JPH01114026A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve loss characteristic of a capacitor and to increase its life at a high temperature by employing electrolyte in which protochatechuic acid or its salt is added to be decomposed with tetramethyl/ethylammonium salt of phthalic acid or maleic acid is dissolved as solute in solvent which contains as main body gamma-butyrolactone. CONSTITUTION:Tetramethylammonium salt of phthalic acid, tetraethylammonium salt, tetramethylammonium salt of maleic acid or tetraethylammonium salt is dissolved as solute in solvent which contains as main body gamma-butyrolactone, and 0.01-10wt.% protochatechic acid or its salt is further added as additive thereto. Thus, a dielectric oxide film is protected to suppress a reduction in its electrostatic capacity and an increase in its dielectric loss. Accordingly, the loss characteristic of a capacitor is improved, it is stable at a high temperature with long life.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to electrolytic capacitors, 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 has poor characteristics at low temperatures. In order to improve the above-mentioned drawbacks,
1-70711, using γ-butyrolactone as a solvent and triethylamine salt of 7-talic acid, and JP-A-54-7564, using γ-butyrolactone and ethylene glycol. There is an example of using an amine salt of maleic acid as a mixed solvent.

Problems to be Solved by the Invention However, as a conventional problem, γ-butyrolactone is
No. 18, when triethylamine salt of phthalic acid is used, the specific conductivity is low and, although it shows high stability at 106°C, it is not very stable at 126°C. Furthermore, when an amine salt of maleic acid is used in a mixed solvent of γ-butyrolactone and ethylene glycol, a sufficiently high value of specific conductivity can be obtained, but it lacks stability at high temperatures and
It has the disadvantage of low stability even at 06°C.

The present invention solves these conventional drawbacks, and aims to provide an electrolytic solution with high conductivity and little deterioration at high temperatures, and to improve the loss characteristics of electrolytic capacitors and extend their life at high temperatures. .

Means for Solving the Problems In order to solve these problems, the present invention provides a method for adding tetramethylammonium salt or tetraethylammonium salt of phthalic acid, or tetramethylammonium maleic acid to a solvent mainly composed of γ-butyrolactone. This is an electrolytic solution for driving an electrolytic capacitor that uses ammonium salt or tetraethylammonium salt dissolved as a solute and protocatechuic acid or its salt as an additive.

The amount of protocatechuic acid or its salt added is preferably 0.01 to 10% by weight based on the weight of the electrolyte. This is because if it is less than 0.01% by weight, there is no effect, and if it exceeds 10% by weight, the conductivity will be significantly lowered.

Effect When a solvent mainly composed of γ-butyrolactone is combined with a tetramethylammonium salt or a tetraethylammonium salt of phthalic acid or a tetramethylammonium salt or a tetraethylammonium salt of maleic acid as a solute, high conductivity can be obtained. can get.

When the solvent is mainly composed of γ-butyrolactone, phthalic acid and maleic acid are difficult to decompose at high temperatures, and reactions with tetramethylammonium or tetraethylammonium are also difficult to occur. Therefore, it is thought that an electrolytic solution with extremely low change in properties at high temperatures can be obtained.

Furthermore, it is considered that protocatechuic acid adsorbs to the surface of the aluminum electrode foil and protects the dielectric oxide film, thereby significantly suppressing the decrease in capacitance and the increase in -δ.

Example Examples according to the present invention will be described below.

Table 1 shows examples of the present invention, examples of conventional electrolyte compositions, and specific conductivities at room temperature.

Table 1 Electrolyte composition and specific conductivity of Example and Conventional Example □
-'' As is clear from Table 1, a higher specific conductivity can be obtained compared to conventional electrolytes.

Table 2 shows the initial characteristics of capacitors using the electrolytes of the conventional example and example shown in Table 1. Sample capacitor is 8.3V1
oooμF (φ10X12.5) (7) This is a Fulmi electrolytic capacitor.

Table 2 Initial Characteristic Comparison As is clear from Table 2, the example has a t
anδ can be lowered.

Figures 1 to 3 show changes in characteristics over time at 125°C of the aluminum electrolytic capacitors shown in Table 2. FIG. 1 shows the capacitance change when the rated voltage is applied, FIG. 2 shows the loss angle tangent change when the rated voltage is applied, and FIG. 3 shows the leakage current change when no voltage is applied.

As is clear 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, it is possible to provide a highly reliable electrolytic capacitor that can improve loss characteristics compared to conventional electrolytes and is extremely stable even at high temperatures of 125°C, and has industrial value. It is a great thing.

[Brief explanation of the drawing]

Figures 1 to 3 show a rated 6.3V 1000μF (φ1ox
12.5) shows the change in characteristics over time at 125°C of the aluminum electrolytic capacitor. Figure 1 is a characteristic diagram showing the capacitance change when the rated voltage is applied, and Figure 2 is the characteristic diagram showing the change in capacitance when the rated voltage is applied. FIG. 3 is a characteristic diagram showing changes in tangent, and FIG. 3 is a characteristic diagram showing changes in leakage current when no voltage is applied. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 x% 7'? + <hrs) 3rd゜ ``Yoran゛Drunken゛2 ``H41%j (hrs)

Claims (2)

[Claims] (1) Protocatechuic acid or its salt was added and dissolved in a solvent mainly composed of γ-butyrolactone, with tetramethylammonium salt or tetraethylammonium salt of phthalic acid, or tetramethylammonium salt or tetraethylammonium salt of maleic acid as a solute. An electrolytic solution for driving an electrolytic capacitor, which is characterized by: (2) The electrolyte solution for driving an electrolytic capacitor according to claim 1, wherein the amount of protocatechuic acid or its salt added is 0.01 to 10% by weight based on the weight of the electrolyte solution.