Method for producing a conductive polymer dispersion, method for producing a conductive laminate, and method for producing a capacitor

Abstract

The present invention provides a method for producing a low-viscosity conductive polymer dispersion, a method for producing a conductive laminate using the conductive polymer dispersion, and a method for producing a capacitor. [Solution] A method for producing a conductive polymer dispersion, comprising the steps of adding a polymerization initiator to a reaction solution containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal to initiate a polymerization reaction, thereby forming a conductive composite containing the π-conjugated conductive polymer and the polyanion, wherein an inorganic halide is added to the reaction solution to carry out the polymerization reaction.

Description

Technical Field

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

Background Art

[0002] A π-conjugated conductive polymer whose main chain is composed of a π-conjugated system forms a conductive complex by doping with a polyanion having an anion group, and exhibits dispersibility in water. A method for producing a capacitor has been disclosed in which a paint containing a conductive polymer dispersion containing a conductive complex 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] By the way, the above-mentioned conductive polymer dispersion used in the production of a capacitor and a paint containing the same are required to have a low viscosity in order to penetrate into the porous structure of the dielectric layer. Further, the solid electrolyte layer formed by drying the coating film is required to have high conductivity. Conventional conductive polymer dispersions have not always been able to satisfy these requirements.

[0005] The present invention provides a method for producing a conductive polymer dispersion having a low viscosity, a method for producing a conductive laminate using the conductive polymer dispersion, and a method for producing a capacitor. [Means for solving the problem]

[0006] [1] A method for producing a conductive polymer dispersion, comprising the step of adding a polymerization initiator to a reaction solution containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal, to initiate a polymerization reaction to form a conductive composite containing the π-conjugated conductive polymer and the polyanion, wherein an inorganic halide is added to the reaction solution to carry out the polymerization reaction. [2] A method for producing a conductive polymer dispersion according to [1], wherein an aqueous polyanion solution containing the polyanion is prepared in advance for incorporation into the reaction solution, and free anions contained in the aqueous polyanion solution are removed before incorporation into the reaction solution. [3] The method for producing a conductive polymer dispersion according to [1] or [2], wherein the inorganic halide is one or more selected from hydrogen halides and alkali metal halides. [4] A method for producing a conductive polymer dispersion according to any one of [1] to [3], wherein the inorganic halide is a bromine compound, an iodine compound, or a chlorine compound. [5] A method for producing a conductive polymer dispersion according to any one of [1] to [4], wherein the inorganic halide contains a bromide ion, an iodide ion, or a chloride ion as an anion, and a sodium ion, a potassium ion, or a proton as a cation. [6] The method for producing a conductive polymer dispersion according to [5], wherein the content of the anion relative to the content of the polyanion in the reaction solution is 100 ppm or more and 50,000 ppm or less by mass. [7] A method for producing a conductive polymer dispersion according to any one of [1] to [6], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene). [8] A method for producing a conductive polymer dispersion according to any one of [1] to [7], wherein the polyanion is polystyrene sulfonic acid. A method for producing a conductive laminate, comprising the steps of: obtaining a conductive polymer dispersion by the manufacturing method described in any of [9] [1] to [8]; and applying the conductive polymer dispersion to at least a portion of the surface of a substrate and drying it to form a conductive layer. A method for manufacturing a capacitor, comprising the steps of: obtaining a conductive polymer dispersion by a manufacturing method described in any one of the items [1] to [8]; and applying the conductive polymer dispersion to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying it to form a solid electrolyte layer. [Effects of the Invention]

[0007] According to the present invention, a method for producing a conductive polymer dispersion with low viscosity can be provided. The conductive polymer dispersion produced by this invention has a moderately low viscosity, allowing it to easily penetrate the porous structure of the dielectric layer used in the manufacture of capacitors, thus enabling the production of high-performance capacitors. The conductive polymer dispersion produced by the present invention has a moderately low viscosity, so when applied to a substrate, it can form a coating of uniform thickness, making it possible to manufacture a high-performance conductive laminate.

[0008] This invention is believed to contribute to SDG Goal 12, "Responsible Consumption and Production."

[0009] In this specification and the claims, the lower and upper limits of the numerical ranges indicated by "~" are to be included within those numerical ranges. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing one embodiment of the capacitor of the present invention. [Modes for carrying out the invention]

[0011] ≪Method for producing conductive polymer dispersions≫ A first aspect of the present invention is a method for producing a conductive polymer dispersion, comprising the step of adding a polymerization initiator to a reaction solution containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal, to initiate a polymerization reaction, thereby forming a conductive composite containing the π-conjugated conductive polymer and the polyanion.

[0012] (Inorganic halides) In this embodiment, the polymerization reaction is carried out by adding an inorganic halogen to the reaction solution. The inorganic halide in this embodiment can be any water-soluble one that provides halide ions into the reaction solution. The halide ions, together with the polyanions, dope the π-conjugated conductive polymer by weaving through the gaps between the polyanions, while suppressing the three-dimensional aggregation (entanglement) of the conductive composite containing the π-conjugated conductive polymer and the polyanions. As a result, the viscosity of the produced conductive polymer dispersion is thought to be kept low.

[0013] In this embodiment, the inorganic halide is preferably one or more selected from hydrogen halides and alkali metal halides, from the viewpoint of further lowering the viscosity of the conductive polymer dispersion. If the cation constituting the halide is a proton or an alkali metal, the influence on the conductivity of the conductive composite can be reduced.

[0014] The inorganic halide in this embodiment is preferably a bromine compound, an iodine compound, or a chlorine compound. The anions of these halides can be easily doped with a π-conjugated conductive polymer. Specifically, examples include those containing a bromide ion, an iodide ion, or a chloride ion as the anion (halide ion), and a sodium ion, a potassium ion, or a proton as the cation.

[0015] The inorganic halide contained in the reaction solution may be one kind or two or more kinds. From the viewpoint of sufficiently reducing the viscosity of the produced conductive polymer dispersion, the content ratio of the anion to the content of the polyanion is preferably 100 ppm or more and 50,000 ppm or less on a mass basis, and within this range, 200 ppm or more and 10,000 ppm or less, 300 ppm or more and 8,000 ppm or less, 400 ppm or more and 6,000 ppm or less, 500 ppm or more and 5,000 ppm or less, 500 ppm or more and 2,500 ppm or less, 500 ppm or more and 1,000 ppm or less may also be within the range.

[0016] As an example of a specific embodiment of this aspect, the following Step A and Step B can be mentioned.

[0017] <Step A (Preliminary Step)> 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 (aqueous polyanion solution) containing a polyanion formed by polymerization of the polymerizable anion monomer.

[0018] The polymerizable anion monomer is an organic compound that forms a polyanion when polymerized 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 an alkali metal ion such as sodium or potassium or ammonium. The polymerizable anion monomer used in this step is preferably one or more selected from known monomers that can form polyanions exemplified later. Among them, styrene sulfonic acid or its salt that can form polystyrene sulfonic acid, which is particularly excellent as a dopant for π-conjugated conductive polymers, is most preferred. Examples of the salt include alkali metal salts and ammonium salts. The blending amount of the polymerizable anion monomer with respect 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. If the value is above the lower limit of the above range, the yield per reaction increases, and the manufacturing efficiency improves. If the value is below the upper limit of the above range, the amount of low molecular weight polyanions formed can be reduced.

[0019] Examples of polymerization initiators include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. The amount of polymerization initiator relative to the total mass of the first reaction solution is, for example, 0.1 to 1.0% by mass.

[0020] The completion of the polyanion polymerization reaction in step A is indicated by the consumption of all the polymerization initiator added to the first reaction solution. For example, if the reaction is carried out with stirring at 70-95°C, the reaction may be completed in about 4-12 hours.

[0021] The second reaction solution contains the formed polyanion. If the anionic group of the polyanion forms a salt with a countercation, it is preferable to remove the cation by contacting it with a cation exchange resin. The second reaction solution preferably contains high molecular weight polyanions polymerized to have an Mw of 10,000 or more, preferably 50,000 or more, and more preferably 100,000 or more.

[0022] The second reaction solution may contain inorganic cations or inorganic anions derived from the raw materials. From the viewpoint of reducing the introduction of these free ions into the reaction solution of the subsequent step B, it is preferable to obtain a polyanion aqueous solution from which the inorganic ions contained in the second reaction solution have been removed, and then supply this to the reaction solution of step B. By pre-removing free cations, inorganic cations that form salts with the anionic groups of polyanions are removed, making it easier for these anionic groups to function as dopants for π-conjugated conductive polymers in step B. By pre-removing free anions, the significance of precisely adjusting the blending and concentration of inorganic halides in the reaction solution in step B increases, making it easier to obtain a low-viscosity conductive polymer dispersion in step B.

[0023] Methods for purifying polyanions by removing free ions from the second reaction solution include, for example, ultrafiltration and cation / anion exchange resin adsorption. In ultrafiltration, low molecular weight free ions permeate the ultrafiltration membrane, while high molecular weight polyanions do not, thus separating the two. In the cation-anion exchange resin adsorption method, low molecular weight free ions preferentially bind, while high molecular weight polyanions are not adsorbed, thus allowing for the separation of the two.

[0024] <Process B> Next, in step B, a polymerization initiator for polymerizing the monomer is added to a reaction solution containing a polyanion, a monomer for forming a π-conjugated conductive polymer, an aqueous dispersion medium, an inorganic halide, and a catalyst containing a transition metal to initiate a polymerization reaction and form a conductive composite containing the π-conjugated conductive polymer and the polyanion.

[0025] Step B is preferably a step in which a polymerizable monomer for forming a π-conjugated conductive polymer, the inorganic halide, the catalyst, and an optional radical polymerization initiator are added to the aqueous polyanion aqueous solution obtained in Step A to form 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 combined. The polyanion aqueous solution used in step B may be the one obtained in step A, or it may be an aqueous solution prepared by dissolving a commercially available polyanion in water. If the commercially available polyanion contains free inorganic ions, it is preferable to remove these before using it in step B.

[0026] In step B, a third reaction solution containing the conductive composite can be obtained by known methods, except for the addition of an inorganic halide to the reaction solution.

[0027] The polymerizable monomer that forms the π-conjugated conductive polymer is preferably one or more selected from known monomers that can form π-conjugated conductive polymers, as illustrated later. Among these, 3,4-ethylenedioxythiophene, which can form PEDOT with excellent conductivity and heat resistance, is most preferred.

[0028] The catalyst containing the transition metal is preferably one that decomposes the polymerization initiator to generate radicals and does not contain halide ions. From the viewpoint of enhancing this catalytic activity, the catalyst is preferably one that contains an iron compound or a copper compound, and more preferably one that contains an iron compound. Specifically, examples include ferric sulfate, ferric nitrate, and ferric citrate. The reaction solution may contain one type of catalyst or two or more types.

[0029] The content of the catalyst relative to the total mass of the reaction solution immediately before the addition of the polymerization initiator is preferably, for example, 0.01% by mass or more and 0.50% by mass or less, more preferably 0.05% by mass or more and 0.35% by mass or less, and even more preferably 0.10% by mass or more and 0.20% by mass or less. Within the above preferred range, a conductive polymer dispersion containing a conductive composite with excellent conductivity can be obtained more easily.

[0030] The polymerization initiator can be any agent that promotes or initiates polymerization by chemical oxidation of the monomer, and is preferably a radical polymerization initiator commonly used in the production of polymers that does not contain halide ions. The polymerization initiator is preferably one that decomposes under the action of the catalyst to generate radicals, and preferably one that has a peracid structure represented by "-SO2-OO-" in its molecule. Specifically, peroxodisulfate or its salt, or peroxomonosulfate or its salt are preferred. Here, the salt has a countercation such as sodium, potassium, or ammonium. Among these, peroxodisulfate (persulfate) is more preferred. The polymerization initiator added to the reaction solution may be one type or two or more types.

[0031] It is preferable to add the polymerization initiator last to the reaction solution after all the other materials have been mixed. It is preferable to dissolve the polymerization initiator in a small amount of water and add it to the reaction solution. The polymerization initiator may be added all at once or in stages. From the viewpoint of ensuring that the polymerization reaction proceeds stably, it is preferable to slowly add a fixed amount dropwise over a predetermined time (for example, 2 to 4 hours). With the dropwise method, a conductive polymer dispersion containing a conductive composite with excellent conductivity can be obtained more easily.

[0032] The amount of polymerization initiator added to the total mass of the reaction solution immediately before the addition of the polymerization initiator is preferably 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. Within the above preferred range, a conductive polymer dispersion containing a conductive composite with excellent conductivity can be obtained more easily.

[0033] The monomer content relative to the total mass of the reaction solution immediately before the addition of the polymerization initiator is preferably 0.1% by mass or more and 2.0% by mass or less, more preferably 0.3% by mass or more and 1.5% by mass or less, and even more preferably 0.5% by mass or more and 1.0% by mass or less. Within the above preferred range, a conductive polymer dispersion containing a conductive composite with excellent conductivity can be obtained more easily.

[0034] The content of the polyanion relative to the total mass of the reaction solution immediately before the addition of the polymerization initiator is preferably 0.3% by mass or more and 6.0% by mass or less, more preferably 1.0% by mass or more and 3.0% by mass or less, and even more preferably 1.5% by mass or more and 2.0% by mass or less. Within the above preferred range, a conductive polymer dispersion containing a conductive composite with excellent conductivity can be obtained more easily.

[0035] The reaction temperature in the reaction solution can be, for example, 20-30°C. At this reaction temperature, the polymerization reaction is usually completed in about 4-12 hours. The completion of the polymerization reaction can be determined by measuring the amount of unreacted monomers in the reaction solution using gas chromatography or the like.

[0036] It is preferable to remove the free ions derived from the inorganic halide added to the reaction solution, the catalyst, and the polymerization initiator residue from the conductive polymer dispersion after the polymerization reaction. Methods for removal include, for example, contacting a conductive polymer dispersion with an ion exchange resin to adsorb unwanted components onto the ion exchange resin, and removing the components along with the displacement of the dispersion medium by ultrafiltration of the conductive polymer dispersion. Of these, the method using an ion exchange resin is preferred because it is simple. It is preferable to use a combination of a cation exchange resin and an anion exchange resin.

[0037] The conductive polymer dispersion obtained above may be dispersed using conventional methods such as a high-pressure homogenizer, or other additives may be added.

[0038] <Conductive composite> Conductive composites contain π-conjugated conductive polymers and polyanions. In water, π-conjugated conductive polymers are positively charged and polyanions are negatively charged, so it is thought that the two form a composite mainly through electrostatic interaction. Typically, conductive composites are formed by polymerizing monomers of π-conjugated conductive polymers in water containing polyanions, and then spontaneously doping the resulting π-conjugated conductive polymer with polyanions.

[0039] In the polyanions constituting the conductive composite, only some anionic groups are doped into the π-conjugated conductive polymer, while there are excess anionic groups that do not participate in doping. Since these excess anionic groups are hydrophilic, the conductive composite is water-dispersible. When the total number of anionic groups in a polyanion is considered to be 100 mol%, the excess anionic groups are preferably 30 mol% to 90 mol%, and more preferably 45 mol% to 75 mol%.

[0040] (π-conjugated conductive polymers) Any organic polymer whose main chain is composed of a π-conjugated system can be used as the π-conjugated conductive polymer. Examples include 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. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferred, and from the viewpoint of transparency, polythiophene-based conductive polymers are more preferred.

[0041] 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), and poly(3-iodine). 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-Dodecyl 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-di Examples include dodecyloxythiophene, 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), and 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 due to its excellent conductivity, transparency, and heat resistance. The conductive composite may contain one type of π-conjugated conductive polymer, or two or more types.

[0042] (Polyanion) A polyanion is a polymer that has two or more monomer units containing anionic groups within its molecule. The anionic groups of this polyanion function as dopants for π-conjugated conductive polymers, thereby improving the conductivity of the π-conjugated conductive polymer. The anionic group of the polyanion is preferably a sulfo group or a carboxyl group. Specific examples of such polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic acid esters having sulfo groups, polymethacrylic acid esters having sulfo groups (for example, poly(4-sulfobutyl methacrylate, polysulfoethyl methacrylate, polymethacryloyloxybenzene sulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and other polymers having sulfo groups, as well as polymers having carboxyl groups such as polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropanecarboxylic acid), and polyisoprene carboxylic acid. Polyanions may be homopolymers formed by the polymerization of a single monomer, or copolymers formed by the polymerization of two or more monomers. Among these polyanions, polymers having sulfo groups are preferred because they can achieve higher conductivity, and polystyrene sulfonic acid is even more preferred.

[0043] The polyanion content in the conductive composite is preferably in the range of 1 to 1000 parts by mass, more preferably 10 to 700 parts by mass, and even more preferably 100 to 500 parts by mass, per 100 parts by mass of the π-conjugated conductive polymer. If the polyanion content is above the lower limit, the doping effect on the π-conjugated conductive polymer tends to be stronger, resulting in higher conductivity. On the other hand, if the polyanion content is below the upper limit, the content ratio of the π-conjugated conductive polymer becomes sufficient, ensuring sufficient conductivity.

[0044] <Conductive polymer dispersion> The conductive polymer dispersion produced in the first embodiment is a conductive polymer dispersion containing a conductive composite and water. The π-conjugated conductive polymer constituting the conductive composite may be doped with at least a portion of the halide ions derived from the inorganic halide blended into the reaction solution.

[0045] The polyanion content in the conductive polymer dispersion is preferably in the range of 1 to 1000 parts by mass, more preferably 10 to 700 parts by mass, and even more preferably 100 to 500 parts by mass, per 100 parts by mass of the π-conjugated conductive polymer. If the polyanion content is above the lower limit, the doping effect on the π-conjugated conductive polymer tends to be stronger, resulting in higher conductivity. On the other hand, if the polyanion content is below the upper limit, the π-conjugated conductive polymer can be sufficiently contained, thus ensuring sufficient conductivity.

[0046] The total content of π-conjugated conductive polymers and polyanions relative to the total mass of the conductive polymer dispersion 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 this preferred range, the dispersibility of the conductive composite is enhanced. Furthermore, the conductivity of the conductive layer formed from the conductive polymer dispersion can be further improved.

[0047] (dispersion medium) The dispersion medium contained in the conductive polymer dispersion is preferably an aqueous dispersion medium containing water, given that the conductive composite is hydrophilic. However, a dispersion medium other than water may also be included. 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 excess anionic groups derived from polyanions and exhibits high dispersibility in water; therefore, a water-soluble organic solvent is preferred as the dispersion medium other than water. Here, the water-soluble organic solvent is an organic solvent whose solubility in 100g of water at 20°C is 1g or more, and examples include alcohol-based solvents, ketone-based solvents, and ester-based solvents. The dispersion medium may consist of one or more water-soluble organic solvents.

[0048] Examples of 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, and ethylene glycol monomethyl ether. Examples of ether-based solvents include diethyl ether, dimethyl ether, propylene glycol dialkyl ether, and diethylene glycol diethyl ether. Examples of 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, and diacetone alcohol. Examples of nitrogen atom-containing solvents include N-methylpyrrolidone, dimethylacetamide, and dimethylformamide. The water-soluble organic solvent may contain only one type, or it may contain two or more types. Since the conductive polymer dispersion has good wettability with respect to the substrate, an alcohol-based solvent or a ketone-based solvent is preferred as the water-soluble organic solvent, and an alcohol-based solvent is more preferred.

[0049] The water content relative to the total mass of the dispersion medium, excluding the solid content (non-volatile components) of the conductive polymer dispersion, is preferably 40% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, and may also be 100% by mass. Including water at or above the lower limit of the above value improves the dispersibility of the conductive composite contained in the conductive polymer dispersion.

[0050] The content of the water-soluble organic solvent relative to the total mass of the aqueous dispersion medium is preferably 70% by mass or less, and more preferably 60% by mass or less. Within this preferred range, it is possible to improve the wettability to the substrate while suppressing the time-dependent decrease in the dispersion stability of the conductive composite in the conductive polymer dispersion.

[0051] The viscosity (in mPa·s) at 23°C of a conductive polymer dispersion prepared using only water as the dispersion medium, with the conductive composite content adjusted to 1.8% by mass, is preferably 10.0 to 30.0, more preferably 15.0 to 30.0, and even more preferably 20.0 to 30.0. If the value is above the lower limit mentioned above, it becomes easier to apply and adhere to a substrate such as a dielectric layer, and a thick solid electrolyte layer can be easily formed. When the value is below the upper limit mentioned above, it becomes easier for the material to penetrate the fine porous structure of the dielectric layer, allowing for the easy formation of a high-performance solid electrolyte layer. The viscosity measurements described above were taken at 23°C using a tuning fork vibrating viscometer, in accordance with JIS Z8803:2011 (Viscosity measurement method using vibrating viscometer).

[0052] (Optional additives) The conductive polymer dispersion of this embodiment may contain any additive other than the conductive composite, as long as it does not impair the spirit of the present invention. The proportion of the additive can be appropriately determined depending on the type of additive, but for example, it can be 1 to 1000 parts by mass per 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion. Here, the arbitrary additive is a compound other than the polyol compound and the dispersion medium.

[0053] Optional additives include, for example, surfactants, inorganic conductive agents, defoamers, coupling agents, antioxidants, and UV absorbers. Examples of surfactants include nonionic, anionic, and cationic surfactants, but nonionic surfactants are preferred in terms of storage stability. Polymer-based surfactants such as polyvinyl alcohol and polyvinylpyrrolidone may also 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, polydimethylsiloxanes, and silicone oils. 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, and sugars. Examples of UV absorbers include benzotriazole-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, oxanilide-based UV absorbers, hindered amine-based UV absorbers, and benzoate-based UV absorbers.

[0054] ≪Method for manufacturing conductive laminates≫ A second aspect of the present invention is a method for manufacturing a conductive laminate, comprising the steps of: obtaining a conductive polymer dispersion by the manufacturing method of the first aspect; and coating the conductive polymer dispersion onto at least a portion of the surface of a substrate and drying it to form a conductive layer.

[0055] Methods for coating (applying) a conductive polymer dispersion to any surface of a substrate include, 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, and screen coaters; methods using sprayers such as air sprayers, airless sprayers, and rotor dampening devices; and immersion methods such as dipping.

[0056] The amount of conductive polymer dispersion applied to the substrate is not particularly limited, but for example, 0.01 to 10.0 g / m² of non-volatile components is recommended. 2 A range of [specified range] is preferred.

[0057] A conductive layer can be formed by drying a coating film made of a conductive polymer dispersion applied to a substrate, removing at least a portion of the dispersion medium, and curing it. Methods for drying the coating include heat drying and vacuum drying. For heat drying, for example, methods such as hot air heating and infrared heating can be used. When applying heat drying, the heating temperature is set appropriately according to the dispersion medium used, but is usually within the range of 50°C to 200°C. Here, the heating temperature is the set temperature of the drying apparatus. Within the above heating temperature range, a suitable drying time is preferably 0.5 minutes to 30 minutes, and more preferably 1 minute to 15 minutes.

[0058] <Conductive laminate> The conductive laminate manufactured by the manufacturing method of the second embodiment comprises a substrate and a conductive layer formed on at least a portion of the surface of the substrate, wherein the conductive layer includes a cured product of the conductive polymer dispersion.

[0059] [Conductive layer] The area in which the conductive layer is formed may be the entire surface of any surface of the substrate, or it may be only a part of it. In the case of a conductive film, it is preferable that a conductive layer of substantially uniform thickness is formed on substantially the entire surface of one or the other surface of the film substrate. If the conductive layer is formed on only 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 area with the conductive layer and the area without the conductive layer may exist on the same surface and be roughly separated.

[0060] The average thickness of the conductive layer is preferably, for example, 10 nm to 100 μm, more preferably 20 nm to 50 μm, and even more preferably 30 nm to 30 μm. If the average thickness of the conductive layer is above the lower limit, high conductivity can be achieved, and if it is below the upper limit, the adhesion of the conductive layer to the substrate is further improved.

[0061] [Base material] The substrate may be made of an insulating material or a conductive material. The shape of the substrate is not particularly limited, and examples include mainly flat shapes such as films and substrates. Examples of insulating materials include glass, synthetic resins, and ceramics. Examples of conductive materials include metals, conductive metal oxides, and carbon.

[0062] (Film substrate) When a film substrate is used as the aforementioned substrate, the conductive laminate becomes a conductive film. Examples of the film substrate include plastic films made of synthetic resins. Examples of the synthetic resins 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 elastomer, polyester elastomer, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyimide, cellulose triacetate, and cellulose acetate propionate. From the viewpoint of improving adhesion between the film substrate and the conductive layer, the synthetic resin for the film substrate is preferably a polyester resin, and among these, polyethylene terephthalate is preferred.

[0063] The synthetic resin used for the film substrate may be amorphous or crystalline. The film substrate may be unstretched or stretched. The film substrate may be subjected to surface treatments such as corona discharge treatment, plasma treatment, or flame treatment in order to further improve the adhesion of the conductive layer.

[0064] The average thickness of the film substrate is preferably 5 μm to 500 μm, and more preferably 20 μm to 200 μm. If the average thickness of the film substrate is above the lower limit, it becomes less prone to tearing, and if it is below the upper limit, sufficient flexibility as a film can be ensured. The average thickness of the film substrate is the average of the measurements taken at 10 randomly selected locations.

[0065] (Glass substrate) Examples of glass substrates include alkali-free glass substrates, soda-lime glass substrates, borosilicate glass substrates, and quartz glass substrates. Since the presence of alkaline components in the substrate tends to reduce the conductivity of the conductive layer, alkali-free glass is preferred among the glass substrates. Here, alkali-free glass refers to a glass composition in which the content of alkaline components is 0.1% by mass or less of the total mass of the glass composition.

[0066] The average thickness of the glass substrate is preferably 100 μm to 3000 μm, and more preferably 100 μm to 1000 μm. If the average thickness of the glass substrate is above the lower limit, it becomes less prone to breakage, and if it is below the upper limit, it contributes to thinning the conductive laminate. The average thickness of the glass substrate is the average of the measurements taken at 10 randomly selected locations.

[0067] Capacitor manufacturing method A third aspect of the present invention is a method for manufacturing a capacitor, comprising the steps of obtaining a conductive polymer dispersion by the manufacturing method of the first aspect, and applying the conductive polymer dispersion to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying it to form a solid electrolyte layer.

[0068] The method for manufacturing a capacitor according to this embodiment preferably includes the steps of: oxidizing the surface of an anode made of a porous valve metal to form a dielectric layer (dielectric formation step); arranging a cathode at a position opposite the dielectric layer (cathode formation step); and forming a solid electrolyte layer on at least a part of the surface of the dielectric layer (film formation step). Each step will be described below with reference to Figure 1.

[0069] [Dielectric Formation Process] In this process, the surface of the anode 11, which is made of a porous valve metal, is oxidized to form a dielectric layer 12. The method for forming the dielectric layer 12 is not particularly limited, and examples include anodic oxidation of the surface of the anode 11 in an electrolyte solution for chemical treatment, such as an aqueous solution of ammonium adipate, an aqueous solution of ammonium borate, or an aqueous solution of ammonium phosphate.

[0070] [Cathode formation process] In this process, a cathode 13 is placed opposite the dielectric layer 12. The method of arranging the cathode 13 is not particularly limited, and examples include forming the cathode 13 using a conductive paste such as carbon paste or silver paste, or arranging a metal foil such as aluminum foil opposite the dielectric layer 12.

[0071] [Film forming process] This process involves applying the aforementioned conductive polymer dispersion to at least a portion of the surface of the dielectric layer 12 and drying it to form a solid electrolyte layer 14.

[0072] Methods for applying the conductive polymer dispersion include, for example, dip coating, comma coating, reverse coating, lip coating, and microgravure coating. Of these, the method of immersing the anode 11 in the conductive polymer dispersion under reduced pressure is preferred. With the dip method, the conductive polymer dispersion can be sufficiently applied to the interior of the porous structure on the surface of the dielectric layer 12. After immersion, it is removed and the drying process is carried out.

[0073] Drying methods include, for example, room temperature drying, hot air drying, and far-infrared drying. Among these, hot air drying is preferred. The drying temperature is preferably 100 to 180°C, and more preferably 120 to 150°C. The drying time is preferably 0.2 to 1 hour. After drying, the capacitor can be assembled using conventional methods.

[0074] <capacitor> A capacitor manufactured according to the third embodiment comprises 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.

[0075] An example of an embodiment of the capacitor described above will be explained with reference to Figure 1. The capacitor 10 shown in Figure 1 comprises an anode 11 made of a porous valve metal, a dielectric layer 12 made of an oxide of the 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 from the anode 11, with the dielectric layer 12 and the solid electrolyte layer 14 in between.

[0076] Examples of valve metals that constitute the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Of these, aluminum, tantalum, and niobium are preferred. Specific examples of anode 11 include aluminum foil that has been etched to increase its surface area and then oxidized, or sintered tantalum or niobium particles whose surface has been oxidized and formed into pellets. Materials processed in this way become porous bodies with irregularities formed on their surface.

[0077] In this embodiment, the dielectric layer 12 is a layer formed by oxidation of the surface of the anode 11. For example, it is formed by anodizing the surface of the metal anode 11 in an electrolyte such as an aqueous solution of ammonium adipate. Similar to the anode 11, the dielectric layer 12 also has irregularities formed on it.

[0078] In this embodiment, the cathode 13 can be a conductive layer formed from a conductive paste or a metal layer made of a conductive material such as aluminum foil.

[0079] In this embodiment, the solid electrolyte layer 14 is formed on the surface of the dielectric layer 12. The solid electrolyte layer 14 covers at least a portion 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 not; for example, a thickness of 1 μm or more and 100 μm or less is possible.

[0080] [Electrolyte] The capacitor may have an electrolyte that impregnates a solid electrolyte layer. Examples of solvents that constitute the electrolyte include alcohol-based solvents such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, and glycerin; lactone-based solvents such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; sulfur-based solvents such as sulfolane, dimethyl sulfoxide, and dimethyl sulfone; amide-based solvents such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide, and N-methylpyrrolidinone; nitrile-based solvents such as acetonitrile and 3-methoxypropionitrile; and water. The electrolytes constituting the electrolyte solution include, for example, adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, formic acid, decanedicarboxylic acids such as 1,6-decanedicarboxylic acid and 5,6-decanedicarboxylic acid, octanedicarboxylic acids such as 1,7-octanedicarboxylic acid, organic acids such as azelaic acid and sebacic acid; or boric acid, polyhydric alcohol complex compounds of boric acid obtained from boric acid and polyhydric alcohols; and inorganic acids such as phosphoric acid, carbonic acid, and silicic acid as anionic components, with primary amines (methylamine, ethylamine, propylamine, Examples include electrolytes with cationic components such as butylamine, ethylenediamine, secondary amines (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.), tertiary amines (trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo(5,4,0)-undecene-7, etc.), and tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.).

[0081] The capacitor is not limited to the configuration described above; a separator may be provided between the dielectric layer and the cathode. An example of a capacitor with a separator between the dielectric layer and the cathode is a wound-type capacitor. Examples of separators include sheets (including nonwoven fabrics) made of cellulose, polyvinyl alcohol, polyester, polyethylene, polystyrene, polypropylene, polyimide, polyamide, polyvinylidene fluoride, etc., and glass fiber nonwoven fabrics. The density of the separator is, for example, 0.1 g / cm³. 3 More than 1.0g / cm 3 The following are listed: When a separator is provided, a method can be applied in which carbon paste or silver paste is impregnated into the separator to form the cathode. [Examples]

[0082] (Manufacturing Example 1) Production of polystyrene sulfonic acid; Mw110000 110 g of sodium styrene sulfonate was dissolved in 820 ml of deionized water. While stirring at 80°C, 8.54 g of sodium peroxodisulfate, pre-dissolved in 55 ml of water, was added dropwise over 2 hours, and the solution was stirred for 4 hours. 330 g of cation exchange resin was added to the resulting sodium polystyrene sulfonate-containing solution to remove sodium ions. Subsequently, 80 g of anion exchange resin was added to remove sulfate ions. The solid content of the resulting polystyrene sulfonic acid (PSS) aqueous solution 1 was 8.9% by mass. For PSS aqueous solution 1, the weight-average molecular weight was measured using pullulan manufactured by Showa Denko K.K. as a standard substance, with a GPC (gel permeation chromatography) column and a differential refractive index detector in an HPLC (high-performance liquid chromatography) system. Analysis of the GPC chart, where the vertical axis represents the signal intensity of the differential refractive index and the horizontal axis represents the retention time, revealed that the first peak for polystyrene sulfonic acid showed a weight-average molecular weight (Mw) of 110,000.

[0083] [Example 1; Addition of NaCl] 6.86 g of 3,4-ethylenedioxythiophene, 182.02 g of an aqueous solution of polystyrene sulfonic acid obtained in Production Example 1, 0.136 g of NaCl, and 719.76 g of deionized water were mixed at 26°C. The resulting mixture was kept at 26°C and stirred while adding an oxidation catalyst solution of 1.38 g of ferric sulfate dissolved in 21.64 g of deionized water, and stirring was continued for 30 minutes. Next, 7.50 g of sodium peroxodisulfate dissolved in 60.70 g of deionized water was gradually added dropwise in a constant amount over 2 hours, and the reaction was continued with stirring for another 4 hours. A cation exchange resin (Duolite C255LFH, manufactured by Sumika Chemtex Co., Ltd.) and an anion exchange resin (Duolite A368S, manufactured by Sumika Chemtex Co., Ltd.) were added to the resulting reaction solution to remove the polymerization initiator and iron. This yielded a blue PEDOT-PSS aqueous dispersion with a PEDOT:PSS ratio of 1:2.4 (by mass). The solid content (non-volatile components) of the obtained dispersion was 1.8% by mass.

[0084] [Example 2; Addition of NaBr] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.89, NaCl was replaced with NaBr, and the amount of NaBr was set to 0.010 g.

[0085] [Example 3; Addition of NaBr] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.80, NaCl was replaced with NaBr, and the amount of NaBr was set to 0.104 g.

[0086] [Example 4; Addition of NaBr] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.86, NaCl was replaced with NaBr, and the amount of NaBr was set to 1.043 g.

[0087] [Example 5; Addition of NaI] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.89, NaCl was replaced with NaI, and the amount of NaI was set to 0.018 g.

[0088] [Example 6; Addition of KCl] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.88, NaCl was replaced with KCl, and the amount of KCl was set to 0.012 g.

[0089] [Example 7; Addition of KBr] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.89, NaCl was replaced with KBr, and the amount of KBr was set to 0.012 g.

[0090] [Example 8; Addition of KI] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.89, NaCl was replaced with KI, and the amount of KI was set to 0.011 g.

[0091] [Example 9; Addition of HBr] A PEDOT-PSS aqueous dispersion was obtained by following the same procedure as in Example 1, except that the amount of deionized water was changed to 719.89g, NaCl was replaced with a 48% concentration HBr aqueous solution, and the amount of HBr aqueous solution was set to 0.171g.

[0092] [Comparative Example 1] The procedure was carried out in the same manner as in Example 1, except that NaCl was not added, to obtain a PEDOT-PSS aqueous dispersion.

[0093] <Viscosity Evaluation> The viscosity of the PEDOT-PSS aqueous dispersion (solid content concentration 1.8% by mass) obtained in each example was measured at 23°C using a vibrating viscometer. The measurement results are shown in the table below. The viscosity values ​​mentioned above were measured at 23°C using a tuning fork vibrating viscometer in accordance with JIS Z8803:2011 (Viscosity measurement method using vibrating viscometer).

[0094] <Evaluation of conductivity> 5.0 g of the conductive polymer dispersion (PEDOT-PSS aqueous dispersion) obtained in each example was mixed thoroughly with 5.0 g of methanol and 0.25 g of dimethyl sulfoxide to prepare a paint. This paint was applied to polyethylene terephthalate film (Toray Industries, Ltd., Lumirror T60) using a No. 08 bar coater, and heated and dried at a drying temperature of 100°C for 1 minute to obtain a conductive film. The surface resistance of the obtained conductive film was measured using a resistivity meter (Loresta, Nitto Seiko Analytech Co., Ltd.) under an applied voltage of 10 V. The results are shown in the table below. A lower surface resistance value indicates higher and better conductivity.

[0095] [Table 1]

[0096] [Table 2]

[0097] From the above, the conductive polymer dispersions obtained by the manufacturing methods of Examples 1 to 9 according to the present invention had a sufficiently lower viscosity compared to Comparative Example 1. From this result, it is clear that, as stated above, they easily penetrate the porous structure of the dielectric layer and are suitable for the manufacture of high-performance capacitors and the like. [Explanation of Symbols]

[0098] 10 Capacitors 11 Anode 12 Dielectric layer 13 Cathode 14 Solid electrolyte layer

Claims

1. A method for producing a conductive polymer dispersion, comprising the steps of adding a polymerization initiator to a reaction solution containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal, to initiate a polymerization reaction, thereby forming a conductive composite containing the π-conjugated conductive polymer and the polyanion, The polymerization reaction is carried out by adding an inorganic halogen to the reaction solution. A method for producing a conductive polymer dispersion.

2. A method for producing a conductive polymer dispersion according to claim 1, comprising preparing in advance a polyanion aqueous solution containing the polyanion to be incorporated into the reaction solution, removing the free anions contained in the polyanion aqueous solution, and then incorporating it into the reaction solution.

3. The method for producing a conductive polymer dispersion according to claim 1, wherein the inorganic halide is one or more selected from hydrogen halides and alkali metal halides.

4. The method for producing a conductive polymer dispersion according to claim 1, wherein the inorganic halide is a bromine compound, an iodine compound, or a chlorine compound.

5. A method for producing a conductive polymer dispersion according to claim 1, wherein the inorganic halide contains a bromide ion, an iodide ion, or a chloride ion as an anion, and a sodium ion, a potassium ion, or a proton as a cation.

6. The method for producing a conductive polymer dispersion according to claim 5, wherein the content of the anion relative to the polyanion content in the reaction solution is 100 ppm or more and 50,000 ppm or less by mass.

7. A method for producing a conductive polymer dispersion according to claim 1, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene).

8. The method for producing a conductive polymer dispersion according to claim 7, wherein the polyanion is polystyrene sulfonic acid.

9. A method for producing a conductive laminate, comprising the steps of: obtaining a conductive polymer dispersion by a manufacturing method described in any one of claims 1 to 8; and applying the conductive polymer dispersion to at least a portion of the surface of a substrate and drying it to form a conductive layer.

10. A step of obtaining a conductive polymer dispersion by a manufacturing method described in any one of claims 1 to 8, A method for manufacturing a capacitor, comprising the steps of: applying the conductive polymer dispersion to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying it to form a solid electrolyte layer.

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