JPH0785463B2 - Method for manufacturing electrode foil for aluminum electrolytic capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an electrode foil for an aluminum electrolytic capacitor.

[Prior Art] Generally, this kind of electrode foil is manufactured as follows. First, prepare the etched aluminum foil,
This aluminum foil is immersed in an aqueous solution of phosphoric acid, boric acid or the like, and a certain voltage is applied to perform anodizing treatment (chemical conversion treatment) to form an oxide film having a desired thickness. And
Depolarization treatment and number of immersion in acid or alkali solution
A heat treatment process is performed by leaving it in a high temperature atmosphere of 100 ° C for several minutes. These chemical conversion treatment, depolarization treatment and heat treatment are usually repeated several times.

[Problems to be Solved by the Invention]

However, with this method, there is a limit to increase the electrostatic capacity, and it is not possible to meet the recent demand for smaller size and higher capacity.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing an electrode foil for an aluminum electrolytic capacitor, which is capable of obtaining a higher capacitance.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, in the present invention, the etched aluminum foil is first immersed in high temperature pure water for a predetermined period of time, and then, in an aqueous boric acid solution containing at least an aliphatic saturated dicarboxylic acid or a salt thereof. The aluminum foil is dipped and a voltage is applied for a predetermined time to perform anodization.

In carrying out this chemical conversion, the aluminum foil is first immersed in an aqueous solution of boric acid, and voltage is applied for a predetermined time to carry out the first anodic oxidation, and then the aluminum foil is saturated with an aliphatic saturated dicarboxylic acid or a salt thereof. It is also possible to perform multi-stage anodic oxidation by immersing in an aqueous solution of boric acid containing a and applying a voltage for a predetermined time to perform the second anodic oxidation.
Further, it is also effective to replace the first anodizing step and the second anodizing step described above.

In this case, the aliphatic saturated dicarboxylic acid, XOOC- (CH _{2) n} -COOX formula (wherein, X is H ⁺ or NH ₄ ^+, n = 1~12 preferably n = 1 to 8) Table with Typical examples thereof include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid.

In the present invention, a precursor thereof may be appropriately used instead of the aliphatic saturated dicarboxylic acid or its salt. Examples of precursors in this case include acid amides, esters, and acid anhydrides.

The pH of the aqueous boric acid solution is set to 3 to 9, preferably 4.5 to 7. The concentration of the saturated aliphatic dicarboxylic acid in this boric acid aqueous solution is preferably 0.002 to 1.0%, and the liquid temperature is preferably 70 to 100%.

After the anodizing step, depolarization treatment, heat treatment and re-anodizing treatment are performed at least once. In this case, it is preferable to use an aqueous boric acid solution containing an aliphatic saturated dicarboxylic acid or a salt thereof for the re-anodizing treatment, as in the case of the above-mentioned chemical conversion. According to this, the capacitance is increased by about 5 to 10% or more as compared with the conventional method. For depolarization treatment, ammonia water with a pH of 7 to 9 and a liquid temperature of 50 to 90 ° C (concentration 0.001% to 0.2 wt
%), Or phosphoric acid aqueous solution of pH 4 to 8 (concentration 0.1 to 8 wt%)
Etc. are used, and the immersion time is preferably 1 to 5 minutes.

Example 1 (A) First, an aluminum etching foil having a purity of 99.99% and a thickness of 100 μm was prepared. In this case, the etching rate is for flat (plain) foil not etched.
20 times.

(B) This aluminum etching foil was boiled for 15 minutes in pure water having a liquid temperature of 98 ° C. or higher.

(C) Next, the aluminum etching foil was immersed in a boric acid aqueous solution having a liquid temperature of 85 ° C., in which 20 g of boric acid and 0.1 g of ammonium succinate were added to pure water 1, and a current having a current density of 10 mA / cm ² was applied, The formation voltage was raised to 600 V, and the same voltage was applied for 40 minutes to perform this formation.

(D) The aluminum etching foil after chemical conversion has a liquid temperature of 70 ° C,
Depolarization treatment was carried out by immersing in ammonia water adjusted to pH 7 to 9 for 3 minutes.

(E) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(F) Aqueous solution under the same conditions as (C) above, that is, pure water 1
Immerse again in a boric acid aqueous solution at a liquid temperature of 85 ° C containing 20 g of boric acid and 0.1 g of ammonium succinate to obtain a current density of 10
A current of mA / cm ² was flown to raise the formation voltage to 600 V, and the same voltage was applied for 13 minutes for re-formation.

(G) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(H) Again, it was immersed in pure water 1 containing 20 g of boric acid and 0.1 g of ammonium succinate in a boric acid aqueous solution at a liquid temperature of 85 ° C., and a current having a current density of 10 mA / cm ² was applied to raise the formation voltage to 600 V. The same voltage was applied for 13 minutes for re-formation.

(I) After washing with water and drying, the capacitance of the formed foil was measured and found to be 0.465 μF / cm ² .

(J) This formed foil (15 mm x 270 mm) was used as an anode, while aluminum foil (15 mm x 300 mm) having a purity of 99.2% and a thickness of 20 µm and an etching magnification of 50 times was used as a cathode, and was wound via a separator to form a capacitor element. It was created. Then, when the capacitor element was impregnated with an electrolytic solution and enclosed in a case to prepare an electrolytic capacitor rated at 400 V and 16 μF, its capacitance was 18.5 μF.

In addition, between the above steps (H) and (I), an aqueous solution of 85 wt% phosphoric acid 25 ml / was prepared.
You may intervene the process of performing the immersion treatment for 4 minutes in the aqueous solution adjusted to 30 degreeC of liquid temperature. The electrolytic capacitor to which this step is added can prevent deterioration due to leakage current of the product in a high temperature storage test at 105 ° C. for 1000 hours.

Example 2 (A) An aluminum etching foil having a purity of 99.99% and a thickness of 100 μm was prepared. In this case, the etching magnification is 20 times that of the unetched flat foil.

(B) This aluminum etching foil was boiled for 15 minutes in pure water having a liquid temperature of 98 ° C. or higher.

(C) Next, the aluminum etching foil was immersed in a boric acid aqueous solution having a liquid temperature of 85 ° C., in which 20 g of boric acid and 0.1 g of ammonium adipate were added to pure water 1, and a current having a current density of 10 mA / cm ² was flowed to perform chemical conversion. The voltage was increased to 600 V and the same voltage was applied for 40 minutes to perform this chemical conversion.

(D) The aluminum etching foil after chemical conversion has a liquid temperature of 70 ° C,
Depolarization treatment was carried out by immersing in ammonia water adjusted to pH 7 to 9 for 3 minutes.

(E) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(F) As a re-formation, the pure water 1 was re-immersed in a boric acid aqueous solution at a liquid temperature of 85 ° C in which 20 g of boric acid and 0.1 g of ammonium adipate were added, and a current having a current density of 10 mA / cm ² was applied, and a formation voltage of 600 V was applied. And the same voltage was applied for 13 minutes.

(G) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(H) Again, it was immersed in pure water 1 containing 20 g of boric acid and 0.1 g of ammonium adipate in a boric acid aqueous solution at a liquid temperature of 85 ° C., and a current having a current density of 10 mA / cm ² was passed to raise the formation voltage to 600 V. The same voltage was applied for 13 minutes to perform re-formation.

(I) After washing with water and drying, the capacitance of the formed foil was measured and found to be 0.461 μF / cm ² .

(J) Using this formed foil (15 mm × 270 mm) as an anode, an electrolytic capacitor having a rating of 400 V and 16 μF was prepared in the same manner as in Example 1, and its electrostatic capacity was 18.3 μF.

Example 3 (A) An aluminum etching foil having a purity of 99.99% and a thickness of 100 μm was prepared. In this case, the etching magnification is 20 times that of the unetched flat foil.

(B) This aluminum etching foil was boiled for 15 minutes in pure water having a liquid temperature of 98 ° C. or higher.

(C) Next, the aluminum etching foil is immersed in a boric acid aqueous solution having a liquid temperature of 85 ° C. in which 20 g of boric acid and 0.1 g of ammonium suberate are added to pure water 1 to obtain a current density of 10 mA / cm ²
Current to raise the formation voltage up to 600V,
This chemical conversion was performed by applying for a minute.

(D) The aluminum etching foil after chemical conversion has a liquid temperature of 70 ° C,
Depolarization treatment was carried out by immersing in ammonia water adjusted to pH 7 to 9 for 3 minutes.

(E) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(F) As a re-formation, the pure water 1 was re-immersed in a boric acid aqueous solution at a liquid temperature of 85 ° C in which 20 g of boric acid and 0.1 g of ammonium suberate were added, and a current having a current density of 10 mA / cm ² was applied, and a formation voltage of 600 V was applied. And the same voltage was applied for 13 minutes.

(G) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(H) Again, it was immersed in pure water 1 containing 20 g of boric acid and 0.1 g of ammonium suberate in a boric acid aqueous solution at a liquid temperature of 85 ° C., and a current having a current density of 10 mA / cm ² was applied to raise the formation voltage to 600 V. The same voltage was applied for 13 minutes to perform re-formation.

(I) After washing with water and drying, the capacitance of the formed foil was measured and found to be 0.444 μF / cm ² .

(J) Using this formed foil (15 mm × 270 mm) as an anode, an electrolytic capacitor having a rating of 400 V and 16 μF was prepared in the same manner as in Example 1, and the electrostatic capacity was 17.6 μF.

Example 4 (A) An aluminum etching foil having a purity of 99.99% and a thickness of 100 μm was prepared. In this case, the etching magnification is 20 times that of the unetched flat foil.

(B) This aluminum etching foil was boiled for 15 minutes in pure water having a liquid temperature of 98 ° C. or higher.

(C) Next, the aluminum etching foil was immersed in a boric acid aqueous solution having a liquid temperature of 85 ° C. in which 20 g of boric acid and 0.1 g of ammonium sebacate were added to pure water 1 to obtain a current density of 10 mA / cm ^2.
Current to raise the formation voltage up to 600V,
This chemical conversion was performed by applying for a minute.

(D) The aluminum etching foil after chemical conversion has a liquid temperature of 70 ° C,
It was immersed in a phosphoric acid aqueous solution adjusted to 3.5 wt% for 3 minutes for depolarization treatment.

(E) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(F) As re-formation, it is again immersed in a boric acid aqueous solution at a liquid temperature of 85 ° C in which 20 g of boric acid and 0.1 g of ammonium sebacate are added to pure water 1, and a current having a current density of 10 mA / cm ² is flowed to form a formation voltage of 600 V. And the same voltage was applied for 13 minutes.

(G) Heat treatment was performed for 2 minutes in a heating atmosphere of 500 ° C.

(H) Again, it was immersed in pure water 1 containing 20 g of boric acid and 0.1 g of ammonium sebacate in an aqueous solution of boric acid at a liquid temperature of 85 ° C., and a current having a current density of 10 mA / cm ² was passed to raise the formation voltage to 600 V. The same voltage was applied for 13 minutes to perform re-formation.

(I) After washing with water and drying, the capacitance of the formed foil was measured and found to be 0.463 μF / cm ² .

(J) When this formed foil (15 mm × 270 mm) was used as an anode, an electrolytic capacitor having a rating of 400 V and 16 μF was prepared in the same manner as in Example 1. Its electrostatic capacity was 18.4 μF.

Comparative Example 1 (a) An aluminum etching foil having a purity of 99.99% and a thickness of 100 μm was prepared. In this case, the etching magnification is 20 times that of a non-etched flat foil.

(B) The aluminum etching foil was boiled for 15 minutes in pure water having a liquid temperature of 98 ° C or higher.

(C) An aqueous solution prepared by adding 20 g of boric acid to pure water 1 at a liquid temperature of 85 ° C.
Immerse aluminum etching foil in it, current density 10mA
A current of / cm ² was passed to raise the formation voltage to 600 V, and the same voltage was applied for 40 minutes to perform the main formation.

(D) Liquid temperature of the aluminum etching foil after chemical conversion is 70 ° C,
Depolarization treatment was carried out by immersing in ammonia water adjusted to pH 7 to 9 for 3 minutes.

(E) Heat treatment was performed for 2 minutes in a heating atmosphere at 500 ° C.

(F) As a re-formation, the solution was re-immersed in an aqueous solution containing 20 g of boric acid added to pure water 1 at a liquid temperature of 85 ° C., a current density of 10 mA / cm ² was applied, and the formation voltage was increased to 600 V, and the same voltage was adjusted to 13 V. It was applied for a minute.

(G) Heat treatment was performed in a heating atmosphere of 500 ° C. for 2 minutes.

(H) Again, it was immersed in an aqueous solution of 20 g of boric acid added to pure water 1 at a liquid temperature of 85 ° C., a current density of 10 mA / cm ² was applied, the formation voltage was increased to 600 V, and the same voltage was applied for 13 minutes. Was reformed.

(I) After washing with water and drying, the capacitance of the formed foil was measured and found to be 0.296 μF / cm ² .

(J) When this formed foil (15 mm × 270 mm) was used as an anode to prepare an electrolytic capacitor rated at 400 V and 16 μF as in Example 1, the electrostatic capacity was 11.7 μF.

Comparative Example 2 (a) An aluminum etching foil having a purity of 99.99% and a thickness of 100 μm was prepared. In this case, the etching magnification is 20 times that of the unetched flat foil.

(B) The aluminum etching foil was boiled for 15 minutes in pure water having a liquid temperature of 98 ° C or higher.

(C) 20 g of boric acid and 0.5 of ammonium borate in pure water 1
The aluminum etching foil was dipped in an aqueous solution containing 85 g and a liquid temperature of 85 ° C., a current density of 10 mA / cm ² was applied to increase the formation voltage to 600 V, and the same voltage was applied for 40 minutes to perform the main formation.

(D) Liquid temperature of the aluminum etching foil after chemical conversion is 70 ° C,
Depolarization treatment was carried out by immersing in ammonia water adjusted to pH 7 to 9 for 3 minutes.

(E) Heat treatment was performed for 2 minutes in a heating atmosphere at 500 ° C.

(F) For re-formation, re-immerse in pure water 1 in an aqueous solution containing 20 g of boric acid and 0.5 g of ammonium borate and a liquid temperature of 85 ° C., and apply a current having a current density of 10 mA / cm ² to raise the formation voltage to 600 V. The same voltage was applied for 13 minutes.

(G) Heat treatment was performed in a heating atmosphere of 500 ° C. for 2 minutes.

(H) Again, it was immersed in an aqueous solution of 20 g of boric acid and 0.5 g of ammonium borate added to pure water 1 at a liquid temperature of 85 ° C., a current density of 10 mA / cm ² was applied, and the formation voltage was increased to 600 V, The voltage was applied for 13 minutes for re-formation.

(I) It was washed with water and dried, and the capacitance of the formed foil was measured and found to be 0.423 μF / cm ² .

(J) When this formed foil (15 mm × 270 mm) was used as an anode, an electrolytic capacitor having a rating of 400 V and 16 μF was prepared in the same manner as in Example 1. Its electrostatic capacity was 16.8 μF.

For reference, the following table shows the capacitance of the chemical conversion foil obtained in each of the examples and the comparative examples and the capacitance of the electrolytic capacitor prototyped using the chemical conversion foil.

As is clear from this table, according to the present invention, both the capacitance of the foil and the capacitance of the product are increased by about 5 to 10% as compared with the comparative example by the conventional method.

〔The invention's effect〕

As described above, according to the present invention, the etched aluminum foil is boiled with pure water, and then the aluminum foil is immersed in a boric acid solution containing an aliphatic saturated dicarboxylic acid or a salt thereof, and a voltage is applied for a predetermined time. By carrying out the anodic oxidation, an electrode foil having a high capacitance is manufactured.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Endo 2-2-1 Tsujido Shinmachi, Fujisawa City, Kanagawa Elner Co., Ltd. (72) Inventor Noboru Haga 2-2-1 Tsujido Shinmachi, Fujisawa City, Kanagawa Elner Co., Ltd. (72) Inventor Mikio Sasaki 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Asahi Glass Co., Ltd.

Claims (5)

[Claims] 1. A pure water boiling step of immersing the etched aluminum foil in high temperature pure water for a predetermined time, and then immersing the aluminum foil in a boric acid aqueous solution containing at least an aliphatic saturated dicarboxylic acid or a salt thereof. And an anodizing step of applying a voltage for a predetermined time. A method of manufacturing an electrode foil for an aluminum electrolytic capacitor, comprising: 2. The aliphatic saturated dicarboxylic acid comprises a compound represented by the chemical formula XOOC- (CH ₂ ) _n -COOX (where X is H ⁺ or NH ₄ ⁺ , n = 1 to 12). Item 2. A method for producing an electrode foil for an aluminum electrolytic capacitor according to Item 1. 3. The method for producing an electrode foil for an aluminum electrolytic capacitor according to claim 1, wherein the pH of the aqueous boric acid solution is 3 to 9. 4. The concentration of the saturated aliphatic dicarboxylic acid in the aqueous boric acid solution is 0.002 to 1.0%, and the liquid temperature is 70 to 100 ° C.
The method for manufacturing an electrode foil for an aluminum electrolytic capacitor according to claim 1. 5. A depolarizing treatment, a heat treatment and a reanodizing treatment are carried out at least once after the anodizing step according to claim 1, and the reanodizing treatment comprises boric acid containing an aliphatic saturated dicarboxylic acid or a salt thereof. A method for manufacturing an electrode foil for an aluminum electrolytic capacitor using an aqueous solution.