] Treatment I: The aluminum foil after the second stage of electrolytic oxidation was rinsed with deionized water, and then immersed in a 0.13wt% citric acid and 0.04wt% sodium gluconate solution at a temperature of 39°C for 6.5 minutes. The immersion process was carried out under inert gas protection.

[0118] The third stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 8.3wt% boric acid, 7.3wt% phosphoric acid, and 0.23wt% ammonium adipate, 0.065wt% nano zinc oxide particles was added, the pH was adjusted to 6.9-7.3 with ammonia water, the voltage was 310-410V, direct current was superimposed with high-frequency pulses, the frequency was 4-7kHz, the duty cycle was 27%, the temperature was 57±2°C, and the electrolysis time was 23 minutes.

[0119] Feed trough treatment: The aluminum foil after the third electrolytic oxidation was placed in the feed trough, and 1.25wt% ammonium adipate, 0.05wt% polyvinyl pyrrolidone and 0.16wt% PEG-2000 solution were added to the feed trough. The temperature was controlled at 43°C, the treatment time was 13 minutes, and the solution was kept uniform by magnetic stirring at a stirring rate of 130rpm.

[0120] Calcination I: The aluminum foil treated with the feed slot was sent into the calcination furnace, protected by nitrogen, the temperature was controlled at 225°C, the calcination time was 13 minutes, the nitrogen flow rate was 9L / min, the heating rate was 6.5°C / min, and the cooling rate was 10°C / min.

[0121] Medium treatment II: rinse with deionized water, then soak in a solution containing 0.28wt% acetic acid, to which 0.035wt% chitosan was added, the temperature was controlled at 33°C, and the time was 8 minutes.

[0122] The fourth stage of electrolytic oxidation I: the aluminum foil after treatment II is placed in a solution of 10.8wt% boric acid, 9.5wt% phosphoric acid, and 0.13wt% ammonium adipate, and the pH is adjusted to 6.9-7.4 with aqueous ammonia. The voltage is 365-465V, the temperature is 63±2°C, and the electrolysis time is 31 minutes.

[0123] Fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0124] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 275°C, the calcination time is 22 minutes, the nitrogen flow rate is 14L / min, the heating rate is 9°C / min, and the cooling rate is 16°C / min.

[0125] Fourth stage electrolytic oxidation III: Place the aluminum foil after the fourth stage electrolytic oxidation II in a solution of 11.2wt% boric acid, 10.2wt% phosphoric acid, and 0.15wt% ammonium adipate, adjust the pH to 7.2-7.6 with aqueous ammonia, and use a voltage of 420-520V, a pulse mode, a duty cycle of 55%, a temperature of 66±2°C, and an electrolysis time of 35 minutes.

[0126] The fourth stage of electrolytic oxidation IV: repeat the process parameters and formula of the fourth stage of electrolytic oxidation III and perform electrolytic oxidation treatment again.

[0127] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 310-360°C, the calcination time is 29 minutes, the nitrogen flow rate is 21L / min, the heating rate is 14°C / min, and the cooling rate is 22°C / min.

[0128] Post-treatment: immersing in 0.2wt% silane coupling agent solution, infrared radiation for 55 minutes, and vacuum drying to obtain the final aluminum electrolytic capacitor foil.

[0129] Post-treatment: immersion in 0.3% silane coupling agent solution, infrared radiation for 40 minutes, and vacuum drying to obtain the final aluminum electrolytic capacitor foil.

[0130] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melt-stirred at 95°C to form an adhesive layer slurry, which is evenly coated on the surface of the aluminum electrolytic capacitor foil by a doctor blade process with a thickness of 25 μm. After curing, an adhesive layer is formed; then polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 220°C through a twin-screw extruder with a thickness of 60 μm. Finally, a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process with a hot pressing temperature of 175°C and a pressure of 10 MPa. After cooling and shaping, the capacitor aluminum-plastic film is obtained.

[0131] It should be noted that boric acid, as a weak acid buffer, controls the pH stability of the electrolyte, participates in the lattice construction of the oxide film Al2O3, and improves the dielectric strength.

[0132] It should be noted that phosphoric acid can enhance the ionic conductivity of the electrolyte and promote the formation of a porous oxide film. H2PO4~ ions can be inserted into the oxide film structure to enhance corrosion resistance.

[0133] It should be noted that the concentration of boric acid increases from 4% to 10%, and the concentration of phosphoric acid increases from 3% to 9%, and the voltage is increased in stages to achieve gradient growth of the oxide film.

[0134] It should be noted that nano-TiO2 forms heterogeneous nucleation points in the oxide layer, reducing the crystallization barrier of the oxide film.

[0135] It should be noted that nano Al2O 3， Fill the micropores in the oxide film, improve surface flatness, and increase breakdown voltage.

[0136] It should be noted that nano ZnO introduces semiconductor properties in the third stage of oxidation to optimize dielectric loss.

[0137] It should be noted that polyethylene glycol (PEG) stabilizes the dispersion of nanoparticles through steric hindrance effect, reduces the surface tension of the electrolyte, prevents nanoparticle agglomeration, ensures the uniformity of the electrolyte, and thus improves the quality of the oxide film.

[0138] It should be noted that polyvinyl pyrrolidone (PVP) forms a molecular chain network in the feed slot and repairs microcracks in the oxide film.

[0139] It should be noted that chitosan constructs an organic-inorganic hybrid interface layer through the coordination of -NH2 and Al-OH.

[0140] It should be noted that ammonium adipate provides NH4 + Inhibit hydrogen evolution reaction, adipate chelates Al 3+ Controls the crystallization rate.

[0141] It should be noted that citric acid chelates metal impurity ions and modifies the surface of the oxide film through carboxylic acid groups.

[0142] Comparative Example 1:

[0143] A method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil comprises the following steps:

[0144] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment, use ultrapure water at 95±2°C, treat for 10 to 12 minutes, and form a pre-oxidation layer.

[0145] The first stage of electrolytic oxidation: the hydrated corroded aluminum foil is placed in a 4.0wt% boric acid, 3.0wt% phosphoric acid, and 0.5wt% ammonium adipate solution without adding nano-titanium dioxide, nano-aluminum oxide, and polyethylene glycol. Ammonia water is used to adjust the pH to 5.5-6.0. The voltage is 200-300V, the pulse mode is used, the duty cycle is 30%, the temperature is 45±2°C, and the electrolysis is performed for 15-20min.

[0146] The second stage of electrolytic oxidation: place the aluminum foil subjected to the first stage of electrolytic oxidation in a solution of 6.0wt% boric acid, 5.0wt% phosphoric acid, and 0.3wt% ammonium adipate, adjust the pH to 6.0-6.5 with aqueous ammonia, and perform electrolysis for 15-20 minutes at a voltage of 250-350V and a temperature of 50±2°C.

[0147] Intermediate treatment I: The aluminum foil after the second stage of electrolytic oxidation is subjected to intermediate treatment, rinsed with deionized water, and then immersed in 0.1wt%~0.5wt% citric acid, 0.02wt%~0.06wt% sodium gluconate solution, the temperature is controlled at 35℃~40℃, and the time is 5~10min.

[0148] The third stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation was placed in a solution of 8.0wt% boric acid, 7.0wt% phosphoric acid, and 0.2wt% ammonium adipate without adding nano zinc oxide particles. Ammonia water was used to adjust the pH to 6.5-7.0. The voltage was 300-400V, direct current was superimposed with high-frequency pulses, the temperature was 55±2°C, and the electrolysis was carried out for 20-25min.

[0149] Feed slot treatment: the aluminum foil after electrolytic oxidation in the third stage is placed in the feed slot, and 1.0wt% to 2.0wt% ammonium adipate, 0.02wt% to 0.05wt% polyvinyl pyrrolidone, and 0.1wt% to 0.3wt% PEG-200 solution are added to the feed slot. The temperature is controlled at 40°C to 45°C, and the treatment time is 10 to 17 minutes.

[0150] Calcination I: The aluminum foil treated by the feed slot is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 200-250°C, and the calcination time is 25-30 minutes.

[0151] Medium treatment II: Rinse with deionized water, then soak in an acetic acid solution containing 0.2wt% to 0.5wt% chitosan. The temperature is controlled at 30℃ to 35℃ for 5 to 9 minutes.

[0152] The fourth stage of electrolytic oxidation I: the aluminum foil after the treatment II is placed in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution, and the pH is adjusted to 6.5-7.0 with ammonia water. The voltage is 350-450V, the temperature is 60±2°C, and the electrolysis is carried out for 25-30min.

[0153] Fourth stage electrolytic oxidation II: Repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0154] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent into a calcination furnace, protected by nitrogen, with the temperature controlled at 250°C to 300°C, and the calcination time is 15 to 35 minutes.

[0155] Fourth stage electrolytic oxidation III: Repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0156] Fourth stage electrolytic oxidation IV: The aluminum foil of the fourth stage electrolytic oxidation III is placed in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution, and the pH is adjusted to 6.5-7.0 with ammonia water. The voltage is 400-500V, the pulse mode, the duty cycle is 50%, the temperature is 60±2°C, and the electrolysis is carried out for 25-30min.

[0157] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent to the calcination furnace, the nitrogen protection temperature is controlled at 300℃~350℃, and the calcination time is 20~40min.

[0158] Post-treatment: immersing in 0.1wt% to 0.3wt% silane coupling agent solution, infrared radiation for 30 to 50 minutes, wavelength of 3 to 5μm, and vacuum drying to obtain the final formed aluminum electrolytic capacitor foil.

[0159] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melt-stirred at 115°C to form an adhesive layer slurry, and evenly coated on the surface of aluminum electrolytic capacitor foil by a doctor blade process, with a thickness of 30 μm, and an adhesive layer is formed after curing; then polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 200-240°C through a twin-screw extruder, with a thickness of 80 μm, and finally a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process, with a hot pressing temperature of 170°C and a pressure of 11 MPa, and the capacitor aluminum-plastic film is obtained after cooling and shaping.

[0160] Comparative Example 2:

[0161] A method for producing a capacitor aluminum-plastic film and an aluminum electrolytic capacitor formed foil comprises the following steps:

[0162] Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment using ultrapure water at 95±2°C for 10 minutes.

[0163] The first stage of electrolytic oxidation: the hydrated corroded aluminum foil is placed in a 4.0wt% boric acid, 3.0wt% phosphoric acid, and 0.5wt% ammonium adipate solution, 0.01wt% nano titanium dioxide, 0.05wt% nano aluminum oxide, and 0.1wt% polyethylene glycol are added, and the pH is adjusted to 5.5-6.0 with ammonia water. The voltage is 200-300V, the pulse mode frequency is 100-500Hz, the waveform is square wave, the duty cycle is 30%, the temperature is 45±2°C, the electrolysis time is 15 minutes, and the electrolytic cell uses titanium-based coated electrodes with an electrode spacing of 10mm; the electrolyte circulation flow rate is 0.5m / s, and the liquid level height difference is controlled to be ±2mm.

[0164] Second stage electrolytic oxidation: The aluminum foil subjected to the first stage electrolytic oxidation was placed in a solution of 6.0wt% boric acid, 5.0wt% phosphoric acid, and 0.3wt% ammonium adipate. Ammonia water was used to adjust the pH to 6.0-6.5, the voltage was 250-350V, the temperature was 50±2°C, the DC mode was used, and the electrolysis time was 15 minutes.

[0165] Treatment I: The aluminum foil after the second electrolytic oxidation was rinsed with deionized water, and then immersed in a 0.1wt% citric acid and 0.01wt% sodium gluconate solution at a temperature of 35°C for 5 minutes.

[0166] The immersion process was carried out under the protection of inert gas.

[0167] The third stage of electrolytic oxidation: place the aluminum foil subjected to the first stage of electrolytic oxidation in a solution of 8.0wt% boric acid, 7.0wt% phosphoric acid, and 0.2wt% ammonium adipate, add 0.05wt% nano zinc oxide particles, adjust the pH to 6.5-7.0 with ammonia water, set the voltage to 300-400V, superimpose high-frequency pulses with direct current at a frequency of 2-5kHz, a duty cycle of 20%, a temperature of 55±2°C, and an electrolysis time of 20 minutes.

[0168] Calcination I: The aluminum foil treated with the feed slot is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 200°C, the calcination time is 10 minutes, the nitrogen flow rate is 5L / min, the heating rate is 5°C / min, and the cooling rate is 8°C / min.

[0169] Medium treatment II: rinse with deionized water, then soak in a 0.2wt% acetic acid solution, add 0.01wt% chitosan to the acetic acid solution, control the temperature at 30°C, and soak for 5 minutes.

[0170] The fourth stage of electrolytic oxidation I: the aluminum foil after treatment II is placed in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution, and the pH is adjusted to 6.5-7.0 with ammonia water. The voltage is 350-450V, the temperature is 60±2°C, and the electrolysis time is 25 minutes.

[0171] Fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I and perform electrolytic oxidation treatment again.

[0172] Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 250°C, the calcination time is 15 minutes, the nitrogen flow rate is 10L / min, the heating rate is 8°C / min, and the cooling rate is 12°C / min.

[0173] Fourth stage electrolytic oxidation III: Place the aluminum foil after the fourth stage electrolytic oxidation II in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution, use ammonia water to adjust the pH to 6.5-7.0, the voltage is 400-500V, the pulse mode, the duty cycle is 50%, the temperature is 60±2°C, and the electrolysis time is 25 minutes.

[0174] The fourth stage of electrolytic oxidation IV: repeat the process parameters and formula of the fourth stage of electrolytic oxidation III and perform electrolytic oxidation treatment again.

[0175] Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent into the calcination furnace, protected by nitrogen, the temperature is controlled at 300-350°C, the calcination time is 20 minutes, the nitrogen flow rate is 15L / min, the heating rate is 10°C / min, and the cooling rate is 15°C / min.

[0176] Post-treatment: immersing in 0.1wt% silane coupling agent solution, infrared irradiation for 30 minutes, and vacuum drying to obtain the final aluminum electrolytic capacitor foil.

[0177] Preparation of capacitor aluminum-plastic film: maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin are mixed in a mass ratio of 5:2:1, melt-stirred at 115°C to form an adhesive layer slurry, and evenly coated on the surface of aluminum electrolytic capacitor foil by a doctor blade process, with a thickness of 30 μm, and an adhesive layer is formed after curing; then polypropylene and polyphenylene sulfide are melt-blended in a mass ratio of 7:3, and a heat-sealing layer film is formed at 200-240°C through a twin-screw extruder, with a thickness of 80 μm, and finally a heat-sealing layer is compounded on the surface of the adhesive layer by a hot pressing lamination process, with a hot pressing temperature of 170°C and a pressure of 11 MPa, and the capacitor aluminum-plastic film is obtained after cooling and shaping.

[0178] The capacitor aluminum-plastic films obtained in Examples 1 to 5 and Comparative Examples 1 to 2 were tested for various parameters. The test method was based on EIAJRC-2364A, Tr'120 represents the withstand voltage rise time after boiling for 120 minutes, and the test parameters are listed in Table 1:

[0179] Table 1

[0180] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A capacitor aluminum-plastic film, characterized in that: From the inside to the outside, it includes aluminum electrolytic capacitor forming foil, bonding layer and heat sealing layer; The adhesive layer is an adhesive composed of maleic anhydride modified polyolefin, diisocyanate and glycidyl ether type epoxy resin; The heat sealing layer is composited from polypropylene and polyphenylene sulfide.

2. A method for producing aluminum electrolytic capacitor foil, characterized in that: The following steps are involved: Hydration treatment: After unwinding the corroded aluminum foil, perform boiling water hydration treatment; The first stage of electrolytic oxidation: the corroded aluminum foil after hydration treatment is placed in a 4.0wt% boric acid, 3.0wt% phosphoric acid, and 0.5wt% ammonium adipate solution for electrolysis for 15 to 20 minutes; The second electrolytic oxidation: the aluminum foil subjected to the first electrolytic oxidation is placed in a 6.0wt% boric acid, 5.0wt% phosphoric acid, and 0.3wt% ammonium adipate solution for electrolysis for 15 to 20 minutes; Intermediate treatment I: The aluminum foil after the second stage of electrolytic oxidation is subjected to intermediate treatment, the temperature is controlled at 35°C to 40°C, and the time is 5 to 10 minutes; The third stage of electrolytic oxidation: the aluminum foil subjected to the first stage of electrolytic oxidation is placed in a solution of 8.0wt% boric acid, 7.0wt% phosphoric acid, and 0.2wt% ammonium adipate for electrolysis for 20 to 25 minutes; Feeding slot treatment: the aluminum foil after electrolytic oxidation in the third stage is placed in the feeding slot, the temperature is controlled at 40℃~45℃, and the treatment time is 10~17min; Calcination I: Feed the aluminum foil treated by the feed slot into the calcination furnace, control the temperature at 200-250°C, and the calcination time is 25-30 minutes; Medium treatment II: soak the aluminum foil treated by calcination I in a solution containing 0.2wt% to 0.5wt% acetic acid, the temperature is controlled at 30℃ to 35℃, and the time is 5 to 9 minutes; The fourth stage of electrolytic oxidation I: the aluminum foil after the treatment II is placed in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution for electrolysis for 25 to 30 minutes; The fourth stage electrolytic oxidation II: repeat the process parameters and formula of the fourth stage electrolytic oxidation I, and perform electrolytic oxidation treatment again; Calcination II: The aluminum foil after the fourth stage of electrolytic oxidation II is sent to the calcination furnace, the temperature is controlled at 250℃~300℃, and the calcination time is 15~35min; The fourth stage electrolytic oxidation III: repeat the process parameters and formula of the fourth stage electrolytic oxidation I, and perform electrolytic oxidation treatment again; Fourth stage electrolytic oxidation IV: the aluminum foil of the fourth stage electrolytic oxidation III is placed in a 10.0wt% boric acid, 9.0wt% phosphoric acid, 0.1wt% ammonium adipate solution for electrolysis for 25 to 30 minutes; Calcination III: The aluminum foil after the fourth stage of electrolytic oxidation IV is sent to the calcination furnace, the temperature is controlled at 300°C to 350°C, and the calcination time is 20 to 40 minutes; Post-treatment: immersing in 0.1wt%-0.3wt% silane coupling agent solution, infrared radiation for 30-50min, wavelength 3-5μm, and vacuum drying to obtain the final formed aluminum electrolytic capacitor foil.

3. The method for producing aluminum electrolytic capacitor formed foil according to claim 2, characterized in that: The first stage of electrolytic oxidation adds 0.01wt% to 0.03wt% nano titanium dioxide, 0.05wt% to 0.1wt% nano aluminum oxide, 0.1wt% polyethylene glycol, and uses ammonia water to adjust the pH to 5.5 to 6.

0. The voltage is 200 to 300V, the pulse mode, the duty cycle is 30%, and the temperature is 45±2°C; In the second stage of electrolytic oxidation, ammonia water is used to adjust the pH to 6.0-6.5, the voltage is 250-350V, the temperature is 50±2℃, and the electrolysis is carried out for 15-20min; In the third stage, 0.02 wt% to 0.06 wt% of nano zinc oxide particles are added in electrolytic oxidation, and the pH is adjusted to 6.5 to 7.0 with ammonia water. The voltage is 300 to 400 V, and a high-frequency pulse is superimposed with direct current. The temperature is 55 ± 2 °C. The fourth stage of electrolytic oxidation I uses ammonia water to adjust the pH to 6.5-7.0, the voltage is 350-450V, and the temperature is 60±2℃; The fourth stage of electrolytic oxidation IV uses ammonia water to adjust the pH to 6.5-7.0, the voltage is 400-500V, the pulse mode, the duty cycle is 50%, and the temperature is 60±2°C.

4. The method for producing aluminum electrolytic capacitor foil according to claim 2, characterized in that: The intermediate treatment I is rinsed with deionized water, and then immersed in 0.1wt%~0.5wt% citric acid, 0.02wt%~0.06wt% sodium gluconate solution; 1.0wt%~2.0wt% ammonium adipate, 0.02wt%~0.05wt% polyvinyl pyrrolidone, 0.1wt%~0.3wt% PEG-200 solution are added in the feed slot treatment; 0.01wt%~0.03wt% chitosan is added in the intermediate treatment, and nitrogen protection is used in calcination I, calcination II and calcination III.

5. The method for producing aluminum electrolytic capacitor formed foil according to claim 2, characterized in that: In all electrolytic oxidation steps, the electrolytic cell uses titanium-based coated electrodes with an electrode spacing of 10 to 30 mm; the electrolyte circulation flow rate is 0.5 to 2.0 m / s, and the liquid level height difference is controlled to be ±2 mm.

6. The method for producing aluminum electrolytic capacitor formed foil according to claim 3, characterized in that: The particle size of the nano titanium dioxide is 10-50 nm, and the particle size of the nano aluminum oxide in the nano aluminum oxide dispersion is 20-80 nm.

7. The method for producing aluminum electrolytic capacitor foil according to claim 4, characterized in that: The concentration of sodium gluconate used in the intermediate treatment I is 0.01-0.05wt%, the pH value of the solution is 3.5-4.5, and the immersion process in the intermediate treatment I is carried out under the protection of inert gas.

8. The method for producing aluminum electrolytic capacitor foil according to claim 3 is characterized in that: The frequency of the high-frequency pulse in the third stage of electrolytic oxidation is 2-5 kHz, and the duty cycle is 20%-40%; the particle size of the nano zinc oxide particles is 30-100 nm.

9. The method for producing aluminum electrolytic capacitor formed foil according to claim 4, characterized in that: In the feed slot treatment: the molecular weight of the polyvinyl pyrrolidone is 10,000 to 50,000.

10. The method for producing aluminum electrolytic capacitor formed foil according to claim 4, characterized in that: The gas flow rate of nitrogen protection in the roasting I, roasting II and roasting III is 5 to 15 L / min; The heating rate is 5-10°C / min, and the cooling rate is 8-15°C / min.

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