JPH03142815A - Electrolytic solution for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve withstand voltage characteristics while keeping high conductivity by adding specific polyglycerolalkyl (alkenyl) ether to electrolytic solution for an electrolytic capacitor whose main solvent is organic polar solvent and whose solute is organic acid, inorganic acid or salt thereof. CONSTITUTION:Polyglycerolalkyl (alkenyl) ether in an expression (I) is added to electrolytic solution for an electrolytic capacitor whose main solvent is organic polar solvent and whose solute is organic acid, inorganic acid or salt thereof. In the expression (I), (n) expresses an integer of 2 or more; and each of X1, X2, X3 expresses the same or different hydrogen atom, higher alcohol residue, higher acyl group and an expression (II); at the same time, at least one of them expresses higher alcohol residue. In the expression (II), (m) expresses an integer of 1 or more, R expresses ethyleneoxide and/or propyleneoxide; Y expresses hydrogen atom, higher acyl group and higher alcohol residue. It is desirable that (n) is between 2 and 20. Furthermore, (m) in the expression (II) is preferably between 1 and 100.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to improving an electrolyte for electrolytic capacitors,
In particular, it relates to an electrolytic solution for electrolytic capacitors with improved voltage resistance.

[Conventional technology]

A typical electrolytic capacitor consists of an anode electrode foil with an insulating oxide film layer formed on the surface of a roughened valve metal foil such as aluminum or tantalum, and a cathode electrode foil for current collection using electrolytic paper. The capacitor element is formed by winding the capacitor element through the capacitor, impregnated with an electrolytic solution, and housed in an exterior case.

The oxide film layer formed on the anode electrode foil of the capacitor element serves as a dielectric, and the electrolyte solution serves as an electrolyte layer. The electrolytic solution, which is this electrolyte layer, acts as a true cathode. That is, the electrolytic solution is interposed between the dielectric layer formed on the anode foil and the cathode foil for current collection, and its resistance is inserted in series with the electrolytic capacitor.

Therefore, if the conductivity of the electrolytic solution is low, the equivalent series resistance inside the electrolytic capacitor will increase, which will adversely affect the high frequency characteristics and loss characteristics. However, when the conductivity of the electrolyte is improved during boat fishing, the spark voltage tends to decrease, and the withstand voltage characteristics of the electrolytic capacitor may be impaired. Conversely, when various additives are added to improve the withstand voltage characteristics, the electrical conductivity decreases, resulting in increased loss.

Therefore, as a means to improve the withstand voltage characteristics of an electrolytic capacitor without reducing its conductivity, it has been proposed to add various additives to the electrolytic solution.

For example, sulfamic acid (JP-A-49-82963)
, superric acid (JP-A-49-133860), dodecyl phosphate (JP-A-49-73659), alkyl phosphoric acid (JP-A-52-153154), diphosphorous acid (JP-A-57-141913) ), boric acid-mannitol system (JP-A-57-60829), boric acid-mannitol-polyvinyl alcohol system (JP-A-59-177915), modified silicone oil (JP-A-1-175722), etc. be.

[Problem to be solved by the invention]

However, as the scope of use of electronic devices increases, there is a growing demand for improvements in the performance of electrolytic capacitors, and the conductivity of conventional electrolytes is no longer sufficient. Therefore, it is necessary to further improve the conductivity of the electrolytic solution, and as a result, it becomes difficult to maintain voltage resistance characteristics.

An object of the present invention is to provide an electrolytic solution that maintains high electrical conductivity and has improved withstand voltage characteristics.

[Means to solve the problem]

An electrolytic solution for electrolytic capacitors with an organic polar solvent as the main solvent and an organic acid, an inorganic acid, or a salt thereof as a solute has the general formula: (wherein, n is an integer of 2 or more, and Xl, Xl, and Xl are each the same or different hydrogen atoms, higher alcohol residues, higher acyl groups, −+R)=Y, and at least one represents a higher alcohol residue, and m in −+RhY
is an integer of 1 or more, R represents ethylene oxide and/or propylene oxide, and Y represents a hydrogen atom, higher acyl group, or higher alcohol residue).

In addition, n in the above general formula is not particularly limited as long as it is 2 or more, but if the degree of polymerization becomes extremely high, disadvantages such as difficulty in synthesis and decreased solubility will occur.
Preferably, about 2 or more and 20 or less is appropriate. Also, −
+ R)g m in Y is also desirably 1 or more and 100 or less.

Further, specific examples of higher alcohols corresponding to higher alcohol residues include hexyl alcohol, heptyl alcohol, octyl alcohol, caprylic alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, and electrolysyl alcohol. , pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol,
Examples include seryl alcohol, mericyl alcohol, oleyl alcohol, and phytol.

The fatty acid corresponding to a higher acyl group has the general formula: C
)Is(CHg), C00Il (n is an integer of 9 or more)
There are saturated fatty acids represented by, for example, undecylic acid (
n・9), lauric acid (n-10),) lysosylic acid (
n = 11), myristic acid (n - 12), pentadecylic acid (n 13), palmitic acid (n 14), heptadecylic acid (n = 15), stearic acid (n = 16), nonadecanoic acid (n = 17), arachic acid (n = 18), behenic acid (n = 20), lignoceric acid (n 22), cerotic acid (n = 24), heptacanoic acid (n 25), montanic acid (n 27) , melisic acid (n.28), lafcelic acid (n.30), and the like.

In addition, as unsaturated fatty acids, undecylic acid <10> (1
1), oleic acid (cis) <9> (18), elaidic acid (trans) <9> (18), cetoleic acid <1
1>(22), erucic acid (sis)<13>(22)
, brassic acid (trans) <13> (22), linoleic acid <9.12> (18), linuric acid <9+1115
>(18), arachidonic acid <5.8.11.14>(
20), stearol acid triple viscosity, 9> (18)
[The numbers in <> represent the positions of unsaturated bonds, and the numbers in parentheses represent the total number of carbon atoms].

The organic polar solvent that is the main solvent of the electrolyte according to the present invention includes monohydric alcohols such as ethanol, propatool, butanol, and pentanol, as well as polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, and methoxyethanol, as protic polar solvents. There are 6 alcohols and alcohol ethers,
Examples of aprotic polar solvents include amide polar solvents such as N-methylformamide, N,N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, T-butyrolactone, and N-methyl-2-pyrrolidone. , lactones such as ethylene carbonate, and cyclic amide-based solvents.Other examples include nitrile-based solvents such as acetonitrile, and oxide-based solvents such as dimethyl sulfoxide. They can be used in combination.

The electrolyte used in this invention is not particularly limited and may be any commonly used one. For example, as an anion source, organic acids such as aliphatic monocarboxylic acids such as formic acid and acetic acid, malonic acid, succinic acid, etc. These include aliphatic dicarboxylic acids and aromatic carboxylic acids such as benzoic acid and phthalic acid. Examples of inorganic acids include boric acid, phosphoric acid, and silicic acid. Examples of cation sources include monoalkylammonium cations such as ammonium and methylammonium, dialkylammonium cations such as dimethylammonium and diethylammonium, trialkylammonium cations such as trimethylammonium and triethylammonium, tetramethylammonium, and triethylmethylammonium. There are quaternary ammonium cations such as phosphonium and arsonium cations.

The electrolytic solution for an electrolytic capacitor according to the present invention is prepared by preparing 100 parts by weight of one or more of the above-mentioned organic polar solvents, and optionally containing 0 to 30 parts by weight of water and a solute consisting of an electrolyte substance in the supersolvent. It is sufficient to dissolve 1 to 50 parts by weight of the polyglycerol alkyl (alkenyl) ether alone or in combination, and preferably 0.1 to 20 parts by weight, more preferably Desired characteristics can be obtained by adding 0.5 to 6 parts by weight.

[For production]

The effect of improving the voltage resistance properties of the polyglycerin alkyl (alkenyl) ether used in this invention is as follows:
It is thought that the formation of a cell layer of polyglycerin alkyl (alkenyl) ether as a nonionic surfactant at the interface of the aluminum oxide film, which is the dielectric of the electrolytic capacitor, is involved.

〔Example〕

Examples of the electrolytic solution for electrolytic capacitors according to the present invention will be described below.

In each example, an electrolytic solution was prepared using the same solvent and solute as in the conventional example, and polyglycerol alkyl (alkenyl) ether was added thereto.

The following polyglycerin alkyl (alkenyl) ethers were used.

A) Polyoxyethylene distearate (POE=20
) polyglycerin oleyl ether (CI (zCH20%H [Lq, rlSl sum of t = 20] B) polyoxyethylene (2) and 10) polyoxypropylene (POP, 20) polyglycerin oleyl ether [p + (sum of br =10/sum of f, g, h=201
C) Polyglycerin tristearyl ether D) Polyoxypropylene (POP=30) Polyglycerin behenyl ether I3 [sum of p+q+r=301 E) Polyoxyethylene (POE=10) polyglycerin isostearyl ether [sum of p+Q+r+3=10] Polyglycerin oleyl ether 1st grade C) Polyglycerin tristearyl ether 1-4 days D> Polyoxypropylene (POP=30) Polyglycerin behenyl ether 10 days E ) Polyoxyethylene (POE, IO) Polyglycerin isostearyl ether (1 point, 1 size) and (D) In polyoxypropylene) P = 30) Polyglycerin behenyl ether As can be seen from the above results, the present invention Although the electrical conductivity of the electrolytic solution showed a tendency to be the same or slightly lower than that of the conventional example, the withstand voltage could be improved by about 10% to 50%.

[Effect of the invention] As described above, this invention uses an organic polar solvent as the main solvent,
General formula: % formula %) (In the formula, n is an integer of 2 or more, and X, , X, and X are each the same or different. A hydrogen atom, a higher alcohol residue, a higher acyl group, -fRhY, at least one of which represents a higher alcohol residue, in -fRhY, m is an integer of 1 or more, R represents ethylene oxide and/or propylene oxide, and Y is characterized by the addition of polyglycerin alkyl (alkenyl) ethers (representing hydrogen atoms, higher acyl groups, and higher alcohol residues), so by adding a small amount of these additives to a normal electrolytic solution, conductivity can be improved. It is possible to improve the withstand voltage characteristics while maintaining the temperature. Therefore, the electrical characteristics at high voltages are well stabilized, and the reliability of electrolytic capacitors using this electrolyte is improved.

Claims (1)

[Claims] (1) General formulas for electrolytic capacitor electrolytes with an organic polar solvent as the main solvent and an organic acid, an inorganic acid, or a salt thereof as a solute include: ▲Mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, n is 2 The above integers, X_1, X_3, and X_3 are the same or different hydrogen atoms, higher alcohol residues,
There are higher acyl groups, ▲mathematical formulas, chemical formulas, tables, etc.▼, and at least one shows a higher alcohol residue, ▲
There are mathematical formulas, chemical formulas, tables, etc. In ▼, m is an integer of 1 or more, R represents ethylene oxide and/or propylene oxide, and Y represents a hydrogen atom, a higher acyl group, or a higher alcohol residue. )
An electrolytic solution for electrolytic capacitors characterized by the addition of ether.