JPH0969471A - Capacitor electrolyte for electrolytic solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrolytic solution which can be kept high in long-term properties of absorbing hydrogen gas generated in an electrolytic capacitor case by a method wherein a specific % by weight of 3-nitropyrimidine is dissolved into the electrolytic solution. SOLUTION: Ethylene glycol is used as polyvalent alcohol solvent. Ammonium boride, ammonium butyl octanodiate, ammonium sebacate, ammonium suberate, ammonium azelate, ammonium benzonate or ammonium adipdiate is used as solute. 0.01 to 2.0% by weight of 3-nitropyrimidine is dissolved into the solution composed of these solvent and solute. Hydrogen gas generated in an electrolytic capacitor is reduced to 13 to 30% of that generated in a conventional one, so that the capacitor can be prolonged in service life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for electrolytic capacitors.

[0002]

2. Description of the Related Art As the performance of communication equipment and measuring equipment has improved, it has become necessary to further improve the electrical characteristics and life of electrolytic capacitors incorporated in such equipment.
This electrolytic capacitor is for medium and high voltage, and for example, has a structure in which a capacitor element impregnated with an electrolytic solution is housed in an aluminum case or the like, and a lid is attached and sealed. The electrolytic solution has a composition in which a polyhydric alcohol such as ethylene glycol is used as a main solvent and an ammonium salt of carboxylic acid is dissolved as a main solute.

By the way, this electrolytic solution reacts with the electrode foil to generate hydrogen gas. And when hydrogen gas is generated,
The pressure inside the case rises. When this internal pressure reaches a predetermined value, the explosion-proof valve provided on the lid or the like operates. As a result, the electrolytic capacitor becomes defective. Conventionally, an aromatic nitro compound is dissolved in an electrolytic solution for the purpose of suppressing the generation of hydrogen gas, delaying the operation of the above explosion-proof valve, and improving the life of the electrolytic capacitor.

[0004]

However, the electrolytic solution in which the aromatic nitro compound is dissolved has a drawback that the spark generation voltage is likely to be lowered when the dissolved amount is large. Therefore, although the amount of the aromatic nitro compound dissolved is usually reduced, it has a drawback that the action of absorbing hydrogen gas cannot be continued for a long time and the effect of improving the life of the electrolytic capacitor is low.

An object of the present invention is to provide an electrolytic solution for an electrolytic capacitor, which is capable of absorbing the generated hydrogen gas for a long period of time and improving the life of the electrolytic capacitor by improving the above drawbacks.

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention uses 0.01 to 2.0 wt% of 3-nitropyrimidine in an electrolytic solution for electrolytic capacitors containing polyhydric alcohols as a main solvent. % Electrolytic solution for electrolytic capacitors.

Polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, 1,4
-Use butanediol or the like.

The amount of 3-nitropyrimidine dissolved is
If it is less than 0.01 wt%, the effect of suppressing the generation of hydrogen gas is low, and if it is more than 2.0 wt%, the spark generation voltage is lowered and the withstand voltage of the electrolytic capacitor is lowered. Therefore, 3
The amount of nitropyrimidine dissolved is preferably in the range of 0.01 to 2.0 wt%.

[0009]

The 3-nitropyrimidine in the electrolytic solution absorbs hydrogen gas, which is the majority of the gas generated in the case of the electrolytic capacitor. Therefore, it is possible to prevent the internal pressure of the electrolytic capacitor from rising.

[0010]

EXAMPLES The present invention will be described below based on examples.
Ethylene glycol is used as the polyhydric alcohol, and this is used as the solvent. As the solute, ammonium borate, ammonium butyloctanedioate, ammonium sebacate, ammonium suberate, ammonium azelate, ammonium benzoate, and diammonium adipate are used. Then, 3-nitropyrimidine having the structural formula of Chemical formula 1 is dissolved in a solution containing these solvents and solutes.

[0011]

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Next, examples of the compositions shown in Tables 1 and 2,
With respect to the electrolytic solutions of the conventional example and the comparative example, the specific resistance at a temperature of 30 ° C. and the spark generation voltage at a temperature of 85 ° C. were measured.

[0013]

[Table 1]

[0014]

[Table 2]

Incidentally, m-dissolved in Conventional Example 1 to Conventional Example 4
The structural formulas of nitrobenzoic acid, P-nitrotoluene, and O-nitrophenol are as shown in [Chemical formula 2] to [Chemical formula 4].

[0016]

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[0017]

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[0018]

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As is apparent from Table 1, in Examples 1 to 10, the specific resistance was 350 to 1000 Ω · cm and the spark generation voltage was 350 to 440V. Further, in Conventional Example 1 to Conventional Example 4, the specific resistance is 350 to 1000 Ω · cm and the spark generation voltage is 340 to 430V. That is, in Examples 1 to 10, the specific resistance was the same as in Conventional Example 1 to Conventional Example 4, but the spark generation voltage was higher. In addition, 3-
Comparative Example 2 in which the amount of nitropyrimidine dissolved was 5.0 wt%
Has a spark generation voltage of 280 V, and the example 1 to example 1
The size is 4/5 or less compared to 0.

Further, the amount of gas generated in the case was measured for aluminum electrolytic capacitors having a rating of 400 V, 330 μF and a case size of φ30 × 45, which were impregnated with the electrolytic solutions having the compositions shown in Tables 1 and 2. The measurement method is from Example 1
For Example 4, Conventional Example 1 and Comparative Examples 1 and 2, the temperature was 85 ° C. and other Examples 5 to 10 were used.
For Conventional Example 2 to Conventional Example 4, a rated voltage of 400 V was applied to each atmosphere at a temperature of 105 ° C. for 2000 hours.
The amount of gas generated after standing is measured. The number of samples shall be 10 each. The measured amount is an average value.

As is clear from Tables 1 and 2, the amount of gas generated was 1.3 to 1.5 ml for the electrolytic capacitors impregnated with Examples 1 to 10 and the electrolytic amount impregnated with Conventional Examples 1 to 4 was used. The capacitor is 5.0-10.0 ml and the electrolytic capacitor impregnated with Comparative Example 1-Comparative Example 2 is 1.4-18.0 ml.
Becomes That is, Examples 1 to 10 are conventional examples 1 to
The amount of gas generation is 13 to 30% as compared with Conventional Example 4. Comparative Example 1 is an electrolytic solution in which the amount of 3-nitropyrimidine dissolved is 0.005 wt%, but the amount of gas generated by an electrolytic capacitor using this electrolytic solution is 18.0 ml. It is 12 times that of 10.

[0022]

As described above, according to the present invention, since 3-nitropyrimidine is dissolved in 0.01 to 2.0 wt%, the generated hydrogen gas can be absorbed for a long time and the life of the electrolytic capacitor is improved. An electrolytic solution for an electrolytic capacitor can be obtained.

Claims (1)

[Claims] 1. An electrolytic solution for an electrolytic capacitor, wherein 0.01 to 2.0 wt% of 3-nitropyrimidine is dissolved in the electrolytic solution containing a polyhydric alcohol as a main solvent.