JP2005039245A - Electrolyte for driving and electrolytic capacitor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte for driving that can contribute to high breakdown voltage, high-heat resistance, and a longer operation life of an electrolytic capacitor, and an electrolytic capacitor using the same. <P>SOLUTION: The electrolyte for driving comprises: a solute of a compound containing (formula 1) and (formula 2) which are acquired from menstruum and composition; and one or two kinds of materials selected from phosphoric acid, phosphorous acid, or chlorine thereof and alkyl phosphate. The electrolytic capacitor uses the electrolyte. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a driving electrolyte and an electrolytic capacitor using the same.

  A configuration of a general electrolytic capacitor is shown in FIG. In the figure, a separator 13 is interposed between an anode foil 11 in which a dielectric oxide film is formed by anodic oxidation on a surface of which an effective surface area is expanded by etching the aluminum foil, and a cathode foil 12 in which the aluminum foil is etched. The capacitor element 19 is formed by winding the lead, the anode lead 15 and the cathode lead 16 are connected to the anode foil 11 and the cathode foil 12 of the capacitor element 19 respectively, and the driving electrolyte is connected to the capacitor element 19. 14 is impregnated, the capacitor element 19 is inserted into an aluminum metal case 18, and the opening of the metal case 18 is sealed with a sealing plate 17 to constitute an electrolytic capacitor.

  As the drive electrolyte solution 14, a non-aqueous drive electrolyte solution 14 is known in which an organic carboxylic acid such as azelaic acid, sebacic acid, adipic acid or a salt thereof is dissolved in an ethylene glycol solvent. It has been used for a long time for high pressure because of its relatively good chemical conversion even in an environment of 100 ° C. or higher.

  However, since the non-aqueous driving electrolyte 14 is easily deteriorated by an esterification reaction at a high temperature, butyloctanedioic acid, 5,6-decanedicarboxylic acid, 1,7-octanedicarboxylic acid is used. Dibasic acids having side chains such as acids and their salts are used as electrolytes having an esterification-inhibiting effect.

As prior art document information related to the invention of this application, for example, Patent Documents 1 and 2 are known.
JP-A-2-224217 Japanese Patent Laid-Open No. 3-209810

  In recent years, electrolytic capacitors used for harmonic countermeasure circuits and vehicles have high conductivity, excellent spark voltage at high temperature, long life, and are difficult to break the dielectric oxide film of the electrode. There is a demand for a driving electrolyte solution 14 that is excellent in a film repairing ability (hereinafter referred to as chemical conversion property) for repairing defects when they occur and can suppress a chemical reaction at a high temperature.

  However, when the above-mentioned dibasic acid having a side chain or a salt thereof is used as the solute of the driving electrolyte solution 14, the dibasic acid having the side chain or a salt thereof alone is in the vicinity of one carboxyl group. However, since it has no side chain, the heat resistance at high temperatures is not sufficient, and as it is used for a long time, the carboxyl group of the solute advances the esterification reaction with an alcohol such as ethylene glycol, resulting in a large decrease in conductivity at high temperatures. There is a problem that the performance of the electrolytic capacitor is significantly deteriorated.

  The present invention solves the above-described problems, and has a high conductivity, high chemical conversion property and heat resistance at high temperatures, and a long-life driving electrolytic solution and an electrolytic capacitor using the same. It is intended to provide.

  In order to solve the above problems, the present invention provides a solvent, a solute of a compound containing the general formula (Formula 1) and the general formula (Formula 2) obtained by synthesis, phosphoric acid, phosphorous acid or a salt thereof, and The driving electrolyte solution contains at least one selected from the group consisting of alkyl phosphate esters.

  As described above, according to the present invention, 1,6-decanedicarboxylic acid or 5,6-decanedicarboxylic acid can be obtained by using, as a solute, a compound containing the general formula (Formula 1) and the general formula (Formula 2) obtained by synthesis. Since the electrical conductivity deterioration is small as compared with the acid and the chemical conversion is excellent, the spark voltage can be improved.

  In addition, by containing at least one selected from the group consisting of phosphoric acid, phosphorous acid or salts thereof, and alkyl phosphates, the decrease in conductivity at high temperatures for a long time is reduced, and the chemical conversion is dramatically improved. Thus, a driving electrolyte solution that can contribute to high breakdown voltage, high heat resistance, and long life can be obtained.

  The driving electrolyte of the present invention includes a solvent, a solute of a compound containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) obtained by synthesis, phosphoric acid, phosphorous acid or a salt thereof, and alkylphosphoric acid. It is set as the structure containing at least 1 sort (s) chosen from the group which consists of esters.

  Examples of the solvent include ethylene glycol, propylene glycol, 1,4-butanediol, glycerin, water, polyoxyalkylene polyols, amides, alcohols, ethers, nitriles, furans, sulfolanes, carbonates, and lactones. , Imidazolidinones, pyrrolidones, or a combination of two or more of them can be used as a solvent.

  Specific examples of the above solvents will be described below.

  Examples of the polyoxyalkylene polyols include polyethylene oxide having a molecular weight of 200 or less, polypropylene oxide, polyoxyethylene / oxypropylene glycol, and combinations of two or more thereof.

  Examples of amides include N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N-methylpyrrolidinone and the like.

  Examples of alcohols include methanol and ethanol. Examples of ethers include methylal, 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, ethylene glycol monomethyl ether, and ethylene glycol. Monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol mono Butyl ether, triethylene glycol dimethyl ether And the like.

  Nitriles include acetonitrile, 3-methoxypropionitrile, and furans include 2,5-dimethoxytetrahydrofuran.

  Examples of the sulfolanes include sulfolane, 3-methyl sulfolane, 2,4-dimethyl sulfolane and the like.

  Examples of carbonates include propylene carbonate, ethylene carbonate, diethyl carbonate, styrene carbonate, dimethyl carbonate, and methyl ethyl carbonate.

  Lactones include γ-butyrolactone, γ-valerolactone, δ-valerolactone, 3-methyl-1,3-oxaziridin-2-one, 3-ethyl-1,3-oxazolidine-2-one, and the like.

  Examples of imidazolidinones include 1,3-dimethyl-2-imidazolidinone, and examples of pyrrolidones include polyvinylpyrrolidone.

  Among the above solvents, ethylene glycol, propylene glycol, diethylene glycol, water, lactones, alcohols, carbonates, ethers, nitriles, and furans are preferable.

  The compound containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) obtained by the above synthesis is prepared by, for example, reacting a malonic diester with an alkyl halide in the presence of a base, and further reacting with a dihalogenated alkane. After that, it is obtained by synthesis by saponification, acid decomposition reaction, decarboxylation reaction, the molecular arrangement becomes irregular, and the conductivity can be improved.

  The above general formula (Formula 1) is a dibasic acid, and has an alkyl group at the carbon at the α-position of each of the two carboxylic acids. The general formula (Chemical Formula 2) also has an R = alkyl group at the α-position carbon of the carboxylic acid. These alkyl groups may be the same as or different from each other, or may have a branch. R 'is hydrogen, a methyl group, or an ethyl group. Further, this alkyl group is preferably a lower alkyl group having 1 to 7 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms. Among these, a linear alkyl group having 1 to 4 carbon atoms (such as a methyl group, an ethyl group, a propyl group, or a butyl group) is more preferable.

  N in the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) each independently represents an integer of 0 to 14, preferably n is 1 to 12, more preferably 2 to 10.

  Specific examples of compounds containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) obtained by the above synthesis are shown in Table 1.

  The salt of the compound containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) is an ammonium salt or an amine salt. As the ammonium salt, a quaternary ammonium other than a normal ammonium salt is used. Specific examples thereof include tetramethylammonium salt, trimethylethylammonium salt, dimethyldiethylammonium salt, triethylmethylammonium salt, trimethylbutylammonium salt, dimethylethylpropylammonium salt, dimethylethylbutylammonium salt, dimethyldiethylammonium salt. Propylammonium salt, dimethylpropylbutylammonium salt, dimethyldibutylammonium salt, diethylmethylpropylammonium salt, diethylmethylbutylammonium salt, dipropylmethylethylammonium salt, methyl Tilpropylbutylammonium salt, dibutylmethylethylammonium salt, tripropylmethylammonium salt, dipropylmethylbutylammonium salt, dibutylmethylpropylammonium salt, tributylmethylammonium salt, tetraethylammonium salt, triethylpropylammonium salt, triethylbutylammonium salt, Diethyldipropylammonium salt, diethylpropylbutylammonium salt, diethyldibutylammonium salt, tripropylethylammonium salt, dipropylethylbutylammonium salt, dibutylethylpropylammonium salt, tributylethylammonium salt, tetrapropylammonium salt, tripropylbutylammonium Salt, dipropyldibutylammonium salt, tributylpro Le ammonium salts.

  Examples of amine salts include primary amine salts, secondary amine salts, and tertiary amine salts. Specific examples of the monospherical amine salt include methylamine salt, ethylamine salt, ethylenediamine salt and the like. Specific examples of the secondary amine salt include dimethylamine salt, diethylamine salt, dipropylamine salt, dibutylamine salt, methylethylamine salt, methylpropylamine salt, methylbutylamine salt, ethylpropylamine salt, ethylbutylamine salt, propylbutylamine. Examples include salt. Specific examples of the tertiary amine salt include trimethylamine salt, dimethylethylamine salt, dimethylpropylamine salt, diethylmethylamine salt, diethylbutylamine salt, methylethylpropylamine salt, methylethylbutylamine salt, dipropylmethylamine salt, Methylpropylbutylamine salt, dibutylmethylamine salt, triethylamine salt, diethylpropylamine salt, dipropylethylamine salt, ethylpropylbutylamine salt, dibutylethylamine salt, tripropylamine salt, dipropylbutylamine salt, dibutylpropylamine salt, tributylamine salt Etc.

  The compound containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) is preferably included in a molar ratio of 100: 0 to 55:45, more preferably 90:10 to 55:45, and still more preferably. Is contained in a molar ratio of 80:20 to 55:45, particularly preferably 80:20 to 75:25.

  Specific examples of the phosphoric acid include orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, etc., and salts thereof include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium polyphosphate, pyrophosphoric acid. Ammonium etc. are mentioned. Specific examples of phosphorous acid include hypophosphorous acid, and salts thereof include ammonium hypophosphite, dimethylamine hypophosphite, diethylamine hypophosphite, triethylamine hypophosphite and the like. It is done. In addition, alkyl phosphate esters include monomethyl phosphate ester, dimethyl phosphate ester, monoethyl phosphate ester, diethyl phosphate ester, monopropyl phosphate ester, dipropyl phosphate ester, trimethyl phosphate ester, triethyl phosphate ester, tributyl phosphate. Examples include acid esters, monohexyl phosphate esters, monooctyl phosphate esters, monodecyl phosphate esters, monobutyl phosphate esters, dibutyl phosphate esters, and combinations of two or more of these.

  The driving electrolyte of the present invention can also contain a polyhydric alcohol together with at least one selected from the group consisting of phosphoric acid, phosphorous acid or salts thereof, and alkyl phosphate esters. Examples of the polyhydric alcohol include glycerin, mannitol, sorbit, dulcit, xylit, pentaerythritol, trimethylolpropane, ditrimethylolpropane, neopentyl glycol, dipropylene glycol, butylene glycol, propylene glycol, polyethylene glycol, methyl glycols, multi And the like, which are adsorbed on the surface of the anodic oxide film and cover the defective portion of the oxide film, so that the water resistance can be improved and the spark voltage can be further increased. Among the polyhydric alcohols, mannitol, sorbit, dulcite, xylite, and pentaerythritol are particularly preferable.

  In addition, the driving electrolyte of the present invention contains, for example, a dibasic acid such as azelaic acid that has been conventionally used as a solute of the electrolyte so as not to lose the characteristics of the driving electrolyte. Also good.

  Next, specific examples of the present invention will be described.

(Examples 1-7)
Solvent of the compound containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) shown in (Table 1), and phosphoric acid, phosphorous acid or a salt thereof, and alkyl phosphate esters The driving electrolyte solutions of Examples 1 to 7 to which one or two or more types were added were prepared, and the driving electrolyte solutions of Comparative Examples 1 to 5 were manufactured.

  (Table 2) shows the composition of the driving electrolyte and the electrical conductivity, spark voltage, electrical conductivity before heating test, electrical conductivity, electrical conductivity change rate, and spark voltage after heating test at 110 ° C. in an ampoule for 1000 hours. . The% value in the table indicates an increase or decrease after 1000 hours with the initial value as 100%.

  As is clear from (Table 2), the driving electrolyte solution containing the dibasic acid compound having an alkyl group on both of the α-position carbons of Examples 1 to 7 is more conductive than the driving electrolyte solution of each comparative example. A value with a very small decrease in degree was obtained.

  This is because the α-position alkyl group can suppress the carboxylic acid anhydride and esterification with ethylene glycol as much as possible inside the capacitor, and the α-position carbon alkyl group also prevents amidation by ammonia. It is thought to do.

  On the other hand, the driving electrolyte solution containing ammonium suberate having no alkyl group at the α-position carbon of Comparative Example 1 has a significant decrease in conductivity at 1000 hours and extremely poor electrical stability. The value is shown.

  Moreover, although the electrical conductivity deterioration of the driving electrolyte solution containing ammonium 1,6-decanedicarboxylate of Comparative Example 2 was more severe than that of the driving electrolyte solutions of Examples 1 to 7 of the present invention, the suberin of Comparative Example 1 It was not as much as the conductivity deterioration of the driving electrolyte containing ammonium acid. This is presumably because ammonium 1,6-decanedicarboxylate has one butyl group at the α-position carbon of one carboxyl group.

  However, even when at least one selected from the group consisting of phosphoric acid, phosphorous acid or a salt thereof and alkyl phosphates is added as in the driving electrolytes of Comparative Examples 1 to 5, Examples 1 to 7 Compared with the driving electrolyte, the spark generation voltage is low, and high temperature stability and high breakdown voltage cannot be achieved at the same time.

  Moreover, although the electrical conductivity deterioration of the driving electrolyte solution containing ammonium 5,6-decanedicarboxylate of Comparative Example 4 was also large, this was because the vicinal dicarboxyl group was easily anhydrated and was caused by ethylene glycol. This is because esterification is considered to proceed easily. This ammonium 5,6-decanedicarboxylate has a butyl group on both of the α-position carbons, but the desired electrical characteristics cannot be obtained.

  Next, the electrolytic capacitor having the configuration shown in FIG. 1 described in the above-described conventional technique using the driving electrolytic solutions of Examples 1 to 7 and the driving electrolytic solutions of Comparative Examples 1 to 5 described in (Table 2). (Table 3) shows the result of preparing 20 pieces of each and conducting a 105 ° C. ripple load test. The electrolytic capacitors used here were all rated at 450 V 18 μF.

  As is clear from Table 3, the electrolytic capacitors using the driving electrolytes of Examples 1 to 7 have no short-circuit during aging, and do not cause defects such as short puncture and the like through the life test. There is little change in any of the following characteristics of capacitance change rate, tan δ change, leakage current (LC), and appearance change, and a highly reliable electrolytic capacitor can be obtained.

  On the other hand, the electrolytic capacitors using the driving electrolyte solution of Comparative Example 1 are all short-circuited during aging, and the electrolytic capacitors using the driving electrolyte solutions of Comparative Examples 2 to 5 are short-punctured during the life test. It occurred frequently.

(Examples 8 to 14)
Solutes of compounds containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) shown in (Table 1) in an organic solvent of ethylene glycol, phosphoric acid, phosphorous acid or salts thereof, and alkyl phosphates At least one selected from the group consisting of polyhydric alcohols was added to prepare an electrolytic solution for driving an electrolytic capacitor.

  (Table 4) shows the composition of the driving electrolyte, the conductivity before the heating test, the spark voltage, the electrical conductivity after the heating test at 110 ° C. for 1000 hours in the ampoule, the rate of change in conductivity, and the spark voltage. . The% value in the table indicates an increase or decrease in a predetermined time with the initial value being 100%.

  As is clear from (Table 4), the driving electrolyte solution containing a dibasic acid compound having an alkyl group on both α-position carbons of Examples 8 to 14 is more conductive than the driving electrolyte solutions of the respective comparative examples. A value with a very small decrease in degree was obtained.

  This is because the alkyl group located at the α-position of the compound described in Table 1 in the table can suppress the anhydride formation of carboxylic acid and esterification with ethylene glycol as much as possible inside the capacitor. It is thought that the alkyl group also prevents amidation with ammonia. In particular, those having an alkyl group at the α-positions at both ends of the dicarboxylic acid as in the general formula (Chemical Formula 1) are more effective.

  On the other hand, in the driving electrolyte solution containing ammonium suberate having no alkyl group at the α-position carbon of Comparative Example 6, the electrical conductivity is drastically decreased at 1000 hours and the electrical stability is extremely poor. The value is shown.

  Moreover, although the electrical conductivity deterioration of the drive electrolyte solution containing ammonium 1,6-decanedicarboxylate of Comparative Example 7 was more severe than that of the drive electrolyte solutions of Examples 8 to 14 of the present invention, the suberin of Comparative Example 6 was used. It was not as much as the conductivity deterioration of the driving electrolyte containing ammonium acid. This is presumably because ammonium 1,6-decanedicarboxylate has one butyl group at the α-position carbon of one carboxyl group.

  However, even when polyhydric alcohols are added as in the driving electrolytes of Comparative Examples 6 to 10, the spark generation voltage is low compared to the driving electrolytes of Examples 8 to 14, and the high temperature stability and high Both pressure resistance cannot be achieved.

  Moreover, although the electrical conductivity deterioration of the driving electrolyte solution containing ammonium 5,6-decanedicarboxylate in Comparative Example 9 was also large, this was because the vicinal dicarboxyl group was easily anhydrated and caused by ethylene glycol. This is because esterification is considered to proceed easily. This ammonium 5,6-decanedicarboxylate has both butyl groups at the α-position carbon, but the desired electrical characteristics cannot be obtained.

  Next, an electrolytic capacitor having the configuration shown in FIG. 1 described in the above-described conventional technique using the driving electrolytes of Examples 8 to 14 and the driving electrolytes of Comparative Examples 6 to 10 described in (Table 4). (Table 5) shows the results of preparing a 20 ° C. ripple load test. The electrolytic capacitors used here were all rated at 450 V 18 μF.

  As is clear from Table 5, the electrolytic capacitors using the driving electrolytes of Examples 8 to 14 are free from short-circuits during aging, and do not cause defects such as short punctures and the like through the life test. There is little change in any of the following characteristics of capacitance change rate, tan δ change, leakage current (LC), and appearance change, and a highly reliable electrolytic capacitor can be obtained. This is a group consisting of phosphoric acid, phosphorous acid, salts thereof, and alkyl phosphates in addition to the thermal stability effect of the compounds represented by the general formulas (Chemical Formula 1) and / or (Chemical Formula 2). Capacitor at high temperature load to suppress the reaction with AL electrode foil at high temperature by adding at least one selected from the above, to suppress gas generation, and to promote the repair of defective parts of electrode foil It improves the reliability. Furthermore, by adding polyhydric alcohols, they are adsorbed on the surface of the anodic oxide film and cover the defective part of the oxide film, so that the water resistance of the AL electrode foil can be improved and the spark voltage is further increased. Thus, a more reliable capacitor can be provided.

  In contrast, the electrolytic capacitors using the driving electrolyte of Comparative Example 6 are all short-circuited during aging, and the electrolytic capacitors using the driving electrolyte of Comparative Examples 7 to 10 are short-punctured during the life test. It occurred frequently.

  The driving electrolyte of the present invention and the electrolytic capacitor using the same reduce the decrease in conductivity at high temperature for a long time, suppress gas generation, improve the chemical conversion, and have high withstand voltage, high heat resistance, and long life. The effect is that a stable electrolytic capacitor can be obtained, and its industrial value is great.

Partially cutaway perspective view showing the structure of the electrolytic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Anode foil 12 Cathode foil 13 Separator 14 Driving electrolyte 15 Anode lead 16 Cathode lead 17 Sealing plate 18 Metal case 19 Capacitor element

Claims (6)

At least selected from the group consisting of a solvent, a solute of a compound containing the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) obtained by synthesis, phosphoric acid, phosphorous acid or a salt thereof and an alkyl phosphate A driving electrolyte containing one type.

2. The driving electrolyte solution according to claim 1, wherein the compound of the general formula (Chemical Formula 1) and the general formula (Chemical Formula 2) is an ammonium salt or an amine salt. 2. The driving electrolyte solution according to claim 1, wherein the addition amount of phosphoric acid, phosphorous acid or a salt thereof and an alkyl phosphate ester is 0.1 wt% to 10 wt%. The driving electrolyte solution according to claim 1, comprising a polyhydric alcohol together with at least one selected from the group consisting of phosphoric acid, phosphorous acid, salts thereof, and alkyl phosphate esters. 5. The driving electrolyte solution according to claim 4, wherein the polyhydric alcohol is mannitol, sorbit, dulcite, xylite, or pentaerythritol. The electrolytic capacitor using the electrolyte solution for a drive as described in any one of Claims 1-4.

Images