Electrolytic capacitor

Abstract

The electrolytic capacitor includes a capacitor element and a liquid component. The capacitor element includes an anode body having a dielectric layer on a surface thereof, and a conductive polymer covering at least a portion of the dielectric layer. The liquid component contains an acid component and a solvent. The acid component contains a first carboxylic acid compound having a plurality of first sites. Each of the plurality of first sites independently has: a first carboxyl group including a first carbonyl group; a second carbonyl group; and a first linking group that links the first carbonyl group and the second carbonyl group.

Description

Technical Field

[0001] The present invention relates to electrolytic capacitors. Background Art

[0002] As a small, large-capacity, low-ESR (equivalent series resistance) capacitor, an electrolytic capacitor having an anode body formed with a dielectric layer, a conductive polymer covering at least a portion of the dielectric layer, and an electrolyte is considered promising. The conductive polymer includes, for example, a conjugated polymer and a dopant. As the electrolyte, a liquid component such as a non-aqueous solvent or a solution obtained by dissolving a solute in a non-aqueous solvent can be used.

[0003] Patent document 1 proposes a conductive polymer hybrid aluminum electrolytic capacitor, characterized in that it is an electrolytic capacitor having a capacitor element formed by winding an anode electrode foil and a cathode electrode foil with an aluminum dielectric oxide film formed thereon with a separator therebetween, and having a conductive polymer layer formed on the above-mentioned dielectric oxide film and an electrolyte, the above-mentioned electrolyte containing a solute and a solvent, the above-mentioned solvent containing diethylene glycol and / or triethylene glycol, and the above-mentioned solute containing a salt of a long-chain dicarboxylic acid (dicarboxylic acid) having 12 or more carbon atoms and an amine having a boiling point of 150° C. or more.

[0004] As an electrolyte solution for electrolytic capacitors, electrolyte solutions containing carboxylic acid or a salt of carboxylic acid, etc. as described in Patent Documents 2 to 4 are also known.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-64768

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 1-103821

[0009] Patent Document 3: Japanese Patent Application Publication No. 2004-71727

[0010] Patent Document 4: Japanese Patent Application Publication No. 2019-102791 Summary of the invention

[0011] Problems to be solved by the invention

[0012] As for the conductive polymer, for example, high conductivity can be obtained in a state where a dopant is doped in a conjugated polymer. In the case where the liquid component contains an acid component, it can be expected that dedoping of the dopant is suppressed and the high conductivity of the conductive polymer is maintained. However, even if a liquid component containing an acid component is used, it is actually difficult to suppress the decrease in the conductivity of the conductive polymer over time when using an electrolytic capacitor, and sometimes it is difficult to suppress the increase in ESR.

[0013] Means for solving problems

[0014] One aspect of the present invention relates to an electrolytic capacitor comprising a capacitor element and a liquid component.

[0015] The capacitor element includes an anode body having a dielectric layer on its surface and a conductive polymer covering at least a portion of the dielectric layer.

[0016] The liquid component includes an acid component and a solvent.

[0017] The acid component includes a first carboxylic acid compound having a plurality of first sites,

[0018] The plurality of first parts each independently have:

[0019] a first carboxyl group comprising a first carbonyl group;

[0020] A second carbonyl group; and

[0021] A first linking group that links the first carbonyl group and the second carbonyl group.

[0022] Effects of the Invention

[0023] In an electrolytic capacitor including a conductive polymer, a change in ESR over time can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic cross-sectional view of an electrolytic capacitor according to one embodiment of the present invention.

[0025] Figure 2 Yes Figure 1 An expanded schematic diagram of a portion of the capacitor element of an electrolytic capacitor. DETAILED DESCRIPTION

[0026] The novel features of the present invention are described in the appended claims, but both the configuration and content of the present invention, together with other objects and features of the present invention, will be better understood through the following detailed description with reference to the accompanying drawings.

[0027] In the case of using a liquid component containing an acid component in an electrolytic capacitor containing a conductive polymer, by suppressing the pH of the liquid component to a low level, dedoping in the conductive polymer is suppressed, and it is expected that the high conductivity of the conductive polymer is maintained. However, in fact, even if a liquid component containing an acid component is used, the high conductivity of the conductive polymer cannot be maintained sometimes. It is believed that this is due to the low solubility of the acid component in a non-aqueous solvent or the reaction of the acid component with the non-aqueous solvent, and the effect of suppressing the progress of dedoping cannot be fully obtained, and the conductive polymer deteriorates. If the deterioration of the conductive polymer proceeds with the use of the electrolytic capacitor, the conductivity of the conductive polymer decreases and the ESR increases.

[0028] In an electrolytic capacitor that does not contain a conductive polymer but contains a liquid component, the ESR of the electrolytic capacitor is greatly affected by the ionic conductivity of the liquid component, the state of electrical connection of the components of the electrolytic capacitor, and the like. In contrast, in an electrolytic capacitor that contains a conductive polymer and does not contain a liquid component, there is a tendency for the resistance of the conductive polymer to be higher than that of the cathode lead layer or the anode body that constitutes the cathode body. Therefore, as described above, the conductivity of the conductive polymer has a great influence on the ESR. Furthermore, as described above, the conductive polymer deteriorates during the use of the electrolytic capacitor, so in order to maintain high conductivity, it is important to stabilize the conductive polymer. In the case where the electrolytic capacitor contains a conductive polymer and a liquid component, the liquid component has a great influence on the state of the conductive polymer (also including conductivity, stability, etc.). However, for an electrolytic capacitor that does not contain a conductive polymer but contains a liquid component, there is no resistance of the conductive polymer, interaction between the conductive polymer and the liquid component, etc. Therefore, the mechanism by which the liquid component affects the ESR of the electrolytic capacitor is completely different from that of an electrolytic capacitor that contains a conductive polymer and a liquid component. Therefore, even if the liquid component of an electrolytic capacitor that does not contain a conductive polymer is applied to an electrolytic capacitor that contains a conductive polymer, it is not known whether the same effect of stabilizing the conductive polymer or suppressing the decrease in conductivity can be obtained, nor is it known whether the same effect of reducing the time-dependent change of the ESR can be obtained.

[0029] In view of the above, (1) the electrolytic capacitor of the present invention comprises a capacitor element and a liquid component,

[0030] The capacitor element includes an anode body having a dielectric layer on its surface and a conductive polymer covering at least a portion of the dielectric layer.

[0031] The liquid component includes an acid component and a solvent.

[0032] The acid component includes a first carboxylic acid compound having a plurality of first sites,

[0033] The plurality of first parts each independently have:

[0034] a first carboxyl group comprising a first carbonyl group;

[0035] A second carbonyl group; and

[0036] A first linking group that links the first carbonyl group and the second carbonyl group.

[0037] By making the liquid component contain the acid component containing the first carboxylic acid compound, the temporal change of ESR accompanying the use of the electrolytic capacitor (in other words, the temporal increase) can be reduced. The reason why the temporal change of ESR is reduced is considered to be as follows.

[0038] First, the second carbonyl group of the first carboxylic acid compound is easy to coordinate the cationic part of the conductive polymer due to the offset of the charge, so that the conductive polymer can be stabilized. In addition, since the second carbonyl group is easy to coordinate with the conductive polymer, the first carboxyl group is easy to become a state close to the conductive polymer, and therefore the conductive polymer can also be stabilized. By such a stabilizing effect of a plurality of second carbonyl groups and a plurality of first carboxyl groups, when using an electrolytic capacitor, the dedoping of the conductive polymer is suppressed, and thus the deterioration of the conductive polymer is suppressed, and high conductivity is maintained. Therefore, it can be considered that the time-dependent change of ESR is reduced.

[0039] In addition, the first carboxylic acid compound easily forms a suitable film on the surface of the dielectric layer on the surface of the anode body. Through such a film, the film repairability of the dielectric layer is improved, so even if the electrolytic capacitor is used for a long time, the leakage current can be suppressed to a low level. In addition, the time-dependent degradation of the conductive polymer is suppressed by the effect of the first carboxylic acid compound, so that a large amount of liquid components can be maintained in the conductive polymer near the dielectric layer. It can be considered that the film repairability of the dielectric layer is also improved.

[0040] In addition, the relatively high conductivity of the conductive polymer can be ensured, and the pH of the liquid component can be suppressed to a relatively low level. This makes it easier for the dielectric layer to be repaired, and thus a high withstand voltage can be ensured.

[0041] (2) In the above (1), the first carboxylic acid compound has a second linking group, and the second linking group can link the second carbonyl groups of the plurality of first sites to each other. In this case, the first carboxylic acid compound can easily act on the conductive polymer, and the conductive polymer is further stabilized, thereby further reducing the change in ESR over time. In addition, it is easy to introduce a plurality of first sites into the first carboxylic acid compound.

[0042] (3) In the above (2), the second linking group may have an oxygen atom or an amino group bonded to the second carbonyl group. In this case, the first site can be easily introduced into the first carboxylic acid compound via the oxygen atom or the amino group.

[0043] (4) In any one of (1) to (3) above, in one molecule of the first carboxylic acid compound, at least two of the first linking groups at the first site may have the same structure. In this case, the molecular design and synthesis of the first carboxylic acid compound are relatively easy. In addition, it is considered that since the interval between the first carbonyl group or the first carboxyl group is determined to a certain extent, the first carboxylic acid compound is easy to act on the conductive polymer.

[0044] (5) In any one of the above (1) to (4), in the first linking groups of at least two of the first sites, the number of carbon atoms of the main chain connecting the first carbon atom of the first carbonyl group and the second carbonyl group may be 1 to 4. In this case, since the first carboxyl group and the second carbonyl group are relatively close to each other, a stabilized structure is easily obtained when the first carboxyl group is ionized, and the surrounding of the conductive polymer is easily kept acidic.

[0045] (6) In any one of (1) to (5) above, the first linking groups in at least two of the first sites may include a non-aromatic cyclic divalent group or an aromatic divalent group. In this case, the solubility of the first carboxylic acid compound in the solvent and the affinity for the dielectric layer can be easily adjusted. In addition, since the first carboxyl group is easily stabilized and the positions of the second carbonyl group and the first carboxyl group are easily fixed, the pH of the liquid component tends to be lowered.

[0046] (7) In any one of (1) to (5) above, in at least two of the first linking groups in the first site, the main chain connecting the first carbon atom of the first carbonyl group and the second carbon atom of the second carbonyl group may be an aliphatic divalent group. In this case, the liquid component can improve the function of repairing the dielectric layer and further improve the effect of reducing leakage current.

[0047] (8) In the above (7), the aliphatic divalent group may have a first substituent, and the aliphatic divalent group may have a monovalent aliphatic hydrocarbon group having 6 or more carbon atoms as at least one of the first substituents. In this case, the effect of suppressing the esterification of the first carboxyl group is improved, and it is easy to ensure higher conductivity of the conductive polymer. In addition, the withstand voltage of the electrolytic capacitor can be further improved.

[0048] (9) In the above (8), the aliphatic divalent group may have the monovalent aliphatic hydrocarbon group at the α position of the first carbonyl group. The steric hindrance of the aliphatic hydrocarbon group further improves the effect of suppressing esterification of the first carboxyl group, thereby improving the effect of suppressing ESR fluctuation.

[0049] (10) In any one of (1) to (9) above, the acid component may further include a second carboxylic acid compound different from the first carboxylic acid compound. In this case, in addition to being easy to lower the pH of the liquid component, a certain degree of withstand voltage can be ensured by the first carboxylic acid compound, and the change in ESR over time can be further reduced.

[0050] (11) In any one of (1) to (10) above, the first carboxylic acid compound may account for 20% by mass or more of the acid component. In this case, the effect of suppressing the change of ESR over time is further improved. In addition, it is easy to ensure a higher withstand voltage.

[0051] (12) In any one of the above (1) to (11), the liquid component may further contain an alkali component. In this case, the dissociation of the acid component is improved, and higher conductivity of the conductive polymer is easily obtained.

[0052] (13) In the above (12), the equivalent ratio of the first carboxylic acid compound to the base component may be 0.4 or more and 10 or less. In this case, a high degree of dissociation of the first carboxylic acid compound can be ensured. In addition, corrosion of the electrode can be suppressed, and high withstand voltage can be easily ensured.

[0053] The electrolytic capacitor of the present invention will be described in more detail below. At least one selected from the following constituent elements may be arbitrarily combined with at least one of the above (1) to (13) of the solid electrolytic capacitor of the present invention as long as they are technically combinable.

[0054] (Liquid ingredients)

[0055] The liquid component contained in the electrolytic capacitor includes an acid component and a solvent. The acid component includes a first carboxylic acid compound.

[0056] (Acid component)

[0057] (First carboxylic acid compound)

[0058] In the first carboxylic acid compound, the plurality of first sites each independently have a first carboxyl group including a first carbonyl group; a second carbonyl group; and a first connecting group connecting them. The stability of the conductive polymer is improved by the first carboxyl group and the second carbonyl group of each of the plurality of first sites, and the high conductivity is maintained, thereby reducing the time-dependent change of the ESR of the electrolytic capacitor. In addition, the film repairability of the dielectric layer is improved by the action of the first carboxylic acid compound, and the increase of the leakage current can be suppressed even after long-term use, and a high withstand voltage can be ensured.

[0059] In one molecule of the first carboxylic acid compound, the structures of the first linking groups at multiple first positions may be all different, or the structures of the first linking groups at at least two first positions may be identical. The compound of such structure is all included in the first carboxylic acid compound of the present invention. It is believed that when the first linking groups at at least two first positions have identical structures, since the interval of the first carbonyl or the first carboxyl is determined to a certain extent, the first carboxylic acid compound is easy to act on conductive polymers, which is advantageous from the viewpoint of the stability and high conductivity of conductive polymers. In addition, the molecular design and synthesis of the first carboxylic acid compound are relatively easy. It should be noted that, when the structures of the first linking groups are identical, the structure of the part including the first carbonyl, the first linking group and the second carbonyl is arranged as the same situation.

[0060] In an electrolytic capacitor, the first carboxyl group may be in any of the following forms: free, salt, anionic, and in a form that interacts with a conductive polymer (complexation, etc.). In this specification, the first carboxyl group includes all forms thereof. For example, in two first sites, the case where the structures of the first connecting groups of the first sites are the same refers to the case where the structures of the two first sites are the same. However, in the case where the structures of the two first sites are the same, both the case where the forms of the first carboxyl groups are the same and the case where the forms of the first carboxyl groups are different are included.

[0061] The first carboxylic acid compound may have a second linking group. In the first carboxylic acid compound, the second linking group connects the second carbonyl groups of the respective first positions to each other. It can be considered that through the second linking group, the multiple carboxyl groups of the first carboxylic acid compound exist at intervals separated to a certain extent, and therefore easily act on the conductive polymer. Therefore, the conductive polymer is further stabilized, and the time-dependent change of ESR can be further reduced. In addition, by making the second linking group between the second carbonyl groups of the multiple first positions, it is easy to introduce multiple first positions into the first carboxylic acid compound.

[0062] The first carboxylic acid compound includes, for example, a compound represented by the following formula (IA).

[0063] [Chemical formula 1]

[0064]

[0065] (Where X 1 is the first carbonyl group, X 2 is the second carbonyl group, Y 1 is the first carboxyl group, R 1 is the first connecting group, R 2 is the second connecting group, Z 1 is the first part. k represents the first part Z 1 The number is an integer greater than 2.

[0066] k may be an integer of 2 to 8, an integer of 2 to 6, an integer of 2 to 4, or 2 or 3. In formula (IA), the structures of at least two first sites may be the same or all different. It should be noted that in formula (IA), the first carboxyl group is shown as a free form, but in the compound of formula (IA), each first carboxyl group is also included in a form other than a free form.

[0067] The first carboxylic acid compound includes, for example, a compound represented by the following formula (I): Among the compounds represented by formula (IA), a compound having two first sites is represented by formula (I).

[0068] [Chemical formula 2]

[0069]

[0070] (Where X 1 are the first carbonyl group, X 2 are the second carbonyl group, Y 1 are the first carboxyl group, R 1 Each independently represents the first linking group, R 2 is the second connecting group, Z 1 Each is independently the first part. )

[0071] It should be noted that, when the at least two first linking groups are of the same structure, in addition to the first carbonyl group, the first linking group and the second carbonyl group having the same structure in the structural formula of the first carboxylic acid compound, it also includes the case where the second linking group is the center and has a symmetrical structure. When the above formula (I) is used as an example to explain more specifically, the former is equivalent to the second linking group R 2 -X on the left side of 1 -R 1 -X 2 - part and -X on the right 2 -R 1 -X 1-partially in the same structure in such an arrangement. The latter is equivalent to the second connecting group R 2 -X on both the left and right sides 2 -R 1 -X 1 - Some of the cases have the same structure as the arrangement.

[0072] The compound of formula (I) has a second connecting group R 2 The center may be symmetrical (line symmetrical) or asymmetrical. In formula (I), the first carboxyl group is shown as an example in a free state, but the compound of formula (I) also includes a state other than a free state of each first carboxyl group. In the above-mentioned second connecting group R 2 In the case of centrosymmetry, the first carboxyl groups may be in different forms.

[0073] The first linking group (R in formula (IA) and formula (I) 1 ) and the second linking group (in formula (IA) and formula (I), R 2 ) The respective structures are not particularly limited as long as they do not hinder the effects of the first carboxyl group and the second carbonyl group on the conductive polymer. The first site may be, for example, a residue of a polycarboxylic acid or its anhydride. In addition, a plurality of second carbonyl groups and a second connecting group connecting them may be a residue of a polycarboxylic acid or its anhydride. As these polycarboxylic acids, for example, dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids (particularly dicarboxylic acids) may be cited. In the case where the first site is a residue of a polycarboxylic acid or its anhydride, the second connecting group is a residue of a compound (for example, a polyol compound, a polyamine compound) that can be connected to a polycarboxylic acid or its anhydride. In the case where a plurality of second carbonyl groups and a second connecting group connecting them are residues of polycarboxylic acids or their anhydrides, the first connecting group and the first carboxyl group are residues of a compound (for example, a hydroxycarboxylic acid compound, an aminocarboxylic acid compound) that can be connected to a polycarboxylic acid or its anhydride. From the viewpoint of easy molecular design or synthesis of the first carboxylic acid compound, it is preferred that the first site is a residue of a polycarboxylic acid (particularly dicarboxylic acid) or its anhydride.

[0074] A plurality of first linking groups (R in formula (IA) and formula (I) 1) may have a main chain and a substituent (including a side chain) bonded to the main chain, or may consist of only the main chain (equivalent to a case where there is no substituent). Hereinafter, the substituent (including a side chain) bonded to the main chain is sometimes referred to as the first substituent. The main chain connects the carbon atom of the first carbonyl group (the first carbon atom) and the carbon atom of the second carbonyl group (the second carbon atom). The main chain contains at least carbon atoms and is a straight-chain part, and the first carbon atom and the second carbon atom are not included in the main chain. In addition, the first substituent is not included in the main chain. It should be noted that the main chain also includes the case where the number of carbon atoms in the main chain is 1 (for example, a methylene group, a methylene group having a first substituent, a group having a methylene group and a hetero atom described later (oxymethylene, an oxymethylene group having a first substituent, etc.)). In the case where there are multiple chains connecting the first carbon atom and the second carbon atom, the chain with the least number of atoms (carbon atoms, hetero atoms described later, etc.) constituting the chain is the main chain. In addition, the first substituent may further have a substituent (second substituent).

[0075] The main chain may be a hydrocarbon chain or may contain heteroatoms. As heteroatoms, at least one selected from oxygen atoms, sulfur atoms, nitrogen atoms and silicon atoms is included. The main chain may contain one heteroelement or two or more heteroelements. In addition, the main chain may be linear or may constitute a part of a ring structure. The main chain may constitute a part of at least one ring structure selected from non-aromatic rings and aromatic rings. These rings may be hydrocarbon rings or heterocycles containing heteroelements. In addition, these rings may be bridged rings or condensed rings. As heteroatoms contained in the heterocycle, at least one selected from oxygen atoms, sulfur atoms and nitrogen atoms may be included. The heterocycle may contain one heteroelement or two or more heteroelements. As heterocycles, divalent groups corresponding to the heterocyclic groups described in the first substituent described later may be included, and the description of the heterocycle of the first substituent may be referred to.

[0076] For example, when the first linking group is 1,1-dimethylethane-1,2-diyl, 1,2-ethylene forms the main chain except for the two methyl groups corresponding to the substituent. When the first carbonyl group and the second carbonyl group are bonded to the 1 and 2 positions of cyclohexane, the connection of the carbon atoms at the 1 and 2 positions of cyclohexane becomes the main chain, and the number of carbon atoms in the main chain is 2. In this case, the first linking group is cyclohexane-1,2-diyl. When the first linking group is 2-norbornene-5,6-diyl, the connection of the carbon atoms at the 5 and 6 positions of the norbornene ring becomes the main chain, and the number of carbon atoms in the main chain is 2. When the first linking group is 1,2-phenylene, the connection of the carbon atoms at the 1 and 2 positions of the benzene ring becomes the main chain, and the number of carbon atoms in the main chain is 2. As the main chain, alkylene, alkenylene, oxyalkylene, polyoxyalkylene, etc. are suitable. These groups can constitute part of the ring structure. In addition, in an oxyalkylene group or a polyoxyalkylene group, an oxy group is bonded to the second carbon atom, and an alkylene group is bonded to the first carbon atom.

[0077] In each first linking group, the carbon number of the main chain can be more than 1 and less than 10, can also be more than 1 and less than 6, can also be more than 1 and less than 4. In the first linking groups of at least 2 first positions, the carbon number of the main chain is preferably more than 1 and less than 4, can also be more than 2 and less than 4. In the case where the carbon number of the main chain is less than 4, since the interval between the first carboxyl group and the second carbonyl group is relatively close, it is easy to obtain a stabilized structure when the first carboxyl group is ionized, and it is easy to keep the surrounding of the conductive polymer acidic. Therefore, the deterioration of the conductive polymer is suppressed, and the effect of maintaining high conductivity is further improved. In the first carboxylic acid compound, the carbon number of the main chain of the first linking group of at least 2 first positions can be the same, and the carbon number of the main chain of the first linking group of the first position can also be all different.

[0078] The first linking group may include a cyclic divalent group (a non-aromatic cyclic divalent group or an aromatic divalent group, etc.). These cyclic divalent groups may be included in at least two first linking groups. These cyclic divalent groups may be divalent hydrocarbon ring groups or divalent heterocyclic groups. When the first linking group includes such a cyclic divalent group, it is easy to adjust the solubility of the first carboxylic acid compound in the solvent and the affinity for the dielectric layer. When the first linking group has such a cyclic divalent group, as the volume of the ring increases, the first carboxyl group is easily stabilized, and the positions of the second carbonyl group and the first carboxyl group are easily fixed. Therefore, the pH of the liquid component tends to become lower, and it is easy to stabilize the conductive polymer. For example, the first linking group may include a non-aromatic or aromatic divalent hydrocarbon ring group (cyclohexane-1,2-diyl, 2-norbornene-5,6-diyl, 1,2-phenylene, etc.), a non-aromatic or aromatic divalent heterocyclic group. The non-aromatic cyclic divalent group or the aromatic divalent group may further have a substituent (third substituent). In addition, the first connecting group may be a structure in which a non-aromatic cyclic divalent group or an aromatic divalent group is bonded to an aliphatic divalent group. The aliphatic divalent group constitutes a part of the main chain of the first connecting group. The first connecting group may be a structure in which one non-aromatic cyclic divalent group or an aromatic divalent group is bonded to one aliphatic divalent group, or may be a structure having one non-aromatic cyclic divalent group or an aromatic divalent group and two aliphatic divalent groups respectively bonded to each connecting bond of the divalent group. The aliphatic divalent group may have a first substituent.

[0079] It is also preferred that the main chain of the first connecting group is an aliphatic divalent group. In at least two first connecting groups at the first position, the main chain may be an aliphatic divalent group. In these cases, the liquid component can improve the function of repairing the dielectric layer, and the effect of reducing the leakage current when a high voltage is applied is further improved. The aliphatic divalent group may have a first substituent.

[0080] Examples of the first substituent of the main chain of the first linking group include a hydrocarbon group, a heterocyclic group, and R 3 -O-group (alkoxy group, etc.), R 4 -OC(=O)- group (alkoxycarbonyl, etc.), R 5 -C(=O)- group (acyl group, etc.), carboxyl group, hydroxyl group, halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). The first substituent is usually a monovalent group. 3 , R 4 and R 5 , respectively, hydrocarbon groups can be mentioned.

[0081] The hydrocarbon group as the first substituent, as R 3 , R 4and R 5 The hydrocarbon groups may be saturated or unsaturated. Examples of these hydrocarbon groups include non-aromatic hydrocarbon groups (aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, etc.), aromatic hydrocarbon groups, etc. The aliphatic hydrocarbon group may be straight-chain or branched. Examples of aliphatic hydrocarbon groups include alkyl groups and unsaturated aliphatic hydrocarbon groups (alkenyl groups, dienyl groups, trienyl groups, etc.). Examples of alkyl groups include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, sec-butyl groups, tert-butyl groups, pentyl groups, hexyl groups, heptyl groups, n-octyl groups, 2-ethylhexyl groups, nonyl groups, decyl groups, undecyl groups, lauryl groups (dodecyl groups), myristyl groups, etc. Examples of unsaturated aliphatic hydrocarbon groups include vinyl groups, allyl groups, hexenyl groups, 2-octenyl groups, 2,4,6-trimethylnon-2-en-1-yl groups, decenyl groups, dodecenyl groups (including 2-dodecenyl groups and tetrapropenyl groups), and tetradecenyl groups. The number of carbon atoms of the aliphatic hydrocarbon group (monovalent aliphatic hydrocarbon group) may be 1 or more, or 6 or more. The number of carbon atoms of the aliphatic hydrocarbon group (monovalent aliphatic hydrocarbon group) may be 12 or less, 8 or less, or 5 or less. The number of carbon atoms of the aliphatic hydrocarbon group (monovalent aliphatic hydrocarbon group) may be 1 or more and 12 or less, 1 or more and 8 or less, 1 or more and 5 or less, or 6 or more and 12 or less. Examples of the alicyclic hydrocarbon group include cycloalkyl (cyclohexyl, etc.), cycloalkenyl (cyclohexenyl, etc.), cyclodienyl (cyclopentadienyl, etc.), and bridged hydrocarbon groups (norbornyl, norbornyl, dicyclopentadienyl, etc.). The number of carbon atoms of the alicyclic hydrocarbon group may be 5 or more and 16 or less, 5 or more and 12 or less, or 5 or more and 10 or less. Examples of the aromatic hydrocarbon group include aryl (phenyl, naphthyl, etc.). The number of carbon atoms in the aromatic hydrocarbon group may be 6 or more and 14 or less, or 6 or more and 10 or less.

[0082] The heterocyclic group as the first substituent is a monovalent heterocyclic group containing a heteroatom as a constituent atom of the ring. As the heteroatom, for example, at least one selected from an oxygen atom, a sulfur atom and a nitrogen atom can be cited. The heterocyclic group can contain one heteroatom or two or more heteroatoms. The heterocyclic group can be saturated or unsaturated. The heterocyclic group can be non-aromatic or aromatic. The heterocyclic group can be, for example, more than 5 members and less than 14 members, or more than 5 members and less than 10 members. As the heterocyclic group, oxygen-containing ring groups (furanyl, tetrahydrofuranyl, etc.), sulfur-containing ring groups (thiophene-3-yl, etc.), nitrogen-containing ring groups (pyrrolidinyl, piperidinyl, pyridinyl, morpholinyl, etc.), etc. can be cited.

[0083] In the case where the main chain of the first connecting group is an aliphatic divalent group, the aliphatic divalent group may have a monovalent aliphatic hydrocarbon group with a carbon number of 6 or more as at least one of the first substituents. In at least two first connecting groups at the first position, the main chain is an aliphatic divalent group, and at least one of the first substituents may have a monovalent aliphatic hydrocarbon group with a carbon number of 6 or more. In these cases, the withstand voltage of the electrolytic capacitor can be further improved. In addition to the low effect of lowering the pH of the liquid component, the first carboxylic acid compound whose main chain is an aliphatic divalent group also has a tendency for the first carboxyl group to be easily esterified. By having at least one of the first substituents be an aliphatic hydrocarbon group with a carbon number of 6 or more, the effect of inhibiting esterification is improved, and a higher conductivity of the conductive polymer can be ensured. The first connecting group preferably has a first substituent at the α position of the first carbonyl group. In the case where the first connecting group has an aliphatic hydrocarbon group with a carbon number of 6 or more as the first substituent at the α position of the first carbonyl group, the effect of inhibiting the esterification of the first carboxyl group is further improved by the steric hindrance of the group. Therefore, the effect of the first carboxylic acid compound on the conductive polymer is maintained, and the effect of suppressing ESR fluctuation is improved.

[0084] It should be noted that, not limited to the case of an aliphatic hydrocarbon group having 6 or more carbon atoms, when there is a first substituent that can be a steric hindrance at the α position of the first carbonyl group, it is easy to obtain a good effect of suppressing ESR fluctuations as in the above case. For example, there may be two first substituents at the α position of the first carbonyl group. In addition, there may be a first substituent such as a tert-butyl group, a cyclic group (alicyclic hydrocarbon group, aromatic hydrocarbon group, heterocyclic group, etc.) at the α position of the first carbonyl group. In addition, there may be an alkyl group (alkyl group having 1 or more and 3 or less carbon atoms, etc.) having a cyclic group (alicyclic hydrocarbon group, aromatic hydrocarbon group, heterocyclic group, etc.) as the second substituent at the α position of the first carbonyl group as the first substituent.

[0085] The number of the first substituents per one first linking group is, for example, greater than 1. The upper limit of the number of the first substituents per one first linking group is not particularly limited and can be determined according to the length of the main chain. The number of the first substituents can be less than 6 or less than 3.

[0086] When the first substituent is a hydrocarbon group, the second substituent may be, for example, at least one selected from hydrocarbon groups other than the first substituent and groups (or atoms) other than hydrocarbon groups among the groups (or atoms) exemplified as the first substituent. When the first substituent is a heterocyclic group, the second substituent may be at least one selected from groups (or atoms) other than heterocyclic groups among the groups (or atoms) exemplified as the first substituent.

[0087] The third substituent can be selected from the substituents exemplified for the first substituent or the second substituent.

[0088] As the polycarboxylic acid corresponding to the first site, succinic acid, succinic acid having an alkyl group or an alkenyl group as the first substituent (2,2-dimethylsuccinic acid, 2-n-butylsuccinic acid, 2-n-octylsuccinic acid, 2-n-dodecylsuccinic acid, 2-(2'-octenyl)succinic acid, 2-(2'-dodecenyl)succinic acid, etc.), polycarboxylic acid having an alicyclic hydrocarbon group as the first substituent (2-n-cyclohexylsuccinic acid, etc.), polycarboxylic acid having an aromatic hydrocarbon group as the first substituent (2-phenylsuccinic acid, etc.), polycarboxylic acid having a cyclic divalent group as the first connecting group (1,2-cyclohexanedicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid, phthalic acid, etc.) can be exemplified. When forming the first site, the anhydrides of these polycarboxylic acids can be used. However, these are only examples, and the polycarboxylic acid or its anhydride corresponding to the first site is not limited to these.

[0089] The second linking group is preferably a residue of a polyol compound or a polyamine compound. Such a second linking group has an oxygen atom or an amino group bonded to the second carbonyl group of each first linking group. In this case, the first site can be easily introduced into the first carboxylic acid compound through an ester bond or an amide bond. The amino group includes, for example, >N- and -NH-.

[0090] The valence of the second linking group corresponds to the number of first sites possessed by the first carboxylic acid compound (k in formula (IA)). For example, when the first carboxylic acid compound has two first sites, the second linking group is a divalent group. When the first carboxylic acid compound has three or four first sites, the second linking group is a trivalent group or a tetravalent group, respectively.

[0091] The second connecting group may be a chain group or may include a ring structure. The ring structure may constitute a part of the main chain of the second connecting group. In addition, the second connecting group may have a main chain and a substituent (the fourth substituent) bonded to the main chain. The second connecting group may have a ring structure (cyclic group) as the fourth substituent. The second connecting group may be saturated or unsaturated. The ring structure may be saturated or unsaturated. In addition to the oxygen atom or amino group bonded to the second carbonyl group, the second connecting group may also include a heteroatom in the main chain. As heteroatoms, oxygen atoms, nitrogen atoms, etc. may be cited. As the fourth substituent, it can be selected from the substituents exemplified as the first substituent or the second substituent, an oxo group (=O), etc. In the case where the second connecting group includes a fourth substituent, the number of the fourth substituent is, for example, 1 or more, 1 or more and 6 or less, or 1 or more and 4 or less.

[0092] As the polyol compound corresponding to the second connecting group, for example, aliphatic polyols (alkane polyols, olefin diols, etc.), alicyclic polyols, aromatic polyols, and alkylene oxide adducts of these polyols, and polyalkylene glycols can be cited. As alkane polyols, alkane diols (ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 2-ethyl-1,3-hexanediol, 1,9-nonanediol, 2-butyl-2-ethyl-1,3-propanediol, etc.), glycerol, polyglycerol (diglycerol, triglycerol, tetraglycerol, etc.), trimethylolpropane, sugars or sugar alcohols (mannitol, erythritol, xylitol, pentaerythritol, etc.) can be cited. The number of carbon atoms of the alkane polyol can be greater than 1 and less than 12, or can be greater than 1 and less than 10 (or less than 9). Within these ranges, the number of carbon atoms can be greater than 2. Examples of olefin diols include 1,4-dihydroxybut-2-ene. The number of carbon atoms in the olefin diol may be, for example, 2 or more and 12 or less, or 2 or more and 10 or less (or 9 or less). Examples of polyalkylene glycols include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, etc. Examples of polyalkylene glycols include poly(C 2-4 Alkylene glycol). In the polyalkylene glycol, the number of repetitions of the oxyalkylene group (oxyalkylene groups having 2 to 4 carbon atoms) is 2 or more, 2 to 10 or more, or 2 to 6 or less. Specific examples of polyethylene glycol include diethylene glycol and triethylene glycol. Specific examples of polypropylene glycol include dipropylene glycol and tripropylene glycol. Specific examples of polytrimethylene glycol include di(trimethylene glycol) and tri(trimethylene glycol). The alicyclic polyols include polyhydroxycycloalkanes (polyhydroxycycloalkanes having 5 to 10 carbon atoms such as dihydroxycyclohexane and trihydroxycyclohexane) and polyhydroxycycloolefins (polyhydroxycycloolefins having 5 to 10 carbon atoms such as dihydroxycyclohexene) and the like, as well as poly(hydroxyalkyl)cycloalkanes (poly(hydroxyC 1-4 Alkyl) C 5-10 Cycloalkanes, etc.). Aromatic polyols include dihydroxybenzene, biphenol, bisphenol, etc., as well as poly(hydroxyalkyl) aromatic hydrocarbons (poly(hydroxy C 1-4 Alkyl) C 6-10 Aromatics, etc.).

[0093] Examples of the alkylene oxide adduct include products obtained by adding one or more or two or more alkylene oxides (such as ethylene oxide and propylene oxide) to each hydroxyl group of the above-mentioned polyol. 2-4The number of alkylene oxides added to each hydroxyl group is, for example, 6 or less, 4 or less, or 3 or less. The lower limit and upper limit of the number of alkylene oxides can be combined arbitrarily. In the first carboxylic acid compound, the first site can be introduced into all hydroxyl groups of the polyol compound corresponding to the second linking group, or the first site can be introduced into a part of the hydroxyl groups.

[0094] In the polyamine compound corresponding to the second connecting group, it is preferred that at least two amino groups are amino groups having active hydrogen (>NH, -NH2). Examples of the polyamine compound corresponding to the second connecting group include aliphatic polyamines, polyalkylene polyamines, alicyclic polyamines, aromatic polyamines, cyclic amines, and the like. Examples of aliphatic polyamines include alkylenediamines (ethylenediamine, 1,4-diaminobutane, N,N'-dialkylalkylenediamine, etc.), triaminoalkanes, tetraaminoalkanes, and the like. Examples of alkylenediamines include C 2-6 Alkylene diamines (e.g., C 2-4 Examples of N,N'-dialkyl alkylene diamines include N,N'-dialkyl ethylene diamine and the like. 1-6 Alkyl-C 2-6 Alkylene diamines (e.g., N,N'-diC 1-4 Alkyl-C 2-4 Specific examples of N,N'-dialkyl alkylene diamines include N,N'-diethylethylenediamine, N,N'-diisopropylethylenediamine, and N,N'-di-tert-butylethylenediamine. The carbon number of the aliphatic polyamine may be 1 to 10, or 2 to 6. Examples of the alicyclic polyamines include polyaminocycloalkanes (polyamino C such as diaminocyclohexane, etc.). 5-10 Cycloalkanes, etc.), polyaminocycloolefins (polyamino C 5-10 Examples of aromatic polyamines include polyamino aromatics (polyamino C such as 1,4-phenylenediamine and triaminobenzene). 6-10 Aromatic hydrocarbons, etc.) and the like. Examples of cyclic amines include compounds having an -NH group and at least one -NH group or -NH2 group. Examples of such compounds include cyclic amines having an amino group as a substituent (cytosine, guanine, adenine, etc.) and cyclic polyamines (piperazine, thymine, uracil, etc.). Cyclic amines may be 5-12-membered or 5-10-membered.

[0095] The liquid component may contain, for example, at least one selected from the group consisting of a compound represented by the following formula (Ia) and a compound represented by the following formula (Ib) as the first carboxylic acid compound.

[0096] [Chemical formula 3]

[0097]

[0098] (Where R 1a ~R 1h , R 1j and R 1k , and R 1m and R 1n Each independently represents a hydrogen atom or a first substituent, and n1 to n4 correspond to the number of repetitions of the methylene chain that may have the first substituent. 1a and Ring Z 1b Each independently represents a cyclic divalent group (a non-aromatic cyclic divalent group or an aromatic divalent group, etc.) contained in the first linking group. 3a and R 3b Ring Z 1a and Ring Z 1b The third substituent m1 and m2 respectively correspond to the number of the third substituents in each ring. 2 is the second connecting group.

[0099] Formula (Ia) corresponds to the case where the main chain of the first linking group in formula (I) is an aliphatic divalent group. n1 and n2 are integers greater than 0, and may be integers greater than 1. (n1+1) and (n2+1) correspond to the number of carbon atoms in the main chain of the first linking group. n1 and n2 may be, for example, greater than 1 and less than 5, or greater than 1 and less than 3, respectively. When n1 is greater than 2, the number of R atoms bonded to each carbon atom of the main chain is 1c At least two of them may be the same or all may be different. Similarly, when n1 is 2 or more, the R bonded to each carbon atom of the main chain is 1d At least two of them may be the same or all may be different. Similarly, when n2 is 2 or more, the number of R bonded to each carbon atom of the main chain is 1g (or R 1h ) may be the same or all may be different.

[0100] The compound of formula (Ia) preferably has a first substituent at least at the α-position of the first carbonyl group. 1a and R 1b At least one of them is the first substituent. 1e and R 1f At least one of them is the first substituent. It is preferred that at the α position of the first carbonyl group, in addition to the aliphatic hydrocarbon group having 6 or more carbon atoms, there is at least one first substituent that can become a steric hindrance. In this case, R 1a and R 1b One of them is an aliphatic hydrocarbon group having 6 or more carbon atoms or a first substituent group that can be sterically hindered, and the other is a hydrogen atom.1e and R 1f One of them is an aliphatic hydrocarbon group having 6 or more carbon atoms or a first substituent that can be sterically hindered, and the other is a hydrogen atom. In these cases, regardless of the number of n1, R 1c and R 1d Each may be a hydrogen atom or a first substituent, R 1c and R 1d Each may also be a hydrogen atom. Similarly, regardless of the number of n2, R 1g and R 1h Each may be a hydrogen atom or a first substituent, R 1g and R 1h Each may be a hydrogen atom.

[0101] Formula (Ib) corresponds to the case where the first linking group in formula (I) includes a non-aromatic cyclic divalent group or an aromatic divalent group. n3 and n4 are integers greater than 0. In n3 (or n4), ring Z is added 1a (or Ring Z 1b ) is equivalent to the number of carbon atoms in the main chain of the first linking group. n3 and n4 can be, for example, 0 to 4 or 0 to 2, respectively. When n3 (or n4) is 2 or more, the number of R atoms bonded to each carbon atom of the main chain is 1j (or R 1m ) may be the same or all different. Similarly, when n3 (or n4) is 2 or more, the R bonded to each carbon atom of the main chain is 1k (or R 1n ) may be the same or all may be different.

[0102] In formula (Ib), m1 and m2, which correspond to the number of the third substituent, are each an integer greater than or equal to 0. The upper limit of the number of the third substituent can be determined based on the number of the ring Z. 1a or Ring Z 1b In the ring Z 1a (or Ring Z 1b ) has multiple third substituents R 3a In the case of multiple R 3a At least two of them may be the same, or all of them may be different.

[0103] The compound represented by formula (Ib) may be, for example, a compound represented by the following formula (ib).

[0104] [Chemical formula 4]

[0105]

[0106] (wherein, ring Z 1cand Ring Z 1d Each independently represents a non-aromatic cyclic divalent group or an aromatic divalent group contained in the first linking group. 1j and R 1k , R 1m and R 1n 、n3、n4、R 3a , R 3b , m1, m2 and R 2 Same as above.)

[0107] In formula (ib), (n3+2) and (n4+2) respectively correspond to the number of carbon atoms in the main chain of the first linking group.

[0108] In each of Formula (Ia) and Formula (Ib) (including Formula (ib)), the structures of the two first linking groups may be the same (including the case where they are line-symmetrical about the second linking group) or different.

[0109] In each of Formula (Ia) and Formula (Ib) (including Formula (ib)), regarding the second linking group R 2 , the description of the second connecting group mentioned above can be referred to. The second connecting group R 2 For example, the divalent group may be any one of the following (iia) to (iid). In these divalent groups, * represents a bond with the first carbonyl group and the second carbonyl group.

[0110] [Chemical formula 5]

[0111]

[0112] The second linking group represented by formula (iia) corresponds to the residue of the above-mentioned polyol compound (diol compound, etc.). The second linking group represented by formulas (iib) to (iid) corresponds to the residue of the above-mentioned polyamine compound. 2a It can be a chain group or a group containing a ring structure. 2a The above-mentioned fourth substituent may be present. Formulae (iic) and (iid) are groups corresponding to the above-mentioned cyclic amines. 4a , R 4b and R 4e are each independently a hydrogen atom or a fourth substituent. 2a and Ring Z 2b R corresponds to the ring structure contained in the second linking group (specifically, a nitrogen-containing ring). 4c and R 4d Each independently is ring Z 2a and Ring Z 2b The fourth substituent R 4c The number of p1 and represents the fourth substituent R4d The number of q1 is an integer greater than 0. The upper limit of p1 and q1 can be determined according to the ring Z 2a and Ring Z 2b The respective numbers are determined.

[0113] In formula (I), (Ia), (Ib) and (ib), the case where the second linking group is a divalent group and has two first sites is exemplified, but the first carboxylic acid compound is not limited to these cases. The first carboxylic acid also includes a compound in which the second linking group is a trivalent or higher polyvalent group (for example, a residue of a polyol compound having three or more hydroxyl groups, a residue of a polyamine compound having three or more amino groups) and has at least two first sites. For such compounds, the description of formula (I), (Ia), (Ib) and (ib) can also be referred to. In such a compound, at least two of the two or more first sites may be the same or all different.

[0114] In the first carboxylic acid compound, when the second linking group is a residue of a polyol compound or a residue of a polyamine compound, each hydroxyl group or each amino group not bonded to the first site may be in a free form. In addition, each hydroxyl group or each amino group not bonded to the first site may be etherified, esterified, form an amide bond, form a salt, or be protected. Each hydroxyl group or each amino group not bonded to the first site may interact or bond with a component present in the production process, or may interact or bond with other components contained in the electrolytic capacitor.

[0115] The acid component may contain one type of the first carboxylic acid compound, or may contain two or more types in combination.

[0116] (Second carboxylic acid compound)

[0117] The acid component may further include a second carboxylic acid compound different from the first carboxylic acid compound. When the acid component includes the second carboxylic acid compound, the pH of the liquid component can be further reduced, and thus, a certain degree of withstand voltage is ensured by the action of the first carboxylic acid compound, and the reduction in the conductivity of the conductive polymer is further suppressed, so it is easy to further reduce the time-dependent change of ESR.

[0118] Examples of the second carboxylic acid compound include carboxylic acids other than the first carboxylic acid compound, carboxylic acid anhydrides, coordination compounds of carboxylic acids, carboxylic acid compounds having one first site (second carboxylic acid compound B), etc. Second carboxylic acid compounds other than the second carboxylic acid compound B are sometimes referred to as second carboxylic acid compounds A.

[0119] In the second carboxylic acid compound A, as the above-mentioned carboxylic acid, aliphatic carboxylic acid, aromatic carboxylic acid, etc. can be cited. As aromatic carboxylic acid, aromatic hydroxy acid (benzoic acid, salicylic acid, etc.), aromatic polycarboxylic acid (phthalic acid, pyromellitic acid, etc.), sulfoaromatic carboxylic acid (p-sulfobenzoic acid, 3-sulfophthalic acid, 5-sulfosalicylic acid, etc.) can be cited. As the above-mentioned coordination compound, for example, a coordination compound formed by the acid bonding of at least one central atom selected from boron, aluminum and silicon and the carbonyl oxygen bond bonded to the central atom can be cited. As a specific example of the coordination compound, boron disalicylic acid, boron dioxalic acid, boron diglycolic acid, boron digallic acid can be cited.

[0120] The second carboxylic acid compound B, for example, comprises a first site and an organic group bonded to the first site. 2b -X- represents a group. -X- is, for example, -O-, or -N (-R 4f )-, and is bonded to the second carbonyl group of the first site. The organic group may be a residue of a hydroxyl compound (monohydroxyl compound or polyol compound) or a residue of an amine compound (monoamine compound or polyamine compound). 4f , please refer to the information about R 4a , R 4b Description. 4f It can be a hydrogen atom or a fourth substituent. The organic group can be a second connecting group (e.g., R 2 ) corresponds to a monovalent group.

[0121] About the second carboxylic acid compound B, the description of the first part and the second connecting group of the first carboxylic acid compound can be referred to. As the second carboxylic acid compound B, monoesters of alkylene glycol or polyalkylene glycol and polycarboxylic acid (monoesters of ethylene glycol and octenyl succinic acid, monoesters of triethylene glycol and octenyl succinic acid, monoesters of tripropylene glycol and octenyl succinic acid, monoesters of triethylene glycol monomethyl ether and octenyl succinic acid, monoesters of ethylene glycol and 1,2-cyclohexanedicarboxylic acid, monoesters of ethylene glycol and phthalic acid, etc.), monoesters of monohydric alcohol and polycarboxylic acid (monoisodecyl ester of octenyl succinic acid, etc.), monoamides of monoamine and polycarboxylic acid (monoamides of diethylamine and octenyl succinic acid, etc.), monoamides of polyamine and polycarboxylic acid (monoamides of ethylenediamine and octenyl succinic acid, etc.), etc. can be cited. However, these are only exemplified, and the second carboxylic acid compound B is not limited to these.

[0122] The acid component may include one or more second carboxylic acid compounds. Among the second carboxylic acid compounds, aromatic carboxylic acids (phthalic acid, salicylic acid, benzoic acid, etc.) and the above-mentioned coordination compounds (boron disalicylic acid, boron dioxalic acid, boron diglycolic acid, etc.) are preferred, among which phthalic acid, salicylic acid, boron disalicylic acid, etc. are preferred. The acid component may include one or more second carboxylic acid compounds A. In addition, the acid component may include one or more second carboxylic acid compounds B.

[0123] In the liquid component, the carboxyl group and other acid groups (sulfonic acid group, phosphoric acid group, phosphonic acid group, etc.) possessed by the second carboxylic acid compound can be in any form of free form, salt form, anion form, and form formed by interaction (complexation, etc.) with the conductive polymer. The carboxyl group and other acid groups of the second carboxylic acid compound include all their forms.

[0124] (Other acids)

[0125] The acid component may include acids other than the first carboxylic acid compound and the second carboxylic acid compound. As such other acids, for example, acids other than carboxylic acids having a carbonyl oxygen bond (oxycarbonic acid, Michaelis acid, etc.) or their coordination compounds, phenolic compounds (picric acid, p-nitrophenol, pyrogallol, catechol, etc.) or their coordination compounds, sulfur-containing acids (sulfuric acid, sulfonic acid (aromatic sulfonic acid, etc.), oxyaromatic sulfonic acid (phenol-2-sulfonic acid, etc.), compounds with sulfonimide bonds, boron-containing acids (boric acid, halogenated boric acid (tetrafluoroboric acid, etc.), or their partial esters, etc.), phosphorus-containing acids (phosphoric acid, halogenated phosphoric acid (hexafluorophosphoric acid, etc.), phosphonic acid, phosphinic acid, or their partial esters, etc.), nitrogen-containing acids (nitric acid, nitrous acid, etc.).

[0126] Examples of the compound having a sulfonyl imide bond include saccharin, 1,2-benzenedisulfonyl imide, cyclohexafluoropropane-1,3-bis(sulfonyl)imide, 4-methyl-N-[(4-methylphenyl)sulfonyl]benzenesulfonamide, dibenzenesulfonyl imide, trifluoromethanesulfonanilide, N-[(4-methylphenyl)sulfonyl]acetamide, benzenesulfonylanilide, and N,N'-diphenylsulfamide.

[0127] As the coordination compound, for example, there can be mentioned a coordination compound formed by bonding at least one central atom selected from boron, aluminum and silicon to an acid or phenol compound having a carbonyl oxygen bond bonded to the central atom. As a specific example of the coordination compound, there can be mentioned boron dipyrocatechol and boron dipyrocatechol.

[0128] The acid component may contain one type of the above-mentioned other acids, or may contain two or more types.

[0129] The ratio of the first carboxylic acid compound in the acid component can be more than 20 mass %, or more than 33 mass %. In this case, the effect of suppressing the time-varying change of ESR is further improved. In addition, it is easy to ensure higher withstand voltage. The ratio of the first carboxylic acid compound in the acid component is less than 100 mass %, and it can be less than 80 mass % from the viewpoint of easily ensuring higher withstand voltage, the film repairability of the dielectric layer. These lower limits and upper limits can be arbitrarily combined.

[0130] The mass ratio of the second carboxylic acid compound to the first carboxylic acid compound (= second carboxylic acid compound / first carboxylic acid compound) may be 0 / 100 or more and 80 / 20 or less, or 20 / 80 or more and 67 / 33 or less. When the mass ratio is within such a range, the first carboxylic acid compound is more likely to function, and the effect of reducing the time-dependent change of ESR is improved while ensuring high withstand voltage.

[0131] The mass ratio of the second carboxylic acid compound B to the first carboxylic acid compound (= second carboxylic acid compound B / first carboxylic acid compound) may be 0 / 100 or more and less than 50 / 50, 0.1 / 99.9 or more and 30 / 70 or less, or 1 / 99 or more and 20 / 80 or less. When the mass ratio is within such a range, the time-dependent change of ESR and the leakage current can be suppressed to a lower level.

[0132] The above-mentioned ratio and mass ratio are values ​​obtained based on the mass of each acid in a free form.

[0133] (Oligomer component)

[0134] The liquid component may further include an oligomer component of the first carboxylic acid compound. When the oligomer component includes an oligomer having a carboxyl group, the oligomer is included in the second carboxylic acid compound. The oligomer, for example, has a repeating structure of a first site and a second connecting group. For example, when the second connecting group is a residue of a polyol compound, the oligomer has a structure in which a polycarboxylic acid or anhydride thereof corresponding to the first site is alternately connected to a polyol compound through an ester bond. When the second connecting group is a residue of a polyamine compound, the oligomer has a structure in which a polycarboxylic acid or anhydride thereof corresponding to the first site is alternately connected to a polyamine compound through an amide bond. The oligomer component may include one oligomer, or may include two or more oligomers having different structures or chain lengths.

[0135] (Alkali component)

[0136] The liquid component may further contain an alkali component. In this case, the dissociation of the acid component such as the first carboxylic acid compound is improved, and the acid group such as the carboxyl group is easily acted on the conductive polymer. Therefore, it is easy to obtain a higher conductivity of the conductive polymer.

[0137] Examples of the alkaline component include ammonia, amines (specifically, primary amines, secondary amines, and tertiary amines), quaternary ammonium compounds, and amidinium compounds. The liquid component may contain one type of alkaline component, or may contain two or more types of alkaline components.

[0138] Amines may be any of aliphatic, aromatic and heterocyclic. Examples of amines include dialkylamines (diethylamine, etc.), trialkylamines (trimethylamine, ethyldimethylamine, triethylamine (TEA), tri-n-butylamine (TBA), dimethyl-n-octylamine (DMOA), etc.), alkylenediamines (ethylenediamine, etc.), aromatic amines (aniline, etc.), heterocyclic amines (pyrrolidine, imidazole compounds (imidazole (Imd), 1,2,3,4-tetramethylimidazolinium, etc.), pyridine (Pyr), 4-dimethylaminopyridine, diazabicycloundecene (DBU), etc.). Aromatic amines and heterocyclic amines may each be monocyclic or polycyclic (condensed ring, bridged ring, etc.). Examples of quaternary ammonium compounds include amidine compounds (including imidazole compounds).

[0139] The liquid component may contain the alkali component in a free form, in a cationic form, or in a salt form. All of these forms may be referred to as alkali components.

[0140] The equivalent ratio of the first carboxylic acid compound to the alkali component (= the first carboxylic acid compound / alkali component) can be 0.4 or more and 10 or less, 0.4 or more and 8 or less, 0.4 or more and 5 or less, 0.4 or more and 4.0 or less, or 0.4 or more and 3.5 or less. In this case, a high degree of dissociation of the first carboxylic acid compound can be ensured, and corrosion of the electrode can be suppressed. In addition, it is easy to ensure high voltage resistance. Within these ranges, the lower limit can be 0.6 or more, or 0.8 or more.

[0141] It should be noted that the equivalent ratio of the base component to the first carboxylic acid compound refers to (the amount of OH that can be generated per molecule of the base component). - The total number of moles of the first carboxylic acid compound) / (the total number of carboxyl groups per molecule of the first carboxylic acid compound).

[0142] The equivalent ratio of the base component to the acid component (=base component / acid component) may be 0.1 to 10, 0.2 to 2, or 0.3 to 1.5. The equivalent ratio of the base component / acid component may be selected from the numerical range described as the equivalent ratio of the first carboxylic acid compound / base component.

[0143] The equivalent ratio of the base component to the acid component refers to the amount of OH generated per molecule of the base component. -The ratio is (total number of moles of) / (total number of acid groups per 1 molecule of acid components).

[0144] (Solvent)

[0145] Examples of the solvent contained in the liquid component include non-aqueous solvents. Examples of the non-aqueous solvent include sulfone compounds, lactone compounds, carbonate compounds, and alcohol compounds. The liquid component may include one non-aqueous solvent or a combination of two or more non-aqueous solvents.

[0146] Among the aprotic polar solvents, examples of sulfone compounds include cyclic sulfone compounds (sulfolane (SL) and the like), sulfoxide compounds (dimethyl sulfoxide and diethyl sulfoxide and the like), etc. Examples of lactone compounds include γ-butyrolactone (GBL) and γ-valerolactone and the like. Examples of carbonate compounds include chain carbonates (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and the like), cyclic carbonates (ethylene carbonate, propylene carbonate and fluoroethylene carbonate and the like), etc.

[0147] In the non-aqueous solvent, alcohol compounds include monohydric alcohols and polyhydric alcohols. Examples of the polyhydric alcohol include diol compounds (alkylene glycols (ethylene glycol (EG), propylene glycol, etc.), polyalkylene glycols (polyethylene glycol (PEG), polypropylene glycol, etc.), glycerol compounds (glycerol, polyglycerol, etc.), sugar alcohol compounds, or alkylene oxide adducts thereof (ethylene oxide adducts, polyethylene oxide adducts, etc.).

[0148] From the viewpoint of being suitable for improving the conductivity of the conductive polymer, the nonaqueous solvent preferably contains at least a diol compound. The nonaqueous solvent may contain a diol compound and a sulfone compound (cyclic sulfone compounds such as SL, etc.), and may also contain polyalkylene glycol (PEG, etc.).

[0149] (other)

[0150] The liquid component sometimes contains alkali metal ions (sodium ions, potassium ions, etc.). However, it is preferred that the concentration of the alkali metal ions in the liquid component is low. In addition, it is also preferred that the liquid component does not contain alkali metal ions. In this case, the alkali metal ions in the liquid component are below the detection limit.

[0151] The concentration of the alkali metal ions in the liquid component may be 100 ppm or less, or 50 ppm or less, on a mass basis.

[0152] (Capacitor element)

[0153] The capacitor element included in the electrolytic capacitor includes an anode body having a dielectric layer on the surface and a conductive polymer covering at least a portion of the dielectric layer. The conductive polymer constitutes at least a portion of the cathode body of the capacitor element. The cathode body may further include a cathode lead layer (cathode foil, etc.).

[0154] (Anode)

[0155] The anode body may include a valve metal, an alloy including a valve metal, a compound including a valve metal, etc. These materials may be used alone or in combination of two or more. As the valve metal, aluminum, tantalum, niobium, and titanium are preferred.

[0156] Anode foil is suitable as the anode body. The anode body preferably has a porous portion having pores at least in the surface layer. Anode bodies other than anode foil include porous sintered bodies or porous molded bodies containing particles of valve-acting metal.

[0157] The anode foil having a porous portion is obtained, for example, by roughening the surface of a substrate (foil-shaped or plate-shaped substrate, etc.) containing a valve-acting metal. The roughening can be performed by etching (for example, electrolytic etching or chemical etching) or the like.

[0158] (Dielectric layer)

[0159] The dielectric layer is formed by anodic oxidation of the valve action metal on the surface of the anode body. The anodic oxidation is performed, for example, by chemical conversion treatment, etc. The dielectric layer is formed, for example, to cover at least a portion of the surface of the anode body.

[0160] The dielectric layer includes an oxide of a valve metal. For example, when tantalum is used as the valve metal, the dielectric layer includes Ta2O5, and when aluminum is used as the valve metal, the dielectric layer includes Al2O3. It should be noted that the dielectric layer is not limited to this, as long as it functions as a dielectric.

[0161] The dielectric layer is usually formed on the surface of the anode body. When the dielectric layer is formed on the surface of the porous portion of the anode body, it is formed along the inner wall surface of the pores of the porous portion or the depressions (pits) on the surface of the anode body.

[0162] (Conductive polymer)

[0163] The conductive polymer, for example, includes a conjugated polymer and a dopant. The conductive polymer covers at least a portion of the dielectric layer. This method includes a case where the conductive polymer is in contact with at least a portion of the dielectric layer. In the case where the capacitor element includes an anode foil and a cathode foil, the conductive polymer may be between these foils. In this case, the conductive polymer may be impregnated into the diaphragm between the anode foil and the cathode foil. In addition to being in contact with at least a portion of the dielectric layer, the conductive polymer may also be in contact with at least a portion of the cathode foil. The conductive polymer may constitute a layer. Conductive polymers are sometimes also referred to as solid electrolytes. The conductive polymer constitutes at least a portion of the cathode body in the electrolytic capacitor. The conductive polymer may further contain additives as needed.

[0164] (Conjugated polymer)

[0165] As conjugated polymers, there can be mentioned well-known conjugated polymers used in electrolytic capacitors, such as π-conjugated polymers. As conjugated polymers, there can be mentioned polymers with basic skeletons such as polypyrrole, polythiophene, polyaniline, polyfuran, polyacetylene, polyphenylene, polyphenylene vinylene, polybenzone and polythiophene vinylene. The above polymers may contain at least one monomer unit constituting the basic skeleton. The above polymers also include homopolymers, copolymers of two or more monomers and their derivatives (substitutes with substituents, etc.). For example, polythiophene also includes poly (3,4-ethylenedioxythiophene) (PEDOT).

[0166] The conjugated polymer may be used alone or in combination of two or more.

[0167] The weight average molecular weight (Mw) of the conjugated polymer is not particularly limited, and is, for example, 1,000 or more and 1,000,000 or less.

[0168] In this specification, the weight average molecular weight (Mw) is a value calculated as polysaccharide measured by gel permeation chromatography (GPC). Note that GPC is generally measured using a polyhydroxymethacrylate gel column and a sodium nitrate aqueous solution as a mobile phase.

[0169] (Dopant)

[0170] As dopants, relatively small molecular anions, polymer anions, etc. can be cited. Examples of anions include sulfate ions, nitrate ions, phosphate ions, borate ions, organic sulfonate ions, carboxylate ions, etc. These compounds that generate anions are used as dopants. As dopants that generate sulfonate ions, for example, aromatic sulfonic acid compounds (p-toluenesulfonic acid and naphthalenesulfonic acid, etc.) can be cited. The aromatic sulfonic acid compound can have, for example, at least one selected from a carboxyl group and a hydroxyl group.

[0171] Examples of polymer anions include polyvinyl sulfonic acid, polystyrene sulfonic acid (PSS), polyallyl sulfonic acid, polypropylene sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamide-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, polyester sulfonic acid (aromatic polyester sulfonic acid, etc.), phenolsulfonic acid phenolic resin and polyacrylic acid. The polymer anion may be a polymer of a single monomer, a copolymer of two or more monomers, or a substituted product having a substituent. Among them, polyanions derived from polystyrene sulfonic acid are preferred.

[0172] However, these dopants are merely examples and are not limited thereto. A single dopant may be used alone or two or more dopants may be used in combination.

[0173] Conductive polymers can be formed, for example, by subjecting a precursor of a conjugated polymer to at least one of chemical polymerization and electrolytic polymerization on a dielectric layer in the presence of a dopant. Alternatively, conductive polymers (e.g., a layer of conductive polymers) can be formed by contacting a solution in which a conductive polymer is dissolved or a dispersion in which a conductive polymer is dispersed with a dielectric layer. The conductive polymers used in these solutions or dispersions can be obtained by polymerizing a precursor of a conjugated polymer in the presence of a dopant. As precursors of conjugated polymers, oligomers and prepolymers formed by connecting a plurality of molecular chains of a conjugated polymer, etc. can be cited. One precursor can be used, or two or more can be used in combination.

[0174] The Mw of the dopant is not particularly limited, and is, for example, 1,000 or more and 1,000,000 or less.

[0175] The amount of the dopant contained in the conductive polymer is, for example, 10 parts by mass or more and 1000 parts by mass or less, or 20 parts by mass or more and 500 parts by mass or less, relative to 100 parts by mass of the conjugated polymer.

[0176] (Cathode lead layer)

[0177] The cathode lead layer, for example, comprises a first layer covering at least a portion of the conductive polymer. The cathode lead layer may also comprise a first layer and a second layer covering the first layer. As the first layer, for example, a layer containing conductive particles, a metal foil (cathode foil), etc. may be cited. As the conductive particles, for example, at least one selected from conductive carbon and metal powder may be cited. For example, the cathode lead layer may also be composed of a layer containing conductive carbon (graphite, etc.) as the first layer (also referred to as a carbon layer) and a layer containing metal powder or a metal foil as the second layer. When a metal foil is used as the first layer, the cathode lead layer may also be composed of the metal foil. The cathode lead layer may be formed by a known method according to the layer composition.

[0178] The layer containing metal powder as the second layer can be formed, for example, by laminating a composition containing metal powder on the surface of the first layer. As such a second layer, for example, a metal paste layer (silver paste layer, etc.) formed using a composition containing metal powder such as silver particles and a resin (binder resin) can be cited. As the resin, a thermosetting resin such as an imide resin and an epoxy resin can be used, and a thermoplastic resin can also be used.

[0179] When a metal foil is used as the first layer, the type of metal is not particularly limited, and preferably a valve metal such as aluminum, tantalum, niobium, or an alloy containing a valve metal is used. The surface of the metal foil may be roughened as required. A chemical conversion film may be provided on the surface of the metal foil, or a film of a metal (heterogeneous metal) or a non-metallic film different from the metal constituting the metal foil may be provided. Examples of heterogeneous metals and non-metals include metals such as titanium, and non-metals such as carbon (conductive carbon, etc.).

[0180] The coating of the above-mentioned dissimilar metal or non-metal (for example, conductive carbon) may be used as the first layer, and the above-mentioned metal foil may be used as the second layer.

[0181] (Diaphragm)

[0182] A separator may be arranged between the cathode body (cathode foil, etc.) and the anode body (anode foil, etc.). The separator is not particularly limited, and for example, nonwoven fabrics containing fibers of cellulose, polyethylene terephthalate, vinylon, polyamide (for example, aliphatic polyamide, aromatic polyamide such as aramid) and the like may be used.

[0183] In the case where the capacitor element includes a diaphragm, the conductive polymer may be impregnated into the diaphragm. The conductive polymer may be interposed between the anode body (anode foil, etc.) and the cathode body (cathode foil, etc.), and may be in contact with at least a portion of the dielectric layer and at least a portion of the cathode body. In the present invention, the high conductivity of the conductive polymer can be maintained by combining the conductive polymer with the liquid component containing the first carboxylic acid compound, and therefore, in these embodiments, the reduction of ESR can also be suppressed.

[0184] (other)

[0185] The electrolytic capacitor may be a wound type, a chip type or a stacked type. The electrolytic capacitor has at least one capacitor element. The electrolytic capacitor may have multiple capacitor elements. For example, the electrolytic capacitor may have a stack of two or more capacitor elements, or may have two or more wound capacitor elements. The composition or number of capacitor elements may be selected according to the type or purpose of the electrolytic capacitor.

[0186] In the capacitor element, one end of the cathode lead is electrically connected to the cathode lead layer. One end of the anode lead is electrically connected to the anode body. The other end of the anode lead and the other end of the cathode lead are respectively led out from the outer body or the shell. The other end of each lead exposed from the outer body or the shell is used for welding connection with a substrate on which the electrolytic capacitor is to be mounted. As each lead, a lead wire or a lead frame can be used.

[0187] Figure 1 is a schematic cross-sectional view of an electrolytic capacitor according to this embodiment, Figure 2 Schematic diagram showing a portion of the capacitor element of the electrolytic capacitor. However, the electrolytic capacitor of the present invention is not limited to the following embodiments. In addition, the constituent elements of the following embodiments may be arbitrarily combined with at least one of the above (1) to (13) of the solid electrolytic capacitor of the present invention, or may be arbitrarily combined with at least one of the above (1) to (13) and the constituent elements described above.

[0188] The electrolytic capacitor includes, for example, a capacitor element 10, a bottomed case 101 that accommodates the capacitor element 10 and a liquid component (not shown), a sealing member 102 that blocks an opening of the bottomed case 101, a seat plate 103 that covers the sealing member 102, leads 104A and 104B that are led out from the sealing member 102 and pass through the seat plate 103, and lead tabs 105A and 105B that connect the leads to electrodes of the capacitor element 10. The vicinity of the opening end of the bottomed case 101 is drawn inward, and the opening end is curled so as to be crimped to the sealing member 102.

[0189] The capacitor element 10 is, for example, Figure 2 The winding body shown. The winding body includes an anode foil 11 connected to a lead connector 105A, a cathode foil 12 connected to a lead connector 105B, and a separator 13. The anode foil 11 and the cathode foil 12 are wound with the separator 13 interposed therebetween. The outermost periphery of the winding body is fixed by a stopper tape 14. It should be noted that Figure 2 The partially unfolded state is shown before the outermost circumference of the wound body is fixed.

[0190] In the capacitor element 10, a dielectric layer (not shown) is formed on at least a portion of the surface of the anode foil 11. The separator 13 and the conductive polymer (not shown) are interposed between the anode foil 11 and the cathode foil 12. The conductive polymer is in contact with at least a portion of the dielectric layer. In addition, the conductive polymer is in contact with at least a portion of the cathode foil 12. In addition, the conductive polymer and the separator are impregnated with a liquid component.

[0191] [Example]

[0192] Hereinafter, the electrolytic capacitor of the present invention will be specifically described based on Examples and Comparative Examples, but the electrolytic capacitor of the present invention is not limited to the following Examples.

[0193] 《Manufacturing Example 1》

[0194] The first carboxylic acid compound a1 is produced according to the following steps.

[0195] Under a nitrogen atmosphere, sodium hydride (48 mmol) was added to the suspension obtained by suspending ethylene glycol (24 mmol) in xylene (100 g) and stirred. To the obtained mixture was added n-octyl succinic anhydride (48 mmol) dropwise, and the mixture was reacted for 5 hours. After the reaction was completed, an aqueous sulfuric acid solution (5% concentration by mass, 100 g) was added to the obtained mixture, transferred to a separatory funnel, and fully shaken and mixed, and the phases were separated into an aqueous phase and an organic phase. The aqueous phase was removed, and the organic phase was washed with pure water. The solvent was removed from the washed organic phase using an evaporator. The structure of the obtained first carboxylic acid compound a1 was determined by liquid chromatography-mass spectrometry (LC / MS) (ion source: ESI - ) analysis to confirm.

[0196] 《Manufacturing Example 2》

[0197] A first carboxylic acid compound a2 was produced in the same manner as in Production Example 1 except that tripropylene glycol (24 mmol) was used instead of ethylene glycol.

[0198] 《Manufacturing Example 3》

[0199] A first carboxylic acid compound a3 was produced by the same procedure as in Production Example 1 except that ethylenediamine (24 mmol) was used instead of ethylene glycol and triethylamine (48 mmol) was used instead of sodium hydride.

[0200] 《Manufacturing Example 4》

[0201] A first carboxylic acid compound a4 was produced in the same manner as in Production Example 1 except that 1,2-cyclohexanedicarboxylic anhydride (48 mmol) was used instead of n-octylsuccinic anhydride.

[0202] 《Manufacturing Example 5》

[0203] A first carboxylic acid compound a5 was produced in the same manner as in Production Example 1 except that 2-octenylsuccinic anhydride (48 mmol) was used instead of n-octylsuccinic anhydride.

[0204] 《Manufacturing Example 6》

[0205] A first carboxylic acid compound a6 was produced in the same manner as in Production Example 1 except that n-butylsuccinic anhydride (48 mmol) was used instead of n-octylsuccinic anhydride.

[0206] 《Manufacturing Example 7》

[0207] A first carboxylic acid compound a7 was prepared in the same manner as in Preparation Example 1 except that n-dodecylsuccinic anhydride (48 mmol) was used instead of n-octylsuccinic anhydride.

[0208] 《Manufacturing Example 8》

[0209] A first carboxylic acid compound a8 was prepared in the same manner as in Preparation Example 1 except that n-dodecenylsuccinic anhydride (48 mmol) was used instead of n-octylsuccinic anhydride.

[0210] 《Manufacturing Example 9》

[0211] A first carboxylic acid compound a9 was produced in the same manner as in Production Example 1 except that 2,2-dimethylsuccinic anhydride (48 mmol) was used instead of n-octylsuccinic anhydride.

[0212] 《Manufacturing Example 10》

[0213] A first carboxylic acid compound a10 was produced in the same manner as in Production Example 1 except that phenylsuccinic anhydride (48 mmol) was used instead of n-octylsuccinic anhydride.

[0214] 《Manufacturing Example 11》

[0215] A first carboxylic acid compound a11 was produced in the same manner as in Production Example 5 except that 1,4-butanediol (24 mmol) was used instead of ethylene glycol.

[0216] 《Manufacturing Example 12》

[0217] A first carboxylic acid compound a12 was produced in the same manner as in Production Example 5 except that 1,9-nonanediol (24 mmol) was used instead of ethylene glycol.

[0218] 《Manufacturing Example 13》

[0219] A first carboxylic acid compound a13 was produced in the same manner as in Production Example 5 except that triethylene glycol (24 mmol) was used instead of ethylene glycol.

[0220] 《Manufacturing Example 14》

[0221] A first carboxylic acid compound a14 was produced in the same manner as in Production Example 5 except that 2-butyl-2-ethyl-1,3-propanediol (24 mmol) was used instead of ethylene glycol.

[0222] 《Manufacturing Example 15》

[0223] Trimethylolpropane (24 mmol) was used instead of ethylene glycol, and 72 mmol of 2-octenylsuccinic anhydride was used. Except for these, the same procedure as in Production Example 5 was followed to produce the first carboxylic acid compound a15.

[0224] 《Manufacturing Example 16》

[0225] The first carboxylic acid compound a16 was prepared by the same procedure as in Preparation Example 5 except that piperazine (24 mmol) was used instead of ethylene glycol and triethylamine (48 mmol) was used instead of sodium hydride.

[0226] 《Manufacturing Example 17》

[0227] A first carboxylic acid compound a17 was prepared in the same manner as in Preparation Example 5 except that N,N′-diisopropylethylenediamine (24 mmol) was used instead of ethylene glycol and triethylamine (48 mmol) was used instead of sodium hydride.

[0228] 《Manufacturing Example 18》

[0229] A first carboxylic acid compound a18 was produced in the same manner as in Production Example 1 except that 5-norbornene-2,3-dicarboxylic acid (48 mmol) was used instead of n-octylsuccinic anhydride.

[0230] 《Manufacturing Example 19》

[0231] A first carboxylic acid compound a19 was produced in the same manner as in Production Example 1 except that phthalic acid (48 mmol) was used instead of n-octylsuccinic anhydride.

[0232] 《Examples 1 to 28 and Comparative Examples 1 to 11》

[0233] A wound electrolytic capacitor (rated voltage 25 V, rated capacitance 330 μF) was produced and evaluated according to the following procedure.

[0234] (Preparation of anode body)

[0235] An aluminum foil having a thickness of 100 μm was etched to roughen the surface of the aluminum foil. Then, a dielectric layer was formed on the surface of the aluminum foil by chemical conversion treatment. The chemical conversion treatment was performed by immersing the aluminum foil in an ammonium adipate solution and applying a voltage thereto. Then, the aluminum foil was cut into a size of 8 mm in length and 120 mm in width to prepare an anode body.

[0236] (Preparation of cathode body)

[0237] An aluminum foil having a thickness of 50 μm was subjected to etching treatment to roughen the surface of the aluminum foil, and then the aluminum foil was cut into a size of 8 mm in length×120 mm in width to prepare a cathode body.

[0238] (Production of wound body)

[0239] The anode lead connector and the cathode lead connector are connected to the anode body and the cathode body, and the anode body and the cathode body are wound into the lead connector while being wound through the separator. The anode lead and the cathode lead are respectively connected to the ends of each lead connector protruding from the wound body. Then, the prepared wound body is subjected to chemical conversion treatment again, and a dielectric layer is formed at the cut end of the anode body. Next, the end of the outer surface of the wound body is fixed with a winding stopper to prepare the wound body.

[0240] (Preparation of polymer dispersion containing conductive polymer)

[0241] 3,4-ethylenedioxythiophene and poly(4-styrenesulfonic acid) (PSS, Mw 100,000) as a polymer dopant are dissolved in ion exchange water to prepare a mixed solution. While stirring the mixed solution, an oxidant (iron (III) sulfate and ammonium persulfate) dissolved in ion exchange water is added to carry out a polymerization reaction. After the reaction, the obtained reaction solution is dialyzed to remove unreacted monomers and excess oxidant, and a polymer dispersion containing poly(3,4-ethylenedioxythiophene) (PEDOT / PSS) doped with PSS as a conductive polymer is obtained. It should be noted that the Mw of the polymer dopant is the value measured under the above conditions.

[0242] (Coating of dielectric layer with conductive polymer)

[0243] In a reduced pressure atmosphere (40 kPa), the wound body was immersed in a polymer dispersion stored in a predetermined container for 5 minutes, and then the wound body was lifted from the polymer dispersion. Next, the wound body impregnated with the polymer dispersion was dried in a drying oven at 150°C for 20 minutes, and at least a portion of the dielectric layer was coated with a conductive polymer. In this way, a capacitor element was formed. However, in Comparative Examples 8 to 10, capacitor elements were formed without performing this step of coating the dielectric layer with a conductive polymer.

[0244] (Impermeation of liquid components)

[0245] The solvent of the liquid component is a mixture obtained by mixing EG, PEG (number average molecular weight Mn: 300) and SL in a volume ratio of EG:PEG:SL=1:1:1. The liquid component is prepared by dissolving a solute in the mixture. The solute uses an acid component shown in Table 1 and Table 2 and a base component shown in Table 2 such as triethylamine (TEA). In the examples and comparative examples 8 to 9, the first carboxylic acid compound produced in Preparation Examples 1 to 19 is used. The number of the first site in each first carboxylic acid compound is also recorded in Table 1. The amount of each component added to the solvent is adjusted so that the concentration of the acid component and the base component in the liquid component becomes the value shown in Table 2. The equivalent ratio of the acid component / base component is also recorded in Table 2.

[0246] (Assembly of electrolytic capacitors)

[0247] The capacitor element was immersed in the liquid component and then left in a reduced pressure atmosphere (40 kPa) for 5 minutes to allow the liquid component to permeate into the capacitor element.

[0248] The capacitor element impregnated with the liquid component is housed in a bottomed shell in such a manner that the lead wire is located on the open side of the bottomed shell. A sealing member (an elastic material containing butyl rubber as a rubber component) formed in such a manner that the lead wire passes through is arranged above the capacitor element. Then, a deep drawing process is performed near the open end of the bottomed shell, and the open end is further curled to make it fit closely with the sealing member. In this way, the capacitor element and the liquid component are sealed in the bottomed shell. By arranging a seat plate in the curled portion, the following is completed. Figure 1 The electrolytic capacitors shown in the figure. A total of 40 electrolytic capacitors were produced in each example. The produced electrolytic capacitors were aged at 130° C. for 2 hours while applying a rated voltage.

[0249] [evaluate]

[0250] The electrolytic capacitors produced as described above were evaluated as follows.

[0251] (1) Change in electrostatic capacitance (Δcap) and change in ESR (ΔESR)

[0252] For 20 electrolytic capacitors after aging, the electrostatic capacitance at a frequency of 120 Hz and the ESR value at a frequency of 100 kHz were measured using an LCR meter at 20°C, and the average values ​​(initial electrostatic capacitance value: X0 (F), initial ESR value: Y0 (Ω)) were calculated.

[0253] After the measurement of X0 and Y0, a high temperature load test (accelerated test) is performed. That is, the rated voltage is applied to the electrolytic capacitor at a temperature of 145°C for 1000 hours. For the electrolytic capacitor after the accelerated test, the average electrostatic capacitance value (X1 (F)) and ESR value (Y1 (Ω)) after the accelerated test are calculated according to the initial electrostatic capacitance value and initial ESR value.

[0254] Using the obtained X0 and X1, and Y0 and Y1, the initial capacity change (Δcap) and the ESR change (ΔESR) were calculated by the following equations.

[0255] Δcap=X1 / X0

[0256] ΔESR=Y1 / Y0

[0257] (2) Leakage current change (ΔLC)

[0258] A 1 kΩ resistor was connected in series to the 20 electrolytic capacitors remaining after the aging treatment, and the leakage current was measured after a rated voltage of 25 V was applied for 1 minute using a DC power supply. The average value (Z0: initial leakage current (A)) was calculated.

[0259] The 20 electrolytic capacitors for which the initial leakage current Z0 was measured were subjected to an accelerated test at 145°C without applying voltage. The leakage current (A) of the electrolytic capacitors after the accelerated test was measured in the same manner as the initial leakage current, and the average value of the 20 electrolytic capacitors was calculated (Z1: leakage current (A) after the accelerated test).

[0260] ΔLC=Z1 / Z0

[0261] The acid components used in the liquid component are shown in Table 1. The evaluation results of each electrolytic capacitor are shown in Table 2. In Table 1, a1 to a19 are first carboxylic acid compounds, and b1 to b3 are acid components other than the first carboxylic acid compound (specifically, second carboxylic acid compounds). In Table 2, A1 to A28 are examples, and B1 to B11 are comparative examples.

[0262] [Table 1]

[0263]

[0264] [Table 2]

[0265]

[0266] As shown in Table 2, in the electrolytic capacitors not containing the conductive polymer, the leakage current after the accelerated test was suppressed to a small level, but the electrostatic capacitance was greatly reduced (B8 to B11). In addition, ΔESR did not change significantly when the liquid component containing the first carboxylic acid compound was used and when the liquid component containing an acid component other than the first carboxylic acid compound was used.

[0267] In contrast, in the electrolytic capacitor containing a conductive polymer, a large difference can be seen in ΔESR in particular when a liquid component containing a first carboxylic acid compound is used and a liquid component containing an acid component other than the first carboxylic acid compound (second carboxylic acid compound) is used. More specifically, in B1 to B6 using a liquid component containing a second carboxylic acid compound, ΔESR is 3.10 to 172.09. In particular, in B2 to B6 using aliphatic dicarboxylic acids, ΔESR is large, 9.34 to 172.09. In contrast to these results, in A1 to A28 using a liquid component containing a first carboxylic acid compound in an electrolytic capacitor containing a conductive polymer, ΔESR is less than 2.25, which is quite small compared to B1 to B6, and the change in ESR caused by the accelerated test is suppressed to be small. The first carboxylic acid compound used in A1 to A5 and A7 to A25 can be said to have a portion of the main chain of the entire compound as an aliphatic chain, but can significantly reduce ΔESR compared to B2 to B6 using an aliphatic dicarboxylic acid. In this way, it can be said that the behavior of ΔESR caused by the liquid component containing the first carboxylic acid compound is very different when the electrolytic capacitor contains a conductive polymer and when it does not contain a conductive polymer. In addition, in A1 to A28, the leakage current after the accelerated test is also suppressed to a small level, and a larger electrostatic capacitance than B1 to B6 can be obtained after the accelerated test. In this way, the electrolytic capacitor of the embodiment can also ensure excellent capacitor performance after the accelerated test and has excellent reliability.

[0268] The preferred embodiments of the present invention are described, but such disclosure is not interpreted restrictively. By reading the above disclosure, various deformations and changes are undoubtedly obvious to those skilled in the art of the technical field to which the present invention belongs. Therefore, the scope of the attached claims should be interpreted as including all deformations and changes without departing from the true spirit and scope of the present invention.

[0269] Industrial Applicability

[0270] The electrolytic capacitor of the present invention can be used as a hybrid electrolytic capacitor. In the electrolytic capacitor, the time-dependent change of ESR can be reduced. In addition, in the electrolytic capacitor, the time-dependent increase of leakage current can be suppressed, and a high withstand voltage can be ensured. Therefore, the electrolytic capacitor of the present invention is particularly suitable for various uses requiring high reliability or long life. However, the uses of electrolytic capacitors are not limited to these.

[0271] Description of Reference Numerals

[0272] 100: Electrolytic capacitor

[0273] 101: Shell with bottom

[0274] 102: Sealing components

[0275] 103: Seat plate

[0276] 104A, 104B: Lead wire

[0277] 105A, 105B: Lead connector

[0278] 10: Capacitor components

[0279] 11: Anode foil

[0280] 12: Cathode foil

[0281] 13: Diaphragm

[0282] 14: Stop tape

Claims

1. An electrolytic capacitor comprising a capacitor element and a liquid component, The capacitor element includes an anode body having a dielectric layer on its surface and a conductive polymer covering at least a portion of the dielectric layer. The liquid component comprises an acid component and a solvent, The acid component includes a first carboxylic acid compound having a plurality of first sites, The plurality of first parts each independently have: a first carboxyl group comprising a first carbonyl group; A second carbonyl group; and A first linking group that links the first carbonyl group to the second carbonyl group.

2. The electrolytic capacitor according to claim 1, wherein: The first carboxylic acid compound has a second connecting group, The second linking group links the second carbonyl groups of the plurality of first sites to each other.

3. The electrolytic capacitor according to claim 2, wherein: The second linking group has an oxygen atom or an amino group bonded to the second carbonyl group.

4. The electrolytic capacitor according to any one of claims 1 to 3, wherein The first linking groups in at least two of the first sites have the same structure.

5. The electrolytic capacitor according to any one of claims 1 to 4, wherein In the first linking groups of at least two of the first sites, the number of carbon atoms of the main chain connecting the first carbon atom of the first carbonyl group and the second carbonyl group is 1 or more and 4 or less.

6. The electrolytic capacitor according to any one of claims 1 to 5, wherein The first linking groups of at least two of the first sites include a non-aromatic cyclic divalent group or an aromatic divalent group.

7. The electrolytic capacitor according to any one of claims 1 to 5, wherein In the first linking groups of at least two of the first sites, a main chain connecting the first carbon atom of the first carbonyl group and the second carbon atom of the second carbonyl group is an aliphatic divalent group.

8. The electrolytic capacitor according to claim 7, wherein: The aliphatic divalent group has a first substituent, The aliphatic divalent group has a monovalent aliphatic hydrocarbon group having 6 or more carbon atoms as at least one of the first substituents.

9. The electrolytic capacitor according to claim 8, wherein: The aliphatic divalent group has the monovalent aliphatic hydrocarbon group at the α position to the first carbonyl group.

10. The electrolytic capacitor according to any one of claims 1 to 9, wherein The acid component further includes a second carboxylic acid compound different from the first carboxylic acid compound.

11. The electrolytic capacitor according to any one of claims 1 to 10, wherein: The first carboxylic acid compound accounts for 20% by mass or more of the acid component.

12. The electrolytic capacitor according to any one of claims 1 to 11, wherein: The liquid component further comprises an alkali component.

13. The electrolytic capacitor according to claim 12, wherein: The equivalent ratio of the first carboxylic acid compound to the base component is 0.4 or more and 10 or less.

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