JPH03151618A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve breakdown strength characteristics while keeping high electric conductivity, by adding specified 3-methyl pentane-1,3,5-triol-fatty ester to the electrolyte for an electrolytic capacitor wherein organic polar solvent is used as main solvent, and organic acid or inorganic acid or its salt is used as solute. CONSTITUTION:3-methylpentane-1,3,5-triol fatty ester expressed by a formula I is added to electrolyte for an electronic capacitor wherein organic polar solvent is used as main solvent, and organic acid or inorganic acid or its salt is used as solute. (in the above formula I, X1, X2 and X3 are identical or different hydrogen atom, higher acyl group, and -(R)n-Y, at least one is higher acyl group, (n) in -(R)n-Y is an integer larger than or equal to 1, R indicates ethylene oxide and/or propylene oxide, and Y shows hydrogen atom, and higher acyl group). By adding a small amount of the above additive to the ordinary electrolyte, the breakdown strength characteristics can be improved while electric conductivity is maintained.

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), hypophosphorous 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 (Japanese Unexamined Patent Publication No. 1-175722) and the like.

[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]

The general formula: , →R)T Y, and at least one is a higher acyl group, -(-Rh Y
3-methylpentane-1,3,5-1, where n is an integer of 1 or more, R is ethylene oxide and/or propylene oxide, and Y is a hydrogen atom or a higher acyl group)
-It is characterized by the addition of lyol fatty acid ester.

In addition, n in the above general formula is not particularly limited as long as it is 1 or more;
Preferably, it is approximately 1 or more and 100 or less.

As fatty acids corresponding to higher acyl groups, general 2: C1
13 (CHz), IC0OII (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), tridecylic 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), arachidic acid (n = 18), behenic acid (n = 20), lignoceric acid (n 22), heptalotine fi (n = 24), heptacanoic acid (n = 25)
, montanic acid (n・27), lauric acid (n=28)
, rough cellic acid (n=30), and the like.

In addition, as unsaturated fatty acids, undecylic acid <10> (1
1), oleic acid (cis) <9> (1B), elaidic acid (trans) <9> (1B), cetoleic acid <
11>(22), erucic acid (sis)<13>(22)
, Brassidic acid (trans) <13> (22), Linoleic acid <9.12> (1B), Rilunic acid <9.12+
15>(1B), arachidonic acid<5.8, 11.14
> (20), stearol acid triple bond, 9 > (1
8) [<> indicates the position of an unsaturated bond, and () indicates 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 alcohols and alcohol ethers, and aprotic polar solvents include amide polar solvents such as N-methylformamide, N,N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, etc. -Lactones such as butyrolactone, N-methyl-2-pyrrolidone, and ethylcarbonate, and cyclic amide-based solvents are mentioned, as well as nitrile-based solvents such as acetonitrile, and oxide-based solvents such as dimethyl sulfoxide as aprotic polar solvents. For example, 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. Then, the above-mentioned 3-methylpentane-C3,5-
) Liol fatty acid ester, preferably 0.1 to 20
Desired characteristics can be obtained by adding 0.5 to 6 parts by weight, more preferably 0.5 to 6 parts by weight.

[For production]

The effect of improving the withstand voltage characteristics of the 3-methylpentane-C3,5-triol fatty acid ester used in this invention is to add 3-methyl 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 pentane-C3,5-1-liol 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 3-methylpentane-1,3,5-)liol fatty acid ester was added thereto. Then add 3 methyl pencun-1,3
, 5-triol fatty acid esters used were as follows.

B) Polyoxyethylene (POE=IO) Polyoxypropylene (POP=30) 3-methylpentane-1,3
,5-) Liol dioleic acid ester II C1l□OCC+&3 CH2C1+3 CH3CO+CHzCI (zo return Ctl-CHzOhr
llC11□ 0 1 C1l□OCCt&i A) Polyoxyethylene (POE=40)-3-methylpentane-C3,5-triol monostearate 1h CI (zo CCl,, 1lis CH.

C-0+CII□CII□O-+1-11CI+.

CH20-(-CHzCHzO-)-II [sum of p, q-40] C) Polyoxypropylene behenate (POP=20)-
3-methylpentane 1.3.5-) liol monolaurate 1 (carp to CGIIlt□.

Cl-12co.

1 CH3-c-o+co-cuzo rotation C-C,,11□3
C11, C1l.

CII□O+ CH-C1lzO Homare 11 [sum of p, q -20ko0 D) Polyoxyethylene civalmitate (POE=30
) -3-0 1 CHzO-CC+&5 C) I3 C■, O I C-0+Cl-12CI+20uyCCl51131C
H,,0 1 CH20+ CHzCHzO square CCl5H31[p,Q
Sum of -301 E) 3-Methylpentane-1,3,5-triol monooleate ester 1 1□OC-Cl5H3 1Hz Ctli C-side al.

1□0-11 Large" 1E) Firefly (P114 3 Large 1 Note 5 major grooves d1 Dan 4 Island-1- Large 41 Special 1 The electrical conductivity of the liquid tends to be the same or slightly lower than the conventional example. However, 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, X, X2, X3 are each the same or different hydrogen atom, higher acyl group, →R) i Y, and at least one is a higher acyl group, →R-)= n in Y is an integer of 1 or more, R is ethylene oxide and/or propylene oxide, Y is a hydrogen atom, and represents a higher acyl group) It is characterized by the addition of 3-methylbencune-L3,5-) lyol fatty acid ester, so by adding a small amount of these additives to a normal electrolyte, it is possible to improve withstand voltage characteristics while maintaining conductivity. can be done. 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, X_1, X_2 , X_3 are each the same or different hydrogen atom, higher acyl group, ▲ has a mathematical formula, chemical formula, table, etc. ▼ Y, and at least one is a higher acyl group, ▲ has a mathematical formula, chemical formula, table, etc. ▼ Y n is an integer of 1 or more, R is ethylene oxide and/
An electrolytic solution for an electrolytic capacitor, characterized in that a 3-methylpentane-1,3,5-triol fatty acid ester of propylene oxide (Y represents a hydrogen atom or a higher acyl group) is added.