JP2006351912A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte capable of suppressing the increase of the leaking current of an electrolytic capacitor in the case of it at a high temperature and an unloaded condition, even when lowering the resistivity of the electrolyte by adding a water thereto. <P>SOLUTION: In the electrolyte, there are mixed with the solvent wherein an ethylene glycol and a water are blended, organic carboxylic acids comprising an adipic acid, an azelaic acid, a sebacic acid, a 1,6-decane dicarboxylic acid, and the like or the salts thereof, and a 1,4-dioxane-2,3-diol represented by a chemical formula I. The blending quantity of the 1,4-dioxane-2,3-diol is, for example, 0.1-10.0 wt.%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of 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.

Along with the recent miniaturization of aluminum electrolytic capacitors, the anode foil of aluminum electrolytic capacitors has come to be used with a high etching magnification, and an electrolytic solution having a low specific resistance is required. Conventionally, electrolytes of medium- and high-pressure aluminum electrolytic capacitors contain ethylene glycol as the main solvent, organic carboxylic acid, boric acid or its ammonium salt, etc., and mannitol to increase the withstand voltage of the electrolyte. In addition, an electrolytic solution to which a polyhydric alcohol such as sorbitol is added has been proposed (see, for example, Patent Documents 1 to 3).
Japanese Examined Patent Publication No. 7-48459 (page 1-4) Japanese Patent Publication No. 7-48460 (page 1-3) Japanese Examined Patent Publication No. 7-63047 (page 1-4)

  However, in order to obtain an electrolyte with low specific resistance, the concentration of the electrolyte must be increased or a large amount of water must be mixed. However, when the electrolyte concentration is increased, electrolyte deposition and withstand voltage decrease occur, When a large amount of water is mixed, the leakage current increases remarkably when the aluminum electrolytic capacitor is left unloaded at high temperature. For this reason, it is the present condition that the electrolytic solution has a low specific resistance and an aluminum electrolytic capacitor with a small increase in leakage current at high temperature and no load cannot be realized.

  In view of the above problems, an object of the present invention is to provide an electrolytic solution capable of suppressing an increase in leakage current at high temperature and no load even when water is added to reduce the specific resistance.

  The present invention has been discovered as a result of various studies in order to solve the above-mentioned problems, and focuses on 1,4-dioxane-2,3-diol and attempts to apply the characteristics to an electrolytic solution.

  That is, in the electrolytic solution for driving an aluminum electrolytic capacitor according to the present invention, at least an organic carboxylic acid or a salt thereof and 1,4-reaction represented by the following chemical formula with respect to a mixed solvent containing at least ethylene glycol and water. Dioxane-2,3-diol is blended.

  In this invention, it is preferable that the compounding quantity of 1, 4- dioxane-2, 3-diol is 0.1-10.0 wt% with respect to the whole electrolyte solution.

  In this invention, it is preferable that the compounding quantity of water is 2.0-70.0 wt% with respect to the whole electrolyte solution.

In the present invention, the organic carboxylic acid includes polycarboxylic acids azelaic acid, 2-methyl azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, 7-vinylhexadecene- Examples thereof include 1,16-dicarboxylic acid.
In addition, when the rated voltage of the aluminum electrolytic capacitor, that is, at low or medium pressure, the organic carboxylic acid is oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, maleic acid, fumaric acid. Acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, thiodipropionic acid, etc., as oxycarboxylic acid, glycolic acid, lactic acid, tartaric acid, salicylic acid, mandelic acid, etc. Monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid, acrylic acid, methacrylic acid, Oleic acid, benzoic acid, p-nitrobenzoic acid, anisic acid, cumic acid, cinnamic acid, Etc. may be used Futoe acid.
Further, borodisoxalic acid, borodiglycolic acid, borodisalicylic acid, ethylene glycol borate ester and the like may be used in combination.

  In addition to ammonium salts, organic carboxylic acid salts include primary amine salts such as methylamine, ethylamine, and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine, and diethylamine, trimethylamine, diethylmethylamine, Examples thereof include tertiary amine salts such as ethyldimethylamine, triethylamine and N, N-dimethyl-N- (2-methoxyethyl) amine, and quaternary ammonium salts such as tetramethylammonium and triethylmethylammonium.

  Furthermore, various additives can be added to the electrolytic solution according to the present invention for the purpose of reducing leakage current, improving withstand voltage, and absorbing gas. Examples of additives include phosphoric acid compounds, boric acid compounds, polyhydric alcohols, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycol random copolymers and block copolymers. A molecular compound, a nitro compound, etc. are mentioned.

Since 1,4-dioxane-2,3-diol is blended in the electrolytic solution according to the present invention, even when low resistivity is achieved using a solvent containing water, leakage at high temperature and no load is achieved. An increase in current can be suppressed, and the reliability of the aluminum electrolytic capacitor can be improved.
Further, even when the specific resistance is reduced, the withstand voltage is high because it is not necessary to increase the electrolyte concentration.
Furthermore, since 1,4-dioxane-2,3-diol is easily dissolved in a mixed solvent of ethylene glycol and water, there is no problem such as precipitation.

In the electrolytic solution for driving an aluminum electrolytic capacitor according to the present invention, at least an organic carboxylic acid or a salt thereof and 1,4-dioxane-2,3-diol with respect to a mixed solvent containing at least ethylene glycol and water. Is blended.
For this reason, even when the specific resistance is reduced using a solvent containing water, an increase in leakage current at high temperature and no load can be suppressed, and the reliability of the aluminum electrolytic capacitor can be improved.
The reason is that 1,4-dioxane-2,3-diol is adsorbed on the surface of the electrode foil to protect the electrode foil. Therefore, even when the amount of water is high, water and the electrode foil at a high temperature of 105 ° C. This is considered to suppress the hydration reaction.

  Hereinafter, based on an Example, this invention is demonstrated more concretely. First, after preparing electrolyte solution with the composition shown in Table 1, the specific resistance in 30 degreeC was measured. The results are shown in Table 1.

  First, as the conventional examples 1 to 3 and examples 1 to 14, using the electrolytic solution shown in Table 1, ten aluminum electrolytic capacitors each having a rating of 400V-22 μF (φ16 × 25 mmL) were produced, and tan δ, leakage current After measuring initial characteristics, a high temperature no-load test (left at 105 ° C. for 1000 hours) was performed, and tan δ and leakage current after the test were measured. The results are shown in Table 2.

  In addition, using the electrolytic solution shown in Table 1, 10 aluminum electrolytic capacitors each having a rating of 6.3 V-1500 μF (φ10 × 12.5 mmL) were produced as Conventional Example 4 and Examples 15 to 18, and tan δ, After measuring initial characteristics of the leakage current, a high temperature no-load test (left at 105 ° C. for 1000 hours) was performed, and tan δ and leakage current after the test were measured. The results are shown in Table 3.

  As is apparent from Table 2, the aluminum electrolytic capacitors using the electrolyte solutions according to Examples 1 to 12 of the present invention are not loaded with high temperature, although water is added to reduce the specific resistance of the electrolyte solution. The increase in leakage current in the test is small. More specifically, when the water content is the same, for example, when Conventional Example 2 having a water content of 5 wt% is compared with Examples 2, 3, 5, 7, and 9, 1,4-dioxane-2, The aluminum electrolytic capacitor using the electrolyte solution according to Examples 2, 3, 5, 7, and 9 blended with 3-diol is superior in that the increase in leakage current is suppressed in the high temperature load test and the high temperature no load test. Shows the characteristics.

  However, when the blending amount of 1,4-dioxane-2,3-diol is less than 0.1 wt% (Example 1), the effect of suppressing an increase in leakage current is not sufficient, and the blending amount is 10.0 wt. If the ratio exceeds 50% (Example 4), the specific resistance increases, and is not suitable for low specific resistance applications. Therefore, the blending amount of 1,4-dioxane-2,3-diol is preferably in the range of 0.1 to 10.0 wt%. In addition, when the moisture content is less than 2.0 wt% (Example 11), the specific resistance is high.

  Moreover, such an effect is the same even when ammonium sebacate is used as the organic carboxylic acid (Example 13) or when ammonium azelaate is used (Example 14).

  As is apparent from Table 3, the aluminum electrolytic capacitors using the electrolytic solutions according to Examples 15 to 17 of the present invention were not loaded with high temperature, although water was added to reduce the specific resistance of the electrolytic solution. The increase in leakage current in the test is small. However, when the moisture content is 70.0 wt% or less (Examples 15 to 16), the effect of suppressing an increase in leakage current is significant, but when the moisture content is 75.0 wt% (Example 17), Leakage current tends to increase. Therefore, the blending amount of water is preferably 2.0 to 70.0 wt%.

  In addition, the effect | action which mix | blended 1,4-dioxane-2,3-diol is not limited to the said Example, It uses for the electrolyte solution which mix | blended the organic carboxylic acid or its salt described previously individually or in multiple numbers. But it had the same effect.

Claims (3)

The mixed solvent containing at least ethylene glycol and water contains at least an organic carboxylic acid or a salt thereof and 1,4-dioxane-2,3-diol represented by the following chemical formula. Electrolytic solution for driving electrolytic capacitors.

  An electrolytic solution for driving an electrolytic capacitor, wherein the amount of 1,4-dioxane-2,3-diol according to claim 1 is 0.1 to 10.0 wt% with respect to the entire electrolytic solution.   3. The electrolytic solution for driving an electrolytic capacitor, wherein the amount of water according to claim 1 or 2 is 2.0 to 70.0 wt% with respect to the entire electrolytic solution.