JP3853432B2

JP3853432B2 - Method for producing electrode foil for aluminum electrolytic capacitor

Info

Publication number: JP3853432B2
Application number: JP18631796A
Authority: JP
Inventors: 毅一別所
Original assignee: Nichicon Capacitor Ltd
Current assignee: Nichicon Capacitor Ltd
Priority date: 1996-07-16
Filing date: 1996-07-16
Publication date: 2006-12-06
Anticipated expiration: 2016-07-16
Also published as: JPH1032146A

Description

【０００１】
【発明の属する技術分野】
本発明は、アルミニウム電解コンデンサ用電極箔の製造方法に関するものである。
【０００２】
【従来の技術】
従来のアルミニウム電解コンデンサは、エッチング処理により実効表面積を拡大させたアルミニウム箔に、化成処理を施し、表面に誘電体となる陽極酸化皮膜を形成した陽極箔と、陰極箔との間にセパレータを介して巻回してなるコンデンサ素子に駆動用電解液を含浸させ、ケースに挿入し封止することにより構成されていた。
【０００３】
上記アルミニウム箔に陽極酸化皮膜を形成させる化成工程は、次のような手順により行っていた。すなわち、エッチング処理により実効表面積を拡大させたアルミニウム箔を、硼酸、リン酸、アジピン酸、クエン酸、またはそれら塩の水溶液中にて定電流で化成を行い、所定の化成電圧到達後、定電圧にて一定時間保持し第１段化成を終了する。なお、使用電圧または用途により第一段化成の前に化学処理による皮膜形成工程を行うこともある。
【０００４】
次に、第１段化成にて生成した陽極酸化皮膜中の欠陥等を取り除くために、生成した陽極酸化皮膜の一部を溶解処理または熱処理等による減極処理を行い、再度陽極酸化による修復化成を行う。この工程は必要により繰り返されることがある。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記の従来化成工程においては、化成電圧が高いほど第１段化成にて陽極酸化皮膜中の欠陥が増加し、化成箔特性を維持するために減極処理条件を厳しくする必要があり、その結果修復化成における電気量が増加するという問題があった。
【０００６】
【課題を解決するための手段】
本発明は上記の従来の事情に鑑み、各種検討した結果見いだされたものであり、陽極酸化皮膜を形成する工程のうち、減極処理後の修復化成工程に着目し、減極処理後に化学処理による皮膜生成工程を設けることにより、電気量の低減を図り、かつ特性の優れた化成箔を提供することを特徴としている。
【０００７】
表面を粗面化し、実効表面積を拡大させたアルミニウム箔を化成して、陽極酸化皮膜を形成するアルミニウム電解コンデンサ用陽極箔の製造方法において、
該アルミニウム箔を化成耐電圧１６０Ｖ以下で化成する場合に、化成工程で減極処理後、下記（１）〜（３）の化学処理液、
（１）液温４０〜６０℃の純水・イオン交換水、
（２）液温４０〜６０℃、ｐＨ９〜１２のアルミン酸塩水溶液、
（３）液温８０〜１００℃、ｐＨ１０〜１３の珪酸塩水溶液
による化学処理にて皮膜を形成し、熱処理を行った後、陽極酸化皮膜を形成することを特徴とするアルミニウム電解コンデンサ用電極箔の製造方法である。
【０００８】
【作用】
減極処理後に、上記（１）〜（３）の液による化学処理を行うことにより、形成される皮膜は各々、下記（１）、（２）の作用を有する。
【０００９】
（１）浸漬処理温度：４０〜６０℃、化成耐電圧：１６０Ｖ以下
ａ）減極処理後、４０〜６０℃の純水またはイオン交換水にて化学処理後、熱処理を行うことにより、露呈した欠陥に生成した水和皮膜が疑似ベーマイト皮膜となり、修復化成が容易に行われるため、化成電気量の低減が図れ、かつ特性の優れた化成箔を得ることができる。
ｂ）減極処理後、ｐＨ９〜１２のアルミン酸塩水溶液に、処理温度４０〜６０℃にて浸漬し、生成する水和皮膜を熱処理することにより疑似ベーマイト皮膜を生成させ、この疑似ベーマイト皮膜を利用して修復化成が容易に行われるため、化成電気量の低減が図れ、かつ特性の優れた化成箔を得ることができる。
【００１０】
（２）浸漬処理温度：８０〜１００℃、化成耐電圧：１６０Ｖ以下、
ｐＨ１０〜１３の珪酸塩水溶液に、処理温度８０〜１００℃で浸漬した後、熱処理を行うことにより、保護皮膜が形成され、修復化成時に生成する皮膜中に化成液中のイオンが侵入することを防止するので、皮膜の結晶化が進み易くなり、化成電気量の低減が図れ、かつ特性の優れた化成箔を得ることができる。
【００１２】
本発明の実施例と従来例を下記の表１の記載に基づき説明する。なお、アジピン酸系化成液とは液温７０℃の５重量％アジピン酸アンモニウム水溶液であり、リン酸系化成液とは液温８５℃の０．１重量％リン酸二水素アンモニウム水溶液であり、硼酸系化成液とは液温８５℃の３重量％硼酸アンモニウム水溶液である。印加電流密度は全ての化成液において１００ｍＡ／ｃｍ^２である。
【００１３】
【表１】

【００１５】
【実施例１〜３】
エッチング処理により実効表面積を拡大したアルミニウム箔を、アジピン酸系化成液にて７０Ｖまで化成を行い、０．２５重量％硝酸水溶液にて３分間減極処理を行った。次に化学処理として液温４０、５０、６０℃の温度の異なるイオン交換水に各々３分間浸漬処理し、４００℃の熱処理を行った後、リン酸系化成液にて９０Ｖまで修復化成を行った。このとき、皮膜生成処理の温度が４０℃未満の場合、皮膜の生成量が十分でないために皮膜処理による効果が得られ難い。また、６０℃を超える場合、生成した皮膜が厚くなり、化成電気量は低減できるが、箔特性が低下する。
【００１６】
【実施例４〜６】
エッチング処理により実効表面積を拡大したアルミニウム箔を、アジピン酸系化成液にて７０Ｖまで化成を行い、０．２５％重量硝酸水溶液にて３分間減極処理を行った。次に化学処理として液温４０、５０、６０の温度の異なるｐＨ１１のアルミン酸カリウム水溶液にて３分間浸漬処理し、４００℃の熱処理を行った後、リン酸系化成液にて９０Ｖまで修復化成を行った。また、アルミン酸カリウム水溶液のｐＨを９、１１、１２と変えたもの３種（５ａ、５ｂ、５ｃ）についても比較した。
なお、アルミン酸カリウム水溶液のｐＨが９未満または１２を超える場合、皮膜生成より箔の溶出が多くなり化成箔特性が維持できなくなる。また、皮膜生成処理の温度が、４０℃未満の場合皮膜の生成量が十分ではないために皮膜処理による効果が得られ難く、６０℃を超える場合生成した皮膜が厚くなり、化成電気量は低減できるが箔特性は低下する。
【００１８】
【実施例１０〜１２】
エッチング処理により実効表面積を拡大したアルミニウム箔を、アジピン酸系化成液にて７０Ｖまで化成を行い、０．２５重量％硝酸水溶液にて３分間減極処理を行った。次に化学処理として液温８０、９０、１００℃の温度の異なるｐＨ１１の珪酸カリウム水溶液に各々３分間浸漬処理し、４５０℃の熱処理を行った後、リン酸系化成液にて９０Ｖまで修復化成を行った。
また、珪酸カリウム水溶液のｐＨを１０，１１，１３と変えたもの３種（１１ａ、１１ｂ、１１ｃ）についても比較した。
なお、珪酸塩水溶液のｐＨが１０未満または１３を超える場合、皮膜生成より箔の溶出が多くなり化成箔特性が維持できなくなる。また、処理温度が８０℃未満の場合、化成電気量を低減させるのに十分な皮膜を得ることができない。
【００１９】
【従来例１】
エッチング処理により実効表面積を拡大したアルミニウム箔を、アジピン酸系化成液にて７０Ｖまで化成を行い、減極処理として０．２５重量％硝酸水溶液にて３分間浸漬処理し、４５０℃の熱処理を行った後、リン酸系化成液にて９０Ｖまで修復化成を行った。
【００２２】
上記実施例と従来例について、箔特性及び従来例に対する実施例の化成電気量比率を表３に示す。
【００２３】
【表３】

【００２４】
表３から明らかなように、本発明の化成方法によれば、減極処理後、化学処理を行うことにより化成電気量の低減を図り、かつ箔特性を向上させることができる。また、本発明は減極処理を複数回行う場合は、その任意の工程または全ての工程にて適用が可能である。
【００２５】
【発明の効果】
以上説明したように、本発明によれば減極処理後の化学処理により、修復化成時の化成電気量の低減を図ることができ、かつ箔特性の向上も図ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an electrode foil for an aluminum electrolytic capacitor.
[0002]
[Prior art]
A conventional aluminum electrolytic capacitor is formed by subjecting an aluminum foil whose effective surface area has been increased by etching treatment to a chemical conversion treatment and forming a anodic oxide film on the surface of the aluminum foil and a cathode foil via a separator. The capacitor element is wound and impregnated with a driving electrolyte, and is inserted into a case and sealed.
[0003]
The chemical conversion step of forming an anodic oxide film on the aluminum foil was performed according to the following procedure. That is, an aluminum foil having an effective surface area expanded by etching treatment is formed with a constant current in an aqueous solution of boric acid, phosphoric acid, adipic acid, citric acid, or a salt thereof, and after reaching a predetermined formation voltage, a constant voltage is reached. And hold for a certain period of time to complete the first stage formation. Depending on the operating voltage or application, a film forming step by chemical treatment may be performed before the first stage chemical conversion.
[0004]
Next, in order to remove defects and the like in the anodic oxide film generated in the first stage chemical conversion, a part of the generated anodic oxide film is subjected to depolarization treatment by dissolution treatment or heat treatment, and then repaired by anodic oxidation again. I do. This process may be repeated as necessary.
[0005]
[Problems to be solved by the invention]
However, in the above conventional chemical conversion process, the higher the chemical conversion voltage, the more defects in the anodized film in the first stage chemical conversion, and it is necessary to tighten the depolarization treatment conditions in order to maintain the chemical conversion foil characteristics. As a result, there is a problem that the amount of electricity in the restoration conversion increases.
[0006]
[Means for Solving the Problems]
The present invention has been found as a result of various investigations in view of the above-described conventional circumstances, and pays attention to the restoration formation process after the depolarization treatment among the steps of forming the anodized film, and the chemical treatment after the depolarization treatment. It is characterized by providing a chemical conversion foil having an excellent characteristic by reducing the amount of electricity by providing a film forming step.
[0007]
In the method for producing an anode foil for an aluminum electrolytic capacitor in which the surface is roughened and the effective surface area is increased to form an anodized film,
When the aluminum foil is formed at a formation withstand voltage of 160 V or less, after the depolarization treatment in the formation step, the following chemical treatment solutions (1) to (3):
(1) Pure water / ion-exchanged water having a liquid temperature of 40 to 60 ° C. ,
(2) Aluminate aqueous solution having a liquid temperature of 40 to 60 ° C. and a pH of 9 to 12,
(3) Silicate aqueous solution having a liquid temperature of 80 to 100 ° C. and pH of 10 to 13
A method for producing an electrode foil for an aluminum electrolytic capacitor, characterized in that a film is formed by chemical treatment according to, and an anodized film is formed after heat treatment.
[0008]
[Action]
By performing chemical treatment using the liquids (1) to (3) after the depolarization treatment, the formed films have the following actions (1) and (2), respectively.
[0009]
(1) Immersion treatment temperature: 40 to 60 ° C., chemical withstand voltage: 160 V or less
a) After the depolarization treatment, the hydrated film formed on the exposed defects becomes a pseudo boehmite film by chemical treatment with pure water or ion exchange water at 40-60 ° C. Therefore, the amount of chemical conversion electricity can be reduced, and a chemical conversion foil having excellent characteristics can be obtained.
b) After depolarization treatment, a pseudo boehmite film is formed by immersing in an aqueous aluminate solution having a pH of 9-12 at a treatment temperature of 40-60 ° C. and heat-treating the resulting hydrated film. Since the restoration and chemical conversion can be easily performed by using this, the amount of chemical conversion electricity can be reduced and a chemical conversion foil having excellent characteristics can be obtained.
[0010]
(2) Immersion treatment temperature: 80 to 100 ° C., chemical withstand voltage: 160 V or less,
After immersing in a silicate aqueous solution having a pH of 10 to 13 at a treatment temperature of 80 to 100 ° C., by performing a heat treatment, a protective coating is formed, and ions in the chemical conversion liquid enter the coating that is generated during the repair conversion. Therefore, the crystallization of the film is facilitated, the amount of chemical conversion electricity can be reduced, and a chemical conversion foil having excellent characteristics can be obtained.
[0012]
Examples of the present invention and conventional examples will be described based on the description in Table 1 below. The adipic acid-based chemical liquid is a 5 wt% ammonium adipate aqueous solution at a liquid temperature of 70 ° C, and the phosphoric acid-based chemical liquid is a 0.1 wt% ammonium dihydrogen phosphate aqueous solution at a liquid temperature of 85 ° C, The boric acid chemical conversion solution is a 3% by weight ammonium borate aqueous solution having a liquid temperature of 85 ° C. The applied current density is 100 mA / cm ² in all chemical conversion solutions.
[0013]
[Table 1]

[0015]
Examples 1 to 3
An aluminum foil whose effective surface area was enlarged by etching treatment was converted to 70 V with an adipic acid-based chemical conversion solution, and depolarized with a 0.25 wt% nitric acid aqueous solution for 3 minutes. Next, as chemical treatment, each is immersed for 3 minutes in ion-exchanged water having different liquid temperatures of 40, 50, and 60 ° C., heat-treated at 400 ° C., and then repaired to 90 V with a phosphoric acid-based chemical solution. It was. At this time, when the temperature of the film generation treatment is less than 40 ° C., the amount of film formation is not sufficient, and thus the effect of the film treatment is difficult to obtain. Moreover, when it exceeds 60 degreeC, the produced | generated film | membrane becomes thick and the amount of chemical conversion electricity can be reduced, but foil characteristics fall.
[0016]
Examples 4 to 6
An aluminum foil whose effective surface area was enlarged by etching treatment was converted to 70 V with an adipic acid-based chemical conversion solution, and depolarized with a 0.25% nitric acid aqueous solution for 3 minutes. Next, as chemical treatment, immersion treatment is performed for 3 minutes in a potassium aluminate aqueous solution of pH 11 having different liquid temperatures of 40, 50, and 60, heat treatment is performed at 400 ° C., and then restoration treatment is performed up to 90 V with a phosphoric acid-based chemical liquid. Went. Further, three types (5a, 5b, 5c) in which the pH of the aqueous potassium aluminate solution was changed to 9, 11, 12 were also compared.
In addition, when the pH of the potassium aluminate aqueous solution is less than 9 or exceeds 12, elution of the foil is greater than the formation of the film, and the chemical conversion foil characteristics cannot be maintained. In addition, when the temperature of the film generation treatment is less than 40 ° C., the amount of film formation is not sufficient, so the effect of the film treatment is difficult to be obtained. When the temperature exceeds 60 ° C., the generated film becomes thick and the amount of chemical electricity is reduced. Although it is possible, the foil properties are reduced.
[0018]
Examples 10-12
An aluminum foil whose effective surface area was enlarged by etching treatment was converted to 70 V with an adipic acid-based chemical conversion solution, and depolarized with a 0.25 wt% nitric acid aqueous solution for 3 minutes. Next, as chemical treatment, each was immersed for 3 minutes in potassium silicate aqueous solution of pH 11 with different liquid temperatures of 80, 90, and 100 ° C., subjected to heat treatment at 450 ° C., and then repaired to 90 V with a phosphoric acid-based chemical solution. Went.
Further, three types (11a, 11b, 11c) in which the pH of the aqueous potassium silicate solution was changed to 10, 11, 13 were also compared.
In addition, when pH of silicate aqueous solution is less than 10 or exceeds 13, elution of foil increases rather than film formation, and it becomes impossible to maintain chemical conversion foil characteristics. On the other hand, when the treatment temperature is less than 80 ° C., it is not possible to obtain a film sufficient to reduce the amount of chemical conversion electricity.
[0019]
[Conventional example 1]
An aluminum foil whose effective surface area is enlarged by etching treatment is converted to 70 V with an adipic acid-based chemical conversion solution, and as a depolarization treatment, it is immersed in a 0.25 wt% nitric acid aqueous solution for 3 minutes, and a heat treatment at 450 ° C. is performed. After that, restoration conversion was performed up to 90 V with a phosphoric acid-based chemical solution.
[0022]
Table 3 shows the foil characteristics and the chemical conversion ratio of the embodiment relative to the conventional example with respect to the above example and the conventional example.
[0023]
[Table 3]

[0024]
As is apparent from Table 3, according to the chemical conversion method of the present invention, the chemical treatment is performed after the depolarization treatment, thereby reducing the amount of chemical conversion electricity and improving the foil characteristics. Further, the present invention can be applied to any step or all steps when the depolarization treatment is performed a plurality of times.
[0025]
【The invention's effect】
As described above, according to the present invention, the chemical treatment after the depolarization treatment can reduce the amount of chemical electricity at the time of restoration and can improve the foil characteristics.

Claims

In the method for producing an anode foil for an aluminum electrolytic capacitor in which the surface is roughened and the effective surface area is increased to form an anodized film,
When the aluminum foil was formed at a formation withstand voltage of 160 V or less, a film was formed by chemical treatment with pure water / ion-exchanged water at a liquid temperature of 40 to 60 ° C. after the depolarization treatment in the formation step, followed by heat treatment. Then, the manufacturing method of the electrode foil for aluminum electrolytic capacitors characterized by forming an anodic oxide film.

In the method for producing an anode foil for an aluminum electrolytic capacitor in which the surface is roughened and an effective surface area is increased to form an anodized film,
When the aluminum foil is formed at a formation withstand voltage of 160 V or less, a film is formed by chemical treatment with an aqueous aluminate solution having a liquid temperature of 40 to 60 ° C. and a pH of 9 to 12 after the depolarization treatment in the formation step, and heat treatment is performed. A method for producing an electrode foil for an aluminum electrolytic capacitor, wherein an anodized film is formed after the step.

In the method for producing an anode foil for an aluminum electrolytic capacitor in which the surface is roughened and an effective surface area is increased to form an anodized film,
When the aluminum foil is formed at a formation withstand voltage of 160 V or less, a film is formed by a chemical treatment with a silicate aqueous solution having a liquid temperature of 80 to 100 ° C. and a pH of 10 to 13 after the depolarization treatment in the formation step, and heat treatment is performed. And then forming an anodized film, and a method for producing an electrode foil for an aluminum electrolytic capacitor.