JP2021106261A - Electrolytic capacitor electrolytic solution and electrolytic capacitor - Google Patents

Abstract

To provide an electrolytic capacitor having excellent withstand voltage at high temperatures without reducing electric conductivity of electrolytic solution.SOLUTION: Electrolytic capacitor electrolytic solution includes a polymer (A) including a (meth)acrylic monomer (a) as an essential constituent monomer, a solvent (C), and an electrolyte (D), where a content of a (meth)acrylic monomer (a1) represented by the general formula (1) is 30 to 100 wt.% based on the total monomers constituting the polymer (A). CH2=CR1-CO-X-R2 (1) [in the general formula (1), R1 represents a hydrogen atom or a methyl group, R2 represents a hydrocarbon group, and X represents a residue obtained by removing a hydrogen atom from a hydroxy group of a diol]SELECTED DRAWING: None

Description

The present invention relates to an electrolytic solution for an electrolytic capacitor and an electrolytic capacitor containing the electrolytic solution.

Electrolytic capacitors are widely used in various electrical and electronic products, and their applications are wide-ranging, such as charge storage, noise removal, and phase adjustment. In recent years, in order to enable an electrolytic capacitor to operate even at a higher drive voltage, there is an increasing need for improving the withstand voltage, and various improvements have been attempted. Especially for applications where the temperature tends to be high during driving, improvement of the withstand voltage at high temperature is required.

For example, Patent Document 1 discloses a technique for improving the withstand voltage by containing a polyethylene glycol-polyacrylic acid graft copolymer or a polypropylene glycol-polyacrylic acid graft copolymer in an electrolytic solution for an electrolytic capacitor. ing.

Further, Patent Document 2 discloses that the withstand voltage of a capacitor is improved by using an electrolytic solution containing a polymer containing a (meth) acrylic monomer having a hydroxy group as a constituent component. However, although the withstand voltage of the electrolytic capacitors described in Patent Documents 1 and 2 is improved, there is a problem that the viscosity of the electrolytic solution is high and the conductivity is lowered.

JP-A-2002-217067 International Publication No. 2017/023800

An object of the present invention is to provide an electrolytic capacitor having an excellent withstand voltage at a high temperature without lowering the conductivity of the electrolytic solution.

The present inventors have arrived at the present invention as a result of diligent studies to solve the above problems.
That is, the present invention is an electrolytic solution for an electrolytic capacitor containing a polymer (A), a solvent (C) and an electrolyte (D) containing the (meth) acrylic monomer (a) as an essential constituent monomer, as described below. Electrolyte characterized in that the content of the (meth) acrylic monomer (a1) represented by the general formula (1) is 30 to 100% by weight based on all the monomers constituting the polymer (A). An electrolytic solution for a capacitor; and an electrolytic capacitor containing the electrolytic solution for the electrolytic capacitor.
CH ₂ = CR ^1- CO-X-R ² (1)
[In the general formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an aliphatic hydrocarbon group, and X is a residue obtained by removing a hydrogen atom from the hydroxyl group of the diol. ]

By using the electrolytic solution for an electrolytic capacitor of the present invention, it is possible to provide an electrolytic capacitor having an excellent withstand voltage at a high temperature without causing a decrease in conductivity.

The electrolytic solution for an electrolytic capacitor of the present invention contains a polymer (A), a solvent (C) and an electrolyte (D) containing the (meth) acrylic monomer (a) as an essential constituent monomer as essential components.

In the polymer (A) of the present invention, the content of the (meth) acrylic monomer (a1) represented by the general formula (1) is based on the total weight of all the monomers constituting the polymer (A). , 30-100% by weight. When the content of the (meth) acrylic monomer (a1) represented by the general formula (1) is less than 30% by weight with respect to the total weight of all the monomers constituting the polymer (A), the withstand voltage Get worse.
Further, the content of the (meth) acrylic monomer (a1) represented by the general formula (1) is based on the total weight of all the monomers constituting the polymer (A) from the viewpoint of withstand voltage. It is preferably 50 to 100% by weight, more preferably 70 to 100% by weight.

In the present invention, "(meth) acryloyl" means both or either of "acryloyl" and "methacrylic acid", and "(meth) acrylate" means both or either of "acrylate" and "methacrylate". "(Meta) acrylic" means both "acrylic" and "methacrylic", or "(meth) acryloyloxy" means both "acryloyloxy" and "methacrylicoxy" or Means either.

The (meth) acrylic monomer (a) in the present invention includes a (meth) acrylic monomer (a1) represented by the following general formula (1), a (meth) acrylic monomer (a2) having a carboxy group, and other (meth) acrylic monomers. ) Acrylic monomer (a3) and the like can be mentioned.
CH ₂ = CR ^1- CO-X-R ² (1)
[In the general formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an aliphatic hydrocarbon group, and X is a residue obtained by removing a hydrogen atom from the hydroxyl group of the diol. ]

In the general formula (1), R ¹ is a hydrogen atom or a methyl group, and is preferably a methyl group from the viewpoint of thermal stability of the polymer at high temperature.
R ² is an aliphatic hydrocarbon group.
Aliphatic hydrocarbon groups include saturated chain aliphatic hydrocarbon groups having 1 to 8 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, etc.) and saturated alicyclic hydrocarbons having 4 to 6 carbon atoms. Examples thereof include a hydrogen group (for example, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc.).
Of these groups, a saturated chain aliphatic hydrocarbon group having 1 to 8 carbon atoms is preferable from the viewpoint of solubility.

X is a residue obtained by removing a hydrogen atom from the hydroxyl group of the diol.
Examples of the diol include alkylene glycols having 2-36 carbon atoms (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, octanediol, and decanediol. , Dodecanediol, tetradecanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, etc.); alkylene ether glycol having 4 to 36 carbon atoms (diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene) Glycol, polytetramethylene ether glycol, etc.); Alicyclic diol having 4 to 36 carbon atoms (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); (Abbreviated as) [EO, propylene oxide (hereinafter abbreviated as PO), butylene oxide (hereinafter abbreviated as BO), etc.] Additives (additional moles 1-120); bisphenol compounds (bisphenol A, bisphenol F, bisphenol S) AO (EO, PO, BO, etc.) adduct (2 to 30 moles added); polylactone diol (poly ε-caprolactone diol, etc.); castor oil-based polyol; polybutadiene diol, etc.
Among these diols, from the viewpoint of reducing the viscosity of the electrolytic solution, polyalkylene ether glycol is preferable, polyalkylene ether glycol having 4 to 36 carbon atoms is more preferable, and polyethylene having 4 to 36 carbon atoms is particularly preferable. Glycol and polypropylene glycol having 6 to 36 carbon atoms, most preferably polyethylene glycol having 4 to 20 carbon atoms and polypropylene glycol having 6 to 20 carbon atoms.

Specific examples of the (meth) acrylic monomer (a1) represented by the general formula (1) in the present invention include methoxydipropylene glycol (meth) acrylate and methoxypolyethylene glycol (meth) acrylate.
Of these (a1), methoxydipropylene glycol (meth) acrylate and methoxypolyethylene glycol (meth) acrylate are preferable.

As the (meth) acrylic monomer (a) constituting the polymer (A) in the present invention, in addition to the (meth) acrylic monomer (a1), a (meth) acrylic monomer (a2) having a carboxy group is a constituent monomer. May be used as.
Examples of the (meth) acrylic monomer (a2) having a carboxy group include an acid anhydride adduct (a21) having 4 to 10 carbon atoms and (meth) acrylic acid (a22) to a (meth) acrylic monomer having a hydroxy group. Can be mentioned.
Examples of the (meth) acrylic monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, hydroxyethyl (meth) acrylate, and 2- (2-hydroxyethoxy) (meth) acrylate. ) Ethyl and glycerin mono (meth) acrylate and the like.
In (a21), examples of the acid anhydride having 4 to 10 carbon atoms include succinic anhydride, maleic anhydride, phthalic anhydride, hexahydrophthalic anhydride and the like.

Specific examples of the acid anhydride additive (a21) having 4 to 10 carbon atoms to a (meth) acrylic monomer having a hydroxy group include succinic acid 2- (succinic acid 2- (succinic acid anhydride) such as 2-hydroxyethyl methacrylate. Examples thereof include meta) acryloyloxyethyl, 2- (meth) acryloyloxyethyl maleate, 2- (meth) acryloyloxyethyl phthalate and 2- (meth) acryloyloxyethyl hexahydrophthalate.
Of these (a2), (meth) acrylic acid and 2- (meth) acryloyloxyethyl succinate are preferable from the viewpoint of withstand voltage.
When the (meth) acrylic monomer (a2) having the carboxy group is used, the content of the (meth) acrylic monomer (a2) having the carboxy group is the polymer (A) from the viewpoint of withstand voltage. It is preferably 0.001 to 70% by weight, more preferably 0.01 to 30% by weight, based on the total weight of all the constituent monomers.

Other (meth) acrylic monomers other than the above-mentioned monomer (a1) represented by the general formula (1) and the (meth) acrylic monomer (a2) having a carboxy group, which constitute the polymer (A) in the present invention. Examples of a3) include alkyl (meth) acrylates having 4 to 20 carbon atoms [methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and (meth). Lauryl acrylate, etc.];
(Meta) acrylamide with 3 to 20 carbon atoms [(meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropylacrylamide and N, N-dibenzyl (meth) acrylamide, etc.];
(Meta) acrylate having a hydroxy group [polyethylene glycol mono (meth) acrylate, hydroxyethyl (meth) acrylate, 2- (2-hydroxyethoxy) ethyl (meth) acrylate, glycerin mono (meth) acrylate, etc.];
Examples thereof include (meth) acrylate having an acidic functional group (phospho group, sulfo group, etc.) other than the carboxy group [2-((meth) acryloyloxy) ethyl phosphate, 2-sulfoethyl (meth) acrylate, etc.] and the like.
Among the other (meth) acrylic monomers (a3), (meth) acrylate having a hydroxy group is preferable, and hydroxyethyl (meth) acrylate and 2- (2- (2-) (meth) acrylate are particularly preferable. Hydroxyethoxy) ethyl.
These monomers may be used alone or in combination of two or more.
When the other (meth) acrylic monomer (a3) is used, the content of the other (meth) acrylic monomer (a3) is the total unit constituting the polymer (A) from the viewpoint of withstand voltage. It is preferably 0.001 to 50% by weight, more preferably 0.01 to 30% by weight, based on the total weight of the polymers.

The polymer (A) in the present invention may contain a monomer other than the (meth) acrylic monomer (a) as a constituent monomer. Examples of the monomer other than (a) include compounds having a polymerizable double bond other than (a) (vinyl compounds such as olefins and styrene compounds).

The number average molecular weight (hereinafter abbreviated as Mn) of the polymer (A) is preferably 1,000 or more, more preferably 3,000 or more, and particularly preferably 5,000 or more.
The Mn of the polymer (A) is preferably 100,000 or less, more preferably 80,000 or less, and particularly preferably 50,000 or less.
When Mn is 1,000 or more, it is preferable from the viewpoint of withstand voltage of the electrolytic solution, and when it is 100,000 or less, it is preferable from the viewpoint of impregnation property of the electrolytic solution into the element.
The Mn in the present invention is a value measured by the gel permeation chromatography (GPC) method described in Examples.

The polymer (A) can be synthesized by polymerizing the (meth) acrylic monomer (a) using a known method (method described in JP-A-5-117330 and the like). For example, a monomer such as the monomer (a) is synthesized by a solution polymerization method in which a monomer such as the monomer (a) is reacted with a radical initiator (azobisisobutyronitrile or the like) in a solvent (toluene or the like), and then the solvent used for the polymerization is reduced in pressure. It can be obtained by distilling off by drying.
The above-mentioned other additives may be mixed with the solvent used for synthesis, or may be mixed with the polymer (A) after distilling off the solvent.

The solvent (C) in the present invention includes an alcohol solvent [monool (methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, etc.), diol (ethylene glycol, ethylene glycol monobutyl ether, propylene glycol, diethylene glycol, polyethylene glycol (Mn:)). 600 or less) etc.), etc.], amide solvent (N-methylformamide, N-ethylformamide and N, N-dimethylformamide, etc.), lactone solvent (α-acetyl-γ-butyrolactone, β-butyrolactone, γ-butyrolactone, γ -Valerolactone and δ-Valerolactone, etc.), nitrile solvents (acetritale, propionitrile, butyronitrile, acrylonitrile, methacrylic nitrile, benzonitrile, etc.), sulfoxide solvents (dimethyl sulfoxide, methyl ethyl sulfoxide and diethyl sulfoxide) and sulfon solvents (sulfolane) And ethyl methyl sulfone, etc.) and the like.
Among these solvents, from the viewpoint of the solubility of the electrolyte and the dielectric constant of the solvent, an alcohol solvent is preferable, a diol is more preferable, ethylene glycol and propylene glycol are particularly preferable, and ethylene glycol is most preferable. ..
One of these solvents (C) may be used alone, or two or more of them may be used in combination.

The solvent (C) preferably contains ethylene glycol as an essential component. When the solvent (C) contains a solvent other than ethylene glycol, the weight ratio of ethylene glycol to the total weight of the solvent (C) is preferably 10 to 100% by weight, more preferably 30 to 100% by weight. %.

As the electrolyte (D) contained in the electrolytic solution for electrolytic capacitors of the present invention, a known electrolyte used for the electrolytic solution for electrolytic capacitors can be used, but carboxylate anion and ammonium, primary ammonium, and second are preferable. It is an electrolyte composed of cations selected from the group consisting of tertiary ammonium, tertiary ammonium and amidinium. The above-mentioned electrolyte (D) may be used alone or in combination of two or more.

The carboxylate anion is an anion obtained by removing a hydrogen ion from the carboxy group of a carboxylic acid, preferably having a chemical formula amount of 500 or less, and a saturated polycarboxylic acid (succinic acid, malonic acid, succinic acid, glutaric acid). , Adipic acid, Pimelli acid, Sveric acid, Azelaic acid, 2-Methylaseline acid, Sevacinic acid, 1,5-octanedicarboxylic acid, 4,5-octanedicarboxylic acid, 1,9-nonandicarboxylic acid, 1,10- Decandycarboxylic acid, 1,6-decandicarboxylic acid, 5,6-decandicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecane Dicarboxylic acid, 1,15-pentadecanedicarboxylic acid, methylmalonic acid, ethylmalonic acid, propylmalonic acid, butylmalonic acid, pentylmalonic acid, hexylmalonic acid, dimethylmalonic acid, diethylmalonic acid, methylpropylmalonic acid, methylbutyl Maronic acid, ethylpropylmalonic acid, dipropylmalonic acid, methylsuccinic acid, ethylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-methyl -3-ethylglutaric acid, 3,3-diethylglutaric acid, 3,3-dimethylglutaric acid, 3-methyladipic acid, etc.);
Saturated monocarboxylic acids (girate, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid and undecanoic acid, etc.)
Unsaturated monocarboxylic acid [(meth) acrylic acid, crotonic acid, oleic acid, etc.];
Unsaturated aliphatic polycarboxylic acids (maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.);
Aromatic monocarboxylic acids (benzoic acid, silicic acid, naphthoic acid, toluic acid, ethyl benzoic acid, propyl benzoic acid, isopropyl benzoic acid, butyl benzoic acid, isobutyl benzoic acid, secondary butyl benzoic acid, tertiary butyl benzoic acid , Hydroxybenzoic acid, ethoxybenzoic acid, propoxybenzoic acid, isopropoxybenzoic acid, butoxybenzoic acid, isobutoxybenzoic acid, second butoxybenzoic acid, third butoxybenzoic acid, aminobenzoic acid, N-methylaminobenzoic acid, N -Ethylaminobenzoic acid, N-propylaminobenzoic acid, N-isopropylaminobenzoic acid, N-butylaminobenzoic acid, N-isobutylaminobenzoic acid, N-2nd butylaminobenzoic acid, N-3th butylaminobenzoic acid Acids, N, N-dimethylaminobenzoic acid and N, N-diethylaminobenzoic acid, etc.);
And anions obtained by removing hydrogen ions from the carboxy group of a carboxylic acid such as an aromatic polycarboxylic acid (phthalic acid, isophthalic acid, terephthalic acid, etc.).
Of these, from the viewpoint of withstand voltage, preferred are anions obtained by removing hydrogen ions from the carboxy groups of saturated polycarboxylic acids and unsaturated polycarboxylic acids.

Examples of the cation include ammonium, primary ammonium, secondary ammonium, tertiary ammonium and amidinium.
Examples of ammonium include unsubstituted ammonium.
Examples of the primary ammonium include ammonium having 1 to 3 carbon atoms (methylammonium, ethylammonium, propylammonium, isopropylammonium, etc.).
Examples of the secondary ammonium include ammonium having 2 to 6 carbon atoms (dimethylammonium, diethylammonium, methylethylammonium, methylpropylammonium, methylisopropylammonium, etc.).
Examples of the tertiary ammonium include ammonium having 3 to 9 carbon atoms (trimethylammonium, triethylammonium, dimethylethylammonium, dimethylpropylammonium, dimethylisopropylammonium, etc.).
Examples of the quaternary ammonium include ammonium having 4 to 12 carbon atoms (tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium, triethylmethylammonium, tetraethylammonium, etc.).

The amidinium can be used without particular limitation as long as it is an amidinium that forms a salt with the carboxylate anion.
Examples of amidinium include imidazolinium and cations in which the hydrogen atom of imidazolinium is substituted with an alkyl group (1,2,3,4-tetramethylimidazolinium, 1,3,4-trimethyl-2-ethylimidazoli). Nium, 1,3-dimethyl-2,4-diethylimidazolinium and 1,2-dimethyl-3,4-diethylimidazolinium, etc.), imidazolium, and cations in which the hydrogen atom of imidazolium is substituted with an alkyl group. (1,3-Dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,3-trimethylimidazolium, etc.) and the like.

Among ammonium, primary ammonium, secondary ammonium, tertiary ammonium and amidinium, ammonium, primary ammonium, secondary ammonium and tertiary ammonium are preferable from the viewpoint of withstand voltage, and more preferable. Are unsubstituted ammonium, primary ammonium and tertiary ammonium.

The electrolytic solution for an electrolytic capacitor of the present invention may contain a boric acid compound (E), if necessary.
Examples of the boric acid compound (E) include boric acid and boric acid esters.
Examples of the borate ester include alkyl borate (alkyl borate having 1 to 6 carbon atoms such as triethyl borate) and aryl borate (triphenyl borate and the like).
Of these, boric acid is preferable from the viewpoint of withstand voltage.

The electrolytic solution for an electrolytic capacitor of the present invention may further contain other additives, if necessary.
Specific examples of other additives include gas generation inhibitors (nitro compounds such as o-nitrobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, o-nitrophenol and p-nitrophenol) and withstand voltage. Examples thereof include improvers (polyethylene glycol (Mn: 600 or more), polypropylene glycol, polyvinyl alcohol, mannitol, etc.).
Of these, a withstand voltage improver is preferably used for the purpose of improving the withstand voltage, and it is more preferable to use mannitol.

In the electrolytic solution for an electrolytic capacitor of the present invention, the weight ratio of the polymer (A) to the total weight of the electrolytic solution for an electrolytic capacitor is preferably 0.5 to 40% by weight, more preferably 1 to 30% by weight. It is particularly preferably 5 to 20% by weight.
When the polymer (A) containing 0.5% by weight or more is contained, the withstand voltage is good, and when it is 40% by weight or less, the conductivity is good.
The weight ratio of the solvent (C) to the total weight of the electrolytic solution for the electrolytic capacitor is preferably 50 to 99% by weight, more preferably 60 to 80% by weight, from the viewpoint of conductivity.
The weight ratio of the electrolyte (D) to the total weight of the electrolytic solution for the electrolytic capacitor is preferably 0.5 to 40% by weight, more preferably 5 to 30% by weight from the viewpoint of conductivity.

The weight ratio of the boric acid compound (E) to the total weight of the electrolytic solution for the electrolytic capacitor is preferably 0 to 10% by weight, more preferably 0.5 to 5% by weight, from the viewpoint of withstand voltage.
The total weight ratio of the other additives to the total weight of the electrolytic solution for the electrolytic capacitor is preferably 0 to 10% by weight, more preferably 0 to 5% by weight.

The method for producing the electrolytic solution for an electrolytic capacitor of the present invention is not particularly limited. For example, a known mechanical mixing method (for example, a polymer (A), a solvent (C) and an electrolyte (D) and, if necessary, a boric acid compound (E) and other additives in a temperature range of 20 to 100 ° C. For example, it can be produced by uniformly mixing by using a mechanical stirrer or a method using a magnetic stirrer).

The electrolytic capacitor of the present invention, such as an aluminum electrolytic capacitor, may include the above-mentioned electrolytic solution for the electrolytic capacitor of the present invention, and the shape, size, and the like are not limited. The electrolytic capacitor of the present invention is, for example, a roll-up type electrolytic capacitor in which a separator is interposed between an anode (aluminum oxide foil) in which aluminum oxide is formed on the surface of the anode and a cathode aluminum foil. Examples include capacitors constructed by turning.

The electrolytic capacitor of the present invention such as an aluminum electrolytic capacitor is, for example, impregnated with a separator (kraft paper, Manila paper, etc.) using the electrolytic solution for the electrolytic capacitor of the present invention as a driving electrolytic solution, and together with a positive cathode, has a bottomed tubular shape. After storing in an aluminum case, it can be obtained by sealing the opening of the aluminum case with a sealing rubber (butyl rubber, silicone rubber, etc.).

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

The Mn of the polymer (A) synthesized in the production example and the comparative production example was measured using GPC under the following conditions.
Equipment (example): HLC-8120 manufactured by Toso Co., Ltd.
Column (example): 2 TSK GEL GMH6 [manufactured by Toso Co., Ltd.]
Measurement temperature: 40 ° C
Sample solution: 0.25 wt% THF solution Solution injection amount: 100 μl
Detection device: Refractive index detector Reference material: Tosoh standard polystyrene (TSK standard POLYSTYRENE) 12 points (weight average molecular weight: 500 1050 2800 5970 9100 18100 37900 96400 190000 355000 1090000 2890000)

<Production Example 1: Synthesis of polymer (A-1)>
Methyl isobutyl ketone [manufactured by Wako Pure Chemical Industries, Ltd.] 200 parts by weight and methoxypolyethylene glycol acrylate (I) [light acrylate 130A, manufactured by Kyoeisha Chemical Co., Ltd.] in a flask equipped with a stirrer, a thermometer and a cooling tube. 100 parts by weight was added and heated to 80 ° C. A solution prepared by dissolving 1 part by weight of azobisisobutyronitrile [manufactured by Wako Pure Chemical Industries, Ltd.] prepared in advance in 5 parts by weight of methyl isobutyl ketone was added dropwise thereto over 3 hours. After completion of the dropping, the mixture was further heated for 3 hours. Then, methyl isobutyl ketone was distilled off by drying under reduced pressure at 100 ° C. and 0.5 kPa to synthesize a polymer (A-1).

<Production Example 2: Synthesis of polymer (A-2)>
In Production Example 1, the polymer (A-2) was synthesized in the same manner as in Production Example 1 except that the input amount of methyl isobutyl ketone was changed from 200 parts by weight to 120 parts by weight.

<Production Example 3: Synthesis of polymer (A-3)>
Same as Production Example 1 except that 100 parts by weight of methoxypolyethylene glycol methacrylate (I) [M-90G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.] was used instead of methoxypolyethylene glycol acrylate (I). The polymer (A-3) was synthesized.

<Production Example 4: Synthesis of polymer (A-4)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), methoxypolyethylene glycol methacrylate (I) [M-90G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.] 80 parts by weight, methacrylic acid [Wako Pure Chemical Industries, Ltd. )] 10 parts by weight and 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] 10 parts by weight were used in the same manner as in Production Example 1 to synthesize the polymer (A-4).

<Production Example 5: Synthesis of polymer (A-5)>
In Production Example 1, instead of methoxypolypropylene glycol acrylate (I), methoxydipropylene glycol acrylate [light acrylate DPM-A, manufactured by Kyoeisha Chemical Co., Ltd.] 80 parts by weight, methacrylic acid [manufactured by Wako Pure Chemical Industries, Ltd.] ] 10 parts by weight and 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] The polymer (A-5) was synthesized in the same manner as in Production Example 1 except that 10 parts by weight was used.

<Production Example 6: Synthesis of polymer (A-6)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), 80 parts by weight of methoxypolyethylene glycol methacrylate (I) [M-90G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.], anhydrous shavings of 2-hydroxyethyl methacrylate The polymer (A-6) was synthesized in the same manner as in Production Example 1 except that 20 parts by weight of an acid adduct [light ester HO-MS (N), manufactured by Kyoeisha Chemical Co., Ltd.] was used.

<Production Example 7: Synthesis of polymer (A-7)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), 70 parts by weight of methoxypolyethylene glycol methacrylate (II) [M-40G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.], methacrylic acid [Wako Pure Chemical Industry Co., Ltd. )] 5 parts by weight and 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] 25 parts by weight were used in the same manner as in Production Example 1 to synthesize a polymer (A-7).

<Production Example 8: Synthesis of polymer (A-8)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), methoxypolyethylene glycol methacrylate (II) [M-40G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.] 80 parts by weight, methacrylic acid [Wako Pure Chemical Industry Co., Ltd. )] 5 parts by weight and 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] 15 parts by weight were used in the same manner as in Production Example 1 to synthesize the polymer (A-8).

<Production Example 9: Synthesis of polymer (A-9)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), methoxypolyethylene glycol methacrylate (II) [M-40G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.] 30 parts by weight, methacrylic acid [Wako Pure Chemical Industry Co., Ltd. )] 65 parts by weight and 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] 5 parts by weight were carried out in the same manner as in Production Example 1 to synthesize a polymer (A-9).

<Production Example 10: Synthesis of polymer (A-10)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), 70 parts by weight of methoxypolyethylene glycol methacrylate (II) [M-40G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.], methoxypolyethylene glycol methacrylate (III) [M -90G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.] 10 parts by weight, methacrylic acid [manufactured by Wako Pure Chemical Industries, Ltd.] 5 parts by weight and 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] 15 parts by weight. A polymer (A-10) was synthesized in the same manner as in Production Example 1 except that it was used.

<Production Example 11: Synthesis of polymer (A-11)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), 10 parts by weight of methoxypolyethylene glycol methacrylate (II) [M-40G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.], methoxypolyethylene glycol methacrylate (III) [M -90G, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.] 60 parts by weight, methacrylic acid [manufactured by Wako Pure Chemical Industries, Ltd.] 5 parts by weight and 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] 25 parts by weight. A polymer (A-11) was synthesized in the same manner as in Production Example 1 except that it was used.

<Production Example 12: Synthesis of polymer (A-12)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), methoxypolyethylene glycol acrylate (II) [Blemmer PE-200, manufactured by Nichiyu Co., Ltd.] 80 parts by weight, acrylic acid [Wako Pure Chemical Industries, Ltd. The polymer (A-12) was synthesized in the same manner as in Production Example 1 except that 5 parts by weight and 15 parts by weight of 2-hydroxyethyl acrylate [manufactured by Nippon Shokubai Co., Ltd.] were used.

<Production Example 13: Synthesis of polymer (A-13)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), 60 parts by weight of methoxypolyethylene glycol acrylate (II) [Blemmer PME-200, manufactured by Nichiyu Co., Ltd.], acrylic acid [Wako Pure Chemical Industries, Ltd. The polymer (A-13) was synthesized in the same manner as in Production Example 1 except that 5 parts by weight and 35 parts by weight of 2-hydroxyethyl acrylate [manufactured by Nippon Shokubai Co., Ltd.] were used.

<Production Example 14: Synthesis of polymer (A-14)>
In Production Example 1, the polymer (A-14) was synthesized in the same manner as in Production Example 1 except that the input amount of azobisisobutyronitrile was changed from 1 part by weight to 2 parts by weight.

<Production Example 15: Synthesis of polymer (A-15)>
In Production Example 1, the polymer (A-14) was synthesized in the same manner as in Production Example 1 except that the input amount of azobisisobutyronitrile was changed from 1 part by weight to 0.1 parts by weight.

<Production Example 16: Synthesis of polymer (A-16)>
In Production Example 1, the same as in Production Example 1 except that 100 parts by weight of 2-ethylhexyloxypolyethylene glycol acrylate [Aronix M-120, manufactured by Toa Synthetic Co., Ltd.] was used instead of methoxypolyethylene glycol acrylate (I). The polymer (A-16) was synthesized.

<Comparative Production Example 1: Synthesis of Polymer (A'-1)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), 40 parts by weight of methacrylic acid [manufactured by Wako Pure Chemical Industries, Ltd.] and 60 parts by weight of 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] were used. A polymer (A'-1) for comparison was synthesized in the same manner as in Production Example 1 except that it was used.

<Comparative Production Example 2: Synthesis of Polymer (A'-2)>
Production Example 1 except that 20 parts by weight of methoxypolyethylene glycol acrylate (I) and 80 parts by weight of methacrylic acid [manufactured by Wako Pure Chemical Industries, Ltd.] were used instead of methoxypolyethylene glycol acrylate (I). A polymer (A'-2) for comparison was synthesized in the same manner as above.

<Comparative Production Example 3: Synthesis of Polymer (A'-3)>
In Production Example 1, instead of methoxypolyethylene glycol acrylate (I), 80 parts by weight of polyethylene glycol methacrylate [Blemmer PE-200, manufactured by Kyoeisha Chemical Co., Ltd.] and 5 weights of methacrylic acid [manufactured by Wako Pure Chemical Industries, Ltd.] A polymer (A'-3) for comparison was synthesized in the same manner as in Production Example 1 except that 15 parts by weight of 2-hydroxyethyl methacrylate [manufactured by Nippon Catalyst Co., Ltd.] was used.

Table 1 shows the number average molecular weights of the polymers (A-1) to (A-16) and the comparative polymers (A'-1) to (A'-3).

<Manufacturing example 17>
80 parts by weight of methanol and 20 parts by weight of 1,6-decandicarboxylic acid were put into a container, and 2.5 parts by weight of ammonia gas was blown into the container to neutralize the mixture. Then, methanol was removed under reduced pressure (0.5 kPa) at 80 ° C. to obtain 22.2 parts by weight of a 1,6-decandicarboxylic acid diammonium salt as the electrolyte (D).

<Preparation of electrolytic solution (D)>
<Examples 1 to 18, Comparative Examples 1 to 4>
The polymers (A-1) to (A-16) as the polymer (A) or the comparative polymers (A'-1) to (A'-3) synthesized in the comparative production example, and the electrolyte (D). ), Ethylene glycol or propylene glycol as the solvent (C), and boric acid as the boric acid compound (E), if necessary, by weight shown in Table 2. The electrolytes of Examples 1 to 18 and the electrolytes of Comparative Examples 1 to 4 were prepared by blending in parts. In addition, the evaluation was performed by the following method. The results are shown in Table 2.

<Conductivity>
The conductivity of the electrolytic solutions of Examples and Comparative Examples at 30 ° C. was measured using an electric conductivity meter CM-40S [manufactured by Toa Denpa Kogyo Co., Ltd.].

<Spark voltage (25 ° C, 85 ° C)>
A high-pressure chemical etching aluminum foil as an anode and a plain aluminum foil as a cathode are used, and the contact area between the electrolytic solutions for electrolytic capacitors (Examples 1 to 18 and Comparative Examples 1 to 4) is 10 cm ² . Impregnated as. Next, the temperature of the electrolytic solution for the electrolytic capacitor was adjusted to 25 ° C. and 85 ° C., and a load by the constant current method (2 mA) was used using a constant voltage / constant current DC power supply device [manufactured by Takasago Seisakusho Co., Ltd., GP0650-05R]. And measured the voltage. Time was plotted on the horizontal axis and voltage was plotted on the vertical axis, and the rising curve of the voltage was observed with the passage of time, and the voltage at the time when the rising curve was first disturbed by spark or scintillation was defined as the spark voltage. The higher the spark voltage, the higher the withstand voltage.

<Viscosity>
The viscosity of the electrolytic solution for an electrolytic capacitor at 25 ° C. was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.).

The electrolytic solutions of Examples 1 to 18 of the present invention have a low viscosity and exhibit excellent withstand voltage and conductivity, maintain an excellent withstand voltage even at a high temperature of 85 ° C., and have a small decrease in withstand voltage.
On the other hand, the electrolytic solution of Comparative Example 1 does not contain the polymer (A) and has a low withstand voltage. Further, the electrolytic solution of Comparative Example 2 has an improved withstand voltage as compared with the electrolytic solution of Comparative Example 1 to which no additive is added, but the conductivity is significantly reduced. It is considered that this is because a large number of carboxy groups and hydroxyl groups contained in the polymer (A'-1) form hydrogen bonds with the solvent to inhibit the movement of anions. Further, Comparative Examples 3 and 4 in which the content of the (meth) acrylic monomer (a1) represented by the general formula (1) is less than 30% by weight based on the weight of all the monomers constituting the polymer are electrolytic. Since the liquid viscosity is high, the conductivity is low.

Since the electrolytic capacitor using the electrolytic solution for the electrolytic capacitor of the present invention uses an electrolytic solution having a high withstand voltage at a high temperature while maintaining a high conductivity, it is used for electric products and electronic products that require a high driving voltage. Can be suitably used as a part.
The electrolytic solution for an electrolytic capacitor of the present invention is suitable as an electrolytic solution for an electrolytic capacitor for mobile applications such as notebook computers, which are affected by the outside temperature and tend to become hot during driving, particularly for in-vehicle applications.

Claims (7)

An electrolytic solution for an electrolytic capacitor containing a polymer (A), a solvent (C) and an electrolyte (D) containing the (meth) acrylic monomer (a) as an essential constituent monomer, wherein the (meth) acrylic monomer (meth) acrylic monomer (meth) As a), the (meth) acrylic monomer (a1) represented by the following general formula (1) is contained, and the content of the (meth) acrylic monomer (a1) constitutes all the monomers constituting the polymer (A). An electrolytic solution for an electrolytic capacitor, which is characterized in that it is 30 to 100% by weight based on the weight.
CH ₂ = CR ^1- CO-X-R ² (1)
[In the general formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an aliphatic hydrocarbon group, and X is a residue obtained by removing the hydrogen atom from the hydroxyl group of the diol. ] ^{The electrolytic solution for an electrolytic capacitor according to claim 1, wherein R 2} is a saturated chain aliphatic hydrocarbon group having 1 to 8 carbon atoms in the general formula (1). The electrolytic solution for an electrolytic capacitor according to claim 1 or 2, wherein X is a residue obtained by removing a hydrogen atom from the hydroxyl group of the polyalkylene ether glycol in the general formula (1). The electrolytic solution for an electrolytic capacitor according to any one of claims 1 to 3, wherein the polymer (A) has a number average molecular weight of 1,000 to 100,000. The electrolytic capacitor according to any one of claims 1 to 4, further comprising a (meth) acrylic monomer (a2) having a carboxy group as the (meth) acrylic monomer (a) constituting the polymer (A). Electrolyte for. The electrolytic solution for an electrolytic capacitor according to any one of claims 1 to 5, further containing a boric acid compound (E). An electrolytic capacitor containing an electrolytic solution for an electrolytic capacitor according to any one of claims 1 to 6.