JP2007115947A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte for driving an electrolytic capacitor which can obtain high reliability by suppressing the hydration reaction of an aluminum electrode foil, even if water is added to realize low specific resistance. <P>SOLUTION: In the electrolyte for driving an electrolytic capacitor, an acid such as an organic calboxylic acid or its salt and guanylurea phosphate are blended in a solvent in which 30-80 wt.% water is mixed into an organic solvent such as ethylene glycol. The amount of blending of the guanylurea phosphate is preferably 0.1-3.0 wt.%. The guanylurea phosphate suppresses deterioration of a dielectric coating of the surface of an electrode foil due to humidity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution).

In order to manufacture an aluminum electrolytic capacitor, a high-purity aluminum foil is electrochemically etched to increase the surface area, and then subjected to a chemical conversion treatment in a chemical conversion solution such as an ammonium borate aqueous solution or an ammonium adipate aqueous solution. An oxide film is formed on the etching foil surface to obtain an anode foil. Also, the aluminum foil is etched to obtain a cathode foil, a separator is inserted between the cathode foil and the anode foil and wound to produce a capacitor element.
Such a capacitor element is impregnated with an electrolytic solution and then accommodated in a metal cylindrical case. Moreover, the opening part of a cylindrical case is sealed by elastic rubber, and it seals by drawing-processing the sealed site | part.

In recent years, with the progress of digitalization of electronic components, there is an increasing demand for low loss and low impedance of electrolytic capacitors, and the electrolyte used for electrolytic capacitors is aimed at high conductivity (low specific resistance). Development is underway.
Conventionally, low pressure electrolytes have been made of ethylene glycol as the main solvent and ammonium salts such as adipic acid and benzoic acid as solutes. Recently, however, the amount of water in the electrolyte has been increased for electrolysis. A method for reducing the specific resistance of the liquid has been proposed (see, for example, Patent Documents 1 and 2).
Japanese Patent No. 3366267 (page 1-10) Japanese Patent No. 3366268 (page 1-21)

  However, when the blending amount of water in the electrolytic solution is increased, the water in the electrolytic solution and the aluminum electrode foil cause a hydration reaction, so that the electrical characteristics and life of the electrolytic capacitor are significantly reduced. Since such a hydration reaction becomes conspicuous with an increase in the amount of water in the electrolytic solution, if the amount of water is increased to reduce the specific resistance of the electrolytic solution, the reliability is sufficiently maintained. There is a problem that can not be.

  In view of the above problems, an object of the present invention is to provide an electrolytic solution that can obtain high reliability by suppressing the hydration reaction of the aluminum electrode foil even when water is mixed to reduce the specific resistance. Is to provide.

  The present invention is an invention that has been achieved as a result of various studies in order to solve the above-described problems, and intends to use guanylurea phosphate as an electrolyte. That is, the electrolytic solution for driving an electrolytic capacitor according to the present invention is characterized in that at least a carboxylic acid or a salt thereof and guanylurea phosphate are blended in a solvent in which an organic solvent and water are blended.

  The present invention can be applied to an electrolytic solution in which the amount of water is 20 to 80 wt% with respect to the entire electrolytic solution.

  In this invention, it is preferable that the compounding quantity of guanyl urea phosphate is 0.1 to 3.0 wt% with respect to the whole electrolyte solution.

  In the present invention, the carboxylic acid is, for example, formic acid, acetic acid, propionic acid, benzoic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, phthalic acid, azelaic acid, citric acid, and boric acid. , At least one.

  In the present invention, the electrolytic solution further comprises orthophosphoric acid, phosphorous acid, hypophosphorous acid, monomethyl phosphate, dimethyl phosphate, monoethyl phosphate, diethyl phosphate, monopropyl phosphate, dipropyl phosphate, monophosphate. It is preferable to include at least one of ethylene glycol and diethylene glycol phosphate.

  In addition, various additives generally used as an electrolyte for driving a capacitor can be added to the electrolyte according to the present invention for the purpose of reducing leakage current, improving withstand voltage, gas absorption, and the like. Examples of additives include sugars such as glucose, fructose, mannitol, xylose, galactose, polymer compounds such as polyvinyl alcohol, polyethylene glycol, polypropylene glycol, nitro compounds such as nitrophenol, nitroacetophenone, nitroanisole, dinitrobenzoic acid, etc. Is mentioned.

When phosphoric acids are added to the electrolytic solution, there is an effect of suppressing the hydration reaction between the electrode foil and water. In the present invention, guanyl urea phosphate is blended as phosphoric acids.
Since this guanylurea phosphate has a high effect of suppressing the hydration reaction between the aluminum electrode foil and water, the aluminum electrode foil can be reliably prevented from being deteriorated by moisture.
Therefore, it is possible to suppress deterioration of electrical characteristics and lifetime of the electrolytic capacitor and improve reliability.

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

  Next, 10 electrolytic capacitors each having a rating of 6.3 V-1500 μF (φ10 × 12.5 mmL) were prepared using the electrolyte shown in Table 1, and after initial characteristics measurement of tan δ and leakage current, high temperature load test (Applied at 105 ° C. and a rated voltage of 3000 hours) and the results shown in Table 2 were obtained.

  In Table 2, when the blending amounts of water are equal, that is, when Comparative Example 2 having a water content of 50 wt% and Examples 3 to 6 are compared, when guanylurea phosphate is added, tan δ and leakage current are measured in a high-temperature load test. Increase and valve expansion are suppressed, showing excellent characteristics.

  Here, when the blending amount of guanylurea phosphate is less than 0.1 wt% (Examples 1 and 2) or more than 3.0 wt% (Example 7) with respect to the whole electrolyte solution, valve expansion is suppressed. The effect is not enough. Therefore, the blending amount of guanylurea phosphate is preferably in the range of 0.1 to 3.0 wt%. In addition, the specific amount of moisture is less than 20 wt% with respect to the total electrolyte solution (Example 10), and when the amount exceeds 80 wt%, the specific resistance is reduced, but guanyl urea phosphate is realized. It can be seen that the effect of is reduced (Example 11). Therefore, the blending amount of moisture is preferably 20 to 80 wt%.

In addition to the above examples, formic acid, acetic acid, propionic acid, benzoic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, phthalic acid, azelaic acid, citric acid, boric acid, or salts thereof Even with the electrolytes mixed at different concentrations, guanylurea phosphate was able to suppress the deterioration of electrical characteristics and the life reduction.
In addition, phosphoric acid, hypophosphorous acid, monomethyl phosphate, dimethyl phosphate, monoethyl phosphate, diethyl phosphate, monopropyl phosphate, dipropyl phosphate, phosphoric acid as other phosphoric acids for the electrolyte Even when monoethylene glycol and diethylene glycol phosphate were blended, an effect of suppressing tan δ, increase in leakage current and valve expansion in a high temperature load test was obtained by combining with guanyl urea phosphate.

  In addition, this invention is not limited to the said Example, The general additive used for the electrolyte solution which melt | dissolved the various solutes illustrated previously individually or more than one, and also for the electrolytic solution for driving an electrolytic capacitor The electrolyte solution to which was added also had the same effect as the above example.

Claims (5)

  An electrolytic solution for driving an electrolytic capacitor, wherein at least a carboxylic acid or a salt thereof and guanylurea phosphate are blended in a solvent in which an organic solvent and water are blended.   2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the amount of water is 20 to 80 wt% with respect to the entire electrolytic solution.   2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the blending amount of guanylurea phosphate is 0.1 to 3.0 wt% with respect to the entire electrolytic solution.   The carboxylic acid according to claim 1, wherein the carboxylic acid is at least one of formic acid, acetic acid, propionic acid, benzoic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, phthalic acid, azelaic acid, citric acid, and boric acid. An electrolytic solution for driving an electrolytic capacitor, which is one type.   5. The method according to claim 1, further comprising orthophosphoric acid, phosphorous acid, hypophosphorous acid, monomethyl phosphate, dimethyl phosphate, monoethyl phosphate, diethyl phosphate, monopropyl phosphate, dipropyl phosphate, phosphorus An electrolytic solution for driving an electrolytic capacitor comprising at least one of acid monoethylene glycol and diethylene glycol phosphate.