JPH0269915A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve the electric characteristics and reliability of an electrolytic capacitor by incorporating specific compound salt in a predetermined solvent as electrolyte. CONSTITUTION:When a mono- or di-N-alkyl-1-azabicyclo[m,n,p]arcanium compound salt of compound phenylcarboxylate represented by a formula I is contained in a solvent containing as a main gradient nonproton solvent as electrolyte, it becomes an electrolyte containing the nonproton solvent as a main ingredient and having substantially nonaqueous high conductivity. Accordingly, when this electrolyte is used, its characteristics are stabilized even at the time of use for a long period of time at a high temperature with low loss to enhance its electric characteristics to obtain an electrolytic capacitor having stable characteristics to be maintained for a long period of time with high reliability. In the formula, m, n: 2 or 3, p: 1, 2 or 3, R2: 6-0C alkyl group, X1-X3: hydrogen atom, or a group selected from the salt of the same group as the ammonium group in the formula I of lower alkyl group, hydroxy group, lower alkoxy group, nitro group, carboxylic group or carboxyl group.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an electrolytic capacitor for electrolytic capacitors containing an ethylkyl-1 azabicycloalkanium compound salt of a phenylcarboxylic acid compound as an electrolyte in a solvent mainly consisting of an aprotic solvent. It is related to liquid.

(Prior art) An electrolytic capacitor uses a valve metal such as aluminum or tantalum on the surface of which an insulating oxide film is formed as an anode electrode, the oxide film layer is used as a dielectric, and the surface of the oxide film layer is It is constructed by bringing an electrolytic solution, which forms an electrolyte layer, into contact with it, and further arranging a current collecting electrode, usually called a cathode.

As described above, the electrolytic solution for an electrolytic capacitor comes into direct contact with the dielectric layer 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 of the electrolytic solution is inserted in series with the electrolytic capacitor. Therefore, its characteristics are a major factor that influences the characteristics of electrolytic condensers. For example, if the electrolytic solution has a low amount of conductive dust, it increases the equivalent series resistance inside the electrolytic capacitor, resulting in poor high frequency characteristics and loss characteristics.

Against this background, there is a demand for electrolytes with high conductive dust, and conventionally known electrolytes with high conductive dust include organic acids such as ampic acid or their salts dissolved in glycols such as ethylene glycol or alcohols. These are mainly used for normal purposes.

(Problems to be Solved by the Invention) Due to the recent increase in the scope of use of electronic devices, there has been an increasing demand for improvements in the performance of electrolytic capacitors, and the current conductive dust in electrolytes is not sufficient. Especially in the case of current electrolytes, when the desired conductive dust cannot be obtained or when an electrolyte with low solubility is used, water is intentionally added to improve the conductive dust. .

However, in recent years, when electrolytic capacitors are used for long periods of time at higher temperatures than conventional products, the presence of moisture in the electrolyte can cause deterioration of the dielectric film layer and internal steam of the electrolytic capacitor. This increases the pressure, leading to damage to the sealing part and evaporation of the electrolyte, which shortens its lifespan, and has the disadvantage that stable characteristics cannot be maintained over a long period of time.

Therefore, an object of the present invention is to improve the electrical characteristics of electrolytic capacitors and to maintain stable characteristics for a long time by providing a substantially non-aqueous highly conductive electrolytic solution containing an aprotic solvent as a main component. The purpose is to improve the reliability of electrolytic capacitors by maintaining them for a certain period of time.

(Means for Solving the Problems) As a result of extensive research into an electrolyte that is a substantially non-aqueous electrolyte mainly composed of an aprotic solvent and provides high conductivity, the present inventors found that phenylcarboxylic acid The present invention was achieved by discovering that H-alkyl-1-azabicycloalkanium compound salts have high solubility in aprotic solvents, have a high degree of dissociation, and impart high electrical conductivity.

That is, the electrolytic solution for an electrolytic capacitor according to the present invention has a general formula (where m is 2 or 3, n is 2 or 3, p is 1.2 or 3, R7 is an alkyl group having 6 or less carbon atoms, X6,
, X3 represents a group selected from a hydrogen atom, a lower alkyl group, a hydroxy group, a lower alkoxy group, a nitro group, a carboxyl group, or a salt with the same group as the ammonium group in the formula of the carboxyl group). mono- or di-alkyl-1-azabicyclo [m+ n+
p] It is characterized by containing an alkanium compound salt as an electrolyte.

The aprotic solvents used include (1) N-methylformamide, N-methylformamide as an amide type;
, N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, H-ethylacetamide, N,N-diethylacetamide, hexamethylphosphoric amide, (2 ) dimethyl sulfoxide as an oxide type, (3) acetonitrile as a nitrile type, (4) γ- as a cyclic ester and amide type.
Representative examples include butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, and the like.

The polyhydric alcohol compound that 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 teary, and the dihydric alcohol monoalkyl ether compound is methyl cellosolve or a dihydric alcohol compound. It is ethyl cellosolve.

The weight ratio of the polyhydric alcohol compound to the aprotic solvent is (100-50) (0-50), and 100% of the aprotic solvent is appropriate, but up to about 50% of the polyhydric alcohol compound is substantially It may be used as appropriate to avoid product deterioration.

The phenylcarboxylic acid compounds targeted by the present invention are 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. , trimethoxytrimesic acid, prenidic acid, merofanic acid, pyromellitic acid, nitrobenzoic acid, dinitrobenzoic acid, 2.4.6-trinitrobenzoic acid, nitrophthalic acid, nitroisophthalic acid, nitroterephthalic acid, hydroxybenzoic acid, salutyl 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-trihydroxybenzoic acid, 2.4.6- trihydroxybenzoic acid, 6-methylsalicylic acid, 3-methylsalicylic acid,
Examples include, but are not limited to, 0-thymonic acid, orceric acid, hydroxyisophthalic acid, hydroxyterephthalic acid, norhemipic acid, anisic acid, vanillic acid, isovanilic acid, veratramic acid, trimethoxybenzoic acid, and hemipic acid.

Typical examples of N-alkyl-]-azabicycloalkanium compounds are N-alkyl quinuclidinium ethylkyl azabicyclo[2,2,11butanium N-alkyl-1-azabicyclo[3,2,21 nonanium Toalkyl-1-azabicycloC3,3,I]/nanium N-alkyl-1-azabicyclo[3,2,1]octanium N-alkyl-1-azabicycloalkanium compounds include, for example, V, prelobe, etc. 5
Volume 32, page 83 (+937), Berichte No. 7
Volume 2, page 1319 (1939), C^ Grove et al. Helvetica Nami Chikara Acta Volume 37, page 1672 (1
N-alkyl-1-azabicycloalkane is synthesized by the tripromide-ammonia method described in 954) or by the double alkylation method, and this is N-alkylated with an alkyl genide by a conventional method to obtain the corresponding halokene. A N-alkyl-azabicycloalkanium compound can be obtained. This is subjected to electrodialysis using an ion exchange membrane to perform anion exchange, dehalogenation, and desalting to obtain an aqueous solution of an N-alkyl-1-azabicycloalkanium hydroxide compound. Equivalent moles or 2 moles of the desired phenylcarboxylic acid compound are added to the obtained aqueous solution of the N-alkyl-1-azabicycloalkanium hydroxide compound, a neutralization reaction is carried out, and the phenylcarboxylic acid is evaporated to dryness under reduced pressure. Mono- or di-N-alkyl-1-azabicycloalkanium salts of the compounds can be obtained.

The electrolytic solution for an electrolytic capacitor according to the present invention is generally prepared by adding an N-alkyl-1 of a desired phenylcarphonic 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 an azabicycloalkanium salt.

(Example) Examples of the electrolytic solution for electrolytic capacitors according to the present invention will be described below with various aprotic solvents of ethylkyl-1-azabicycloalkanium compound salts of phenylcarboxylic acid compounds or with ethylene glycol or methyl cellosolve (
20 for ethylene glycol monomethyl ether)
The electrical conductivity of the solutions in weight percent is shown in Table 1. As a comparative example, a conventional standard electrolyte (ethylene glycol 78fjf
fi%, water 10%, diammonium adipate 12%)
It shows.

Fudedo people The liquid exhibits higher conductivity than conventional liquids.

Next, electrolytic capacitors were manufactured using the electrolytes of Examples 1 to 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 a separator paper in between to form a cylindrical capacitor element, which was impregnated with the electrolytic solution 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 16V and a rated capacity of 180 μF.

Table 2 shows the initial values of these electrolytic capacitors as well as 110
Capacitance value (μP), tangent of loss angle (tan δ), leakage current (μ
^) (dichotomous value).

λ Table (Effects of the Invention) The electrolytic capacitor using the electrolyte according to the present invention has a low loss value and can maintain stable characteristics even when used at high temperatures for long periods of time, so it can be used at high frequencies and It can be used in power supply devices such as switching regulators that require efficiency, and in various electrical devices that are used at high temperatures for long periods of time.

Patent Applicant: Nippon Chemi-Con Co., Ltd. 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 value of tan δ, is lower than that of the conventional electrolyte.

In addition, since it essentially does not contain water, there will be no abnormal appearance or decrease in capacitance due to increased internal pressure even when placed under high temperature load conditions.
In comparing the initial values and the characteristic values after 1000 hours, the properties of the present invention show very little change.

Claims (7)

[Claims] (1) General formulas in solvents that are mainly aprotic solvents: ▲Mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, m is 2 or 3, n is 2 or 3, p is 1, 2 or 3, R_2 is an alkyl group having 6 or less carbon atoms, X_1,
X_2, X_3 represent a group selected from a hydrogen atom, a lower alkyl group, a hydroxy group, a lower alkoxy group, a nitro group, a carboxyl group, or a salt with the same group as the ammonium group in the formula of the carboxyl group) phenylcarboxylic acid The compound mono- or di-N-alkyl-1-azabicyclo[m
, n, p] An electrolytic solution for an electrolytic capacitor containing an alkanium compound salt as an electrolyte. (2) A solvent mainly composed of an aprotic solvent is 100 to 50 parts by weight of an aprotic solvent and 0 to 50 parts by weight of a polyhydric alcohol compound.
The electrolytic solution for an electrolytic capacitor according to claim 1, comprising parts by weight. (3) The aprotic solvent is N-methylformamide, N,
N-dimethylformamide, N-ethylformamide,
N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide, γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, The electrolytic solution for an electrolytic capacitor according to claim 1 or 2, which is selected from the group of dimethyl sulfoxide, acetonitrile, or a mixture thereof. (4) The electrolytic solution for an electrolytic capacitor according to claim 2, wherein the polyhydric alcohol compound is a dihydric alcohol compound or a monoalkyl ether of a dihydric alcohol compound. (5) The electrolytic solution for an electrolytic capacitor according to claim 2, wherein the dihydric alcohol compound is ethylene glycol and the dihydric alcohol monoalkyl ether compound is methyl cellosolve or ethyl cellosolve. (6) N-alkyl-1-azabicyclo[m,n,p]
Alkanium compounds include N-ethylquinuclidinium, N
The electrolytic solution for an electrolytic capacitor according to claim 1, which is -methylquinuclidium or N-ethyl-1-azabicyclo[3,3,1]nonanium. (7) The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the phenylcarboxylic acid compound is benzoic acid, phthalic acid, salicylic acid, or hemimellitic acid.