JP2002359165A - Electrolytic capacitor and electrode foil for electrolytic capacitor used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor having a low ESR characteristic and an electrode foil used therefor. SOLUTION: The capacitor element uses an anode foil set for a porosity of 51% or less after etching and a cathode foil set for a porosity of 44% or less after etching. The capacitor element contains a bond of a water-soluble metal complex with phosphoric acid ions and a solvent containing water as a main component and hence a solid electrolytic capacitor having a low ESR characteristic and an electrode foil used therefor can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrolytic capacitor and an electrode foil for the electrolytic capacitor used therefor.

[0002]

2. Description of the Related Art An aluminum electrolytic capacitor generally has the following configuration. That is, a 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 conversion solution such as an ammonium borate aqueous solution. By doing so, a capacitor element is formed by winding, via a separator, 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 expanded. 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 aluminum electrolytic capacitor.

[0003] The electrolytic solution to be impregnated in the capacitor element of a small, low-pressure aluminum electrolytic capacitor includes:
Adipic acid, with ethylene glycol as the main solvent,
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.

In recent years, electronic information devices have been digitized, and the driving frequency of a microprocessor (MPU), which is the heart of these electronic information devices, has been increasing. As a result, power consumption has increased,
The problem of reliability due to heat generation has become apparent, and as a countermeasure, drive voltage has been reduced. Here, a DC-DC converter called a voltage control module (VRM) is widely used as a circuit for supplying high-precision power to the microprocessor, and its output side capacitor has a series equivalent resistance (VRM) to prevent a voltage drop. Many capacitors with low ESR are used. As a capacitor having this low ESR characteristic, a solid electrolytic capacitor using a solid electrolyte as an electrolyte has been put into practical use, and is widely used as a capacitor suitable for these uses.

However, the drive frequency of the microprocessor has been remarkably increased, and accordingly, the power consumption has been increased. In order to cope with this, it has been required to increase the power supplied from the capacitor to prevent a voltage drop. That is, it is necessary to be able to supply a large amount of electric power in a short time. For this reason, the above-mentioned solid electrolytic capacitor is required to have a larger capacity, a smaller size, a lower voltage, and a lower ESR characteristic than before. Is done.

Therefore, there is an attempt to further reduce the specific resistance of the electrolytic solution by including a large amount of water in the electrolytic solution. However, in such an electrolytic capacitor, the ESR of the capacitor is reduced even though the specific resistance of the electrolyte is low. There is a problem that the effect is not sufficient, and that the leaving property is not good.

[0007]

As described above, there is a limit in reducing the ESR of the capacitor by improving the electrolytic solution for the electrolytic capacitor, and there is a problem that it is difficult to further reduce the ESR.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an electrolytic capacitor having a low ESR and an electrode foil for the electrolytic capacitor used therefor.

[0009]

[Means for Solving the Problems]

The electrolytic capacitor of the present invention has a porosity of 51
% Or less, a capacitor element provided with an anode foil using an etched foil having a concentration of not more than 1% contains a conjugate in which phosphate ions are bonded to a water-soluble metal complex and a solvent mainly composed of water. That is, the etching foil having a porosity of 51% or less can be formed, that is, anodized to obtain the anode foil of the present invention. By setting the porosity of the etching foil to 51% or less as described above, the conductive portion of the anode foil increases, the resistance of the anode foil decreases, and a low specific resistance using a solvent containing water as a main component is obtained. Unprecedented low ESR combined with electrolyte
Although it is possible to realize an electrolytic capacitor having characteristics, if the porosity exceeds 51%, the resistance increases and the desired ESR characteristics cannot be obtained. Further, the porosity is 20
% Or more is preferable because a high capacity can be obtained. Here, the porosity of the etching foil refers to a value calculated by dividing the pore volume of the etching foil by the apparent etching foil volume.

Here, usually, when a solvent containing water as a main component is used for the electrolytic solution, there is a problem that the hydration of the electrode foil is remarkably deteriorated, the characteristics are deteriorated after standing, and the valve is opened. However, in the present invention, since a capacitor in which a phosphate ion is bound to a water-soluble metal complex is contained in the capacitor element, the binder releases phosphate ions into the electrolytic solution, and Since the phosphate ion is held in an appropriate amount to prevent hydration deterioration of the electrode foil, the characteristics after standing are also good.

Further, in the above electrolytic capacitor,
When the foil thickness of the anode foil is 70 μm or more, the resistance of the anode foil is reduced and the ESR is reduced. When the foil thickness is 150 μm or less, downsizing can be achieved. Therefore, the foil thickness is preferably 70 to 150 μm.

Further, the electrolytic capacitor of the present invention comprises a capacitor element having a cathode foil using an etching foil having a porosity of 44% or less, a conjugate comprising phosphate ions bonded to a water-soluble metal complex, Contains a solvent whose main component is water. By setting the porosity of the etching foil to 44% or less in this manner, the conductive portion of the cathode foil increases, the resistance of the anode foil decreases, and a low specific resistance using a solvent containing water as a main component is obtained. Unprecedented low ESR combined with electrolyte
Although it is possible to realize an electrolytic capacitor having characteristics, if the porosity exceeds 44%, the resistance increases and a desired ESR characteristic cannot be obtained. Further, the porosity is 10
% Or more is preferable because a high capacity can be obtained.

Further, in the above solid electrolytic capacitor, when the foil thickness of the cathode foil is in the range of 50 to 100 μm,
This is preferable because ESR can be further reduced and downsizing can be achieved.

Further, in a solid electrolytic capacitor formed by winding the above-mentioned electrode foil, the electrode foil of the capacitor is long and essentially has a large resistance component due to the electrode foil itself.
The effect of reducing the ESR of the entire capacitor is extremely large.

Here, when the metal complex is an aluminum complex, it is possible to form a complex in which phosphate ions are bonded to the water-soluble metal complex in the capacitor element of the aluminum electrolytic capacitor.

The content of water in the solvent is 35 to 10
It is preferable that the content is 0 wt% because the ESR of the electrolytic capacitor is reduced.

[0018]

Embodiments of the present invention will be described more specifically. The aluminum foil is roughened by AC etching in an etching solution composed of hydrochloric acid aqueous solution, etc.
The porosity is set to 51% or less. Further, in order to form a dielectric film, a chemical conversion is performed in a chemical conversion solution composed of a phosphoric acid aqueous solution or the like to prepare an anode foil. By setting the porosity of the etching foil to 51% or less, preferably 43% or less, and more preferably 37% or less, the conductive portion of the anode foil increases and the resistance decreases.
Is reduced. Thus, in the present invention, the porosity is reduced to increase the conductive portion of the electrode foil, and
Since R is reduced, the effect of the present invention is reduced regardless of the state of the etching pit, such as the depth dimension and the area ratio, even when the etching pits on both sides of the etching foil have different depths. There is no. Further, in order to secure the maximum capacity volume efficiency, it is preferable that the porosity is 20% or more, since the etching area increases and a high capacity can be obtained.

Furthermore, when the foil thickness of the anode foil is 70 μm or more, more preferably 90 μm or more, the resistance component of the anode foil is reduced to reduce the ESR, and when it is 150 μm or less, the volume efficiency of the capacitor is improved. Since the size can be reduced, the foil thickness is 70 to 150 μm, and more preferably 90 to 150 μm.
m is preferable.

Further, the aluminum foil is roughened by AC etching or chemical etching in the same manner as the anode foil, and the porosity is adjusted to 44% or less, preferably 35% or less, more preferably 26% or less, to thereby reduce the cathode foil. create. By doing so, the resistance of the cathode foil is reduced, and the ESR of the electrolytic capacitor is reduced. Further, in order to secure the maximum capacity volume efficiency, it is preferable that the porosity is 10% or more, since the etching area increases and a high capacity can be obtained. When the thickness of the cathode foil is in the range of 50 to 100 μm, and more preferably in the range of 70 to 100 μm, ESR can be further reduced and downsizing can be achieved.

Further, it is preferable to form a chemical conversion film of 0.1 to 10 V, preferably 0.3 to 5 V on the cathode foil since ESR is reduced and high-temperature life characteristics are improved.

Further, it is preferable to form a layer made of a metal compound or a metal having low oxidizability such as titanium nitride or titanium on the surface of the cathode foil because the capacitance increases. Here, it is more preferable that a chemical conversion film is formed on the cathode foil, and a layer made of the above-mentioned low oxidizing metal or metal compound is formed on the chemical conversion film.

An electrode lead-out means is connected to each of the above-mentioned anode foil and cathode foil, and is wound via a separator. The effects of the present invention can be obtained using the anode foil and the conventional cathode foil of the present invention described above, and the conventional anode foil and the cathode foil of the present invention. The maximum effect can be obtained by using.

When the electrode lead means is connected to the electrode foil, if the electrode foil having an increased conductive portion of the present invention is used, the contact resistance at the junction between the electrode foil and the electrode lead means decreases, and the ESR of the electrolytic capacitor further increases. Reduce.

Then, the capacitor element thus formed is impregnated with the electrolytic solution using the solvent containing water as a main component of the present invention, housed in a metal case having a low cylindrical shape, and a sealing rubber is provided at the opening end. Is attached and sealed by caulking.

The content of water in the solvent is 35 to 100 wt.
%, The low-temperature characteristics are good at 75 wt% or less.
Preferably, it is 35 to 75 wt%.

Here, a conjugate in which a phosphate ion is bonded to a water-soluble metal complex is contained in the capacitor element. This water-soluble conjugate dissolves a chelating agent, a compound that generates metal ions in an aqueous solution (hereinafter, metal-forming compound) and a compound that generates phosphate ions (hereinafter, phosphoric acid-forming compound) in a solvent. Can be obtained. That is, in this solution, the metal formed in the solution by the chelating agent and the metal-forming compound is chelated to form a water-soluble metal complex. Further, a phosphate ion generated in a solution of the phosphate-generating compound reacts with the water-soluble metal complex to form a conjugate in which phosphate ion is bonded to the water-soluble metal complex (hereinafter, a water-soluble conjugate). . The solvent used here may be any solvent that dissolves the chelating agent, the metal-forming compound and the phosphoric acid-forming compound, and among them, water, ethylene glycol, γ-butyrolactone and the like are preferable.
Then, the water-soluble conjugate thus formed can be added to the electrolytic solution and contained in the capacitor element. Further, the water-soluble composite may be attached to the electrode foil or the separator by coating or the like, and may be contained in the capacitor element.

The capacitor element may be impregnated with an electrolytic solution containing a chelating agent, a metal-forming compound and a phosphoric acid-forming compound, so that the capacitor element contains a water-soluble conjugate. In this electrolytic solution, a water-soluble conjugate is formed by a reaction similar to the reaction in the solvent as described above, and the electrolytic solution is impregnated into the capacitor element so that the water-soluble conjugate is contained in the capacitor element. Can be. In addition, when the electrode foil is aluminum, aluminum ions dissolve from the electrode foil, so that it is possible to form a conjugate in which phosphate ions are bonded to a water-soluble aluminum complex without adding a metal-forming compound. It is suitable.

The water-soluble conjugate thus contained gradually releases phosphate ions into the electrolytic solution, and maintains an appropriate amount of phosphate ions in the electrolytic solution over a long period of time.
And, by the phosphate ions held in this proper amount, the leaving characteristics are favorably maintained.

Examples of the chelating agent include the following. 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- Resorcylic 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.

Examples of the metal-forming compound include a metal and a metal compound. As the metal, a metal which forms a complex with a chelating agent such as aluminum, iron, copper, nickel, manganese, zinc, calcium, magnesium, barium, lead, titanium, niobium, and tantalum can be used. Examples of the metal compound include oxides, hydroxides, chlorides, and metal salts such as sulfates and carbonates.
A compound that generates a metal ion in a solvent can be used. Among them, aluminum is preferred.

Examples of the phosphoric acid-forming compound include a phosphorus compound represented by the general formula (Chemical Formula 1), a salt thereof, a condensate thereof, or a salt of the condensate thereof.

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)

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 compounds 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 linear 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, a condensed phosphoric acid, or a phosphoric acid compound which easily generates a phosphate ion is preferable. 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.

As the solute contained in the electrolytic solution, 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, can be used. 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.

Examples of the anionic component 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.

When at least one of adipic acid or a salt thereof is used as a solute, the ESR is further reduced. The content of adipic acid or its salt in the electrolytic solution,
It is 5 to 23 wt%, preferably 8 to 18 wt%. Above this range, the specific resistance decreases, and below this range, the low-temperature characteristics are good. The content of the other solutes is also about 5 to 23 wt%, preferably 8 to 1 wt% of the whole electrolytic solution.
8 wt%.

In order to further reduce ESR, it is preferable to use formic acid or a salt thereof as a solute. Their content is 3 to 15 wt%, preferably 6 to 12 wt% in the electrolytic solution.
wt%. Below this range, the effect of reducing the ESR is small, and above this range, blistering and valve opening occur due to gas generation. Further, when 3 to 15 wt% of an organic acid or a salt thereof is added, the ESR is reduced. Examples of the organic acid include the above-mentioned adipic acid and glutaric acid. Of these, adipic acid is preferred.

In the electrolytic solution of the present invention, a solvent containing water as a main component is used.
Protic polar solvents, aprotic polar solvents, water, and mixtures thereof can be used. Examples of the protic polar solvent include monohydric alcohols (methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, cyclopentanol, benzyl alcohol, etc.), polyhydric alcohols and oxyalcohol compounds (ethylene glycol, propylene glycol, glycerin) , Methyl cellosolve, ethyl cellosolve, 1,3
-Butanediol, methoxypropylene glycol, etc.)
And so on. Examples of aprotic polar solvents include 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-imidazo] Ridinone (1,3-dimethyl-2
-Imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-di (n-propyl) -2-imidazolidinone, etc., 1,3,4-trialkyl-2-imidazolidinone (1,3,4-trimethyl-2-imidazolidinone and the like)] and the like.

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.

For the purpose of improving the safety of the electrolytic capacitor, a nonionic surfactant, 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, polysaccharides (such as mannitol, sorbite, pentaerythritol), complex compounds of boric acid and polysaccharides, colloidal silica, etc. to the electrolytic solution for electrolytic capacitors 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 of the present invention formed as described above has low ESR characteristics and good standing characteristics.

[0048]

EXAMPLES Specific examples of the electrolytic capacitor of the present invention will be described below. (Example 1) An aluminum foil is roughened by AC etching, and then subjected to a chemical conversion for forming a dielectric oxide film, thereby producing an anode foil of the present invention. Also, the aluminum foil is similarly roughened by AC etching, and a conversion film is formed on the surface to form a cathode foil. The anode foil and the cathode foil are wound around a separator to form a capacitor element.

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. Thus, 10φ × 20L
Was made.

The electrolyte used here was prepared as follows. First, 1 part of diethylenetriaminepentaacetic acid in 10 parts of water,
0.2 parts of aluminum hydroxide and 1.5 parts of ammonium dihydrogen phosphate were added to complete the chelation reaction and the phosphate ion binding reaction to prepare a water-soluble conjugate. Next, the aqueous solution of the water-soluble conjugate was added to an electrolytic solution comprising 50 parts of water, 18 parts of ethylene glycol, 10 parts of ammonium adipate, and 8 parts of ammonium formate to prepare an electrolytic solution of the present invention.

(Example 1-1) In the electrolytic capacitor thus formed, a foil having a thickness of 100 μm and a porosity of 26% after etching was used as an anode foil.
Example 1-1 was used as a cathode foil having a thickness of 85 μm and a porosity of 19% after etching.

Example 1-2 The anode foil had a thickness of 100 μm and the porosity after etching was 46%, and the cathode foil had a thickness of 50 μm and a porosity of 39% after etching. Was used as Example 1-2.

Example 1-3 An electrolytic capacitor was manufactured in the same manner as in Example 1-2 except that a foil having a thickness of 100 μm and a porosity of 33% after etching was used as the anode foil. Was prepared as Example 1-3.

(Example 1-4) A foil having a thickness of 100 µm and a porosity of 52% after etching was used as an anode foil, and a thickness of 75 µm and a porosity of 22% after etching as a cathode foil. Example 1-4 was made using a foil of

(Comparative Example 1) Further, the thickness of the anode foil was 1
A foil having a porosity of 52% after etching, a thickness of 50 μm as a cathode foil, and a porosity of 3 after etching;
Comparative Example 1 was made using a 9% foil.

(Embodiment 2) In the same manner as in Embodiment 1, 10φ
A 12.5 L electrolytic capacitor was prepared. Then, those using the same electrode foils as in Examples 1-1 and 1-3 were referred to as Examples 2-1 and 2-2, and those using the same electrode foil as Comparative Example 1 were referred to as Comparative Example 2. .

The foil resistance of the anode foil and Examples 1-1 to 1-1
Table 1 shows a comparison of the ESR of the electrolytic capacitors according to 4, 2-1, 2-2 and Comparative Examples 1 and 2.

[0058]

[Table 1]

As can be seen from (Table 1), 10φ × 20
In the electrolytic capacitor L, the ESR of Examples 1-2 and 1-3 using the anode foil of the present invention and the Example 1-4 using the cathode foil of the present invention are lower than those of Comparative Example 1. . Further, in the example 1-1 using the anode foil having a porosity of 26% and the cathode foil having a porosity of 19%, the porosity is reduced to 8.7 mΩ, and a low ESR which has not been achieved conventionally is realized. The porosity is 33%.
In Example 1-3 using the anode foil of Example 1-3, the ESR was reduced as compared with Example 1-2 using the anode foil of 46%.

Also, the porosity is reduced from 52% in the comparative example to 26, 33, 46% in the example, so that the foil resistance in the example 1 is from 103 mΩ / m to 34 to 68%.
mΩ / m, and in Example 2, the foil resistance was 213 mΩ / m.
m to 70 to 84 mΩ / m, which indicates that the conductive portion of the electrode foil is increased and the resistance is reduced.

As a comparative example, a capacitor element was formed in the same manner as in Example 1-1, and this capacitor element was impregnated with an electrolytic solution containing a conventional quaternized amidinium salt as a solute to form an electrolytic capacitor. . The used electrolyte was 75 parts of γ-butyrolactone and 25 parts of ethyl dimethyl-imidazolinium phthalate. The resulting ESR is 29 mΩ
This indicates that even if the electrode foil of the present invention is used, the effect of the present invention cannot be obtained unless the embodiment of the present invention containing water as a main component is used.

The same result is obtained with an electrolytic capacitor of 10φ × 12.5 L, and the effect of the present invention is clear.

Then, Examples 1-1 to 1-4, 2-1,
2-2 and a conventional example using the electrode foil of Comparative Example 1 and using the conventional electrolyte solution without adding the water-soluble binder of the present invention.
A high-temperature load and no-load test was performed at 05 ° C. for 1000 hours. The results obtained good values for the examples, but in the conventional example, all valves were opened several hours after the start of the test, and the electrolytic capacitor of the present invention contained a solvent containing water as a main component. Despite this, it was found that the standing characteristics were good.

[0064]

As described above, according to the present invention, it is possible to provide an electrolytic capacitor having an unprecedented low ESR characteristic and a good standing characteristic, and an electrode foil for an electrolytic capacitor used therefor.

Continued on the front page (72) Kazuhiro Saegusa 1-167-1, Higashi-Ome, Ome-shi, Tokyo Inside Nippon Chemi-Con Corporation (72) Inventor Kazuhiro Higuchi 1-1, Sachimachi, Nagai-shi, Yamagata Prefecture (72) Inventor Akihiro Inoue 1-1, Sachimachi, Nagai City, Yamagata Prefecture Marcon Electronics Co., Ltd.

Claims (11)

[Claims] In a capacitor element having an anode foil using an etching foil having a porosity of 51% or less, a conjugate comprising phosphate ions bonded to a water-soluble metal complex and a solvent containing water as a main component. An electrolytic capacitor containing. 2. A capacitor comprising a cathode foil using an etching foil having a porosity of 44% or less, a conjugate in which phosphate ions are bonded to a water-soluble metal complex, and a solvent containing water as a main component. An electrolytic capacitor containing. 3. The electrolytic capacitor according to claim 1, wherein the porosity is 20% or more. 4. The electrolytic capacitor according to claim 2, wherein the porosity is 10% or more. 5. The electrolytic capacitor according to claim 1, wherein the thickness of the anode foil is 70 to 150 μm. 6. The electrolytic capacitor according to claim 2, wherein the thickness of the cathode foil is 50 to 100 μm. 7. The capacitor element according to claim 1, wherein a capacitor element is wound between said anode foil provided with anode extraction means and said cathode foil provided with cathode extraction means via a separator. Electrolytic capacitors. 8. The electrolytic capacitor according to claim 1, wherein the metal complex is an aluminum complex. 9. The content of water in the solvent is 35 to 100 wt.
%. The aluminum electrolytic capacitor according to claim 1, wherein 10. An anode foil for an electrolytic capacitor, wherein an etching foil having a porosity of 51% or less is used. 11. A cathode foil for an electrolytic capacitor, wherein an etching foil having a porosity of 44% or less is used.