JPH02185012A - Electrolytic solution for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To maintain the stable characteristics for a long period of time by using a practically nonaqueous high-conductivity electrolytic solution having an aprotic solvent as its main substance. CONSTITUTION:This electrolytic solution for electrolytic capacitors contains mono-or ditetraalkylarsonium compound salt being a phenyl carboxylic acid compound shown by formula (I), as an electrolyte, in a solvent having an aprotic solvent as its main substance. In the formula (I), R1-R4 express alkyl groups with 1-6 carbon atom(s) being the same as or different from each other, and X1-X3 express hydrogen atoms, lower alkyl groups, hydroxy groups, lower alcoxy groups, nitro groups, carboxyl groups, or groups chosen from of arbitrary one out of the above-mentioned carboxyl groups and a tetraalkylarsonium compound group shown in the formula (I). And, this makes it possible to maintain the stable characteristics for a long time even under a wide range of temperature environments.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrolytic solution used in an electrolytic capacitor, and particularly to an electrolytic solution containing an aprotic solvent as a main solvent.

[Conventional technology]

Electrolytic capacitors use a valve metal such as aluminum or tantalum on the surface of which an insulating oxide film is formed, and use the oxide film layer as a dielectric, and an electrolyte layer on the surface of the oxide film layer. by contacting an electrolytic solution of
Furthermore, a current collecting electrode, usually called a cathode, is arranged.

As described above, the electrolyte for an electrolytic capacitor comes into direct contact with the dielectric and acts as a true cathode. That is, the electrolytic solution is interposed between the dielectric layer and the current collecting cathode of the electrolytic capacitor, and the resistance bones of the electrolytic solution are inserted in series with the electrolytic capacitor.

Therefore, the characteristics of the electrolyte are a major factor that influences the characteristics of electrolytic capacitors. For example, if the conductivity of the electrolytic solution is low, the equivalent series resistance inside the electrolytic capacitor increases, resulting in poor high frequency characteristics and loss characteristics.

Conventionally, organic acids such as adipic acid or their salts dissolved in glycols such as ethylene glycol or alcohols have been used as electrolytes with high conductivity in order to improve high frequency characteristics, loss characteristics, etc. There is.

[Problem to be solved by the invention]

However, as the range of use of electronic devices has increased in recent years, there has been a growing demand for improvements in the performance of electrolytic capacitors, and the current conductivity of electrolytes is no longer sufficient. Especially in the case of current electrolytes, when the desired conductivity cannot be obtained or when an electrolyte with low solubility is used, water is intentionally added to improve the conductivity. .

However, in recent years, electrolytic capacitors are required to be used for long periods of time in a wider temperature environment than conventional products, and the presence of moisture in the electrolyte can cause deterioration of the dielectric film layer and abnormalities in the internal vapor pressure of the electrolytic capacitor. As a result, it becomes difficult to maintain stable characteristics over a long period of time, leading to a decrease in life due to rising, damage to the sealing body, and evaporation of the electrolyte.

An object of the present invention is to improve the electrical characteristics of electrolytic capacitors and maintain stable characteristics for a long period of time by providing a substantially non-aqueous high conductivity electrolytic solution containing an aprotic solvent as a main component. There is a particular thing.

[Means to solve the problem]

This invention provides an electrolytic solution for an electrolytic capacitor in which a solvent of the general formula: an alkyl group, X.

and It is characterized by containing a mono- or di-tetraalkyl arsonium compound salt of a phenylcarboxylic acid compound (representing a group) as an electrolyte.

In addition, the aprotic solvent used is (1)
Amides include tomethylformamide, N,N-dimethylformamide, tomethylformamide, N,N-diethylformamide, N-methylacetamide, N,
N-dimethylacetamide, N-ethylacetamide,
N,N-diethylacetamide, hexamethylphosphoric amide, (2) dimethyl sulfoxide as an oxide system, (3)
Acetonitrile as a nitrile type, (4) cyclic ester, T-butyrolactone, N-methyl- as an amide type.
Representative examples include 2-pyrrolidone, ethylene carbonate, and propylene carbonate.

Further, the polyhydric alcohol compound which is the object of the present invention is preferably a dihydric alcohol compound or a monoalkyl ether of a dihydric alcohol compound, and the dihydric alcohol compound is ethylene glycol, and the dihydric alcohol monoalkyl ether compound is preferably a dihydric alcohol compound or a monoalkyl ether of a dihydric alcohol compound. Methyl cellosolve or ethyl cellosolve.

The weight ratio of the polyhydric alcohol compound to the aprotic solvent is (100-50): (0-50),
An aprotic solvent of 100x is suitable, but up to about 50x of polyhydric alcohol compound may be used as appropriate without substantial product deterioration.

Specific phenylcarboxylic acid compounds include benzoic acid, toluic acid, ethylbenzoic acid, cumic acid, hemeritic acid, mesitylic acid, zurilic acid, phthalic acid, isophthalic acid, terephthalic acid, 5-methylisophthalic acid, and hemimelitic acid. , trimellidic acid, trimesic acid, prenidic acid, merofanic acid, pyromellitic acid, nitrobenzoic acid, dinitrobenzoic acid, 2.4.6-) dinitrobenzoic acid, nitrophthalic acid, nitroisophthalic acid, nitroterephthalic acid,
Hydroxybenzoic acid, salicylic acid, 3-nitrosalicylic acid, 3.5-dinitrosalicylic acid, 2.4-dihydroxybenzoic acid, gentisic acid, γ-resorcylic acid, protocatechuic acid, α-resorcylic acid, gallic acid, 2.3.4 −
) Dihydroxybenzoic acid, 2.4.6-drihydroxybenzoic acid, 6-methylsalicylic acid, 3-methylsalicylic acid, thymotic acid, orceric acid, hydroxyisophthalic acid, hydroxyterephthalic acid, norhemibic acid, anisic acid, vanillic acid, isovanillin acids, veratrum acid, trimethoxybenzoic acid, hemipic acid, etc.

Furthermore, typical specific examples of the tetraalkylarsonium compounds include tetramethylarsonium, triethylmethylarsonium, trimethylethylarsonium, diethyldimethylarsonium, tetraethylarsonium, trimethylisopropylarsonium, and tetrapropylarsonium. , tetrabutyl arsonium, tetrapentyl arsonium and the like.

The tetraalkyl arsonium compound used in the present invention can be prepared by, for example, reacting arsenic trichloride with dimethylzinc.
Synthesize trimethylarsine and alkylate it with an alkyl halide using a conventional method to obtain the corresponding halide 1.
A -alkyltrimethylarsonium compound salt is obtained, which is subjected to electrodialysis using an ion exchange membrane, followed by dehalogenation and desalting for anion exchange to obtain an aqueous solution of a 1-alkyltrimethylarsonium hydroxide compound. To the obtained aqueous solution of the 1-alkyltrimethylarsonium hydroxide compound, equimolar or 1/2 mole of the desired phenylcarboxylic acid compound is added, a neutralization reaction is carried out, and the phenylcarboxylic acid compound is evaporated and solidified under reduced pressure. Mono- or di-1-alkyltrimethylarsonium compound salts of the compounds can be obtained.

The electrolytic solution for an electrolytic capacitor according to the present invention is prepared by adding a mono- or di-1-alkyl of a desired phenylcarboxylic acid compound to a solvent prepared by mixing an aprotic solvent with a polyhydric alcohol compound or its monoalkyl ether compound as required. Obtained by adding and dissolving trimethylarsonium compound salt.

〔Example〕

Table 1 below shows the conductivities of various aprotic solvents of mono- or di-tetraalkyl arsonium compound salts of phenylcarboxylic acid compounds or solutions of these and polyhydric alcohols for examples of electrolytic solutions for electrolytic capacitors according to the present invention. show. Note that a standard electrolytic solution is shown as a conventional example.

As can be seen from the above results, the electrolytic solution of the present invention exhibits higher conductivity than the conventional electrolytic solution.

Next, ten electrolytic capacitors were manufactured using the electrolytes of Examples 1-10 and Comparative Example, and their characteristics were compared.

The manufactured electrolytic capacitors were made by using aluminum foil as an anode and a cathode, and rolling the foil overlappingly with separator paper in between to form a cylindrical capacitor element, which was impregnated with the electrolyte of each example and comparative example. It is stored in an external case and sealed.

Both use the same capacitor element, and have a rated voltage of 16 V and a rated capacity of 180 μF.

Table 2 shows the initial values of these electrolytic capacitors and 110
Capacitance value after 1000 hours after applying rated voltage at °C (CAP: u F), tangent of loss angle (tan δ),
and represents the leakage current (LC:μ^) based on a bipartite value.

As is clear from the results of this test, the electrolytic solution of the present invention has a high conductivity, so the loss, that is, the tan δ value, is lower than that of the conventional electrolytic solution.

In addition, since it essentially does not contain water, its characteristics change little even in low-temperature environments, and it is understood that appearance abnormalities and capacitance decrease rates due to increased internal pressure under high-temperature load conditions are extremely small. be done.

〔Effect of the invention〕

The electrolytic capacitor using the electrolyte according to the present invention has a low loss value and can maintain stable characteristics for a long time even in a wide range of temperature environments, so it can be used at high frequencies and requires high efficiency. It can be used in power supplies such as switching regulators, and various electrical devices that are used at high temperatures for long periods of time.

Claims (1)

[Claims] (1) In a solvent mainly consisting of an aprotic solvent, the general formula:
▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, R_3, R_4 are alkyl groups with 1 to 6 carbon atoms, each of which may be the same or different, X_
1, Represents a selected group. ) An electrolytic solution for electrolytic capacitors containing a mono- or di-tetraalkyl arsonium compound salt of a phenylcarboxylic acid compound as an electrolyte.