JP2009049070A - Aluminum electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum electrolytic capacitor which is highly reliable and prevents a drive electrolyte from leaking to the outside. <P>SOLUTION: The quaternary salt of 20-180 parts of a compound, which has alkyl substituted amidine group of phthalic acid and/or maleic acid, is dissolved as an electrolyte to an organic solvent of 100 parts containing γ butyrolactone, so as to make an electrolyte. A capacitor element 1 is impregnated with the electrolyte and it is housed in a case 5, and then the case 5 is sealed by a sealing material 6 made of an elastic material which is made by adding peroxides as a curing agent, to a butyl rubber polymer made of copolymer made from isobutylene, isoprene and divinylbenzen, and at least a part of which is 70 degrees (JIS-A) or more in hardness. Thus, the aluminum electrolytic capacitor is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aluminum electrolytic capacitor used in various electronic devices.

  FIG. 1 shows an aluminum electrolytic capacitor conventionally used in various electronic devices. The capacitor element 1 is configured by winding a pair of electrodes 2 (anode foil and cathode foil) made of aluminum foil with a separator 3 interposed therebetween, and each electrode 2 can be soldered to a rod-shaped joint. A lead wire 4 composed of an external lead portion is joined. The capacitor element 1 is impregnated with a driving electrolyte (not shown), and is housed in a case 5 made of bottomed cylindrical aluminum, and the opening of the case 5 is sealed with a sealing body 6. Yes. The outer periphery of the case 5 is covered with an exterior member (not shown).

  As the driving electrolyte, a solution obtained by dissolving an organic acid, an inorganic acid or a salt thereof as an electrolyte in a solvent such as γ-butyrolactone or N, N-dimethylformamide is used. Driving electrolyte using quaternary ammonium salt as electrolyte (for example, see Patent Document 1), driving electrolyte using quaternary ammonium salt of aromatic carboxylic acid as an electrolyte (for example, see Patent Document 2), alkyl-substituted amidine group A driving electrolyte solution (for example, refer to Patent Document 3) using a quaternary salt of a compound having an electrolyte as an electrolyte is known.

As the material of the sealing body 6, sulfur vulcanized ethylene propylene copolymer and butyl rubber are known, and as other materials having excellent thermal stability, resin vulcanized and peroxide vulcanized butyl rubber (for example, patents) Document 4) is known.
Japanese Patent Publication No. 3-6646 Japanese Patent Publication No. 3-8092 Japanese Patent No. 3245604 JP-A 62-276819

  However, conventional aluminum electrolytic capacitors are used for a long time under high temperature and high humidity due to the influence of excess hydroxide ions generated by electrolysis of the driving electrolyte when a voltage is applied to the capacitor element 1. In this case, an increase in the internal pressure of the capacitor and alkali deterioration of the sealing body 6 may occur, and the driving electrolyte may leak from the sealing portion.

  In order to cope with liquid leakage, the above-mentioned peroxide vulcanized or resin vulcanized butyl rubber is used for the sealing body 6, and the sealing body 6 formed of this kind of butyl rubber is generally hardly deteriorated by alkali, In the combination with the driving electrolyte using the quaternary salt of the compound having an alkyl-substituted amidine group as an electrolyte, the leakage of the driving electrolyte caused by excess hydroxide ions is considered to be small, It has been difficult to sufficiently satisfy the reliability of capacitors under high temperature and high humidity.

  An object of the present invention is to solve the above problems, and to provide an aluminum electrolytic capacitor that can further enhance the stability of a sealing portion under high temperature and high humidity and prevent leakage of a driving electrolyte to the outside. It is what.

  In order to solve the above problems, an aluminum electrolytic capacitor of the present invention includes a capacitor element in which an anode foil and a cathode foil each having a lead wire bonded thereto are wound through a separator, and a driving electrolytic impregnated in the capacitor element. A liquid case, a bottomed cylindrical case containing the capacitor element, and a sealing body having a pair of through-holes through which the lead wires penetrate each other and sealing the opening of the case. The liquid is prepared by dissolving 20 to 180 parts of a quaternary salt of a compound having an alkyl-substituted amidine group of phthalic acid and / or maleic acid as an electrolyte with respect to 100 parts of an organic solvent containing γ-butyrolactone. Is obtained by adding a peroxide as a vulcanizing agent to a butyl rubber polymer obtained by copolymerization of isobutylene, isoprene and divinylbenzene, Hardness parts is characterized by being composed of an elastic material it is 70 degrees (JIS-A) or more.

  As a result, the following effects can be obtained. (1) Since the driving electrolyte is composed of a quaternary salt of a compound having an alkyl-substituted amidine group of phthalic acid and / or maleic acid as an electrolyte and dissolved in an organic solvent containing γ-butyrolactone. Even when hydroxide ions are generated by the electrolysis reaction, reaction between the hydroxide ions and the amidine group (N—C—N) and decomposition ring-opening occur, and the electrolytic product disappears quickly. For this reason, compared with the case where a quaternary ammonium salt (for example, a tetraalkylammonium salt) is used as an electrolyte, it is possible to reduce the influence of an electrolysis reaction that easily occurs when a reverse voltage is applied, and the stability of the sealing body. The sealing performance can be improved.

  (2) The above-mentioned butyl rubber vulcanized with peroxide used for the sealing body is superior in thermal stability and alkali resistance, and therefore compared with other vulcanizing methods such as sulfur vulcanized butyl rubber. Thus, even when the capacitor is used at a high temperature for a long time, the rubber elasticity is lowered and the sealing force is reduced little. For this reason, stable sealing performance can be obtained over a long period of time.

  (3) Since the hardness of at least a part of the butyl rubber used for the sealing body is 70 degrees (JIS-A) or more, the sealing force for compressing the lead wire arranged in the through hole of the sealing body can be ensured. For this reason, in addition to the small decrease in the sealing force as described above, a more stable sealing performance can be obtained. When the hardness is less than 70 degrees (JIS-A), the sealing force for compressing the lead wire may not be sufficiently ensured under high temperature and high humidity.

  Due to the synergistic effect of the actions (1) to (3) above, the influence of the electrolysis reaction of the driving electrolyte can be reduced, and a high sealing stress can be achieved not only at high temperature but also at high temperature and high humidity. It becomes possible to maintain stably, and it is possible to prevent leakage of the driving electrolyte that tends to occur when the internal pressure increases.

  The reason why the quaternary salt of the above-mentioned compound having an alkyl-substituted amidine group of phthalic acid and / or maleic acid is used as the electrolyte is because it is electrochemically stable, and is composed of an acid other than phthalic acid and maleic acid. With salt, the amount of gas generated when a voltage is applied is large, and an increase in the internal pressure of the capacitor cannot be sufficiently suppressed. The amount of electrolyte (salt) added is 20 to 180 parts as described above. If it is less than 20 parts, the electric conductivity of the electrolyte is insufficient, and if it exceeds 180 parts, the low temperature characteristics are adversely affected.

  As a quaternary salt of a compound having an alkyl-substituted amidine group, one kind selected from an imidazole compound, a benzimidazole compound, and an alicyclic amidine compound quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group. The above can be used. These compounds have a reaction rate of reaction-decomposition ring-opening between hydroxide ion and amidine group (N—C—N) when hydroxide ion is generated by electrolysis reaction in driving electrolyte. Therefore, the electrolytic product can be quickly lost, and it is effective for preventing liquid leakage under high temperature and high humidity.

  For example, 1-methyl-1,8-diazabicyclo [5,4,0] undecene-7, 1-methyl-1,5-diazabicyclo [4,3,0] nonene-5, 1,2,3-trimethylimidazo Linium, 1,2,3,4-tetramethylimidazolinium, 1,2-dimethyl-3-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, 1,3-dimethylimidazolium, 1,3-dimethylbenzimidazolium can be preferably used. These compounds can increase the conductivity of the driving electrolyte, and are effective in preventing liquid leakage under high temperature and high humidity as described above. It can be configured.

  As the solvent for the driving electrolyte, the above-mentioned γ-butyrolactone is preferable because it is electrochemically stable. For the purpose of improving the low temperature characteristics and the discharge voltage, other organic solvents compatible with γ-butyrolactone may be mixed.

  As other organic solvents, sulfoxide solvents: dimethyl sulfoxide, sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, polyhydric alcohol solvents; ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, glycerin , Polyoxyalkylene polyol, lactone solvent; γ-valerolactone, δ-valerolactone, 3-methyl-1,3-oxazolidine-2-one, 3-ethyl-1,3-oxazolidine-2-one, amide Solvent: N-methylformamide, N, N-dimethylformamide, N-methylacetamide, ether solvent; methylal, 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, nitrile System solvent: acetonitrile, 3 -Methoxypropionitrile, furan solvent; 2,5-dimethoxytetrahydrofuran, 2-imidazolidinone solvent; 1,3-dimethyl-2-imidazolidinone alone or a mixed solvent of two or more.

  The content of the other organic solvent is preferably 200 parts or less, more preferably 160 parts or less with respect to 100 parts of γ-butyrolactone. When the content of the other organic solvent exceeds 200 parts, the electrochemical stability of the driving electrolyte decreases and the internal pressure of the capacitor increases when a voltage is applied, and the driving electrolyte of the present invention is used. A sufficient effect cannot be obtained.

  The moisture content of the capacitor element is usually less than 10% of the weight of the impregnated driving electrolyte. There is a possibility that several percent of water may be mixed from the element member (separator or the like) during assembly. If the water content is 10% or more, the electrolysis reaction is promoted and the internal pressure of the capacitor is increased. Therefore, the water content is basically controlled to 0.5% or less.

Various additives may be mixed in the driving electrolyte as necessary. Examples of additives include phosphorus compounds [phosphoric acid, phosphate esters, etc.], boric acid compounds [boric acid, complex compounds of boric acid and polysaccharides (mannit, sorbit, etc.), boric acid and polyvalent compounds. Complex compounds with alcohol (ethylene glycol, glycerin, etc.)], nitro compounds [o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol, p-nitrophenol, p-nitroacetophenone, etc.]. By mixing these additives, it is possible to improve the restorability of the aluminum oxide film generally formed on the anode foil, thereby suppressing the electrolysis reaction of the driving electrolyte and improving the sealing performance. It becomes possible to raise.
The lead wire may be subjected to anticorrosion treatment, whereby the electrolysis current can be suppressed and the sealing performance can be further improved. The anticorrosion treatment is desirably performed on both the anode and cathode terminal portions, but only one of the treatments may be performed. As an anticorrosion treatment method, anodic oxidation treatment in an aqueous solution, application and sintering treatment of metal alkoxide, and application and sintering treatment of a metal oxide colloid solution (colloid solution of silicon dioxide and titanium dioxide) are easy. Yes, it is preferable.

  The aluminum electrolytic capacitor of the present invention is capable of reducing the influence of the electrolysis reaction of the driving electrolyte, improving the thermal stability and alkali resistance of the sealing body, and ensuring the sealing force (rubber elasticity) These synergistic effects make it possible to maintain high sealing performance stably over a long period of time even under high temperatures and high humidity, and prevent leakage of the driving electrolyte to the outside.

  Embodiments of the present invention will be described below. Since the structure of the aluminum electrolytic capacitor according to the present invention is the same as that of the aluminum electrolytic capacitor described above with reference to FIG. 1, a detailed description will be omitted with the aid of FIG. I will give you a description. These examples do not limit the invention.

(Example 1)
First, the separator 3 interposed between the electrodes 2 and 2 is impregnated with a manila fiber, and this separator 3 is impregnated with a driving electrolyte, so that the rated voltage is 35 V and the capacitance is 2200 μF. The capacitor element 1 was formed, and the capacitor element 1 was sealed in the case 5 together with the sealing body 6, and then curled to seal the opening of the case 5. The driving electrolyte A and the sealing body 6 described later were used as the driving electrolyte and the sealing body 6, respectively.

(Example 2)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolyte B was used.

(Example 3)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolyte C was used.

Example 4
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolyte D was used.

(Example 5)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolyte E was used.

(Example 6)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolyte F was used.

(Example 7)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolyte G was used.

(Comparative Example 1)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolyte H was used.

(Comparative Example 2)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the sealing body B was used.

(Comparative Example 3)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the sealing body C was used.

  Electrolytic solution A for driving; γ-butyrolactone (100 parts), mono 1,2,3,4-tetramethylimidazolinium phthalate (33.3 parts), and p-nitrobenzoic acid (1 part) mixed, Dissolved. All parts indicate parts by weight (hereinafter the same).

  Electrolytic solution B for driving: γ-butyrolactone (100 parts), mono 1,2,3,4-tetramethylimidazolinium phthalate (33.3 parts), monobutyl phosphate ester (1 part), and p-nitrophenol (1 part) mixed and dissolved.

  Driving electrolyte C; γ-butyrolactone (100 parts), mono 1,2,3,4-tetramethylimidazolinium phthalate (33.3 parts), o-nitrobenzoic acid (1 part), and p- Nitroacetophenone (1 part) mixed and dissolved.

  Electrolytic solution D for driving: γ-butyrolactone (100 parts), mono 1,2,3,4-tetramethylimidazolinium phthalate (33.3 parts), m-nitrobenzoic acid (1 part), and monobutyl phosphoric acid Ester (1 part) mixed and dissolved.

  Electrolytic solution E for driving: γ-butyrolactone (100 parts), mono 1,2,3,4-tetramethylimidazolinium phthalate (53.8 parts), m-nitrobenzoic acid (1 part), and monobutyl phosphoric acid Ester (1 part) mixed and dissolved.

  Driving electrolyte F; γ-butyrolactone (100 parts), mono 1,2,3,4-tetramethylimidazolinium phthalate (150 parts), m-nitrobenzoic acid (1 part), and monobutyl phosphate ( 1 part) is mixed and dissolved.

  Electrolytic solution G for driving: γ-butyrolactone (40 parts), sulfolane (60 parts), mono 1,2,3,4-tetramethylimidazolinium phthalate (33.3 parts), m-nitrobenzoic acid (1 Part) and monobutyl phosphate ester (1 part) mixed and dissolved.

  Electrolytic solution H for driving: γ-butyrolactone (100 parts), monotetramethylammonium phthalate (30 parts), and p-nitrobenzoic acid (1 part) mixed and dissolved.

  Sealing body A: 30 parts of butyl rubber polymer made of a copolymer of isobutylene, isoprene and divinylbenzene, 20 parts of carbon, 50 parts of inorganic filler, 5 parts of dicumyl peroxide as a vulcanizing agent And vulcanized.

  The hardness of the sealing body A after molding was measured on the surface portion of the capacitor element side between two through holes that penetrate a pair of lead wires and the surface of the portion in contact with the lead wires inside the through holes. A hardness was 78 degrees and 73 degrees.

  Sealing body B: 5 parts of dicumyl peroxide which is a peroxide as a vulcanizing agent with respect to 40 parts of butyl rubber polymer consisting of a copolymer of isobutylene, isoprene and divinylbenzene, 20 parts of carbon and 40 parts of inorganic filler And vulcanized. However, the temperature at the time of vulcanization molding was set lower than in the case of the sealing body A.

  The hardness of the sealing body B after molding was measured on the surface portion of the capacitor element side between the two through holes that penetrate the pair of lead wires and the surface of the portion in contact with the lead wires inside the through holes. A hardness was 68 degrees and 64 degrees.

  Sealing body C: 2 parts of sulfur as a vulcanizing agent was added to 30 parts of a butyl rubber polymer composed of a copolymer of isobutylene, isoprene and divinylbenzene, 20 parts of carbon, and 50 parts of an inorganic filler, followed by vulcanization molding. thing.

  The hardness of the sealing body C after molding was measured on the surface portion of the capacitor element side between the two through holes that penetrate the pair of lead wires and the surface of the portion in contact with the lead wires inside the through holes. A hardness was 79 degrees and 74 degrees.

  A reverse voltage of -2.0 V was applied to the aluminum electrolytic capacitors of Examples 1 to 7 and Comparative Examples 1 to 3, and a high temperature load test at a temperature of 110 ° C and a temperature of 85 ° C and a relative humidity of 85% for 2000 hours. Went. The number of tests is 20 for each condition. The results are shown in (Table 1).

（表１）から明らかなように、本発明の実施例１〜７のアルミニウム電解コンデンサは、比較例１〜３のアルミニウム電解コンデンサと比較して、電圧印加時の漏液の抑制により有効であり、温度１１０℃、温度８５℃−相対湿度８５％で２０００ｈの高温負荷試験を行った場合においても漏液が観察されない。

As is clear from Table 1, the aluminum electrolytic capacitors of Examples 1 to 7 of the present invention are more effective in suppressing leakage during voltage application than the aluminum electrolytic capacitors of Comparative Examples 1 to 3. No leakage is observed even when a high temperature load test is performed at a temperature of 110 ° C., a temperature of 85 ° C. and a relative humidity of 85% for 2000 hours.

  Accordingly, a driving electrolyte using a quaternary salt of a compound having an alkyl-substituted amidine group as an electrolyte, and a JIS-A hardness of 70 degrees or more formed by adding a peroxide as a vulcanizing agent to a butyl rubber polymer. It can be seen that the combination with the sealing body can realize a highly reliable aluminum electrolytic capacitor even when a voltage is applied under high temperature and high humidity.

  The aluminum electrolytic capacitor of the present invention can prevent leakage even when used under high temperature and high humidity, and can achieve high reliability. Therefore, the aluminum electrolytic capacitor is useful for use in various electronic devices.

Sectional drawing and schematic diagram showing the configuration of conventional and electrolytic aluminum capacitors of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Electrode 3 Separator 4 Lead wire 5 Case 6 Sealing body

Claims (3)

A capacitor element in which an anode foil and a cathode foil each having a lead wire bonded thereto are wound through a separator, a driving electrolyte impregnated in the capacitor element, and a bottomed cylindrical case containing the capacitor element; A sealing body having a pair of through-holes through which the lead wires penetrate each other and sealing the opening of the case,
The driving electrolyte solution is obtained by dissolving 20 to 180 parts of a quaternary salt of a compound having an alkyl-substituted amidine group of phthalic acid and / or maleic acid as an electrolyte with respect to 100 parts of an organic solvent containing γ-butyrolactone. ,
An elastic body in which the sealing body is formed by adding a peroxide as a vulcanizing agent to a butyl rubber polymer obtained by copolymerization of isobutylene, isoprene and divinylbenzene, and at least a part of which has a hardness of 70 degrees (JIS-A) or more. Aluminum electrolytic capacitor composed of   The quaternary salt of the compound having an alkyl-substituted amidine group is at least one selected from an imidazole compound, a benzimidazole compound, and an alicyclic amidine compound quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group. The aluminum electrolytic capacitor according to claim 1.   The quaternary salt of the 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, 1,2-dimethyl-3-ethyl-imidazolinium, 1,3,4-trimethyl- 2-ethylimidazolinium, 1,3-dimethyl-2-heptylimidazolinium, 1,3-dimethyl-2- (3′-heptyl) imidazolinium, 1,3-dimethyl-2-dodecylimidazoli One or more selected from nium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 1,3-dimethylimidazolium, 1,3-dimethylbenzimidazolium The aluminum electrolytic capacitor according to claim 1 or 2.

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