JPS60176218A - Electrolyte 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 Field of Industrial Application The present invention relates to an electrolyte for an aluminum electrolytic capacitor.

Conventional Structure and Problems Conventionally, electrolytes for this type of aluminum electrolytic capacitors, especially for medium and high voltages, have been prepared using ethylene glycol with boric acid or ammonium borate dissolved as an electrolyte because the spark generation voltage can be relatively high. liquid was used.

However, in such an electrolytic solution, a large amount of water is generated in the electrolytic acid due to the crystallization water directly released from the boric acid and the condensed water generated by the esterification reaction between ethylene glycol and boric acid. When used in an aluminum electrolytic capacitor with a capacity exceeding 100 mL, water in the electrolyte becomes water vapor and evaporates, raising the internal pressure inside the bag 7 of the aluminum electrolytic capacitor, leading to its destruction. In order to solve these problems, loaded carboxylic acids such as adipic acid or benzoic acid or salts of carbon dioxide, which have a very slow esterification reaction with ethylene glycol, were investigated as electrolytes.However, these Since the esterification reaction in electrolytes using organic acids or their salts is very slow, the amount of water produced in the electrolyte is also very small.
Although it is possible to suppress the pressure increase inside the AltJ capacitor package at high temperatures, these organic acids and their salts alone have the disadvantage that the required high spark generation voltage cannot be obtained.

OBJECT OF THE INVENTION The present invention eliminates these conventional drawbacks, and aims to provide an aluminum electrolytic capacitor that suppresses the increase in internal pressure of aluminum electrolytic capacitors at high temperatures and sufficiently increases spark generation voltage without increasing resistivity. The purpose is to provide an electrolytic solution for medium and high voltages in electrolytic capacitors.

Structure of the Invention In order to achieve this object, the present invention uses ethylene glyco-JVk as a main solvent consisting of any one of an organic acid, an organic acid salt, an inorganic acid, and an inorganic acid salt, or a mixture thereof. It is composed of a solution in which 0.1 to 30 wt % of polyoxyethylene dicarboxylic acid is dissolved in a solution in which a solute is dissolved.

Polyoxyethylene dicarboxylic acid is a polymerized compound with the chemical formula shown below.

The electrolytic solution composed of HooCCH, (QC2H4)nOCH2COOH has a very small internal water content, so there is almost no increase in the internal pressure of the aluminum electrolytic capacitor at high temperatures, and the added polyoxy Due to the effect of ethylene dicarboxylic acid, the spark generation voltage can be increased without increasing the specific resistance of the electrolyte.

Description of examples Examples according to the present invention will be described below.

First, the composition of the electrolytic solution in the example of the present invention will be specifically illustrated. Table 1 shows a comparison with conventional composition examples. A comparison of the chemical formation and discharge characteristics of the examples selected from Table 1 and the conventional example due to constant current chemical formation is shown in the figure. In addition, electrolytic capacitors based on each composition in Table 1 (
Tables 2 and 3 show the results of a 1000-hour load test conducted at 105° C. for 400 V, 220 μF).

Table 2 shows the short circuit occurrence rate during the load test, Table 3 shows the capacitance change rate during the load test, and the tangent of the 41 loss angle (tal).
Iδ) and leakage current characteristics.

From Table 1, Table 2, Table 1 and the figures, the electrolytic solution of the present invention has a spark starting voltage of 7.5% without significantly decreasing the resistivity compared to conventional electrolytic solutions.
It can be seen that the voltage can be increased as high as 0 to 80V.

Example 1 of the present invention from Table W2 and Table 3. The electrolyte of Example 2 was the same as that of Conventional Example 2. Compared to the electrolytic solution of Conventional Example 3, as a result of a high temperature load test at 106°C, the occurrence rate was 1 to 1.

It can be seen that all the characteristics of the capacitance change rate, tan δ change rate, and appearance change are excellent.

The above-mentioned effects of adding polyoxyethylene dicarboxylic acid are similar to other consonant carboxylic acids such as formic acid, acetic acid, succinic acid, glutaric acid, and azelaic acid, and /I-saturated carboxylic acids such as maleic acid and fumaric acid. The same thing can be seen in organic acids such as boric acid, etc. (ζ organic acids).

By the way, the effect of polyoxyethylene dicarboxylic acid on increasing the spark starting voltage is highly dependent on the average molecular weight.

If the uniform molecule L1 (\1) is less than 200, the spark 1311 starting voltage and Ge1 effect will be very low, making it impractical.

When the average molecular weight exceeds 20,000, polyoxyethylene dicarboxylic acid has poor compatibility with the electrolyte, crystallizes in the electrolyte, and has no negative effect on the properties of the electrolyte. .

Therefore, polyoxyethylene dicarboxylic acid has an average molecular weight between 200 and 20,000, and has a high spark starting voltage.
Considering crystallization, the addition to the pyr solution is 0.1 to 3.
It is preferable to do this within a range of 0 wt%.

Effects of the Invention As shown in (a) above, the inventive feature is an electric i! for medium and high voltage aluminum electrolytic condensers that improves the spark starting frost 4 pressure without lowering the resistivity. By using one cup of the electrolytic solution of the present invention, it is possible to provide an extremely reliable medium-high voltage aluminum electrolytic capacitor.

[Brief explanation of drawings]

The figure is a graph showing the ratio of chemical formation/discharge characteristics of the Ichi 11N' liquid of the additive example of the present invention and the pancreatic juice of the conventional example during constant current chemical formation.

Claims (2)

[Claims] (1) Add 0.1% polyoxydiethylene dicarboxylic acid to a solution of the substrate dissolved in a solvent mainly composed of ethylene glycol.
An electrolytic solution for aluminum electrolytic capacitors, characterized in that it is dissolved in wt% to 30wt%. (2) Consists of any one of organic acids, organic acid salts, inorganic acids, and inorganic acid salts, or a mixture thereof.3) Average molecule of polyoxydiethylene dicarboxylic acid.