JPH09320904A - Driving electrolyte for electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase of tanδ and decrease of capacitance, by using ethylene glycol as main solvent, dissolving organic acid or its salt, and compounding a specific amount of propargyl alcohol. SOLUTION: The following is used as the electrolyte of an aluminum electrolytic capacitor, ethylene glycol is used as the main solvent, organic acid or its salt is dissolved, and propargyl alcohol of 0.5-5wt.% is compounded. Propargyl alcohol has triple bond in a particle and tightly couples to an anode oxide film of the aluminum electrolytic capacitor, so that a stable adsorption film which is not dissolved in electrolyte is formed. The adsorption film is formed on the whole part of the oxide film surface, faster than that organic acid or its salt is adsorbed on the surface of the anode oxide film. Thereby organic acid or its salt in the electrolyte can be prevented from being adsorbed by a film, complex from being formed, and the organic acid or its salt from being dissolved in the electrolyte.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrolytic solution for driving an electrolytic capacitor.

[0002]

2. Description of the Related Art Conventionally, an electrolytic solution for driving an aluminum electrolytic capacitor for medium and high voltage (hereinafter, simply referred to as an electrolytic solution).
For this, an electrolytic solution in which an organic acid or a salt thereof is dissolved in a solvent mainly composed of ethylene glycol is used. These electrolytes are required to have a high-voltage conversion capacity for aluminum, and therefore various organic acid species have been investigated.

[0003]

An electrolytic solution containing an organic acid or a salt thereof, which has been found to have a high-voltage conversion ability, has been used to realize an electrolytic capacitor which can be used in a high voltage range. However, these aluminum electrolytic capacitors also have the drawback of causing a decrease in reliability such as a decrease in capacitance and an increase in tan δ in a long-term reliability test at high temperature.

[0004]

As a result of various studies on the above-mentioned problems, the present inventor has found that the main cause is that an organic acid or a salt thereof in an electrolytic solution undergoes a complex-forming reaction on the electrode surface to form a complex-forming product. It has been found that the addition of propargyl alcohol to the electrolytic solution is effective for preventing the complex formation reaction.

That is, using ethylene glycol as the main solvent,
An electrolytic solution for an electrolytic capacitor, which comprises dissolving an organic acid or a salt thereof, and adding 0.5 to 5% by weight of propargyl alcohol.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The above-mentioned organic acid or salt thereof having a high-voltage conversion ability is adsorbed on the surface of an anodized film of an electrolytic capacitor when left at high temperature for a long period of time to cause a complex formation reaction, and its reaction product Elutes in the electrolyte.

When the complex-forming product begins to dissolve, the characteristics of the anode foil are remarkably deteriorated and the long-term high temperature reliability of the aluminum electrolytic capacitor is deteriorated.

In particular, under a high temperature load, the anodized film in the electrolytic capacitor is largely dissolved, which causes an increase in tan δ. On the other hand, when no load is applied, the amount of the complex-forming reactant adsorbed becomes large, which increases the leakage current.

Propargyl alcohol has a triple bond in the molecule and strongly binds to the anodic oxide film of the aluminum electrolytic capacitor to form a stable adsorption film that is not dissolved in the electrolytic solution. This adsorption film is formed over the entire surface of the oxide film faster than the organic acid or its salt adsorbs on the surface of the anodic oxide film, so that the adsorption of the organic acid or its salt in the electrolytic solution on the film, Complex formation and further elution into the electrolytic solution can be prevented, and a stable anodized film can be obtained for a long period of time.

[0010]

EXAMPLES Specific examples of the present invention will be described below. The electrolytic solutions according to the present invention (sample symbols A-1 to A-3, B-1 to B-3, C-1 to C- as examples are shown in Tables 1 to 4).
3, D-1 to D-3) and compositions of conventional electrolytic solutions (sample symbols A-0, B-0, C-0, D-0) for comparison,
The specific resistance at 30 ° C. and the withstand voltage at 85 ° C. are shown.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

As is clear from Tables 1 to 4, sample symbols A-1 to A-3, B-1 to B-3, C-1 according to the present invention.
To C-3 and D-1 to D-3 have the same specific resistance and withstand voltage as conventional electrolytic solutions (sample symbols A-0, B-0, C-0, D-0). .

Using the above electrolytic solution, a rating of 450 V-330
Made an aluminum electrolytic capacitor of μF, 105 ℃
The results of the rated voltage application test and the no-load test are shown in Table 5 and Table 6, respectively. 400 in the applied test
It is a characteristic value at 0 hours and at 2000 hours in a high temperature no-load test.

[0017]

[Table 5]

[0018]

[Table 6]

As is clear from Table 5, sample symbols A-1 to A-3, B-1 to B-3, C-1 to C- according to the present invention.
The electrolytic capacitors using the electrolytic solutions of Nos. 3, D-1 to D-3 are the conventional electrolytic solutions (sample symbols A-0, B-0, C-0, D-0) in the 105 ° C rated voltage application test. The increase in tan δ is significantly suppressed, and the change in capacitance and the change in leakage current are also improved. Also, as is clear from Table 6 in the 105 ° C. no-load test, the increase in the leakage current in the example is smaller than that in the conventional example,
The change in capacitance and the change in tan δ are small and stable. Here, the blending amount of propargyl alcohol is 0.
Effective when combined with 5 to 5% by weight, 0.5% by weight
If it is less than 5% by weight, there is no effect, and if it exceeds 5% by weight, the high-voltage conversion ability of the electrolytic solution decreases.

[0020]

INDUSTRIAL APPLICABILITY As described above, the electrolytic solution of the aluminum electrolytic capacitor according to the present invention can provide a highly reliable aluminum electrolytic capacitor at high temperature as compared with the conventional electrolytic solution, and can be industrially and practically used. Is of great value.

Claims (1)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor, which comprises ethylene glycol as a main solvent, an organic acid or a salt thereof dissolved therein, and 0.5 to 5% by weight of propargyl alcohol.