JPH04313210A - Electrolytic solution for electrolytic-capacitor driving use - Google Patents

Abstract

PURPOSE:To provide an electrolytic solution, for electrolytic-capacitor driving use, which can make a sparking voltage sufficiently high without lowering its specific conductivity. CONSTITUTION:An electrolytic solution for electrolytic-capacitor driving use is constituted in the following manner: an ultrafine-particle inorganic compound is dispersed in a solvent composed mainly of gamma-butylolactone; and either or hexitol boric acid or both of them are added and dissolved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for driving an electrolytic capacitor, and more specifically, to an electrolytic solution for driving an aluminum electrolytic capacitor.

0002

2. Description of the Related Art As a conventional electrolytic solution for driving an electrolytic capacitor, an electrolytic solution in which boric acid or a salt thereof is dissolved in ethylene glycol is used. However, this type of electrolytic solution has a drawback in that its specific conductivity is low and its impedance characteristics are significantly reduced, especially at low temperatures. Therefore, as seen in JP-A No. 61-70711, there are examples using γ-butyrolactone as a solvent and triethylamine salt of phthalic acid, and JP-A No. 62-145715.
As seen in the above publication, there are examples of using quaternary ammonium salts of aromatic carboxylic acids.

0003

[Problem to be Solved by the Invention] However, when trying to obtain high specific conductivity using the electrolyte used in these electrolytes, there is a problem that a sufficiently high spark generation voltage cannot be obtained. . In addition, as an electrolytic solution with improved withstand voltage characteristics without impairing conductivity, a driving electrolytic solution prepared by adding an inorganic acid or a polysaccharide to a quaternary ammonium salt of an aromatic carboxylic acid was disclosed in JP-A-63- It is disclosed in Japanese Patent No. 248113, but in this, the rated voltage is 100V.
There was a problem in that a high spark generation voltage that could be used for the above electrolytic capacitors could not be obtained.

The present invention solves the above-mentioned conventional problems, and aims to provide an electrolytic solution for driving an electrolytic capacitor that can sufficiently increase the spark generation voltage without reducing the specific conductivity. It is something.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the electrolytic solution for driving an electrolytic capacitor of the present invention has an ultrafine particle inorganic compound dispersed in a solvent mainly composed of γ-butyrolactone, and hexites and boron. Either or both of the acids are added and dissolved.

[0006]

[Function] The electrolytic solution for driving an electrolytic capacitor of the present invention described above is prepared by dispersing an ultrafine inorganic compound in a solvent mainly composed of γ-butyrolactone, and adding one or both of hexites and boric acid. It is dissolved,
Since the ultrafine inorganic compound is charged in the electrolytic solution and becomes colloidal, it can be uniformly dispersed in the electrolytic solution. In addition, when an oxide film is formed, the ultrafine inorganic compound adsorbs and aggregates to fill in the defective parts of the oxide film, making it possible to produce an oxide film with fewer defects.This makes it possible to increase the spark generation voltage, and In addition to this, by adding one or both of hexites and boric acid, the surface of the anodic oxide film is covered with the hexites, thereby making it possible to further increase the spark generation voltage.

[0007]

[Examples] Examples of the present invention will be described below.

The electrolytic solution for driving an electrolytic capacitor of the present invention is basically made by dispersing an ultrafine inorganic compound in a solvent mainly composed of γ-butyrolactone, and adding one or both of hexites and boric acid. The dissolved ultrafine inorganic compound is preferably a metal oxide, metal nitride, or metal carbide. Usually, ultrafine inorganic compounds are electrically charged in an electrolytic solution, so they become colloidal and dispersed, but some particles are difficult to disperse depending on the pH of the solution and the type of inorganic compound. In that case, dispersion can be achieved by using an appropriate surfactant or performing surface treatment.

Examples of metal oxides include basic oxides (TiO2, ZrO2, Fe2O3, HfO2, Y2
O3, Al2O3, Ga2O3, In2O3, SnO2
, Bi2O3, etc.); acidic oxides (SiO2, Nb2O5
, Ta2O5, WO3, GeO2, SeO2, Sb2O
3, TeO2, etc.); composite oxide (SiO2-Al2O3
, SiO2-MgO, SiO2-CaO, SiO2-S
rO, SiO2-BaO, SiO2-ZrO2, etc.). Among these, preferred are SiO2 and TiO2 alone or in combination.

Examples of metal nitrides include TiN, S
i3N2, AlN, TaN, Zr3N4, NbN, Zr
An example is N. Among these, preferred is Ti
It is one type or a mixture of two or more types of N, Si3N2, AlN, and Zr3N4.

[0011] As the metal carbide, SiC, TiC, M
Examples include o2C and WC. Preferred among these are SiC and TiC alone or in combination.

[0012] Furthermore, since similar effects can be obtained even when the ultrafine particle inorganic compound is dispersed in other solvents, examples of the solvent of the present invention include γ-butyrolactone alone or a mixture with other solvents. . Examples of solvents that can be mixed include alcohols {monohydric alcohols (methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, benzyl alcohol, amino alcohol, etc.); dihydric alcohols (ethylene glycol, propylene glycol, diethylene glycol, hexylene glycol, etc.); trihydric alcohol (
glycerin, etc.), hexitol, etc.}, ethers {monoethers (ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol phenyl ether, etc.); diethers (ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.)}, amides {formamides (N-methylformamide, N,N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, etc.); acetamides (N-methylacetamide, N,N-dimethylformamide, etc.); -dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide, etc.)
; Propionamides (N,N-dimethylpropionamide, etc.); Hexamethylphosphorylamide, etc.}, Oxazolidinones (N-methyl-2-oxazolidinone, 3
, 5-dimethyl-2-oxolidinone, etc.), lactones (α-acetyl-γ-butyrolactone, β-butyron lactone, γ-valerolactone, δ-valerolactone, etc.)
, Nitriles (acetonitrile, acrylonitrile, etc.)
, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone, aromatic solvents (toluene, xylene, etc.), paraffinic solvents (normal paraffin, isoparaffin, etc.), and two or more of these Mixtures may be mentioned.

The solute may be an inorganic acid, an organic acid or a salt thereof, such as boric acid, azelaic acid, adipic acid, glutaric acid, phthalic acid, maleic acid, benzoic acid, butyloctanedioic acid or a salt thereof. One or more of these may be mentioned as the main solute. As the above acid salts, ammonium salts, amine salts, quaternary ammonium salts, etc. can be used. Among these solutes, preferred are the quaternary ammonium salts of phthalic acid.

The amount of the ultrafine inorganic compound to be dispersed is 0.1 to 30%, preferably 1 to 30%, based on the electrolyte.
It is 20%. This has no effect below 0.1%,
Moreover, if it exceeds 30%, agglomeration tends to occur.

[0015] Furthermore, the smaller the particle size, the better;
Although it can be dispersed from about μm, in this case, it is preferable that it is 100 nm or less.

Although hexites and boric acid may be added singly, it is preferable to add both of them because of better solubility.

Next, specific embodiments of the present invention will be explained. (Table 1) shows the specific electrolyte compositions of Conventional Examples 1, 2, and 34 and Examples 1, 2, 3, and 4 of the present invention, and the specific conductivity and spark generation voltage at 30°C in each of these examples. This shows the measurement results.

Ultrafine anhydrous silica, which is a metal oxide constituting the ultrafine inorganic compound used in Examples 1, 3, and 4 of the present invention, was purified by chlorinating ferrosilicon to form silicon tetrachloride. The resulting product was hydrolyzed in an oxygen and hydrogen flame and decomposed with mechanical stirring. In addition, ultrafine titanium oxide, which is a metal oxide constituting the ultrafine inorganic compound used in Example 2 of the present invention, is obtained by mechanically oxidizing titanium tetrachloride vapor in the gas phase with oxygen. Stir to disperse.

[0019]

[Table 1]

As is clear from this (Table 1), Examples 1, 3, and 4 of the present invention in which silicon oxide, which is a metal oxide constituting the ultrafine particle inorganic compound, is dispersed, and Examples 1, 3, and 4 of the present invention in which silicon oxide, which is a metal oxide constituting the ultrafine particle inorganic compound, are dispersed, and the present invention in which titanium oxide is dispersed. The electrolytic solution of Example 2 of the invention is the same as that of Conventional Examples 1 and 2.
, 3 and 4, the spark generation voltage can be increased without reducing the specific conductivity.

(Table 2) and (Table 3) show the conventional examples 3 and 4 and the embodiments 2 and 3 of the present invention among the electrolytes shown in (Table 1).
This figure shows the results of a high-temperature load test conducted at a temperature of 105° C. for 2000 hours on 20 electrolytic capacitors each using electrolytes of 4 and 4. Among these electrolytic capacitors, the electrolytic capacitors using the electrolytes of Conventional Example 3 and Embodiment 2 of the present invention have a rating of 100V100μF, and the aging of the products was performed by applying a voltage of 125V for 1 hour at 105°C. Ta. Also, conventional example 4 and embodiments 3 and 4 of the present invention.
The rating of an electrolytic capacitor using the electrolyte is 160V3
At 30 μF, the product will age at 105°C for 20
The test was carried out by applying a voltage of 0V for 1 hour.

[0022]

[Table 2]

[0023]

[Table 3]

As is clear from (Table 2) and (Table 3),
The electrolytic capacitors using the electrolytes of Examples 2, 3, and 4 of the present invention can lower tan δ and have high conductivity compared to the electrolytic capacitors using the electrolytes of Conventional Examples 3 and 4. This allows the electrolyte to be used in a high voltage range and also eliminates the occurrence of short circuits.

[0025]

As described above, the electrolytic solution for driving an electrolytic capacitor of the present invention has an ultrafine particle inorganic compound dispersed in a solvent mainly composed of γ-butyrolactone, and one or both of hexites and boric acid. The ultrafine particle inorganic compound is charged in the electrolytic solution and becomes colloidal, so it can be uniformly dispersed in the electrolytic solution. In addition, when an oxide film is formed, the ultrafine inorganic compound adsorbs and aggregates to fill in the defective parts of the oxide film, making it possible to produce an oxide film with fewer defects.This makes it possible to increase the spark generation voltage, and In addition to this, by adding one or both of hexites and boric acid, the surface of the anodic oxide film is covered with the hexites, thereby making it possible to further increase the spark generation voltage.

Therefore, compared to conventional electrolytes, the spark generation voltage can be increased without reducing the specific conductivity, and the electrolyte with high conductivity can be used in a high voltage range, making it extremely Accordingly, it is possible to provide an electrolytic capacitor with low loss and less occurrence of short circuits.

Claims (9)

[Claims] Claim 1: A solvent mainly composed of γ-butyrolactone,
An electrolytic solution for driving an electrolytic capacitor in which an ultrafine inorganic compound is dispersed and one or both of hexites and boric acid is added and dissolved. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the ultrafine inorganic compound is a metal oxide. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the ultrafine inorganic compound is a metal nitride. 4. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the ultrafine inorganic compound is a metal carbide. 5. The electrolytic solution for driving an electrolytic capacitor according to claim 2, wherein the metal oxide is SiO2 and TiO2 alone or in a mixture. [Claim 6] The metal nitride is TiN, Si3N2, AlN.
, TaN, and Zr3N4, or a mixture of two or more thereof. 7. The electrolytic solution for driving an electrolytic capacitor according to claim 4, wherein the metal carbide is SiC and TiC alone or in a mixture. Claim 8: The size of the ultrafine inorganic compound is 100 nm.
The electrolytic solution for driving an electrolytic capacitor according to claim 1, which is as follows. [Claim 9] Hexites include mannitol, sorbitol,
The electrolytic solution for driving an electrolytic capacitor according to claim 1, which is one type or a mixture of two or more types selected from dulcit, xylitol, and pentaerythritol.