JPH04145616A - Electrolytic solution for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve a withstanding voltage without affecting other characteristics adversely by adding titanium dioxide in electrolytic solution using ethylene glycol as dispersion solvent. CONSTITUTION:Titanium dioxide is added to electrolytic solution using ethylene glycol as dispersion solvent. This colloid is TiO2 hydrate TiO2.xH2O (x=1 to 10) having a size of 5 to 50mum and polymer particles thereof exist with cations as stabilizer in electrolytic solution. If such electrolytic solution is introduced into an element, an insulating layer of TiO2 is readily formed on an aluminum oxide surface since TiO2 itself is negatively charged. The insulating layer effectively functions to improve a withstanding voltage of a capacitor; however, it does not affect adversely other characteristics such as capacity and tan delta.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to improvement of an electrolytic solution for electrolytic capacitors, and more specifically, by dispersing an inorganic oxide colloid in the electrolytic solution, it is possible to improve an electrolytic solution for other electrolytic capacitors. The present invention relates to an electrolytic solution for electrolytic capacitors that significantly improves withstand voltage without adversely affecting electrical characteristics.

[Prior art] Electrolytic capacitors are small, large capacity, inexpensive, and exhibit excellent characteristics such as smoothing rectified output, and are one of the important components of various electrical and electronic devices. It is produced by using an aluminum film that has been oxidized to an oxide film as an anode, and using this oxide film as a dielectric with an electrolyte interposed between it and a current collecting cathode. During use, it is stable because the oxide film is constantly regenerated, but if it is not used for a long time, for example, regeneration becomes insufficient and it deteriorates.

Since electrolytic capacitors are used while undergoing chemical reactions, their characteristics largely depend on the properties of the electrolyte. Maintaining a steady state of the chemical reaction that occurs between the aluminum electrode, which has an oxide film on its surface, and the electrolyte, and maintaining the aluminum oxide film, which serves as a dielectric, in good condition is important for stabilizing performance. If the chemical steady state is disturbed due to an incorrect method, for example, due to an excessively high voltage load, the aluminum oxide film will be destroyed and eventually the insulation will be broken.

Scintillation is a phenomenon in which the electrochemical state fluctuates as a result of a change in the physical properties of the dielectric due to the high voltage load that occurs when the load voltage of the capacitor increases, resulting in a temporal change in dielectric constant.The voltage at which this phenomenon is observed is The scintillation voltage (spark voltage) can be used as a measure of the voltage resistance of the capacitor, and the higher the scintillation voltage (spark voltage), the greater the voltage resistance of the capacitor.
This can be easily done by immersing an unformed aluminum foil of an appropriate size in the electrolyte to be measured, without assembling the final capacitor product.

Conventionally, boric acid, mannitol, silicone oil, polyvinyl alcohol, or a mixture thereof has been used to improve the withstand voltage. In addition to these, attempts have been made to improve the electrolytic solution for electrolytic capacitors and obtain high voltage resistance by adding various additives.

Examples of additives for obtaining high voltage resistance include the addition of sulfamic acid (Japanese Patent Application Laid-open No. 4982963), the addition of superic acid (Japanese Patent Application Laid-open No. 133860-1982), and the addition of dodecyl phosphate (Japanese Patent Application Laid-open No. 1982-133860). 49-73659), addition of alkyl phosphoric acid (JP-A-52-153154), addition of diphosphorous acid (JP-A-57-141913), boric acid -
The use of mannitol (Japanese Unexamined Patent Publication No. 57-60829) and the use of boric acid-mannitol-polyvinyl alcohol (Japanese Unexamined Patent Publication No. 59-177915) have been proposed; It has not always been possible to sufficiently improve the withstand voltage without causing any adverse effects.

[Problem to be solved by the invention] The present invention provides an electrolytic capacitor that significantly improves withstand voltage without adversely affecting other properties of the electrolytic capacitor by dispersing an inorganic oxide colloid in an electrolytic solution. The purpose is to provide an electrolyte.

[Means for Solving the Problems] According to the present invention, there is provided an electrolytic solution for driving an electrolytic capacitor, which is used in an electrolytic capacitor in which an anodized film of a valve metal is used as a dielectric and a cathode is taken out through the electrolytic solution. An electrolytic solution for an electrolytic capacitor is provided, which is characterized in that titanium dioxide using ethylene glycol as a dispersion solvent is added to the electrolytic solution.

The electrolytic solution for an electrolytic capacitor according to the present invention is suitable as an electrolytic solution for driving an aluminum electrolytic capacitor, if the main solvent is an organic polar solvent and the solute is an organic acid, an inorganic acid, or a salt thereof.

Specific examples of solvents that can be used alone or in combination as the organic polar solvent of the electrolyte include the following: Proton ethanol, propatool, butanol, pentanol, hexanol, cyclobutanol, cyclopene Monohydric alcohols such as tanol, cyclohexanol, and benzyl alcohol, polyhydric alcohols and alcohol ethers such as ethylene glycol, propylene glycol, glycerin, methoxyethanol, ethoxyethanol, methoxypropylene glycol, and dimethoxypropanol, aprotic polar dimethylformamide, N,N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide, and hexa Amide solvents such as methylphosphoric amide, lactones such as γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, and isobutylene carbonate, cyclic amide solvents, aliphatic amine solvents such as triethylamine, acetonitrile, etc. Nitrile solvents, oxide solvents such as dimethyl sulfoxide.

Specific examples of electrolytes that can be used alone or in combination in the electrolyte of an organic acid, an inactive acid, or a salt thereof include the following electrolytes: 1. Formic acid, acetic acid, propionic acid, enanthate. Aliphatic monocarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, methylmalonic acid, pimelic acid, superric acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, citraconic acid, and itaconic acid Aliphatic dicarboxylic acids such as benzoic acid, phthalic acid, salicylic acid, toluic acid, and aromatic carboxylic acids such as pyromellitic acid, inorganic acids such as boric acid, phosphoric acid, silicic acid, HBF, HP Fa, etc. , ammonium ammonium (NH,), monoalkylammoniums such as methylammonium, ethylammonium, and propylammonium; dialkylammoniums such as dimethylammonium, diethylammonium, ethylmethylammonium, and dibutylammonium; trimethylammonium, triethylammonium, and tributylammonium. trialkylammoniums such as tetramethylammonium, triethylmethylammonium, tributylammonium, tetraethylammonium, and quaternary ammoniums such as N,N-dimethylpyrrolidinium.
Grade ammonium, i-type phosphonium and arsonium, and other mannitols can also be used.

In the electrolytic solution for electrolytic capacitors of the present invention, preferably 1 to 20 parts by weight of ethylene glycol is used as a dispersion solvent.

By adding preferably 0.1 to 5 parts by weight, more preferably 1 to 3 parts by weight of titanium dioxide using the above-mentioned ethylene glycol as a dispersion solvent, to an electrolytic solution consisting of such a solute-solvent system, A significant improvement in voltage resistance can be achieved.

[Function] As mentioned above, since electrolytic capacitors are used while carrying out a chemical reaction, their characteristics depend largely on the properties of the electrolyte. It is important to maintain the steady state of the chemical reactions involved and to maintain the aluminum oxide film that serves as the dielectric in good condition for stabilizing performance.

The present invention is characterized in that titanium dioxide using ethylene glycol as a dispersion solvent is added to the electrolytic solution. This colloid is composed of hydrated TiO□ having a size of 10 to 50 mμ (Tilt x H2O, x = 1 to 10),
The polymer particles exist using cations in the electrolyte as stabilizers.

When such an electrolyte is impregnated into a device, TiO2 itself is negatively charged, so TiO2 is deposited on the aluminum oxide surface.
z insulating layer is easily formed. This insulating layer effectively acts to improve the withstand voltage of the capacitor, but does not adversely affect other characteristics.

Due to these effects, the electrolytic solution for electrolytic capacitors according to the present invention has a remarkable effect on stabilizing the chemical steady state of the electrochemical reaction system consisting of the anode, cathode, aluminum oxide film dielectric, and electrolyte of the electrolytic capacitor. It is presumed that they are staying together.

[Effects of the Invention] According to the present invention, an electrolytic solution for an electrolytic capacitor is provided that significantly improves the withstand voltage without adversely affecting other characteristics of the electrolytic capacitor by dispersing an inorganic oxide colloid in the electrolytic solution. is provided.

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples.

1 and above Jl Titanium dioxide was dispersed at a predetermined concentration using ethylene glycol as a dispersion solvent using an electrolytic shell for an electrolytic capacitor consisting of the following components. ! Addition amounts of components are shown in weight percent.

X1 Eyu L Yu ■Yu γ-Butyrolactone 69 69.5 Maleic acid 10 10.5 Triethylamine 77.5 Ethylene glycol 12 12.5 Titanium dioxide 2 Using these electrolytes, an electric ax capacitor was produced by a conventional method. . The pH5 specific resistance and spark voltage of the electrolyte are shown below.

pH-4, 14, 1 of cold 1ueyu L-bed 5yu electrolyte Specific resistance (Ω・cm) 155 150 Spark voltage (V) 110 90 Example 2 and
I2 Using an electrolytic solution for an electrolytic capacitor consisting of the following components, titanium dioxide was dispersed at a predetermined concentration using ethylene glycol as a dispersion solvent. The amount of each component added is shown in % by weight.

Summer 1 Eyu Tane! Dish l γ-Butyrolactone 62 62.3 Maleic acid 99.3 Boric acid 22.3 Mannitrate 22.3 Triethylamine 66.3 Ethylene glycol 17 17.5 Titanium dioxide 2 Using these electrolytes, create an electrolytic capacitor by the usual method. Created. The pH1 specific resistance and spark voltage of the electrolyte are shown below.

K group 5 Yu skin control Electrolyte pH'3.5 3.5 Specific resistance (Ω・cn) 210 205 Spark voltage (V) 165 145 Example 3 and
J3 Using an electrolytic solution for an electrolytic capacitor consisting of the following components, titanium dioxide was dispersed at a predetermined concentration using ethylene glycol as a dispersion solvent. The amount of each component added is shown in % by weight.

X Toyotanyu 凰爙■Yuethylene glycol 85 85.8 Ammonium benzoate 88.6 Water 5 5.6
Titanium Dioxide 2 Using these electrolytes, electrolytic capacitors were produced by a conventional method. The pH1 specific resistance and spark voltage of the electrolyte are shown below.

X1 Eyu Arashito Sarayu electrolyte pH 6,46,6 Specific resistance (Ω・ci) ・340 338 Spark voltage (V) 325 295j4 and
4 Using an electrolytic solution for an electrolytic capacitor consisting of the following components, titanium dioxide was dispersed at a predetermined concentration using ethylene glycol as a dispersion solvent. The amount of each component added is shown in % by weight.

X1 Ethylene glycol 87 Ammonium benzoate 5 Boric acid 4 Mannitol 2 Titanium dioxide 2 An electrolytic capacitor was prepared by a conventional method using these electrolytes, and the DH1 specific resistance and spark voltage of the electrolyte were shown below. .

Eblin ■I L Autumn■1 Electrolyte pH5,75,7 Specific resistance (Ω・am) 620 615 Spark voltage (V) 460 420''5 and
j5 Using an electrolytic solution for an electrolytic capacitor consisting of the following components, titanium dioxide was dispersed at a predetermined concentration using ethylene glycol as a dispersion solvent. The amount of each component added is shown in weight%.

K152 Lestan diethylene glycol 6970 Boric acid 12 12.5 Ammonium borate 17 17.5 Titanium dioxide
2 Using these electrolytes, electrolytic capacitors were produced by a conventional method. The pH 3 specific resistance and spark voltage of the electrolyte are shown below.

Ura Zokumai J Cheifu Ju Electrolyte pH 4゜14.1 Specific resistance (Ω・cr'I) 840 g30
Spark voltage (V) 580 540 I6 and Example 6 Using an electrolytic solution for an electrolytic capacitor consisting of the following components, titanium dioxide was dispersed at a predetermined concentration using ethylene glycol as a dispersion solvent. The amount of each component added is shown in % by weight.

Ill Glossy Ethylene Glycol 8282.5 1.6-Decanedicarbone 1
1 11.5 boric acid
33.5 Mannite 22.5 Titanium Dioxide 2 Using these electrolytes, electrolytic capacitors were fabricated by a conventional method.The pH5 specific resistance and spark voltage of the solution are shown below.

From the above results, the electrolytic solution for electrolytic capacitors according to the present invention can be used in addition to electrolytic capacitors. It can be seen that this material significantly improves the withstand voltage without having any adverse effect on the mechanical properties.

Claims (1)

[Claims] (1) An electrolytic solution for driving an electrolytic capacitor used in an electrolytic capacitor in which an anodized film of a valve metal is used as a dielectric and a cathode is taken out through the electrolytic solution, and the electrolytic solution uses ethylene glycol as a dispersion solvent in the electrolytic solution. An electrolytic solution for electrolytic capacitors characterized by the addition of titanium.