JPH07120615B2 - Electrolytic solution for driving electrolytic capacitors - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor, and more specifically to an electrolytic solution for driving an aluminum electrolytic capacitor.

2. Description of the Related Art Conventionally, as an electrolytic solution for driving an electrolytic capacitor, an electrolytic solution in which ionogen is dissolved in ethylene glycol has been used. This type of electrolytic capacitor deteriorates the characteristics at low temperatures. In order to improve the above drawbacks, JP-A-61
As disclosed in JP-A-70711, an example using γ-butyrolactone as a solvent and a triethylamine salt of phthalic acid, and, as seen in JP-A-54-7564, a mixed solvent of γ-butyrolactone and ethylene glycol. There is an example of using an amine salt of maleic acid.

Problems to be Solved by the Invention However, as a conventional problem, when γ-butyrolactone is used as a solvent and a triethylamine salt of phthalic acid is used,
It has a low specific conductivity and high stability at 105 ° C, but is not very stable at 125 ° C.
Further, when the amine salt of maleic acid is used as the mixed solvent of γ-butyrolactone and ethylene glycol, the specific electric conductivity can be obtained at a sufficiently high value, but the stability at high temperature is poor and the stability is low even at 105 ° C. There is.

The present invention solves such conventional drawbacks, and an object thereof is to provide an electrolytic solution having high conductivity and little deterioration at high temperature, aiming at improvement of loss characteristics of an electrolytic capacitor and at the same time prolonging its life at high temperature. To do.

Means for Solving the Problems In order to solve the above problems, the present invention, in a solvent containing γ-butyrolactone as a main component, a tetramethylammonium salt of maleic acid or a tetraethylammonium salt as a solute, An electrolytic solution for driving an electrolytic capacitor, which uses an alkyl phosphate ester or a salt thereof and / or P-nitrobenzoic acid or a salt thereof as an additive.

Although the effect can be recognized by using any alkyl group of the alkyl phosphate ester, preferably, monoethyl phosphate ester, monopropyl phosphate ester, monobutyl phosphate ester, monopentyl phosphate ester,
Diethyl phosphate ester, dipropyl phosphate ester,
Dibutyl phosphate ester, dipentyl phosphate ester and salts thereof.

The addition amount of the alkyl phosphate or its salt is preferably 0.01 to 5.0% by weight with respect to the amount of the electrolytic solution. This is 0.0
This is because if the amount is less than 1% by weight, there is no effect, and if the amount exceeds 5.0% by weight, the decrease in electrical conductivity becomes large.

The amount of P-nitrobenzoic acid or its salt added is preferably 0.01 to 5.0% by weight based on the amount of the electrolytic solution. This is because if the amount is less than 0.01% by weight, there is no effect, and if the amount exceeds 5.0% by weight, the spark voltage decreases.

Action When a solvent mainly composed of γ-butyrolactone is combined with a tetramethylammonium salt of maleic acid or a tetraethylammonium salt as a solute, an extremely high degree of electrical life can be obtained.

When the solvent is mainly composed of γ-butyrolactone, maleic acid is relatively hard to decompose at high temperature, and the reaction with tetramethylammonium or tetraethylammonium hardly occurs. Therefore, it is considered that an electrolytic solution with extremely low characteristic changes at high temperatures can be obtained.

Further, alkyl phosphate or P-nitrobenzoic acid is adsorbed on the surface of the aluminum electrolytic foil to protect the dielectric oxide film, thereby reducing the capacitance and increasing tan δ.
It is considered that the increase of the can be significantly suppressed.

Examples Hereinafter, examples according to the present invention will be described.

Table 1 shows examples of the present invention, conventional electrolytic solution composition examples, and specific electric conductivity at room temperature.

As is clear from Table 1, a higher specific electric conductivity can be obtained as compared with the conventional electrolytic solution.

Table 2 shows initial characteristics of capacitors using the electrolytic solutions of Conventional Example 1, Conventional Example 2, Example 1, Example 2, Example 3 and Example 6 of Table 1. Sample capacitor is 6.3V 1000μF
(Φ10 × 12.5) aluminum electrolytic capacitor.

As is clear from Table 2, the embodiment has a ta
nδ can be lowered.

Figures 1 to 3 show the changes over time in the characteristics of the aluminum electrolytic capacitors shown in Table 2 at 125 ° C. Figure 1 shows the change in capacitance when rated voltage is applied, and Figure 2 shows when the rated voltage is applied. Change in tangent of loss angle, and FIG. 3 is a view showing change in leakage current without application of voltage.

As is apparent from FIGS. 1 to 3, the change in characteristics is extremely small even at high temperatures, and a highly reliable capacitor can be obtained.

EFFECTS OF THE INVENTION As described above, according to the present invention, loss characteristics can be improved as compared with conventional electrolytic solutions, and an extremely stable and highly reliable electrolytic capacitor can be provided even at a high temperature of 125 ° C. Is a great thing.

[Brief description of drawings]

FIGS. 1 to 3 show characteristics of the aluminum electrolytic capacitors rated at 6.3V and 1000 μF (φ10 × 12.5) using the conventional electrolytic solution and the electrolytic solution of the present invention with time at 125 ° C., respectively. FIG. 2 is a characteristic diagram showing a change in capacitance when a rated voltage is applied, FIG. 2 is a characteristic diagram showing a tangent change in loss angle when a rated voltage is applied, and FIG.

Claims (4)

[Claims] 1. A solvent containing γ-butyrolactone as a main component,
An electrolytic solution for driving an electrolytic capacitor, characterized in that a tetramethylammonium salt or a tetraethylammonium salt of maleic acid is used as a solute, and an alkyl phosphate ester or a salt thereof and / or P-nitrobenzoic acid or a salt thereof is added and dissolved. 2. An alkyl phosphoric acid ester having the following (A),
The electrolytic solution for driving an electrolytic capacitor according to claim 1, which has a chemical structure as shown in (B). 3. The electrolytic solution for driving an electrolytic capacitor according to claim 2, wherein the addition amount of the alkyl phosphate or its salt is 0.01 to 5.0% by weight based on the weight of the electrolytic solution. 4. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the added amount of P-nitrobenzoic acid or its salt is 0.01 to 5.0% by weight based on the weight of the electrolytic solution. .