JP2644311B2 - Manufacturing method of aluminum foil for electrolytic capacitor electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to aluminum foil,
The present invention relates to a method for producing an aluminum foil material for an electrolytic capacitor electrode which is roughened by chemical etching.

[Problems to be solved by conventional technology and invention]

The aluminum foil used for the electrolytic capacitor electrode is subjected to electrochemical or chemical etching in an acid or alkaline bath to roughen the surface and increase the surface area in order to increase the capacitance and improve the performance. Is being increased. However, the roughened state depends on the degree of etching, but if the etching is small, the surface is not sufficiently roughened. If the etching is excessive, the amount of corrosion becomes excessive, and the capacitance is reduced and the strength is reduced. Therefore, it is necessary to control the etching to an appropriate amount. However, even if the etching is controlled, the entire foil is not uniformly etched, resulting in unevenness and a portion where characteristics are deteriorated.

[Means for solving the problem]

The present invention has been made in view of the above and, as a result of various studies, has developed a method for manufacturing an aluminum foil material for an electrolytic capacitor electrode that solves the above-mentioned problems.

That is, in the production method of the present invention, a pure Al ingot having a purity of 99.9 wt% or more is hot-rolled, and then, when cold rolling is performed, an alkaline solution having a pH of 10 or more before the cold rolling reduction exceeds 96%. 1 to
It is characterized by performing alkali cleaning for 100 seconds.

[Action]

In the present invention, pure Al having a purity of 99.9 wt% or more is used because Fe inevitably contained in Al actively acts on the self-solubility of the foil, but when the purity of Al is less than 99.9 wt%, etching is performed. This is because the reaction with the solution becomes extremely violent and the etching cannot be performed normally. Therefore, the purity of Al used in the present invention is
The content may be 99.9 wt% or more, and as long as the content is satisfied, an element such as Cu, Si, Mn, Mg, or Ti may be contained as an active ingredient.

The present invention specifies a method for producing an aluminum foil material for an electrolytic capacitor electrode having the above composition. First, an ingot having a thickness of 200 to 700 mm is produced by DC casting or electromagnetic casting. The homogenization treatment may be performed also as the heating of the hot rolling, or the heating of the hot rolling may be performed again after performing the homogenization treatment. Usually, the temperature is 380 ° C to 620 ° C for about 0.5 to 24 hours. In the case of DC casting, facing is performed before hot rolling is performed. The conditions of the hot rolling are as usual, and the thickness of the hot-rolled plate is 1 to 10 mm. That is, ingot production, homogenization treatment,
The hot rolling step is not particularly limited, and may be performed as usual.

The main object of the present invention is to carry out alkali washing with an alkaline solution having a pH of 10 or more for 1 to 100 seconds before the cold rolling ratio exceeds 96% when performing cold rolling after hot rolling.

Where the cold rolling rate is Expressed by

Here, the cold rolling may be performed in several passes, or annealing may be performed during the cold rolling. Annealing does not affect the present invention whether it is a batch type or a continuous annealing type.

Next, the reason why the cleaning treatment is performed with an alkali solution is to prevent the Fe of about 0.5 to 10 μm adhering to the surface of the foil ground on the hot-rolled ground during the production of the foil ground from causing uneven etching. Thus, the cold rolling rate when performing etching is 96
% Or more, the Fe powder adhering to the surface during hot rolling is too deeply buried, cannot be completely removed by alkali cleaning, and etching unevenness cannot be sufficiently prevented.

The alkaline washing conditions are 1 to 10 with an alkaline solution having a pH of 10 or more.
Process for 100 seconds. By this treatment, the aluminum surface is etched at a maximum of about 5 μm. However, if the concentration of the alkaline solution is less than pH 10 or the washing time is less than 1 second, the washing becomes insufficient, preventing the occurrence of etching unevenness becomes insufficient, and the washing time exceeding 100 seconds is from the viewpoint of productivity. Not only is it undesirable, but Al is excessively dissolved by washing, and even pure Al with a purity of 99.9 wt% or more is contained
-An Fe-based crystallization phase remains on the surface, which acts in the same manner as Fe powder, causing etching unevenness.

In the present invention, the temperature for performing the alkali washing in the range of 15 to 90 ° C. is sufficient, and the alkali used is NaOH, KOH,
(OH) ₂ or the like may be used, but it is particularly desirable to use 0.3 to 10% NaOH and to perform the treatment for 5 to 60 seconds.

Further, in the present invention, it is desirable to perform acid cleaning after alkali cleaning. Acid cleaning is an action of preventing alkali solution from remaining on the plate surface and deteriorating surface properties by neutralizing alkali with acid, and dissolving a crystallized phase floating on the surface by alkali cleaning, resulting in uneven etching. To prevent

 Hereinafter, the present invention will be described in detail with reference to examples.

Example While the ingot of pure Al shown in Table 1 was hot-rolled to a thickness of 3 mm and 6.5 mm under ordinary conditions, and then cold-rolled to a thickness of 0.1 mm, the conditions shown in Table 2 were applied. In the course of cold rolling, alkali washing with NaOH was performed. The Al foil thus obtained was annealed at 500 ° C. for 2 hours, and the obtained Al foil was electrolytically etched under ordinary conditions (etching solution: 5 wt% hydrochloric acid aqueous solution, temperature: 75 ° C., DC current density: 10A / dm ^2, the etching time: 7
Min) to examine the occurrence of uneven etching. The results are compared with the conventional Al foil fabric without alkali cleaning,
Also shown in the table.

As is clear from Tables 1 and 2, the method of the present invention No.
No unevenness in etching was observed in any of the Al foil fabrics manufactured in accordance with 1, 2, 5, and 6.

On the other hand, unevenness of etching was observed in the Al foil fabrics manufactured by the conventional methods Nos. 8 and 9 without alkali cleaning and the comparative methods Nos. 3, 4 and 7 deviated from the method of the present invention.

〔The invention's effect〕

As described above, according to the present invention, an aluminum foil material for an electrolytic capacitor electrode having excellent etching characteristics can be manufactured, and the characteristics and quality of the electrolytic capacitor can be improved, and industrially remarkable effects are exhibited. .

Claims (1)

(57) [Claims] 1. A pure Al ingot having a purity of 99.9% by weight or more is hot-rolled, and then cold-rolled. A method for producing an aluminum foil fabric for an electrode of an electrolytic capacitor, which comprises performing an alkali cleaning for 100 seconds.