JP3366035B2 - Manufacturing method of aluminum electrolytic capacitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum electrolytic capacitor.

[0002]

Conventionally, in an aluminum electrolytic capacitor, a separator such as electrolytic paper is interposed between an anode foil and a cathode foil,
In addition, this separator is impregnated with an electrolytic solution to form a capacitor element. For this reason, when the aluminum electrolytic capacitor is used for a long period of time or at a high temperature, the electrolytic solution permeates through the sealing body and is gradually evaporated, which causes a problem of deterioration in performance. Various methods for improving these problems have been proposed. For example, as the method (1), there are JP-A-63-104317 and JP-A-63-2.
As disclosed in Japanese Patent No. 54717, it has been proposed to use an electrolytic paper in which an organic substituent is introduced into a cellulose fiber by a chemical reaction. Also, as the method of (2),
As shown in Japanese Patent Publication No. 63-54208,
A method of gelling an electrolytic solution has been proposed. In addition to this, in recent years, when overvoltage is applied, there is a demand for an aluminum electrolytic capacitor that is less likely to emit electrolyte solution vapor or leak due to short circuit, ignition, or opening of the outer case valve.To meet this demand, Requires an aluminum electrolytic capacitor that has a high withstand voltage and uses a solid electrolyte.
Therefore, as the method (3), for example, Japanese Patent Laid-Open No. 2-1
As disclosed in Japanese Patent No. 38364, there has been proposed a method of using a polymer solid electrolyte using a cross-linked polymer composed of polyethylene glycol, a trifunctional polyol and polyisocyanate.

[0003]

However, the methods (1) and (2) proposed above are still insufficient to prevent the deterioration of the aluminum electrolytic capacitor, and the method (3) is not sufficient. Among the characteristics of the aluminum electrolytic capacitor, there is a problem that ionic conductivity and tan δ deteriorate.

The present invention solves such a problem, and provides a method for manufacturing an aluminum electrolytic capacitor, which is less deteriorated in performance, has a high withstand voltage, and is excellent in ionic conductivity, equivalent series resistance and tan δ. The purpose is to do.

[0005]

Means for Solving the Problems The method of manufacturing the aluminum electrolytic capacitor of the present invention in order to solve the above problems, fine powder
Hydroxyethyl (alkyl) cellulose as a poor solvent
Dispersion and / or swelling in mixed solvent of poor solvent and good solvent
The resulting solution is applied to at least one of an anode foil, a cathode foil and a separator and dried, and then the anode foil and the cathode.
To wind the foil with a separator in between
The capacitor element is formed from the inside of the case together with the driving electrolyte containing the polyhydric alcohol solvent .
The driving electrolyte solution is gelled by being stored in

[0006]

According to the above method, the capacitor element in which hydroxyethyl (alkyl) cellulose is adhered to at least one of the anode foil, the cathode foil and the separator is brought into contact with the driving electrolyte solution containing the polyhydric alcohol solvent to drive the capacitor element. Since the electrolyte solution for gelation is gelled, volatilization of the polyhydric alcohol solvent at high temperature can be suppressed, and as a result, the aluminum electrolysis with little change in ionic conductivity, equivalent series resistance and tan δ with time. Capacitor can be obtained. Further, the aluminum electrolytic capacitor obtained by the manufacturing method of the present invention can have low reactivity with the aluminum foil and high withstand voltage.

[0007]

EXAMPLES Examples of the present invention will be described below. The basis of the embodiments of the present invention is that at least one of the anode foil, the cathode foil and the separator is hydroxyethyl (alkyl).
An aluminum electrolytic capacitor is manufactured by bringing a capacitor element to which cellulose is attached into contact with a driving electrolytic solution containing a polyhydric alcohol solvent to gel the driving electrolytic solution.

The above-mentioned anode foil and cathode foil may be any aluminum foil usually used for aluminum electrolytic capacitors. The driving electrolytic solution is prepared by dissolving an electrolyte salt in a solvent containing a polyhydric alcohol solvent.

Examples of the polyhydric alcohol solvent include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, glycerin and polyoxyalkylene polyol having a molecular weight of 400 or less, among which ethylene glycol, propylene glycol and these. Is preferably used in combination. Molecular weight is 40
With a polyhydric alcohol solvent of 0 or more, tan δ becomes large, and good capacitor performance cannot be obtained.

If desired, other solvent may be used in combination with this polyhydric alcohol solvent. Water is an example,
Amide-based solvents (N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N-methylpyrrolidinone, etc.), ether-based solvents (methylal,
1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, etc., lactone solvents (γ-butyrolactone, γ-valerolactone, δ)
-Valerolactone, 3-methyl-1,3-oxazolidin-2-one, 3-ethyl-1,3-oxazolidine-
2-one, etc., nitrile solvents (acetonitrile, 3
-Methoxypropionitrile, etc.), furan-based solvents (2,5-dimethoxytetrahydrofuran, etc.), 2-
Examples thereof include imidazolidinones (1,3-dimethyl-2-imidazolidinone, etc.) and pyrrolidones alone or in a mixed solvent. Among these, amide solvents, ether solvents, nitrile solvents, furan solvents Is preferred.
When another solvent is used in combination, the amount is usually 50 parts by weight or less based on 100 parts by weight of the polyhydric alcohol solvent. Good capacitor performance cannot be obtained outside this range.

Examples of the electrolyte salt include ammonium salt,
Included are amine salts and diazabicycloalkene salts. The amine salt comprises a salt of an amine and a salt, and as the amine, a primary amine (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, etc.), 2
Examples include tertiary amines (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.) and tertiary amines (trimethylamine, triethylamine, tripropylamine, triphenylamine, etc.). The quaternary ammonium salt is a salt of a quaternary ammonium and an acid, and as the quaternary ammonium, tetra (alkyl) ammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyl) is used. Diethyl ammonium etc.),
Examples thereof include pyridinium (1-methylpyridinium, 1-ethylpyridinium, 1,3-diethylpyridinium, etc.). The diazabicycloalkene salt is a salt of a diazabicycloalkene and an acid, and the diazabicycloalkene is 1,5-diazabicyclo (4,3,0) nonene-
5,1,8-diazabicyclo (5,4,0) undecene-7 and the like can be mentioned. Examples of acids that form these salts include boric acid, phosphoric acid and carboxylic acids (formic acid, acetic acid, propionic acid, maleic acid, citraconic acid, phthalic acid, adipic acid, azelaic acid, benzoic acid, butyloctanoic acid, formic acid, Decanedicarboxylic acid, etc.) and the like. Among these electrolyte salts, preferred are secondary amines, tertiary amines, amine salts composed of a combination of tetraalkylammonium and carboxylic acid or boric acid, or quaternary ammonium salts. You may use these together.

The separator is composed of a continuous porous substrate. Examples of the communicating porous substrate include a communicating porous substrate made of synthetic polymer (polyolefin, polyester, polyamide, polyimide, fluorinated polyolefin, etc.), cellulose fiber [regenerated cellulose fiber (viscose rayon, cupra rayon, etc.) , Non-wood pulp fibers (manila, red hemp, sisal, esparto grass, etc.), wood pulp fibers (softwood, hardwood, etc.)] and continuous porous substrates made of glass fiber. . Further, a polyethylene porous membrane graft-polymerized with acrylic acid or methacrylic acid or a laminate of a polyamide nonwoven fabric and a polypropylene nonwoven fabric can be used. Among these, the preferred continuous porous substrate is one using polyolefin and cellulose fibers. The pore size of the communicating porous substrate is not limited,
It is usually 0.01 to 1000 μm, preferably 0.1.
The thickness is usually ˜100 μm and the thickness is not limited, but is usually 0.01 to 1 mm, preferably 0.01 to 0.5 mm.

The density of the above-mentioned communicating porous substrate is usually 0.01.
~ 0.9 g / cm ³ . If it is less than this range, the strength of the substrate is insufficient, and if it exceeds this range, problems such as an increase in tan δ of the capacitor occur.

Examples of the hydroxyethyl (alkyl) cellulose include hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxydiethyl cellulose and the like. Of these, hydroxyethyl cellulose and hydroxyethyl methyl cellulose are particularly preferable. Cellulose other than hydroxyethyl (alkyl) cellulose is difficult to gel into an electrolytic solution containing a polyhydric alcohol solvent. The degree of polymerization of hydroxyethyl (alkyl) cellulose depends on the viscosity of a 2% aqueous solution of hydroxyethyl (alkyl) cellulose (25 ° C).
Is 1.0 to 10.0 Pa · s. Good capacitor performance cannot be obtained outside this range.

The content of alkali metal in hydroxyethyl (alkyl) cellulose is usually 1% by weight or less,
It is preferably 0.8% by weight or less. When the content of alkali metal exceeds 1% by weight, the withstand voltage of the capacitor is lowered, and short circuits frequently occur during aging.

Hydroxyethyl (alkyl) cellulose is in powder form, and its particle size is not particularly limited, but it is preferably in the form of fine powder passing through a 42 mesh wire net. Other than finely powdered hydroxyethyl (alkyl) cellulose,
It is difficult to attach it to the anode foil, cathode foil or separator.

The amount of hydroxyethyl (alkyl) cellulose applied to the anode foil, cathode foil or separator is usually 0.01 to 50 parts by weight, preferably 100 parts by weight with respect to 100 parts by weight of the anode foil, cathode foil or separator. It is 0.03 to 40 parts by weight. Good capacitor performance cannot be obtained outside this range.

As a first method of applying hydroxyethyl (alkyl) cellulose to the anode foil, cathode foil or separator and adhering it in the form of particles, as a first method, a solution in which cellulose powder is dispersed in a poor solvent is applied, A method of volatilizing the solvent by heating and / or reducing pressure as necessary, and a second method is to apply a solution obtained by swelling a cellulose powder with a mixed solvent of a poor solvent and a good solvent, and optionally heating and / or reducing pressure to remove the solvent. As a third method of volatilizing, an anode foil, a cathode foil, and a separator are wetted with at least one of a good solvent, a poor solvent, or a driving electrolyte solution, and cellulose powder is sprinkled and adhered thereon, If necessary, a method of volatilizing the solvent by heating and / or reducing pressure may be used.

As the above good solvent, water, methanol,
Examples thereof include dimethylacetamide, examples of the poor solvent include ethylene glycol, dimethylformamide, methylene chloride, methyl acetate, glycerin, and the like, and examples of the electrolytic solution include those described above.

In the method of adhering the hydroxyethyl (alkyl) cellulose to the anode foil, the cathode foil or the separator, the preferred methods are the first method and the second method. The concentration of hydroxyethyl (alkyl) cellulose in the solvent is usually 0.1 to 10% by weight, preferably 0.1.
It is 1 to 5% by weight. If it is out of this range, the workability is significantly reduced.

Next, a method for manufacturing the aluminum electrolytic capacitor of the embodiment of the present invention will be illustrated. Hydroxyethyl (alkyl) cellulose is attached to at least one of a separator, a cathode foil or an etched anode foil, and cut to a specified size, and a lead wire is attached to the anode foil and the cathode foil, and then the anode foil and A cylindrical capacitor element is prepared by interposing a separator between the cathode foil and the cathode foil. Next, the capacitor element impregnated with the driving electrolyte is placed in a case, sealed with a sealing material, and a DC current is applied at high temperature to perform aging. In this aging process, hydroxyethyl (alkyl) is used. Cellulose promotes gelation of the driving electrolyte.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
Hereinafter, parts are parts by weight, and the viscosity is 25% with a 2% aqueous solution viscosity.
It is a value in ° C.

The compositions of the electrolytic solution for driving the aluminum electrolytic capacitor and the hydroxyethyl (alkyl) cellulose used in the examples are as follows. Cellulose A: Finely powdered hydroxyethyl cellulose (viscosity: 4.3 Pa · s, alkali metal content 320 pp
m, transmitted through 42 mesh). Cellulose B: Cellulose A has an alkali metal content of 2
Weight percent. Cellulose C: Cellulose A having a viscosity of 0.3 Pa · s. Cellulose D: hydroxypropyl cellulose (viscosity:
4.3 Pa · s) Electrolyte A: A solution prepared by dissolving 14 parts of diammonium azelate in 100 parts of ethylene glycol. Example 1 Cellulose A (1 part) was swollen with 100 parts of methylene chloride. This was applied to a separator (Manila hemp fiber electrolytic paper, density 0.40 g / cm ³ ) and dried by heating to obtain a separator in which cellulose A was adhered in a particulate form. The adhesion amount of cellulose A was 5% by weight with respect to the separator. (Example 2) The same as Example 1 except that Cellulose B was used instead of Cellulose A in Example 1.
The adhesion amount of cellulose B was 5% by weight with respect to the separator. (Example 3) A separator having cellulose A adhered was obtained in the same manner as in Example 1 except that the steps of coating and heating and drying in Example 1 were repeated several times. The adhesion amount of cellulose A was 10% by weight with respect to the separator. Example 4 An anode foil having cellulose A attached thereto was obtained in the same manner as in Example 1 except that the anode foil was used instead of the separator. The adhesion amount of cellulose A was 5% by weight with respect to the anode foil. (Example 5) A cathode foil to which cellulose A was adhered was obtained in the same manner as in Example 1 except that the cathode foil was used instead of the communicating porous substrate. The adhesion amount of cellulose A was 5% by weight with respect to the cathode foil. (Comparative Example 1) The same procedure as in Example 1 was carried out except that a separator having a density of 1.0 g / cm ³ was used in Example 1.
The adhesion amount of cellulose A was 5% by weight with respect to the separator. (Comparative Example 2) The procedure of Example 1 was repeated except that Cellulose B was used instead of Cellulose A in Example 2. The adhesion amount of cellulose B was 5% by weight with respect to the separator. Comparative Example 3 The procedure of Example 1 was repeated except that Cellulose C was used instead of Cellulose A in Example 1.
The adhesion amount of cellulose C was 5% by weight with respect to the separator. (Comparative Example 4) The same procedure as in Example 1 was carried out except that Cellulose D was used in place of Cellulose A in Example 1.
The adhesion amount of cellulose D was 5% by weight with respect to the separator.

Using the separators or anode foils and cathode foils prepared in Examples 1 to 5 and Comparative Examples 1 to 4, a wound-up type capacitor element having a rated voltage of 35 V and an electrostatic capacity of 1000 μF was prepared. An aluminum electrolytic capacitor was prepared by impregnating the electrolytic solution A, and putting this capacitor element in a case and sealing it with a sealing agent. Apply rated voltage to these, and 2000 at 125 ℃
A high temperature load test of time was performed. The test results (Table 1)
It was shown to. Note that the capacitor characteristics after 125 ° C.-2000 hours are shown in% as the amount of change with respect to each initial characteristic. The number of tests is 10 in each example, and the characteristics are 10
The average value of each capacitor is shown.

[0025]

[Table 1]

As is clear from this (Table 1), in order to obtain a good aluminum electrolytic capacitor, the following is required. (1) The hydroxyethyl (alkyl) cellulose has a high molecular weight (the viscosity of the aqueous solution is high).
(2) The alkali metal content is low. (3) Use hydroxyethyl (alkyl) cellulose. A good aluminum electrolytic capacitor cannot be obtained with hydroxypropyl (alkyl) cellulose. (4) The density of the communicating porous substrate is low.

A voltage of 50 V was applied to an aluminum electrolytic capacitor composed of the separator or the anode foil and the cathode foil prepared in Examples 1 to 5 and Comparative Examples 1 to 4 to obtain 125
An overvoltage test was conducted at 50 ° C. for 50 hours. The test results are shown in (Table 2). The number of tests was set to 10 in each example, and the number of capacitors that caused a short circuit or valve opening after the test is shown in the table.

[0028]

[Table 2]

As is clear from this (Table 2), in order to obtain a good aluminum electrolytic capacitor, the following is required. (1) The hydroxyethyl (alkyl) cellulose has a high molecular weight (the viscosity of the aqueous solution is high). (2)
Low alkali metal content. (3) Use hydroxyethyl (alkyl) cellulose. A good aluminum electrolytic capacitor cannot be obtained with hydroxypropyl (alkyl) cellulose.

[0030]

As is apparent from the above description of the embodiments, according to the method of manufacturing an aluminum electrolytic capacitor of the present invention, the withstand voltage is high, the ionic conductivity, the equivalent series resistance, and the tan δ are excellent, and the temperature is high. Even when used, it is possible to obtain an aluminum electrolytic capacitor with less deterioration of these characteristics, less liquid leakage, less short circuit when overvoltage is applied, and less electrolyte discharge due to valve opening. It has an excellent effect that the manufacturing process of the aluminum electrolytic capacitor can be used as it is.

Front Page Continuation (72) Inventor Tetsuya Samura 1-11, Hitotsubashi-honcho, Higashiyama-ku, Kyoto City, Kyoto Prefecture Sanyo Chemical Industry Co., Ltd. (56) Reference JP-A-4-369816 (JP, A) JP-A-1- 143315 (JP, A) JP-A-63-207114 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01G 9/02 301 H01G 9/035 H01G 9/055 H01G 9/04 H01G 9/00

Claims (5)

(57) [Claims] 1. Finely powdered hydroxyethyl (alkyl)
Disperse cellulose in poor solvent, and / or use good solvent
A solution swollen in a mixed solvent of solvents is applied to at least one of the anode foil, the cathode foil and the separator and dried.
And put a separator between the anode foil and cathode foil
And then winding to form a capacitor element.
A method for manufacturing an aluminum electrolytic capacitor , wherein the capacitor element is housed in a case together with a driving electrolytic solution containing a polyhydric alcohol solvent to cause the driving electrolytic solution to gel. 2. Hydroxyethyl (alkyl) cellulosic
The viscosity (25 ° C) of the aqueous solution when the concentration of soot is 2% is 1.0
The method for manufacturing an aluminum electrolytic capacitor according to claim 1, wherein the method is about 10.0 Pa · s . 3. Hydroxyethyl (alkyl) cellulos
The alkali metal content in the soot is 1% by weight or less.
The method for manufacturing the aluminum electrolytic capacitor according to claim 1 or 2 . 4. The polyhydric alcohol solvent has a molecular weight of 400.
A solvent containing the following polyhydric alcohol solvents:
A method for manufacturing the described aluminum electrolytic capacitor. 5. The separator is composed of a continuous porous substrate.
And the density of the communicating porous substrate is 0.01 to
The method for producing an aluminum electrolytic capacitor according to claim 1, wherein the amount is 0.9 g / cm ³ .