A preparation process for improving the hydration resistance of low-voltage anode foil

Abstract

The present invention relates to the field of low-voltage anode foil for aluminum electrolytic capacitors, and specifically discloses a preparation process for improving the hydration resistance of low-voltage anode foil. A preparation process for improving the hydration resistance of low-voltage anode foil includes a process flow of 6-stage formation treatment, depolarization treatment (intermediate treatment), roasting treatment and repair formation treatment (post-treatment). The process flow of the prior art is generally 6-stage formation treatment, depolarization treatment (intermediate treatment), post-treatment 1, roasting treatment and repair formation treatment (post-treatment 2). Compared with the prior art, the present application omits the post-treatment 1 step. By omitting this process step, the present application achieves the effect of significantly improving the hydration resistance of the low-voltage anode foil.

Description

Technical Field

[0001] The invention relates to the field of low-voltage anode foil for aluminum electrolytic capacitors, and in particular to a preparation process for improving the hydration resistance of the low-voltage anode foil. Background Art

[0002] Aluminum electrolytic capacitors are generally made of four layers of overlapping winding: anode foil, electrolytic paper, cathode foil, and electrolytic paper. They are an important component widely used in electronic devices, and their performance directly affects the overall performance of electronic devices. Among them, anode foil is roughly divided into low-voltage anode foil (below 200V), medium-voltage anode foil (about 200V), high-voltage anode foil (200-600V) and ultra-high-voltage anode foil (700-900V).

[0003] Low-voltage anode foil is mainly used in miniaturized electronic devices. With the continuous development of electronic devices, the performance requirements for low-voltage anode foil are getting higher and higher. The surface of the low-voltage anode foil is an ultra-thin aluminum oxide film. Existing studies have shown that this aluminum oxide film easily reacts with water to form aluminum hydrate oxide. During the storage and use of aluminum electrolytic capacitors, the low-voltage anode foil will inevitably come into contact with the air and moisture in the working electrolyte. The aluminum oxide film on its surface will react with this moisture to form hydrated oxides, thereby affecting the dielectric properties of the aluminum oxide film, and even causing the aluminum oxide film to lose its dielectric properties, seriously affecting the service life and product quality of the aluminum electrolytic capacitor. Therefore, it is necessary to improve the hydration resistance of the low-voltage anode foil, thereby inhibiting the reaction between the aluminum oxide film and water, thereby extending the service life of the aluminum electrolytic capacitor and improving the product quality of the aluminum electrolytic capacitor. Summary of the invention

[0004] In order to improve the hydration resistance of a low-voltage anode foil used for an aluminum electrolytic capacitor, the present application provides a preparation process for improving the hydration resistance of a low-voltage anode foil.

[0005] The present application provides a preparation process for improving the hydration resistance of low-voltage anode foil using the following technical solutions:

[0006] A preparation process for improving the hydration resistance of a low-voltage anode foil comprises the following steps:

[0007] Step S1, primary conductive roller feeding: taking low voltage corroded aluminum foil, using the conductive roller to directly transmit current to the aluminum foil;

[0008] Step S2, primary chemical treatment: placing the aluminum foil in a primary chemical treatment solution, performing chemical treatment, and obtaining a primary chemically formed aluminum foil;

[0009] Step S3, secondary chemical forming treatment: placing the primary chemical forming aluminum foil into the secondary chemical forming treatment solution, performing chemical forming treatment, and obtaining the secondary chemical forming aluminum foil;

[0010] Step S4, tertiary chemical treatment: placing the secondary chemically formed aluminum foil into a tertiary chemical treatment solution, performing chemical treatment, and obtaining a tertiary chemically formed aluminum foil;

[0011] Step S5, secondary liquid feeding: placing the tertiary formed aluminum foil into an ammonium adipate solution for feeding;

[0012] Step S6, four-stage chemical treatment: placing the aluminum foil that has been fed in the second-stage liquid into the four-stage chemical treatment liquid for chemical treatment to obtain a four-stage chemically formed aluminum foil;

[0013] Step S7, five-level chemical treatment: placing the four-level chemically-formed aluminum foil into the five-level chemically-formed treatment solution, and performing chemical treatment to obtain the five-level chemically-formed aluminum foil;

[0014] Step S8, three-level liquid feeding: placing the five-level formed aluminum foil into the ammonium adipate solution for feeding;

[0015] Step S9, six-level chemical treatment: placing the aluminum foil that has been fed in the three-level liquid into the six-level chemical treatment liquid for chemical treatment to obtain the six-level chemical aluminum foil;

[0016] Step S10, depolarization treatment: after cleaning the six-stage aluminum foil, put it into a 2-10wt% phosphoric acid solution for depolarization treatment to obtain a depolarized aluminum foil;

[0017] Step S11, calcining treatment: calcining the depolarized aluminum foil at a high temperature of 450-500° C. to obtain calcined aluminum foil;

[0018] Step S12, repairing chemical treatment: placing the calcined aluminum foil into a repairing chemical treatment solution for chemical treatment to obtain a repaired chemically formed aluminum foil;

[0019] Step S13, drying treatment: After cleaning the repaired aluminum foil, dry it at 250-300°C.

[0020] In the above technical scheme, the present application obtains a low-voltage anode foil with good hydration resistance through 6-stage chemical formation treatment, depolarization treatment (intermediate treatment), roasting treatment and repair chemical formation treatment (post-treatment). The preparation process of low-voltage anode foil in the prior art generally includes two stages of post-treatment, and the specific process steps are 6-stage chemical formation treatment, depolarization treatment (intermediate treatment), post-treatment 1, roasting treatment and repair chemical formation treatment (post-treatment 2). The present application found in the study that after omitting the process step of post-treatment 1, the aluminum oxide film can be well strengthened and the hydration resistance of the low-voltage anode foil can be improved. This is because after omitting the process step of post-treatment 1, the surface aluminum oxide film of the aluminum foil can obtain a more uniform and dense crystalline aluminum oxide film layer in the subsequent roasting treatment. This aluminum oxide film layer can more effectively block the direct contact between moisture and the internal aluminum oxide film, thereby significantly improving the hydration resistance of the low-voltage anode foil. At the same time, this process improvement also simplifies the preparation process, saves chemical materials and reduces power consumption, reduces manufacturing costs, and improves production efficiency.

[0021] Preferably, the repair chemical treatment solution is a mixed solution of 0.5-1wt% ethylenediaminetetraacetic acid, 0.8-1.2wt% tartaric acid, and 0.5-2wt% sodium silicate. The temperature of the repair chemical treatment is 75-85°C, and the current is 50-100A.

[0022] In the above technical scheme, the present application further limits the repair chemical treatment liquid to a mixed solution of 0.5-1wt% ethylenediaminetetraacetic acid, 0.8-1.2wt% tartaric acid, and 0.5-2wt% sodium silicate, and the temperature range of the repair chemical treatment is 75-85°C, and the current is 50-100A, which further optimizes the repair chemical treatment steps, and can further reduce the boost time of the low-voltage anode foil without affecting the electrostatic capacity of the low-voltage anode foil, thereby further improving the hydration resistance of the low-voltage anode foil. This is because under the specific repair chemical treatment liquid composition and process conditions of the present application, the surface of the aluminum foil can be repaired more finely, and a more uniform and dense protective film layer can be formed. This film can better prevent the aluminum oxide film from absorbing moisture, better improve the hydration resistance of the aluminum oxide film, and maintain its good dielectric properties and stability. At the same time, the appropriate treatment temperature and current range of the present application can ensure the high efficiency and stability of the repair formation treatment process, avoiding the degradation of aluminum foil performance due to over-treatment or the lack of significant improvement in hydration resistance due to insufficient treatment.

[0023] Preferably, the six-stage chemical treatment solution is a mixed solution of 1-5wt% ammonium adipate and 0.8-1.5wt% ammonium carbamate, and the temperature of the six-stage chemical treatment is 75-85°C and the current is 200-600A.

[0024] In the above technical scheme, the present application further improves the effect of the six-stage chemical treatment by further limiting the six-stage chemical treatment liquid to a mixed solution of 1-5wt% ammonium adipate and 0.8-1.5wt% ammonium carbamate, and the temperature range of the six-stage chemical treatment is 75-85°C, and the current is 200-600A. This specific treatment liquid composition and process conditions can ensure that during the chemical treatment process, the aluminum oxide film on the surface of the aluminum foil is uniformly and densely grown to form a more stable aluminum oxide film layer with stronger hydration resistance. At the same time, this treatment liquid composition and process conditions can also effectively reduce impurities and defects on the surface of the aluminum foil, and further improve the dielectric properties and stability of the low-voltage anode foil.

[0025] Preferably, the primary chemical treatment solution is a 3-10wt% ammonium adipate solution, the temperature of the primary chemical treatment is 75-85°C, and the current is 600-1000A.

[0026] Preferably, the secondary chemical formation treatment solution is a 3-10wt% ammonium adipate solution, the temperature of the secondary chemical formation treatment is 75-85°C, and the current is 600-1000A.

[0027] Preferably, the tertiary chemical treatment solution is a 3-10wt% ammonium adipate solution, the temperature of the tertiary chemical treatment is 75-85°C, and the current is 800-1200A.

[0028] Preferably, the quaternary chemical treatment solution is a 3-10wt% ammonium adipate solution, the temperature of the quaternary chemical treatment is 75-85°C, and the current is 800-1200A.

[0029] Preferably, the five-stage chemical treatment solution is a 3-10wt% ammonium adipate solution, the temperature of the five-stage chemical treatment is 75-85°C, and the current is 500-1000A.

[0030] Preferably, the specific operation of the secondary liquid feeding is as follows: at 25-35° C., the tertiary chemically formed aluminum foil is placed in an 8-15wt% ammonium adipate solution, and current is supplied to the aluminum foil in the form of liquid power supply.

[0031] Preferably, the specific operation of the three-stage liquid feeding is as follows: at 25-35° C., the five-stage chemically formed aluminum foil is placed in an 8-15wt% ammonium adipate solution, and current is supplied to the aluminum foil in the form of liquid power supply.

[0032] In the above technical solution, the present application effectively improves the surface structure of the low-voltage anode foil, especially the hydration resistance of the aluminum oxide film of the low-voltage anode foil, through a combination of multi-stage chemical formation treatment and power feeding steps. The present application ensures that the aluminum oxide film on the surface of the aluminum foil grows uniformly and densely by precisely controlling the composition, temperature and current of the treatment solution in each chemical formation treatment step, thereby enhancing its resistance to external moisture.

[0033] In summary, the beneficial technical effects of this application are as follows:

[0034] By omitting the post-processing step 1 in the prior art, the present application not only simplifies the preparation process, but also reduces production costs and improves production efficiency. At the same time, the present application uses a specific repair and chemical treatment process, so that this simplification does not have a negative impact on the electrostatic capacity of the low-voltage anode foil, but further improves the electrostatic capacity and hydration resistance of the low-voltage anode foil, significantly extending the service life of the product. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0036] Examples 1-6

[0037] A preparation process for improving the hydration resistance of a low-voltage anode foil comprises the following steps:

[0038] Step S1, primary conductive roller feeding: taking low voltage corroded aluminum foil, using the conductive roller to directly transmit current to the aluminum foil;

[0039] Step S2, primary chemical treatment: placing the aluminum foil in a primary chemical treatment solution, performing chemical treatment, and obtaining a primary chemically formed aluminum foil;

[0040] Step S3, secondary chemical forming treatment: placing the primary chemical forming aluminum foil into the secondary chemical forming treatment solution, performing chemical forming treatment, and obtaining the secondary chemical forming aluminum foil;

[0041] Step S4, tertiary chemical treatment: placing the secondary chemically formed aluminum foil into a tertiary chemical treatment solution, performing chemical treatment, and obtaining a tertiary chemically formed aluminum foil;

[0042] Step S5, secondary liquid feeding: placing the tertiary formed aluminum foil into an ammonium adipate solution for feeding;

[0043] Step S6, four-stage chemical treatment: placing the aluminum foil that has been fed in the second-stage liquid into the four-stage chemical treatment liquid for chemical treatment to obtain a four-stage chemically formed aluminum foil;

[0044] Step S7, five-level chemical treatment: placing the four-level chemically-formed aluminum foil into the five-level chemically-formed treatment solution, and performing chemical treatment to obtain the five-level chemically-formed aluminum foil;

[0045] Step S8, three-level liquid feeding: placing the five-level formed aluminum foil into the ammonium adipate solution for feeding;

[0046] Step S9, six-level chemical treatment: placing the aluminum foil that has been fed in the three-level liquid into the six-level chemical treatment liquid for chemical treatment to obtain the six-level chemical aluminum foil;

[0047] Step S10, depolarization treatment: after cleaning the six-level aluminum foil, put it into a depolarization treatment solution for depolarization treatment to obtain a depolarized aluminum foil;

[0048] Step S11, calcination treatment: calcining the depolarized aluminum foil at a high temperature to obtain calcined aluminum foil;

[0049] Step S12, repairing chemical treatment: placing the calcined aluminum foil into a repairing chemical treatment solution for chemical treatment to obtain a repaired chemically formed aluminum foil;

[0050] Step S13, drying treatment: cleaning the repaired aluminum foil and drying it.

[0051] The processing steps of each step of Examples 1-6 are shown in Table 1.

[0052] Table 1:

[0053]

[0054]

[0055]

[0056] Comparative Example 1

[0057] A preparation process for low-voltage anode foil with hydration resistance. The difference from Example 6 is that there is a post-treatment step 1 between the depolarization treatment and the calcination treatment. The post-treatment step 1 is specifically as follows: the depolarized aluminum foil obtained by the depolarization treatment is placed in 1.8wt% diammonium phosphate, and under the process conditions of temperature: 85°C, current: 50A, a repairing and forming treatment is performed to obtain a treated aluminum foil.

[0058] Detection

[0059] The various properties of the above-mentioned low-voltage anode foil are tested in accordance with the industry standard SJ / T11140-2022 for electrode foil for aluminum electrolytic capacitors, where L refers to the left side of the electrode foil, C refers to the middle position of the electrode foil, R refers to the right side of the electrode foil, VT60 value refers to the hydration withstand voltage value, and TR60 value refers to the hydration withstand voltage time.

[0060] The above test results are shown in Table 2.

[0061] Table 2:

[0062]

[0063]

[0064] Combining the analysis of Examples 1-6, Comparative Example 1 and Table 2, it is not difficult to see that Examples 1-6 significantly improve the hydration resistance of the low-voltage anode foil, which indicates that the low-voltage anode foil preparation process of the present application has a significant effect on improving the hydration resistance of the low-voltage anode foil.

[0065] According to the comparison between Example 6 and Control Example 1, the post-treatment step 1 is introduced in Control Example 1. Although the electrostatic capacitance of the aluminum foil is improved to a certain extent, its hydration resistance is not significantly improved compared with Example 6. This shows that the present application achieves the effect of significantly improving the hydration resistance of the low-voltage anode foil by reducing the processing steps when preparing the low-voltage anode foil.

[0066] Specifically with respect to Example 1 and Examples 4-6, it is not difficult to see that with the adjustment of the six-level chemical formation treatment liquid and the repair treatment liquid, the electrostatic capacitance of the low-voltage anode foil shows a relatively obvious difference, which indicates that the adjustment of the six-level chemical formation treatment liquid and the repair treatment liquid has an important influence on the electrostatic capacitance of the low-voltage anode foil. The use of the specific six-level chemical formation treatment liquid and the repair treatment liquid of the present application can maintain a good electrostatic capacitance while significantly improving the hydration resistance of the low-voltage anode foil.

[0067] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A preparation process for improving the hydration resistance of low-voltage anode foil, characterized in that: The following steps are involved: Step S1, primary conductive roller feeding: taking low voltage corroded aluminum foil, using the conductive roller to directly transmit current to the aluminum foil; Step S2, primary chemical treatment: placing the aluminum foil in a primary chemical treatment solution, performing chemical treatment, and obtaining a primary chemically formed aluminum foil; Step S3, secondary chemical forming treatment: placing the primary chemical forming aluminum foil into the secondary chemical forming treatment solution, performing chemical forming treatment, and obtaining the secondary chemical forming aluminum foil; Step S4, tertiary chemical treatment: placing the secondary chemically formed aluminum foil into a tertiary chemical treatment solution, performing chemical treatment, and obtaining a tertiary chemically formed aluminum foil; Step S5, secondary liquid feeding: placing the tertiary formed aluminum foil into an ammonium adipate solution for feeding; Step S6, four-stage chemical treatment: placing the aluminum foil that has been fed in the second-stage liquid into the four-stage chemical treatment liquid for chemical treatment to obtain a four-stage chemically formed aluminum foil; Step S7, five-level chemical treatment: placing the four-level chemically-formed aluminum foil into the five-level chemically-formed treatment solution, and performing chemical treatment to obtain the five-level chemically-formed aluminum foil; Step S8, three-level liquid feeding: placing the five-level formed aluminum foil into the ammonium adipate solution for feeding; Step S9, six-level chemical treatment: placing the aluminum foil that has been fed in the three-level liquid into the six-level chemical treatment liquid for chemical treatment to obtain the six-level chemical aluminum foil; Step S10, depolarization treatment: after cleaning the six-stage aluminum foil, put it into a 2-10wt% phosphoric acid solution for depolarization treatment to obtain a depolarized aluminum foil; Step S11, calcining treatment: calcining the depolarized aluminum foil at a high temperature of 450-500° C. to obtain calcined aluminum foil; Step S12, repairing chemical treatment: placing the calcined aluminum foil into a repairing chemical treatment solution for chemical treatment to obtain a repaired chemically formed aluminum foil; Step S13, drying treatment: after cleaning the repaired aluminum foil, drying it at 250-300°C; The repair chemical treatment solution is a mixed solution of 0.5-1wt% ethylenediaminetetraacetic acid, 0.8-1.2wt% tartaric acid, and 0.5-2wt% sodium silicate. The repair chemical treatment temperature is 75-85°C and the current is 50-100A. The six-stage chemical treatment solution is a mixed solution of 1-5wt% ammonium adipate and 0.8-1.5wt% ammonium carbamate. The temperature of the six-stage chemical treatment is 75-85°C and the current is 200-600A.

2. A preparation process for improving the hydration resistance of low-voltage anode foil according to claim 1, characterized in that: The primary chemical treatment liquid is a 3-10wt% ammonium adipate solution, the temperature of the primary chemical treatment is 75-85°C, and the current is 600-1000A.

3. A preparation process for improving the hydration resistance of low-voltage anode foil according to claim 1, characterized in that: The secondary chemical treatment solution is 3-10wt% ammonium adipate solution, the temperature of the secondary chemical treatment is 75-85°C, and the current is 600-1000A.

4. A preparation process for improving the hydration resistance of low-voltage anode foil according to claim 1, characterized in that: The tertiary chemical treatment solution is 3-10wt% ammonium adipate solution, the temperature of the tertiary chemical treatment is 75-85°C, and the current is 800-1200A.

5. The preparation process for improving the hydration resistance of low-voltage anode foil according to claim 1, characterized in that: The quaternary chemical treatment solution is 3-10wt% ammonium adipate solution, the temperature of the quaternary chemical treatment is 75-85°C, and the current is 800-1200A.

6. A preparation process for improving the hydration resistance of low-voltage anode foil according to claim 1, characterized in that: The five-stage chemical treatment solution is a 3-10wt% ammonium adipate solution, the five-stage chemical treatment temperature is 75-85°C, and the current is 500-1000A.

7. A preparation process for improving the hydration resistance of low-voltage anode foil according to claim 1, characterized in that: The specific operation of the secondary liquid feeding is as follows: at 25-35° C., the tertiary chemically formed aluminum foil is placed in an 8-15wt% ammonium adipate solution, and current is supplied to the aluminum foil in the form of liquid power supply.

8. The preparation process for improving the hydration resistance of low-voltage anode foil according to claim 1, characterized in that: The specific operation of the three-stage liquid feeding is as follows: at 25-35° C., the five-stage chemically formed aluminum foil is placed in an 8-15wt% ammonium adipate solution, and current is supplied to the aluminum foil in the form of liquid power supply.

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