JPH08264389A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE: To provide an electrlytic capacitor for medium and high voltages use wherein the corrosion of a capacitor element caused by immersion of halogenated hydrocarbon is prevented by adding a nitro compound which has no hydroxyl group nor carboxyl group and which has a stable characteristic even at high temperatures without the decline in sparking voltage even with the addition of the nitro compound. CONSTITUTION: In an electrolyte for driving a capacitor wherein a solvent, chief of which is ethylene glycol and/or diethylene glycol, is used as a solvent and a solute which is made from organic carboxylic acid or boric acid or from organic carboxylic acid and boric acid (at least one acid is used as a form of a salt) is dissolved, 0.1wt.% or above of a nitro compound which has no hydroxyl group nor carboxyl group is added.

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 driving an electrolytic capacitor, and more particularly to improving the characteristics of an electrolytic capacitor for medium and high voltages.

[0002]

2. Description of the Related Art Heretofore, an electrolytic solution prepared by dissolving an organic carboxylic acid, boric acid, or a salt thereof in a solvent mainly composed of ethylene glycol has been used as an electrolytic solution for driving a medium-high voltage electrolytic capacitor. In the middle and high voltage electrolytic capacitors, there is an increasing demand for cleaning with halogenated hydrocarbons. To meet this demand, measures have been taken to add nitro compounds such as para-nitrophenol and para-nitrobenzoic acid to these electrolytic solutions for the purpose of preventing corrosion of capacitor elements.

However, since these nitro compounds have a hydroxyl group and a carboxyl group, they themselves act as an electrolyte, so that the electrolytic solution added with them remarkably lowers the spark voltage, and during aging. Application to medium- and high-voltage electrolytic capacitors, such as puncture, has a problem in terms of withstand voltage.

[0004]

As described above, when the conventional electrolytic capacitor is soldered and mounted on the printed board, it is cleaned by vaporizing with halogenated hydrocarbon for the purpose of removing the solder flux during the process. However, halogenated hydrocarbons sometimes penetrated the sealing material of the electrolytic capacitor and penetrated into the inside of the capacitor to decompose, generating chlorine ions and corroding the capacitor element. Although a nitro compound has been added to the driving electrolyte solution for the purpose of preventing this corrosion, it causes a decrease in spark voltage and thus has a problem in withstand voltage characteristics.

The present invention was made in order to solve the above problems, and suppresses corrosion of capacitor elements caused by infiltration of halogenated hydrocarbons, and does not cause reduction in spark voltage. It is intended to provide an electrolytic solution for driving a capacitor.

[0006]

According to the present invention, in the invention described in claim 1, a solvent containing ethylene glycol and / or diethylene glycol as a main component and at least one of organic carboxylic acid and / or boric acid is a salt thereof. The electrolyte for driving an electrolytic capacitor, characterized in that 0.1% by weight or more of a nitro compound having neither a hydroxyl group nor a carboxyl group is added to a driving electrolyte in which a solute is dissolved. The nitro compound having no hydroxyl group or carboxyl group in the driving electrolyte according to claim 1 is nitroacetophenone, nitroacetanilide, nitrobenzamide, nitrobenzaldehyde, nitroanisole, nitroaniline, nitrobenzene, nitrophenetole, nitrophenylenediamine,
Nitrophenylhydrazine, 1 of nitronaphthalene
It is an electrolytic solution for driving an electrolytic capacitor, which is one kind or a mixture of two or more kinds.

[0007]

According to the electrolytic solution for driving an electrolytic capacitor configured as described above, at least one of a solvent containing ethylene glycol and / or diethylene glycol as a main component and an organic carboxylic acid and / or boric acid is a salt thereof. By adding 0.1% by weight or more of a nitro compound having no hydroxyl group and carboxyl group to a driving electrolyte solution in which a solute is dissolved, corrosion due to intrusion of halogenated hydrocarbons is suppressed, and spark voltage is reduced. It is possible to provide a highly reliable electrolytic solution for driving an electrolytic capacitor for medium and high voltages, which does not decrease.

The reason why the addition amount of the nitro compound having no hydroxyl group or carboxyl group is 0.1% by weight or more is that if the amount is less than 0.1% by weight, the corrosion due to the penetration of halogenated hydrocarbon cannot be suppressed. This is because it has no effect. In addition, the upper limit of the addition amount of the nitro compound having no hydroxyl group or carboxyl group can be added within the range until the precipitation of these nitro compounds.

[0009]

EXAMPLES Examples of the electrolytic solution for driving an electrolytic capacitor according to the present invention will be described below. That is, in Example A, the composition, specific resistance, and spark generation voltage characteristics of the driving electrolytic solution are shown, and in Example B, the initial stage of the electrolytic capacitor manufactured using the driving electrolytic solution shown in Example A is shown. The values and the characteristic values after performing the high temperature load test after cleaning the halogenated hydrocarbon in steam are shown.

Example A Table 1 shows the compositions of the driving electrolyte solutions of Conventional Examples 1 to 3, Examples 1 to 11 and Reference Example 1, and Table 2 shows the specific resistance of these driving electrolyte solutions at 25 ° C. , And the spark generation voltage.

[0011]

[Table 1]

[0012]

[Table 2]

As is clear from Table 2, in the examples in which the nitro compound having no hydroxyl group or carboxyl group was added, the spark generation voltage could be increased by 30 to 50 V with almost no change in the specific resistance.

Example B Rated 450 V-150 μF manufactured by using each of the driving electrolytic solutions of the conventional example, the example and the reference example shown in the above-mentioned Example A.
Table 3 shows the initial values of 20 aluminum electrolytic capacitors each.
In addition, halogenated hydrocarbons (1,1,2-trichloro-
Table 4 shows the characteristics after a high temperature load test of 105 ° C.-1000 h was performed after cleaning in a steam of 1,2,2-trifluoroethane for 5 minutes.

[0015]

[Table 3]

[0016]

[Table 4]

After the test was completed, as a result of disassembling the electrolytic capacitor used as a sample, the corroded samples except for Conventional Example 3 and Reference Example 1 in which the explosion-proof valve operated during aging were zero in both the Conventional Example, Example and Reference Example. Met. This is because a nitro compound having neither a hydroxyl group nor a carboxyl group is added to these electrolytic solutions in an appropriate amount range.

As is clear from Tables 3 and 4, in Examples 1 to 11 using the driving electrolyte solution of the present invention, compared with Conventional Examples 1 to 3 using the conventional driving electrolyte solution, There is no explosion-proof valve operation during aging as in Conventional Example 3 at the initial stage, and since the spark voltage is high, the leakage current and tan δ are also small. Further, even after the high temperature load test, the rate of change in capacity, the change in tan δ, and the change in leakage current were significantly small, and the valve swelled in the conventional example in appearance, but none in the example. In Reference Example 1 in which the amount of nitro compound of the same type as in Example 3 is small, the explosion-proof valve operates during aging, but this is because the amount of nitro compound added is as small as 0.05% by weight, and therefore corrosion This is a result of the increase in pressure inside the capacitor case due to the hydrogen gas generated by.

In the present invention, the addition amount range of the nitro compound having no hydroxyl group or carboxyl group is set to 0.1.
Although the amount is not less than wt%, it may be added in the range of 0.1 wt% to the occurrence of the precipitation phenomenon of the nitro compound.

[0020]

As described above, the electrolytic solution for driving an electrolytic capacitor according to the present invention suppresses corrosion due to infiltration of halogenated hydrocarbons and increases the spark generation voltage without increasing the specific resistance. Therefore, it is possible to provide a long-life electrolytic capacitor for medium and high voltages, which has stable characteristics even at high temperatures.

Claims (2)

[Claims] 1. A driving electrolytic solution in which a solvent containing ethylene glycol and / or diethylene glycol as a main component and a solute in which at least one of organic carboxylic acid and / or boric acid is a salt thereof is dissolved is added with a hydroxyl group and a carboxyl group. An electrolytic solution for driving an electrolytic capacitor, which is obtained by adding 0.1% by weight or more of a nitro compound having no hydrogen. 2. A nitro compound having no hydroxyl group or carboxyl group is nitroacetophenone, nitroacetanilide, nitrobenzamide, nitrobenzaldehyde, nitroanisole, nitroaniline, nitrobenzene, nitrophenetol, nitrophenylenediamine, nitrophenylhydrazine, nitronaphthalene. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the electrolytic solution is one kind or a mixture of two or more kinds.