JPH10256093A - Driving electrolyte for electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of driving electrolyte by employing a salt of 4-imidazolone group shown by a specific formula as a solute. SOLUTION: A driving electrolyte employing a salt of 4-imidazolones shown by a formula (in the formula, R1 , R2 and R3 are selected, respectively, from hydrogen and alkyl group of 1-3C) as a solute is used. Salt of 4-imidazolones can be selected freely and a salt of organic carboxylic acid, e.g. phthalic acid or maleic acid, is preferably employed. Furthermore, a solvent principally comprising one or two kind of material selected from γ-butyrolactone and ethylene glycol is preferably employed. According to the arrangement, leakage of driving electrolyte can be eliminated.

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.

[0002]

2. Description of the Related Art An aluminum electrolytic capacitor is formed by encapsulating a capacitor element formed by winding an aluminum electrode foil together with a driving electrolyte in a case. As the case of such an aluminum electrolytic capacitor, a case of an upper opening type is generally used, and the upper opening is closed by a rubber sealing member. Extraction of the electrode from the capacitor element housed in the case is generally performed by connecting the extraction terminal of the capacitor element to a rivet that penetrates a rubber sealing member. Is composed of aluminum.

As an electrolyte for driving such an aluminum electrolytic capacitor, an electrolyte obtained by dissolving an organic carboxylic acid and boric acid or a salt thereof in a solvent mainly composed of ethylene glycol has been used. Was.
On the other hand, in recent years, as the impedance of the electrolytic capacitor has been reduced, the demand for lowering the resistance of the driving electrolyte has also increased, so that a solvent mainly composed of γ-butyrolactone has been added to an organic carboxylic acid such as phthalic acid or maleic acid. An electrolytic solution in which a quaternary ammonium salt is dissolved is used. As described above, an electrolytic solution containing a quaternary ammonium salt of an organic carboxylic acid as a solute has the advantages of low specific resistance and stability even at high temperatures.

[0004]

However, as described above, when a driving electrolyte containing a quaternary ammonium salt of an organic carboxylic acid such as phthalic acid or maleic acid as a solute is used, the use of an electrolytic capacitor at the time of using an electrolytic capacitor is difficult. The driving electrolyte near the cathode becomes strongly alkaline. And in this case,
The strongly alkaline driving electrolyte degrades the rubber sealing member that seals the opening of the electrolytic capacitor, the aluminum lead-out terminal and rivets fixed to it, and the cathode of the rubber sealing member degrades. There is a possibility that a problem that the driving electrolyte leaks from the portion may occur, and there is a problem in reliability.

As described above, when a conventional electrolytic solution for driving an electrolytic capacitor using a quaternary ammonium salt as a solute is used, the specific resistance and the stability at a high temperature are excellent, but the use of the electrolytic capacitor is high. Occasionally, the driving electrolyte near the cathode becomes strongly alkaline, causing a problem that the driving electrolyte inside the rubber leaks from the cathode of the sealing member to the outside. There is.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide an electrolytic capacitor which has a sufficiently small specific resistance and is stable even at high temperatures. By providing a highly reliable electrolytic solution for driving an electrolytic capacitor, the vicinity of the cathode sometimes does not become strongly alkaline, and the problem that the driving electrolyte leaks due to deterioration of the member due to the strong alkali does not occur. is there.

[0007]

The electrolyte for driving an electrolytic capacitor according to the present invention uses a salt of a 4-imidazolone as a solute instead of the conventional quaternary ammonium salt. That is, the electrolytic solution for driving an electrolytic capacitor according to claim 1 is characterized in that a salt of a 5-imidazolone represented by the following general formula (1) is used as a solute.

[0008]

Embedded image

However, in the formula (1), R1, R2, R
Each of 3 is selected from hydrogen and an alkyl group having 1 to 3 carbon atoms.

The driving electrolyte containing a salt of a 4-imidazolone represented by the general formula (1) as a solute has a sufficiently small specific resistance as in the case of using a quaternary ammonium salt as a solute. Stable even at high temperatures. In addition, unlike a case where a quaternary ammonium salt is used as a solute, a driving electrolyte using a salt of a 4-imidazolone as a solute does not become strongly alkaline near a cathode when an electrolytic capacitor is used. And aluminum drawer terminals and rivets are not deteriorated. Therefore, it is possible to prevent a problem that the driving electrolyte leaks due to the deterioration of these members.

The 4-imidazolone used in the electrolytic solution for driving an electrolytic capacitor according to the first aspect is, specifically, one selected from the group of the 4-imidazolones according to the second aspect. Or two or more. That is, this group of 4-imidazolones includes 4-imidazolone, 1-methyl-4-imidazolone, 1,5-
Dimethyl-4-imidazolone, 1-ethyl-4-imidazolone, 1,5-diethyl-4-imidazolone, 1-propyl-4-imidazolone, 1,5-dipropyl-4-
A group consisting of imidazolone and 1,2,5-trimethyl-4-imidazolone.

Further, in the electrolytic solution for driving an electrolytic capacitor according to the first or second aspect, salts of 4-imidazolones can be arbitrarily selected. In particular, as described in the third aspect, phthalic acid or maleic acid is used. It is desirable to use salts of organic carboxylic acids such as acids.

On the other hand, in the electrolytic solution for driving an electrolytic capacitor according to any one of the first to third aspects, any solvent can be used. It is desirable to use a solvent mainly composed of one or two materials selected from butyrolactone and ethylene glycol.

[0014]

EXAMPLES Examples of the electrolytic solution for driving an electrolytic capacitor according to the present invention will be described below. First, Table 1 shows Examples 1 to 8 of the driving electrolyte using a salt of a 4-imidazolone as a solute according to the present invention and conventional driving electrolytes using a quaternary ammonium salt as a solute according to the related art. The compositions of Examples 1 and 2 are shown.

[0015]

[Table 1]

Next, Table 2 shows conventional examples 1 and 2 as described above.
5 shows the test results obtained by examining the specific resistance and the spark generation voltage at 25 ° C. for each of the driving electrolytes of Examples 1 to 8 according to the present invention. Also, in Table 2, 20 aluminum electrolytic capacitors of the same rating manufactured using the respective driving electrolytes of Conventional Examples 1 and 2 and the respective driving electrolytes of Examples 1 to 8 according to the present invention. (25V-10
00 μF) in a closed container under a high-temperature load test (105 ° C., 2,000 hours) under the same conditions, and the result of observing liquid leakage at the sealing portion is also shown.

[0017]

[Table 2]

As apparent from Table 2, each of the driving electrolytes of Examples 1 to 8 according to the present invention has a specific resistance sufficient to the same extent as each of the driving electrolytes of Conventional Examples 1 and 2. And the spark generation voltage is higher than that of the conventional examples 1 and 2. That is, Conventional Examples 1 and 2
Has a specific resistance of 95 to 105 Ωcm, whereas the specific resistance of Examples 1 to 8 according to the present invention is 90 to 105 Ωcm, which is sufficiently small to the same level as or less than the conventional example. While the spark generation voltage of the conventional examples 1 and 2 is 80 to 110 V, the first embodiment according to the present invention.
8 are 110 to 140 V, which are clearly higher than those of Conventional Examples 1 and 2.

Regarding the high-temperature load test in a closed container, the aluminum electrolytic capacitor using each of the driving electrolytes of Conventional Examples 1 and 2 has 15 or 1 out of 20 capacitors.
Six, and more than half, have leaked. On the other hand, in the aluminum electrolytic capacitor using each of the driving electrolytes of Examples 1 to 8 according to the present invention, there is no liquid leakage.

[0020] When the driving electrolyte according to the present invention is used, it is considered that the liquid leakage can be prevented for the following reasons. That is, since each of the driving electrolytes of Examples 1 to 8 uses a salt of a 4-imidazolone as a solute, each of the driving electrolytes of Conventional Examples 1 and 2 using a quaternary ammonium salt as a solute is used. Unlike the case where the electrolytic capacitor is used, the vicinity of the cathode does not become strongly alkaline when the electrolytic capacitor is used, so that the rubber sealing member, the aluminum lead-out terminal, the rivet and the like do not deteriorate.

As described above, Embodiments 1 to 8 according to the present invention
Each of the driving electrolytes can prevent the occurrence of a problem that the driving electrolyte leaks out, and has extremely high reliability as compared with the driving electrolytes of Conventional Examples 1 and 2.

The present invention is not limited to Examples 1 to 8, and the specific composition of the electrolytic solution can be appropriately selected within the scope of the present invention. For example, the first embodiment
In Nos. To 8, only one selected from the group of 4-imidazolones according to claim 2 was used.
It is also possible to use more than one species, in which case also excellent effects can be obtained.

Further, in the above Examples 1 to 8, the case where only one of the salt of phthalic acid and the salt of maleic acid was used was described, but both the salt of phthalic acid and the salt of maleic acid were used. The same effect can be obtained, and in this case, similarly excellent effects can be obtained. Further, salts of 4-imidazolones can be arbitrarily selected, but usually, it is desirable to use salts of organic carboxylic acids such as phthalic acid and maleic acid as in Examples 1 to 8.

In the above Examples 1 to 8, the case where only γ-butyrolactone was used as the solvent and the case where both γ-butyrolactone and ethylene glycol were used were explained. It is also possible to use other materials than γ-butyrolactone and ethylene glycol. However, basically, as in Examples 1 to 8, it is desirable to use a solvent mainly composed of one or two materials selected from γ-butyrolactone and ethylene glycol.

On the other hand, in the first to eighth embodiments, the case where the present invention is applied to an aluminum electrolytic capacitor having a rating of 25 V-1000 μF has been described. However, the driving electrolyte of the present invention is applicable to various electrolytic capacitors having various ratings. The same is applicable, and in any case, the first embodiment is used.
As in the case of Nos. To 10, excellent effects can be obtained.

[0026]

As described above, according to the present invention, by using a salt of a 4-imidazolone as a solute instead of the conventional quaternary ammonium salt, the specific resistance is sufficiently small and stable at high temperatures. In addition, a highly reliable electrolytic capacitor that does not become strongly alkaline near the cathode when using the electrolytic capacitor and does not cause a problem that the driving electrolyte leaks due to deterioration of the member due to the strong alkali. A driving electrolyte can be provided.

Claims (4)

[Claims] 1. An electrolytic capacitor driving electrolyte sealed in a case together with a capacitor element, wherein a salt of a 4-imidazolone represented by the following general formula (1) is used as a solute. Electrolyte. Embedded image However, in this formula (1), each of R1, R2, and R3 is
It is selected from hydrogen and an alkyl group having 1 to 3 carbon atoms. 2. The method according to claim 1, wherein the 4-imidazolone is 4-imidazolone, 1-methyl-4-imidazolone, 1,5-dimethyl-4-imidazolone, 1-ethyl-4-imidazolone, 1,5-diethyl-4-. It is one or more selected from imidazolone, 1-propyl-4-imidazolone, 1,5-dipropyl-4-imidazolone, 1,2,5-trimethyl-4-imidazolone. The electrolytic solution for driving an electrolytic capacitor according to claim 1. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the salt of the 4-imidazolone is a salt of an organic carboxylic acid. 4. The solvent according to claim 1, wherein the solvent is a solvent mainly composed of one or two materials selected from γ-butyrolactone and ethylene glycol. 3. The electrolytic solution for driving an electrolytic capacitor according to item 1.