Preparation method of high-water-resistance aluminum anode foil

Abstract

The invention belongs to the technical field of anode foil manufacturing, and particularly relates to a preparation method of a high-water-resistance aluminum anode foil. In order to solve the problem that in the prior art, water resistance and leakage current reverse side performance are not ideal enough, the preparation method of the high-water-resistance aluminum anode foil is provided and comprises the steps that a formed foil is soaked in an acid solution and then washed with deionized water, and the washed formed foil is obtained; performing heat treatment to obtain a heat-treated formed foil; soaking the foil in pure water, cleaning the foil with deionized water, and performing heat treatment after cleaning to obtain a secondary heat-treated formed foil; and soaking in a treating fluid containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 5-10 minutes, then cleaning with deionized water, and drying in a drying oven to obtain the high-water-resistance aluminum anode foil. According to the invention, on the basis of the existing formed aluminum foil, further treatment is carried out, so that the water resistance of the formed aluminum foil is improved, the leakage current of the formed aluminum foil is reduced, the operation steps are simple, and the production cost is relatively low.

Description

Technical Field

[0001] The invention belongs to the technical field of anode foil manufacturing, and in particular relates to a method for preparing a highly water-resistant aluminum anode foil. Background Art

[0002] At present, aluminum electrolytic capacitors are widely used in various fields. Aluminum anode foil (chemical foil) is a key component of aluminum electrolytic capacitors. Aluminum can form an oxide film after anodization, but the water resistance and corrosion resistance of this oxide film are not ideal, which is manifested in that the leakage current of the aluminum anode foil is large and the boost time is long. The results of electron microscopy show that this is due to the presence of holes on the surface of the oxide film after its surface is formed, which is not completely dense. Therefore, how to further process the chemical foil in the prior art in order to improve its water resistance, thereby reducing the leakage current while ensuring production efficiency and increasing the service life of the capacitor has become a technical problem that needs to be solved urgently.

[0003] In response to this problem, people have also conducted exploration and research in long-term production and life practices. For example, a Chinese invention patent discloses a chemical treatment method for high water-resistant low-pressure aluminum foil [application number: 202010504840.7]. The invention includes the following steps: (1) Pretreatment: placing the corroded foil in an ammonium adipate solution for pre-chemical treatment; (2) Chemical treatment: placing the aluminum foil treated in step (1) in an ammonium adipate solution with a temperature of 50-90°C and a concentration of 50-90g / L, setting the DC power supply current density to 50-200mA / cm, increasing the voltage step by step, and performing four-stage chemical treatment. During the anodizing process, an ultrasonic vibration plate also placed in the solution is vibrated at a fixed frequency, the frequency of the ultrasonic vibration plate is 20-100kHz, the ultrasonic vibration plate each ultrasonic duration is 5-60s, and the ultrasonic interval is 10-60s; (3) Passivation treatment: placing the aluminum foil treated in step (2) at a temperature of The aluminum foil treated in step (3) is placed in a mixed solution of ammonium adipate and diammonium phosphate at a temperature of 70-95°C, wherein the concentration of ammonium adipate is 10-50 g / L and the concentration of diammonium phosphate is 1-10 g / L, and a current of 5-15 mA / cm is applied to perform a re-forming; (5) heat treatment is performed on the aluminum foil. Treatment: placing the aluminum foil treated in step (4) in a microwave heating device for rapid annealing, the power of the microwave heating device is 20-60 kW, and the microwave heating time is 30-120 s; (6) secondary re-forming: placing the aluminum foil treated in step (5) in a diammonium phosphate solution with a temperature of 70-95° C. and a concentration of 2-12 g / L, applying a current of 5-15 mA / cm, and performing secondary re-forming, and finally obtaining a low-voltage anode aluminum foil with high water resistance.

[0004] Although the invention improves the hydration resistance of the aluminum foil by 50%-80%, it adopts a technical solution of improving the relevant chemical formation process, which has complicated operation steps and high cost, and is not suitable for popularization and use. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a highly water-resistant aluminum anode foil in view of the above problems.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a highly water-resistant aluminum anode foil comprises the following steps:

[0008] Step 1: Soaking the formed foil in an acid solution, and then washing it with deionized water to obtain a washed formed foil;

[0009] Step 2: heat-treating the washed chemical foil obtained in step 1 to obtain a heat-treated chemical foil;

[0010] Step 3: soaking the heat-treated foil obtained in step 2 in pure water, washing it with deionized water, and then heat-treating it again after washing to obtain a secondary heat-treated foil;

[0011] Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 5-10 minutes, then wash it with deionized water and dry it in an oven to obtain a highly water-resistant aluminum anode foil.

[0012] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, the treatment liquid includes 1-8 parts by mass of nickel acetate, 2-10 parts by mass of cobalt acetate, 3-12 parts by mass of sodium silicate, 1-12 parts by mass of ammonia water, 2-10 parts by mass of potassium dichromate, 4-15 parts by mass of triethanolamine and 80-100 parts by mass of water.

[0013] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, the treatment liquid includes 5 parts by mass of nickel acetate, 6 parts by mass of cobalt acetate, 8 parts by mass of sodium silicate, 6 parts by mass of ammonia water, 6 parts by mass of potassium dichromate, 10 parts by mass of triethanolamine and 90 parts by mass of water.

[0014] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, the acidic solution in step 1 is a potassium dihydrogen phosphate aqueous solution, and the mass fraction of the potassium dihydrogen phosphate is 1%-8%.

[0015] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, the soaking time of the acid solution in step 1 is 2-20 minutes and the temperature is 60-80°C.

[0016] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, the heat treatment method of step two and step three is: preheating the high-temperature furnace to above 500°C, and then placing the formed foil in the high-temperature furnace, the temperature of the high-temperature furnace is controlled at 480-520°C, and the heating time is 60-300s.

[0017] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, the pure water temperature in step three is 80-100° C., and the soaking time is 3-15 min.

[0018] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, the temperature of the treatment solution in step 4 is 60-80°C.

[0019] In the above-mentioned method for preparing a highly water-resistant aluminum anode foil, in step 4, the oven temperature is 180-220° C., and the drying time is 2-5 min.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] 1. The present invention provides a method for further processing the formed aluminum foil after the existing formation to improve its water resistance and reduce its leakage current. The operation steps are simple, the production cost is low, and it is suitable for large-scale promotion and use.

[0022] 2. The present invention uses an aqueous solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine as a treatment liquid. The components have a certain synergistic effect in promoting membrane conversion, making the membrane conversion process more efficient. At the same time, the treatment liquid has a lower solubility in the aluminum oxide film and can better promote the formation of a barrier-type (dense) oxide film, thereby reducing the porosity of the aluminum oxide film and improving electrical insulation. The dense porous aluminum oxide film formed is more uniform and reasonable in terms of pore structure and pore size distribution, so that it has better capacitance performance in subsequent applications (such as when used as a dielectric layer in a capacitor). DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with specific implementation methods.

[0024] Example 1

[0025] This embodiment provides a method for preparing a highly water-resistant aluminum anode foil, comprising the following steps:

[0026] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 2 minutes at a temperature of 60° C., with a mass fraction of potassium dihydrogen phosphate of 1%, and then washing with deionized water to obtain a rinsed formed foil;

[0027] Step 2: heat-treating the washed chemical foil obtained in step 1. The heat-treating method is to preheat a high-temperature furnace to 500° C., and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 480° C., and the heating time is 60 seconds to obtain a heat-treated chemical foil.

[0028] Step 3: Soak the heat-treated chemical foil obtained in step 2 in pure water at 80°C for 3 minutes, wash it with deionized water, and then perform heat treatment after washing. The heat treatment method is to preheat the high-temperature furnace to 500°C, and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 480°C, and the heating time is 60s to obtain a secondary heat-treated chemical foil;

[0029] Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 5 minutes at a temperature of 60°C, then wash with deionized water, and dry in an oven at a temperature of 180°C for 2 minutes to obtain a highly water-resistant aluminum anode foil.

[0030] The treatment liquid includes 1 part of nickel acetate, 10 parts of cobalt acetate, 12 parts of sodium silicate, 12 parts of ammonia water, 10 parts of potassium dichromate, 15 parts of triethanolamine and 100 parts of water in respective weight proportions.

[0031] Example 2

[0032] This embodiment provides a method for preparing a highly water-resistant aluminum anode foil, comprising the following steps:

[0033] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 20 minutes at a temperature of 80° C., with a mass fraction of potassium dihydrogen phosphate of 8%, and then washing with deionized water to obtain a washed formed foil;

[0034] Step 2: heat-treating the washed chemical foil obtained in step 1. The heat-treating method is to preheat a high-temperature furnace to 500° C., and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 520° C., and the heating time is 300 seconds to obtain a heat-treated chemical foil.

[0035] Step 3: Soak the heat-treated chemical foil obtained in step 2 in pure water at 100° C. for 15 minutes, wash it with deionized water, and then perform heat treatment after washing. The heat treatment method is to preheat the high-temperature furnace to 500° C., then place the chemical foil in the high-temperature furnace, control the temperature of the high-temperature furnace at 520° C., and heat for 300 seconds to obtain a secondary heat-treated chemical foil;

[0036] Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 10 minutes at a temperature of 80°C, then wash with deionized water, and dry in an oven at a temperature of 220°C for 5 minutes to obtain a highly water-resistant aluminum anode foil.

[0037] The treatment liquid includes 8 parts by weight of nickel acetate, 2 parts by weight of cobalt acetate, 3 parts by weight of sodium silicate, 1 part by weight of ammonia water, 2 parts by weight of potassium dichromate, 4 parts by weight of triethanolamine and 80 parts by weight of water.

[0038] Example 3

[0039] This embodiment provides a method for preparing a highly water-resistant aluminum anode foil, comprising the following steps:

[0040] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 5 minutes at a temperature of 70° C., with a mass fraction of potassium dihydrogen phosphate of 3%, and then washing with deionized water to obtain a rinsed formed foil;

[0041] Step 2: heat-treating the washed chemical foil obtained in step 1. The heat-treating method is to preheat a high-temperature furnace to 500° C., and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 500° C., and the heating time is 100 seconds to obtain a heat-treated chemical foil.

[0042] Step 3: Soak the heat-treated chemical foil obtained in step 2 in pure water at 90° C. for 4 minutes, wash it with deionized water, and then perform heat treatment after washing. The heat treatment method is to preheat the high-temperature furnace to 500° C., then place the chemical foil in the high-temperature furnace, control the temperature of the high-temperature furnace at 500° C., and heat for 100 seconds to obtain a secondary heat-treated chemical foil;

[0043] Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 8 minutes at a temperature of 70°C, then wash with deionized water, and dry in an oven at a temperature of 200°C for 3.5 minutes to obtain a highly water-resistant aluminum anode foil.

[0044] The treatment liquid includes 5 parts by weight of nickel acetate, 6 parts by weight of cobalt acetate, 8 parts by weight of sodium silicate, 6 parts by weight of ammonia water, 6 parts by weight of potassium dichromate, 10 parts by weight of triethanolamine and 90 parts by weight of water.

[0045] Comparative Example 1

[0046] This comparative example provides a method for preparing an aluminum anode foil, comprising the following steps:

[0047] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 5 minutes at a temperature of 70° C., with a mass fraction of potassium dihydrogen phosphate of 3%, and then washing with deionized water to obtain a rinsed formed foil;

[0048] Step 2: Soak the chemical foil obtained in step 1 in pure water at 90° C. for 4 minutes, wash it with deionized water, and then perform heat treatment after washing. The heat treatment method is to preheat the high-temperature furnace to 500° C., then place the chemical foil in the high-temperature furnace, control the temperature of the high-temperature furnace at 500° C., and heat for 100 seconds to obtain a heat-treated chemical foil;

[0049] Step 4: Soak the heat-treated foil obtained in step 3 in a treatment solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 8 minutes at a temperature of 70°C, then wash with deionized water, and dry in an oven at a temperature of 200°C for 3.5 minutes to obtain a highly water-resistant aluminum anode foil.

[0050] The treatment liquid includes 5 parts by weight of nickel acetate, 6 parts by weight of cobalt acetate, 8 parts by weight of sodium silicate, 6 parts by weight of ammonia water, 6 parts by weight of potassium dichromate, 10 parts by weight of triethanolamine and 90 parts by weight of water.

[0051] Comparative Example 2

[0052] This comparative example provides a method for preparing an aluminum anode foil, comprising the following steps:

[0053] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 5 minutes at a temperature of 70° C., with a mass fraction of potassium dihydrogen phosphate of 3%, and then washing with deionized water to obtain a rinsed formed foil;

[0054] Step 2: heat-treating the washed chemical foil obtained in step 1. The heat-treating method is to preheat a high-temperature furnace to 500° C., and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 500° C., and the heating time is 100 seconds to obtain a heat-treated chemical foil.

[0055] Step 3: Soak the heat-treated foil obtained in step 2 in pure water at 90°C for 4 minutes, then wash it with deionized water, and then soak it in a treatment solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 8 minutes at a temperature of 70°C. Then wash it with deionized water and dry it in an oven at a temperature of 200°C for 3.5 minutes to obtain a highly water-resistant aluminum anode foil.

[0056] The treatment liquid includes 5 parts by weight of nickel acetate, 6 parts by weight of cobalt acetate, 8 parts by weight of sodium silicate, 6 parts by weight of ammonia water, 6 parts by weight of potassium dichromate, 10 parts by weight of triethanolamine and 90 parts by weight of water.

[0057] Comparative Example 3

[0058] This comparative example provides a method for preparing an aluminum anode foil, comprising the following steps:

[0059] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 5 minutes at a temperature of 70° C., with a mass fraction of potassium dihydrogen phosphate of 3%, and then washing with deionized water to obtain a rinsed formed foil;

[0060] Step 2: heat-treating the washed chemical foil obtained in step 1. The heat-treating method is to preheat a high-temperature furnace to 500° C., and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 500° C., and the heating time is 100 seconds to obtain a heat-treated chemical foil.

[0061] Step 3: Soak the heat-treated chemical foil obtained in step 2 in pure water at 90° C. for 4 minutes, wash it with deionized water, and then perform heat treatment after washing. The heat treatment method is to preheat the high-temperature furnace to 500° C., then place the chemical foil in the high-temperature furnace, control the temperature of the high-temperature furnace at 500° C., and heat for 100 seconds to obtain a secondary heat-treated chemical foil;

[0062] Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution for 8 minutes at a temperature of 70°C, then wash with deionized water, and dry in an oven at a temperature of 200°C for 3.5 minutes to obtain a highly water-resistant aluminum anode foil.

[0063] Wherein, the treatment liquid includes water.

[0064] Comparative Example 4

[0065] This comparative example provides a method for preparing an aluminum anode foil, comprising the following steps:

[0066] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 5 minutes at a temperature of 70° C., with a mass fraction of potassium dihydrogen phosphate of 3%, and then washing with deionized water to obtain a rinsed formed foil;

[0067] Step 2: heat-treating the washed chemical foil obtained in step 1. The heat-treating method is to preheat a high-temperature furnace to 500° C., and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 500° C., and the heating time is 100 seconds to obtain a heat-treated chemical foil.

[0068] Step 3: Soak the heat-treated chemical foil obtained in step 2 in pure water at 90° C. for 4 minutes, wash it with deionized water, and then perform heat treatment after washing. The heat treatment method is to preheat the high-temperature furnace to 500° C., then place the chemical foil in the high-temperature furnace, control the temperature of the high-temperature furnace at 500° C., and heat for 100 seconds to obtain a secondary heat-treated chemical foil;

[0069] Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution for 8 minutes at a temperature of 70°C, then wash with deionized water, and dry in an oven at a temperature of 200°C for 3.5 minutes to obtain a highly water-resistant aluminum anode foil.

[0070] The treatment liquid includes 5 parts by mass of nickel acetate, 6 parts by mass of cobalt acetate, 6 parts by mass of potassium dichromate and 90 parts by mass of water.

[0071] Comparative Example 5

[0072] This comparative example provides a method for preparing an aluminum anode foil, comprising the following steps:

[0073] Step 1: soaking the formed foil in a potassium dihydrogen phosphate aqueous solution for 5 minutes at a temperature of 70° C., with a mass fraction of potassium dihydrogen phosphate of 3%, and then washing with deionized water to obtain a rinsed formed foil;

[0074] Step 2: heat-treating the washed chemical foil obtained in step 1. The heat-treating method is to preheat a high-temperature furnace to 500° C., and then place the chemical foil in the high-temperature furnace. The temperature of the high-temperature furnace is controlled at 500° C., and the heating time is 100 seconds to obtain a heat-treated chemical foil.

[0075] Step 3: Soak the heat-treated chemical foil obtained in step 2 in pure water at 90° C. for 4 minutes, wash it with deionized water, and then perform heat treatment after washing. The heat treatment method is to preheat the high-temperature furnace to 500° C., then place the chemical foil in the high-temperature furnace, control the temperature of the high-temperature furnace at 500° C., and heat for 100 seconds to obtain a secondary heat-treated chemical foil;

[0076] Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution for 8 minutes at a temperature of 70°C, then wash with deionized water, and dry in an oven at a temperature of 200°C for 3.5 minutes to obtain a highly water-resistant aluminum anode foil.

[0077] The treatment liquid includes 8 parts by weight of sodium silicate, 6 parts by weight of ammonia water, 10 parts by weight of triethanolamine and 90 parts by weight of water.

[0078] Application Example 1

[0079] The chemically formed foil produced in the same batch was cut into six pieces of the same size and thickness, and the preparation methods described in Example 3 and Comparative Examples 1-5 were used to prepare high water-resistant aluminum anode foils 1-6. The relevant properties of the high water-resistant aluminum anode foils 1-6 were tested, and the results are shown in the following table:

[0080]

[0081]

[0082] Result analysis: It can be seen from the above experimental results that the highly water-resistant aluminum anode foil provided by the present invention has the lowest leakage current and the shortest voltage rise time, thus achieving the intended purpose of the present invention.

[0083] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A method for preparing a highly water-resistant aluminum anode foil, characterized in that: The following steps are involved: Step 1: Soaking the formed foil in an acid solution, and then washing it with deionized water to obtain a washed formed foil; Step 2: heat-treating the washed chemical foil obtained in step 1 to obtain a heat-treated chemical foil; Step 3: soaking the heat-treated foil obtained in step 2 in pure water, washing it with deionized water, and then heat-treating it again after washing to obtain a secondary heat-treated foil; Step 4: Soak the secondary heat-treated foil obtained in step 3 in a treatment solution containing nickel acetate, cobalt acetate, sodium silicate, ammonia, potassium dichromate and triethanolamine for 5-10 minutes, then wash it with deionized water and dry it in an oven to obtain a highly water-resistant aluminum anode foil.

2. The method for preparing a highly water-resistant aluminum anode foil according to claim 1, characterized in that: The treatment liquid comprises 1-8 parts by weight of nickel acetate, 2-10 parts by weight of cobalt acetate, 3-12 parts by weight of sodium silicate, 1-12 parts by weight of ammonia water, 2-10 parts by weight of potassium dichromate, 4-15 parts by weight of triethanolamine and 80-100 parts by weight of water.

3. The method for preparing a highly water-resistant aluminum anode foil according to claim 2, characterized in that: The treatment liquid comprises 5 parts by mass of nickel acetate, 6 parts by mass of cobalt acetate, 8 parts by mass of sodium silicate, 6 parts by mass of ammonia water, 6 parts by mass of potassium dichromate, 10 parts by mass of triethanolamine and 90 parts by mass of water.

4. The method for preparing a highly water-resistant aluminum anode foil according to claim 1, characterized in that: The acidic solution in step 1 is a potassium dihydrogen phosphate aqueous solution, and the mass fraction of potassium dihydrogen phosphate is 1%-8%.

5. The method for preparing a highly water-resistant aluminum anode foil according to claim 1, characterized in that: The soaking time of the acid solution in step 1 is 2-20 minutes, and the temperature is 60-80°C.

6. The method for preparing a highly water-resistant aluminum anode foil according to claim 1, characterized in that: The heat treatment method of step 2 and step 3 is: preheat the high temperature furnace to above 500° C., then place the formed foil in the high temperature furnace, control the temperature of the high temperature furnace at 480-520° C., and heat for 60-300 seconds.

7. The method for preparing a highly water-resistant aluminum anode foil according to claim 1, characterized in that: In step 3, the pure water temperature is 80-100° C., and the soaking time is 3-15 minutes.

8. The method for preparing a highly water-resistant aluminum anode foil according to claim 1, characterized in that: The temperature of the treatment liquid in step 4 is 60-80°C.

9. The method for preparing a highly water-resistant aluminum anode foil according to claim 1, characterized in that: In step 4, the oven temperature is 180-220° C. and the drying time is 2-5 min.

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