JP2002217068A - Electrolyte for driving electrolytic capacitor and electrolytic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrolyte for driving an electrolytic capacitor having improved long life at a high temperature and humidity resistance, and the electric capacitor using the electrolyte. SOLUTION: This electrolyte for driving an electrolytic capacitor uses a mixed solvent of sulfolane and an aprotic polarized solvent, the amine salt of phthalic acid or the dissolved substance of amidine salt, and hypophosphite ammonium as essential ingredients, thus achieving stability under high- temperature conditions, and inhibiting chemical reaction to the phthalic acid, and hydration deterioration in an electrode material due to contained water or the penetration of water under moisture-resistant conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for driving an electrolytic capacitor and an electrolytic capacitor using the same.

[0002]

2. Description of the Related Art A general electrolytic capacitor is composed of an anode foil having a dielectric oxide film formed by anodic oxidation on the surface of which the effective surface area is increased by etching an aluminum foil and a cathode foil having an aluminum foil etched. To form a capacitor element, impregnating the capacitor element with a driving electrolyte, and sealing the capacitor element in a metal case.

Various types of driving electrolytes are used depending on the performance of the electrolytic capacitor. For example, a solution obtained by dissolving an ammonium salt of boric acid or adipic acid as a solute in a solvent of ethylene glycol or a solvent of γ-butyrolactone is used. A solution in which an organic acid, an inorganic acid, or a salt thereof is dissolved as a solute is used.

Further, in order to improve high-temperature long-life, moisture resistance, and low-temperature characteristics, an aluminum electrolytic capacitor using an electrolyte in which sulfolane and γ-butyrolactone are used as a solvent and a quaternized imidazolinium salt is dissolved is proposed. (JP-A-11-126732).

[0005]

However, in recent years, the use environment of electronic components used in an engine room has been further increased in temperature in accordance with the improvement of the performance of the vehicle in the field of the vehicle. With the liquid, there is a problem that the electrode material constituting the electrolytic capacitor undergoes a hydration reaction due to the influence of a small amount of water contained inside the electrolytic capacitor and water entering from the outside, resulting in severe deterioration of the characteristics, and the required performance cannot be satisfied. Was.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an electrolytic solution for driving an electrolytic capacitor, which prevents deterioration of electrode materials and has an improved high temperature and long life, and an electrolytic capacitor using the same. Is what you do.

[0007]

In order to achieve the above object, the present invention has the following arrangement.

The invention according to claim 1 of the present invention comprises a mixed solvent of sulfolane and an aprotic polar solvent, a solute containing phthalic acid as an anionic component and an amine salt or amidine salt as a cationic component, It is composed of ammonium phosphite as an essential component. By using a mixed solvent of sulfolane having a high boiling point and an aprotic polar solvent, it is stable under high-temperature conditions and is chemically stable with phthalate. By suppressing the reaction and further adding ammonium hypophosphite, there is an effect that the hydration deterioration of the electrode material due to the contained moisture or the infiltrated moisture under the moisture resistant condition can be suppressed.

Further, since the mixed solvent has a freezing point lowering effect that does not solidify even at -25 ° C. or lower, it is possible to improve the low-temperature conductivity of the electrolytic solution.

According to a second aspect of the present invention, in the first aspect, the mixing ratio of the sulfolane and the aprotic polar solvent is such that the ratio of the aprotic polar solvent to the sulfolane 1 is 0.25. In this range, the stability at high temperature, which is a characteristic of sulfolane, is not impaired, and the freezing point generated by mixing sulfolane and an aprotic polar solvent is maintained. The lowering effect has an effect that a high electrical conductivity that does not solidify even at a low temperature of −25 ° C. or less can be obtained.

The mixing ratio of the mixed solvent is sulfolane 1
On the other hand, if the aprotic polar solvent is less than 0.25, the temperature of the freezing point of the mixed solvent increases, which is not preferable. On the other hand, if the amount of the aprotic polar solvent with respect to sulfolane 1 exceeds 4.0, the stability of sulfolane at high temperatures is impaired, which is not preferable.

According to a third aspect of the present invention, in the first aspect, ammonium hypophosphite is contained in an amount of 0.1 to 0.1.
The water resistance of the electrode material can be improved by containing 0.1% by weight or more of ammonium hypophosphite. It has the effect of suppressing hydration deterioration of the material.

Further, even if the moisture content is increased by performing a long-term test under high temperature and humidity resistance conditions, the dissociation of ammonium hypophosphite is promoted due to the presence of the ammonium salt, and the water resistance of the electrode material is further improved. I do.

The amount of ammonium hypophosphite is 5 wt%.
Exceeding the range is not preferable because the dissolution of the electrode material becomes severe and leads to deterioration of characteristics.

According to a fourth aspect of the present invention, in the first aspect, the amine salt or the amidine salt is a tertiary amine salt, a compound having an alkyl-substituted amidine group, or a compound having an alkyl-substituted amidine group. It has at least one kind selected from the group consisting of quaternary salts of compounds, and has the effect of suppressing the occurrence of liquid leakage from the sealing portion by this structure.

According to a fifth aspect of the present invention, the quaternary salt of the compound having an alkyl-substituted amidine group is an imidazole compound, a benzimidazole compound, an alicyclic amidine compound (pyrimidine). Compound, imidazoline compound), which suppresses the occurrence of liquid leakage from the sealing portion and has a higher vapor pressure than the tertiary amine. This has the effect that the product characteristics are stable and low impedance can be achieved.

According to a sixth aspect of the present invention, there is provided an elastomer comprising a peroxide-cured and / or resin-cured butyl rubber, wherein at least a part of the elastic body has a hardness of 75 IRH.
An electrolytic capacitor using a sealing body of D (international rubber hardness unit) or more and the electrolytic solution for driving an electrolytic capacitor according to claim 1. Since the stopping power does not decrease, it is possible to prevent water from entering from the lead wire portion even under high temperature and high humidity, and to obtain a highly reliable electrolytic capacitor capable of suppressing a change in characteristics. In addition, by setting the hardness of at least a part of the elastic body to 75 IRHD (international rubber hardness unit) or more, it is possible to suppress the appearance deformation of the sealing surface, which tends to occur when the internal pressure increases, with physical strength. As a result, deformation of the appearance of the electrolytic capacitor can be suppressed, and thus, soldering defects during mounting can be further improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrolytic capacitor according to the present invention has the same configuration as a conventional electrode capacitor. That is,
A capacitor element is formed by winding an anode foil in which a dielectric oxide film layer is formed by anodic oxidation on a surface in which an effective surface area is enlarged by etching an aluminum foil and a cathode foil in which an aluminum foil is etched through a separator. The capacitor element is impregnated with a driving electrolyte, and the capacitor element is inserted into a metal case and sealed with a sealing body.

The driving electrolyte contains essential components of a mixed solvent of sulfolane and an aprotic polar solvent, a solute of an amine salt or an amidine salt of phthalic acid, and ammonium hypophosphite. Further, another solvent may be added to the driving electrolyte.

The aprotic polar solvent is an amide [N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N- Dimethylacetamide, etc.), lactones [γ-butyrolactone,
α-valerolactone, γ-valerolactone, etc.], cyclic amide type [ethylene carbonate, propylene carbonate, etc.], nitrile type [acetonitrile, etc.], oxide type [dimethylsulfoxide, etc.], imidazolidinone type [3]
-Methyl-1,3-oxazolidin-2-one, 1,3
-Diethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, 1-methyl-3-ethyl-
2-imidazolidinone, 1,3,4-trimethyl-2-
Imidazolidinone, 1,3,4,5-tetramethyl-2
—Imidazolidinone and the like].

Of these, lactones are preferred, and γ-butyrolactone is particularly excellent in terms of high-temperature life and high conductivity.

Other solvents to be mixed with the driving electrolyte include alcohols [methanol, ethanol, propanol, butanol, cyclobutanol, cyclohexanol, ethylene glycol, propylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxy Propylene glycol].
As the aprotic organic solvent, amide-based [N
-Methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, etc.], lactones [α-valerolactone, γ
Valerolactone etc.), cyclic amide type [ethylene carbonate, propylene carbonate etc.], nitrile type [acetonitrile etc.], oxide type [dimethylsulfoxide etc.], imidazolidinone type [3-methyl-1,3-oxazolidin-2- On, 1,3-diethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone,
1,3,4-trimethyl-2-imidazolidinone, 1,
3,4,5-tetramethyl-2-imidazolidinone and the like]
It is.

The solute contains phthalic acid as an anion component,
It has an amine salt or an amidine salt as a cation component, and has high conductivity and is thermally stable.

The amine salt is preferably a tertiary amine salt. Examples thereof include trialkylamines [trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl n-propylamine, dimethylisopropylamine, methylethyl n-propylamine, methylethyl Ethyl isopropylamine, diethyl n-propylamine, diethylisopropylamine, tri-n-
Propylamine, triisopropylamine, tri-n-butylamine, tritert-butylamine, etc.] phenyl group-containing amine [dimethylphenylamine, methylethylphenylamine, diethylphenylamine, etc.].

Of these, preferred are trialkylamines having high conductivity, and more preferred are trimethylamine, dimethylethylamine, methyldiethylamine, and the like.
At least one selected from the group consisting of triethylamine.

The above amidine salt is preferably a compound having an alkyl-substituted amidine group or a quaternary salt of a compound having an alkyl-substituted amidine group, and the compound having an alkyl-substituted amidine group is preferably an imidazole compound, a benzimidazole compound, or an alicyclic amidine compound. (Pyrimidine compounds, imidazoline compounds). In particular,
1,8-diazabicyclo [5,4,0] undecene-7,1,5- having high conductivity and excellent impedance performance
Diazabicyclo [4,3,0] nonene-5,1,2-dimethylimidazolinium, 1,2,4-trimethylimidazoline, 1-methyl-2-ethyl-imidazoline,
1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-heptylimidazoline, 1-methyl-2-
(3 ′ heptyl) imidazoline, 1-methyl-2-dodecyl imidazoline, 1,2-dimethyl-1,4,5,6
-Tetrahydropyrimidine, 1-methylimidazole,
1-Methylbenzimidazole is preferred.

The quaternary salt of the compound having an alkyl-substituted amidine group includes imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds quaternized with an alkyl or arylalkyl group having 1 to 11 carbon atoms. Pyrimidine compounds and imidazoline compounds). Specifically, 1-methyl-1,8-diazabicyclo [5,4,0] undecene-7, 1-methyl-1,5-
Diazabicyclo [4,3,0] nonene-5,1,2,3
-Trimethylimidazolinium, 1,2,3,4-tetramethylmidazolinium, 1,2-dimethyl-3-ethyl-imidazolinium, 1,3,4-trimethyl-2-
Ethyl imidazolinium, 1,3-dimethyl-2-heptyl imidazolinium, 1,3-dimethyl-2- (3 ′
Heptyl) imidazolinium, 1,3-dimethyl-2-
Dodecyl imidazolinium, 1,2,3-trimethyl-
1,4,5,6-tetrahydropyrimidium, 1,3-
Dimethylimidazolium, 1-methyl-3-ethylimidazolium, and 1,3-dimethylbenzimidazolium are preferable, and an electrolytic capacitor having high conductivity and excellent impedance performance can be provided.

The content of the solute in the driving electrolyte is usually from 10 to 95% by weight, preferably from 20 to 90% by weight, based on the weight of the driving electrolyte. Outside this range, the electrical conductivity is significantly reduced, which is not preferable.

In order to improve the spark voltage of the driving electrolyte, phosphorus compounds [phosphoric acid, phosphoric acid ester, etc.], boric acid compounds [boric acid, boric acid and polysaccharides (mannitol, sorbit, etc.)) Complex compounds with boric acid and polyhydric alcohols (ethylene glycol, glycerin, etc.)]
And a nitro compound [o-nitrobenzoic acid, m
-Nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol, p-nitrophenol and the like].

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

Table 1 shows the compositions of the driving electrolytes of Examples 1 to 6 and Comparative Example 1.

[0032]

[Table 1]

An electrolytic capacitor (rated voltage: 6.3V, using the driving electrolyte solutions of Examples 1 to 6 and Comparative Example 1)
Capacitance 1200 μF, size: φ10 mm × L12.
5 mm). At this time, a butyl rubber of peroxide peroxide (hardness: 75 IRHD) was used for the sealing body.

The results of testing this electrolytic capacitor under high temperature and high humidity conditions are shown in Table 2. The high-temperature and high-humidity conditions were a load at 5% water and a temperature of 125 ° C.

[0035]

[Table 2]

As is clear from Table 2, since the electrolytic capacitor of Comparative Example 1 did not contain ammonium hypophosphite, the characteristic change became very large after a long time. On the other hand, since the electrolytic capacitors of Examples 1 to 6 contain ammonium hypophosphite, there is little change in characteristics, and sufficient reliability can be ensured even under high temperature and high humidity conditions.

The mixed solvent of sulfolane and γ-butyrolactone, which is an aprotic polar solvent, causes little change in characteristics under high-temperature and high-humidity conditions, but reduces the mixing ratio of sulfolane and γ-butyrolactone. By setting γ-butyrolactone in the range of 0.25 to 4.0 with respect to sulfolane 1, more reliable characteristics can be obtained.

Next, the compositions of the driving electrolyte solutions of Examples 7 to 13 are shown in Table 3.

[0039]

[Table 3]

An electrolytic capacitor (rated voltage of 6.3 V, capacitance of 12
00 μF, size: φ10 mm × L12.5 mm). At this time, a butyl rubber of peroxide peroxide (hardness: 75 IRHD) was used for the sealing body.

The results of testing this electrolytic capacitor under high temperature and high humidity conditions are shown in Table 4. The high-temperature and high-humidity conditions were a load at 5% water and a temperature of 125 ° C.

[0042]

[Table 4]

As is clear from Table 4, by setting the amount of ammonium hypophosphite in the range of 0.1 to 5.0 wt%, the water resistance of the electrode material can be improved. It is possible to obtain a highly reliable electrolytic capacitor with little change in characteristics under the conditions.

The 1,3-diethyl-2 used for the solvent
-Instead of imidazolidinone, lactones α-
Valerolactone, γ-valerolactone, or imidazolidinone-based 3-methyl-1,3-oxazolidin-2-one, 1,3-dipropyl-2-imidazolidinone, 1-methyl-3-ethyl- 2-imidazolidinone, 1,3,4-trimethyl-2-imidazolidinone,
Even when an electrolytic capacitor using 1,3,4,5-tetramethyl-2-imidazolidinone is manufactured and tested under high temperature and high humidity conditions, characteristics equivalent to those of the electrolytic capacitors of Examples 7 to 13 are obtained. be able to.

In place of the dimethylethylammonium phthalate used for the solute, trimethylamine of phthalic acid, dimethylethylamine, methyldiethylamine, triethylamine or 1,2-dimethylimidazolinium of phthalic acid, 1,2,4-trimethyl Imidazoline,
1-methyl-2-ethyl-imidazoline, 1,4-dimethyl-2-ethylimidazoline, and phthalic acid
2-dimethyl-3-ethyl-imidazolinium, 1,
3,4-trimethyl-2-ethylimidazolinium,
Even if an electrolytic capacitor using any of 1,3-dimethyl-2-heptylimidazolinium is manufactured and tested under high-temperature and high-humidity conditions, characteristics equivalent to those of the electrolytic capacitors of Examples 7 to 13 are obtained. Can be.

[0046]

As described above, the electrolytic solution for driving an electrolytic capacitor of the present invention comprises a mixed solvent of sulfolane and an aprotic polar solvent, phthalic acid as an anionic component, and an amine salt or amidine salt as a cationic component. A composition that contains ammonium hypophosphite as an essential component, and contains ammonium hypophosphite, so that there is little deterioration in characteristics under high-temperature and high-humidity conditions and a highly reliable drive for electrolytic capacitors It is an electrolytic solution, and an electrolytic capacitor using the same can guarantee a high temperature and a long life.

Claims (6)

[Claims] 1. A mixed solvent of sulfolane and an aprotic polar solvent, a solute containing phthalic acid as an anionic component and an amine salt or amidine salt as a cationic component, and ammonium hypophosphite as essential components. Electrolyte for driving electrolytic capacitors. 2. The electrolytic capacitor according to claim 1, wherein the mixing ratio of the sulfolane and the aprotic polar solvent is in the range of 0.25 to 4.0 for the aprotic polar solvent with respect to sulfolane 1. Driving electrolyte. 3. The method according to claim 1, wherein the ammonium hypophosphite is 0.1 to 5.
The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the electrolytic solution is in a range of 0 wt%. 4. The amine salt or amidine salt is at least one selected from the group consisting of a tertiary amine salt, a compound having an alkyl-substituted amidine group, and a quaternary salt of a compound having an alkyl-substituted amidine group. 2. The electrolytic solution for driving an electrolytic capacitor according to 1. 5. The quaternary salt of a compound having an alkyl-substituted amidine group is at least one selected from the group consisting of imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds). 3. The electrolytic solution for driving an electrolytic capacitor according to item 1. 6. A sealing body comprising an elastic body of peroxide-vulcanized and / or resin-vulcanized butyl rubber, wherein at least a part of the elastic body has a hardness of at least 75 IRHD (international rubber hardness unit). 5. An electrolytic capacitor using the electrolytic solution for driving an electrolytic capacitor according to any one of 5.