JP4576319B2 - Electrolytic solution for driving electrolytic capacitors - Google Patents

Description

  The present invention relates to an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution), and more particularly to an electrolytic solution with improved leakage current at high temperature and no load.

With the recent miniaturization of electrolytic capacitors, as the anode foil of the electrolytic capacitor, a material having a high etching magnification is used. As a result, an electrolyte solution having a low specific resistance is required.
On the other hand, as an electrolytic solution for medium- and high-pressure aluminum electrolytic capacitors, conventionally, ethylene glycol is used as a main solvent, and organic carboxylic acid or its ammonium salt and boric acid or its ammonium salt are blended to increase the withstand voltage of the electrolytic solution. In order to achieve this, an electrolytic solution to which a polyhydric alcohol such as mannitol or sorbitol is added has been proposed (for example, see Patent Documents 1 to 3).
Japanese Examined Patent Publication No. 7-48459 (page 1-4) Japanese Examined Patent Publication No. 7-48460 (page 1-3) Japanese Examined Patent Publication No. 7-63047 (page 1-4)

  In order to further reduce the specific resistance with the electrolytic solution, it is necessary to increase the concentration of the electrolyte or to mix a large amount of water. However, when the electrolyte concentration is increased, the electrolyte is deposited and the withstand voltage is lowered. When a large amount of water is added, there is a problem that the leakage current of the electrolytic capacitor at high temperature and no load is remarkably increased.

  In view of the above problems, an object of the present invention is to drive an electrolytic capacitor capable of suppressing an increase in leakage current at a high temperature and no load without reducing the withstand voltage even when the specific resistance is reduced. It is to provide an electrolytic solution.

  The present invention has been accomplished as a result of various studies to solve the above-described problems, and intends to apply the characteristics of geranyl formate to an electrolytic solution. That is, the electrolytic solution for driving an electrolytic capacitor according to the present invention is characterized in that at least an organic carboxylic acid or a salt thereof and geranyl formate represented by the following chemical formula are blended in a solvent containing ethylene glycol and water. And

  In this invention, it is preferable that the compounding quantity of geranyl formate is 0.1-1.0 wt% with respect to the whole electrolyte solution.

  In this invention, it is preferable that the compounding quantity of water is 2.0-10.0 wt% with respect to the whole electrolyte solution.

  The geranyl formate used in the electrolytic solution according to the present invention is easily dissolved in a mixed solvent of ethylene glycol and water, and is stable at high temperatures even when water is added to the electrolytic solution to reduce the specific resistance. Excellent in properties. For this reason, the characteristic improvement and reliability improvement of an electrolytic capacitor can be aimed at. Moreover, even if the amount of water is large, an increase in leakage current when the electrolytic capacitor is not loaded at high temperature can be suppressed. Furthermore, since the specific resistance can be reduced by blending water, it is not necessary to increase the electrolyte concentration, so that the withstand voltage is not lowered.

The electrolytic solution according to the present invention is characterized in that at least an organic carboxylic acid or a salt thereof and geranyl formate represented by the above chemical formula are blended in a solvent containing ethylene glycol and water.
Here, it is preferable that the compounding quantity of geranyl formate is 0.1-1.0 wt% with respect to the whole electrolyte solution. The blending amount of water is preferably 2.0 to 10.0 wt% with respect to the entire electrolytic solution. Moreover, you may mix | blend boric acid or its ammonium salt.

  In the present invention, examples of the organic carboxylic acid include azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, and 7-vinylhexadecene-1,16-dicarboxylic acid. Can do.

  In addition to ammonium salts, organic carboxylic acids and boric acid salts include primary amine salts such as methylamine, ethylamine, and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine, and diethylamine, trimethylamine, and diethylamine. Examples thereof include tertiary amine salts such as methylamine, ethyldimethylamine and triethylamine, and quaternary ammonium salts such as tetramethylammonium and triethylmethylammonium.

In the electrolytic solution to which the present invention is applied, geranyl formate is easily dissolved in a mixed solvent of ethylene glycol and water, and is stable under high temperature even when water is added to the electrolytic solution in order to reduce the specific resistance. Excellent in properties. For this reason, the characteristic improvement and reliability improvement of an electrolytic capacitor can be aimed at.
Moreover, even if the amount of water is large, it is possible to suppress an increase in leakage current when the electrolytic capacitor is not loaded at a high temperature. The reason is that geranyl formate is adsorbed on the surface of the electrode foil in the electrolyte solution, so even if the amount of water is increased, the hydration reaction between water and the electrode foil under a high temperature condition of 105 ° C. can be suppressed. It is thought that.
Further, in the present invention, since the specific resistance can be reduced by blending water, it is not necessary to increase the electrolyte concentration, so that the withstand voltage is not lowered.

  Hereinafter, based on an Example, this invention is demonstrated more concretely. An electrolyte solution was prepared with the composition shown in Table 1, and the specific resistance at 30 ° C. was measured.

  Next, using the electrolytic solution shown in Table 1, 10 aluminum electrolytic capacitors each having a rating of 400V-22 μF (φ16 × 25 mmL) were prepared, and after initial characteristics measurement for tan δ and leakage current, a high temperature no load test (105 The result shown in Table 2 was obtained.

  With reference to Tables 1 and 2, Examples 1 to 15 using ammonium 1,6-decanedicarboxylate as the organic carboxylate will be described first.

  In Table 2, examples in which geranyl formate was blended, as can be seen by comparing the same amount of water, for example, Conventional Example 2 in which the amount of water is 5 wt%, and Examples 2, 3, 5, and 7, 2, 3, 5, and 7 show an excellent characteristic in which an increase in leakage current is suppressed in a high-temperature no-load test.

  However, when the blending amount of geranyl formate is 0.05 wt% with respect to the entire electrolyte solution, the effect of suppressing leakage current is not sufficient (Example 1), and the blending amount of geranyl formate is based on the entire electrolyte solution. When the content exceeds 1.0 wt%, the specific resistance increase increases (Example 9), which indicates that it is not suitable for low specific resistance applications. Therefore, the blending amount of geranyl formate is preferably in the range of 0.1 to 1.0 wt% with respect to the entire electrolyte solution.

  Further, when the amount of water blended is less than 2.0 wt% with respect to the entire electrolyte, the specific resistance is high (Examples 10 to 11), and when the amount of water exceeds 10.0 wt% with respect to the entire electrolyte, formic acid There is a tendency for the effects of geranyl to decrease (Example 15). Therefore, the blending amount of water is preferably 2.0 to 10.0 wt% with respect to the entire electrolytic solution.

  In addition, when ammonium sebacate was used as the organic carboxylic acid (Example 16) and when ammonium azelate was used (Example 17), the effect of suppressing increase in leakage current due to geranyl formate was also observed as described above. It was.

In addition, the effect of incorporating geranyl formate was not limited to the above-mentioned examples, and the same effect was obtained even when used in an electrolyte containing one or more of the organic carboxylic acids and salts thereof described above. .

Claims (3)

An electrolytic solution for driving an electrolytic capacitor, wherein at least an organic carboxylic acid or a salt thereof and geranyl formate represented by the following chemical formula are blended in a solvent containing ethylene glycol and water.

  The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the amount of geranyl formate is 0.1 to 1.0 wt% with respect to the entire electrolytic solution. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the amount of water is 2.0 to 10.0 wt% with respect to the entire electrolytic solution.