JPH03131012A - Electrolytic liquid for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve breakdown voltage characteristic and reliability of an electrolytic capacitor by making an organic polarity solvent as a main solvent and by adding a specific polyoxyethylene polyoxypropylene fatty ester to an electrolytic liquid for the electrolytic capacitor with an organic acid, an inorganic acid, or its salt as a dissolved substance. CONSTITUTION:In an electrolyte for an electrolytic capacitor, an individual or a plurality of organic polarity solvents are prepared by 100 weight pts.wt. and 1-50 pts.wt. may be dissolved by combining an individual or a plurality of dissolved substance consisting of an electrolytic substance into a solvent where water is mixed by 0-30 pts.wt. as needed. Then, by adding preferably 0.1-20 pts.wt. or further preferably 0.5-6 pts.wt. polyoxyethylene polyoxypropylene fatty ester which is shown by the expression I to this kind of electrolyte, a desired characteristic can be obtained.

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.

[Problems 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, with the general formula: % formula %) (where n is an integer of 1 or more, and R1 is a fatty acid residue) , R2 represents ethylene oxide and propylene oxide, and X represents a hydrogen atom, an acyl group, or a higher alcohol residue).

In addition, n in the above general formula is not particularly limited as long as it is 1 or more, but if the degree of polymerization becomes extremely high, disadvantages such as difficulty in synthesis and decreased solubility will occur.
Preferably, it is approximately 1 or more and 100 or less.

In addition, as fatty acids, there are saturated fatty acids represented by the general formula: CH3 (CHz) I, COOH (n is an integer of 9 or more), such as undecylic acid (n = 9), lauric acid (n = 10) ,
Tridecylic acid (n=11), myristic acid (n・12)
, pentadecylic acid (n 13), valmitic acid (n=1
4), heptadecylic acid (n・15), stearic acid (n
= 16), nonadecanoic acid (n = 17), arachidic 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), rough cellic acid (n・30), etc.

In addition, as unsaturated fatty acids, undecylic acid <10> (1
1), oleic acid (cis) <9> (18), elaidic acid (trans) <9> (1B), cetoleic acid <11> (22), erucic acid (sis) <13> (22)
), Brassidic acid (trans) <13> (22)
, linoleic acid <9.12> (18), linolenic acid <9.
12.15>(18), arachidonic acid<5.8.11
．． 14>(20), stearol acid triple bond, 9>
(18) [The numbers in <> represent the positions of unsaturated bonds, and the numbers in parentheses represent the total number of carbon atoms].

Specific examples of higher alcohols include hexyl alcohol, heptyl alcohol, octyl alcohol, caprylic alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, and heptadecyl alcohol. Decyl alcohol, stearyl alcohol, nonadecyl alcohol,
Examples include eicosyl alcohol, ceryl alcohol, mericyl alcohol, oleyl alcohol, and phytol.

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

Further, the electrolyte used in this invention is not particularly limited, and any commonly used electrolyte may be used. For example, anion sources include organic acids such as aliphatic monocarboxylic acids such as formic acid and acetic acid, aliphatic dicarboxylic acids such as malonic acid and succinic acid, and aromatic carboxylic acids such as benzoic acid and phthalic acid. , boric acid, phosphoric acid, silicic acid, etc. 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 adding a solute consisting of an electrolyte substance in a solvent mixed with 0 to 30 parts by weight of water as required. What is necessary is just to melt|dissolve 1-50 weight part individually or in combination of several. Desired characteristics can be obtained by adding preferably 0.1 to 20 parts by weight, more preferably 0.5 to 6 parts by weight of the polyoxyethylene polyoxypropylene fatty acid ester to such an electrolytic solution. be able to.

[Function] The effect of improving the withstand voltage characteristics of the polyoxyethylene polyoxypropylene fatty acid ester used in this invention is to add polyoxy as a nonionic surfactant to the interface of the aluminum oxide film, which is the dielectric of the electrolytic capacitor. It is thought that the formation of a micelle layer of ethylene polyoxypropylene fatty acid ester is involved.

[Examples] 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 polyoxyethylene polyoxypropylene fatty acid ester was added thereto. The following polyoxyethylene polyoxypropylene fatty acid esters were used.

Propylene (POP・40) stearate B)
Polyoxyethylene oleate (POE=40) Polyoxypropylene (POP=20) Cetyl ether OC1
+.

C1zll+ :l-C-0+ CH2CIIZOhv
+ CI (-CH2OhrCI 6113 :1C) polyoxyethylene (POE=20) polyoxypropylene (POP=5) diundecylenic acid ester D) polyoxyethylene palmitate (POE=50) polyoxypropylene (POP=3) oleyl Ether E) Polyoxyethylene (POE=20) Polyoxypropylene (
POP・50) Behenic acid ester o C113 CIl* + C1h +rrC-0+C82C112
0-hT+Ctl -CHzObTH Thick] 1 jar 1 Cold] 11 Stearic acid ester fruit 1st "Ura 11" - Dai 11" UP=JJf Rail Ether Large 1st I Yudai 1st 11 From the above results As can be seen, although the electrical conductivity of the electrolytic solution of the present invention tends to be the same or slightly lower than that of the conventional example, the withstand voltage was able to 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,
An electrolytic solution for electrolytic capacitors containing an organic acid, an inorganic acid, or a salt thereof as a solute has a general formula: % formula %) (where n is an integer of 1 or more, RI is a fatty acid residue, R2 is ethylene oxide and propylene oxide, It is characterized by the addition of polyoxyethylene polyoxypropylene fatty acid ester (X represents a hydrogen atom, acyl group, or higher alcohol residue), so by adding a small amount of these additives to a normal electrolyte Withstand voltage characteristics can be improved while maintaining electrical conductivity. Therefore, the electrical characteristics at high voltages are well stabilized, and the reliability of the electrolytic capacitor using the second electrolyte is improved.

Special permission Out wish Man Nippon Chemi-Con Co., Ltd.

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 1 an integer greater than or equal to R_1 is a fatty acid residue, R_
2 is an electrolytic solution for an electrolytic capacitor, characterized in that a polyoxyethylene polyoxypropylene fatty acid ester of ethylene oxide and propylene oxide (X represents a hydrogen atom, an acyl group, or a higher alcohol residue) is added.