JPH09115784A - Aluminum electrolytic capacitor and electrolyte for driving it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the withstand voltage of an electrolytic capacitor by adding heteropolyacid to an electrolyte prepared by dissolving the amidinic salt of a carboxylic acid expressed by a specific formula in a non-proton solvent, such as γ-butyrolactone, etc., as a main solute. SOLUTION: An electrolyte for driving aluminum electrolytic capacitor is prepared by adding a heteropolyacid composed of tungstophosphoric acid, tungstosilicic acid, phosphomolybdic acid, silicimolybdic acid, silicitungstomolybdic acid, phophotungstomolybdic acid, or phosphovanadomolybdic acid to an electrolyte prepared by dissolving the amidinic salt of the carboxylic acid expressed by formula I (where, X and R respectively represent the carboxylic acid and a lower alcohol group) as a solute. Therefore, an electrolyte having high electrical conductivity and a high sparking voltage is obtained and, when this electrolyte is used for an electrolytic capacitor, the withstand voltage of the capacitor increases.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrolytic capacitor, and more particularly to an electrolytic solution for driving an aluminum electrolytic capacitor.

[0002]

2. Description of the Related Art Aluminum electrolytic capacitors (hereinafter referred to as
It is called "electrolytic capacitor". ) Is an electrolytic capacitor driving electrolytic solution (hereinafter, referred to as “electrolytic solution”) for a capacitor element in which an anode foil made of aluminum with lead terminals attached and a cathode foil made of aluminum with lead terminals attached are wound around a separator. Liquid)), and this capacitor element is incorporated into an aluminum outer case together with a rubber sealing body, and each lead terminal is pulled out from the through hole of the rubber sealing body to the outside of the electrolytic capacitor. Have.

As the electrolytic solution of the electrolytic capacitor having the above structure, one having a high electric conductivity is selected in consideration of the capacitor characteristics. As a result of various studies, an aprotic solvent such as γ-butyrolactone was used as a main solvent as an electrolytic solution having high electric conductivity, and an amidine salt of a carboxylic acid having the structural formula [1] shown below was dissolved as a main solute. I found what I did.

[0004]

Embedded image

(In the formula, X represents a carboxylic acid, and R represents a lower alkyl group. Examples of the carboxylic acid of X include benzoic acid, phthalic acid, salicylic acid, toluic acid, maleic acid and the like. In the formula, as the lower alkyl group for R, a methyl group, an ethyl group, a propyl group or a butyl group can be exemplified.)

[0006]

An electrolytic solution containing an aprotic solvent such as γ-butyrolactone as a main solvent and an amidine salt of a carboxylic acid as a main solute has a high electric conductivity but a low spark generation voltage. When an electrolytic capacitor is manufactured using an electrolytic solution, there is a drawback that the withstand voltage of the electrolytic capacitor becomes low. Therefore, the electrolytic solution can be used only for a very limited low voltage electrolytic capacitor having a low operating voltage.

[0007]

Means for Solving the Problems The present invention provides an electrolytic solution prepared by dissolving an amidine salt of a carboxylic acid as a main solute in a solvent, particularly an aprotic solvent such as γ-butyrolactone as a main solvent, and an amidine salt of a carboxylic acid. It is intended to improve withstand voltage in an electrolytic capacitor using an electrolytic solution dissolved as a main solute without deteriorating the capacitor characteristics. Specifically, the present invention uses aprotic solvent such as γ-butyrolactone as a solvent and adds a heteropolyacid to an electrolytic solution containing an amidine salt of carboxylic acid as a main solute.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Solvents for the electrolytic solution according to the present invention include γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyrolactone, δ-butyrolactone and γ-butyrolactone.
Aprotic solvents such as valerolactone or δ-valerolactone are preferred and aprotic solvents may be used alone or in combinations of more than one. Among the aprotic solvents, it is particularly preferable to use γ-butyrolactone. The solvent of the electrolytic solution according to the present invention uses an aprotic solvent as a solvent, but methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, benzyl alcohol, amino alcohol, ethylene glycol, propylene glycol, hexylene glycol, Alcohols such as glycerin or hexitol, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl glycol, ethylene glycol phenyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or diethylene glycol diethyl ether, N- Methylformamide, N,
Amides such as N-dimethylformamide, N-ethylformamide or N, N-diethylformamide, N
-Acetamides such as -methylacetamide, N, N-dimethylacetamide, N-ethylacetamide or N, N-diethylacetamide, propionamides such as N, N-dimethylpropionamide, hexamethylphosphorylamides, N-methyl- Oxazolidinones such as 2-oxazolidinone or 3,5-dimethyl-2-oxazolidinone, acetonitrile, nitriles such as acrylonitrile, aromatic solvents such as toluene and xylene, paraffin solvents such as normal paraffin and isoparaffin, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidine or N
-Methyl pioridone or the like may be mixed with an aprotic solvent. In the present invention, the mixed solvent is preferably a solvent in which γ-butyrolactone and ethylene glycol are mixed.

The amidine salt of carboxylic acid which is the main solute of the electrolytic solution according to the present invention includes amidine salt of phthalic acid, amidine salt of maleic acid, amidine salt of benzoic acid, amidine salt of salicylic acid or amidine salt of toluic acid. It is preferably used. Specific examples thereof include acetamidine phthalate, acetamidine maleate, acetamidine benzoate, acetamidine salicylate and acetamidine toluate. Particularly, acetamidine phthalate or acetamidine maleate is preferable.

Examples of the heteropoly acid which is the additive of the electrolytic solution according to the present invention include phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, silicotungstomolybdic acid, phosphotungstomolybdic acid or phosphovanadomolybdic acid. Can be mentioned. The amount of the heteropoly acid added to the electrolytic solution is 0.5% by weight to 10% by weight.
It is preferred that If the amount of the heteropolyacid added to the electrolytic solution is less than 0.5% by weight, the spark generation voltage of the electrolytic solution cannot be improved. When the amount of the heteropolyacid added to the electrolytic solution exceeds 10% by weight, the heteropolyacid may be precipitated in the electrolytic solution, which is not preferable.

In the electrolytic solution according to the present invention, water may be added in an amount of 5% by weight or less in order to improve the chemical conversion property and electric conductivity of the electrolytic solution. Addition of water in excess of 5% by weight corrodes the aluminum foil, which is not preferable.

[0012]

EXAMPLES Hereinafter, composition examples of the electrolytic solution according to the present invention will be described together with comparative examples. In the electrolytic solution of each example, 40
Since the electrical conductivity at μC (μS / cm) and the spark generation voltage (V) at 85 ° C were measured, the respective values are also shown.

<Example 1> o-Acetamidine phthalate 20% by weight γ-butyrolactone 65% by weight Ethylene glycol 10% by weight Phosphotungstic acid 5% by weight The conductivity was 9300 μS / cm and the spark generation voltage was 75V.

<Example 2> o-Acetamidine phthalate 20% by weight γ-butyrolactone 65% by weight Ethylene glycol 10% by weight Silicotungstic acid 5% by weight The conductivity was 9450 μS / cm and the spark generation voltage was 72V.

<Comparative Example 1> o-Acetamidine phthalate 20% by weight γ-butyrolactone 70% by weight Ethylene glycol 10% by weight The conductivity was 9500 μS / cm and the spark generation voltage was 52V.

Example 3 Acetamidine maleate 20% by weight γ-butyrolactone 75% by weight Tungstosilicic acid 5% by weight Conductivity 18000 μS / cm, spark generation voltage 49 V
Met.

Example 4 Acetamidine maleate 20% by weight γ-butyrolactone 75% by weight Phosphomolybdic acid 5% by weight Conductivity 18500 μS / cm, spark generation voltage 52V
Met.

Comparative Example 2 Acetamidine maleate 20% by weight γ-butyrolactone 80% by weight Conductivity is 19000 μS / cm, spark generation voltage is 36V.
Met.

Example 5 Acetamidine phthalate 25% by weight γ-butyrolactone 70% by weight Tungstosilicic acid 5% by weight Conductivity 14600 μS / cm, spark generation voltage 62V
Met.

Example 6 Acetamidine phthalate 25% by weight γ-butyrolactone 70% by weight Phosphotungstic acid 5% by weight Conductivity 14500 μS / cm, spark generation voltage 60 V
Met.

Comparative Example 3 Acetamidine phthalate 25% by weight γ-butyrolactone 75% by weight Conductivity is 15000 μS / cm, spark generation voltage is 39V.
Met.

Example 1 and Example 2 and Comparative Example 1, Example 3 and Example 4 and Comparative Example 2, and Example 5 and Example 6 and Comparative Example 3, spark generation voltages of these electrolytes, respectively. By comparison, it can be seen that the example has a significantly higher spark generation voltage and is superior to the comparative example. When the electric conductivity of the electrolytic solution is compared between Example 1 and Example 2 and Comparative Example 1, and between Example 3 and Example 4 and Comparative Example 2, there is a difference in electric conductivity between the Example and the Comparative Example. No, it turns out to be equivalent.

Next, using the electrolytic solution of Example 1, the electrolytic solution of Example 2 and the electrolytic solution of Comparative Example 1, a rated voltage of 63 V,
100 electrolytic capacitors with a capacitance of 470 μF each
This was produced. Furthermore, a rated voltage of 35 V was obtained by using the electrolytic solution of Example 3, the electrolytic solution of Example 4, the electrolytic solution of Example 5 and the electrolytic solution of Example 6 and the electrolytic solution of Comparative example 2 and the electrolytic solution of Comparative example 3. , 100 electrolytic capacitors each having a capacitance of 2700 μF were manufactured. The capacitance (μF), tangent of loss angle (tan δ) and leakage current (μA) of the produced electrolytic capacitor were measured. Table 1 shows the average value of the measurements.

[0024]

[Table 1]

As can be seen from Table 1, the electrolytic solution of Example 1 and the electrolytic solution of Example 2 had a rated voltage of 63 V and a capacitance of 470.
Although a μF electrolytic capacitor could be manufactured, the electrolytic solution of Comparative Example 1 could not manufacture an electrolytic capacitor having a rated voltage of 63 V and a capacitance of 470 μF because the spark generation voltage was insufficient with respect to the rated voltage. With the electrolytic solution of Example 3, the electrolytic solution of Example 4, the electrolytic solution of Example 5 and the electrolytic solution of Example 6, an electrolytic capacitor having a rated voltage of 35 V and a capacitance of 2700 μF could be manufactured, but the electrolytic solution of Comparative Example 2 With the liquid and the electrolyte of Comparative Example 3, the spark generation voltage was insufficient with respect to the surge voltage, and the rated voltage 3
An electrolytic capacitor with 5 V and a capacitance of 2700 μF could not be manufactured.

[0026]

From the above, the electrolytic solution of the present invention in which an amidine salt of a carboxylic acid is dissolved as a main solute in a solvent and a heteropolyacid is added is compared with a solvent in which an amidine salt of a carboxylic acid is dissolved as a main solute. It is possible to obtain a spark generation voltage higher than that of the electrolytic solution of the comparative example while having an electric conductivity equivalent to that of the electrolytic solution of the example. As a result, when the electrolytic solution of the present invention is used, an electrolytic capacitor having a withstand voltage superior to that of the electrolytic capacitor using the electrolytic solution of the comparative example can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideo Shimizu 2-2-1 Tsujido Shinmachi, Fujisawa City, Kanagawa Elna Co., Ltd.

Claims (8)

[Claims] 1. A solvate containing an amidine salt of a carboxylic acid represented by the following structural formula [1] as a solute, and phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, silicotungstomolybdic acid,
An electrolytic solution for driving an aluminum electrolytic capacitor, to which a heteropolyacid such as phosphotungstomolybdic acid or phosphovanadomolybdic acid is added. Embedded image (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.) 2. An aprotic solvent as a main solvent, an amidine salt of a carboxylic acid represented by the following structural formula [1] as a solute, and phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, An electrolytic solution for driving an aluminum electrolytic capacitor, characterized in that a heteropoly acid such as silicate tungsten molybdic acid, phosphorus tungsten molybdic acid or phosphovanado molybdic acid is added. Embedded image (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.) 3. A main solvent is γ-butyrolactone, and an amidine salt of a carboxylic acid represented by the following structural formula [1] is dissolved as a solute and at the same time phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicobidenic acid, and silicotan. An electrolytic solution for driving an aluminum electrolytic capacitor, wherein a heteropolyacid such as gustmolybdic acid, phosphotungstomolybdic acid or phosphovanadomolybdic acid is added. Embedded image (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.) 4. A solubilized amidine salt of a carboxylic acid represented by the following structural formula [1] as a solute in a solvent in which γ-butyrolactone and ethylene glycol are mixed together, and phosphotungstic acid, silicotungstic acid, phosphomolybdic acid,
An electrolytic solution for driving an aluminum electrolytic capacitor, characterized in that a heteropoly acid such as silicate molybdenum acid, silicate tungstomolybdic acid, phosphorus tungstomolybdic acid or phosphovanadomolybdic acid is added. Embedded image (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.) 5. A solubilized amidine salt of a carboxylic acid represented by the following structural formula [1] as a solute is dissolved in a solvent, and phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicohumidic acid, silicotungstomolybdic acid, and phosphotungsto are dissolved. An aluminum electrolytic capacitor characterized by using an electrolytic solution for driving an aluminum electrolytic capacitor containing a heteropolyacid such as molybdic acid or phosphovanadomolybdic acid or phosphovanadomolybdic acid. Embedded image (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.) 6. An aprotic solvent as a main solvent, and an amidine salt of a carboxylic acid represented by the following structural formula [1] is dissolved as a solute, and at the same time, phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicobudonic acid, and silicic acid. An aluminum electrolytic capacitor characterized by using an electrolytic solution for driving an aluminum electrolytic capacitor containing a heteropolyacid such as gustomolybdic acid, phosphotungstomolybdic acid or phosphovanadomolybdic acid. [Chemical 6] (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.) 7. A main solvent is γ-butyrolactone, and an amidine salt of a carboxylic acid represented by the following structural formula [1] is dissolved as a solute, and at the same time phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomobdenic acid, and silicotan. Gustomolybdic acid, phosphorus tungstomolybdic acid,
An aluminum electrolytic capacitor characterized by using an electrolytic solution for driving an aluminum electrolytic capacitor to which a heteropoly acid such as silicate tungsten molybdic acid, phosphorus tungsten molybdic acid or phosphovanado molybdic acid is added. Embedded image (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.) 8. A solubilized amidine salt of carboxylic acid represented by the following structural formula [1] as a solute and a phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and a solvent in which γ-butyrolactone and ethylene glycol are mixed. An aluminum electrolytic capacitor characterized by using an electrolytic solution for driving an aluminum electrolytic capacitor to which a heteropolyacid such as silicate molybdenic acid, silicate tungstomolybdic acid, phosphorus tungstomolybdic acid or phosphovanadomolybdic acid is added. Embedded image (In the formula, X represents a carboxylic acid and R represents a lower alkyl group.)