JPS61187220A - Electrolytic liquid for electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolytic solution for electrolytic capacitors.According to the present invention, an excellent electrolytic solution for electrolytic capacitors (hereinafter referred to as (also simply referred to as an electrolyte) is obtained.

BACKGROUND ART It is well known that an electrolytic solution for electrolytic capacitors is made by dissolving boric acid, adipic acid, or a salt thereof as a solute in an ethylene glycol solvent. Due to its relatively high freezing point, the specific resistance of the electrolyte increases significantly at low temperatures, and the low-temperature characteristics of electrolytic capacitors are poor.

In order to improve this drawback, it is known to use N,N-dimethylformamide (see Japanese Patent Publication No. 33-3984) or γ-butyrolactone, which has a lower freezing point than ethylene glycol, as the solvent.

However, these solvents have low solubility of ionogens such as boric acid, adipic acid, or their ammonium salts, and cannot reduce the specific resistance of the electrolytic solution.

Summary of the Invention In order to find a new electrolyte solution that solves the above-mentioned problems, the present inventors conducted extensive studies on electrolytes that are combinations of various solvents and solutes, and completed the present invention.

That is, the present invention provides an electrolytic solution for an electrolytic capacitor characterized by dissolving ditriethylammonium pyromellitate in a solvent mainly containing γ-butyrolactone.

Effects of the Invention The electrolytic solution for electrolytic capacitors of the present invention exhibits extremely low specific resistance over a wide temperature range, and can be used in a wide temperature range.

Detailed Description of the Invention The electrolytic solution of the present invention is used by dissolving ditriethylammonium pyromellitate as a solute in a γ-butyrolactone solvent. In this case, the concentration of the solute is 1 to 30% by weight, preferably 5 to 30% by weight. It is used in a range of 20% by weight.

Ditriethylammonium pyromellitate can be obtained by neutralizing pyromellitic acid with triethylamine slightly in excess of 2 equivalents, but the electrolytic solution of the present invention is obtained by adding pyromellitic acid and 2 equivalents of triethylamine to a solvent and dissolving them by heating. It can also be prepared by

The electrolytic solution of the present invention essentially consists of the above-mentioned γ-butyrolactone and ditriethylammonium pyromellitate, but for the purpose of preventing galvanic corrosion, reducing leakage current, absorbing hydrogen gas, etc. Co-solutes such as phosphoric acid or phosphoric acid-derived K such as its ammonium salt or amine salt, dinitrobenzene, dinitrophenol, nitrobenzene derivatives such as picric acid, etc. can be added. Furthermore, the resistivity of the electrolytic solution can be further reduced by adding a small amount of water, for example 1 to 5% by weight, to the electrolytic solution of the present invention within a range that does not adversely affect the temperature characteristics.

EXPERIMENTAL EXAMPLES The present invention will be explained in more detail with reference to Examples and Comparative Examples below. The ditriethylammonium pyromellitate used in the following Experimental Examples was prepared by adding triethylamine in a slight excess of 2 equivalents of pyromellitic acid. It was obtained by neutralizing and then heating and drying under reduced pressure.

Example 1 An electrolytic solution was prepared by dissolving 10% by weight of ditriethylammonium pyromellitate in a γ-butyrolactone solvent.

Conductive dust of this electrolyte at 25°C (using a conductivity needle "CM-6A" manufactured by Toa Denpa Kogyo Co., Ltd.) and a constant current of 5 mA/eta applied to a pair of + and - aluminum smooth foils. The spark generation voltage was measured. Conductive dust is 2.
14 ms/crn, and the spark generation voltage was 125V.

Example 2 An electrolytic solution was prepared by adding 10% by weight of ditriethylammonium pyromellitate and 5% by weight of water to an r-butyrolactone solvent. The conductive dust of this electrolyte is 4.70
m8/cm, and the spark generation voltage was 125V.

Comparative Example 1 In Example 1, an attempt was made to prepare an electrolytic solution by using ditrimethylammonium pyromellitate instead of ditriethylammonium pyromellitate, but some of it did not dissolve and was unsuitable for use as an electrolytic solution. Ta.

Comparative Example 2 In Example 1, an attempt was made to prepare an electrolytic solution using didiethylammonium pyromellitate instead of ditriethylammonium pyromellitate, but some of it did not dissolve and was unsuitable for use as an electrolytic solution. Ta.

Comparative Example 3 An attempt was made to prepare an electrolytic solution by adding pyromellitic acid and triethylamine to a γ-butyrolactone solvent such that the molar ratio of triethylamine to pyromellitic acid was 1 and the amount of solute was 10% by weight. Part of the solute was not dissolved, making it unsuitable for use as an electrolyte.

Comparison Row 4 In Comparative Example 3, an electrolytic solution with a molar ratio of triethylamine to pyromellitic acid of 3 was prepared, and the amount of conductive dust was 1.50 m5/cW1.

Comparative Example 5 In Comparative Example 3, an electrolytic solution with a molar ratio of triethylamine to pyromellitic acid of 4 was prepared, and the conductive dust was 1.28 mS/m.

Patent Applicant Mitsubishi Yuka Co., Ltd. Agent Patent Attorney Hidetoshi Furukawa Agent Patent Attorney Masahisa Hase Procedural Amendment (Voluntary) 1985! Month 9th l Display of case 1985 Patent Application No. Core 4I7a No. 3
Title of the invention Electrolyte solution for electrolytic capacitors Relationship to the case of the person making the amendment Patent applicant address 2-3 Marunouchi, Chiyoda-ku, Tokyo Name (1)
, 0 Mitsubishi Yuka Co., Ltd. Hiro Agent Address: 2-chome, Marunouchi, Chiyoda-ku, Tokyo No. J Column for detailed description of the invention in the specification Contents of the amendment

Claims (1)

[Claims] (1) An electrolytic solution for an electrolytic capacitor, characterized in that ditriethylammonium pyromellitate is dissolved in a solvent mainly containing γ-butyrolactone.