JP2012151376A - Electrolytic solution for aluminum electrolytic capacitor, and aluminum electrolytic capacitor using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic solution for an aluminum electrolytic capacitor which limits swelling of a capacitor due to heat (260°C) of a solder reflow furnace while having a sufficient electric conductivity.SOLUTION: The electrolytic solution for an aluminum electrolytic capacitor contains at least one kind selected from tertiary amine salts represented by a specific chemical formula. Preferably, Xis carboxylate anion of 1-20C, preferably an organic solvent is contained, and the organic solvent is γ-butyrolactone or a mixed solvent containing γ-butyrolactone.

Description

  The present invention relates to an electrolytic solution for an aluminum electrolytic capacitor and an aluminum electrolytic capacitor using the same.

  In recent years, lead-free solder used in electronic components has been promoted in order to reduce the use of environmentally hazardous substances. In order to cope with this lead-free solder, it is necessary to increase the temperature during the reflow process to 260 ° C. However, the conventional aluminum electrolytic capacitor using the driving electrolytic solution has a problem that gas is generated from the electrolytic solution due to the heat of the solder reflow furnace, and the capacitor opens and swells.

  In response to this problem, a method is disclosed in which the vapor pressure of the electrolyte is reduced to suppress swelling, the evaporation of the solvent is suppressed, the increase in internal pressure in the capacitor during reflow under high temperature, and the blistering is suppressed. Has been. (For example, Patent Documents 1 and 2)

JP 2006-186214 A JP2007-59611A

However, in the case of using the electrolyte solution as in Patent Documents 1 and 2, the swelling due to the reflow temperature can be suppressed by using the additive, but the conductivity of the electrolyte solution is lowered by increasing the viscosity of the electrolyte solution. There was a problem that.

That is, an object of the present invention is to solve the problems associated with the prior art as described above, wherein the swelling of the capacitor due to the heat (260 ° C.) of the solder reflow furnace is small, and sufficient electric conductivity is obtained. It is an object to provide an electrolytic solution for an aluminum electrolytic capacitor and an aluminum electrolytic capacitor using the electrolytic solution.

［一般式（１）、（２）において、ｎ、ｍ、ｌは２または３の整数、Ｘ₁ ⁻、Ｘ_２ ⁻は対アニオン（ｂ）である。］ As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention. That is, the present invention comprises at least one selected from the group consisting of a tertiary amine salt (A) represented by general formula (1) and a tertiary amine salt (B) represented by general formula (2). An electrolytic solution for an aluminum electrolytic capacitor, and an aluminum electrolytic capacitor using the electrolytic solution.

[In General Formulas (1) and (2), n, m, and l are integers of 2 or 3, and X ₁ ⁻ and X ₂ ⁻ are a counter anion (b). ]

  The electrolytic solution for an aluminum electrolytic capacitor of the present invention has a sufficient electrical conductivity with small expansion of the capacitor due to heat (260 ° C.) of a solder reflow furnace.

The electrolyte (C) of the electrolytic solution (G) for an aluminum electrolytic capacitor of the present invention includes a tertiary amine salt (A) represented by the general formula (1) and a tertiary amine salt represented by the general formula (2). It contains at least one selected from the group consisting of (B).

Examples of amines which are cation components (A) and (B) and are conjugate bases thereof include the following.
A cationic component of (A), the conjugate base N, N-dimethylaminoethanol (n = 2),
N, N-dimethylaminopropanol (n = 3)
A cationic component of (B), the conjugate base N-methyl-iminodiethanol (m = 2, l = 2),
N-methyl-iminodipropanol (m = 3, l = 3),
N-hydroxyethyl-N-methylaminopropanol (m = 2, l = 3),
Of these, N, N-dimethylaminoethanol (n = 2) and N-methyl-iminodiethanol (m = 2, l = 2) are preferable.

  Examples of the counter anion (b) include a carboxylate anion (b1) and a phosphate ester anion (b2), and (b1) is preferred.

The carboxylate anion (b1) is preferably a C1-C20 carboxylate anion, and specific examples thereof include the polycarboxylic acid and monocarboxylic acid monoanions listed below. In polycarboxylic acid, by making equimolar reaction between polycarboxylic acid and amine, it becomes a monovalent anion in which one of a plurality of carboxyl groups present in one molecule is ionically bonded with ammonium cation (a). Is preferred.

Polycarboxylic acid 2- to 4-valent polycarboxylic acid having 2 to 15 carbon atoms: aliphatic polycarboxylic acid [saturated polycarboxylic acid (oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, Azelaic acid, sebacic acid, 2-butyloctanedioic acid, etc.), unsaturated polycarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.)], aromatic polycarboxylic acids [phthalic acid, isophthalic acid, terephthalic acid, trimellit Acid, pyromellitic acid, etc.], S-containing polycarboxylic acid [thiodibropionic acid, etc.].

Monocarboxylic acid C2-C20 oxycarboxylic acid: aliphatic oxycarboxylic acid [glycolic acid, lactic acid, tartaric acid, castor oil fatty acid, etc.]; aromatic oxycarboxylic acid [salicylic acid, mandelic acid, etc.];
Monocarboxylic acid having 1 to 20 carbon atoms: aliphatic monocarboxylic acid [saturated monocarboxylic acid (formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, uraric acid , Myristic acid, stearic acid, etc.), unsaturated monocarboxylic acids (acrylic acid, methacrylic acid, crotonic acid, oleic acid, etc.)]; aromatic monocarboxylic acids [benzoic acid, cinnamic acid, naphthoic acid, etc.]
Of the polycarboxylic acids and monocarboxylic acids, phthalic acid, maleic acid, and benzoic acid are preferred.

The alkyl phosphate anion (b2) includes a monoanion of a monoalkyl phosphate and a monoanion of a dialkyl phosphate. Specific examples are shown below.
Monoalkyl phosphate ester: monomethyl phosphate ester, monoethyl phosphate ester, monopropyl phosphate ester [mono (n-propyl) phosphate ester, mono (iso-propyl) phosphate ester], monobutyl phosphate ester [mono (n- Butyl) phosphate, mono (iso-butyl) phosphate, and mono (tert-butyl) phosphate], monopentylphosphate, monohexylphosphate, monoheptylphosphate, monooctylphosphate Esters [mono (2-ethylhexyl) phosphate ester and the like] and the like.

Dialkyl phosphate: dimethyl phosphate, diethyl phosphate, dipropyl phosphate [di (n-propyl) phosphate, di (iso-propyl) phosphate], dibutyl phosphate [di (n-butyl) Phosphate ester, di (iso-butyl) phosphate ester, and di (tert-butyl) phosphate ester], dipentyl phosphate ester, dihexyl phosphate ester, diheptyl phosphate ester, dioctyl phosphate ester [bis (2-ethylhexyl) ) Phosphate ester etc.] etc.

Preferred examples of the tertiary amine salt (A) include N, N-dimethylaminoalcohol / carboxylate and N, N-dimethylaminoalcohol / alkyl phosphate ester salt, and more preferred is N, N-dimethylamino. Alcohol carboxylate. Specific examples include N, N-dimethylaminoethanol phthalate, N, N-dimethylaminopropanol phthalate, N, N-dimethylaminoethanol diethyl diethyl ester, N, N-dimethylaminopropanol. Examples thereof include diethyl phosphate.

Preferred examples of the tertiary amine salt (B) include N-methyl-iminodialcohol / carboxylate and N-methyl-iminodialcohol / alkyl phosphate ester salt, and more preferred is N-methyl-iminodiamine. Alcohol carboxylate. Specific examples include N-methyl-iminodiethanol phthalate, N-methyl-iminodipropanol phthalate, N-methyl-iminodiethanol diethyl diethyl ester, N-methyl-iminodipropanol dimethyl Examples thereof include phosphate ester salts. Among these, those which are liquid at room temperature are N, N-dimethylaminoethanol / diethyl phosphate ester salt, N-methyl-iminodiethanol / diethyl phosphate ester salt, N-methyl-iminodiethanol / phthalic acid salt. Examples include salt. These do not contain an organic solvent (D) and can constitute the electrolytic solution of the present invention only with a tertiary amine salt.

<Organic solvent (D)>
Examples of the organic solvent (D) include (1) alcohol, (2) ether, (3) amide, (4) oxazolidinone, (5) lactone, (6) nitrile, (7) carbonate, (8) sulfone, and (9 ) Other organic solvents are included.

(1) Alcohol Monohydric alcohol (methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, benzyl alcohol, amino alcohol, furfuryl alcohol, etc.) Dihydric alcohol (ethylene glycol, propylene glycol, diethylene glycol, hexylene) Glycol, etc.), trihydric alcohol (glycerin, etc.), tetravalent or higher alcohol (hexitol, etc.), etc.

(2) Ether monoether (ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, etc.), diether (ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol mono Ethyl ether), triether (diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.), etc.

(3) Amide formamide (N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, etc.), acetamide (N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide) N, N-diethylacetamide, etc.), propionamide (N, N-dimethylpropionamide, etc.), pyrrolidone (N-methylpyrrolidone, N-ethylpyrrolidone, etc.), hexamethylphosphorylamide, etc.

(4) Oxazolidinone N-methyl-2-oxazolidinone, 3,5-dimethyl-2-oxazolidinone, and the like.

(5) Lactone γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, δ-valerolactone, and the like.

(6) Nitrile Acetonitrile, propionitrile, butyronitrile, acrylonitrile, methacrylonitrile, benzonitrile and the like.

(7) Carbonate Ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and the like.

(8) Sulfone sulfolane, dimethyl sulfone, ethyl methyl sulfone, ethyl isopropyl sulfone, ethyl isobutyl sulfone and the like.

(9) Other organic solvents 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, aromatic solvents (toluene, xylene, etc.) paraffin solvents (normal paraffin, isoparaffin, etc.) and the like.

  The organic solvent (D) may be used alone or in combination of two or more. Of these, lactones and sulfones are preferable, and γ-butyrolactone and sulfolane are more preferable. Most preferred is a mixed solvent containing γ-butyrolactone and γ-butyrolactone. Examples of the solvent other than γ-butyrolactone in the mixed solvent include ethylene glycol, sulfolane, 1,3-dimethyl-2-imidazolidinone, and the weight ratio thereof is γ-butyrolactone: solvent other than γ-butyrolactone = 50. : 50 to 95: 5 is preferable.

The electrolytic solution (G) for an aluminum electrolytic capacitor of the present invention preferably comprises an electrolyte (C) and an organic solvent (D). In that case, the weight ratio of (C) :( D) is 10:90 to 40: 60 is preferable, and 15:85 to 25:75 is more preferable.

The electrolyte (C) is at least one selected from the group consisting of a tertiary amine salt (A) and a tertiary amine salt (B), but if necessary, other electrolytes conventionally used for electrolytic solutions for aluminum electrolytic capacitors (E) may be contained. Other electrolytes (E) include primary amines such as ammonia, methylamine and ethylamine, secondary amines such as dimethylamine, ethylmethylamine and diethylamine, tertiary amines such as trimethylamine, dimethylethylamine and triethylamine, 1,5- Carboxylate or alkyl phosphate ester salt such as amidine such as diazabicyclo [4,3,0] -5-nonene, 1-methyl-1,4,5,6-tetrahydropyrimidine, 1,2,4-trimethylimidazoline Etc.

The weight ratio of the total weight of the tertiary amine salt (A) and tertiary amine salt (B) to the other electrolyte (E) is preferably 50:50 to 100: 0, more preferably 80:20 to 100. : 0.

Moreover, the various additives normally used for electrolyte solution can be added to the electrolyte solution (G) for aluminum electrolytic capacitors of this invention. Examples of the additive include boric acid derivatives (for example, boric acid, complex compounds of boric acid and polysaccharides (mannitol, sorbit, etc.), complex compounds of boric acid and polyhydric alcohols (ethylene glycol, glycerin, etc.), etc. ), Nitro compounds (for example, o-nitrobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, o-nitrophenol, p-nitrophenol, etc.). The addition amount is preferably 5 wt% (hereinafter referred to as wt%) based on the weight of the electrolytes (A), (B) and the organic solvent (D) from the viewpoint of specific conductivity and solubility in the electrolytic solution. Sometimes). Hereinafter, 2 wt% or less is particularly preferable.

The electrolytic solution of the present invention is suitable for an aluminum electrolytic capacitor. The aluminum electrolytic capacitor is not particularly limited. For example, it is a scraped aluminum electrolytic capacitor, and a separator is provided between an anode (aluminum oxide foil) in which aluminum oxide is formed on the anode surface and a cathode aluminum foil. A capacitor formed by winding with an interposition is exemplified. The separator is impregnated with the electrolytic solution of the present invention as a driving electrolytic solution, and is housed in a bottomed cylindrical aluminum case together with a positive electrode, and then the aluminum case opening is sealed with a sealing rubber to form an aluminum electrolytic capacitor. be able to.

Next, specific examples of the present invention will be described, but the present invention is not limited thereto.

Example 1
[Production of N, N-dimethylaminoethanol phthalate / γ-butyrolactone electrolyte]
In 500 mL four-necked colben, 24 parts of phthalic acid was charged, and 113 parts of γ-butyrolactone was added and suspended. Thereto, 13 parts of N, N-dimethylaminoethanol was added and stirred until the solution became homogeneous to obtain 150 parts of an N, N-dimethylaminoethanol / phthalate electrolyte solution (25% by weight).

Example 2
[Production of N, N-dimethylaminopropanol / phthalate electrolyte]
The same as Example 1 except that 23 parts of phthalic acid was used instead of 24 parts of phthalic acid and 14 parts of N, N-dimethylaminopropanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 13 parts of N, N-dimethylaminoethanol. As a result, 150 parts of an N, N-dimethylaminopropanol / phthalate electrolyte solution (25% by weight) was obtained.

Example 3
[Production of N-hydroxyethyl-N-methylaminoethanol / phthalate electrolyte]
Example except that instead of 24 parts of phthalic acid, 22 parts of phthalic acid and 16 parts of N-hydroxyethyl-N-methylaminoethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 13 parts of N, N-dimethylaminoethanol were used. In the same manner as in Example 1, 150 parts of an N-hydroxyethyl-N-methylaminoethanol / phthalate electrolyte solution (25 wt%) was obtained.

Example 4
[Production of N-hydroxyethyl-N-methylaminoethanol / phthalate electrolyte solution (15 wt%)]
Example 3 was used except that 13 parts of phthalic acid instead of 22 parts of phthalic acid and 9 parts of N-hydroxyethyl-N-methylaminoethanol were used instead of 16 parts of N-hydroxyethyl-N-methylaminoethanol. 150 parts of N-hydroxyethyl-N-methylaminoethanol / phthalate electrolyte solution (15% by weight) were obtained.

Example 5
[Production of N, N-dimethylaminoethanol phthalate / triethylamine phthalate electrolyte]
In 500 mL four-necked colben, 24 parts of phthalic acid was charged, and 113 parts of γ-butyrolactone was added and suspended. Thereto, 10 parts of N, N-dimethylaminoethanol and 3 parts of triethylamine were added and stirred until the solution became homogeneous. N, N-dimethylaminoethanol / phthalate / triethylamine / phthalate electrolyte solution (25 wt% ) Was obtained.

Example 6
[Production of N, N-dimethylaminoethanol phthalate / γ-butyrolactone, sulfolane electrolyte]
In 500 mL four-necked colben, 24 parts of phthalic acid was charged, and 83 parts of γ-butyrolactone and 30 parts of sulfolane were added and suspended. Thereto, 13 parts of N, N-dimethylaminoethanol was added and stirred until the solution became homogeneous to obtain 150 parts of an N, N-dimethylaminoethanol / phthalate electrolyte solution (25% by weight).

Comparative Example 1
[Manufacture of triethylamine phthalate electrolyte]
Example 1 except that 12 parts of phthalic acid was used instead of 24 parts of phthalic acid, 10 parts of triethylamine was used instead of 13 parts of N, N-dimethylaminoethanol, and 128 parts of γ-butyrolactone was used instead of 113 parts of γ-butyrolactone. In the same manner, 150 parts of a triethylamine / phthalate electrolyte solution (15% by weight) was obtained.

Comparative Example 2
[Manufacture of triethylamine / phthalate electrolyte (containing additive)]
In 500 mL four-necked colben, 14 parts of phthalic acid was added, and 119 parts of γ-butyrolactone was added and suspended. 9 parts of triethylamine was added thereto and stirred until the solution became homogeneous. Further, 0.75 parts of p-nitrobenzoic acid and 7.5 parts of 4,4-biphenyldithiol were added to obtain 150 parts of a triethylamine / phthalate electrolyte solution (15% by weight).

With respect to the electrolytic solutions of Examples 1 to 6 and Comparative Examples 1 and 2, the swelling of the capacitor, the specific conductivity, and the withstand voltage were measured by the following methods, and the measurement results are shown in Table 1.

Capacitor swell: A winding type chip-type aluminum electrolytic capacitor (rated voltage 6.3 V, capacitance 220 μF, size: φ6.3 mm × L5.8 mm) was prepared using an electrolytic solution. Resin vulcanized butyl rubber was used as the sealing rubber. The heat resistance was evaluated under reflow conditions at a reflow top temperature of 255 ° C. and 230 ° C. for 30 seconds or more, and at 200 ° C. for 70 seconds or more. The reflow was performed twice, and the rubber swelling was measured with a digital caliper to determine the swelling of the capacitor. An evaluation result shows the average of ten measurement results.

Specific conductivity: Specific conductivity at 30 ° C. was measured using a conductivity meter CM-40S manufactured by Toa Denpa Kogyo Co., Ltd.

Withstand voltage: Using a 10 cm ² high-pressure chemical-etched aluminum foil for the anode and a plain 10 cm ² aluminum foil for the cathode, the withstand voltage of the electrolyte was measured at 25 ° C. when a constant current method (2 mA) was applied. .

As is clear from Table 1, Examples 1 to 6 of the present invention showed very little rubber swelling of the product, and showed the same electrical conductivity as that of the prior art.

The electrolytic solution of the present invention can be used for an electrolytic capacitor, and can realize an aluminum electrolytic capacitor that is particularly excellent in reflow characteristics.

Claims (5)

Aluminum electrolysis containing at least one selected from the group consisting of tertiary amine salt (A) represented by general formula (1) and tertiary amine salt (B) represented by general formula (2) Electrolytic solution for capacitors.

[In General Formulas (1) and (2), n, m, and l are integers of 2 or 3, and X ₁ ⁻ and X ₂ ⁻ are a counter anion (b). ] _2. The electrolytic solution according to claim 1, wherein X ₁ ⁻ and X ₂ ^{− in the} general formulas (1) and (2) are carboxylate anions having 1 to 20 carbon atoms. The electrolyte solution according to claim 1 or 2, further comprising an organic solvent (D). The electrolytic solution according to claim 3, wherein the organic solvent (D) is γ-butyrolactone or a mixed solvent containing γ-butyrolactone. The aluminum electrolytic capacitor which uses the electrolyte solution of any one of Claims 1-4.