JPS60726A - Method of producing anode foil for aluminum electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high-voltage anode foil for an At electrolytic capacitor, particularly the CV product (the product of the capacitance per unit area of the anode foil and the withstand voltage value of the foil). The present invention relates to a manufacturing method for improving.

In general, anode foil for At electrolytic capacitors is made by first etching the A4 foil to roughen the surface and expand the surface area, and then forming an oxide film Az on the etched foil.
It is manufactured through a chemical conversion process that forms 2o3.

This chemical conversion process is roughly divided into a pretreatment process 1 and an oxide film formation process 2 as shown in FIG. Usually, after boiling in pure water to form a film of aluminum hydroxide AL(OH)3 on the surface of the etching foil, in the next oxide film forming step, the foil is heated to a chemical formation voltage in an electrolytic solution called chemical liquid. is applied to perform electrolytic oxidation to convert the AL(OH)s into Az2o3, thereby manufacturing the anode foil 4. By the way, the larger the CV product of the anode foil manufactured in this way, the more compact the A4 electrolytic capacitor using the anode foil can be.
Eleven studies have been conducted on increasing the V product.

There are two methods to increase the CV product. The first method is to increase the etching magnification of the etching foil, that is, to increase the degree of roughening of the surface of the At foil, or in other words, to increase the expansion rate of the surface area. The second method is to form a uniform and uneven film of A42o3 on the etching foil by chemical conversion.
In order to form a film efficiently, it is important to form as much At(OH)3 as possible in the pretreatment process, but it is important to increase the boiling time of the etched foil in pure water. However, it is known that the weight of the foil does not increase and At(OH)3 is not formed beyond a certain limit. Therefore, the foil is anodized at a certain anodizing voltage to form an oxide film XZ, O3. There is a limit to the increase in the CV product of the anode foil after formation. Figure 6 shows the pure water foil treatment when the CVi of the anode foil after chemical conversion without boiling in pure water is 100. This shows the relationship between time and CV product.
Even if the boiling time is increased, the CV product remains constant and shows a tendency to saturate. Therefore, conventional foiling time is generally about 10 minutes.

An object of the present invention is to provide a method for manufacturing a high-pressure anode foil, which improves the pretreatment step of the chemical conversion step and increases and improves the CV product of the anode foil after forming an oxide film compared to anode foils produced by conventional methods. do. The present invention will be explained in detail below.

FIG. 2 is a process diagram of the manufacturing method of the present invention, where 11 and 12 are pretreatment steps, 11 is a conventional pure water boiling step, and 12 is a boiling step using an organic acid aqueous solution, which is a feature of the present invention. (hereinafter referred to as organic acid boiling process).

That is, the present invention adds an organic acid boiling process to the pretreatment process of the conventional chemical conversion process in addition to the pure water boiling process.

The present invention will be described below based on examples. After boiling the At etching foil in pure water for 10 minutes as a pretreatment, a benzoic acid aqueous solution with a concentration of Q and 5 wt% was prepared as an organic acid aqueous solution, and the foil was further boiled in the aqueous solution for 2 to 10 minutes. The foil after boiling with organic acid is chemically converted in an oxide film forming process, and the CV product of the completed anode foil is measured in this process. When compared with the CV product of the foil, it was found that the CV product of the anode foil treated with organic acid boiling of the present invention increases by about 10%. The result of this increase in CV product is shown in FIG. From this, it can be seen that 5 minutes is sufficient for the organic acid boil treatment time. Next, the same treatment as above was performed using an aqueous solution of phenic acid or the like as another organic acid, and the CV products were compared, and it was confirmed that each had an increasing effect. The effects of these organic acid treatments are thought to contribute to promoting the formation of the oxide film (At203) and increasing its uniformity.
Although the mechanism has not yet been fully elucidated, it is thought that the surface activation effect of the etching foil surface has a favorable effect on the formation of At2°3. Also, considering the concentration of organic acid aqueous solution, 4. Regarding benzoic acid and citric acid,
The etched foils were boiled in pure water for 10 minutes using aqueous solutions of various concentrations, then treated with an organic acid foil for 5 minutes each, and the product of the anode foil obtained by chemically converting the etched foils was calculated as follows: Assuming that the CV product when only water boiling treatment is performed is 100,
This is shown in FIG. The degree of increase in the CV product is small when the concentration is low, and increases when the concentration is high, but it tends to decrease again when the concentration exceeds a certain level. A range of concentrations is suitable for the purposes of this invention.

As described above, by adding an organic acid boiling treatment in addition to the conventional pure water boiling treatment as a pretreatment means, it is possible to increase and improve the CV product of the obtained anode foil. It is possible to provide an excellent anode foil for At electrolytic capacitors that cannot be obtained by conventional manufacturing methods.

The amount of anode foil used in the electrolytic capacitor can be reduced by the increase in the CV product compared to the conventional method, and the capacitor can be made smaller in size, which is useful both economically and practically.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing a conventional manufacturing method. FIG. 2 is a process diagram showing the manufacturing method of the present invention. FIG. 6 is a characteristic diagram of the anode foil produced by the conventional manufacturing method. 4 and 5 are characteristic diagrams of an anode foil according to an embodiment of the present invention. 1: Pretreatment step, 2: Oxide film formation step, 6: Enoting foil 4: Anode foil, 11: Pure water boiling step. 12: Organic acid boil treatment process patent applicant Fig. 61 Sumire 2 Fig. Y 3 Fig. ¥14 Fig.

Claims (2)

[Claims] (1) A method for manufacturing an anode foil for an aluminum electrolytic capacitor, characterized in that in the process of chemically converting the alumino etched foil to produce the anode foil for an aluminum electrolytic capacitor, a pre-acid boiling treatment is performed. (2) The organic acid is either benzoic acid or citric acid,
The method for manufacturing an anode foil for an aluminum electrolytic capacitor according to claim 1, wherein the aqueous solution concentration is 0.01 to 1.0 wt%.