JPH08335533A - Electrolytic solution for driving electrolytic capacitors - Google Patents

Abstract

(57) [Abstract] [Purpose] To construct a capacitor that has stable characteristics in a wide temperature range, has a long life, and is highly reliable, and that can be used even at a higher voltage than before. An electrolytic solution for driving an electrolytic capacitor is provided. [Structure] In a solvent mainly composed of γ-butyrolactone,
Tetramethylammonium 2,3-dihydroxybenzoate, tetramethylammonium 2,4-dihydroxybenzoate, tetraethylammonium 2,5-dihydroxybenzoate, tetramethylammonium 2,6-dihydroxybenzoate, 3,4-dihydroxybenzoic acid Dissolve tetraethylammonium or tetramethylammonium 3,5-dihydroxybenzoate as a solute. The nitro compounds nitrophenol, nitrobenzoic acid, nitroacetophenone or nitroaniline are added as additives.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention aims to reduce the resistance of an electrolytic capacitor and to increase the withstand voltage, so that the solvent used is γ-.
The present invention relates to an electrolytic solution for driving an electrolytic capacitor, which is mainly composed of butyrolactone and has improved solutes and additives dissolved therein.

[0002]

2. Description of the Related Art Electrolytic capacitors are one of the important components of various electric and electronic devices. In particular, as the performance of communication equipments and measuring equipments has increased, it has been required to improve the characteristics and extend the life of low voltage aluminum electrolytic capacitors incorporated in these equipments. Generally, an aluminum electrolytic capacitor is formed by using an aluminum foil having an oxide film formed on its surface as an anode, and using this oxide film as a dielectric to hold a driving electrolytic solution with a separator interposed between the aluminum foil and a collector cathode. Has been done. Since the driving electrolyte directly contacts the dielectric and acts as a substantial cathode, the characteristics of the electrolytic capacitor greatly depend on the characteristics of the driving electrolyte used.

The driving electrolytic solution for such a low voltage electrolytic capacitor has conventionally used ethylene glycol as a solvent and an organic carboxylic acid such as adipic acid as a solute. Then, in order to maintain the reliability by lowering the specific resistance of the electrolytic solution and lowering the pH, the electrolytic solution contains water of several wt%.

Further, in the electrolytic capacitor as described above, hydrogen gas is generated due to the reaction between the driving electrolytic solution and the electrodes or with the leakage current. This hydrogen gas raises the pressure inside the case and actuates the explosion-proof valve provided on the lid, so that the less the generation of hydrogen gas, the longer the life of the electrolytic capacitor. Further, the electrolytic capacitor is cleaned with halogenated hydrocarbon for removing the solder flux after being soldered onto the printed circuit board. At this time, when the halogenated hydrocarbon that has entered the electrolytic capacitor is decomposed by heat or the like to release chlorine ions, the aluminum of the electrode foil is corroded. In order to suppress the generation of hydrogen gas and the decomposition of halogenated hydrocarbons as described above,
A nitro compound such as metanitroacetophenone is added to the driving electrolyte.

[0005]

However, as described above, the driving electrolytic solution using the organic carboxylic acid such as adipic acid in ethylene glycol as a solute has a problem in that the viscosity is increased in a low temperature range. However, there are problems such as an increase in specific resistance in a high temperature region or an increase in loss accompanying it.

Therefore, in recent years, in order to improve the characteristics at low temperatures, those in which γ-butyrolactone is mainly used as a solvent and a salt of maleic acid or phthalic acid is used as a solute have been developed. Such an electrolytic capacitor driving electrolytic solution solves problems such as an increase in viscosity in a low temperature region, an increase in specific resistance in a high temperature region, and an increase in loss accompanying it.

However, the electrolytic solution for driving the electrolytic capacitor has a problem that the spark generation voltage becomes low. In other words, the phenomenon in which the electrochemical state of the electrolytic capacitor fluctuates as a result of the increase in load voltage, the change in the physical properties of the dielectric material, and the change in the dielectric constant is called scintillation. Although the spark generation voltage (scintillation voltage) is used, when a salt of maleic acid or phthalic acid is used as a solute, the spark generation voltage of the electrolytic solution is low. The higher the spark generation voltage, the higher the withstand voltage of the electrolytic capacitor.
Solutes such as those mentioned above can affect the reliability of the electrolytic capacitors in which they are used.

Further, since the electrolytic solution using the salt of maleic acid or phthalic acid as a solute has a low spark generation voltage, it can be used only in a low voltage capacitor of 50 V class or less, and its application range is limited. It will be.

The present invention has been proposed to solve the problems of the prior art, and an object thereof is to provide a capacitor having stable characteristics in a wide temperature range, long life and high reliability. An object of the present invention is to provide an electrolytic solution for driving an electrolytic capacitor, which can be configured and can be configured as a capacitor that can be used even at a higher voltage than before.

[0010]

In order to achieve the above object, the invention according to claim 1 is an electrolytic capacitor driving electrolytic solution using a solvent mainly comprising γ-butyrolactone, which is dissolved in the solvent. The solute is mainly composed of a tetramethylammonium salt of dihydroxybenzoic acid or a tetraethylammonium salt of dihydroxybenzoic acid.

The invention according to claim 2 is characterized in that at least one of nitrophenol, nitrobenzoic acid, nitroaniline and nitroacetophenone is added.

[0012]

The operation of the present invention having the above construction is as follows. That is, in the invention according to claim 1, the solvent constituting the electrolytic solution is mainly γ-butyrolactone,
Since the solute is mainly composed of tetramethylammonium salt or tetraethylammonium salt of dihydroxybenzoic acid, the specific resistance of the electrolytic solution becomes low. Further, with such a composition, the characteristics of the electrolytic solution are stable even at high temperatures, and the spark generation voltage increases.

According to the second aspect of the present invention, the added nitro compound suppresses hydrogen gas generated by the reaction between the driving electrolytic solution and the electrode or due to the leakage current, so that the halogenated hydrocarbon of Since the decomposition is suppressed, the characteristics of the electrolytic solution are stable for a long period of time.

[0014]

EXAMPLES Examples of the electrolytic solution for driving an electrolytic capacitor according to the present invention will be described below. Here, Examples 1 to 6 were prepared as electrolytic solutions for driving electrolytic capacitors having different compositions. For comparison with these examples, Comparative Examples 1 to 3 having different composition types were used as electrolytic solutions for driving electrolytic capacitors according to the prior art.
Was produced.

(1) Composition First, the composition materials and their ratios constituting Examples 1 to 6 and Comparative Examples 1 to 3 are shown below.

In Examples 1 to 6, γ was used as the solvent.
-Mainly composed of butyrolactone. The main solutes are tetramethylammonium 2,3-dihydroxybenzoate, tetramethylammonium 2,4-dihydroxybenzoate, tetraethylammonium 2,5-dihydroxybenzoate, tetramethylammonium 2,6-dihydroxybenzoate. 3,4-dihydroxybenzoic acid tetraethylammonium or 3,5-dihydroxybenzoic acid tetramethylammonium is used. Furthermore, nitrophenol, nitrobenzoic acid, nitroacetophenone or nitroaniline is used as the additive nitro compound.

[Example 1] γ-butyrolactone 79 wt% 2,3-dihydroxybenzoic acid tetramethylammonium 20 wt% nitrophenol 1 wt% [Example 2] γ-butyrolactone 79 wt% 2,4-dihydroxybenzoic acid Tetramethylammonium 20 wt% Nitrobenzoic acid 1 wt% [Example 3] γ-butyrolactone 74 wt% Tetraethylammonium 2,5-dihydroxybenzoate 25 wt% Nitroacetophenone 1 wt% [Example 4] γ-butyrolactone 69 wt % 2,6-Dihydroxybenzoic acid tetramethylammonium ... 30 wt% Nitroaniline ... 1 wt% [Example 5] gamma-butyrolactone ... 72 wt% 3,4-Dihydroxybenzoic acid tetraethylammonium ... 25 wt% Nitrophenol 3 wt% [Example 6] γ-butyrolactone 87 wt% tetramethylammonium 3,5-dihydroxybenzoate 10 wt% nitrobenzoic acid 3 wt% [Comparative Example 1] γ-butyrolactone 80 wt% tetramethylammonium phthalate 20 wt% [Comparative Example 2] γ-butyrolactone 79 wt% Tetramethylammonium phthalate 20 wt% Nitrobenzoic acid 1 wt% [Comparative Example 3] γ-Butyrolactone 80 wt% Tetramethylammonium maleate 20 wt%. (2) Specific Resistance and Spark Generation Voltage Next, the specific resistance and the spark generation voltage at 25 ° C. of the electrolytic capacitor driving electrolytic solutions of Examples 1 to 6 and Comparative Examples 1 to 3 having the composition shown in (1) were measured. Shown in Table 1 below.

[0018]

[Table 1]

FIG. 1 shows a graph comparing the specific resistance and the spark generation voltage of Examples 1 to 6 and Comparative Examples 1 to 3 described above. As is clear from FIG. 1, in the present invention, tetramethylammonium dihydroxybenzoate or tetraethylammonium dihydroxybenzoate is dissolved in a solvent containing γ-butyrolactone as a main component, and nitrophenol, nitrobenzoic acid, nitroacetophenone, By adding nitrophenol or nitroaniline, the specific resistance is lowered and the spark generation voltage is increased.

(3) High temperature load test Next, 10 initial aluminum electrolytic capacitors (rated 63V-680 μF) manufactured using the electrolytic solution for driving the electrolytic capacitors of Examples 1 to 6 and Comparative Examples 1 to 3 were used. Table 2 below shows the capacitance in stages, and the capacitance change rate after the high temperature load test (1000 hours, 2000 hours) with the rated voltage applied at 105 ° C.

[0021]

[Table 2]

As is clear from Table 2, in Comparative Example 3, the explosion-proof valve was already activated at the initial stage, and it is impossible to use it as a 63V capacitor.

Further, Comparative Examples 1 and 2 have some characteristics at the initial stage, but the deterioration of the characteristics after that is remarkable, and the explosion-proof valve is activated in 1000 hours. It is impossible to use it for business. Compared to these Comparative Examples 1 to 3, in Examples 1 to 6, the decrease in capacitance was 4.3 to 4.5% even after 2000 hours, and the explosion-proof valve was stable and stable. There is.

(4) Effects of the Embodiment The effects of this embodiment as described above are as follows. That is, since the specific resistance can be lowered by making the composition of the electrolytic solution as in the above embodiment, the electrolytic capacitor to which this embodiment is applied can realize a sufficiently low resistance.

Further, since the spark voltage can be increased in the above embodiment, the leakage current and tan δ of the electrolytic capacitor to which this embodiment is applied are small.

Further, the electrolytic capacitor to which this embodiment is applied has a small change with time even at high temperature, can maintain stable high characteristics, and has a long life. Therefore, 50
It can be used for high voltage capacitors exceeding V, and the application range is expanded. In particular, it has been confirmed that Examples 1 and 2 can withstand the use of capacitors up to 100 V class.

Incidentally, the combination and wt% of each compositional substance in the present invention can be appropriately changed. However, the numerical range of wt% suitable for obtaining the effect of the present invention is as follows. That is, the amount of the salt of dihydroxybenzoic acid is preferably 10 wt% to 30 wt%. This is 10
If it is less than wt%, there is no effect in reducing the specific resistance.
When it exceeds, the specific resistance will not drop below that,
This is because the effect is the same as in the case of 10 wt% to 30 wt%.

The amount of nitro compound added is 0.5 w.
t% to 5 wt% is desirable. This is because if it is less than 0.5 wt%, the effect of suppressing generation of hydrogen gas and decomposition of halogenated hydrocarbon cannot be obtained, and if it exceeds 5 wt%, it is 0.5 wt%.
This is because the effect is the same as in the case of 10% to 5% by weight.

[0029]

The electrolytic solution for driving an electrolytic capacitor of the present invention has a constitution in which a tetramethylammonium salt of dihydroxybenzoic acid or a tetraethylammonium salt of dihydroxybenzoic acid is dissolved as a solute in a solvent mainly containing γ-butyrolactone. , An electrolytic capacitor for driving an electrolytic capacitor that has stable characteristics in a wide temperature range, can form a capacitor with long life and high reliability, and can also be used at a higher voltage than before A liquid can be provided.

[Brief description of drawings]

FIG. 1 is a schematic diagram of Embodiments 1 to 6 and Comparative Examples 1 to 3 according to the present invention.
It is a figure which shows the graph which compared the specific resistance and the spark generation voltage with.

Claims (2)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor using a solvent mainly comprising γ-butyrolactone, wherein the solute dissolved in the solvent is tetramethylammonium salt of dihydroxybenzoic acid or tetraethylammonium salt of dihydroxybenzoic acid. An electrolytic solution for driving an electrolytic capacitor, which is mainly composed of an electrolytic solution. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein at least one of nitrophenol, nitrobenzoic acid, nitroaniline and nitroacetophenone is added.