Conductive composite, conductive polymer dispersion, conductive laminate and capacitor

Abstract

To provide a conductive polymer dispersion having a reduced increase in viscosity during storage and good conductivity after drying and curing, a conductive composite capable of forming the conductive polymer dispersion and a conductive laminate and a capacitor containing a cured product of the conductive polymer dispersion.SOLUTION: There is provided a conductive composite containing a π-conjugated conductive polymer and a polyanion, wherein when analyzing a polyanion solution in which the polyanion is dissolved independently of the π-conjugated conductive polymer in an aqueous solvent by a gel permeation chromatography system, of the detection signal intensity corresponding to the polyanion content, the ratio represented by PSSA2 / PSSA1 of the area PSSA1 of the main peak on the high molecular weight side and the area PSSA2 of the sub-peak on the low molecular weight side is 2.5% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a conductive composite containing a π-conjugated conductive polymer and a polyanion, a conductive polymer dispersion, a conductive laminate, and a capacitor.

Background Art

[0002] A π-conjugated conductive polymer whose main chain is composed of a π-conjugated system forms a conductive composite by doping with a polyanion having an anion group, and exhibits dispersibility in water. A method for manufacturing a capacitor is disclosed in which a paint made of a conductive polymer dispersion containing a conductive composite is applied to a dielectric layer provided on the surface of an anode made of valve metal, dried to form a solid electrolyte layer, and a cathode is disposed opposite thereto (for example, Patent Document 1). According to this disclosure, the performance of the capacitor is improved by including a specific unsaturated aliphatic alcohol compound in the paint.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The conductive polymer dispersion used for manufacturing a capacitor is required to have a low viscosity in order to penetrate into the porous structure of the dielectric layer. Furthermore, the solid electrolyte layer formed by drying the infiltrated conductive polymer dispersion is also required to have high conductivity. However, there has been a problem that the viscosity of conventional conductive polymer dispersions increases during storage. The increase in viscosity has been a problem not only in the manufacture of capacitors but also in the manufacture of conductive laminates formed by applying a conductive polymer dispersion to a substrate to form a conductive layer.

[0005] The present invention provides a conductive polymer dispersion liquid with reduced viscosity increase during storage and good conductivity after drying and curing, a conductive composite capable of forming the conductive polymer dispersion liquid, and a conductive laminate and a capacitor including a cured product of the conductive polymer dispersion liquid. [Means for Solving the Problems]

[0006] [1] A conductive composite including a π-conjugated conductive polymer and a polyanion, wherein for an aqueous polyanion solution in which the polyanion is dissolved independently of the π-conjugated conductive polymer in an aqueous solvent, when analyzed by a gel permeation chromatography system, among the detection signal intensities corresponding to the content of the polyanion, the ratio represented by PSSA2 / PSSA1 of the area PSSA1 of the main peak on the high molecular weight side and the area PSSA2 of the sub-peak on the low molecular weight side is 2.5% or less. [2] The analysis by the gel permeation chromatography system measures the weight average molecular weight of the polyanion using pullulan with a known weight average molecular weight as a standard, and the weight average molecular weight of the main peak is 90,000 to 200,000. The conductive composite according to [1]. [3] The weight average molecular weight of the sub-peak is 500 to 2,000. The conductive composite according to [1] or [2]. [4] The π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene). The conductive composite according to any one of [1] to [3]. [5] The polyanion is polystyrene sulfonic acid. The conductive composite according to any one of [1] to [4]. [6] A conductive polymer dispersion liquid including the conductive composite according to any one of [1] to [5] and water. [7] The conductive polymer dispersion liquid according to [6], further including an anionic surfactant different from the polyanion. [8] The anionic surfactant is linear alkylbenzene sulfonic acid or a salt thereof. The conductive polymer dispersion liquid according to [7]. [9] A conductive laminate comprising a base material and a conductive layer formed on at least a part of the surface of the base material, wherein the conductive layer contains a cured product of the conductive polymer dispersion liquid according to any one of [6] to [8].

[10] A capacitor comprising an anode made of a porous body of valve metal, a dielectric layer made of an oxide of the valve metal, a cathode made of a conductive material provided on the side of the dielectric layer opposite to the anode, and a solid electrolyte layer formed between the dielectric layer and the cathode, wherein the solid electrolyte layer contains a cured product of the conductive polymer dispersion liquid according to any one of [6] to [8].

Advantages of the Invention

[0007] In the conductive polymer dispersion liquid containing the conductive composite of the present invention, the increase in viscosity during storage is suppressed and the storage stability is high, so it is suitable for the production of conductive laminates and capacitors. Also, the conductivity of the cured product of the conductive polymer dispersion liquid of the present invention is good, and the conductivity of the conductive layer of the conductive laminate containing the cured product and the solid electrolyte layer of the capacitor containing the cured product is also excellent.

[0008] The present invention is considered to contribute to SDGs Goal 12, "Responsibility to Produce and Responsibility to Use".

[0009] In this specification and the claims, the lower limit value and the upper limit value of the numerical range indicated by "~" are included in the numerical range.

Brief Description of the Drawings

[0010]

Figure 1

Embodiments for Carrying Out the Invention

[0011] ≪Conductive Composite≫ The first aspect of the present invention is a conductive composite comprising a π-conjugated conductive polymer and a polyanion. In water, the π-conjugated conductive polymer is positively charged and the polyanion is negatively charged, so it is considered that the two mainly form a composite by electrostatic interaction. Usually, the conductive composite is formed by polymerizing the monomers of the π-conjugated conductive polymer in water containing the polyanion, and the formed π-conjugated conductive polymer is naturally doped with the polyanion. Therefore, the weight average molecular weight of the polyanion constituting the conductive composite is equal to the weight average molecular weight of the polyanion pre-formulated in the polymerization reaction solution of the monomer.

[0012] Assume an aqueous polyanion solution in which the polyanion constituting the conductive composite of this aspect is separated from the π-conjugated conductive polymer by any method and dissolved in water as an independent polymer. When the aqueous polyanion solution is analyzed by a gel permeation chromatography system (GPC), it is eluted from the gel permeation column in order from the polyanion with a high Mw at the retention time corresponding to the weight average molecular weight (mass average molecular weight, Mw) of the polyanion. The amount of polyanion contained in the solution flowing out of the column at each retention time is observed as the detection signal intensity of the detector. Examples of the detector used here include a differential refractive index detector (RI detector), an ultraviolet detector, a light scattering detector, an evaporative light scattering detector, a viscosity detector, an electrical conductivity detector, and the like. The differential refractive index detector is preferred because of its high reliability and simple device configuration. In GPC analysis, it is common to create a chart with the retention time on the horizontal axis and the detection signal intensity on the vertical axis. In this chart, one or more peaks that can approximate a normal distribution reflecting the Mw of the polyanion contained in the aqueous polyanion solution are observed.

[0013] Regarding the conductive composite of this aspect, usually one or two peaks are observed in the GPC chart of the polyanion aqueous solution. Among these peaks, the ratio represented by PSSA2 / PSSA1 of the area PSSA1 of the main peak on the high molecular weight side and the area PSSA2 of the sub-peak on the low molecular weight side is preferably lower, and in the order of 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, 0.5% or less, 0% (the sub-peak is below the detection limit) is more preferable. That is, it is more preferable that the Mw of the polyanion constituting the conductive composite of this aspect shows a distribution (generally a normal distribution) observed as a single peak in GPC analysis. Here, the molecular weight distribution of the main peak is preferably 1.8 to 2.5, and the molecular weight distribution of the sub-peak is preferably 1.1 to 1.5. The lower the ratio, the higher the storage stability of the conductive polymer dispersion containing the conductive composite of this aspect.

[0014] When performing GPC analysis of the polyanion aqueous solution, the Mw of the polyanion is determined in terms of pullulan conversion. That is, pullulan with a known Mw is used as a standard sample to create a calibration curve, and based on this, the Mw of the polyanion is measured.

[0015] In the GPC analysis of the polyanion aqueous solution regarding the conductive composite of this aspect, the Mw of the main peak on the high molecular weight side of the polyanion is preferably 90,000 to 200,000, more preferably 120,000 to 200,000, and even more preferably 140,000 to 200,000. When within the above range, the storage stability of the conductive polymer dispersion containing the conductive composite of this aspect is further enhanced.

[0016] In the GPC analysis of the polyanion aqueous solution regarding the conductive composite of this aspect, the Mw of the sub-peak on the low molecular weight side of the polyanion is preferably 500 to 2,000. When within the above range, the storage stability of the conductive polymer dispersion containing the conductive composite of this aspect is further enhanced.

[0017] As the type of the column for gel permeation chromatography used in the above GPC analysis, any column having a resolution capable of observing the above main peak and sub-peak as individual peaks may be used. The solvent of the polyanion aqueous solution to be subjected to the above GPC analysis is preferably water. The content of the polyanion with respect to the total mass of the polyanion aqueous solution to be subjected to the above GPC analysis can be, for example, 9 to 11% by mass.

[0018] <Conductive composite> The conductive composite of this embodiment contains a π-conjugated conductive polymer and a polyanion. The polyanion in the conductive composite dopes the π-conjugated conductive polymer to form a conductive composite having conductivity. In the polyanion, only some of the anion groups are doped into the π-conjugated conductive polymer, and there are surplus anion groups that do not participate in the doping. Since the surplus anion groups are hydrophilic groups, the conductive composite has water dispersibility. When the number of all anion groups possessed by the polyanion is 100 mol%, the surplus anion groups are preferably 30 mol% or more and 90 mol% or less, and more preferably 45 mol% or more and 75 mol% or less.

[0019] (π-conjugated conductive polymer) The π-conjugated conductive polymer may be an organic polymer whose main chain is composed of a π-conjugated system. For example, polypyrrole-based conductive polymers, polythiophene-based conductive polymers, polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylene vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene vinylene-based conductive polymers, and copolymers thereof can be mentioned. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferable, and from the viewpoint of transparency, polythiophene-based conductive polymers are more preferable.

[0020] Examples of polythiophene-based conductive polymers include polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3-chlorothiophene), poly(3-iodothiophene), poly(3-cyanothiophene), poly(3-phenylthiophene), poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene), poly(3-hydroxythiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-decyloxythiophene), poly(3-dodecyloxythiophene), poly(3-octadecyloxythiophene), poly(3,4-dihydroxythiophene), poly(3,4-dimethoxythiophene), poly(3,4-diethoxythiophene), poly(3,4-dipropoxythiophene), poly(3,4-dibutoxythiophene), poly(3,4-dihexyloxythiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-didodecyloxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene), poly(3-methyl-4-methoxythiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3-methyl-4-carboxybutylthiophene). Examples of polypyrrole-based conductive polymers include polypyrrole, poly(N-methylpyrrole), poly(3-methylpyrrole), poly(3-ethylpyrrole), poly(3-n-propylpyrrole), poly(3-butylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly(3-carboxypyrrole), poly(3-methyl-4-carboxypyrrole), poly(3-methyl-4-carboxyethylpyrrole), poly(3-methyl-4-carboxybutylpyrrole), poly(3-hydroxypyrrole), poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-butoxypyrrole), poly(3-hexyloxypyrrole), and poly(3-methyl-4-hexyloxypyrrole). Examples of polyaniline-based conductive polymers include polyaniline, poly(2-methylaniline), poly(3-isobutylaniline), poly(2-anilinesulfonic acid), and poly(3-anilinesulfonic acid). Among these π-conjugated conductive polymers, poly(3,4-ethylenedioxythiophene) is particularly preferred because of its excellent conductivity, transparency, and heat resistance. The π-conjugated conductive polymer contained in the conductive composite may be one type or two or more types.

[0021] (Polyanion) A polyanion is a polymer having two or more monomer units having an anion group in the molecule. The anion group of this polyanion functions as a dopant for the π-conjugated conductive polymer and improves the conductivity of the π-conjugated conductive polymer. The anion group of the polyanion is preferably a sulfo group or a carboxy group. Specific examples of such polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylate esters having a sulfo group, polymethacrylate esters having a sulfo group (e.g., poly(4-sulfobutyl methacrylate), polysulfoethyl methacrylate, polymethacryloyloxybenzene sulfonic acid), polymers having a sulfo group such as poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polymers having a carboxy group such as polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropane carboxylic acid), polyisoprene carboxylic acid. The polyanion may be a homopolymer obtained by polymerizing a single monomer or a copolymer obtained by polymerizing two or more monomers. Among these polyanions, polymers having a sulfo group are preferable and polystyrene sulfonic acid is more preferable because the conductivity can be made higher.

[0022] The content ratio of the polyanion contained in the conductive composite of this embodiment is preferably in the range of, for example, 1 part by mass or more and 1000 parts by mass or less, more preferably 10 parts by mass or more and 700 parts by mass or less, and even more preferably 100 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the π-conjugated conductive polymer. If the content ratio of the polyanion is at least the lower limit value, the doping effect on the π-conjugated conductive polymer tends to be stronger and the conductivity becomes higher. On the other hand, if the content of the polyanion is at most the upper limit value, the content ratio of the π-conjugated conductive polymer becomes sufficient, so that sufficient conductivity can be ensured.

[0023] ≪Conductive Polymer Dispersion Liquid≫ The second aspect of the present invention is a conductive polymer dispersion liquid containing the conductive composite of the first aspect and water.

[0024] The content ratio of the polyanion contained in the conductive polymer dispersion of this aspect is preferably in the range of, for example, 1 part by mass or more and 1000 parts by mass or less, more preferably 10 parts by mass or more and 700 parts by mass or less, and even more preferably 100 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the π-conjugated conductive polymer. If the content ratio of the polyanion is equal to or higher than the lower limit value, the doping effect on the π-conjugated conductive polymer tends to be stronger, and the conductivity becomes higher. On the other hand, if the content of the polyanion is equal to or lower than the upper limit value, the π-conjugated conductive polymer can be sufficiently contained, so that sufficient conductivity can be ensured.

[0025] The total content of the π-conjugated conductive polymer and the polyanion with respect to the total mass of the conductive polymer dispersion of this aspect is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.5% by mass or more and 2.5% by mass or less. Within the above preferable range, the dispersibility of the conductive composite is enhanced and the storage stability is improved. In addition, the ESR of the capacitor having the solid electrolyte layer formed from the conductive polymer dispersion can be further reduced.

[0026] (Dispersion medium) Since the conductive composite is hydrophilic, the dispersion medium contained in the conductive polymer dispersion is preferably an aqueous dispersion medium containing water. In addition, it may contain a dispersion medium other than water. The dispersion medium other than water is not particularly limited as long as it does not significantly impair the dispersibility of the conductive composite. The conductive composite has an excess anion group derived from the polyanion and has high dispersibility in water, so the dispersion medium other than water is preferably a water-soluble organic solvent. Here, the water-soluble organic solvent is an organic solvent having a dissolution amount of 1 g or more in 100 g of water at 20 °C, and examples thereof include alcohol solvents, ketone solvents, and ester solvents. The water-soluble organic solvent contained as the dispersion medium may be one kind or two or more kinds.

[0027] Examples of the alcohol-based solvents include methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 2-methyl-2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, allyl alcohol, ethylene glycol, propylene glycol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, and the like. Examples of the ether-based solvents include diethyl ether, dimethyl ether, propylene glycol dialkyl ether, diethylene glycol diethyl ether, and the like. Examples of the ketone-based solvents include diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisopropyl ketone, methyl ethyl ketone, acetone, diacetone alcohol, and the like. Examples of the nitrogen atom-containing solvents include N-methylpyrrolidone, dimethylacetamide, dimethylformamide, and the like. The water-soluble organic solvent may contain only one kind or may contain two or more kinds. Since the wettability of the conductive polymer dispersion with respect to the base material is improved, an alcohol-based solvent or a ketone-based solvent is preferable as the water-soluble organic solvent, and an alcohol-based solvent is more preferable.

[0028] The water content with respect to the total mass of the dispersion medium excluding the solid content (non-volatile component) of the conductive polymer dispersion is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and may be 100% by mass. When water is contained at or above the above lower limit value, the dispersibility of the conductive composite contained in the conductive polymer dispersion is enhanced, and the storage stability is improved. In addition, the ESR of the capacitor having a solid electrolyte layer formed from the conductive polymer dispersion can be further reduced.

[0029] The content of the water-soluble organic solvent relative to the total mass of the aqueous dispersion medium is preferably 30 to 70% by mass, more preferably 40 to 60% by mass or more. Further, the content of water relative to the total mass of the aqueous dispersion medium is preferably 70 to 30% by mass, more preferably 60 to 40% by mass or less. When it is within the above-mentioned preferred range, it is possible to improve the wettability with respect to the substrate while suppressing the temporal decrease in the dispersion stability of the conductive composite in the conductive polymer dispersion.

[0030] As the content of the conductive composite relative to the total mass of the conductive polymer dispersion, 0.01% by mass or more and 5.0% by mass or less is preferable, 1.0% by mass or more and 4.0% by mass or less is more preferable, and 1.5% by mass or more and 3.0% by mass or less is even more preferable. When it is equal to or higher than the lower limit value of the above range, the conductivity of the conductive layer formed by curing the conductive polymer dispersion can be further improved. When it is equal to or lower than the upper limit value of the above range, the dispersibility of the conductive composite in the conductive polymer dispersion can be enhanced, and the storage stability can be further enhanced.

[0031] The initial viscosity of the conductive polymer dispersion at 23°C (viscosity within 1 day after production) is preferably 25 mPa·s or less, more preferably 20 mPa·s or less, even more preferably 15 mPa·s or less, and particularly preferably 10 mPa·s or less when the concentration of the conductive composite with respect to the total mass of the conductive polymer dispersion is adjusted to 1.6% by mass. The lower limit value of the above viscosity is not particularly limited, and 1 mPa·s or more can be mentioned as a guideline. The increase rate of the viscosity after storage {= viscosity after storage ÷ initial viscosity × 100%} of the conductive polymer dispersion having the above viscosity after standing and storing at 20 to 25°C for 2 weeks is preferably lower, for example, less than 190%. If it is less than 190%, it can be said that the storage stability is sufficiently high. When measuring the above viscosity, the dispersion medium contained in the conductive polymer dispersion is preferably only ion-exchanged water. Further, the conductive polymer dispersion for measuring the viscosity may contain an anionic surfactant, but it is preferably free of other additives. The measurement of the viscosity was carried out at 23°C using a tuning fork vibration viscometer in accordance with JIS Z8803:2011 (Method for Measuring Viscosity by Vibration Viscometer).

[0032] (Anionic surfactant) The conductive polymer dispersion of this embodiment may further contain an anionic surfactant different from the polyanion constituting the conductive composite. By containing an anionic surfactant, the initial viscosity before storage can be reduced, and the storage stability can also be improved.

[0033] As the anionic surfactant, those having a hydrophilic sulfonic acid group and a hydrophobic hydrocarbon group in the molecule are preferred. Specifically, for example, linear alkylbenzene sulfonic acids such as dodecylbenzenesulfonic acid (DBSA) or salts thereof are preferred. Also included are branched alkylbenzene sulfonic acids, alkylsulfonic acids, alkyl phosphate esters, alkyl carboxylic acids, and salts thereof.

[0034] The content of the anionic surfactant with respect to the total mass of the conductive polymer dispersion is preferably, for example, 0.001% by mass or more and 1.0% by mass or less, more preferably 0.01% by mass or more and 0.50% by mass or less, and even more preferably 0.10% by mass or more and 0.30% by mass or less. When it is at or above the above lower limit value, the initial viscosity of the conductive polymer dispersion can be further reduced, and the storage stability can also be further improved. When it is at or below the above upper limit value, foaming of the conductive polymer dispersion can be reduced, and a decrease in the conductivity of the conductive layer, which is a cured product thereof, can be reduced.

[0035] (Polyol compound) The conductive polymer dispersion may contain one or more polyol compounds. Here, the polyol compound refers to a compound having two or more hydroxy groups, which is different from the π-conjugated conductive polymer, the polyanion, and the anionic surfactant. By containing a polyol compound, the conductivity of the conductive layer, which is a cured product of the conductive polymer dispersion, can be further increased.

[0036] Examples of the polyol compound include one or more selected from ethylene glycol, diethylene glycol, propylene glycol, 1,4 - butanediol, glycerin, pentaerythritol, trimethylolpropane, and trimethylolethane.

[0037] The content of the polyol compound contained in the conductive polymer dispersion is preferably, for example, 100 parts by mass or more and 10,000 parts by mass or less, more preferably 200 parts by mass or more and 2,000 parts by mass or less, and even more preferably 300 parts by mass or more and 1,000 parts by mass or less, based on 100 parts by mass in total of the π - conjugated conductive polymer and the polyanion. When it is within the above - mentioned preferred range, the coatability of the conductive polymer dispersion is improved, and the ESR of the capacitor can be further reduced.

[0038] The content of the polyol compound with respect to the total mass of the conductive polymer dispersion is preferably 1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less, and even more preferably 1% by mass or more and 5% by mass or less. When it is within the above - mentioned preferred range, the coatability of the conductive polymer dispersion is improved, and the ESR of the capacitor can be further reduced.

[0039] (Optional additive) The conductive polymer dispersion of this aspect may contain an arbitrary additive other than the conductive composite within a range not impairing the gist of the present invention, and the content ratio thereof can be appropriately determined according to the type of the additive. For example, it can be 1 to 1,000 parts by mass based on 100 parts by mass in total of the π - conjugated conductive polymer and the polyanion. Here, the arbitrary additive is a compound other than the anionic surfactant, the polyol compound, and the dispersion medium.

[0040] Examples of the arbitrary additive include surfactants, inorganic conductive agents, defoaming agents, coupling agents, antioxidants, ultraviolet absorbers, and the like. Examples of surfactants include nonionic, anionic, and cationic surfactants, among which nonionic surfactants are preferred in terms of storage stability. Additionally, polymer surfactants such as polyvinyl alcohol and polyvinyl pyrrolidone may be added. Examples of inorganic conductive agents include metal ions and conductive carbon. Metal ions can be generated by dissolving metal salts in water. Examples of defoaming agents include silicone resins, polydimethylsiloxane, and silicone oil. Examples of coupling agents include silane coupling agents having vinyl groups, amino groups, epoxy groups, etc. Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, sugars, etc. Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, oxanilide-based ultraviolet absorbers, hindered amine-based ultraviolet absorbers, benzoate-based ultraviolet absorbers, etc.

[0041] ≪Method for Producing Conductive Composite≫ The conductive composite of the first aspect of the present invention can be produced, for example, by the following method.

[0042] <Step A> First, in Step A, an aqueous polyanion solution is prepared. Step A is a step of adding a polymerization initiator to a first reaction solution containing a polymerizable anion monomer and water to obtain a second reaction solution containing a polyanion formed by polymerization of the polymerizable anion monomer.

[0043] The polymerizable anion monomer is an organic compound that forms a polyanion upon polymerization and has at least one anion group in one molecule. The anion group is a functional group that can be ionized in water and may form a salt with a cation such as sodium or potassium. The polymerizable anionic monomer used in this process is preferably one or more selected from known monomers capable of forming the polyanions exemplified above. Among them, styrenesulfonic acid or its salt, which can form polystyrenesulfonic acid, is most preferred as it is particularly excellent as a dopant for π-conjugated conductive polymers. The blending amount of the polymerizable anionic monomer relative to the total mass of the first reaction solution is preferably, for example, 1.0 to 20.0% by mass, more preferably 5.0 to 15.0% by mass, and even more preferably 8.0 to 13.0% by mass. When it is above the lower limit value of the above range, the yield per reaction increases and the production efficiency is enhanced. When it is below the upper limit value of the above range, the amount of low molecular weight polyanion formed can be reduced.

[0044] Examples of the polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. The blending amount of the polymerization initiator relative to the total mass of the first reaction solution is, for example, 0.1 to 1.0% by mass.

[0045] The completion of the polymerization reaction of the polyanion in Step A is judged by the fact that all the polymerization initiator added to the first reaction solution has been consumed. For example, when reacting with stirring at 70 to 95°C, the reaction can be completed in about 4 to 12 hours.

[0046] The second reaction solution contains the formed polyanion. When the anion group of the polyanion forms a salt with a counter cation, it is preferable to contact it with a cation exchange resin to remove the cation. Usually, the second reaction solution contains a high molecular weight polyanion polymerized to Mw of 10,000 or more, preferably 50,000 or more, and a low molecular weight anion polymerized to Mw of less than 10,000 or less than about 5,000. In order to surely obtain the conductive composite of the first aspect, it is preferable to obtain an aqueous polyanion solution from which the low molecular weight anion has been removed.

[0047] As a method for removing and purifying low-molecular-weight anions from the second reaction solution, for example, an ultrafiltration method or an anion exchange resin adsorption method can be mentioned. In the ultrafiltration method, low-molecular-weight anions permeate through the ultrafiltration membrane while high-molecular-weight polyanions do not, so the two can be separated. In the anion exchange resin adsorption method, if an anion exchange resin to which low-molecular-weight anions are preferentially likely to bind is used, low-molecular-weight anions are adsorbed while high-molecular-weight polyanions are hardly adsorbed, so the two can be separated. Examples of such anion exchange resins include Duolite A368MS manufactured by Sumika Chemtex Corporation.

[0048] The Mw of the main peak on the high-molecular-weight side of the polyanion in the polyanion aqueous solution obtained in Step A is preferably 90,000 to 200,000, more preferably 120,000 to 200,000, and even more preferably 140,000 to 200,000. Here, Mw is the average molecular weight on a mass basis measured using GPC as described above and determined in terms of pullulan conversion. When it is within the above range, the conductive composite of the first aspect can be easily obtained.

[0049] Also, in the GPC analysis of the polyanion aqueous solution obtained in Step A, usually one or two peaks are observed in the GPC chart of the polyanion aqueous solution. Among these peaks, the ratio represented by PSSA2 / PSSA1 of the area PSSA1 of the main peak on the high-molecular-weight side and the area PSSA2 of the sub-peak on the low-molecular-weight side is preferably lower, and preferably in the order of 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, 0.5% or less, 0% (the sub-peak is below the detection limit). When it is within the above range, the conductive composite of the first aspect can be easily obtained.

[0050] Furthermore, in the GPC analysis of the polyanion aqueous solution obtained in Step A, the Mw of the main peak on the high-molecular-weight side of the polyanion is preferably 90,000 to 200,000, more preferably 120,000 to 200,000, and even more preferably 140,000 to 200,000. Similarly, the Mw of the sub-peak on the low-molecular-weight side of the polyanion is preferably 500 to 2000. When it is within the above range, the storage stability of the conductive polymer dispersion containing the conductive composite of this aspect is further enhanced.

[0051] <Engineering B> Next, in Engineering B, in the presence of a polyanion, a π-conjugated conductive polymer is formed by a polymerization reaction to obtain a conductive composite. Engineering B is a step of adding a polymerizable monomer that forms a π-conjugated conductive polymer and an optional radical polymerization initiator to the aqueous polyanion solution obtained in Engineering A, and forming the π-conjugated conductive polymer, thereby obtaining a third reaction solution containing a conductive composite in which the π-conjugated conductive polymer and the polyanion are complexed. In Engineering B, a third reaction solution containing a conductive composite can be obtained by a known method except for using the aqueous polyanion solution obtained in Engineering A.

[0052] The polymerizable monomer that forms the π-conjugated conductive polymer is preferably one or more selected from known monomers that can form the π-conjugated conductive polymer exemplified above. Among them, 3,4-ethylenedioxythiophene, which can form PEDOT with excellent conductivity and heat resistance, is most preferred.

[0053] Examples of the radical polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. It is preferable to blend a catalyst such as a transition metal compound such as ferric chloride, ferric sulfate, ferric nitrate, and cupric chloride into the reaction solution together with the radical polymerization initiator.

[0054] The blending amount of the radical polymerization initiator relative to the total mass of the reaction solution during the polymerization reaction is preferably, for example, 0.10% by mass or more and 1.50% by mass or less, more preferably 0.30% by mass or more and 1.30% by mass or less, and even more preferably 0.50% by mass or more and 1.20% by mass or less.

[0055] The content of the monomer relative to the total mass of the reaction solution during the polymerization reaction is preferably, for example, 0.01% by mass or more and 2.0% by mass or less, more preferably 0.1% by mass or more and 1.0% by mass or less, and even more preferably 0.3% by mass or more and 0.8% by mass or less. The content of the polyanion with respect to the total mass of the reaction solution during the polymerization reaction is preferably, for example, 0.1% by mass or more and 3.0% by mass or less, more preferably 0.5% by mass or more and 2.0% by mass or less, and even more preferably 1.0% by mass or more and 1.5% by mass or less. By setting it within the above preferred range, an electroconductive polymer dispersion in which the concentration of the electroconductive composite is the above-described preferred content can be easily obtained.

[0056] As the reaction temperature in the reaction solution, for example, it can be 20 to 30°C. At the above reaction temperature, the polymerization reaction usually finishes in about 4 to 12 hours. The completion of the polymerization reaction can be known by measuring the amount of unreacted monomers in the reaction solution by means such as gas chromatography.

[0057] It is preferable to remove the residues of the catalyst and the radical polymerization initiator added to the reaction solution from the electroconductive polymer dispersion after the polymerization reaction. As the removal method, for example, a method of bringing the electroconductive polymer dispersion into contact with an ion exchange resin to adsorb the catalyst and the radical polymerization initiator to the ion exchange resin, a method of removing the electroconductive polymer dispersion by ultrafiltration to remove it together with the replacement of the dispersion medium, etc. can be mentioned. Among these, the method using an ion exchange resin is preferable because it is simple. It is preferable to use a cation exchange resin and an anion exchange resin in combination for the ion exchange resin.

[0058] The electroconductive polymer dispersion may be subjected to a dispersion treatment by a conventional method such as a high-pressure homogenizer.

[0059] An anionic surfactant, a polyol compound, an arbitrary additive, etc. may be further added to the electroconductive polymer dispersion obtained above.

[0060] ≪Method for manufacturing an electroconductive laminate≫ The third aspect of the present invention is a method for manufacturing an electroconductive laminate, including a step of coating at least a part of the surface of a substrate with the electroconductive polymer dispersion of the second aspect to form an electroconductive layer.

[0061] As a method of applying (coating) the conductive polymer dispersion liquid to an arbitrary surface of a substrate, for example, methods using coaters such as gravure coaters, roll coaters, curtain flow coaters, spin coaters, bar coaters, reverse coaters, kiss coaters, fountain coaters, rod coaters, air doctor coaters, knife coaters, blade coaters, cast coaters, screen coaters, etc., methods using sprayers such as air spray, airless spray, rotor damming, etc., dipping methods such as dip, etc. can be applied.

[0062] The coating amount of the conductive polymer dispersion liquid on the substrate is not particularly limited. For example, as the non-volatile component, it is preferably in the range of 0.01 to 10.0 g / m 2 is preferred.

[0063] A conductive layer can be formed by drying the coating film composed of the conductive polymer dispersion liquid applied on the substrate to remove at least a part of the dispersion medium and curing it. Examples of the method for drying the coating film include heat drying and vacuum drying. As heat drying, for example, methods such as hot air heating and infrared heating can be adopted. When applying heat drying, the heating temperature is appropriately set according to the dispersion medium used, but usually it is within the range of 50°C or higher and 200°C or lower. Here, the heating temperature is the set temperature of the drying device. The preferred drying time in the above heating temperature range is preferably 0.5 minutes or more and 30 minutes or less, and more preferably 1 minute or more and 15 minutes or less.

[0064] ≪Conductive laminate≫ The conductive laminate manufactured by the manufacturing method of the third aspect includes a substrate and a conductive layer formed on at least a part of the surface of the substrate, and the conductive layer contains a cured product of the conductive polymer dispersion liquid of the second aspect.

[0065] [Conductive layer] The formation range of the conductive layer may be the entire surface of any surface of the substrate, or a part thereof. In the conductive film, it is preferable that a conductive layer having a substantially uniform thickness is formed on substantially the entire surface of one side or the other side of the film substrate. When the conductive layer is formed only on a part of the surface of the substrate, for example, the conductive layer may be a fine conductive pattern such as a circuit or an electrode, or the region where the conductive layer is provided and the region where it is not provided may exist on the same surface and be roughly divided.

[0066] As the average thickness of the conductive layer, for example, 10 nm or more and 100 μm or less is preferable, 20 nm or more and 50 μm or less is more preferable, and 30 nm or more and 30 μm or less is even more preferable. If the average thickness of the conductive layer is equal to or greater than the lower limit value, high conductivity can be exhibited, and if it is equal to or less than the upper limit value, the adhesion of the conductive layer to the substrate is further improved.

[0067] [Substrate] The substrate may be a substrate made of an insulating material or a substrate made of a conductive material. The shape of the substrate is not particularly limited, and examples thereof include shapes mainly composed of a plane such as a film or a substrate. Examples of the insulating material include glass, synthetic resin, ceramics, etc. Examples of the conductive material include metal, conductive metal oxide, carbon, etc.

[0068] (Film substrate) When a film substrate is used as the substrate, the conductive laminate becomes a conductive film. Examples of the film base material include plastic films made of synthetic resins. Examples of the synthetic resin include ethylene-methyl methacrylate copolymer resin, ethylene-vinyl acetate copolymer resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacrylate, polycarbonate, polyvinylidene fluoride, polyarylate, styrene-based elastomer, polyester-based elastomer, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyimide, cellulose triacetate, cellulose acetate propionate, and the like. From the viewpoint of enhancing the adhesion between the film base material and the conductive layer, the synthetic resin for the film base material is preferably a polyester resin, and among them, polyethylene terephthalate is preferable.

[0069] The synthetic resin for the film base material may be amorphous or crystalline. The film base material may be unstretched or stretched. The film base material may be subjected to surface treatment such as corona discharge treatment, plasma treatment, flame treatment, etc. in order to further improve the adhesion to the conductive layer.

[0070] The average thickness of the film base material is preferably 5 μm or more and 500 μm or less, and more preferably 20 μm or more and 200 μm or less. If the average thickness of the film base material is at least the lower limit value, it becomes difficult to break, and if it is at most the upper limit value, sufficient flexibility as a film can be ensured. The average thickness of the film base material is a value obtained by measuring the thickness at 10 randomly selected locations and averaging the measured values.

[0071] (Glass substrate) Examples of the glass substrate include an alkali-free glass substrate, a soda-lime glass substrate, a borosilicate glass substrate, a fused silica glass substrate, etc. When the substrate contains an alkali component, the conductivity of the conductive layer tends to decrease. Among these glass substrates, an alkali-free glass is preferred. Here, the alkali-free glass refers to a glass composition in which the content of the alkali component is 0.1% by mass or less based on the total mass of the glass composition.

[0072] The average thickness of the glass substrate is preferably 100 μm or more and 3000 μm or less, more preferably 100 μm or more and 1000 μm or less. If the average thickness of the glass substrate is at least the lower limit value, it becomes difficult to break, and if it is at most the upper limit value, it can contribute to thinning of the conductive laminate. The average thickness of the glass substrate is a value obtained by measuring the thickness at 10 randomly selected locations and averaging the measured values.

[0073] ≪Method for manufacturing a capacitor≫ A fourth aspect of the present invention is a method for manufacturing a capacitor, which includes a step of applying the conductive polymer dispersion liquid of the second aspect onto the surface of a dielectric layer formed on the surface of an anode made of a porous body of valve metal and drying it to form a solid electrolyte layer.

[0074] The method for manufacturing a capacitor of this aspect preferably includes a step of oxidizing the surface of an anode 11 made of a porous body of valve metal to form a dielectric layer (dielectric formation step), a step of arranging a cathode at a position facing the dielectric layer (cathode formation step), and a step of forming a solid electrolyte layer on at least a part of the surface of the dielectric layer (film formation step). Hereinafter, each step will be described with reference to FIG. 1.

[0075] [Dielectric formation step] In this step, the surface of an anode 11 made of a porous body of valve metal is oxidized to form a dielectric layer 12. The method for forming the dielectric layer 12 is not particularly limited, and examples thereof include a method of anodizing the surface of the anode 11 in an electrolytic solution for formation treatment such as an ammonium adipate aqueous solution, an ammonium borate aqueous solution, or an ammonium phosphate aqueous solution.

[0076] [Cathode Formation Process] In this process, the cathode 13 is disposed at a position facing the dielectric layer 12. The method of disposing the cathode 13 is not particularly limited. For example, there are a method of forming the cathode 13 using a conductive paste such as a carbon paste or a silver paste, and a method of disposing a metal foil such as an aluminum foil so as to face the dielectric layer 12.

[0077] [Film Formation Process] In this process, the solid electrolyte layer 14 is formed by applying the above-described conductive polymer dispersion liquid to at least a part of the surface of the dielectric layer 12 and drying it.

[0078] As a method of applying the conductive polymer dispersion liquid, for example, dipping (dip coating), comma coating, reverse coating, lip coating, microgravure coating, etc. can be applied. Among these, a method of dipping the anode 11 into the conductive polymer dispersion liquid under reduced pressure is preferable. In the case of the dipping method, the conductive polymer dispersion liquid can be sufficiently applied to the inside of the porous structure on the surface of the dielectric layer 12. After dipping, it is taken out and the next drying treatment is carried out.

[0079] Examples of the drying method include drying at room temperature, hot air drying, far-infrared drying, etc. Among these, hot air drying is preferable. As the drying temperature, for example, 100 to 180 °C is preferable, and 120 to 150 °C is more preferable. As the drying time, for example, 0.2 to 1 hour is preferable. After the drying treatment, the capacitor may be assembled by a conventional method.

[0080] ≪Capacitor≫ The capacitor manufactured in the fourth aspect of the present invention includes an anode made of a porous body of valve metal, a dielectric layer made of an oxide of the valve metal, a cathode made of a conductive material provided on the opposite side of the dielectric layer from the anode, and a solid electrolyte layer formed between the dielectric layer and the cathode, and the solid electrolyte layer contains a cured product of the conductive polymer dispersion liquid of the second aspect.

[0081] An example of an embodiment of the capacitor will be described with reference to FIG. 1. The capacitor 10 shown in FIG. 1 includes an anode 11 made of a porous body of valve metal, a dielectric layer 12 made of an oxide of valve metal, a solid electrolyte layer 14 formed on the surface of the dielectric layer 12, and a cathode 13 provided on the outermost side. The cathode 13 is provided on the opposite side of the anode 11 with the dielectric layer 12 and the solid electrolyte layer 14 interposed therebetween.

[0082] Examples of the valve metal constituting the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Among these, aluminum, tantalum, and niobium are preferable. Specific examples of the anode 11 include those obtained by etching an aluminum foil to increase the surface area and then subjecting the surface to an oxidation treatment, and those obtained by subjecting the surface of a sintered body of tantalum particles or niobium particles to an oxidation treatment to form pellets. Those treated in this way become a porous body with irregularities formed on the surface.

[0083] The dielectric layer 12 in the present embodiment is a layer formed by oxidizing the surface of the anode 11, and is formed, for example, by anodizing the surface of the metal anode 11 in an electrolytic solution such as an ammonium adipate aqueous solution. Like the anode 11, irregularities are also formed on the dielectric layer 12.

[0084] As the cathode 13 in the present embodiment, a metal layer made of a conductive substance such as a conductive layer formed from a conductive paste or an aluminum foil can be used.

[0085] The solid electrolyte layer 14 in the present embodiment is formed on the surface of the dielectric layer 12. The solid electrolyte layer 14 covers at least a part of the surface of the dielectric layer 12, and may cover the entire surface of the dielectric layer 12. The thickness of the solid electrolyte layer 14 may be constant or may not be constant, and examples thereof include a thickness of 1 μm or more and 100 μm or less.

[0086] [Electrolytic solution] The capacitor may have an electrolytic solution that impregnates the solid electrolyte layer. Examples of the solvent constituting the electrolytic solution include alcohol solvents such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, and glycerin; lactone solvents such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; sulfur solvents such as sulfolane, dimethyl sulfoxide, and dimethyl sulfone; amide solvents such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide, and N-methylpyrrolidinone; nitrile solvents such as acetonitrile and 3-methoxypropionitrile; and water. Examples of the electrolyte constituting the electrolytic solution include organic acids such as adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, formic acid, 1,6-decanedicarboxylic acid, and 5,6-decanedicarboxylic acid; octanedicarboxylic acids such as 1,7-octanedicarboxylic acid; azelaic acid, sebacic acid, and the like; or boric acid, a polyhydric alcohol complex compound of boric acid obtained from boric acid and a polyhydric alcohol; inorganic acids such as phosphoric acid, carbonic acid, and silicic acid, etc. as anionic components, and primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, etc.), secondary amines (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.), tertiary amines (trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo(5,4,0)-undecene-7, etc.), tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.), etc. as cationic components; and the like.

[0087] The capacitor is not limited to the above configuration, and a separator may be provided between the dielectric layer and the cathode. Examples of the capacitor in which a separator is provided between the dielectric layer and the cathode include a wound capacitor. Examples of the separator include sheets (including nonwoven fabrics) made of, for example, cellulose, polyvinyl alcohol, polyester, polyethylene, polystyrene, polypropylene, polyimide, polyamide, polyvinylidene fluoride, etc., and nonwoven fabrics of glass fibers. The density of the separator is, for example, 0.1 g / cm 3 or more and 1.0 g / cm 3 or less. When providing a separator, a method of forming a cathode by impregnating the separator with carbon paste or silver paste can also be applied.

Examples

[0088] <Production of polyanion> [Production Example 1; PSS, Mw 170000, peak area ratio 2.5%] 110 g of sodium styrenesulfonate was dissolved in 820 ml of ion-exchanged water, and while stirring at 80°C, 4.88 g of sodium peroxydisulfate previously dissolved in 55 ml of water was added dropwise over 2 hours, and the solution was stirred for 4 hours. A cation exchange resin was added to the obtained sodium polystyrenesulfonate-containing solution to remove sodium ions. The solid content of the obtained aqueous solution 1 of polystyrenesulfonic acid (PSS) was 10% by mass. Regarding PSS aqueous solution 1, using an HPLC (high performance liquid chromatography) system equipped with a GPC (gel permeation chromatography) column and a differential refractive index detector, the weight average molecular weight was measured using pullulan manufactured by Showa Denko KK as a standard substance. When analyzing the GPC chart where the vertical axis represents the signal intensity of the differential refractive index and the horizontal axis represents the retention time, the peak of the first polystyrenesulfonic acid showed a weight average molecular weight (Mw) of 170000, and the peak of the second polystyrenesulfonic acid showed Mw of 1300. The peak area ratio (PSSA2 / (PSSA1 + PSSA2)×100) of these was 2.5%.

[0089] [Production Example 2; PSS, Mw 170000, peak area ratio 0%] To 1000 g of the PSS aqueous solution 1 produced in Production Example 1, 50 g of an anion exchange resin (Duolite A368MS, manufactured by Sumika Chemtex Corporation) was added and stirred for 1 hour. Thereafter, it was filtered, and the solid content of the PSS aqueous solution 2 obtained by removing the anion exchange resin was 8.5% by mass. When the PSS aqueous solution 2 was analyzed by GPC in the same manner as in Production Example 1, the second peak on the low molecular weight side had disappeared, and the peak area ratio was 0%. From this result, it was found that the PSS on the low molecular weight side was adsorbed and removed by the anion exchange resin. On the other hand, it was found that the PSS on the high molecular weight side did not enter the porous structure of the anion exchange resin, was not adsorbed, and was recovered in the filtrate.

[0090] [Production Example 3; PSS, Mw 170000, peak area ratio 3.1%] 4.88 g of sodium peroxydisulfate dissolved in 55 ml of water was changed to 5.69 g, and it was added dropwise over 2 hours, and the solution was stirred for 2 hours. Otherwise, it was carried out in the same manner as in Production Example 1 to obtain a PSS aqueous solution 3 having a solid content of 10% by mass. When the PSS aqueous solution 3 was analyzed by GPC in the same manner as in Production Example 1, the second peak on the low molecular weight side was present, and the peak area ratio was 3.1%.

[0091] [Production Example 4; PSS, Mw 120000, peak area ratio 4.7%] 4.88 g of sodium peroxydisulfate dissolved in 55 ml of water was changed to 8.54 g, and it was carried out in the same manner as in Production Example 1 to obtain a PSS aqueous solution 4 having a solid content of 10% by mass. When the PSS aqueous solution 4 was analyzed by GPC in the same manner as in Production Example 1, the second peak on the low molecular weight side was present, and the peak area ratio was 4.7%.

[0092] [Production Example 5; PSS, Mw 120000, peak area ratio 0%] To 1000 g of the PSS aqueous solution 4 produced in Production Example 4, 75 g of an anion exchange resin was added and stirred for 1 hour. Thereafter, it was filtered, and the solid content of the PSS aqueous solution 5 obtained by removing the anion exchange resin was 8.2% by mass. When the PSS aqueous solution 5 was analyzed by GPC in the same manner as in Production Example 1, the second peak on the low molecular weight side had disappeared as in Production Example 2, and the peak area ratio was 0%.

[0093] [Production Example 6; PSS, Mw 100000, peak area ratio 5.1%] Except that 4.88 g of sodium peroxydisulfate dissolved in 55 ml of water was changed to 9.76 g, the procedure was the same as in Production Example 1 to obtain a PSS aqueous solution 6 with a solid content of 10% by mass. When the PSS aqueous solution 6 was analyzed by GPC in the same manner as in Production Example 1, the second peak on the low molecular weight side was present, and the peak area ratio was 5.1%.

[0094] [Production Example 7; PSS, Mw 100000, peak area ratio 0%] 100 g of an anion exchange resin was added to 1000 g of the PSS aqueous solution 6 produced in Production Example 6, and the mixture was stirred for 1 hour. Then, it was filtered to remove the anion exchange resin, and the solid content of the obtained PSS aqueous solution 7 was 8.2% by mass.

[0095] <Example 1> 5.71 g of 3,4-ethylenedioxythiophene, 142.5 g of the PSS aqueous solution 1 obtained in Production Example 1, and 777.55 g of ion-exchanged water were mixed. This mixed solution was kept at 26°C, and while stirring, an oxidation catalyst solution of 1.15 g of ferric sulfate dissolved in 18.05 g of ion-exchanged water was added. 6.25 g of sodium peroxydisulfate dissolved in 50.55 g of ion-exchanged water was gradually added dropwise in a fixed amount over 2 hours, and the mixture was further stirred for 4 hours to cause a reaction. A cation exchange resin (manufactured by Sumitomo Chemical Tex Co., Ltd., Duolite C255LFH) and an anion exchange resin (manufactured by Sumitomo Chemical Tex Co., Ltd., Duolite A368S) were added to the obtained reaction solution to remove the polymerization initiator and iron. As a result, a blue PEDOT-PSS aqueous dispersion with a PEDOT:PSS = 1:2.5 (mass ratio) was obtained. The solid content (non-volatile component) of the obtained dispersion was adjusted to 1.6% by mass by ultrafiltration.

[0096] <Example 2> The PSS aqueous solution 1 was changed to 167.94 g of the PSS aqueous solution 2 obtained in Production Example 2, and the amount of ion-exchanged water compounded was changed to 750.36 g. Otherwise, the procedure was the same as in Example 1, and a 1.6 mass% PEDOT-PSS aqueous dispersion was obtained.

[0097] <Example 3> The PSS aqueous solution 1 was changed to 174.09 g of the PSS aqueous solution 5 obtained in Production Example 5, and the amount of ion-exchanged water compounded was changed to 747.21 g. Otherwise, the procedure was the same as in Example 1, and a 1.6 mass% PEDOT-PSS aqueous dispersion was obtained.

[0098] <Example 4> The PSS aqueous solution 1 was changed to 174.09 g of the PSS aqueous solution 7 obtained in Production Example 7, and the amount of ion-exchanged water compounded was changed to 747.21 g. Otherwise, the procedure was the same as in Example 1, and a 1.6 mass% PEDOT-PSS aqueous dispersion was obtained.

[0099] <Example 5> The PSS aqueous solution 1 was changed to 167.94 g of the PSS aqueous solution 2 obtained in Production Example 2, the amount of ion-exchanged water compounded was changed to 748.93 g, and 1.43 g of dodecylbenzenesulfonic acid was added. Otherwise, the procedure was the same as in Example 1, and a 1.6 mass% PEDOT-PSS aqueous dispersion was obtained.

[0100] <Example 6> The PSS aqueous solution 1 was changed to 174.09 g of the PSS aqueous solution 6 obtained in Production Example 7, the amount of ion-exchanged water compounded was changed to 742.79 g, and 1.43 g of dodecylbenzenesulfonic acid was added. Otherwise, the procedure was the same as in Example 1, and a 1.6 mass% PEDOT-PSS aqueous dispersion was obtained.

[0101] <Comparative Example 1> The PSS aqueous solution 1 was changed to the PSS aqueous solution 3 obtained in Production Example 3. Otherwise, the procedure was the same as in Example 1, and a 1.6 mass% PEDOT-PSS aqueous dispersion was obtained.

[0102] <Comparative Example 2> The PSS aqueous solution 1 was changed to the PSS aqueous solution 4 obtained in Production Example 4, and the procedure was the same as in Example 1 to obtain a 1.6 mass% PEDOT-PSS aqueous dispersion.

[0103] <Comparative Example 3> The PSS aqueous solution 1 was changed to the PSS aqueous solution 6 obtained in Production Example 6, and the procedure was the same as in Example 1 to obtain a 1.6 mass% PEDOT-PSS aqueous dispersion.

[0104] <Evaluation of Viscosity> The viscosity at 23°C of the PEDOT-PSS aqueous dispersion with a solid content concentration of 1.6 mass% obtained in each example was measured using a vibrating viscometer. The measurement results of the initial viscosity are shown in Table 1. The above viscosity is the value measured at 23°C using a tuning fork vibrating viscometer in accordance with JIS Z8803:2011 (Viscosity Measurement Method by Vibration Viscometer).

[0105] <Evaluation of Storage Stability> The viscosity of the conductive polymer dispersion obtained in each example was measured after storing it at 24°C for 2 weeks. The measurement results of the viscosity after storage and the calculated value as the increase rate (%) based on the ratio to the initial viscosity are shown in Table 1 It should be noted that the lower the increase rate, the less the viscosity change and the better the storage stability.

[0106] <Evaluation of Conductivity> To 1.9 g of the conductive polymer dispersion (PEDOT-PSS aqueous dispersion) obtained in each example, 4.0 g of methanol and 0.1 g of propylene glycol were added and thoroughly mixed to form a paint. This paint was applied to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., Lumirror T60) using a No. 12 bar coater, and a conductive film was obtained by heating and drying at a drying temperature of 120°C for 1 minute. The surface resistance value of the obtained conductive film was measured using a resistivity meter (Loresta manufactured by Nitto Seiko Analytic Co., Ltd.) under the condition of an applied voltage of 10V. The results are shown in Table 1. The lower the value of the surface resistance, the higher and better the conductivity.

[0107]

Table 1

[0108] From the above, it is clear that Examples 1 to 6 according to the present invention can form a conductive layer exhibiting good conductivity, and a highly storage-stable conductive polymer dispersion liquid with a low viscosity maintained during storage can be obtained. In particular, the low initial viscosity rates of Examples 5 to 6 to which an anionic surfactant is added are remarkable.

Explanation of Reference Numerals

[0109] 10 Capacitor 11 Anode 12 Dielectric layer 13 Cathode 14 Solid electrolyte layer

Claims

1. A conductive composite comprising a π-conjugated conductive polymer and a polyanion, wherein, for an aqueous polyanion solution in which the polyanion is dissolved independently of the π-conjugated conductive polymer in an aqueous solvent, when analyzed by a gel permeation chromatography system, among the detection signal intensities corresponding to the content of the polyanion, the ratio represented by PSSA2 / PSSA1 of the area PSSA1 of the main peak on the high molecular weight side and the area PSSA2 of the sub-peak on the low molecular weight side is 2.5% or less. A conductive composite.

2. The analysis by the gel permeation chromatography system measures the weight average molecular weight of the polyanion using pullulan with a known weight average molecular weight as a standard, The conductive composite according to claim 1, wherein the weight average molecular weight of the main peak is 90,000 to 200,000.

3. The conductive composite according to claim 2, wherein the weight average molecular weight of the sub-peak is 500 to 2000.

4. The conductive composite according to claim 1, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene).

5. The conductive composite according to claim 3, wherein the polyanion is polystyrene sulfonic acid.

6. A conductive polymer dispersion comprising the conductive composite according to any one of claims 1 to 5 and water.

7. The conductive polymer dispersion according to claim 6, further comprising an anionic surfactant different from the polyanion.

8. The conductive polymer dispersion according to claim 7, wherein the anionic surfactant is linear alkylbenzene sulfonic acid or a salt thereof.

9. A conductive laminate comprising a substrate and a conductive layer formed on at least a part of the surface of the substrate, wherein the conductive layer contains a cured product of the conductive polymer dispersion according to claim 6.

10. A capacitor comprising an anode made of a porous body of valve metal, a dielectric layer made of an oxide of the valve metal, a cathode made of a conductive material provided on the side opposite to the anode of the dielectric layer, and a solid electrolyte layer formed between the dielectric layer and the cathode, wherein the solid electrolyte layer contains a cured product of the conductive polymer dispersion according to claim 6.

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