JP2002203754A - Electrolytic capacitor, and electrolyte therefor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor having a good shelf characteristic, and an electrolyte for an electrolytic capacitor used therein and a method of manufacturing the same. SOLUTION: The electrolytic capacitor wound with an electrode foil comprises a capacitor element which is impregnated with an electrolyte added with a chelating agent, a chemical compound which generates phosphoric acid ions in an aqueous solution, and a chemical compound which generates metallic ions in an aqueous solution. Due to this structure, a quantity of phosphoric ions in the electrolyte can be kept at an appropriate one for a long time, and the deterioration of the electrode foil after being on shelf can be suppressed. Consequently, an electrolyte capacitor having a good shelf characteristic, and an electrolyte for an electrolytic capacitor used therein, and a method of manufacturing the same can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor, an electrolytic solution used for the electrolytic capacitor, and a method for producing the same.

[0002]

2. Description of the Related Art An electrolytic capacitor generally has the following configuration. In other words, the high-purity aluminum foil formed in a belt shape is chemically or electrochemically etched to enlarge the surface, and the expanded aluminum foil is subjected to a chemical conversion treatment in a chemical solution such as an ammonium borate aqueous solution. By doing so, a capacitor element is formed by winding an anode foil having an oxide film layer formed on the surface of an aluminum foil and a cathode foil having a high-purity aluminum foil subjected to a surface-expansion treatment via a separator. The capacitor element is impregnated with a driving electrolyte, and is housed in a metal bottomed cylindrical outer case. Further, a sealing body made of elastic rubber is housed at the opening end of the outer case, and the opening end of the outer case is sealed by drawing to form an electrolytic capacitor.

[0003] Conventionally, as an electrolytic solution impregnated in a capacitor element of a small-sized, low-pressure electrolytic capacitor, ethylene glycol as a main solvent, adipic acid,
Known are those in which an ammonium salt such as benzoic acid is used as a solute, and those in which γ-butyrolactone is used as a main solvent and a quaternized cyclic amidinium salt such as phthalic acid or maleic acid is used as a solute.

[0004]

However, when such an electrolytic capacitor is left unattended, the capacitance is reduced, the leakage current characteristic is deteriorated, and the safety valve may be opened. Such a standing characteristic, which is a characteristic after a long period of time with or without a load, has a great influence on the reliability of the electrolytic capacitor.

[0005] Then, when the electrolytic capacitor deteriorated after being left for a long time was analyzed, it was found that the pH of the electrolytic solution was high and the anion component of the solute was attached to the surface of the electrode foil. From this, aluminum on the surface of the electrode foil reacts with the anion component of the solute and adheres to the electrode foil, and further, the aluminum is dissolved to form a hydroxide and the like, and a part of the aluminum reacts with the anion component of the solute. Generates hydrogen gas. It became clear that this reaction was repeated and the pH increased, leading to deterioration of the electrode foil and valve opening.

It is well known that phosphoric acid is effective in preventing such deterioration of the electrode foil, but it is not sufficient. This is because even if this phosphoric acid is added, the added phosphoric acid forms a complex with aluminum in the electrolytic solution and adheres to the electrode foil, and the phosphoric acid disappears from the electrolytic solution. . Further, if the amount is too large, there is a problem that the leakage current increases. However,
As long as the appropriate amount of phosphate ion disappears,
The characteristics of the electrolytic capacitor are kept good. From the above, it is an object of the present invention to provide an electrolytic capacitor having good standing characteristics, an electrolytic solution for the electrolytic capacitor used therefor, and a method for producing the same.

[0007]

An electrolytic capacitor according to the present invention comprises an electrolytic solution containing a chelating agent, a compound that forms phosphate ions in an aqueous solution, and a compound that forms metal ions in an aqueous solution. Is formed by impregnating the capacitor element wound with.

The electrolytic solution for an electrolytic capacitor of the present invention is characterized in that it contains a conjugate in which phosphate ions are bound to a water-soluble metal complex.

The method for producing an electrolytic solution for an electrolytic capacitor according to the present invention comprises the steps of: adding a chelating agent, a compound that forms phosphate ions in an aqueous solution, and a compound that forms metal ions in an aqueous solution. It is characterized in that a conjugate in which a phosphate ion is bound to a water-soluble metal complex is formed.

Further, in the above-mentioned method for producing an electrolytic capacitor and an electrolytic solution for an electrolytic capacitor, the compound that forms phosphate ions in an aqueous solution may be a phosphorus compound represented by the general formula (Chemical Formula 2), a salt thereof, or a salt thereof. It is a condensate or a salt of these condensates.

In the above electrolytic capacitor, electrolytic solution for electrolytic capacitor and method for producing electrolytic solution for electrolytic capacitor, the metal may be iron, copper, nickel, manganese, zinc, calcium, magnesium, barium, lead, titanium, niobium, tantalum. A metal selected from the group consisting of:

[0012]

Embedded image (Wherein R ₁ and R ₂ represent —H, —OH, —R ₃ , —OR
₄ : R ₃ and R ₄ are an alkyl group, an aryl group, a phenyl group, an ether group)

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An electrolytic capacitor of the present invention is formed by winding an electrolytic solution containing a chelating agent, a compound capable of forming phosphate ions in an aqueous solution and a compound capable of forming metal ions in an aqueous solution, on an electrode foil. It is formed by impregnating the turned capacitor element. In this electrolytic solution, the metal formed in the electrolytic solution by the chelating agent and the metal-forming compound is chelated to form a water-soluble metal complex. Further, phosphate ions generated by the phosphate-generating compound in the electrolytic solution react with the water-soluble metal complex to form a conjugate in which phosphate ions are bonded to the water-soluble metal complex.

Usually, after the electrolytic capacitor is manufactured,
It is stored at room temperature for a certain period of time, and then used after being mounted on an electronic device.However, the electrolytic capacitor of the present invention has a phosphate ion contained in the capacitor element bonded immediately after the manufacture, during the period of use. The water-soluble aluminum complex keeps phosphate ions in the electrolytic solution in an appropriate amount.

The following are examples of the chelating agent. That is, citric acid, tartaric acid, gluconic acid, malic acid, lactic acid, glycolic acid, α-hydroxybutyric acid, hydroxymalonic acid, α-methylmalic acid, α-hydroxycarboxylic acids such as dihydroxytartaric acid, γ-resorcylic acid, β- Resorsilic acid, trihydroxybenzoic acid, hydroxyphthalic acid, dihydroxyphthalic acid, phenoltricarboxylic acid, aurintricarboxylic acid, aromatic hydroxycarboxylic acids such as eriochrome cyanine R, sulfocarboxylic acids such as sulfosalicylic acid, guanidines such as dicyandiamide, Saccharides such as galactose and glucose, lignins such as lignosulfonate, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (N
TA), glycol ether diamine tetraacetic acid (GEDT)
A), diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEDTA),
Aminopolycarboxylic acids such as triethylenetetramine hexaacetic acid (TTHA) or salts thereof. And, as these salts, ammonium salts, aluminum salts,
Sodium salts, potassium salts and the like can be used.

As the compound capable of forming a metal ion in an aqueous solution (hereinafter referred to as a metal-forming compound), a metal or a metal compound can be exemplified. Metals include iron, copper, nickel, manganese, zinc, calcium, magnesium,
Metals that form a complex with the chelating agent, such as barium, lead, titanium, niobium, and tantalum, can be used. Further, as the metal compound, oxides, hydroxides, chlorides,
In addition, compounds that generate metal ions in a solvent, such as metal salts such as sulfates and carbonates, can be used.

Then, a compound that generates phosphate ions in an aqueous solution (hereinafter, a phosphate-generating compound) is added. Examples of the phosphoric acid-generating compound include a phosphorus compound represented by the general formula (Formula 2), a salt thereof, a condensate thereof, or a salt of a condensate thereof.

The following are examples of these phosphoric acid-generating compounds. Orthophosphoric acid, phosphorous acid,
Hypophosphorous acid, their salts, and ammonium salts, aluminum salts, sodium salts, calcium salts, and potassium salts. Orthophosphoric acid and its salts decompose in aqueous solution to produce phosphate ions. Phosphorous acid, hypophosphorous acid, and salts thereof are decomposed in an aqueous solution to generate phosphite ions and hypophosphite ions, and then oxidized to phosphate ions.

Phosphoric acid compounds such as ethyl phosphate, diethyl phosphate, butyl phosphate and dibutyl phosphate; and phosphonic acids such as 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylene phosphonic acid and phenylphosphonic acid. Acid compounds and the like. In addition, phosphinic acid compounds such as methylphosphinic acid and butyl phosphinate are exemplified.

Furthermore, the following condensed phosphoric acids or salts thereof can be mentioned. It is a linear condensed phosphoric acid such as pyrophosphoric acid, tripolyphosphoric acid, or tetrapolyphosphoric acid, or a cyclic condensed phosphoric acid such as metaphosphoric acid or hexametaphosphoric acid, or a combination of such chained or cyclic condensed phosphoric acids. . And, as salts of these condensed phosphoric acids, ammonium salts, aluminum salts, sodium salts, calcium salts, potassium salts and the like can be used.

These are also phosphoric acid-generating compounds that generate phosphate ions in an aqueous solution or generate phosphite ions and hypophosphite ions, and then oxidize to phosphate ions.

Among these, orthophosphoric acid or a salt thereof, condensed phosphoric acid, or a phosphoric acid compound which easily generates a phosphate ion is preferred. Further, orthophosphoric acid which generates a lot of phosphate ions relatively quickly with respect to the amount added,
Linear condensed phosphoric acid such as pyrophosphoric acid and tripolyphosphoric acid,
Or a salt thereof is preferred. In addition, other than these compounds, the effect of the present invention can be obtained as long as the substance generates phosphate ions in an aqueous solution.

The solutes contained in the electrolytic solution include ammonium salts, amine salts, quaternary ammonium salts and cyclic amidine compounds which are usually used in electrolytic solutions for electrolytic capacitors and have an anionic component of a conjugate base of an acid. Grade salts. Primary amines (methylamine, ethylamine, propylamine,
Butylamine, ethylenediamine, etc., secondary amines (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.), tertiary amines (trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo (5, 4,0) {undecene} 7 etc.). As the quaternary ammonium constituting the quaternary ammonium salt, tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.), pyridium (1-methylpyridium) , 1-ethylpyridium, 1,3-diethylpyridium, etc.). In addition, examples of the cation constituting the quaternary salt of the cyclic amidine compound include cations obtained by quaternizing the following compounds. That is, the imidazole monocyclic compound (1─
Methylimidazole, 1,2-dimethylimidazole,
Imidazole homologs such as 1,4-dimethyl-2-ethylimidazole and 1-phenylimidazole, oxyalkyl derivatives such as 1-methyl-2-oxymethylimidazole and 1-methyl-2-oxyethylimidazole,
-Methyl-4 (5) -nitroimidazole, nitro and amino derivatives such as 1,2-dimethyl-5 (4) -aminoimidazole, etc., benzimidazole (1-methylbenzimidazole, 1-methyl-2-benzylbenzimidazole) Etc.), compounds having a 2-imidazoline ring (1-methylimidazoline, 1,2-dimethylimidazoline, 1,2,4-trimethylimidazoline, 1,4-
Dimethyl-2-ethylimidazoline, 1-methyl-2-
Phenylimidazoline, etc.), compounds having a tetrahydropyrimidine ring (1-methyl-1,4,5,6-tetrahydropyrimidine, 1,2-dimethyl-1,4,5,6)
-Tetrahydropyrimidine, 1,8-diazabicyclo [5.4.0] undecene-7, 1,5-diazabicyclo [4.3.0] nonene-5, and the like.

The anionic components include adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, formic acid and 1,6-decanedicarboxylic acid ,
Decanedicarboxylic acid such as 5,6-decanedicarboxylic acid,
Octanedicarboxylic acid such as 1,7-octanedicarboxylic acid, azelaic acid, organic acid such as sebacic acid, or
Examples thereof include boric acid, a polyhydric alcohol complex compound of boric acid obtained from boric acid and a polyhydric alcohol, and conjugate bases of inorganic acids such as phosphoric acid, carbonic acid, and silicic acid. Of these, preferred are decanedicarboxylic acid, octanedicarboxylic acid, azelaic acid, sebacic acid, adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, organic carboxylic acids such as formic acid, or boric acid, boric acid. It is a polyhydric alcohol complex compound.

As the solvent, a protic polar solvent, an aprotic polar solvent, water, and a mixture thereof can be used. Protic polar solvents include monohydric alcohols (methanol, ethanol, propanol, butanol, hexanol, cyclohexanol,
Cyclopentanol, benzyl alcohol, etc.), polyhydric alcohol and oxy alcohol compounds (ethylene glycol, propylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, 1,3-butanediol, methoxypropylene glycol, etc.). As aprotic polar solvents, amides (N-methylformamide, N, N-dimethylformamide, N
-Ethylformamide, N, N-dimethylformamide, N-methylacetamide, hexamethylphosphoramide, etc.), lactones (γ-butyrolactone, δ-
Valerolactone, etc.), cyclic amides (N-methyl-2-
Pyrrolidone, etc.), carbonates (ethylene carbonate, propylene carbonate, etc.), nitriles (acetonitrile, etc.), oxides (dimethylsulfoxide, etc.), 2-imidazolidinone [1,3-dialkyl-
2-imidazolidinone (1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-di (n-propyl) -2-imidazolidinone, etc.), 1 , 3,4-trialkyl-2-imidazolidinone (eg, 1,3,4-trimethyl-2-imidazolidinone)] and the like.

Here, usually, when the solvent of the electrolytic solution for the electrolytic capacitor contains water, the deterioration of the electrode foil becomes remarkable,
Also in this case, since an appropriate amount of phosphate ions is released from the water-soluble conjugate, the standing characteristics of the electrolytic capacitor of the present invention are good. Furthermore, even when a solvent containing water as a main component is used, the storage characteristics do not deteriorate, and by using such a solvent, the specific resistance of the electrolytic solution for the electrolytic capacitor can be reduced. Can be reduced in impedance. Here, the content of water in the solvent is 35 to 100 wt%, preferably 35 to 100 wt%.
65 wt%. Above this range, the impedance characteristics are good, and below this range, the low-temperature characteristics are good. In addition, when a solvent containing water as a main component is used, there is no problem such as ignition when the capacitor fails due to nonstandard use such as high voltage use, and the environment resistance is good.

When at least one of adipic acid or a salt thereof is used as a solute, the impedance is further reduced. The content of the adipic acid or salt thereof is 5 to 23 wt% in the electrolytic solution, preferably 8 to 18 w%.
t%. Above this range, the specific resistance decreases, and below this range, the low-temperature characteristics are good. The content of the other solutes is about 5 to 23% by weight, preferably 8 to 18% by weight of the whole electrolyte.

In order to stabilize the life characteristics of the electrolytic capacitor, nitrophenol, nitrobenzoic acid, nitroacetophenone, nitrobenzyl alcohol,
(Nitrophenoxy) ethanol, nitroanisole,
Aromatic nitro compounds such as nitrophenetol, nitrotoluene, dinitrobenzene and the like can be added.

In order to improve the safety of the electrolytic capacitor, a nonionic surfactant, a polyhydric alcohol, ethylene oxide and / or
Alternatively, a polyoxyalkylene polyhydric alcohol ether compound or polyvinyl alcohol obtained by addition polymerization of propylene oxide can also be added.

Further, by adding boric acid, a polysaccharide (such as mannitol, sorbite, pentaerythritol), a complex compound of boric acid and a polysaccharide, and colloidal silica, to the electrolytic solution for an electrolytic capacitor of the present invention. The voltage can be improved.

For the purpose of reducing the leakage current, an oxycarboxylic acid compound or the like can be added.

The electrolytic capacitor containing the electrolytic solution of the present invention has a standing characteristic, that is, a long-term load,
Good characteristics after no-load test.

Hereinafter, the present invention will be described. The electrolytic capacitor of the present invention is formed by impregnating a capacitor element with an electrolytic solution containing a chelating agent, a phosphoric acid-forming compound and a metal-forming compound. In this electrolytic solution, the metal formed in the electrolytic solution by the chelating agent and the metal-forming compound is chelated to form a water-soluble metal complex. Further, the phosphate ion generated by the electrolytic solution of the phosphate-forming compound reacts with the water-soluble metal complex to form a conjugate in which the phosphate ion is bonded to the water-soluble metal complex (hereinafter, a water-soluble conjugate). I do. And this electrolytic solution is impregnated in the capacitor element,
Although the water-soluble binder is contained in the capacitor element, most of the water-soluble binder is contained in the capacitor element in a state of being attached to the electrode foil. This is presumed from the fact that only small amounts of metal ions are detected in the electrolyte. This water-soluble conjugate is considered to be a chelate complex in which a chelating agent and a phosphate ion are coordinated to a metal ion.

[0034] With this water-soluble conjugate, phosphate ions in the electrolytic solution can be maintained in an appropriate amount for a long time. In other words, phosphate ions in the electrolyte are reduced by reacting with aluminum eluted from the electrode foil,
Then the water-soluble conjugate releases phosphate ions,
It acts to keep the phosphate ions in the electrolyte at an appropriate amount. And this proper amount of phosphate ions suppresses the dissolution of aluminum and the production of aluminum hydroxide and the like,
Since the deterioration of the electrode foil is suppressed, the leaving characteristics of the electrolytic capacitor are improved.

That is, if only phosphate ions are added to the electrolytic solution, the phosphate ions react with aluminum and disappear from the electrolytic solution, so that the leaving characteristics deteriorate.
Also, when a large amount is added, the leakage current characteristics are further deteriorated. However, in the electrolytic capacitor of the present invention, an appropriate amount of phosphate ions is present in the electrolytic solution without disappearing even after a long period of time, so that good leaving characteristics can be maintained, and the leakage current characteristics can also be improved. Good without deterioration.

The following experiment has revealed these facts. The electrolytic capacitor of the present invention was disassembled, and the electrolytic solution impregnated in the capacitor element was washed and removed. Thereafter, the capacitor element was impregnated with an electrolytic solution containing no phosphate ions to prepare an electrolytic capacitor. The standing characteristics of the electrolytic capacitor were good. Then, 1 to 10 ppm of phosphoric acid was detected from the electrolytic solution of this electrolytic capacitor, and aluminum was hardly detected. That is, the water-soluble conjugate attached to the electrode foil releases phosphate ions into the electrolyte solution containing no phosphate ions, and after that, by keeping a certain amount of phosphate ions appropriately for a long time, the capacitor is left untreated. The characteristics are improved. In addition, even when the above operation was performed several times for the electrolytic capacitor thus produced, phosphate ions were similarly detected from the electrolytic solution, and the leaving characteristics of the electrolytic capacitor were good. In addition, when the aluminum complex formed in the electrolyte is not water-soluble, that is, when the aluminum complex is hardly soluble or insoluble, it is thought that there is no action to maintain an appropriate amount of phosphate ions in the electrolyte as in the present invention. However, the effects of the present invention cannot be obtained.

Since a certain amount of phosphate ions in the electrolytic solution is consumed by reacting with the electrode foil when preparing the electrolytic capacitor, the amount added at the time of preparing the electrolytic solution is 0.002 mol% by weight.
Further, if added in an amount of 0.04 mol% or more, the initial film dissolution is severe, and the leaving characteristics of the electrolytic capacitor are deteriorated. Therefore, 0.002 to 0.04 mol% by weight is preferable, and 0.003 to 0.04 mol% is more preferable.
0.03 mol% by weight.

The pH of the electrolyte does not rise,
~ 7 (measured by diluting 50 times as an aqueous solution). This is thought to be due to the fact that phosphate ions held in the electrolytic solution suppressed the dissolution of aluminum, and thus suppressed the reaction of the anion component of the electrolyte with aluminum, thereby suppressing the increase in pH. It is.

[0039]

The present invention will be described in detail below with reference to examples. The capacitor element is formed by winding an anode foil and a cathode foil via a separator. The anode electrode foil is obtained by chemically or electrochemically etching an aluminum foil having a purity of 99.9% in an acidic solution and expanding the surface thereof, and then performing a chemical conversion treatment in an aqueous solution of ammonium adipate. Use an oxide film layer. Purity 99.
9% of aluminum foil was etched and a foil subjected to a surface expansion treatment was used.

In the capacitor element configured as described above,
Impregnate the electrolytic solution for driving the aluminum electrolytic capacitor. The capacitor element impregnated with this electrolytic solution is housed in a cylindrical outer case made of aluminum with a bottom, a butyl rubber sealing body is inserted into the open end of the outer case, and the end of the outer case is drawn. To seal the aluminum electrolytic capacitor.

The composition and specific resistance of the electrolytic solution used here are shown in Table 1. The composition is shown in parts. Further, as a conventional example, an electrolytic solution containing 75 parts of γ-butyrolactone and 25 parts of ethyl dimethyl imidazolinium phthalate was used. The specific resistance was 81 Ωcm.

A high-temperature life test of the aluminum electrolytic capacitor constructed as described above was performed. The rating of the aluminum electrolytic capacitor is 6.3 WV-5600 μF. The test conditions are
105 ° C., rated voltage load, no load, 1000 hours. Then, the capacitor after the test was disassembled, and the electrode foil was immersed in a buffer solution having a pH of 7 or more, heated to extract phosphate ions, and the concentration was measured. The measurement lower limit of the phosphate ion concentration is 1 ppm. The results are shown in (Table 2) and (Table 3).

[0043]

[Table 1] (Note) EG: Ethylene glycol AAd: Ammonium adipate TaA: Tannic acid [CAS: 1401-55-4] GluA: Gluconic acid DTPA: Diethylenetriamine hexaacetic acid AlOH: Aluminum hydroxide FeSO: Ferric sulfate NiSO: Nickel sulfate CaCO : Calcium carbonate 2PA: Ammonium dihydrogen phosphate

[0044]

[Table 2] (Note) Cap: capacitance (μF), tan δ: tangent of dielectric loss, LC: leakage current (μA), ΔCap: capacitance change rate (%) Phosphoric acid: phosphoric acid concentration (ppm)

[0045]

[Table 3]

As can be seen from Tables 1 to 3 and the characteristics of the conventional example, the specific resistance of the example is 18 to 68 Ωcm.
And much lower than the conventional 81 Ωcm,
nδ is also 0.042 to 0.054, which is 0.101 of the conventional example.
Lower.

As can be seen from (Table 2) and (Table 3), the phosphoric acid concentration of the Example after 1000 hours has passed is 4 to 12 ppm under each test condition, and the storage characteristics at 105 ° C. are good. Met.

Further, the content of water in the solvent is 40 to 85%.
In Examples 1, 3, and 5, the phosphoric acid concentration was 4 to 12 p.
pm, and the leaving property is also good. Examples 2 to 4 in which the content of ammonium adipate is 10 to 18 parts
Is 6 to 8 ppm, and the leaving property is also good.

On the other hand, Comparative Examples 1 and 2 in which only diammonium hydrogen phosphate was added, respectively,
Although 10,000 ppm and 50 ppm of diammonium hydrogen phosphate were added, the valve was opened, and no phosphate group was detected in the electrolyte at the time of opening the valve. This indicates that the phosphate ions in the electrolyte have disappeared. The initial leakage current of Comparative Example 1 in which 1 part of diammonium hydrogen phosphate was added was high.

[0050]

As described above, according to the present invention, the electrode foil is wound with an electrolytic solution containing a chelating agent, a compound capable of forming phosphate ions in an aqueous solution and a compound capable of forming metal ions in an aqueous solution. Since it is formed by impregnating the turned capacitor element, it is possible to maintain the phosphate ion in the electrolytic solution in an appropriate amount for a long time, and to suppress the deterioration of the electrode foil after being left, so that it has good storage characteristics. , An electrolytic solution for an electrolytic capacitor used therefor, and a method for producing the same.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hisatomi 1-167-1, Higashi-Ome, Ome-shi, Tokyo Nippon Chemi-Con Corporation (72) Inventor Tatsuki Tsuji 1-167, Higashi-Ome, Ome-shi, Tokyo Nippon Chemi-Con Inside the corporation

Claims (8)

[Claims] An electrolytic solution comprising a chelating agent, a compound that forms phosphate ions in an aqueous solution, and a compound that generates metal ions in an aqueous solution is impregnated into a capacitor element wound with an electrode foil. The electrolytic capacitor according to claim 1. 2. The compound which produces phosphate ions in the aqueous solution is a phosphorus compound represented by the general formula (Chemical Formula 1), a salt thereof, a condensate thereof, or a salt of a condensate thereof. The electrolytic capacitor according to 1. 3. The method according to claim 1, wherein the metal ions are iron, copper, nickel, manganese, zinc, calcium, magnesium, barium, lead,
The electrolytic capacitor according to claim 1, wherein the electrolytic capacitor is an ion of a metal selected from titanium, niobium, and tantalum. 4. An electrolytic solution for an electrolytic capacitor comprising a conjugate in which a phosphate ion is bonded to a water-soluble metal complex. 5. The method according to claim 1, wherein the metal complex is iron, copper, nickel, manganese,
The electrolytic solution for an electrolytic capacitor according to claim 4, which is a complex of a metal selected from zinc, calcium, magnesium, barium, lead, titanium, niobium, and tantalum. 6. A bond wherein a phosphate ion is bonded to a water-soluble metal complex by adding a chelating agent, a compound which generates phosphate ions in an aqueous solution, and a compound which generates metal ions in an aqueous solution. A method for producing an electrolytic solution for an electrolytic capacitor which forms a body. 7. The compound that forms phosphate ions in the aqueous solution is a phosphorus compound represented by the general formula (Chemical Formula 1), a salt thereof, a condensate thereof, or a salt of a condensate thereof. 7. The method for producing an electrolytic solution for an electrolytic capacitor according to 6. 8. The method according to claim 1, wherein the metal ions are iron, copper, nickel, manganese, zinc, calcium, magnesium, barium, lead,
The method for producing an electrolytic solution for an electrolytic capacitor according to claim 6, wherein the ion is an ion of a metal selected from titanium, niobium, and tantalum. Embedded image (Wherein R ₁ and R ₂ represent —H, —OH, —R ₃ , —OR
₄ : R ₃ and R ₄ are an alkyl group, an aryl group, a phenyl group, an ether group)