JP6487285B2 - Composition for gel electrolyte and gel electrolyte and electrolytic capacitor using the same - Google Patents

Description

  The present invention relates to a composition for gel electrolyte, a gel electrolyte using the composition, and an electrolytic capacitor.

  When an electrolytic capacitor using an electrolytic solution as an electrolyte is used at a high temperature, there is a tendency that deterioration of electrical characteristics such as a decrease in capacity due to dry-up of the electrolytic solution easily occurs. Moreover, the electrolyte is gasified by sudden heat, and the internal pressure increases, which may cause the capacitor to burst or leak.

  Thus, as means for preventing liquid leakage, a method of adding a reactive polymer to the electrolytic solution to gel or solidify, a method of impregnating a polymer sheet with the electrolytic solution, and the like are known. For example, in Patent Document 1, a copolymer having an amide skeleton and a monomer having a reactive group is used as an electrolyte solution-solidifying copolymer that is added to the electrolyte solution to gel or solidify the electrolyte solution. A polymer is disclosed. Further, in Patent Document 2, an electrolytic capacitor drive composed of a polyhydric alcohol solvent having a specific molecular weight, an electrolyte salt, a polymer containing an acid group in the molecule, and a polymer salt made of an amine compound. A solid polymer electrolyte is disclosed.

JP-A-11-106440 Japanese Patent Laid-Open No. 5-175083

  However, since the monomer constituting the gelling agent described in Patent Document 1 has an amide skeleton, the viscosity of the electrolyte solution may increase due to the skeleton attracting each other by hydrogen bonding. As a result, the impregnation property of the capacitor element into the oxide film pores may be reduced, leading to a reduction in the capacitance of the capacitor. In addition, when a gel skeleton is formed using the gelling agent described in Patent Document 2 and the electrolytic solution is gelled, water is generated as a by-product during the cross-linking reaction, and heat resistance and low-temperature characteristics are reduced. May invite.

  An object of the present invention is to provide a highly reliable electrolytic capacitor that suppresses deterioration of electrical characteristics at high temperatures, rupture of the capacitor due to gasification of the electrolytic solution, and liquid leakage.

  In order to solve the above problems, the present invention provides an electrolyte solution and a gel electrolyte having a gel skeleton in which a compound having a carboxyl group and not containing a nitrogen atom in the main chain skeleton and a compound having an oxazoline group are bonded by a covalent bond. Specifically, it is characterized by having the following configuration.

  1. A composition for a gel electrolyte comprising an electrolytic solution and a gelling agent, wherein the gelling agent does not contain a nitrogen atom in the main chain skeleton and has a carboxyl group, and a compound B having an oxazoline group And a composition for gel electrolyte, comprising:

  2. 2. The gel electrolyte composition according to 1 above, wherein the compound A has a molecular weight of 50,000 or less.

  3. The content ratio of the compound A and the compound B is a value obtained by dividing the number of moles of the carboxyl group of the compound A by the number of moles of the oxazoline group of the compound B is 1.5 or more and 2.5 or less. 3. The gel electrolyte composition as described in 1 or 2 above.

  4). 4. The composition for gel electrolyte according to any one of 1 to 3, wherein the compound A is polyacrylic acid.

  5. A gel electrolyte formed by gelling the composition for gel electrolyte according to any one of 1 to 4 above.

  6). 6. An electrolytic capacitor comprising an electrolyte layer containing the gel electrolyte as described in 5 above.

  7). 7. The electrolytic capacitor as described in 6 above, further comprising a conductive polymer in the electrolyte layer.

  According to the present invention, a gel skeleton is formed by a covalent bond between a compound having a carboxyl group without containing a nitrogen atom in the main chain skeleton and a compound having an oxazoline group, and the electrolytic solution is retained in the gel skeleton. By gelling, a chemical gel electrolyte that is strong and excellent in heat resistance can be obtained. In the present invention, the use of a compound having an oxazoline group is advantageous because a gel skeleton can be formed by a crosslinking reaction without generating water as a by-product as described above.

  Moreover, since the vapor pressure can be lowered by using the gel electrolyte of the present invention, it is possible to suppress dry-up that causes deterioration of electrical characteristics over time or at high temperatures. Furthermore, since rapid gasification can be suppressed, the capacitor can be prevented from rupturing or leaking when exposed to a high temperature due to reflow or heat generation inside the capacitor. As described above, according to the present invention, a highly reliable electrolytic capacitor can be provided.

It is a typical sectional view showing the structure of the electrolytic capacitor concerning one embodiment of the present invention. It is a typical sectional view showing the structure of the electrolytic capacitor concerning one embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to these embodiments.

  The composition for a gel electrolyte according to the present invention includes an electrolytic solution and a gelling agent, and the gelling agent does not contain a nitrogen atom in the main chain skeleton and has a carboxyl group (hereinafter referred to as “Compound A”). And a compound having an oxazoline group (hereinafter also referred to as “compound B”). Moreover, the gel electrolyte of this invention is obtained by gelatinizing the said composition for gel electrolytes. The gel electrolyte is obtained by holding the electrolytic solution in a gel skeleton formed by a covalent bond between a carboxyl group in compound A and an oxazoline group in compound B.

  An electrolytic capacitor according to an embodiment of the present invention includes a valve metal, a dielectric layer formed on a surface of the valve metal, and an electrolyte layer formed on the dielectric layer. . The electrolyte layer contains the gel electrolyte. Hereinafter, the gel electrolyte according to the present embodiment and an electrolytic capacitor using the gel electrolyte will be described in detail.

<Gel electrolyte>
As described above, the gel electrolyte according to the present invention includes an electrolytic solution and a gelling agent.

[Electrolyte]
The electrolytic solution is obtained by dissolving an electrolyte in an organic solvent.

(Organic solvent)
It does not specifically limit as an organic solvent, It selects from a protic polar solvent and an aprotic polar solvent. For example, alcohol solvents such as ethylene glycol, propylene glycol, glycerin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl Ether solvents such as ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and polyethylene glycol; N-methylformamide, N-ethylformamide, N, N-dimethylformamide, N, N-diethylformamide, N −Me Amide solvents such as lucacetamide, N-ethylacetamide, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylpropionamide, N-methylpyrrolidone, N-ethylpyrrolidone; γ-butyrolactone, β- Lactone solvents such as butyrolactone, γ-valerolactone, δ-valerolactone, α-acetyl-γ-butyrolactone; carbonate solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate; acetonitrile, propionitrile, butyronitrile, acrylonitrile, Nitrile solvents such as methacrylonitrile, benzonitrile, 3-methoxypropionitrile; carbamate solvents such as N-methyl-2-oxazolidone; N, N′-dimethylimidazolidinone, etc. And urea solvents such as sulfolane, 3-methylsulfolane, dimethyl sulfone, and the like. These may be used alone or in combination of two or more.

  Among the above organic solvents, ethylene glycol, propylene glycol, glycerin, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyethylene glycol, N-methylformamide, N-ethylformamide, N-methylacetamide N, N-diethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, α-acetyl-γ-butyrolactone, ethylene carbonate, propylene carbonate, benzonitrile, N , N'-dimethylimidazolidinone, sulfolane, and dimethyl sulfone have high boiling points and are volatile even when gelled. Since it becomes low, it is preferable.

  Further, ethylene glycol, propylene glycol, glycerin, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, N-methylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, propylene carbonate, and benzonitrile are 0. It is particularly preferable because it is liquid even at a temperature of ℃ or lower. The melting point of glycerin is 17.8 ° C. under atmospheric pressure, but 17.8 ° C. unless seed crystals are contained or unless the temperature is gradually raised after cooling to about −75 ° C. Even if it is below ℃, it does not freeze.

(Electrolytes)
As an electrolyte for forming an electrolyte solution in addition to an organic solvent, inorganic acids and organic acid ammonium salts, amine salts, quaternary ammonium salts, quaternary phosphonium salts, and the like can be used. Here, as the inorganic acid, boric acid, carbonic acid, silicic acid, phosphoric acid, phosphorous acid, hypophosphorous acid, nitric acid, sulfuric acid, sulfurous acid, thiocyanic acid, cyanic acid, borohydrofluoric acid, hydrofluoric acid, Examples thereof include arsenic hydrofluoric acid, antimony hydrofluoric acid, perchloric acid and the like. Organic acids include formic acid, acetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecane Diacid, pentadecanedioic acid, dimethylmalonic acid, diethylmalonic acid, dipropylmalonic acid, 3,3-dimethylglutaric acid, 3-methyladipic acid, 1,6-decanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, Maleic acid, citraconic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, salicylic acid, γ-resorcinic acid, p-nitrobenzoic acid, phenol, picric acid, methanesulfonic acid, benzenesulfonic acid, trifluoromethanesulfonic acid Etc. A part of the inorganic acid or organic acid may be esterified.

  Examples of the amine include methylamine, ethylamine, propylamine, butylamine, ethylenediamine, monoethanolamine, dimethylamine, diethylamine, dipropylamine, ethylmethylamine, diphenylamine, diethanolamine, trimethylamine, triethylamine, tributylamine, 1,8-diazabicyclo [ 5.4.0] -undecene-7, triethanolamine and the like.

  As quaternary ammonium, diethylammonium, triethylammonium, tripropylammonium, ethanolammonium, diethanolammonium, triethanolammonium, cyclohexylammonium, piperidinium, 1,5-diazabicyclo [4.3.0] nonenium-5, 1,8 -Diazabicyclo [5.4.0] undecenium-7, tetramethylammonium, methyltriethylammonium, dimethyldiethylammonium, trimethylethylammonium, tetraethylammonium, tetrabutylammonium, N, N-dimethylpyrrolidinium, N-methyl-N -Ethylpyrrolidinium, N, N-dimethylpiperidinium, benzyltrimethylammonium, N-ethylpyridinium, N, N'-di Chill imidazolium and the like. Examples of the quaternary phosphonium include tetramethylphosphonium, methyltriethylphosphonium, tetraethylphosphonium, tetrapropylphosphonium, tetrabutylphosphonium and the like.

  The electrolyte may be used alone or in combination of two or more. Moreover, it is preferable that the boric acid or boric acid ester is contained from the point which can provide a flame retardance.

[Gelling agent]
The gelling agent used in the present invention contains Compound A and Compound B. In gelling the composition for gel electrolyte of the present invention, a gel skeleton is formed by covalently bonding a carboxyl group contained in Compound A and an oxazoline group contained in Compound B.

(Compound A: Compound having no carboxyl atom in the main chain skeleton and having a carboxyl group)
In the present specification, the “main chain skeleton” in a compound having a carboxyl group without containing a nitrogen atom in the main chain skeleton is a part constituting the skeleton of the compound, and a substituent bonded to the skeleton. It means the part excluding atoms. That is, for example, when Compound A is polyacrylic acid, an alkyl chain containing carbon substituted with a carboxyl group is a main chain skeleton. The compound A is preferably one having two or more carboxyl groups. Examples of the compound having two or more carboxyl groups include oxalic acid, malonic acid, maleic acid, succinic acid, glutamic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, orthophthalic acid, isophthalic acid, terephthalic acid Acid, citric acid, isocitric acid, tartronic acid, fumaric acid, malic acid, tartaric acid, monomolecular polycarboxylic acid such as meso-butane-1,2,3,4-tetracarboxylic acid, polyacrylic acid, etc. Polycarboxylic acid is mentioned. These may be used alone or in combination of two or more. From the viewpoint of easy retention of the electrolytic solution in the gel skeleton, it is preferable that there are more carboxyl groups, and polycarboxylic acids such as polyacrylic acid are particularly preferable.

  As the compound A, those having a molecular weight of 100,000 or less are preferably used. The molecular weight of Compound A is preferably 50,000 or less, and more preferably 5,000 or more and 50,000 or less. When the molecular weight is greater than 100,000, the viscosity of the electrolyte before gelation increases, and the impregnation property of the gel electrolyte into the oxide film pores decreases, resulting in a decrease in capacity.

  Moreover, it is preferable that the addition amount of the compound A is 5 mass parts or more and less than 15 mass parts with respect to 100 mass parts of electrolyte solution. When the amount of compound A added is less than 5 parts by mass, gelation becomes insufficient, and when it is 15 parts by mass or more, the conductivity of the gel electrolyte decreases and the equivalent series resistance (ESR) of the capacitor increases. To do.

(Compound B: Compound having an oxazoline group)
Compound B functions as a crosslinking agent that crosslinks the oxazoline group in compound B and the carboxyl group in compound A via a covalent bond. As the compound B, for example, Epocros (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.) and the like are preferably used. Specific examples include “Epocross” (registered trademark) product numbers K-2010E, K-2020E, K-2030E, WS-300, WS-500, WS-700, and the like. These may be used alone or in combination of two or more. Compound B preferably has a plurality of oxazoline groups per molecule. When a compound that does not have a plurality of oxazoline groups per molecule is used, it is difficult to form a gel skeleton.

  In addition, commercially available compound B may contain a lot of moisture, and if added to the electrolyte as it is, the volatility and low temperature characteristics of the prepared gel electrolyte may deteriorate due to the moisture. Therefore, when adding commercially available compound B to the electrolytic solution, the solvent used for the electrolytic solution is added to compound B in an amount equal to the water in compound B and heated at 100 ° C. or higher in advance. It is preferable to carry out an operation of substituting the water in Compound B with the solvent used for the electrolyte.

  In Compound B, the value obtained by dividing the number of moles of the carboxyl group of Compound A by the number of moles of the oxazoline group of Compound B (hereinafter referred to as “the number of carboxyl groups of Compound A / the number of oxazoline groups of Compound B”) is 1. It is preferable to add so that it may become 5 or more and 2.5 or less. When the above value is smaller than 1.5, the number of unreacted carboxyl groups decreases, and the liquid retaining property of the electrolytic solution becomes insufficient. Moreover, when said value is larger than 2.5, reaction of an oxazoline group and a carboxyl group required in order to form a gel frame | skeleton will decrease, and gelation will become inadequate.

  Next, a method for producing a gel electrolyte will be described. The gel electrolyte is obtained by adding Compound A and Compound B, which are gelling agents, to the electrolytic solution, and heating to 60 ° C. or higher where the crosslinking reaction starts to gel. As a result of the covalent bond between the carboxyl group of compound A and the oxazoline group of compound B by the cross-linking reaction, a gel skeleton is formed, and an electrolyte is held in the skeleton to obtain a gel electrolyte.

  The gel electrolyte obtained as described above is used as an electrolyte layer of an electrolytic capacitor. In addition to the gel electrolyte, the electrolyte layer may contain a conductive polymer.

[Conductive polymer]
Examples of the conductive polymer include polypyrrole, polythiophene, polyaniline, and derivatives thereof. Among these, poly (3,4-ethylenedioxythiophene) or a derivative thereof is preferable. The conductive polymer may be a homopolymer or a copolymer. Moreover, 1 type may be used independently and 2 or more types may be used together.

  Examples of the conductive polymer dopant include alkylsulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, anthraquinonesulfonic acid, camphorsulfonic acid, polyacrylic acid, polystyrenesulfonic acid, and derivatives thereof. These sulfonic acids may be monosulfonic acid, disulfonic acid or trisulfonic acid.

  Examples of alkylsulfonic acid derivatives include 2-acrylamido-2-methylpropanesulfonic acid. Examples of benzenesulfonic acid derivatives include phenolsulfonic acid, styrenesulfonic acid, toluenesulfonic acid, and dodecylbenzenesulfonic acid. Examples of naphthalene sulfonic acid derivatives include 1-naphthalene sulfonic acid, 2-naphthalene sulfonic acid, 1,3-naphthalene disulfonic acid, 1,3,6-naphthalene trisulfonic acid, and 6-ethyl-1-naphthalene sulfonic acid. It is done. Examples of the derivatives of anthraquinone sulfonic acid include anthraquinone-1-sulfonic acid, anthraquinone-2-sulfonic acid, anthraquinone-2,6-disulfonic acid, and 2-methylanthraquinone-6-sulfonic acid.

  Among these, toluenesulfonic acid such as p-toluenesulfonic acid and polystyrenesulfonic acid are preferable. When poly (3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid is used, a suspension that is stably dispersed in an aqueous solvent is obtained. Moreover, it is known that the conductive polymer composition obtained from the suspension has high conductivity.

<Electrolytic capacitor>
Then, the structure of the electrolytic capacitor of this invention is demonstrated. The electrolytic capacitor of the present invention contains the gel electrolyte as an electrolyte layer. The basic configuration of the electrolytic capacitor is the same as that of the conventional one, and a known shape, material, etc. can be adopted without particular limitation.

  As shown in FIG. 1, an electrolytic capacitor according to an embodiment of the present invention includes, for example, an anode body 1 made of a valve metal and a dielectric made of an oxide film formed by anodizing the surface of the anode body 1. It comprises a layer 2, a cathode body 3 made of a valve metal such as aluminum which has been expanded by etching, a winding element made of a separator 5, and a gel electrolyte 4 impregnated in the winding element.

  The anode body 1 is formed of a valve metal plate, foil, or wire; a sintered body made of fine particles of the valve metal; a porous metal that has been subjected to surface expansion by etching, or the like. As the valve action metal, it is preferable to use aluminum, tantalum, niobium, titanium, zirconium, hafnium, tungsten, and alloys thereof.

  The separator is a sheet that physically blocks the contact between the anode and the cathode, and the sheet has a hole through which ions in the electrolytic solution can pass. A general separator can be used as the separator, and is not particularly limited. Examples thereof include paper separators such as manila paper and kraft paper, polyolefin separators such as polypropylene and polyethylene, engineering plastic separators such as polyphenylene sulfide and polybutylene terephthalate, and cellulose-based separators.

  The electrolytic capacitor of the present invention can be manufactured by a known method. For example, an anode foil made of aluminum whose surface is anodized and made dielectric, an aluminum cathode foil facing the dielectric surface of the anode foil, and the anode foil and the cathode foil are interposed A wound element formed of a separator and impregnated with the gel electrolyte can be manufactured by sealing in a case.

  As a method for forming a gel electrolyte on the wound element, first, the compound A and the compound B (the operation in which water was replaced with a solvent of the electrolyte solution in advance) were added to the electrolyte solution. A solution (this solution containing a gelling agent and an electrolytic solution (a composition for gel electrolyte) is used as a pregel electrolytic solution) is prepared. Subsequently, the pregel electrolyte is impregnated in the wound element at 60 ° C. to 80 ° C. for 1 hour or longer, and the pregel electrolyte is infiltrated into the wound element. Next, the gel electrolyte is formed by heating at 100 ° C. to 160 ° C.

  In addition, when impregnating a winding element with the said pregel electrolyte solution, you may add simultaneously the solution containing the said conductive polymer to a pregel electrolyte solution. Further, the conductive polymer may be formed on the winding element before the winding element is impregnated with the pregel electrolyte. The conductive polymer may be formed by chemical oxidation polymerization of a monomer that provides the conductive polymer on the dielectric layer, or may be formed by drying using a conductive polymer solution. Through such a process, an electrolyte layer containing both the conductive polymer and the gel electrolyte is obtained.

  Further, as shown in FIG. 2, the electrolytic capacitor of the present invention has an anode body 1 made of a valve metal such as aluminum, tantalum, or niobium, and a dielectric layer 2 formed by anodizing the anode body. Alternatively, a solid electrolytic capacitor produced by sequentially forming a conductive polymer layer 6, a solid electrolyte layer composed of the gel electrolyte 4, a graphite layer 7, and a silver layer 8 may be used. The gel electrolyte 4 is present in a porous hole of the conductive polymer layer 6 and extends right above the dielectric layer 2. Note that the conductive polymer layer 6 may have a multilayer structure including the first conductive polymer layer 6A and the second conductive polymer layer 6B.

  The method for forming the solid electrolyte layer is not particularly limited. For example, a conductive polymer made of a conductive polymer is obtained by performing chemical oxidation polymerization of a monomer that gives a conductive polymer a plurality of times on the dielectric layer. After forming the layer, the conductive polymer layer can be impregnated with the pregel electrolyte and heated to be gelled. The conductive polymer layer may be formed by drying using a conductive polymer solution. In addition, a solid electrolyte layer made of a conductive polymer and a gel electrolyte may be formed by impregnating and heating a mixed solution of a conductive polymer solution and the pregel electrolyte on the dielectric layer. By undergoing such a process, a solid electrolyte layer containing both the conductive polymer and the gel electrolyte is obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited only to these Examples.

[Example 1]
(Preparation of electrolyte)
To 100 parts by mass of ethylene glycol, 30 parts by mass of boric acid and 3.64 parts by mass of aqueous ammonia were mixed and heated at 130 ° C. for 1 hour to prepare an electrolytic solution.

(Pregel electrolyte solution preparation)
Polyacrylic acid (molecular weight 5,000) was used as compound A, and “Epocross (registered trademark) WS-700” (manufactured by Nippon Shokubai Co., Ltd., hereinafter referred to as WS-700) was used as compound B. The following operations were performed before adding WS-700 to the electrolyte. In addition, operation which substitutes the water | moisture content of the compound B was performed in all the Examples and the comparative examples below.
Since WS-700, 100 parts by mass contains 25 parts by mass of solids and 75 parts by mass of water, 75 parts of ethylene glycol, which is a solvent for the electrolytic solution, is added to 100 parts by mass of WS-700. The water in WS-700 was replaced with ethylene glycol by adding part by mass and heating at 125 ° C. for 3 hours.
Here, the mole number of oxazoline groups per gram of WS-700 is 4.5 mmol / g, and the mole number of carboxyl groups per gram of polyacrylic acid (molecular weight 5,000) is 13.8 mmol / g. .

  To 100 parts by mass of the electrolytic solution prepared above, 5 parts by mass of polyacrylic acid (molecular weight 5,000) and WS-700 in which the above water was replaced with ethylene glycol were added in an amount of 10.22 parts by mass in terms of solid content. A pregel electrolyte was prepared.

(Manufacture and evaluation of capacitor elements)
An anode body having an aluminum dielectric layer obtained by anodizing a surface-enlarged aluminum foil by etching, a cathode body made of aluminum that has been surface-enhanced by etching, and a separator were wound to produce a wound element. Thereafter, the wound element was impregnated with the above pregel electrolyte, held at 80 ° C. for 1 hour, and then heated at 125 ° C. for 20 minutes. Thus, a gel electrolyte layer was formed on the wound element, and a capacitor element was manufactured. The manufactured capacitor was evaluated as follows to calculate the capacity appearance rate, the capacity change rate, and the capacitor failure rate. The results are shown in Table 1.

The capacity of the manufactured capacitor was measured with an LCR meter (manufactured by Agilent, E4980A), and the capacity appearance rate was calculated from the following formula.
Capacity appearance rate (%) = (actually measured capacity / wet capacity) × 100
The wet capacity is an electrostatic capacity measured by an LCR meter after immersing the anode body in an aqueous solution of ammonium adipate.

The manufactured capacitor was subjected to a heat resistance test at 150 ° C. for 1000 hours. The capacity immediately after the evaluation (0 hours) and after 1000 hours was measured with an LCR meter, and the change rate of the capacity after 1000 hours was calculated from the following equation.
Capacity change rate (%) = (value after 1000 hours / value after 0 hours) × 100

Furthermore, a voltage application test (1.0 W.V) was performed for 1000 hours on the manufactured capacitor element at 150 ° C., and the capacitor failure rate was evaluated from the following equation. The number of evaluation samples was 100. W.V means the rated product voltage.
Capacitor failure rate (%) = (Liquid leakage, number of damaged samples / number of all evaluation samples) x 100

[Example 2]
A capacitor element was manufactured in the same manner as in Example 1 except that WS-700 was added in an amount of 7.67 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 3]
A capacitor element was manufactured in the same manner as in Example 1 except that WS-700 was added in an amount of 6.13 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 4]
As compound B, “Epocross (registered trademark) WS-500” (manufactured by Nippon Shokubai Co., Ltd., hereinafter referred to as WS-500) (the number of moles of oxazoline group per 1 g is 4.5 mmol / g) in terms of solid content is 10 A capacitor element was manufactured in the same manner as in Example 1 except that .22 parts by mass was added. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 5]
A capacitor element was manufactured in the same manner as in Example 4 except that WS-500 was added in an amount of 7.67 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 6]
A capacitor element was manufactured in the same manner as in Example 4 except that WS-500 was added in an amount of 6.13 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 7]
As compound B, “Epocross (registered trademark) WS-300” (manufactured by Nippon Shokubai Co., Ltd., hereinafter referred to as WS-300) (the number of moles of oxazoline group per gram is 7.7 mmol / g) is 5 in terms of solid content. A capacitor element was manufactured in the same manner as in Example 1 except that 97 parts by mass was added. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 8]
A capacitor element was manufactured in the same manner as in Example 7 except that WS-300 was added in an amount of 4.48 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 9]
A capacitor element was manufactured in the same manner as in Example 7 except that WS-300 was added in an amount of 3.58 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 10]
Example 1 except that the molecular weight of polyacrylic acid was 25,000 (the number of moles of carboxyl groups per gram was 13.8 mmol / g) and the amount of WS-700 added was 7.67 parts by mass. A capacitor element was manufactured in the same manner. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 11]
A capacitor element was manufactured in the same manner as in Example 10 except that WS-500 was added in an amount of 7.67 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 12]
A capacitor element was manufactured in the same manner as in Example 10 except that WS-300 was added in an amount of 3.58 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 13]
A capacitor element was manufactured in the same manner as in Example 10 except that the molecular weight of polyacrylic acid was 50,000 (the number of moles of carboxyl groups per gram was 13.8 mmol / g). Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 14]
A capacitor element was manufactured in the same manner as in Example 11 except that the molecular weight of polyacrylic acid was 50,000. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 15]
A capacitor element was manufactured in the same manner as in Example 12 except that the molecular weight of polyacrylic acid was 50,000. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 16]
(Preparation of electrolyte)
In the same manner as in Example 1, an electrolytic solution was prepared.

(Pregel electrolyte preparation)
In the same manner as in Example 2, a pregel electrolyte was prepared.

(Manufacture and evaluation of capacitor elements)
A sintered body of fine tantalum powder as an anode body was electrolytically oxidized at 10 V in an aqueous phosphoric acid solution to obtain a pellet in which the entire surface of the sintered body of fine tantalum powder was coated with a dielectric layer. Next, the pellet covered with this dielectric layer was immersed in a 30% by mass p-toluenesulfonic acid ferric methanol solution that is an oxidizing agent and a dopant for 10 minutes and dried at room temperature for 30 minutes. Next, it was immersed in 3,4-ethylenedioxythiophene, which is a monomer that gives a conductive polymer, for 10 minutes and kept at room temperature for 30 minutes to polymerize 3,4-ethylenedioxythiophene. Then, it was immersed in ethanol and the unreacted substance and the oxidizing agent residue were washed. The filling of these oxidizing agents and a series of polymerization operations for filling and washing 3,4-ethylenedioxythiophene were repeated five times to form a conductive polymer layer composed of a conductive polyethylenedioxythiophene layer.

  Subsequently, the conductive polymer layer was impregnated with the pregel electrolyte prepared above for 10 minutes, and was impregnated with the pregel electrolyte until reaching the vicinity of the dielectric layer. Then, the gel electrolyte layer was formed by heating at 125 ° C. for 20 minutes. Furthermore, a solid electrolytic capacitor element was manufactured by sequentially forming a graphite layer and a silver layer and molding with a packaging resin. About the obtained solid electrolytic capacitor, evaluation similar to Example 1 was implemented. The results are shown in Table 1.

[Example 17]
A solid electrolytic capacitor element was prepared in the same manner as in Example 16 except that the addition amount of polyacrylic acid (molecular weight: 5,000) was 10 parts by mass, and WS-700 was added in an amount of 15.33 parts by mass in terms of solid content. Manufactured. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 18]
A solid electrolytic capacitor element was prepared in the same manner as in Example 16 except that the addition amount of polyacrylic acid (molecular weight 5,000) was 14 parts by mass and WS-700 was added 21.47 parts by mass in terms of solid content. Manufactured. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.
The

[Example 19]
A solid electrolytic capacitor element was produced in the same manner as in Example 16 except that WS-500 was added as compound B in an amount of 7.67 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 20]
A solid electrolytic capacitor element was produced in the same manner as in Example 16 except that WS-300 was added as compound B in an amount of 4.47 parts by mass in terms of solid content. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 21]
A solid electrolytic capacitor element was produced in the same manner as in Example 16 except that the molecular weight of polyacrylic acid was 25,000. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 22]
A solid electrolytic capacitor element was produced in the same manner as in Example 16 except that the molecular weight of polyacrylic acid was 50,000. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Example 23]
Except that the molecular weight of polyacrylic acid was 100,000 (the number of moles of carboxyl groups per gram is 13.8 mmol / g), and WS-700 was added in an amount of 10.22 parts by mass in terms of solid content. In the same manner as in Example 16, a solid electrolytic capacitor element was produced. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Comparative Example 1]
A capacitor element was manufactured in the same manner as in Example 1 except that the winding element was impregnated with only the electrolytic solution prepared in Example 1 without adding a gelling agent. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Comparative Example 2]
A solid electrolytic capacitor element was prepared in the same manner as in Example 16 except that a solid electrolytic capacitor was produced by impregnating the conductive polymer layer only with the electrolytic solution prepared in Example 1 without adding a gelling agent. Manufactured. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Comparative Example 3]
A copolymer of N, N-dimethylacrylamide and acrylic acid containing a nitrogen atom in the main chain skeleton with respect to 100 parts by mass of the electrolytic solution prepared in Example 1 (the number of moles of carboxyl groups per gram is 13. 8 mmol / g) A capacitor element was produced in the same manner as in Example 1 except that 5 parts by mass and 10 parts by mass of WS-700 were added in terms of solid content to prepare a pregel electrolyte. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

[Comparative Example 4]
5 parts by weight of a copolymer of N, N-dimethylacrylamide and acrylic acid and 10 parts by weight of WS-700 in terms of solid content are added to 100 parts by weight of the electrolytic solution prepared in Example 1, and pregel electrolysis A solid electrolytic capacitor element was produced in the same manner as in Example 16 except that the liquid was prepared. Moreover, the same evaluation as Example 1 was implemented. The results are shown in Table 1.

  As shown in Table 1, it was found that the electrolytic capacitor using the gel electrolyte composition of the present invention was excellent in heat resistance because the decrease in capacity was suppressed even at high temperatures. On the other hand, as a capacitor of Comparative Example 1 and Comparative Example 2 prepared without using the gelling agent of the present invention and Compound A, N, N-dimethylacrylamide and acrylic acid containing nitrogen atoms in the main chain skeleton were used. The capacitors of Comparative Example 3 and Comparative Example 4 produced using the copolymer were inferior in heat resistance as compared with the capacitor of the present invention.

1: Anode body 2: Dielectric layer 3: Cathode body 4: Gel electrolyte 5: Separator 6: Conductive polymer layer 6A: First conductive polymer layer 6B: Second conductive polymer layer 7: Graphite Layer 8: Silver layer

Claims (6)

A composition for a gel electrolyte comprising an electrolytic solution and a gelling agent, wherein the gelling agent does not contain a nitrogen atom in the main chain skeleton and has a carboxyl group, and a compound B having an oxazoline group When, only contains, the content ratio of the compound B and the compound a, the number of moles of the carboxyl group contained in the said compound a, a value obtained by dividing the number of moles of oxazoline group contained in the said compound B is 1.5 or more 2 The composition for gel electrolytes characterized by being 5 or less .   The composition for gel electrolyte according to claim 1, wherein the compound A has a molecular weight of 50,000 or less. The composition for gel electrolyte according to claim 1 or 2 , wherein the compound A is polyacrylic acid. The gel electrolyte formed by gelatinizing the composition for gel electrolytes as described in any one of Claims 1-3 . A composition for a gel electrolyte comprising an electrolytic solution and a gelling agent, wherein the gelling agent does not contain a nitrogen atom in the main chain skeleton and has a carboxyl group, and a compound B having an oxazoline group And an electrolytic capacitor comprising an electrolyte layer containing a gel electrolyte formed by gelling a composition for gel electrolyte. The electrolytic capacitor according to claim 5 , further comprising a conductive polymer in the electrolyte layer.

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