JP2001291642A - Electrolyte solution for electrolytic capacitor and element for electrolytic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte solution for electrolytic capacitor and an electrolytic capacitor, where the leakage of an electrolyte solution can be prevented, a solvent be prevented from evaporation in case where it is used at t high temperature and a for a long time, and which have an appropriate service life. SOLUTION: This electrolyte solution is comprised of a solvent, which contains a γ-butyrolactone and an N-hydro cyclic amide (A) represented by a general formula (1) or (2), and an electrolyte (B) which is made of class 3rd amine and salt containing an amidinium or a guadinium cation (a) and a carbonic acid anion (b), and an element for electrolytic capacitor uses this electrolyte solution. (In the formula (1), n is an integer of 3 to 5, and each of methylene groups may have a substituent.) (In the formula (2), m is 1 or 2, and each of methylene groups may have a substituent.).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution used for an electrolytic capacitor and an element using the same.

[0002]

2. Description of the Related Art Conventionally, as an electrolyte for an electrolytic capacitor, an electrolyte using a quaternary ammonium salt of maleic acid or citraconic acid as an electrolyte or an electrolyte using a quaternary alkyl ammonium salt of an aromatic carboxylic acid as an electrolyte. (US Pat. No. 4,715,976), a so-called amidine-based electrolytic solution using a carboxylate of a quaternized compound having an alkyl-substituted amidine group as an electrolyte (International Publication WO95 / 1)
No. 5572). Also, in recent years, for the purpose of prolonging the life at high temperatures, an electrolytic solution in which a quaternary ammonium salt of phthalic acid or maleic acid is dissolved in a mixed solvent of γ-butyrolactone and a high boiling point solvent has been proposed (Japanese Patent Application Laid-Open No. Hei 5 (1993) -520).
-315195).

[0003]

However, US Pat.
In an electrolytic solution in which a quaternary ammonium salt is dissolved, which is disclosed in Japanese Patent Application Laid-Open No. 715976 or Japanese Patent Application Laid-Open No. 5-315195, an alkaline component is generated near a negative electrode of a capacitor due to an electrochemical reaction of the electrolytic solution, which is sealed. As the elasticity of rubber deteriorates, the sealing power of rubber decreases over time,
There was a problem that the internal electrolyte leaked from the negative electrode lead hole.

In an amidine-based electrolyte in which a carboxylate salt of a quaternary compound of an alkyl-substituted amidine group disclosed in International Publication WO 95/15572 is dissolved, the generation of this alkali component is small. Compared to a tetraalkyl quaternary ammonium salt, the effect of preventing leakage of the electrolytic solution is excellent. However, when the solvent is used for a long time at a high temperature, the solvent permeates through the sealing rubber and evaporates, so that the capacitance is greatly reduced with time, and the life characteristics of the electrolytic solution are not sufficiently satisfactory.

[0005] The present invention is to solve the above problems,
An object of the present invention is to provide an electrolytic solution and an electrolytic capacitor for an electrolytic capacitor which can prevent leakage of the electrolytic solution and suppress evaporation of the solvent when used at a high temperature for a long time, and have good life characteristics.

[0006]

That is, in the present invention, the solvent is γ
-Butyrolactone and the following general formula (1) or (2)
Wherein the electrolyte (B) is a salt composed of a tertiary amine, amidinium or guanidinium cation (a) and a carboxylate anion (b). Characteristic electrolytic solution for electrolytic capacitors.

[0007]

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In the formula, n is an integer of 3 to 5, and each methylene group may have a substituent.

[0009]

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In the formula, m is 1 or 2, and each methylene group may have a substituent. Hereinafter, the electrolytic solution for an electrolytic capacitor of the present invention will be described.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The solvent comprises γ-butyrolactone and an N-hydrocyclic amide represented by the general formula (1) or (2). In the general formula (1), n is an integer of 3 to 5, preferably an integer of 3 to 4. Each methylene group may have a substituent. In the general formula (2),
m is 1 or 2, and preferably 1. Each methylene group may have a substituent. Examples of the substituent include: 1) an alkyl group, preferably an alkyl group having 1 to 3 carbon atoms;
For example, a methyl group, an ethyl group, a propyl group, and the like. 2) a hydroxyl group or a hydrocarbon group having a hydroxyl group; for example, a hydroxymethyl group, a hydroxyethyl group and the like; 3) A hydrocarbon group having a carbonyl group; for example, an acetyl group, a methyloxycarbonyl group, an ethyloxycarbonyl group and the like. 4) an alkoxyl group such as a methoxyl group and an ethoxyl group. Preferred as methylene groups are unsubstituted and alkyl-substituted ones.

Specific examples of the N-hydrocyclic amide (A) include the following: unsubstituted N-hydrocyclic amide; 2-pyrrolidinone, 2-pyrrolidinone
Alkyl-substituted N-hydrocyclic amides such as piperidinone and oxindole; 3-methyl-2
-Pyrrolidinone, 4-methyl-2-pyrrolidinone, 5-
Methyl-2-pyrrolidinone, 3-ethyl-2-pyrrolidinone, 3-propyl-2-pyrrolidinone, 3-methyl-
3-hydroxy-2-pyrrolidinone, 4-hydroxy-2-pyrrolidinone, 5-hydroxy-2-pyrrolidinone, 3-hydroxymethyl-2, 3-hydroxy-2-pyrrolidinone; 4-hydroxy-2-pyrrolidinone; -Pyrrolidinone,
3-hydroxy-2-piperidinone, such as a hydrocarbon group-substituted N-hydrocyclic amide having a carbonyl group; 3-acetyl-2-pyrrolidinone, 3-acetyl-2-piperidinone, 3-methylcarboxy-2-pyrrolidinone, etc., an alkoxyl group Substituted N-hydrocyclic amides; 3-methoxy-2-pyrrolidinone, 3-ethoxy-2-pyrrolidinone, 3-ethoxy-2-piperidinone and the like. Of these, preferred are 2-pyrrolidinone, 2-piperidinone, oxindole, 3-methyl-2-pyrrolidinone, 4-methyl-2-pyrrolidinone, 5-methyl-2-pyrrolidinone, and particularly preferred is 2-methyl-2-pyrrolidinone. Pyrrolidinone.

The weight ratio of γ-butyrolactone / compound (A) is usually 5/9 from the viewpoint of electric conductivity.
5 to 95/5, preferably 15/85 to 75/2
5

Further, other known organic solvents may be used in combination. Specific examples of other organic solvents are as follows, and two or more kinds can be used in combination. Water may be added together with these organic solvents as needed. (1) Alcohols monohydric alcohols; monohydric alcohols having 1 to 6 carbon atoms (such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, and furfuryl alcohol), and monohydric alcohols having 7 or more carbon atoms ( Benzyl alcohol, octanol, etc.) dihydric alcohols; dihydric alcohols having 1 to 6 carbon atoms (ethylene glycol, propylene glycol, diethylene glycol, hexylene glycol, etc.), dihydric alcohols having 7 or more carbon atoms (octylene glycol, etc.) Alcohol; trihydric alcohol having 2 to 6 carbon atoms (such as glycerin); alcohol having 4 to 6 or more valent; alcohol having 4 to 6 or more carbon atoms having 2 to 6 carbon (such as hexitol).

(2) Ethers Monoethers (such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monophenyl ether, tetrahydrofuran, and 3-methyltetrahydrofuran), diethers (ethylene glycol Dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.).

(3) Amides Formamides (1-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N
-Diethylformamide, etc.), acetamides (N-
Methylacetamide, N, N-dimethylacetamide,
N-ethylacetamide, N, N-diethylacetamide, etc.), propionamides (N, N-dimethylpropionamide, etc.), hexamethylphosphorylamide and the like. (4) Oxazolidinones; N-methyl-2-oxazolidinone, 3,5-dimethyl-2-oxazolidinone and the like.

(5) Lactones other than γ-butyrolactone α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, δ-valerolactone and the like. (6) Nitriles Acetonitrile, acrylonitrile and the like. (7) Carbonates Ethylene carbonate, propylene carbonate and the like. (8) Others Dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone, aromatic solvents (toluene, xylene, etc.), paraffin solvents (normal paraffin, isoparaffin) and the like.

The content of the other organic solvent is preferably not more than 20% by weight based on the total amount of γ-butyrolactone and the compound (A). When water is used in combination, the content of water is preferably 10% by weight or less based on the total of γ-butyrolactone and the compound (A) from the viewpoint of electric conductivity.

In the electrolyte (B), the tertiary amine, amidinium or guanidinium cation (a) includes the following.

[1] Trialkylamines Trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl n-propylamine, dimethylisopropylamine, methylethyln
-Propylamine, methylethylisopropylamine,
Diethyl n-propylamine, diethylisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tri-tert-butylamine and the like.

[2] Phenyl group-containing amines Dimethylphenylamine, methylethylphenylamine, diethylphenylamine and the like.

[3] Cycloaliphatic amines n-methyl-piperidine, n-methyl-pyrrolidine, n
-Methyl-4-piperidinol, n-methyl-4-piperidone, n-methylmorpholine, n-ethylmorpholine and the like.

[4] imidazoliniums 1,2,3,4-tetramethylimidazolinium, 1,
3,4-trimethyl-2-ethylimidazolinium,
1,3-dimethyl-2,4-diethylimidazolinium, 1,2-dimethyl-3,4-diethylimidazolinium, 1-methyl-2,3,4-triethylimidazolinium, 1,2,3 1,4-tetraethylimidazolinium, 1,2,3-trimethylimidazolinium, 1,3
-Dimethyl-2-ethylimidazolinium, 1-ethyl-2,3-dimethylimidazolinium, 1,2,3-triethylimidazolinium, 4-cyano-1,2,3-
Trimethylimidazolinium, 3-cyanomethyl-1,
2-dimethylimidazolinium, 2-cyanomethyl-
1,3-dimethylimidazolinium, 4-acetyl-
1,2,3-trimethylimidazolinium, 3-acetylmethyl-1,2-dimethylimidazolinium, 4-methylcarboxymethyl-1,2,3-trimethylimidazolinium, 3-methylcarboxymethyl- 1,2
-Dimethyl imidazolinium, 4-methoxy-1,2,2
3-trimethylimidazolinium, 3-methoxymethyl-1,2-dimethylimidazolinium, 4-formyl-
1,2,3-trimethylimidazolinium, 3-formylmethyl-1,2-dimethylimidazolinium, 3-hydroxyethyl-1,2-dimethylimidazolinium,
4-hydroxymethyl-1,2,3-trimethylimidazolinium, 2-hydroxyethyl-1,3-dimethylimidazolinium and the like.

[5] Imidazolium 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,3-trimethylimidazolium, 1,2,2
3,4-tetramethylimidazolium, 1,3-dimethyl-2-ethylimidazolium, 1,2-dimethyl-3
-Ethyl-imidazolium, 1,2,3-triethylimidazolium, 1,2,3,4-tetraethylimidazolium, 1,3-dimethyl-2-phenylimidazolium, 1,3-dimethyl-2-benzylimidazo Ium,
1-benzyl-2,3-dimethyl-imidazolium, 4
-Cyano-1,2,3-trimethylimidazolium, 3
-Cyanomethyl-1,2-dimethylimidazolium, 2
-Cyanomethyl-1,3-dimethyl-imidazolium,
4-acetyl-1,2,3-trimethylimidazolium, 3-acetylmethyl-1,2-dimethylimidazolium, 4-methylcarboxymethyl-1,2,3-trimethylimidazolium, 3-methylcarboxymethyl -1,2-dimethylimidazolium, 4-methoxy-
1,2,3-trimethylimidazolium, 3-methoxymethyl-1,2-dimethylimidazolium, 4-formyl-1,2,3-trimethylimidazolium, 3-formylmethyl-1,2-dimethylimidazolium, 3-hydroxyethyl-1,2-dimethylimidazolium, 4
-Hydroxymethyl-1,2,3-trimethylimidazolium, 2-hydroxyethyl-1,3-dimethylimidazolium

[6] Tetrahydropyrimidiniums 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 1,2,3-trimethyl-1,4,5,6
-Tetrahydropyrimidinium, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium, 1,2,3,5-tetramethyl-1,4,5,6-
Tetrahydropyrimidinium, 8-methyl-1,8-diazabicyclo [5,4,0] -7-undecenium, 5
-Methyl-1,5-diazabicyclo [4,3,0] -5
-Nonenium, 4-cyano-1,2,3-trimethyl-
1,4,5,6-tetrahydropyrimidinium, 3-cyanomethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-cyanomethyl-1,3-
Dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-acetyl-1,2,3-trimethyl-1,4
5,6-tetrahydropyrimidinium, 3-acetylmethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-methylcarboxymethyl-
1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-methylcarboxymethyl-
1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-methoxy-1,2,3-trimethyl-
1,4,5,6-tetrahydropyrimidinium, 3-methoxymethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-formyl-1,2,3
-Trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-formylmethyl-1,2-dimethyl-1,
4,5,6-tetrahydropyrimidinium, 3-hydroxyethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-hydroxymethyl-1,
2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 2-hydroxyethyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium and the like.

[7] dihydropyrimidiniums 1,3-dimethyl-1,4- or -1,6-dihydropyrimidinium [these are 1,3-dimethyl-1,
4 (6) -dihydropyrimidinium, and the same expression is used hereinafter. 1,2,3-trimethyl-1,4
(6) -dihydropyrimidinium, 1,2,3,4-tetramethyl-1,4 (6) -dihydropyrimidinium,
1,2,3,5-tetramethyl-1,4 (6) -dihydropyrimidinium, 8-methyl-1,8-diazabicyclo [5,4,0] -7,9 (10) -undecadie , 5-methyl-1,5-diazabicyclo [4,3,
0] -5,7 (8) -nonadienium, 4-cyano-
1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 3-cyanomethyl-1,2-dimethyl-
1,4 (6) -dihydropyrimidinium, 2-cyanomethyl-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 4-acetyl-1,2,3-trimethyl-
1,4 (6) -dihydropyrimidinium, 3-acetylmethyl-1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 4-methylcarboxymethyl-1,
2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 3-methylcarboxymethyl-1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 4-methoxy-1,2 , 3-Trimethyl-1,4 (6) -dihydropyrimidinium, 3-methoxymethyl-1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 4-
Formyl-1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 3-formylmethyl-1,2-
Dimethyl-1,4 (6) -dihydropyrimidinium, 3
-Hydroxyethyl-1,2-dimethyl-1,4 (6)
-Dihydropyrimidinium, 4-hydroxymethyl-
1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 2-hydroxyethyl-1,3-dimethyl-1,4 (6) -hydropyrimidinium and the like.

[8] Guanidiniums having an imidazolinium skeleton 2-dimethylamino-1,3,4-trimethylimidazolinium, 2-diethylamino-1,3,4-trimethylimidazolinium, 2-diethylamino-1 , 3-Dimethyl-4-ethylimidazolinium, 2-dimethylamino-1-methyl-3,4-diethylimidazolinium, 2-diethylamino-1-methyl-3,4-diethylimidazolinium, 2-diethylamino -1, 3, 4
-Tetraethylimidazolinium, 2-dimethylamino-1,3-dimethylimidazolinium, 2-diethylamino-1,3-dimethylimidazolinium, 2-dimethylamino-1-ethyl-3-methylimidazolinium,
2-diethylamino-1,3-diethylimidazolinium, 1,5,6,7-tetrahydro-1,2-dimethyl-2H-imido [1,2a] imidazolinium, 1,5
-Dihydro-1,2-dimethyl-2H-imide [1,2
a] imidazolinium, 1,5,6,7-tetrahydro-1,2-dimethyl-2H-pyrimido [1,2a] imidazolinium, 1,5-dihydro-1,2-dimethyl-
2H-pyrimido [1,2a] imidazolinium, 2-dimethylamino-4-cyano-1,3-dimethylimidazolinium, 2-dimethylamino-3-cyanomethyl-1
-Methylimidazolinium, 2-dimethylamino-4-
Acetyl-1,3-dimethylimidazolinium, 2-dimethylamino-3-acetylmethyl-1-methylimidazolinium, 2-dimethylamino-4-methylcarboxymethyl-1,3-dimethylimidazolinium, 2 −
Dimethylamino-3-methylcarboxymethyl-1-
Methyl imidazolinium, 2-dimethylamino-4-methoxy-1,3-dimethylimidazolinium, 2-dimethylamino-3-methoxymethyl-1-methylimidazolinium, 2-dimethylamino-4-formyl-1 , 3
-Dimethyl imidazolinium, 2-dimethylamino-3
-Formylmethyl-1-methylimidazolinium, 2-
Dimethylamino-3-hydroxyethyl-1-methylimidazolinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethylimidazolinium and the like.

[9] Guanidiniums having an imidazolium skeleton 2-dimethylamino-1,3,4-trimethylimidazolium, 2-diethylamino-1,3,4-trimethylimidazolium, 2-diethylamino-1,3- Dimethyl-4-ethylimidazolium, 2-dimethylamino-
1-methyl-3,4-diethylimidazolium, 2-diethylamino-1-methyl-3,4-diethylimidazolium, 2-diethylamino-1,3,4-tetraethylimidazolium, 2-dimethylamino-1,3 -Dimethylimidazolium, 2-diethylamino-1,3-dimethylimidazolium, 2-dimethylamino-1-ethyl-3-methylimidazolium, 2-diethylamino-
1,3-diethylimidazolium, 1,5,6,7-tetrahydro-1,2-dimethyl-2H-imide [1,2
a] imidazolium, 1,5-dihydro-1,2-dimethyl-2H-imide [1, 2a] imidazolium, 1,
5,6,7-tetrahydro-1,2-dimethyl-2H-
Pyrimido [1,2a] imidazolium, 1,5-dihydro-1,2-dimethyl-2H-pyrimido [1,2a] imidazolium, 2-dimethylamino-4-cyano-1,
3-dimethylimidazolium, 2-dimethylamino-3
-Cyanomethyl-1-methylimidazolium, 2-dimethylamino-4-acetyl-1,3-dimethylimidazolinium, 2-dimethylamino-3-acetylmethyl-
1-methylimidazolium, 2-dimethylamino-4-
Methylcarboxymethyl-1,3-dimethylimidazolium, 2-dimethylamino-3-methylcarboxymethyl-1-methylimidazolium, 2-dimethylamino-4-methoxy-1,3-dimethylimidazolium,
2-dimethylamino-3-methoxymethyl-1-methylimidazolium, 2-dimethylamino-4-formyl-
1,3-dimethylimidazolium, 2-dimethylamino-3-formylmethyl-1-methylimidazolium, 2
-Dimethylamino-3-hydroxyethyl-1-methylimidazolium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethylimidazolium and the like.

[10] Guanidiniums having a tetrahydropyrimidinium skeleton 2-dimethylamino-1,3,4-trimethyl-1,
4,5,6-tetrahydropyrimidinium, 2-diethylamino-1,3,4-trimethyl-1,4,5,6-
Tetrahydropyrimidinium, 2-diethylamino-
1,3-dimethyl-4-ethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-1-methyl-3,4-diethyl-1,4,5,6-tetrahydropyrimidinium , 2-diethylamino-1-methyl-
3,4-diethyl-1,4,5,6-tetrahydropyrimidinium, 2-diethylamino-1,3,4-tetraethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-1 , 3-Dimethyl-1,4,
5,6-tetrahydropyrimidinium, 2-diethylamino-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-1-ethyl-
3-methyl-1,4,5,6-tetrahydropyrimidinium, 2-diethylamino-1,3-diethyl-1,
4,5,6-tetrahydropyrimidinium, 1,3
4,6,7,8-hexahydro-1,2-dimethyl-2
H-imide [1, 2a] pyrimidinium, 1, 3, 4,
6-tetrahydro-1,2-dimethyl-2H-imide [1,2a] pyrimidinium, 1,3,4,6,7,8
-Hexahydro-1,2-dimethyl-2H-pyrimido [1,2a] pyrimidinium, 1,3,4,6-tetrahydro-1,2-dimethyl-2H-pyrimido [1,2
a] pyrimidinium,

2-dimethylamino-4-cyano-1,3
-Dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-cyanomethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4- Acetyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-acetylmethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium,
2-dimethylamino-4-methylcarboxymethyl-
1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-methylcarboxymethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium, 2- Dimethylamino-4-methoxy-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-methoxymethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium Midinium, 2-dimethylamino-4-formyl-1,3
-Dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-formylmethyl-1-
Methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-hydroxyethyl-1-
Methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4-hydroxymethyl-1,
3-dimethyl-1,4,5,6-tetrahydropyrimidinium and the like.

[11] Guanidiniums having a dihydropyrimidinium skeleton 2-dimethylamino-1,3,4-trimethyl-1,4
(6) -dihydropyrimidinium, 2-diethylamino-1,3,4-trimethyl-1,4 (6) -dihydropyrimidinium, 2-diethylamino-1,3-dimethyl-4-ethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-1-methyl-3,4-diethyl-1,4 (6) -dihydropyrimidinium, 2-diethylamino-1-methyl-3,4-diethyl- 1,4
(6) -dihydropyrimidinium, 2-diethylamino-1,3,4-tetraethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-1,3-dimethyl-1,4 (6) -Dihydropyrimidinium, 2-diethylamino-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-1-ethyl-
3-methyl-1,4 (6) -dihydropyrimidinium,
2-diethylamino-1,3-diethyl-1,4 (6)
-Dihydropyrimidinium, 1,6,7,8-tetrahydro-1,2-dimethyl-2H-imide [1,2a] pyrimidinium, 1,6-dihydro-1,2-dimethyl-
2H-imide [1,2a] pyrimidinium, 1,6
7,8-tetrahydro-1,2-dimethyl-2H-pyrimido [1,2a] pyrimidinium, 1,6-dihydro-
1,2-dimethyl-2H-pyrimido [1,2a] pyrimidinium, 2-dimethylamino-4-cyano-1,3-
Dimethyl-1,4 (6) -dihydropyrimidinium,

2-dimethylamino-3-cyanomethyl-
1-methyl-1,4 (6) -dihydropyrimidinium,
2-dimethylamino-4-acetyl-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-3-acetylmethyl-1-methyl-1,4
(6) -dihydropyrimidinium, 2-dimethylamino-4-methylcarboxymethyl-1,3-dimethyl-
1,4 (6) -dihydropyrimidinium, 2-dimethylamino-3-methylcarboxymethyl-1-methyl-
1,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-methoxy-1,3-dimethyl-1,4
(6) -dihydropyrimidinium, 2-dimethylamino-3-methoxymethyl-1-methyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-formyl-1,3-dimethyl- 1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-formylmethyl-1-methylamino-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-hydroxyethyl -1-methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethyl-1,4 (6) -dihydropyrimidinium and the like. Of these, preferred are imidazolinium cations, and particularly preferred are
1,2,3,4-tetramethylimidazolinium, 1,
2,3-trimethylimidazolinium, 1-ethyl-
2,3-dimethylimidazolinium and 2-dimethylamino-1,3,4-trimethylimidazolinium.
The tertiary amine, amidinium or guadinium cation (a) in the present invention may be used alone or in combination of two or more.

In the electrolyte, the carboxylic acid anion (b) includes the following carboxylic acid anions.

[1] Fatty monocarboxylic acid; formic acid, acetic acid,
Propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid,
Enanthic acid, caprylic acid, berargonic acid, lauric acid,
Myristic acid, stearic acid, behenic acid, acrylic acid,
Methacrylic acid, oleic acid, etc. [2] Aromatic monocarboxylic acids; benzoic acid, cinnamic acid, naphthoic acid and the like. [3] Aliphatic polycarboxylic acids; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, itaconic acid and the like. [4] Aromatic polycarboxylic acids; phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid and the like. [5] aliphatic oxycarboxylic acids; glycolic acid, lactic acid,
Tartaric acid and the like. [6] Aromatic oxycarboxylic acids; salicylic acid, mandelic acid and the like. [7] Other polycarboxylic acids; thiodipropionic acid,
Cyclobutene-1,2-dicarboxylic acid, cyclopentene-1,2-dicarboxylic acid, furan-2,3-dicarboxylic acid, bicyclo [2,2,1] hept-2-ene-2,3
Dicarboxylic acid, bicyclo [2,2,1] hepta-2,
5-diene-2,3-dicarboxylic acid and the like. Among these, preferred are aromatic monocarboxylic acids and aromatic polycarboxylic acids which have high specific conductivity and are thermally stable, and particularly preferred are benzoic acid and phthalic acid. The carboxylate anion (b) in the present invention may be used alone or in combination of two or more.

The content of the electrolyte (B) in the electrolytic solution for an electrolytic capacitor of the present invention is the total of γ-butyrolactone, the compound (A) and the electrolyte (B) from the viewpoint of the electric conductivity and the solubility in the electrolytic solution solvent. On the other hand, usually 5 to 70% by weight,
Preferably it is 10 to 40% by weight. If necessary together with the electrolyte (B) in the electrolytic solution of the present invention, other known 4
A quaternary ammonium salt (eg, a tetraalkyl quaternary ammonium salt) may be used in combination. When used in combination, the content of the other salt is usually 30% by weight or less, preferably 10% by weight or less of the electrolyte (B) from the viewpoint of the solubility of the electrolyte (B) in the electrolyte solvent. .

The pH of the electrolytic solution of the present invention is usually 3 to 12, preferably 6 to 11. When producing the electrolyte (B), the pH of the electrolytic solution should be within this range (for example, the pH of the anion). Type and usage amount) are selected. For example, when a partial ester of a polybasic acid such as polycarboxylic acid is used as the anion component, it is necessary to pay attention to pH adjustment.
The pH of the electrolytic solution is an analytical value at 25 ° C. of the undiluted electrolytic solution.

If necessary, various additives commonly used in the electrolytic solution can be added to the electrolytic solution of the present invention.
Examples of the additive include a phosphoric acid derivative (eg, phosphoric acid, phosphate ester, etc.), a boric acid derivative (eg, boric acid,
Complex compounds of boric acid and polysaccharides (such as mannitol and sorbite), complex compounds of boric acid and polyhydric alcohols (such as ethylene glycol and glycerin), and nitro compounds (for example, o-nitrobenzoic acid, p- Nitrobenzoic acid, m-nitrobenzoic acid, o-nitrophenol, p-
Nitrophenol), and the like, and the amount of addition is usually 10% by weight or less of the electrolyte (B) from the viewpoint of electric conductivity and solubility in the electrolyte solvent.

The electrolytic solution in the present invention is used for an element for an electrolytic capacitor. The element for the electrolytic capacitor is not particularly limited.For example, in a roll-up type aluminum electrolytic capacitor, a separator is interposed between an anode aluminum foil and a cathode aluminum foil each having a dielectric layer made of aluminum oxide formed on a surface thereof. It may be a capacitor element or the like configured by winding, and this element is impregnated with the electrolyte of the present invention as a driving electrolyte, and the capacitor element is housed in, for example, a bottomed cylindrical aluminum case. After that, the opening of the aluminum case is sealed with a sealing material to form an aluminum electrolytic capacitor.

[0039]

EXAMPLES Next, specific examples of the present invention will be described, but the present invention is not limited to these examples.

Examples 1 to 4 and Comparative Examples 1 to 3 Table 1 shows the composition and electric conductivity of the electrolytes of Examples 1 to 4 and Comparative Examples 1 to 3 of the present invention. ° C, the rate of change in electrical conductivity after performing a heat resistance test for 10 hours (= 100 × ([specific conductivity before heat resistance test (initial value)] − [specific conductivity after heat resistance test]) / [heat resistance test Previous specific conductivity (initial value)] Unit is “%”), 10 cm
Using ^two etching aluminum foil, a constant current method (2 mA)
5 shows the discharge voltage (withstand voltage) of the electrolytic solution in FIG.

[0041]

[Table 1]

Examples 5 to 8 and Comparative Examples 4 to 6 Roll-up type aluminum electrolytic capacitors (rated voltage: 6.3 V, static voltage) using the electrolytes of Examples 1 to 4 and Comparative Examples 1 to 3 of the present invention. Capacity: 220 μF, size: φ6.5
mm × L4.5 mm). Peroxide vulcanized butyl rubber was used as the sealing rubber. The prepared aluminum electrolytic capacitor was left at 125 ° C. for 1000 hours for 20 hours.
00 hours, 3000 hours after the capacitance change rate (ΔC
(%)), Loss angle tangent (tan δ (%)), and leakage current (LC (μA)). Changes in product weight (△
W (mg)) was taken as the dry-up property of the electrolytic solution. Table 2 shows the results. Further, as a liquid leakage test, a moisture resistant width of 85
A rated voltage was applied at a temperature of 85 ° C. and a relative humidity of 85%, and the state of the sealed portion after 3000 hours was observed. Table 3 shows the results.

[0043]

[Table 2]

[0044]

[Table 3]

As is clear from Table 2, the electrolytes of Examples 1 to 4 of the present invention were used for 1000 hours, 2000 hours, and 30 hours.
Even after the lapse of 00 hours, all the characteristics are good, and it can be seen that the change in capacitance is small as compared with the electrolytes of Comparative Examples 1 and 3. As is evident from the change in product weight (ΔW), the electrolytic solution of the present invention has improved dry-up properties, and the change in capacitance due to the disappearance of the electrolytic solution is suppressed. Furthermore, the ethylene glycol (E
In the case of G), the specific conductivity decreases due to the esterification reaction (Table 1), and tan δ increases (Table 2), but the 2-pyrrolidinone used in the present example is stable even at a high temperature. Therefore, tan δ has no problem. As shown in Table 3, when 2-pyrrolidinone was contained as in Examples 1 to 4, the liquid leakage was not inferior to the comparative example, and sufficient liquid leakage resistance was exhibited. Moreover, rather than containing 2-pyrrolidinone, the production of hydroxybutyric acid due to the hydrolysis of γ-butyrolactone can be suppressed, and a decrease in the sealing performance due to the accumulation of the product in the sealing portion can be suppressed. From the above results, a highly reliable aluminum electrolytic capacitor can be formed by using the electrolytic solution of the present invention.

According to the electrolytic solution for an electrolytic capacitor of the present invention, N-hydrocyclic amide, which is hardly compatible with butyl rubber, which is a material of the sealing rubber, and has a high boiling point is used as a secondary solvent for γ-butyrolactone. Transpiration and transpiration are suppressed. When hydroxide ions are generated as a result of the electrochemical reaction in the electrolytic solution, the hydroxide ions and N—C =
Since the electrolytic product disappears promptly by the reaction with the amidine group of N and the decomposition and ring opening, there is no deterioration or corrosion of the resin, rubber or metal constituting the capacitor. Furthermore, the production of hydroxybutyric acid due to the hydrolysis of γ-butyrolactone is suppressed, the sealing performance is prevented from deteriorating due to the accumulation of the product in the sealing portion, and the electrolyte does not leak.

[0047]

The electrolytic solution of the present invention has the above-described structure, so that evaporation of the electrolytic solution solvent can be suppressed, good life characteristics can be obtained, and problems such as leakage of the electrolytic solution can be improved. High performance can be achieved.

Continuing on the front page (72) Inventor Kazushi Shiono 11-11, Hitotsubashi-Honcho, Higashiyama-ku, Kyoto City Inside Sanyo Kasei Kogyo Co., Ltd. (72) Inventor Hiroyuki Matsuura 1006 Kazuma Kazuma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Yuichiro Tsubaki 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideki Shimamoto 1006 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A solvent comprising γ-butyrolactone and an N-hydrocyclic amide (A) represented by the following general formula (1) or (2), wherein the electrolyte (B) is a tertiary amine, amidinium or An electrolytic solution for an electrolytic capacitor, which is a salt composed of an azinium cation (a) and a carboxylate anion (b). Embedded image [In the formula, n is an integer of 3 to 5, and each methylene group may have a substituent. [Chemical formula 2] [In the formula, m is 1 or 2, and each methylene group may have a substituent. ] 2. The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the N-hydrocyclic amide (A) is 2-pyrrolidinone. 3. The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the cation (a) is an imidazolinium cation. 4. The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the carboxylate anion (b) is an aromatic carboxylic acid. 5. The electrolytic solution for an electrolytic capacitor according to claim 4, wherein the carboxylate anion (b) is benzoic acid or phthalic acid. 6. An element for an electrolytic capacitor, comprising the electrolytic solution for an electrolytic capacitor according to claim 1. Description: