Conductive composite dispersion and method for producing the same, and method for producing a conductive laminate

Abstract

To improve storage stability of a conductive composite body dispersion using methyl ethyl ketone as a dispersion medium.SOLUTION: A conductive composite body includes π-conjugated conductive polymer and polyanion. A conductive composite body dispersion includes a dispersion medium. The dispersion medium includes methyl ethyl ketone and a glycol ether-based organic solvent whose boiling point is 100°C or above. A content of the methyl ethyl ketone is 50 mass% or more relative to a total mass of the dispersion medium. An anionic group not participating in dope of the polyanion has a bond with a quaternary ammonium group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a conductive composite dispersion containing a π-conjugated conductive polymer, a method for producing the same, and a method for producing a conductive laminate. [Background technology]

[0002] Conjugated conductive polymers form conductive composites by doping with polyanions containing anionic groups, resulting in dispersibility in water. Furthermore, dispersibility in organic solvents can be imparted by chemically modifying the anionic groups that do not participate in polyanion doping by reacting them with epoxy compounds or amine compounds. By coating a substrate with a dispersion of these conductive composites (sometimes called a conductive polymer dispersion / containing liquid), conductive films, capacitors, and the like with a conductive layer can be manufactured.

[0003] For example, Patent Document 1 discloses that a conductive layer with excellent resistance to atmospheric exposure can be formed by adding a specific isocyanuric acid derivative to a conductive polymer-containing liquid. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-112741 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, while methyl ethyl ketone (MEK) is a dispersion medium that can effectively disperse conductive composites, it has problems with storage stability. Specifically, when a conductive composite is dispersed in MEK and stored at 40°C (equivalent to room temperature in summer) for about a month, and then a conductive layer is formed, the conductivity is inferior to that before storage (see Comparative Examples 1-2 below).

[0006] The inventors diligently investigated combinations with other organic solvents to improve storage stability. In the process, they discovered that combining isopropyl alcohol (IPA) with MEK improved storage stability. However, they encountered a new problem: the conductive layer became whitened (brushed).

[0007] One of the objectives of this invention is to improve the storage stability of conductive composite dispersions using methyl ethyl ketone as a dispersion medium. [Means for solving the problem]

[0008] [1] A conductive composite dispersion comprising a conductive composite containing a π-conjugated conductive polymer and a polyanion, and a dispersion medium, wherein the dispersion medium contains methyl ethyl ketone and a glycol ether-based organic solvent having a boiling point of 100°C or higher, the content of the methyl ethyl ketone is 20% by mass or more relative to the total mass of the dispersion medium, and the anionic group that does not participate in doping the polyanion has a bond with a quaternary ammonium group. [2] The conductive composite dispersion according to [1], wherein the content of the glycol ether-based organic solvent is 25% by mass or more with respect to the total mass of the dispersion medium. [3] The conductive composite dispersion according to [1] or [2], wherein the glycol ether-based organic solvent comprises propylene glycol monomethyl ether. [4] The conductive composite dispersion according to any one of [1] to [3], wherein the π-conjugated conductive polymer comprises poly(3,4-ethylenedioxythiophene). [5] A conductive composite dispersion according to any one of [1] to [4], comprising the polyanion polystyrene sulfonic acid. [6] The conductive composite dispersion according to any one of [1] to [5], wherein the quaternary ammonium group has 4 to 40 carbon atoms. [7] The conductive composite dispersion according to any one of [1] to [6], wherein the quaternary ammonium group comprises at least one of a tetrabutylammonium group and a tetraoctylammonium group. [8] A method for producing a conductive composite dispersion, comprising: a reaction step of dropwise adding an aqueous dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in an organic solvent containing a quaternary ammonium; a precipitate recovery step of recovering precipitates produced by the reaction; a washing step of washing the precipitates with a washing solvent; and a dispersion step of mixing with a dispersion medium to disperse the precipitates, wherein the dispersion medium comprises methyl ethyl ketone and at least one glycol ether-based organic solvent having a boiling point of 100°C or higher. [9] A method for producing a conductive composite dispersion according to [8], comprising the glycol ether-based organic solvent propylene glycol monomethyl ether.

[10] A method for producing a conductive laminate, comprising coating at least a portion of a substrate with a conductive composite dispersion according to any one of [1] to [7] to form a conductive layer. [Effects of the Invention]

[0009] In the conductive composite dispersion of the present invention, MEK is blended with a glycol ether-based organic solvent having a boiling point of 100°C or higher, which improves storage stability and further suppresses brushing during the formation of the conductive layer. According to the method for producing a conductive composite dispersion of the present invention, a conductive composite dispersion with improved storage stability can be easily produced. According to the method for manufacturing a conductive laminate of the present invention, for example, if a film is used as the substrate, a conductive film can be easily manufactured.

[0010] This invention is believed to contribute to SDG Goal 12, "Responsible Consumption and Production."

[0011] 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. [Modes for carrying out the invention]

[0012] ≪Conductive composite dispersion liquid≫ The first aspect of the present invention is a conductive composite containing a π-conjugated conductive polymer and a polyanion, and a conductive composite dispersion liquid containing a dispersion medium. The dispersion medium includes methyl ethyl ketone (MEK) and a glycol ether-based organic solvent having a boiling point of 100 °C or higher (hereinafter sometimes simply referred to as "high-boiling glycol ethers"). Further, an anion group not involved in the doping of the polyanion has a bond with a quaternary ammonium group.

[0013] In the conductive composite dispersion liquid of this aspect, the conductive composite is dispersed in a dispersion medium containing MEK and high-boiling glycol ethers. In this specification, unless otherwise specified, dispersion and dissolution are not distinguished, and the dispersion medium and the solvent are not distinguished.

[0014] <Conductive composite> The conductive composite of this aspect 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 anion groups dope the π-conjugated conductive polymer, and there are surplus anion groups not involved in the doping. Since the surplus anion groups are hydrophilic groups, the conductive composite in which the surplus anion groups are not modified has water dispersibility.

[0015] (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 viewpoints of transparency and conductivity, polythiophene-based conductive polymers are more preferable.

[0016] 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.

[0017] (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. The aforementioned polyanions may be used individually or in combination of two or more types. The mass-average molecular weight of the polyanion is preferably between 20,000 and 1,000,000, and more preferably between 100,000 and 500,000. The mass-average molecular weight is the average molecular weight on a mass basis, determined by measuring it using gel filtration chromatography and converting it to pullulan equivalent.

[0018] The polyanion content in the conductive composite is preferably 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 amount of anionic groups that do not participate in doping is appropriately suppressed, making it easier to react the anionic groups with quaternary ammonium salts and convert the conductive composite to hydrophobic.

[0019] 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%.

[0020] In this embodiment, the excess anionic groups of the polyanion that do not participate in doping (hereinafter also referred to as "some anionic groups") are modified by reaction with a quaternary ammonium group. This reaction results in a form in which the quaternary ammonium group is bonded to some of the anionic groups.

[0021] (Chemical modification of polyanions) From the viewpoint of improving the dispersibility of the conductive composite in this embodiment, it is preferable that the quaternary ammonium has four monovalent organic groups bonded to a nitrogen atom. The number of carbon atoms in each organic group is preferably four or more. The upper limit of the number of carbon atoms in each organic group is not particularly limited, but considering the solubility and reactivity in the reaction solution, it is preferably 40 or less, more preferably 25 or less, and even more preferably 10 or less. Furthermore, from the viewpoint of improving storage stability, the lower limit of the number of carbon atoms in each organic group is preferably 3 or more, and more preferably 6 or more. Furthermore, the total number of carbon atoms in each organic group of the quaternary ammonium (the number of carbon atoms in the quaternary ammonium group formed after the reaction) is preferably 4 to 100, more preferably 4 to 40, even more preferably 16 to 40, and most preferably 24 to 40, from the viewpoint of improving storage stability. The number of carbon atoms in each organic group may be the same or different.

[0022] The quaternary ammonium used in the reaction with the polyanion may be a salt. The counteranion of the ammonium cation constituting the quaternary ammonium salt is preferably a halogen ion such as a bromide ion or chloride ion, or a hydroxyl ion, but may also be a hydrogen ion (proton).

[0023] The following substituent (C) is formed by the reaction of some of the anionic groups of the polyanio constituting the conductive composite with a quaternary ammonium compound.

[0024] (Substituent C) -N - , , , 14 , , 14 , , ,

[0027] , , 11 , , , ,

[0026] , 11 , , , R 11 R 12 R 13 R 14 ···(C)<s [In formula (C), R 11 ~R 14 are each independently a hydrocarbon group which may have a substituent.]

[0025] In the substituent (C), the leftmost bond represents that the negative charge of the anion group and the positive charge of the quaternary ammonium cation are bonded. Examples of the anion group that can be negatively charged include an anion group in which an active proton is bonded to an oxygen atom, such as "-SO3 - ".<00s000141>

[0026] R 11 ~R 14 in the chemical formula (C) are hydrocarbon groups which may have a substituent. R 11 ~R 14 in the chemical formula (C) are substituents derived from quaternary ammonium.[[ID=4s0]] Examples of the hydrocarbon group in the chemical formula (C) include an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and an aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a substituent. sExamples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and the like. Examples of the substituent of the aliphatic hydrocarbon group include a phenyl group, a hydroxyl group, and the like.<0ss000148>Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, and the like. Examples of the substituent of the aromatic hydrocarbon group include an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, and the like.

[0027] sThe quaternary ammonium salt is preferably water-insoluble. Here, being water-insoluble means that the solubility in 100 g of water at 20 °C is less than 1 g. Since non-water-soluble quaternary ammonium salts are highly reactive with polyanions in the reaction solution described later, the desired substituent (C) can be easily formed.

[0028] The quaternary ammonium salt is preferably a tetraalkylammonium salt, and more preferably a tetraalkylammonium halide. This is because it has high reactivity with polyanions, and the reaction product is less soluble in aqueous dispersion media and precipitates easily. As the counteranion halogen ion, bromide ions and chloride ions are preferred, and chloride ions are more preferred from the viewpoint of improving conductivity.

[0029] Specific examples of quaternary ammonium salts include tetraethylammonium salt, tetrapropylammonium salt, tetrabutylammonium salt, tetraoctylammonium salt, tetradecylammonium salt, tetraphenylammonium salt, tetrabenzylammonium salt, and tetranaphthylammonium salt. The alkyl groups constituting these quaternary ammonium salts may be linear or branched.

[0030] <Dispersion medium> The conductive composite dispersion of this embodiment includes a dispersion medium for dispersing the conductive composite, the dispersion medium comprising MEK and one or more high-boiling point glycol ethers.

[0031] From the viewpoint of improving the dispersibility of the conductive composite and reducing the initial surface resistance value R0 of the conductive layer described later, the MEK content is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, particularly preferably 60% by mass or more, and most preferably 70% by mass or more, relative to the total mass of the dispersion medium.

[0032] The content of high-boiling point glycol ethers is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, particularly preferably 60% by mass or more, and most preferably 70% by mass or more, relative to the total mass of the dispersion medium, from the viewpoint of improving the storage stability of the conductive composite dispersion and reducing the surface resistance value R1 of the conductive layer described later.

[0033] The dispersion medium may or may not contain other organic solvents or water. If the dispersion medium contains other organic solvents or water, the total content of these is preferably less than 10% by mass, more preferably less than 5% by mass, and even more preferably less than 1% by mass, relative to the total mass of the dispersion medium. Here, "other organic solvents" refers to organic solvents other than MEK and high-boiling point glycol ethers.

[0034] (High boiling point glycol ethers) The following are examples of glycol ether-based organic solvents with a boiling point of 100°C or higher at 1 atmosphere (760 mmHg). The temperature in parentheses is the boiling point. For example, ethylene glycol monomethyl ether (approx. 124°C), diethylene glycol monomethyl ether (approx. 193°C), ethylene glycol monoethyl ether (approx. 136°C), diethylene glycol monoethyl ether (approx. 196°C), ethylene glycol monoethyl ether acetate (approx. 156°C), diethylene glycol monoethyl ether acetate (approx. 217°C), ethylene glycol mono-n-butyl ether (approx. 168°C), diethylene glycol monobutyl ether (approx. 230°C), ethylene glycol monobutyl ether acetate (approx. 192°C), diethylene glycol monobutyl ether acetate (approx. 246°C), propylene glycol monomethyl ether (approx. 121°C) Examples include propylene glycol monomethyl ether acetate (approximately 146°C), dipropylene glycol dimethyl ether (approximately 171°C), propylene glycol monomethyl ether propionate (approximately 161°C), diethylene glycol dimethyl ether (approximately 162°C), triethylene glycol dimethyl ether (approximately 216°C), tetraethylene glycol dimethyl ether (approximately 276°C), ethylene glycol diethyl ether (approximately 121°C), diethylene glycol diethyl ether (approximately 188°C), diethylene glycol methyl ethyl ether (approximately 179°C), diethylene glycol dibutyl ether (approximately 255°C), and diethylene glycol monohexyl ether (approximately 258°C). The high-boiling point glycol ethers contained in the dispersion medium may be one type or two or more types.

[0035] The content of the modified conductive composite (conductive composite bonded to a quaternary ammonium group) relative to the total mass of the conductive composite dispersion in this embodiment can be, for example, 0.01% by mass or more and 5.0% by mass or less, preferably 0.05% by mass or more and 2.0% by mass or less, more preferably 0.1% by mass or more and 1.5% by mass or less, and even more preferably 0.2% by mass or more and 1.0% by mass or less. If the value is above the lower limit of the above range, the conductivity of the conductive layer formed by applying the conductive composite dispersion can be further improved. If the value is below the upper limit of the above range, the dispersibility and storage stability of the conductive composite in the conductive composite dispersion can be improved, and a uniform conductive layer can be formed.

[0036] Method for producing conductive composite dispersion A second aspect of the present invention is a method for producing a conductive composite dispersion, comprising: a reaction step of reacting a conductive composite containing a π-conjugated conductive polymer and a polyanion with a quaternary ammonium to obtain a modified conductive composite in which a quaternary ammonium group is bonded to some of the anionic groups of the polyanion; and a dispersion step of dispersing the modified conductive composite in a dispersion medium to obtain a conductive composite dispersion. The dispersion medium comprises methyl ethyl ketone and at least one glycol ether-based organic solvent having a boiling point of 100°C or higher. According to the manufacturing method of this embodiment, a conductive composite dispersion of the first embodiment can be obtained.

[0037] [Reaction Process] The method for modifying the excess anionic groups of the polyanions constituting the conductive composite by reacting them with quaternary ammonium is not particularly limited, and known methods can be applied. For example, one method is to contact the conductive composite with an organic ammonium solution obtained by dissolving a quaternary ammonium salt in an organic solvent. Specifically, examples include a method of mixing the organic ammonium solution with a powdered conductive composite to obtain a reaction solution, a method of adding the organic ammonium solution to an aqueous dispersion containing the conductive composite (aqueous dispersion of conductive polymer) to obtain a reaction solution, and a method of adding the aqueous dispersion of conductive polymer to the organic ammonium solution to obtain a reaction solution. Since the reaction product of the conductive composite and quaternary ammonium is hydrophobic, if the reaction solution contains an aqueous dispersion, the reaction product may precipitate in the solution. This precipitate can then be recovered as a modified conductive composite.

[0038] The organic solvent constituting the aforementioned organic ammonium solution may be one type or two or more types. Examples of the aforementioned organic solvents include methanol, ethanol, 1-propanol, isopropyl alcohol, n-butanol, t-butanol, and allyl alcohol.

[0039] The content of the quaternary ammonium salt in the reaction solution is preferably 10 parts by mass or more and 5000 parts by mass or less, more preferably 100 parts by mass or more and 1000 parts by mass or less, and even more preferably 150 parts by mass or more and 500 parts by mass or less, based on 100 parts by mass of the total mass of the π-conjugated conductive polymer and polyanion (i.e., conductive composite) to be reacted. When the value is above the lower limit of the above range, the reaction efficiency between the conductive composite and the quaternary ammonium increases, and the reaction product can be easily obtained. If the value is below the upper limit of the above range, it is possible to prevent a decrease in the conductivity of the conductive composite due to the inclusion of unreacted quaternary ammonium.

[0040] (Conductive polymer aqueous dispersion) A conductive polymer aqueous dispersion is a dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in an aqueous dispersion medium. Here, the aqueous dispersion medium is water, or a mixture of water and a water-soluble organic solvent. A water-soluble organic solvent is defined as one that dissolves at a rate of 1 g or more in 100 g of water (at 20°C). Examples of water-soluble organic solvents include alcohol-based solvents, ketone-based solvents, and ester-based solvents. The aqueous dispersion medium may contain one type of water-soluble organic solvent, or two or more types. The water content relative to the total mass of the aqueous dispersion medium is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 80% by mass or more, and may also be 100% by mass. A higher water content increases the dispersibility of the conductive composite, and consequently, the reaction efficiency with quaternary ammonium. Furthermore, the reaction product is more likely to precipitate in the reaction solution.

[0041] The content of π-conjugated conductive polymers and polyanions relative to the total mass of the conductive polymer aqueous dispersion is preferably 0.1% to 5% by mass, more preferably 0.5% to 2% by mass, and even more preferably 0.8% to 1.5% by mass. Within the above preferred range, the dispersibility of the π-conjugated conductive polymer and polyanion is increased, and the reaction efficiency with quaternary ammonium is enhanced.

[0042] Aqueous dispersions of conductive polymers can be obtained, for example, by chemical oxidation polymerization of monomers that form a π-conjugated conductive polymer in an aqueous solution of polyanions. Alternatively, commercially available aqueous dispersions of conductive composites may be used. Known catalysts and oxidizing agents can be used in the aforementioned chemical oxidation polymerization. Examples of catalysts include transition metal compounds such as ferric chloride, ferric sulfate, ferric nitrate, and cupric chloride. Examples of oxidizing agents include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. The reaction temperature for the chemical oxidation polymerization is not particularly limited and may be, for example, 5 to 40°C.

[0043] [Precipitate recovery process] The method for recovering the reaction product (modified conductive composite) generated in the reaction solution as a precipitate is not particularly limited and can be recovered by decantation or filtration, for example.

[0044] [Washing process] By washing the recovered reaction product with a washing solution such as alcohol or water, residual water, unreacted quaternary ammonium salts, and impurities contained in the conductive polymer aqueous dispersion can be removed from the reaction product. There are no particular restrictions on the washing method; for example, the washing solution may be poured over the reaction product, or the reaction product may be gently stirred in the washing solution.

[0045] [Drying process] The washed reaction product may be recovered and dried. The drying method is not particularly limited, and known powder drying methods such as natural drying, air drying, and heat drying can be applied.

[0046] [Dispersion process] The method for dispersing the resulting reaction product (modified conductive composite) in a dispersion medium is not particularly limited, and conventional methods for dispersing conductive composites can be applied. For example, a preferred method is to add the reaction product to the aforementioned dispersion medium and disperse it using a high-pressure homogenizer.

[0047] A preferred embodiment of this model includes a reaction step of dropping an aqueous dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in an organic solvent containing a quaternary ammonium; a precipitate recovery step of recovering the precipitate produced by the reaction; a washing step of washing the precipitate with a washing solvent; and a dispersion step of mixing the precipitate with a dispersion medium to disperse the precipitate, all of which are carried out in this order.

[0048] <<Conductive Laminate>> A third aspect of the present invention is a conductive laminate comprising a substrate and a conductive layer formed on at least a portion of the substrate, the conductive layer being a cured layer of the conductive composite dispersion of the first aspect. The conductive laminate of this embodiment can be manufactured by the manufacturing method of the fourth embodiment described later.

[0049] [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.

[0050] 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. The average thickness of the conductive layer is the average of the measurements taken at 10 randomly selected locations.

[0051] [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.

[0052] (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.

[0053] 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.

[0054] 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.

[0055] (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.

[0056] 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.

[0057] ≪Method for manufacturing conductive laminates≫ A fourth aspect of the present invention is a method for manufacturing a conductive laminate by using the conductive composite dispersion of the first aspect and performing the following steps 1 to 3 in order. This embodiment makes it possible to manufacture the conductive laminate of the third embodiment.

[0058] (Process 1) This process involves applying the conductive composite dispersion to at least a portion of the substrate to form a coating film, and then drying the coating film to form a conductive layer, thereby obtaining a conductive laminate.

[0059] The description of the substrate is the same as described above, so any redundant explanation will be omitted here.

[0060] Methods for coating (applying) the conductive composite 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.

[0061] There are no particular restrictions on the amount of conductive composite dispersion applied to the substrate, but considering uniform and even coating, as well as conductivity and film strength, the solid content should be approximately 0.01 g / m². 2 More than 10.0g / m 2 The following range is preferable.

[0062] The thickness of the coating film immediately after applying the conductive composite dispersion to the substrate is preferably, for example, 0.1 μm to 500 μm, more preferably 1 μm to 100 μm, and even more preferably 5 μm to 50 μm. The thickness of the coating can be adjusted, for example, by changing the grit size of the bar coater.

[0063] A conductive layer can be formed by drying a coating film of a conductive composite dispersion applied to a substrate, removing at least a portion of the dispersion medium, and then 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. After drying, UV irradiation may be performed to cure the binder components contained in the coating film.

[0064] Upon drying of the coating film, a conductive laminate is obtained in which a conductive layer is formed on any surface of the substrate. The average thickness of the conductive layer in the conductive laminate is preferably 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. The average thickness of the conductive layer is the average of the measurements taken at 10 randomly selected locations.

[0065] The surface resistance of the conductive layer formed using the initial conductive composite dispersion immediately after preparation can be, for example, 3500 Ω / □ or less, preferably 3000 Ω / □ or less, more preferably 2000 Ω / □ or less, and even more preferably 1000 Ω / □ or less. The surface resistance of the conductive layer formed using the conductive composite dispersion after storage at 40°C for one month following preparation can be, for example, 3500 Ω / □ or less, preferably 3000 Ω / □ or less, more preferably 2000 Ω / □ or less, and even more preferably 1000 Ω / □ or less. There is no particular lower limit to the surface resistance of the conductive layer, but 10Ω / □ is given as a guideline. [Examples]

[0066] (Manufacturing Example 1) Production of polystyrene sulfonic acid 206 g of sodium styrene sulfonate was dissolved in 1000 ml of deionized water, and while stirring at 80°C, 1.14 g of ammonium persulfate oxidizing agent solution, which had been previously dissolved in 10 ml of water, was added dropwise over 20 minutes, and the solution was stirred for 12 hours. To the obtained sodium styrenesulfonate-containing solution, 1000 ml of sulfuric acid diluted to 10% by mass was added, and approximately 1000 ml of the solvent from the polystyrenesulfonic acid-containing solution was removed by ultrafiltration. Next, 2000 ml of deionized water was added to the remaining solution, and approximately 2000 ml of solvent was removed by ultrafiltration to wash the polystyrenesulfonic acid with water. This washing procedure was repeated three times. The water in the resulting solution was removed under reduced pressure to obtain colorless, solid polystyrene sulfonic acid.

[0067] (Manufacturing Example 2) Preparation of a conductive polymer aqueous dispersion A solution of 14.2 g of 3,4-ethylenedioxythiophene and 36.7 g of polystyrene sulfonic acid dissolved in 2000 ml of deionized water was mixed at 20°C. The resulting mixture was kept at 20°C, and while stirring, a solution of 29.64 g of ammonium persulfate and 8.0 g of ferric sulfate, dissolved in 200 ml of deionized water, was slowly added as an oxidation catalyst, and the mixture was stirred for 3 hours to allow the reaction to proceed. 2000 ml of deionized water was added to the resulting reaction mixture, and approximately 2000 ml of solvent was removed by ultrafiltration. This procedure was repeated three times. Next, 200 ml of sulfuric acid diluted to 10% by mass and 2000 ml of deionized water were added to the obtained solution, and approximately 2000 ml of solvent was removed by ultrafiltration. 2000 ml of deionized water was added to the remaining solution, and approximately 2000 ml of the solution was removed by ultrafiltration. This procedure was repeated three times. Furthermore, 2000 ml of deionized water was added to the obtained solution, and approximately 2000 ml of solvent was removed by ultrafiltration. This procedure was repeated five times to obtain a 1.2% by mass polystyrene sulfonic acid-doped poly(3,4-ethylenedioxythiophene) (PEDOT-PSS aqueous dispersion) solution. The PSS content relative to the PEDOT-PSS solid content was 75% by mass.

[0068] (Manufacturing Example 3) 2.4 g of tetrabutylammonium bromide was dissolved in 100 g of ethanol to an organic layer. 100 g of the PEDOT-PSS aqueous dispersion prepared in Production Example 2 was added dropwise and the mixture was stirred for 30 minutes. The precipitate was filtered off, 100 g of methanol was added and the mixture was stirred for 30 minutes, after which the precipitate was filtered off again. This washing operation was repeated once more. As a result, 1.1 g of conductive composite was obtained.

[0069] (Manufacturing example 4) A conductive composite of 1.1 g was obtained in the same manner as in Preparation Example 3, except that 2.4 g of tetrabutylammonium bromide was replaced with 2.4 g of tetraoctylammonium bromide.

[0070] (Example 1) A conductive composite dispersion was obtained by adding 1.1 g of the conductive composite obtained in Production Example 3, 205.5 g of methyl ethyl ketone (MEK), and 69 g of propylene glycol monomethyl ether (PGM) and treating them with a high-pressure homogenizer. The obtained conductive composite dispersion was applied to a polyester film (Lumirror T60, manufactured by Toray Industries, Inc.) using a bar coater No. 8, and dried at 120°C for 2 minutes to obtain a conductive film.

[0071] (Example 2) A conductive composite dispersion was obtained by adding 1.1 g of the conductive composite obtained in Production Example 3, 69 g of methyl ethyl ketone, and 205.5 g of propylene glycol monomethyl ether to a high-pressure homogenizer and treating the mixture. A conductive film was then obtained using this dispersion in the same manner as in Example 1.

[0072] (Example 3) A conductive composite dispersion was obtained by adding 1.1 g of the conductive composite obtained in Production Example 3, 137.3 g of methyl ethyl ketone, and 137.3 g of propylene glycol monomethyl ether to a high-pressure homogenizer and treating the mixture. A conductive film was then obtained using this dispersion in the same manner as in Example 1.

[0073] (Example 4) A conductive film was obtained in the same manner as in Example 1, except that 1.1 g of the conductive composite obtained in Manufacturing Example 3 was replaced with 1.1 g of the conductive composite obtained in Manufacturing Example 4.

[0074] (Example 5) A conductive film was obtained in the same manner as in Example 2, except that 1.1 g of the conductive composite obtained in Manufacturing Example 3 was replaced with 1.1 g of the conductive composite obtained in Manufacturing Example 4.

[0075] (Example 6) A conductive film was obtained in the same manner as in Example 3, except that 1.1 g of the conductive composite obtained in Manufacturing Example 3 was replaced with 1.1 g of the conductive composite obtained in Manufacturing Example 4.

[0076] (Comparative Example 1) A conductive composite dispersion was obtained by adding 1.1 g of the conductive composite obtained in Production Example 3 to 274.5 g of methyl ethyl ketone and treating it with a high-pressure homogenizer. Using this dispersion, a conductive film was obtained in the same manner as in Example 1.

[0077] (Comparative Example 2) A conductive film was obtained in the same manner as in Comparative Example 1, except that 1.1 g of the conductive composite obtained in Manufacturing Example 3 was replaced with 1.1 g of the conductive composite obtained in Manufacturing Example 4.

[0078] (Comparative Example 3) A conductive composite dispersion was obtained by adding 1.1 g of the conductive composite obtained in Production Example 4, 205.5 g of methyl ethyl ketone, and 69 g of isopropyl alcohol (IPA) and treating with a high-pressure homogenizer. A conductive film was obtained using this dispersion in the same manner as in Example 1. However, brushing (whitening phenomenon) occurred in the formed conductive layer.

[0079] <Evaluation of conductivity> The surface resistance R0 of the conductive films prepared using the initial conductive composite dispersions prepared in each example was measured (unit: Ω / □: ohms per square). A resistivity meter (HIRESTA, manufactured by Mitsubishi Chemical Analytec Corporation) was used, and the applied voltage was 10V. The measurement results are shown in Table 1.

[0080] <Evaluation of storage stability> The conductive composite dispersions obtained in each example were placed in sealed bottles and stored in a 40°C constant temperature bath for one month. Afterward, conductive films were prepared using the stored conductive composite dispersions in the same manner as in each example, and their surface resistance R1 was measured. The measurement results are shown in Table 1.

[0081] A smaller surface resistance value (unit: Ω / □) in each measurement result indicates higher conductivity. Furthermore, a smaller rate of change (ratio of surface resistance values ​​expressed as R1 / R0) indicates that the decrease in conductivity over time after manufacturing was suppressed.

[0082] <Evaluation of the appearance of the dispersion> Table 1 shows the color tones of the initial conductive composite dispersions prepared in each example, and the conductive composite dispersions after being stored in a constant temperature bath at 40°C for one month.

[0083] [Table 1]

[0084] The conductive composite dispersions of each embodiment of the present invention were all able to form a good conductive layer and exhibited excellent storage stability. In Examples 5 and 6, the conductivity was even better after storage. The conductive composite dispersions of Comparative Examples 1 and 2 did not contain glycol ether-based organic solvents with a boiling point of 100°C or higher, and therefore exhibited poor storage stability. Furthermore, Comparative Example 1, which was initially blue, changed to black after storage. The conductive composite dispersion of Comparative Example 3 does not contain glycol ether-based organic solvents with a boiling point of 100°C or higher, but contains isopropyl alcohol, so it has good storage stability, but the conductive layer that is formed becomes white due to brushing.

Claims

1. A conductive composite comprising a π-conjugated conductive polymer and a polyanion, and a dispersion liquid of the conductive composite comprising a dispersion medium. The dispersion medium comprises methyl ethyl ketone and a glycol ether-based organic solvent with a boiling point of 100°C or higher. The methyl ethyl ketone content is 20% by mass or more relative to the total mass of the dispersion medium. The content of the glycol ether-based organic solvent is 25% by mass or more relative to the total mass of the dispersion medium. If the dispersion medium contains organic solvents other than the methyl ethyl ketone and the glycol ether-based organic solvent, or water, the total content of these is less than 10% by mass of the total mass of the dispersion medium. The aforementioned glycol ether-based organic solvent is propylene glycol monomethyl ether. The anionic group that does not participate in the doping of the polyanion has a bond with a quaternary ammonium group. A conductive composite dispersion in which the quaternary ammonium group has 4 to 40 carbon atoms.

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

3. The conductive composite dispersion according to claim 2, wherein the polyanion contains polystyrene sulfonic acid.

4. The conductive composite dispersion according to claim 1, wherein the quaternary ammonium group comprises at least one of a tetrabutylammonium group and a tetraoctylammonium group.

5. A method for producing a conductive composite dispersion, comprising: a reaction step of dropwise adding an aqueous dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in an organic solvent containing a quaternary ammonium; a precipitate recovery step of recovering the precipitate produced by the reaction; a washing step of washing the precipitate with a washing solvent; and a dispersion step of mixing with a dispersion medium to disperse the precipitate. The dispersion medium comprises methyl ethyl ketone and at least one glycol ether-based organic solvent having a boiling point of 100°C or higher. The methyl ethyl ketone content is 20% by mass or more relative to the total mass of the dispersion medium. The content of the glycol ether-based organic solvent is 25% by mass or more relative to the total mass of the dispersion medium. If the dispersion medium contains organic solvents other than the methyl ethyl ketone and the glycol ether-based organic solvent, or water, the total content of these is less than 10% by mass of the total mass of the dispersion medium. The aforementioned glycol ether-based organic solvent is propylene glycol monomethyl ether. The anionic group that does not participate in the doping of the polyanion has a bond with the quaternary ammonium group of the quaternary ammonium, A method for producing a conductive composite dispersion in which the quaternary ammonium group has 4 to 40 carbon atoms.

6. The method for producing a conductive composite dispersion according to claim 5, wherein the quaternary ammonium group comprises at least one of a tetrabutylammonium group and a tetraoctylammonium group.

7. A method for producing a conductive laminate, comprising coating at least a portion of a substrate with a conductive composite dispersion according to any one of claims 1 to 4 to form a conductive layer.

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