JP7654987B2 - Conductive polymer aqueous solution and conductive polymer film - Google Patents

Description

The present invention was made to develop a conductive polymer aqueous solution that can provide a conductive polymer that is both water-resistant and heat-resistant, and relates to a conductive polymer aqueous solution that contains a specific self-doped conductive polymer with high conductivity, a polystyrene sulfonate compound, and a silane compound, as well as a conductive polymer film obtained by drying the conductive polymer aqueous solution and an article coated with the conductive polymer.

Conductive polymer materials have been developed in which π-conjugated polymers, such as polyacetylene, polythiophene, polyaniline, and polypyrrole, are doped with electron-accepting compounds as dopants, and applications to, for example, antistatic agents, solid electrolytes for capacitors, conductive paints, electromagnetic wave shields, electrochromic elements, electrode materials, thermoelectric conversion materials, transparent conductive films, chemical sensors, actuators, etc. are being considered. Among these conductive polymer materials, polythiophene-based conductive polymer materials are particularly useful in practical applications due to their chemical stability.

Polythiophene-based conductive polymer materials include PEDOT:PSS aqueous dispersion solutions (so-called externally doped conductive polymers) obtained by polymerizing 3,4-ethylenedioxythiophene (EDOT) in an aqueous solution of polystyrene sulfonic acid (PSS) as a dopant, and self-doped conductive polymers that have substituents (sulfo groups, sulfonate groups, etc.) that combine water solubility and doping properties directly or via a spacer in the polymer main chain, such as PEDOT-S (see, for example, Patent Document 1 and Non-Patent Documents 1 and 2).

Conductive polymers are being widely investigated for use as antistatic agents and as solid electrolytes in solid electrolytic capacitors, and there have been reports of using conductive polymers to increase the capacity and reduce the ESR of solid electrolytic capacitors.

International Publication No. 2014/007299

Journal of American Chemical Society, 112, 2801-2803 (1990) Advanced Materials, Vol. 23 (38) 4403-4408 (2011)

The present invention aims to provide an aqueous conductive polymer solution that improves the water resistance and heat resistance of a conductive film containing a self-doped conductive polymer.

As a result of intensive research aimed at solving the above problems, the present inventors discovered that an aqueous conductive polymer solution containing specific concentrations of the water-soluble self-doped conductive polythiophene (A), the water-soluble polystyrene sulfonate compound (B), and the silane compound (C) specified in the present invention can form a conductive film that is more water-resistant and heat-resistant than conventionally known compositions, and thus completed the present invention.

That is, the present invention resides in the following.

[1]
A conductive polymer aqueous solution containing a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), a polystyrene sulfonic acid compound (B), and a silane compound (C), wherein the content of (A) is 0.01 to 10% by weight, and the contents of (B) and (C) are each independently 0.001 to 30% by weight.

[In general formulas (1) and (2), ^R2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1.]
[2]
The conductive polymer aqueous solution according to the above [1], characterized in that the polystyrene sulfonic acid compound (B) is a polystyrene sulfonic acid compound (B) having an average molecular weight of 1,000 to 1,000,000.

[3]
The conductive polymer aqueous solution according to the above [1] or [2], characterized in that the polystyrene sulfonic acid compound (B) is polystyrene sulfonic acid which may have a substituent, a metal salt thereof, or an amine salt thereof, or a copolymer of a styrene sulfonic acid monomer which may have a substituent and another different monomer, a metal salt thereof, or an amine salt thereof.

[4]
The conductive polymer aqueous solution according to the above-mentioned [1], characterized in that the silane compound (C) is an alkoxysilane compound having at least one substituent selected from the group consisting of an epoxy group and an amino group.

[5]
A method for producing a film, comprising applying an aqueous solution of the conductive polymer according to any one of the above items [1] to [4] onto a support, and then drying the applied solution.

[6]
A film comprising a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2), a polystyrene sulfonic acid compound (B), and a silane compound (C):

[In general formulas (1) and (2), ^R2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1.]

The present invention provides a conductive polymer film that has excellent water resistance and heat resistance.

The present invention is described in detail below.

The conductive polymer aqueous solution of the present invention is an aqueous conductive polymer solution containing polythiophene (A) containing at least one structural unit selected from the group consisting of structural units represented by the following general formula (1) and structural units represented by the following general formula (2), a polystyrene sulfonic acid compound (B), and a silane compound (C), characterized in that the content of (A) is 0.01 to 10% by weight, and the contents of (B) and (C) are each independently 0.001 to 30% by weight.

[In general formulas (1) and (2), ^R2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1.]
In the above general formulas (1) and (2), R ² represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom.

The linear or branched alkyl group having 3 to 6 carbon atoms is not particularly limited, but examples thereof include n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, cyclopentyl, n-hexyl, 2-ethylbutyl, and cyclohexyl groups.

From the viewpoint of film-forming properties, ^R2 is preferably a hydrogen atom, a methyl group, an ethyl group, or a fluorine atom, and more preferably a hydrogen atom or a methyl group.

In the above general formulas (1) and (2), m represents an integer of 1 to 10, and from the viewpoint of film-forming properties, it is preferably an integer of 1 to 6, more preferably an integer of 1 to 4, and even more preferably 2 or 3.

In the above general formulas (1) and (2), n is 0 or 1, but from the viewpoint of film-forming properties, it is preferably 1.

The structural unit represented by the above general formula (2) represents the doped state of the structural unit represented by the above general formula (1).

Dopants that cause an insulator-metal transition by doping can be divided into acceptors and donors. The former enter close to the polymer chain of a conductive polymer and take away π electrons from the conjugated system of the main chain. As a result, a positive charge (hole) is injected into the main chain, so it is also called a p-type dopant. Conversely, the latter donates electrons to the conjugated system of the main chain, and these electrons move through the conjugated system of the main chain, so it is also called an n-type dopant.

The dopant in the present invention is a sulfo group or a sulfonate group that is covalently bonded within the polymer molecule, and is a p-type dopant. Polymers that exhibit conductivity without the addition of an external dopant are called self-doped polymers.

The polythiophene (A) may be a commercially available product or may be synthesized based on publicly known information. The synthesis method is not particularly limited, but may be, for example, a method in which a thiophene monomer represented by the following general formula (3) is polymerized in water or an alcohol solvent in the presence of an oxidizing agent, and then treated with an acid as necessary.

[In the above general formula (3), R ² , m, and n are defined the same as R ² , m, and n in the above general formulas (1) and (2). M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium ion.]
In the above general formula (3), M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium ion.

The alkali metal ion is not particularly limited, but examples thereof include lithium ion, potassium ion, sodium ion, rubidium ion, and cesium ion.

The organic ammonium ion is not particularly limited, but examples thereof include primary, secondary, or tertiary organic ammonium ions having a total carbon number of 1 to 30. More specifically, examples thereof include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, triethylammonium, normal-propylammonium, isopropylammonium, normal-butylammonium, hexylammonium, 2-hydroxyethylammonium, N,N-dimethyl-N-(2-hydroxyethyl)ammonium, and N-methyl-N-(2-hydroxyethyl)ammonium. Examples of the ammonium ion include ammonium, di(2-hydroxyethyl)ammonium, N-methyl-N,N-di(2-hydroxyethyl)ammonium, N,N,N-tri(2-hydroxyethyl)ammonium, 2,3-dihydroxypropylammonium, N-methyl-N-(2,3-dihydroxypropyl)ammonium, N,N-dimethyl-N-(2,3-dihydroxypropyl)ammonium, 1,4-butanediammonium, triisobutylammonium, triisopentylammonium, triisooctylammonium, pyridinium ion, picolinium ion, and lutidinium ion.

The quaternary ammonium ion is not particularly limited, but examples thereof include tetramethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, and tetra-n-hexylammonium ion.

For the polymer obtained after polymerization of the thiophene monomer represented by the general formula (3) (wherein M is not a hydrogen ion), M can be converted to a hydrogen ion by acid treatment. The polymerization method and the method for converting M to a hydrogen ion are not particularly limited, and any method described in a publicly known document can be selected and used. By the conversion to a hydrogen ion, a polythiophene (A) containing at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) can be produced.

The thiophene monomer represented by the above general formula (3) is not particularly limited, but specific examples thereof include sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propanesulfonate, potassium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, and 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate. -[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonic acid sodium salt, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propyl-1-propanesulfonic acid sodium salt, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonic acid sodium salt, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonic acid sodium salt 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopropyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isobutyl-1-propanesulfonate thorium, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopentyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-fluoro-1-propanesulfonate, potassium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, ]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid ammonium salt, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid triethylammonium salt, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butanesulfonic acid sodium salt , 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butanesulfonic acid potassium, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-butanesulfonic acid sodium, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-butanesulfonic acid potassium, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]- 1-Fluoro-1-butanesulfonic acid sodium salt, 4-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-fluoro-1-butanesulfonic acid potassium salt, 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonic acid, 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonic acid sodium salt, 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane Examples include lithium 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonate, potassium 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonate, 8-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)octane-1-sulfonic acid, sodium 8-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)octane-1-sulfonate, and potassium 8-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)octane-1-sulfonate.

In the present invention, the electrical conductivity of the polythiophene (A) is not particularly limited, but it is preferable that the electrical conductivity (electrical conductivity) in the film state is 10 S/cm or more.

In the conductive polymer aqueous solution of the present invention, the concentration of polythiophene (A) containing at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) is 0.01 to 10% by weight. In terms of excellent conductivity, the concentration of polythiophene (A) in the conductive polymer aqueous solution of the present invention is preferably 0.05% by weight or more, and in terms of excellent operability, it is preferably 8.0% by weight or less. In other words, it is preferably 0.05 to 8% by weight, more preferably 0.1 to 7% by weight, more preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight, and even more preferably 0.1 to 2% by weight.

In addition, the polythiophene (A) used in the present invention may be one synthesized based on publicly known information.

The polystyrene sulfonic acid compound (B) in the present invention may be a homopolymer (single polymer) in which styrene sulfonic acid, which may have a substituent, is used as a monomer, or a copolymer (copolymerization product), and may be an acid type compound or a salt compound. There is no particular restriction on the number or type of different monomers in the copolymer, and there is no particular restriction on the ratio of acid residues and salt residues.

The polystyrene sulfonic acid compound (B) in the present invention may be a commercially available product or may be produced by a generally known method.

The polystyrene sulfonic acid compound (B) used in the present invention is not particularly limited, but preferably has an average molecular weight in the range of 1,000 to 1,000,000, and more preferably has an average molecular weight in the range of 10,000 to 800,000.

The type of polystyrene sulfonic acid compound (B) used in the present invention is not particularly limited, but examples include polystyrene sulfonic acid which may have a substituent, its metal salt, or its amine salt, or a copolymer of a styrene sulfonic acid monomer which may have a substituent and another different monomer, its metal salt, or its amine salt.

The polystyrene sulfonic acid that may have the above-mentioned substituent is not particularly limited, but examples thereof include polystyrene sulfonic acid or polystyrene sulfonic acid having a substituent. In addition, examples of the above-mentioned substituent are not particularly limited, but examples thereof include a methyl group, an ethyl group, a methoxy group, an ethoxy group, a methoxymethyl group, a hydroxy group, a cyano group, a nitro group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an amino group, or a carboxy group.

The styrene sulfonic acid monomer that may have the above-mentioned substituent is not particularly limited, but examples thereof include styrene sulfonic acid or styrene sulfonic acid having a substituent. In addition, examples of the above-mentioned substituent are not particularly limited, but examples thereof include a methyl group, an ethyl group, a methoxy group, an ethoxy group, a methoxymethyl group, a hydroxy group, a cyano group, a nitro group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an amino group, or a carboxy group.

The other heteromonomers mentioned above are not particularly limited, but examples thereof include styrene which may have a substituent (e.g., styrene, p-fluorostyrene, p-methoxystyrene, p-butoxystyrene, or p-vinylbenzoic acid, etc.), acrylic acid which may have a substituent (e.g., acrylic acid, methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, or dimethylaminoethyl acrylate, etc.), methacrylic acid which may have a substituent (e.g., methacrylic acid, methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, or dimethylaminoethyl methacrylate, etc.), αβ-unsaturated carboxylic acid compounds (e.g., maleic anhydride, N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, etc.), or N-vinylpyrrolidone. Of these, styrene, p-butoxystyrene, or methyl methacrylate are preferred.

That is, the copolymer of the styrene sulfonic acid monomer which may have the above-mentioned substituent in the polystyrene sulfonic acid compound (B) and other different monomers is not particularly limited, but examples thereof include styrene sulfonic acid/styrene copolymer, styrene sulfonic acid/p-fluorostyrene copolymer, styrene sulfonic acid/p-methoxystyrene copolymer, styrene sulfonic acid/p-butoxystyrene copolymer, styrene sulfonic acid/p-vinylbenzoic acid copolymer, styrene sulfonic acid/acrylic acid copolymer, styrene sulfonic acid/methyl acrylate copolymer, styrene sulfonic acid/ethyl acrylate copolymer, styrene sulfonic acid/hydroxyethyl acrylate copolymer, styrene sulfonic acid/2-ethylhexyl acrylate copolymer, styrene sulfonic acid/dimethylaminoethyl acrylate copolymer, styrene sulfonic acid/methacrylic acid copolymer, styrene sulfonic acid/methyl methacrylate copolymer, styrene sulfonic acid/ethyl methacrylate copolymer, Examples of the copolymer include styrene sulfonic acid/hydroxyethyl methacrylate copolymer, styrene sulfonic acid/2-ethylhexyl methacrylate copolymer, styrene sulfonic acid/dimethylaminoethyl methacrylate copolymer, styrene sulfonic acid/maleic anhydride copolymer, styrene sulfonic acid/N-phenylmaleimide copolymer, styrene sulfonic acid/N-methylmaleimide copolymer, styrene sulfonic acid/N-ethylmaleimide copolymer, styrene sulfonic acid/N-butylmaleimide copolymer, styrene sulfonic acid/N-cyclohexylmaleimide copolymer, styrene sulfonic acid/N-benzylmaleimide copolymer, styrene sulfonic acid/N-vinylpyrrolidone copolymer, and styrene sulfonic acid/styrene/methyl methacrylate copolymer. Among these, styrene sulfonic acid/styrene copolymer, styrene sulfonic acid/p-butoxystyrene copolymer, and styrene sulfonic acid/methyl methacrylate copolymer are preferred. The copolymer may be a block copolymer, a random copolymer, or an alternating polymer.

The polystyrene sulfonic acid compound (B) of the present invention preferably contains polystyrene sulfonic acid, a metal salt thereof, or an amine salt thereof, or a styrene sulfonic acid copolymer selected from the group consisting of styrene sulfonic acid/styrene copolymer, styrene sulfonic acid/p-butoxystyrene copolymer, and styrene sulfonic acid/methyl methacrylate copolymer, a metal salt thereof, or an amine salt thereof, in terms of excellent film-forming properties.

The metal salt is not particularly limited, but examples thereof include sodium salts, potassium salts, and lithium salts. In addition, the amine in the amine salt is not particularly limited, but examples thereof include the same amine compounds in the conjugate acids of the amine compounds described below, and the same applies to preferred amine compounds.

The conductive polymer aqueous solution of the present invention contains 0.001 to 30% by weight of the polystyrene sulfonic acid compound (B), but in terms of excellent film adhesion, the content is preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight, and more preferably 0.1 to 1% by weight.

In addition, in terms of excellent pH stability of the conductive polymer aqueous solution of the present invention, the content of the polystyrene sulfonic acid compound (B) is preferably 10 parts by weight to 300 parts by weight, and more preferably 25 parts by weight to 200 parts by weight, per 100 parts by weight of the polythiophene (A).

The conductive polymer aqueous solution of the present invention is further characterized by containing 0.001 to 30% by weight of a silane compound (C).

The silane compound (C) is not particularly limited, but examples thereof include silane compounds having a chlorosilyl group, an acylsilyl group, an alkoxysilyl group, etc. (these compounds may have at least one substituent selected from the group consisting of a vinyl group, a methacryl group, a mercapto group, an epoxy group, and an amino group). In terms of ease of handling, silane compounds having an alkoxysilyl group (these compounds may have at least one substituent selected from the group consisting of a vinyl group, a methacryl group, a mercapto group, an epoxy group, and an amino group) are preferred, and in terms of reactivity, silane compounds having a methoxysilyl group or an ethoxysilyl group (these compounds may have at least one substituent selected from the group consisting of a vinyl group, a methacryl group, a mercapto group, an epoxy group, and an amino group) are particularly preferred.

Specific examples of the silane compound (C) include, but are not limited to, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxybutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, para-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyl Examples of such silane include pyrrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltrialkoxysilane, 3-isocyanatepropyltriethoxysilane, tris-(trimethoxysilylpropyl)triethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These may be used alone or in a mixture of two or more.

The silane compound (C) is preferably an alkoxysilane compound having at least one substituent selected from the group consisting of vinyl groups, methacryl groups, mercapto groups, epoxy groups, and amino groups, and more preferably an alkoxysilane compound having at least one substituent selected from the group consisting of epoxy groups and amino groups, and more preferably 3-glycidoxypropyltrimethoxysilane or 3-aminopropyltrimethoxysilane, in terms of excellent film-forming properties.

The conductive polymer aqueous solution of the present invention contains 0.001 to 30% by weight of the silane compound (C), but in terms of excellent film adhesion, the content is preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight, and more preferably 0.1 to 1% by weight.

In terms of excellent pH stability of the conductive polymer aqueous solution of the present invention, the content of the silane compound (C) is preferably 10 parts by weight to 300 parts by weight, and more preferably 25 parts by weight to 200 parts by weight, per 100 parts by weight of the polythiophene (A).

The conductive polymer aqueous solution of the present invention is characterized by containing the above-mentioned (A), (B), and (C), but may further contain another compound in addition to these. The other compound is not particularly limited, but examples thereof include at least one surfactant (D) selected from the group consisting of nonionic surfactants and amphoteric surfactants, at least one water-soluble compound (E) selected from the group consisting of alcohols and water-soluble resins, and/or a compound (F) capable of forming an ion pair with the sulfonic acid group of the polythiophene (A).

The nonionic surfactant is not particularly limited, but examples thereof include polyethylene glycol type surfactants, acetylene glycol type surfactants, polyhydric alcohol type surfactants, polymer type nonionic surfactants, etc.

The polyethylene glycol surfactant is not particularly limited, but examples thereof include higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher alkylamine ethylene oxide adducts, ethylene oxide adducts of fats and oils, and polypropylene glycol ethylene oxide adducts.

Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, Surfynol (registered trademark, manufactured by Air Products Co., Ltd.), and Olfine (registered trademark, manufactured by Nissin Chemical Industry Co., Ltd.).

The polyhydric alcohol surfactant is not particularly limited, but examples thereof include fatty acid esters of glycerol, fatty acid esters of pentaerythritol, fatty acid esters of sorbitol and sorbitan, fatty acid esters of sucrose, alkyl ethers of higher alcohols, and fatty acid amides of alkanolamines.

The polymeric nonionic surfactant is not particularly limited, but examples thereof include polyvinylpyrrolidone and copolymers of polyvinylpyrrolidone. The average molecular weight of the polyvinylpyrrolidone used in the present invention is 1,000 to 2,000,000, and preferably 10,000 to 1,500,000. The copolymer of polyvinylpyrrolidone is not particularly limited, but is preferably one having both hydrophilic and hydrophobic parts in the polymer chain, and examples thereof include copolymers in which polyvinylpyrrolidone is grafted to polyvinyl alcohol, [vinylpyrrolidone-vinyl acetate] block copolymers, [vinylpyrrolidone-methyl methacrylate] copolymers, [vinylpyrrolidone-normal butyl methacrylate] copolymers, and [vinylpyrrolidone-acrylamide] copolymers.

The amphoteric surfactant is not particularly limited, but examples thereof include betaine-type amphoteric surfactants, fluorine-based surfactants, and silicone-based surfactants.

The betaine-type amphoteric surfactant is not particularly limited, but examples thereof include alkyl dimethyl betaine, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.

The fluorosurfactant is not particularly limited as long as it has a perfluoroalkyl group, but examples include perfluoroalkanes, perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonic acids, and perfluoroalkyl ethylene oxide adducts.

The silicone surfactant is not particularly limited, but examples thereof include polyether-modified polydimethylsiloxane, polyetherester-modified polydimethylsiloxane, hydroxyl group-containing polyether-modified polydimethylsiloxane, acrylic group-containing polyether-modified polydimethylsiloxane, acrylic group-containing polyester-modified polydimethylsiloxane, perfluoropolyether-modified polydimethylsiloxane, perfluoropolyester-modified polydimethylsiloxane, and silicone-modified acrylic compounds.

Fluorosurfactants and silicone surfactants are effective as leveling agents to improve the flatness of coating films.

In the present invention, the surfactant (D) preferably has a solubility in water of 0.01% by weight or more and an HLB in the range of 7 to 20.

The Griffin method HLB (hydrophile-lipophile balance) is a number that indicates the hydrophilicity of a surfactant. The higher the value, the greater the hydrophilicity, and is expressed by the following formula:

Griffin HLB of nonionic surfactant = (molecular weight of hydrophilic group portion) / (molecular weight of surfactant) x 100/5 = (weight of hydrophilic group) / (weight of hydrophobic group + weight of hydrophilic group) x 100/5 = (weight % of hydrophilic group) / 5
In the present invention, the surfactant (D) is more preferably an acetylene glycol type surfactant or a polymer type surfactant.

The surfactant (D) may be added to the aqueous conductive polymer solution in the form of a solid, or may be added after being prepared as an aqueous solution in advance. In this case, the surfactant may be added to the aqueous conductive polymer solution alone, or two or more types may be mixed and added.

In the conductive polymer aqueous solution of the present invention, the content of at least one surfactant (D) selected from the group consisting of nonionic surfactants and amphoteric surfactants is preferably 0.001 to 10% by weight, and more preferably 0.1 to 5% by weight, in terms of excellent film-forming properties.

When the conductive polymer aqueous solution of the present invention contains a surfactant (D), the conductive polymer aqueous solution preferably contains 0.1 to 10% by weight of the polythiophene (A), 0.001 to 30% by weight of the polystyrene sulfonic acid compound (B), 0.001 to 30% by weight of the silane compound (C), and 0.001 to 10% by weight of the surfactant (D).

As described above, the conductive polymer aqueous solution of the present invention may contain at least one water-soluble compound (E) selected from the group consisting of alcohols and water-soluble resins.

The alcohol is not particularly limited, but may be, for example, at least one alcohol selected from the group consisting of monohydric alcohols, dihydric alcohols, trihydric alcohols, and sugar alcohols.

The monohydric alcohol is not particularly limited, but examples thereof include methanol, ethanol, 1-propanol, isopropanol, butanol, methoxyethanol, ethoxyethanol, butoxyethanol (butyl cellosolve), etc., with ethanol, butyl cellosolve, or hexyl cellosolve being preferred from the viewpoint of ease of handling. The dihydric alcohol is not particularly limited, but ethylene glycol is preferred from the viewpoint of availability. The trihydric alcohol is not particularly limited, but glycerol is preferred. The sugar alcohol is not particularly limited, but examples thereof include erythritol, sorbitol, arabitol, etc., and sorbitol is more preferred.

The water-soluble resin is preferably one that has substantially no surfactant action. Although not particularly limited, examples of the water-soluble resin are polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone (limited to those that have no surfactant action), poly(N-vinylacetamide), water-soluble polyester, water-soluble polyurethane, etc. From the viewpoint of reducing the amount of metal, it is preferable to use these water-soluble resins that have been subjected to a metal removal filter treatment using granular or membrane-like cation exchange resins, or zeta potential.

The molecular weight of the water-soluble resin is not particularly limited as long as it has good water solubility, but is preferably in the range of Mw = 1,000 to 2,000,000, more preferably 10,000 to 1,500,000, even more preferably Mw = 1,000 to 250,000, and even more preferably 1,000 to 100,000.

When the conductive polymer aqueous solution of the present invention contains a water-soluble compound (E), it preferably contains 0.001 to 30% by weight, and more preferably contains 0.01 to 25% by weight.

As described above, the conductive polymer aqueous solution of the present invention may further contain a compound (F) capable of forming an ion pair with the sulfonic acid group of the polythiophene (A) in terms of excellent film-forming properties. The compound (F) capable of forming an ion pair with the sulfonic acid group is not particularly limited, but examples thereof include alkali metal compounds, ammonia, organic amine compounds, and quaternary ammonium salts. These compounds can react with the sulfonic acid group of the polythiophene (A) to form alkali metal ion salts, ammonium ion salts, organic ammonium ion salts, and quaternary ammonium ion salts of the polythiophene (A), respectively.

The alkali metal compound is not particularly limited, but examples thereof include alkali metal salt compounds (e.g., lithium chloride, potassium chloride, sodium chloride, rubidium chloride, cesium chloride, lithium bromide, potassium bromide, sodium bromide, rubidium bromide, cesium bromide, etc.) or alkali metal hydroxides (e.g., lithium hydroxide, potassium hydroxide, sodium hydroxide, rubidium hydroxide, cesium hydroxide, etc.).

By adding the alkali metal compound to the conductive polymer aqueous solution of the present invention, the alkali metal ion salt of the lithiophene (A) can be prepared. The alkali metal ion is not particularly limited, but examples thereof include lithium ion, potassium ion, sodium ion, rubidium ion, and cesium ion.

The organic amine compound is not particularly limited, but examples thereof include primary, secondary, or tertiary organic amine compounds having a total carbon number of 1 to 30. More specifically, examples thereof include methylamine, dimethylamine, trimethylamine, ethylamine, triethylamine, normal-propylamine, isopropylamine, normal-butylamine, hexylamine, aminoethanol, dimethylaminoethanol, methylaminoethanol, diethanolamine, N-methyldiethanolamine, triethanolamine, 3-amino-1,2-propanediol, 3-methylamino-1,2-propanediol, 3-dimethylamino-1,2-propanediol, 1,4-butanediamine, triisobutylamine, triisopentylamine, triisooctylamine, imidazole, N-methylimidazole, 1,2-dimethylimidazole, pyridine, picoline, and lutidine.

By adding the organic amine compound to the conductive polymer aqueous solution of the present invention, the organic amine compound reacts with the polythiophene (A) to form an organic ammonium ion, and an organic ammonium ion salt of polythiophene (A) is prepared. The organic ammonium ion is not particularly limited, but examples thereof include primary, secondary, and tertiary organic ammonium ions having a total carbon number of 1 to 30. More specifically, examples of the organic ammonium ion include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, triethylammonium, normal-propylammonium, isopropylammonium, normal-butylammonium, hexylammonium, 2-hydroxyethylammonium, N,N-dimethyl-N-(2-hydroxyethyl)ammonium, N-methyl-N-(2-hydroxyethyl)ammonium, di(2-hydroxyethyl)ammonium, and the like. ammonium, N-methyl-N,N-di(2-hydroxyethyl)ammonium, N,N,N-tri(2-hydroxyethyl)ammonium, 2,3-dihydroxypropylammonium, N-methyl-N-(2,3-dihydroxypropyl)ammonium, N,N-dimethyl-N-(2,3-dihydroxypropyl)ammonium, 1,4-butanediammonium, triisobutylammonium, triisopentylammonium, triisooctylammonium, imidazole cation, N-methylimidazole cation, 1,2-dimethylimidazole cation, pyridinium ion, picolinium ion, or lutidinium ion.

The quaternary ammonium compound is not particularly limited, but examples thereof include tetramethylammonium chloride, tetraethylammonium chloride, tetra-n-propylammonium chloride, tetra-n-butylammonium chloride, and tetra-n-hexylammonium chloride.

By adding the quaternary ammonium compound to the conductive polymer aqueous solution of the present invention, the quaternary ammonium compound reacts with the polythiophene (A) to become a quaternary ammonium ion, and a quaternary ammonium ion salt of polythiophene (A) is prepared. The quaternary ammonium ion is not particularly limited, but examples thereof include tetramethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, and tetra-n-hexylammonium ion.

When the conductive polymer aqueous solution of the present invention contains the compound (E), the content of the compound (F) is preferably 0.001 to 20% by weight, and from the viewpoint of excellent film-forming properties, the content is preferably 0.01 to 15% by weight, and more preferably 0.1 to 10% by weight.

When the conductive polymer aqueous solution of the present invention contains the compound (F), a part or all of the polythiophene (A) containing at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) interacts with a part or all of the compound (F) to form a polythiophene (A) containing at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1') and the structural unit represented by the general formula (2'). That is, a mixture of the polythiophene (A) containing at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) and the compound (F) and the polythiophene (A) containing at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1') and the structural unit represented by the general formula (2') are the same thing.

[In the above general formula (1') and general formula (2'), the definitions and preferred ranges of R ² , m, and n are the same as those in the above general formula ( ¹ ) and general formula (2). M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium ion.]
The alkali metal ion, ammonium ion, organic ammonium ion, and quaternary ammonium ion in M are as described above.

The pH of the conductive polymer aqueous solution of the present invention is preferably 10 or less, and more preferably 9 or less. Furthermore, the pH of the conductive polymer aqueous solution of the present invention is preferably in the range of 1.5 to 9.5, and more preferably in the range of 1.5 to 9. Here, the procedure for adjusting the pH is not particularly limited, but an example of the method is a method of controlling the type and amount of the compound (F) added.

The method for preparing the conductive polymer aqueous solution of the present invention is not particularly limited, but may be, for example, a method in which at least the aqueous solution or solid of the polythiophene (A), the polystyrene sulfonic acid compound (B), the silane compound (C), and additional water as necessary are mixed in any order and by any method.

At this time, at least one surfactant (D) selected from the group consisting of the nonionic surfactants and amphoteric surfactants, at least one water-soluble compound (E) selected from the group consisting of the alcohols and water-soluble resins, and a compound (F) capable of forming an ion pair with the sulfonic acid group of the polythiophene (A) can each be mixed independently in any amount, in any order, and by any method into the aqueous conductive polymer solution of the present invention.

Here, the temperature during mixing is not particularly limited, but may be, for example, room temperature or heated. Preferably, the temperature is 0°C or higher and 100°C or lower.

The atmosphere in which the mixture is mixed is not particularly limited, but may be air or an inert gas.

When mixing the conductive polymer aqueous solution of the present invention, in addition to general mixing and dissolving operations using stirrer tips, stirring blades, etc., ultrasonic irradiation and homogenization treatment (for example, using a mechanical homogenizer, ultrasonic homogenizer, high-pressure homogenizer, etc.) may be performed. When homogenization treatment is performed, it is preferable to perform it at a low temperature to prevent thermal degradation of the polymer.

The concentration of the conductive polymer aqueous solution of the present invention may be adjusted by the blending ratio, or may be adjusted by concentrating after blending. The concentration method may be a method of distilling off the solvent under reduced pressure, or a method using an ultrafiltration membrane.

The concentration of polythiophene (A) in the conductive polymer aqueous solution of the present invention is not particularly limited as long as it is 0.001% by weight or more, but is preferably in the range of 0.01% by weight to 10% by weight. The conductive polymer aqueous solution of the present invention containing polythiophene (A), water-soluble polystyrene sulfonate compound (B), and silane compound (C) can be coated on a support and then dried and dehydrated to produce a conductive polymer film.

The particle size of the solid content in the conductive polymer aqueous solution of the present invention is not particularly limited, but the smaller the particle size, the better the water solubility, which is also desirable from the viewpoint of electrical conductivity and uniform film formation during film formation. For example, when the solid content concentration of the conductive polymer aqueous solution prepared at room temperature or under heating is 10% by weight or less, the water solubility is better if the particle size (D50) of the solid content is 0.02 μm or less.

The viscosity (20°C) of the conductive polymer aqueous solution of the present invention is a very important factor during production and use. The effects of high viscosity during production and use include loss during stirring and liquid transfer, and prolonged use. There are no particular limitations as long as it is 250 mPa·s or less, but it is preferably 100 mPa·s or less, and more preferably 50 mPa·s or less.

The method for forming a conductive polymer film from the conductive polymer aqueous solution of the present invention is not particularly limited, but for example, a method of applying the conductive polymer aqueous solution of the present invention to a support and drying it can be mentioned. By carrying out this method, a conductive polymer film can be easily obtained on a support (hereinafter, the support and the conductive polymer film are collectively referred to as a "coated article").

The support is not particularly limited as long as it can be coated with the conductive polymer aqueous solution of the present invention, and examples thereof include polymer substrates and inorganic substrates. Examples of the polymer substrates include thermoplastic resins, nonwoven fabrics, paper, and resist film substrates. Examples of the thermoplastic resins include polyethylene, polypropylene, polyethylene terephthalate, polyacrylate, and polycarbonate. The nonwoven fabrics may be made of, for example, natural fibers, synthetic fibers, or glass fibers. The paper may be one whose main component is general cellulose. Examples of the inorganic substrates include glass, ceramics, aluminum oxide, and tantalum oxide.

Examples of methods for applying the conductive polymer aqueous solution include casting, dipping, bar coating, dispenser, roll coating, gravure coating, flexographic printing, spray coating, spin coating, and inkjet printing. Spin coating is preferred.

The drying temperature for the coating is not particularly limited as long as it is a temperature at which a uniform conductive polymer film is obtained and is equal to or lower than the heat resistance temperature of the substrate, but is in the range of room temperature to 300°C, preferably in the range of room temperature to 250°C, and more preferably in the range of room temperature to 200°C.

The drying atmosphere may be air, an inert gas, a vacuum, or a reduced pressure. From the viewpoint of preventing deterioration of the polymer film, an inert gas such as nitrogen or argon is preferable.

The thickness of the resulting conductive polymer film is not particularly limited, but is preferably in the range of 10 ⁻³ to 10 ² μm, and more preferably 10 ⁻³ to 10 ⁻¹ μm.

The coated article of the present invention is used, for example, as an antistatic film or a solid electrolyte for a solid or hybrid electrolytic capacitor.

The following are examples of the present invention.

The analytical instruments and measurement methods used in this example are listed below.

[GC Measurement]
Apparatus: Shimadzu GC-2014.

[NMR Measurement]
Apparatus: Gemini-200, manufactured by VARIAN.

[Surface resistivity measurement]
Apparatus: Mitsubishi Chemical Loresta GP MCP-T600.

[Film thickness measurement]
Apparatus: DEKTAK XT manufactured by BRUKER.
[Viscosity measurement]
Complete type viscometer/BROOKFIELD VISCOMETER DV-1 Prime.

[conductivity]
Electrical conductivity [S/cm]=10 ⁴ /(Surface resistivity [Ω/□]×film thickness [μm]).

[Particle size measurement]
Apparatus: Microtrac Nanotrac UPA-UT151 manufactured by Nikkiso Co., Ltd.
[Measurement of Conductivity of Self-Doped Conductive Polymer (A)]
0.5 mL of an aqueous solution containing a self-doped conductive polymer was applied to a 25 mm square non-alkali glass plate, dried overnight at room temperature, and then heated on a hot plate at 120° C. for 20 minutes and then at 160° C. for 10 minutes to obtain a conductive polymer film. The conductivity was calculated from the film thickness and surface resistance.

[Conductivity measurement of conductive polymer film]
0.5 mL of the conductive polymer aqueous solution of the present invention was applied to a 25 mm square alkali-free glass plate, dried overnight at room temperature, and then heated on a hot plate at 150° C. for 30 minutes and then at 200° C. for 30 minutes to obtain a conductive polymer film. The conductivity was calculated from the film thickness and surface resistance value.

[Water resistance evaluation]
A conductive film prepared by the same procedure as in the measurement of the conductivity of the conductive polymer aqueous solution of the present invention was treated in a state of immersion in water at 80° C. for 60 minutes. A film in which the coating film was dissolved or which did not dissolve but fell off from the substrate was rated as poor, and a film in which the coating film was neither dissolved nor fallen off was rated as good.

[Heat resistance evaluation]
For a conductive film prepared by the same procedure as in the measurement of the conductivity of the conductive polymer aqueous solution of the present invention, the initial surface resistance (SR ₀ ) was measured using a Loresta GP MCP-T600 manufactured by Mitsubishi Chemical Corporation, and the conductive film was then left to stand at 150° C. for 60 hours in an EOP-450B (programmed constant temperature dryer) manufactured by ETTAS, after which the surface resistance (SR) was measured again. The rate of change (SR/SR ₀ ) of the surface resistance (SR) from the initial surface resistance (SR ₀ ) was calculated.

Synthesis example 1 (synthesis of sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate)

In a nitrogen atmosphere, 0.437 g (10.9 mmol) of 60% sodium hydride and 37 mL of toluene were charged into a 100 mL eggplant-shaped flask, followed by the addition of 1.52 g (8.84 ml) of (2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methanol. The mixture was then heated to reflux temperature while stirring, and stirred at this reflux temperature for 1 hour. Then, while continuing the reflux, a mixture consisting of 1.21 g (8.89 mmol) of 2,4-butanesultone and 10 mL of toluene was added dropwise, and then stirred at the reflux temperature for another 2 hours. After cooling, the resulting reaction liquid was added dropwise to 160 mL of acetone to cause reprecipitation. The resulting powder was filtered and vacuum dried to obtain 1.82 g of pale yellow powder with a yield of 62%.

NMR measurements confirmed that this was sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, as shown in formula (6) above.

^1H -NMR ( _D2 O) δ (ppm); 6.67 (s, 2H), 4.54-4.60 (m, 1H), 4.45 (dd, 1H, J = 12.0, 2.2Hz), 4.26 (dd, 1H, J = 12.0, 6 .8Hz), 3.90-3.81 (m, 4H), 3.10-3.18 (m, 1H), 2.30-2.47 (m, 1H), 1.77-1.92 (m, 1H), 1.45 (d, 3H).

¹³ C-NMR (D ₂ O) δ (ppm); 14.91, 31.22, 53.13, 66.18, 69.18, 73.29, 73.36, 100.81, 100.94, 140.88, 141.06.

Synthesis Example 2: Synthesis of polythiophene (A) [polymer containing structural units represented by the following formulas (7) and (8)].

10 g (30 mmol) of sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate synthesized according to Synthesis Example 1 and 150 g of water were added to a 500 ml separable flask. After dissolution, 2.94 g (18.1 mmol) of anhydrous iron(III) chloride was added at room temperature and stirred for 20 minutes. Then, a mixed solution consisting of 14.5 g (60.4 mmol) of sodium persulfate and 100 g of water was added dropwise while maintaining the reaction solution temperature at 30°C or less. Next, after stirring at room temperature for 3 hours, the reaction solution was dropped into 800 g of acetone to precipitate a black Na-type polymer. The polymer was filtered and dried under vacuum to obtain 18.0 g of crude polymer of sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate.

Next, 14.5 g of this crude polymer was mixed with water to prepare a 2 wt% solids aqueous solution, and 700 g of the resulting 725 g solution was passed through a column packed with 200 mL of cation exchange resin Lewatit MonoPlus S100 (H type) (space velocity = 1.1) to obtain 738 g of an H type polymer aqueous solution. This polymer aqueous solution was then purified by cross-flow ultrafiltration (filter = Vivaflow 200, molecular weight cutoff = 5,000, permeability = 5) to obtain 698 g of a deep ultramarine aqueous solution of a polymer containing structural units represented by the above formulas (7) and (8). The amount of polymer (solid content) contained in the polymer aqueous solution was 0.74 wt %. In addition, when ICP-MS analysis was performed, the polymer aqueous solution contained 44 ppm of iron ions and 12 ppm of sodium ions based on the solid content.

Example 1.
20.67 g of a conductive polymer aqueous solution containing 1.2 wt % of polythiophene (A) obtained by a method conforming to Synthesis Example 2 was mixed with 3.47 g of polystyrene sulfonic acid (B) [manufactured by Aldrich/Mw=75,000, 18 wt % aqueous solution], 0.50 g of 3-glycidoxypropyltrimethoxysilane (C), 0.25 g of ethylene glycol as a water-soluble compound (E), and 0.12 g of water, and the mixture was thoroughly stirred to obtain a conductive polymer aqueous solution having a solid content concentration of 5.5 wt %. The conductivity of the film prepared from this conductive polymer aqueous solution was 20 S/cm, and in the water resistance test, the conductive film did not dissolve in water or fall off from the substrate, showing good water resistance. In addition, the SR/SR ₀ after the heat resistance test was stable at 1.0, showing good heat resistance.

Example 2.
16.67 g of a conductive polymer aqueous solution containing 1.5 wt % of polythiophene (A) obtained by a method conforming to Synthesis Example 2 was mixed with 0.69 g of polystyrene sulfonic acid (B) [manufactured by Aldrich/Mw=75,000, 18 wt % aqueous solution], 0.05 g of 3-glycidoxypropyltrimethoxysilane (C), 5.00 g of ethylene glycol as a water-soluble compound (E), and 2.59 g of water, and the mixture was thoroughly stirred to obtain a conductive polymer aqueous solution having a solid content concentration of 1.7 wt %. The conductivity of the film prepared from this conductive polymer aqueous solution was 182 S/cm, and in the water resistance test, the conductive film did not dissolve in water or fall off from the substrate, showing good water resistance. In addition, the SR/SR ₀ after the heat resistance test was stable at 1.1, showing good heat resistance.

Example 3.
The same procedure as in Example 1 was repeated except that 3-glycidoxypropyltrimethoxysilane (C) was used instead of 3-glycidoxybutyltrimethoxysilane (C). The electrical conductivity of the film prepared from this conductive polymer aqueous solution was 18 S/cm, and in the water resistance test, the conductive film did not dissolve in water or fall off from the substrate, showing good water resistance. In addition, the SR/SR ₀ after the heat resistance test was stable at 1.0, showing good heat resistance.

Example 4.
The same procedure as in Example 2 was repeated except that 3-glycidoxypropyltrimethoxysilane (C) was used instead of 3-aminopropyltrimethoxysilane (C). The electrical conductivity of the film prepared from this conductive polymer aqueous solution was 156 S/cm, and in the water resistance test, the conductive film did not dissolve in water or fall off from the substrate, showing good water resistance. In addition, the SR/SR ₀ after the heat resistance test was stable at 1.0, showing good heat resistance.

Comparative Example 1.
An experiment was carried out in accordance with the method of Example 1, except that 3.97 g of water was used instead of 3.47 g of polystyrene sulfonic acid (B) [manufactured by Aldrich/Mw=75,000, 18 wt % aqueous solution] and 0.50 g of 3-glycidoxypropyltrimethoxysilane (C) in Example 1. The conductive film produced from this conductive polymer aqueous solution was not dissolved in the water resistance test, but detachment of the coating film from the substrate was observed, and therefore it was judged to be defective.

Comparative Example 2.
An experiment was carried out in accordance with the method of Example 1, except that 0.5 g of water was used instead of 0.50 g of 3-glycidoxypropyltrimethoxysilane (C). The conductive film made from this conductive polymer aqueous solution was not dissolved in the water resistance test, but detachment of the coating film from the substrate was observed, and therefore it was determined to be defective.

Comparative Example 3.
The same procedure as in Example 1 was repeated except that polythiophene (A) was changed to commercially available PEDOT:PSS (aqueous solution with a concentration of 1.2 wt %, manufactured by Aldrich Co.) The conductive film made from this aqueous conductive polymer solution had good water resistance, but the electrical conductivity was only 0.5 S/cm, and the SR/SR ₀ after the heat resistance test was 3.4, which was a larger change than that of the conductive film of the present invention.

The coatings made from these conductive polymer aqueous solutions have the unexpected advantage of being water-resistant and heat-resistant while maintaining electrical conductivity.

The conductive polymer film produced using the conductive polymer aqueous solution of the present invention has the unexpected and exceptional effect of being superior in heat resistance and water resistance and capable of maintaining high conductivity compared to those produced using conventionally known conductive polymer aqueous solutions.

The conductive polymer film and coated article formed from the conductive polymer aqueous solution of the present invention have high conductivity, and are therefore expected to be used as an antistatic film and a solid electrolyte in solid electrolytic capacitors.

The conductive polymer aqueous solution of the present invention is a conductive polymer aqueous solution that has excellent adhesion to substrates such as polymers, metals, and glass. Furthermore, since the conductive polymer aqueous solution forms a good conductive polymer film, it can be used as a conductive coating agent (antistatic agent) and a solid electrolyte (cathode material) for solid or hybrid electrolytic capacitors. In particular, it has excellent adhesion between the dielectric and conductive layer, water resistance, and heat resistance, which are issues in tantalum and aluminum solid electrolytic capacitors, so that a capacitor with high durability and high reliability can be provided. In addition, a coated article made of a polymer substrate coated with this conductive polymer film can be used as an antistatic film and a separator for a wound aluminum electrolytic capacitor. In addition, it is expected to be applied to electrochromic elements, transparent electrodes, transparent conductive films, thermoelectric conversion materials, chemical sensors, actuators, electromagnetic wave shielding materials, and hole transport materials used in organic EL and solar cell applications.

Claims (6)

A conductive polymer aqueous solution containing a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), a polystyrene sulfonic acid compound (B), and a silane compound (C), wherein the content of (A) is 0.01 to 10% by weight, and the contents of (B) and (C) are each independently 0.001 to 30% by weight (excluding a conductive polymer aqueous solution containing a poly(3,4-ethylenedioxythiophene derivative) represented by the following general formula (3a) :

[In general formulas (1) and (2), ^R2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1.]

[In general formula (3a), R3 ^represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a substituted alkoxy group having 1 to 6 carbon atoms.] The conductive polymer aqueous solution according to claim 1, characterized in that the polystyrene sulfonic acid compound (B) is a polystyrene sulfonic acid compound (B) having an average molecular weight of 1,000 to 1,000,000. The conductive polymer aqueous solution according to claim 1 or 2, characterized in that the polystyrene sulfonic acid compound (B) is polystyrene sulfonic acid which may have a substituent, a metal salt thereof, or an amine salt thereof, or a copolymer of a styrene sulfonic acid monomer which may have a substituent and another different monomer, a metal salt thereof, or an amine salt thereof. The conductive polymer aqueous solution according to claim 1, characterized in that the silane compound (C) is an alkoxysilane compound having at least one substituent selected from the group consisting of an epoxy group and an amino group. A method for producing a film, comprising applying an aqueous solution of a conductive polymer according to any one of claims 1 to 4 onto a support and then drying the applied solution. A film comprising a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2), a polystyrene sulfonic acid compound (B), and a silane compound (C) (excluding a film containing a poly(3,4-ethylenedioxythiophene derivative) represented by the following general formula (3a)) .

[In general formulas (1) and (2), ^R2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1.]

[In general formula (3a), R3 ^represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a substituted alkoxy group having 1 to 6 carbon atoms.]