JPH08321442A - Aluminum electrolytic capacitor - Google Patents

Abstract

PURPOSE: To provide a highly reliable aluminum electrolytic capacitor which can prevent electrolytic solution from leaking to an outside by reducing influence of electrolysis reaction of electrolytic solution during reverse voltage application and improving stability of a sealing part at a high temperature. CONSTITUTION: The title device is provided with a capacitor element which is formed by winding an anode foil and a cathode foil together with a separator and infiltrating driving electrolytic solution therein, a bottomed tubular metallic case for containing the capacitor element and a sealing body for sealing an opening part of the metallic case. As for driving electrolytic solution, electrolytic solution which is formed by dissolving quaternary salt of compound with alkyl displacement amidine group of phthalic acid and/or maleic acid to organic solvent containing γ-butylolactone is used, and as for a sealing body, an elastic body which is formed by adding peroxide as a curing agent to butyl rubber polymer comprised of copolymer of isobutylene, isoprene and divinylbenzene is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum electrolytic capacitor used in various electronic devices.

[0002]

2. Description of the Related Art As a driving electrolytic solution in a conventional aluminum electrolytic capacitor, a solution prepared by dissolving an organic acid, an inorganic acid or a salt thereof as an electrolyte in a solvent such as .gamma.-butyrolactone or N, N-dimethylformamide is used. And an electrolytic solution using a quaternary ammonium salt of maleic acid or citraconic acid as an electrolyte (Japanese Patent Publication No. 3-6646),
An electrolyte solution (Japanese Patent Publication No. 3-8092) using a quaternary ammonium salt of an aromatic carboxylic acid as an electrolyte is known.

Further, as a sealing member, a sulfur-vulcanized ethylene-propylene copolymer or butyl rubber is known, and as a sealing member having excellent thermal stability, a peroxide-vulcanized butyl rubber (JP-A-62-62). No. 276819) is known.

[0004]

However, in the above-described conventional aluminum electrolytic capacitor, when an excessive reverse voltage is applied to the capacitor element, excess hydroxide generated by electrolysis of the quaternary ammonium salt is generated. When used at high temperature for a long time due to the influence of ions, the internal pressure of the capacitor may rise, which may lead to leakage of the electrolytic solution from the sealing portion.

The present invention solves the above-mentioned conventional problems, and reduces the influence of the electrolysis reaction of the electrolytic solution at the time of applying a reverse voltage, and enhances the stability of the sealing portion at high temperature, thereby improving the electrolytic solution. It is an object of the present invention to provide a highly reliable aluminum electrolytic capacitor capable of preventing leakage of the aluminum oxide to the outside.

[0006]

In order to achieve the above object, the aluminum electrolytic capacitor of the present invention comprises a capacitor element obtained by winding an anode foil and a cathode foil together with a separator and impregnating a driving electrolytic solution, A bottomed cylindrical metal case for accommodating the capacitor element and a sealing body for sealing the opening of the metal case are provided, and phthalic acid and / or maleic acid is added to the organic solvent containing γ-butyrolactone as the driving electrolyte. Using an electrolytic solution prepared by dissolving a quaternary salt of a compound having an alkyl-substituted amidine group of an acid as an electrolyte, and a butyl rubber polymer composed of a copolymer of isobutylene, isoprene and divinylbenzene as the sealing body, and as a vulcanizing agent An elastic body obtained by adding a peroxide is used.

[0007]

According to the above means, (1) phthalic acid and / or γ-butyrolactone-containing organic solvent are used as the driving electrolyte.
Alternatively, since an electrolytic solution obtained by dissolving a quaternary salt of a compound having an alkyl-substituted amidine group of maleic acid as an electrolyte is used, even when hydroxide ions are generated by an electrolytic reaction in the electrolytic solution, Hydroxide ion and N-C-N
The reaction with the amidine group and the decomposition ring-opening causes the electrolytic product to disappear promptly, which results in the occurrence of an excessive reverse voltage, etc., as compared with the case where a tetraalkylammonium salt is used as the electrolyte. Since the influence of the easy electrolysis reaction can be reduced, the sealing performance of the capacitor can be improved. (2) Since peroxide-vulcanized butyl rubber used for the sealing body has excellent thermal stability, it can be used when an aluminum electrolytic capacitor is used at high temperature for a long time as compared with sulfur-vulcanized butyl rubber. In addition, the sealing force (rubber elasticity) is not significantly reduced, and stable sealing performance can be obtained over a long period of time, whereby leakage of the electrolytic solution from the sealing portion, which tends to occur when the internal pressure rises, can be suppressed.

As described above, due to the synergistic effect of the above items (1) and (2), it is possible to reduce the influence of the electrolysis reaction of the electrolytic solution, which tends to occur when a reverse voltage is applied to the capacitor, and to increase the temperature. It is possible to maintain a stable sealing force even underneath and prevent leakage of the electrolytic solution to the outside.

[0009]

EXAMPLES An example of the present invention will be described below.

The basis of the present invention is that a capacitor element obtained by winding an anode foil and a cathode foil together with a separator and impregnating a driving electrolyte solution, a cylindrical metal case having a bottom and containing the capacitor element, And a sealing body for sealing the opening of the metal case, wherein γ-is used as the driving electrolytic solution.
An electrolytic solution obtained by dissolving a quaternary salt of a compound having an alkyl-substituted amidine group of phthalic acid and / or maleic acid as an electrolyte in an organic solvent containing butyrolactone is used, and isobutylene, isoprene, and divinylbenzene are used as the sealing body. It is an aluminum electrolytic capacitor using an elastic body obtained by adding a peroxide as a vulcanizing agent to a butyl rubber polymer made of a polymer.

Examples of the quaternary salt of a compound having an alkyl-substituted amidine group used in the driving electrolytic solution of the aluminum electrolytic capacitor of the present invention are quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group. Other examples include imidazoline compounds, imidazole compounds, benzimidazole compounds, and alicyclic pyrimidine compounds. Specifically, 1-methyl-1,8-diazabicyclo [5,4,0] undecene-7,1-methyl-1,5, which can provide an aluminum electrolytic capacitor with high conductivity and low loss, is provided.
-Diazabicyclo [4,3,0] nonene-5,1,2,
3-trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,3-dimethyl-2-
Ethyl-imidazolinium, 1,3,4-trimethyl-
2-ethylimidazolinium, 1,3-dimethyl-2-
Heptyl imidazolinium, 1,3-dimethyl-2-
(-3′heptyl) imidazolinium, 1,3-dimethyl-2-dodecylimidazolinium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium,
1,3-Dimethylimidazolium and 1,3-dimethylbenzimidazolium are preferable.

As the solvent of the driving electrolytic solution in the aluminum electrolytic capacitor of the present invention, it is desirable to use electrochemically stable γ-butyrolactone as the main solvent. In addition to this, another organic solvent compatible with γ-butyrolactone may be mixed as a sub-solvent for the purpose of improving low temperature characteristics and improving discharge voltage.

As the secondary solvent, a polyhydric alcohol solvent;
Ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, glycerin,
Polyoxyalkylene polyol, lactone solvent; γ
-Valerolactone, delta-valerolactone, 3-methyl-
1,3-oxazolidin-2-one, 3-ethyl-1,
3-oxazolidin-2-one, water, amide solvent; N
-Methylformamide, N, N-dimethylformamide, N-methylacetamide, ether solvent; methylal, 1,2-dimethoxyethane, 1-ethoxy-2-
Methoxyethane, 1,2-diethoxyethane, nitrile-based solvent; acetonitrile, 3-methoxypropionitrile, furan-based solvent; 2,5-dimethoxytetrahydrofuran, 2-imidazolidinone-based solvent; 1,3-dimethyl-2 -Imidazolidinone may be used alone or as a mixed solvent of two or more kinds. In the case of a mixed solvent system, the content of the sub-solvent is preferably 40 parts or less with respect to 100 parts of γ-butyrolactone. If the content of the sub-solvent exceeds 40 parts, the electrochemical stability of the driving electrolyte is lowered,
When the reverse voltage is applied, the rise in the internal pressure of the capacitor also becomes large, and a sufficient effect cannot be obtained.

As the electrolyte salt, it is desirable to use a salt of an electrochemically stable compound of phthalic acid and / or maleic acid having an alkyl-substituted amidine group. Electrolytes other than phthalic acid and maleic acid produce a large amount of gas when a reverse voltage is applied, and the internal pressure of the capacitor rises at this time, resulting in insufficient effects.

The water content of the capacitor element in the aluminum electrolytic capacitor of the present invention is usually less than 10% based on the weight of the impregnated electrolytic solution. If the water content is 10% or more, the electrolysis reaction is promoted and the internal pressure of the capacitor rises, so that a sufficient effect cannot be obtained.

If necessary, various additives may be mixed in the driving electrolytic solution of the aluminum electrolytic capacitor of the present invention.
As additives, phosphorus compounds [phosphoric acid, phosphoric acid ester, etc.], boric acid compounds [boric acid, complex compounds of boric acid and polysaccharides (mannite, sorbite, etc.), boric acid and polyhydric alcohols (Ethylene glycol, glycerin, etc.)], and nitro compounds [p-nitrobenzoic acid, p-nitrophenol, etc.]. By mixing these additives, the repairability of the aluminum oxide film can be improved. As a result, the electrolytic reaction of the electrolytic solution can be suppressed, and the sealing performance can be further improved.

The aluminum electrolytic capacitor of the present invention may have a bar-shaped body of the terminal portion subjected to anticorrosion treatment. By subjecting the rod-shaped body to anticorrosion treatment, the electrolysis current can be suppressed, so that the sealing performance can be further improved. The anticorrosion treatment on the rod-shaped body is preferably performed on both ends of the anode side and the cathode side, but the treatment may be performed on only one side. Further, as a means for anticorrosion treatment, anodizing treatment in an aqueous solution is simple and preferable.

As the sealing body, an elastic body obtained by adding 1 to 20 parts of a peroxide as a vulcanizing agent to a butyl rubber polymer made of a copolymer of isobutylene, isoprene and divinylbenzene is preferable. As the peroxide, dicumyl peroxide is desirable because it can provide sufficient rubber elasticity and can provide a sealing body with stable sealing performance at high temperatures. In addition, vulcanization methods other than peroxide vulcanization do not provide sufficient sealability because the rubber elasticity significantly decreases when left at high temperature for a long time.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The composition of the driving electrolytic solution used in the examples is as follows. Electrolyte solution A: γ-butyrolactone 100 parts Mono 1-methyl-1,8-diazabicyclo [5,4,0] undecene-7 phthalate 30 parts p-Nitrobenzoic acid 1 part The above compounds are mixed and dissolved.

Electrolyte solution B: γ-butyrolactone 100 parts Mono 1-methyl-1,5-diazabicyclo [4,3,0] nonene-5 phthalate 30 parts Monobutyl phosphate ester 1 part The above compounds are mixed and dissolved. .

Electrolyte C: γ-butyrolactone 100 parts Mono 1,2,3-trimethylimidazolinium maleate 30 parts p-nitrobenzoic acid 1 part A mixture of the above compounds mixed and dissolved.

Electrolyte D; γ-butyrolactone 100 parts Mono 1,2,3,4-tetramethylimidazolinium phthalate 30 parts p-nitrobenzoic acid 1 part monobutyl phosphate ester 1 part The above compounds were mixed and dissolved. thing.

Electrolyte E; γ-butyrolactone 90 parts Ethylene glycol 10 parts Mono 1,3-dimethyl-2-ethylimidazolinium phthalate 30 parts p-Nitrobenzoic acid 1 part The above compounds are mixed and dissolved.

Electrolyte solution F: γ-butyrolactone 100 parts Mono 1,3,4-trimethyl-2-ethyl imidazolate phthalate 30 parts Boric acid 1 part Mannit 2 parts The above compounds are mixed and dissolved.

Electrolyte G; γ-butyrolactone 100 parts Mono 1,3-dimethyl-2-heptyl phthalate imidazolinium 30 parts Boric acid 1 part Glycerin 2 parts The above compounds are mixed and dissolved.

Electrolyte H: γ-butyrolactone 100 parts Mono 1,3-dimethyl-(-3′heptyl) phthalate imidazolinium 30 parts p-nitrophenol 1 part The above compounds are mixed and dissolved.

Electrolyte solution I: γ-butyrolactone 100 parts Mono 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium phthalate 30 parts p-nitrobenzoic acid 1 part Mix the above compounds, Melted.

Electrolyte solution J: γ-butyrolactone 100 parts Mono-1,3-dimethylimidazolium phthalate 30 parts p-nitrobenzoic acid 1 part A mixture of the above compounds.

Electrolyte solution K: γ-butyrolactone 100 parts Mono-1,3-dimethylbenzimidazole maleate 30 parts p-nitrobenzoic acid 1 part A mixture of the above compounds mixed and dissolved.

Electrolyte L; γ-butyrolactone 100 parts Monotetramethylammonium phthalate 30 parts p-Nitrobenzoic acid 1 part A mixture of the above compounds mixed and dissolved.

The composition of the butyl rubber sealing body used in the examples is as follows. Sealing body A: [Peroxide vulcanization] One obtained by adding 5 parts of dicumyl peroxide as a vulcanizing agent to 100 parts of a butyl rubber polymer composed of a copolymer of isobutylene, isoprene and divinylbenzene.

Seal B: [Sulfur Vulcanization] 100 parts of a butyl rubber polymer composed of a copolymer of isobutylene and isoprene to which 2 parts of sulfur is added as a vulcanizing agent.

(Example 1) A wound type capacitor element constituted by winding a manila fiber separator between an anode foil and a cathode foil was impregnated with an electrolytic solution A, and this capacitor was used. After encapsulating the element together with the sealing body A in a bottomed cylindrical metal case made of aluminum, the opening of the metal case is sealed by curling to obtain an aluminum electrolytic capacitor having a rated voltage of 35 V and a capacitance of 2200 μF. It was

Example 2 The same as Example 1 except that the electrolytic solution B was used as the electrolytic solution. (Example 3) The same procedure was performed as in Example 1 except that the electrolytic solution C was used as the electrolytic solution.

(Example 4) The procedure of Example 1 was repeated except that the electrolytic solution D was used as the electrolytic solution. (Example 5) The same procedure as in Example 1 was performed except that the electrolytic solution E was used as the electrolytic solution.

Example 6 The same as Example 1 except that the electrolytic solution F was used as the electrolytic solution. (Example 7) The same procedure was performed as in Example 1 except that the electrolytic solution G was used as the electrolytic solution.

(Example 8) The same procedure as in Example 1 was carried out except that electrolytic solution H was used as the electrolytic solution. (Example 9) The same procedure as in Example 1 was performed except that the electrolytic solution I was used as the electrolytic solution.

Example 10 The procedure of Example 1 was repeated except that the electrolyte solution J was used as the electrolyte solution. (Example 11) The procedure of Example 1 was repeated except that the electrolytic solution K was used as the electrolytic solution.

(Comparative Example 1) The procedure of Example 1 was repeated except that the electrolytic solution L was used as the electrolytic solution. (Comparative Example 2) The procedure of Example 1 was repeated except that the sealing body B was used as the sealing body.

A reverse voltage of -2.0 V was applied to the aluminum electrolytic capacitors of Examples 1 to 11 and Comparative Examples 1 and 2 to obtain 125
A high temperature load test was performed at 2000C for 2000 hours. The test results are shown in (Table 1) and (Table 2). The number of tests is 20 in each of the examples and comparative examples.

[0042]

[Table 1]

[0043]

[Table 2]

As is clear from (Table 1) and (Table 2), the aluminum electrolytic capacitors having the configurations of Examples 1 to 11 of the present invention are excessive compared with the aluminum electrolytic capacitors of Comparative Examples 1 and 2. It is effective for suppressing liquid leakage when a reverse voltage is applied. That is, an excessive reverse voltage is applied by combining an electrolytic solution using a quaternary salt of a compound having an alkyl-substituted amidine group as an electrolyte and a sealing body formed by adding a peroxide as a vulcanizing agent to a butyl rubber polymer. At times, we were able to obtain a highly reliable aluminum electrolytic capacitor.

[0045]

As described above, the aluminum electrolytic capacitor of the present invention comprises (1) a compound having an alkyl-substituted amidine group of phthalic acid and / or maleic acid in an organic solvent containing γ-butyrolactone as a driving electrolyte. Since an electrolytic solution in which a graded salt is dissolved as an electrolyte is used, even when hydroxide ion is generated by an electrolytic reaction in the electrolytic solution, the hydroxide ion and the N—C—N amidine group are used. As a result, electrolysis products disappear promptly due to the reaction with and decomposition ring-opening, which causes electrolysis which tends to occur when an excessive reverse voltage is applied, as compared with the case where a tetraalkylammonium salt is used as an electrolyte. Since the influence of the reaction can be reduced, the sealing performance of the capacitor can be improved. (2) Since peroxide-vulcanized butyl rubber used for the sealing body has excellent thermal stability, it can be used when an aluminum electrolytic capacitor is used at high temperature for a long time as compared with sulfur-vulcanized butyl rubber. In addition, the sealing force (rubber elasticity) is not significantly reduced, and stable sealing performance can be obtained for a long period of time, whereby leakage of the electrolytic solution from the sealing portion, which tends to occur when the internal pressure rises, can be suppressed.

As described above, due to the synergistic effect of the above items (1) and (2), it is possible to reduce the influence of the electrolysis reaction of the electrolytic solution which tends to occur when a reverse voltage is applied to the capacitor, and to increase the temperature. Even under the condition, the stable sealing force can be maintained and the leakage of the electrolytic solution to the outside can be prevented.

Claims (3)

[Claims] 1. A capacitor element in which an anode foil and a cathode foil are wound together with a separator and impregnated with a driving electrolytic solution, a cylindrical metal case having a bottom for housing the capacitor element, and an opening of the metal case. And a quaternary salt of a compound having an alkyl-substituted amidine group of phthalic acid and / or maleic acid as an electrolyte in an organic solvent containing γ-butyrolactone as the driving electrolytic solution. An aluminum electrolytic capacitor using the electrolytic solution described above and an elastic body obtained by adding a peroxide as a vulcanizing agent to a butyl rubber polymer composed of a copolymer of isobutylene, isoprene and divinylbenzene as the sealing body. 2. An imidazoline compound, an imidazole compound, a benzimidazole compound, an alicyclic pyrimidine in which a quaternary salt of a compound having an alkyl-substituted amidine group is quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group. The aluminum electrolytic capacitor according to claim 1, which is one or more selected from compounds. 3. A quaternary salt of a compound having an alkyl-substituted amidine group is 1-methyl-1,8-diazabicyclo [5,4,0] undecene-7,1-methyl-1,5-.
Diazabicyclo [4,3,0] nonene-5,1,2,3
-Trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,3-dimethyl-2-ethyl-imidazolinium, 1,3,4-trimethyl-2
-Ethylimidazolinium, 1,3-dimethyl-2-heptylimidazolinium, 1,3-dimethyl-2-(-
3'heptyl) imidazolinium, 1,3-dimethyl-
2-dodecylimidazolinium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 1,
The aluminum electrolytic capacitor according to claim 1 or 2, which is one or more selected from 3-dimethylimidazolium and 1,3-dimethylbenzimidazolium.