JPH09232188A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the tanδ characteristic and the leakage current characteristic of an electrolytic capacitor by containing trehalose. SOLUTION: In an electrolyte for electrolytic capacitor that polyhydric alcohols are used as a main solvent and at least a species of an organic acid, an organic acid salt, a boric acid or a borate is dissolved, it contains trehalose. As the polyhydric alcohols, ethylene glycol, diethylene glycol, propylene glycol, glycerol or the like is used. Further, as the organic acid, an adipic acid, a sebacic acid, an azelaic acid, a caprylic acid, a benzoic acid or the like a used. As the organic acid salt, salts of these organic acids are used. The trehalose are added to a solution in which an organic acid, an organic acid salt, a boric acid or a borate is dissolved in the polyhydric alcohols. Thereby, it is possible to hold effects of reconditioning an anode oxide film for a long period, and to obtain an electrolyte capable of improving life of the electrolytic capacitor.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an electrolytic solution for an electrolytic capacitor.

[0002]

2. Description of the Related Art An electrolytic capacitor such as an aluminum electrolytic capacitor has a structure in which a capacitor element formed by winding an electrode foil together with a separator is impregnated with an electrolytic solution. This electrolytic solution has a composition in which boric acid, an organic dibasic acid or a salt thereof is dissolved in a solvent mainly composed of a polyhydric alcohol such as ethylene glycol.

By the way, the anodic oxide film formed on the electrode foil is damaged during the manufacturing process and use of the electrolytic capacitor.
The electrolyte generally repairs this damaged anodic oxide coating. In particular, sugar alcohols such as mannitol and sorbit have been conventionally added to the electrolytic solution for the purpose of enhancing the effect of repairing the damaged anodic oxide film and improving the pressure resistance.

[0004]

However, an electrolytic solution containing a sugar alcohol such as mannitol has a drawback that it cannot maintain the effect of repairing an anodized film for a long period of time. Therefore, the electrolytic capacitor impregnated with this electrolytic solution tends to increase tan δ and leakage current and has a short life.

An object of the present invention is to provide an electrolytic solution for an electrolytic capacitor, which is capable of improving the above drawbacks, maintaining the effect of repairing an anodized film for a long period of time, and improving the life of the electrolytic capacitor.

[0006]

Means for Solving the Problems The present invention uses a polyhydric alcohol as a main solvent, and in an electrolytic solution for an electrolytic capacitor in which at least one kind of organic acid, organic acid salt, boric acid or borate is dissolved, An electrolytic solution for an electrolytic capacitor, which contains trehalose.

Since trehalose is contained in the electrolytic solution, the effect of repairing the anodic oxide film on the electrode foil can be maintained for a long period of time. Therefore, increase in tan δ and leakage current of the electrolytic capacitor can be suppressed, and the life can be improved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the polyhydric alcohols, ethylene glycol, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol and the like are used. As the organic acid, adipic acid, sebacic acid, azelaic acid, caprylic acid, benzoic acid, 1,6-decanedicarboxylic acid, 1,10-decanedicarboxylic acid, 5,6-decanedicarboxylic acid or the like is used. As the organic acid salt, salts of these organic acids are used. Then, trehalose is added to a solution prepared by dissolving an organic acid, an organic acid salt, boric acid, or a borate in the above polyhydric alcohol. This trehalose may be produced by any method and may be derived from, for example, JP-A-7-2.
As described in 13283, those derived from starch by the enzymatic saccharification method are used. There is Trehaose (trade name of Hayashibara Shoji Co., Ltd.) as a commercial product of Trehalose. The amount of trehalose added is 0.5 to 3
The range of 0 wt% is preferable, and if it is less than 0.5 wt%, the effect of repairing the anodized film is lowered, and if it is more than 30 wt%, the specific resistance of the electrolytic solution increases. In addition, mannitol, sorbit, phosphoric acid or the like may be dissolved as an additive.

[0009]

Embodiments of the present invention will be described below. The solvent is
Polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin are used. In this solvent, as a solute ammonium adipate, ammonium sebacate,
Each organic acid salt of ammonium 1,6-decanedicarboxylate and ammonium borate are dissolved. Then, trehalose and phosphoric acid are dissolved as additives.

Next, a high temperature load test was carried out on the examples comprising the components shown in Table 1 and conventional aluminum electrolytic capacitors impregnated with an electrolytic solution.

[0011]

[Table 1]

The aluminum electrolytic capacitors impregnated with the electrolytic solution of Example 1 and Conventional Example 1 were rated at 200 WV, 56.
0 μF. The rating of the aluminum electrolytic capacitor impregnated with other electrolytic solution is 400 WV and 150 μF. The test temperature was 90 ° C. for the aluminum electrolytic capacitors impregnated with the electrolytic solutions of Examples 6 to 8 and Conventional Example 4.
The material impregnated with other electrolytic solution has a temperature of 110 ° C. Furthermore, the test time is 5000 hours. The number of samples is 20 each. The measurement results are shown in Table 2.

[0013]

[Table 2]

As is clear from Table 2, after being left to stand for 2000 hours, NO impregnated with the electrolytic solutions of Examples 1 to 8 was used.
1 to NO8 aluminum electrolytic capacitors have a tan δ of 0.04
0 to 0.089 and the leakage current is 17 to 40 μA. On the other hand, in the aluminum electrolytic capacitors of NO9 to NO13 impregnated with the electrolytic solutions of Conventional Example 1 to Conventional Example 5, tan δ is 0.060 to 0.155 and leakage current is 100 to 40.
0 μA. Therefore, the aluminum electrolytic capacitors using the electrolytic solutions of Examples 1 to 8 are smaller in tan δ and leakage current than those using the electrolytic solutions of Conventional Example 1 to Conventional Example 5, and deterioration is suppressed. ing.

In particular, the solvent and the main solute are the same component,
When comparing the aluminum electrolytic capacitors using the electrolytic solutions of Example 1 and Conventional Example 1, Example 2 and Conventional Example 2, Example 3 and Conventional Example 3 and Conventional Example 4, and Example 6 and Conventional Example 5, respectively. The difference is remarkable. That is, the aluminum electrolytic capacitors using Examples 1 to 3 and 6 have a tan δ of about 4 as compared with those using Conventional Examples 1 to 5.
The leakage current is 7.3 to 66.7% and the leakage current is 6.9 to 17%.

After standing for 5000 hours, the aluminum electrolytic capacitors impregnated with the electrolytic solutions of Examples 1 to 8 have a tan δ of 0.045 to 0.091 and a leakage current of 20 to 40 μA. That is, tan δ is almost the same as the initial value and the leakage current is smaller than the initial value. On the other hand, in the aluminum electrolytic capacitors impregnated with the electrolytic solutions of Conventional Example 1 to Conventional Example 5, all the explosion-proof valves of the samples were activated, and the characteristics could not be measured.

Comparing the aluminum electrolytic capacitors impregnated with the electrolytic solutions of Examples 3 to 5, the smaller the amount of trehalose added, the better the tan δ and the leakage current.

[0018]

As described above, according to the present invention, by containing trehalose, it is possible to obtain the electrolytic solution for an electrolytic capacitor which can improve the tan δ characteristic and the leakage current characteristic of the electrolytic capacitor and can prolong its life.

Claims (1)

[Claims] 1. An electrolytic solution for an electrolytic capacitor in which at least one kind of organic acid, organic acid salt, boric acid or borate is dissolved using a polyhydric alcohol as a main solvent, and trehalose is contained. Electrolytic solution for electrolytic capacitors.