JP2672125B2 - Electrolyte for electrolytic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention contains an N-alkyl-1-azabicycloalkanium compound salt of a phenylcarboxylic acid compound as an electrolyte in a solvent mainly composed of an aprotic solvent. The present invention relates to an electrolytic solution for electrolytic capacitors.

(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, and uses the oxide film layer as a derivative, and the surface of the oxide film layer is filled with an electrolyte. A layered electrolytic solution is brought into contact with the layer, and an electrode for collecting current, which is usually called a cathode, is arranged.

The electrolytic solution for electrolytic capacitors directly contacts the dielectric layer as described above and acts as a true cathode. That is, the electrolytic solution is interposed between the dielectric layer of the electrolytic capacitor and the collecting cathode, and the resistance of the electrolytic solution is inserted in series with the electrolytic capacitor. Therefore, the characteristic is a major factor affecting the characteristics of the electrolytic capacitor. For example, when the electric conductivity of the electrolytic solution is low, there is a drawback that the equivalent series resistance inside the electrolytic capacitor is increased and the high frequency characteristics and the loss characteristics are deteriorated. From such a background, an electrolyte having a high conductivity is required, and as a conventionally known high conductivity electrolyte, an organic acid such as adipic acid or a salt thereof is dissolved in a glycol or an alcohol such as ethylene glycol. Things are used mainstream for normal use.

(Problems to be Solved by the Invention) With the recent increase in the range of use of electronic devices, there is an increasing demand for improvement and improvement of electrolytic capacitor performance, and the current electrical conductivity of electrolytic solutions is not sufficient. In particular, in the case of the current electrolytic solution, when the desired electric conductivity cannot be obtained, or when using an electrolyte having low solubility, it is attempted to intentionally add water to improve the electric conductivity. .

However, when the electrolytic capacitor is used for a long time at high temperature, which is higher than conventional products, the presence of water in the electrolyte causes deterioration of the dielectric film layer and internal vapor of the electrolytic capacitor. There is a drawback in that the pressure is increased, the sealing part is damaged, and the electrolyte evaporates, resulting in deterioration of the service life, and stable characteristics cannot be maintained for a long time.

Therefore, an object of the present invention is to improve the electrical characteristics of an electrolytic capacitor and to provide stable characteristics by providing a substantially non-aqueous electrolytic solution mainly composed of an aprotic solvent. It is to improve the reliability of the electrolytic capacitor by maintaining the time.

(Means for Solving the Problems) The inventors of the present invention have conducted diligent research on an electrolyte which is a substantially non-aqueous electrolyte solution mainly composed of an aprotic solvent and has high conductivity, and as a result, The present invention has been accomplished by finding that the N-alkyl-1-azabicycloalkanium compound salt has a high solubility in an aprotic solvent, a high dissociation degree, and a high electric conductivity.

That is, the electrolytic solution for an electrolytic capacitor according to the present invention has a general formula: (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 , and X ₃ are hydrogen atoms, lower alkyl. Group, a hydroxy group, a lower alkoxy group, a nitro group, a carboxyl group or a carboxyl group or a group selected from a salt with the same group as the ammonium group in the formula)).
It is characterized by containing an N-alkyl-1-azabicyclo [m, n, p] alkanium compound salt as an electrolyte.

Examples of aprotic solvents used include: (1) N-methylformamide, N, N
-Dimethylformamide, N-ethylformamide, 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 system, (4) cyclic ester, amide system Typical examples thereof include γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate and propylene carbonate.

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, the dihydric alcohol compound is ethylene glycol, and the dihydric alcohol monoalkyl ether compound is methylcellosolve. Or ethylcellosolve.

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

The phenylcarboxylic acid compounds targeted by the present invention are benzoic acid, toluic acid, ethylbenzoic acid, cumic acid, hemelitic acid, mesitylene acid, dulylic acid, phthalic acid, isophthalic acid, terephthalic acid, 5-methylisophthalic acid, and hemimelitic acid. , Trimellitic acid, trimesic acid, prenitic acid, melophanic acid, pyromellitic acid, nitrobenzoic acid, dinitrobenzoic acid, 2,4,6-trinitrobenzoic 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-trihydroxybenzoic acid, 2,4,6-trihydroxybenzoic acid, 6-methylsalicylic acid, 3-methylsalicylic acid, o-timonic acid, orseric acid, hydroxyisophthalic acid , Hydroxyterephthalic acid, norhemipinic acid, anisic acid, vanillic acid, isovanillic acid, veratramic acid, trimethoxybenzoic acid,
And hemipic acid, but not limited to these.

Representative compound examples of N-alkyl-1-azabicycloalkanium compounds include: N-alkyl-1-azabicycloalkanium compounds are described, for example, in V. Prelog and the like: Annalen Vol.
P. 83 (1937), et al .: Berichte, Vol. 72, p. 1319 (1939), CA Gloves, etc .: Helvetica Timica Acta, Vol. 37, p. 1672 (1954).
N-alkyl-1-azabicycloalkane is synthesized by an ammonia method or a double alkylation method, and this is N-alkylated with an alkyl halide by an ordinary method to obtain a corresponding halogenated N-alkyl-1-azabicycloalkane. Can be obtained. This is subjected to electrodialysis using an ion exchange membrane, anion exchange is performed, and dehalogenation and desalting are performed to obtain an aqueous solution of a N-alkyl-1-azabicycloalkanium hydroxide compound. To the obtained aqueous solution of N-alkyl-1-azabicycloalkanium hydroxide, is added 1 mole or 2 moles of a desired phenylcarboxylic acid compound,
It is possible to obtain a mono- or di-N-alkyl-1-azabicycloalkanium salt of a phenylcarboxylic acid compound by neutralizing and evaporating to dryness under reduced pressure.

The electrolytic solution for the electrolytic capacitor according to the present invention is generally,
It can be obtained by adding and dissolving the desired N-alkyl-1-azabicycloalkanium salt of a phenylcarboxylic acid compound in a solvent prepared by mixing a polyhydric alcohol compound or a monoalkyl ether compound thereof as needed with an aprotic solvent.

(Examples) Examples of the electrolytic solution for an electrolytic capacitor according to the present invention will be described below with reference to N-alkyl-1 of a phenylcarboxylic acid compound.
-Azabicycloalkanium compound salts against various aprotic solvents or ethylene glycol or methyl cellosolve (ethylene glycol monomethyl ether)
The conductivity of the 20 wt% solution is shown in Table 1. As a comparative example, a conventional standard electrolyte (78% by weight of ethylene glycol, 10% of water, and 12% of diammonium adipate) is shown.

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

Next, electrolytic capacitors were manufactured using the electrolytic solutions of Examples 1 to 10 and Comparative Example, and their characteristics were compared.

The manufactured electrolytic capacitor was formed by using an aluminum foil as an anode and a cathode, and overlapping and winding a separator paper therebetween to form a cylindrical capacitor element, and impregnating the electrolytic solution of each of the examples and comparative examples. It is housed in an outer case and sealed.

Each uses the same capacitor element, and has a rated voltage of 16 V and a rated capacity of 180 μF.

Table 2 shows the initial values of these electrolytic capacitors as well as 110
Capacitance value (μF), tangent of loss angle (tan δ), leakage current (μA) after 1000 hours from application of rated voltage at ℃
(Binary value).

As is clear from the results of this test, since the conductivity of the electrolytic solution of the present invention is high, the loss compared to the conventional one, that is,
The value of tan δ decreases.

In addition, since it does not essentially contain water, even under a high temperature load state, there is no appearance abnormality or decrease in capacitance due to an increase in internal pressure, and even when comparing the initial value and the characteristic value after 1000 hours, the present invention Changes very little.

(Effects of the Invention) The electrolytic capacitor using the electrolytic solution according to the present invention has a low loss value and can maintain stable characteristics even when used at high temperature for a long time, so that it is required to be used at a high frequency and high in efficiency. It can be used for a power supply device such as a switching regulator and various electric devices used at high temperature for a long time.

Claims (7)

(57) [Claims] [1] A solvent comprising an aprotic solvent as a main component and a general formula: (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 , and X ₃ are hydrogen atoms, lower alkyl. Group, a hydroxy group, a lower alkoxy group, a nitro group, a carboxyl group or a carboxyl group or a group selected from salts with the same group as the ammonium group in the formula)).
An electrolytic solution for an electrolytic capacitor, which contains an N-alkyl-1-azabicyclo [m, n, p] alkanium compound salt as an electrolyte. 2. A solvent mainly comprising an aprotic solvent comprises 100 to 50 parts by weight of an aprotic solvent and 0 to 50 parts of a polyhydric alcohol compound.
2. The electrolytic solution for an electrolytic capacitor according to claim 1, comprising: parts by weight. 3. An aprotic solvent comprising N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, The electrolysis according to claim 1 or 2, wherein the electrolysis is selected from the group consisting of N, N-diethylacetamide, γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, acetonitrile, and a mixture thereof. Electrolyte for capacitors. 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 the 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 methylcellosolve or ethylcellosolve. 6. N-alkyl-1-azabicyclo [m, n,
2. The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the [p] alkanium compound is N-ethylquinuclidinium, N-methylquinuclidium, N-ethyl-1-azabicyclo [3,3,1] nonanium. 7. The phenylcarboxylic acid compound is benzoic acid, phthalic acid, salicylic acid, or hemimellitic acid.
The electrolytic solution for an electrolytic capacitor according to the above.