JP7770513B2 - Method for producing conductive polymer dispersion and method for producing conductive film - Google Patents

Description

The present invention relates to a conductive polymer dispersion containing a π-conjugated conductive polymer and a method for producing the same, a paint, and a conductive film and a method for producing the same.

Conductive polymer dispersions containing conductive complexes in which a π-conjugated conductive polymer is doped with a polyanion are sometimes used as paints for forming conductive layers. For example, the π-conjugated conductive polymer poly(3,4-ethylenedioxythiophene) is difficult to disperse in water, but doping it with polystyrene sulfonic acid to form PEDOT-PSS increases its dispersibility in water. Patent Document 1 discloses a technique for improving the hydrophilicity of a conductive complex and its reactivity with epoxy compounds by dispersing the conductive complex in water and leaving it for 180 days or more.

Japanese Patent Application Laid-Open No. 2020-31013

In the method of Patent Document 1, a conductive composite is reacted with an epoxy compound, and then dissolved in an organic solvent to form a coating material, thereby improving the wettability of the composite to a hydrophobic film substrate. When the conductive composite is not hydrophobized by reaction with an epoxy compound, a water-soluble organic solvent such as alcohol is typically added to the conductive polymer dispersion to improve the wettability of the composite to the film substrate. However, the dispersion stability of the conductive composite in a coating material containing a water-soluble organic solvent is not necessarily high, and dispersibility may decrease within several tens of hours after the addition of the water-soluble organic solvent. The conductivity of the conductive layer formed by applying a coating material with reduced dispersibility also decreases.
For this reason, after a paint is obtained by adding a water-soluble organic solvent to a conductive polymer dispersion that has been subjected to a dispersion treatment, it is required to maintain the dispersibility of the conductive composite in the paint.

The inventors therefore conducted extensive research into a method for obtaining a conductive polymer dispersion with improved dispersibility of the conductive complex by devising a dispersion treatment at the conductive polymer dispersion stage before preparing the paint, and a method for producing a conductive polymer dispersion in which the decrease in dispersibility of the conductive complex over time is suppressed even after adding a water-soluble organic solvent to form a paint, and have completed the present invention.

The present invention provides a conductive polymer dispersion with improved stability after dispersion treatment, and a method for producing the same. It also provides a paint containing the conductive polymer dispersion, and a conductive film using the conductive polymer dispersion or the paint, and a method for producing the same.

[1] A conductive polymer dispersion comprising a conductive complex containing a π-conjugated conductive polymer and a polyanion, and water, wherein the mass ratio of the π-conjugated conductive polymer to the polyanion is from (1:2) to (1:5), and the weight-average molecular weight Mw of the polyanion is from 200,000 to 1,000,000, and wherein the viscosity at 25°C is from 35 cP to 45 cP when the concentration of the conductive complex relative to the total mass of the conductive polymer dispersion is adjusted to 1.3 mass%.
[2] The conductive polymer dispersion according to [1], wherein the particle size at 25°C when the concentration of the conductive complex is adjusted to 0.13 mass% is less than 500 nm.
[3] The conductive polymer dispersion according to [1] or [2], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrenesulfonic acid.
[4] A coating material comprising the conductive polymer dispersion liquid according to any one of [1] to [3] and a water-soluble organic solvent.
[5] The paint according to [4], wherein the water-soluble organic solvent contains at least one of methanol and isopropanol.
[6] A method for producing a conductive polymer dispersion, comprising: polymerizing a monomer that forms a π-conjugated conductive polymer in a reaction liquid containing the monomer, a polyanion, and water, to obtain a conductive polymer dispersion containing a conductive complex containing the π-conjugated conductive polymer and the polyanion, and water; and then dispersing the conductive polymer dispersion, wherein, in the dispersion treatment, the conductive complex is dispersed so that the viscosity at 25°C is 35 cP or more and 45 cP or less when the concentration of the conductive complex is adjusted to 1.3 mass % relative to the total mass of the obtained conductive polymer dispersion.
[7] The method for producing a conductive polymer dispersion according to [6], wherein the liquid temperature of the conductive polymer dispersion is adjusted to 14° C. or higher and 25° C. or lower during the dispersion treatment.
[8] The method for producing a conductive polymer dispersion according to [6] or [7], wherein the conductive polymer dispersion before the dispersion treatment is held in a first container adjusted to 14°C or higher and 25°C or lower, the conductive polymer dispersion is gradually introduced from the first container into a disperser main body to perform the dispersion treatment, and the conductive polymer dispersion after the dispersion treatment is sequentially discharged from the disperser main body to a second container adjusted to 14°C or higher and 25°C or lower, and collected.
[9] A method for producing a conductive film, comprising applying the conductive polymer dispersion according to any one of [1] to [3] or the coating material according to [4] or [5] to at least one surface of a film substrate.
[10] A conductive film comprising a conductive layer formed on at least one surface of a film substrate, the conductive polymer dispersion according to any one of [1] to [3], or a cured layer of the coating material according to [4] or [5].

In the conductive polymer dispersion of the present invention, the viscosity measured under predetermined conditions falls within a specific range, thereby improving dispersion stability.
According to the method for producing a conductive polymer dispersion of the present invention, a conductive polymer dispersion having improved dispersion stability as described above can be easily produced.
According to the coating material of the present invention, the dispersion stability of the conductive complex is improved, so that a conductive layer having good conductivity can be formed even after the coating material is prepared and left to stand for one day or more.
According to the method for producing a conductive film of the present invention, a conductive film having a conductive layer with good conductivity can be easily formed.

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

In this specification and claims, the lower and upper limits of numerical ranges indicated with "~" are considered to be included in the numerical range.

<<Conductive polymer dispersion>>
A first aspect of the present invention is a conductive polymer dispersion comprising a conductive complex containing a π-conjugated conductive polymer and a polyanion, and water, wherein the mass ratio of the π-conjugated conductive polymer to the polyanion is from (1:2) to (1:5), and the weight-average molecular weight Mw of the polyanion is from 200,000 to 1,000,000, and the conductive polymer dispersion has a viscosity of from 35 cP to 45 cP at 25°C when the concentration of the conductive complex is adjusted to 1.3 mass%.

<π-conjugated conductive polymer>
The π-conjugated conductive polymer is not particularly limited as long as it has the effects of the present invention and is an organic polymer whose main chain is composed of a π-conjugated system, and examples thereof include polypyrrole-based conductive polymers, polythiophene-based conductive polymers, polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylene vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene vinylene-based conductive polymers, and copolymers thereof. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferred, and from the viewpoint of transparency, polythiophene-based conductive polymers are more preferred.

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-iodothiophene). thiophene), 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 oxythiophene), 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 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 the above π-conjugated conductive polymers, poly(3,4-ethylenedioxythiophene) is particularly preferred from the viewpoints of conductivity, transparency, and heat resistance.
The conductive composite may contain one type of π-conjugated conductive polymer, or two or more types of polymers.

<Polyanion>
A polyanion is a polymer having two or more monomer units each having an anionic group in the molecule. The anionic group of this polyanion functions as a dopant for a π-conjugated conductive polymer, improving the conductivity of the π-conjugated conductive polymer.
The anionic group of the polyanion is preferably a sulfo group or a carboxy group.
Specific examples of such polyanions include polymers having a sulfo group, such as polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic acid esters having a sulfo group, polymethacrylic acid esters having a sulfo group (for example, poly(4-sulfobutyl methacrylate, polysulfoethyl methacrylate, polymethacryloyloxybenzenesulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), and polyisoprene sulfonic acid; and polymers having a carboxy group, such as polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropanecarboxylic acid), and polyisoprene carboxylic acid. These may be homopolymers or copolymers of two or more types.
Among these polyanions, polymers having sulfo groups are preferred, and polystyrene sulfonic acid is more preferred, since they can further increase the conductivity.
The conductive complex may be made up of one type of polyanion or two or more types of polyanions.

The weight-average molecular weight Mw of the polyanion is from 200,000 to 1,000,000, preferably from 300,000 to 1,000,000, more preferably from 400,000 to 1,000,000, even more preferably from 500,000 to 1,000,000, still more preferably from 600,000 to 1,000,000, even more preferably from 700,000 to 1,000,000, particularly preferably from 800,000 to 1,000,000, and most preferably from 900,000 to 1,000,000. Here, the weight-average molecular weight Mw is the average molecular weight on a mass basis (which may also be referred to as the mass-average molecular weight) measured using gel permeation chromatography and pullulan of a known weight-average molecular weight as a standard substance.
When the weight average molecular weight Mw is within the above preferred range, the dispersion stability of the conductive composite in the conductive polymer dispersion of this embodiment and in the coating material of the second embodiment described below is further improved.

A conductive composite is formed by doping a π-conjugated conductive polymer with a polyanion. However, in the polyanion, some anionic groups do not dope into the π-conjugated conductive polymer, leaving excess anionic groups that are not involved in the doping. Because these excess anionic groups are hydrophilic, the conductive composite has high water dispersibility but low organic solvent dispersibility.
When the number of all anionic groups in the polyanion is taken as 100 mol %, the excess anionic groups are preferably 30 mol % or more and 90 mol % or less, and more preferably 45 mol % or more and 75 mol % or less.

The content ratio of the π-conjugated conductive polymer to the polyanion in the conductive composite is (1:2) to (1:5) on a mass basis, preferably (1:2) to (1:4.5), more preferably (1:2) to (1:4), and even more preferably (1:2) to (1:3).
When the content is at least the lower limit of the above range, the doping effect of the polyanion is sufficiently exhibited, and the dispersion stability of the conductive composite is further improved.
When the content is equal to or less than the upper limit of the above range, a conductive layer with excellent conductivity can be formed.

The content of the conductive complex relative to the total mass of the conductive polymer dispersion of this embodiment is, for example, preferably 0.1 mass % or more and 20 mass % or less, more preferably 0.2 mass % or more and 10 mass % or less, even more preferably 0.3 mass % or more and 10.0 mass % or less, and particularly preferably 1.0 mass % or more and 5.0 mass % or less.
When the content is within the above range, the dispersion stability of the conductive composite is further improved.

The viscosity of the conductive polymer dispersion of this embodiment at 25° C. is 35 cP or more and 45 cP or less when the concentration of the conductive complex relative to the total mass of the conductive polymer dispersion is adjusted to 1.3 mass %.
When measuring the viscosity, the conductive polymer dispersion preferably contains only ion-exchanged water as a dispersion medium, and preferably contains no additives other than the conductive composite.
The viscosity is measured at 25°C using a tuning fork vibration viscometer in accordance with JIS Z8803:2011 (viscosity measurement method using a vibration viscometer).
The viscosity range is preferably 35 to 45 cP, more preferably 38 to 42 cP. Within these preferred ranges, the dispersion stability of the conductive composite is further improved.

The particle size of the conductive polymer dispersion of this embodiment at 25° C. is preferably less than 500 nm, more preferably 300 nm to 480 nm, more preferably 350 nm to 460 nm, and even more preferably 380 nm to 440 nm, when the concentration of the conductive composite relative to the total mass of the conductive polymer dispersion is adjusted to 0.13 mass %. Within these preferred ranges, the dispersion stability of the conductive composite is further improved.
When measuring the particle size, the conductive polymer dispersion preferably contains only ion-exchanged water as a dispersion medium, and preferably does not contain any additives other than the conductive composite.
The particle size is determined as a value obtained by measuring the cumulant average particle size by dynamic light scattering.

≪Paint≫
A second aspect of the present invention is a paint comprising the conductive polymer dispersion of the first aspect and a water-soluble organic solvent. In the paint of this aspect, the conductive complex is in a dispersed state.

The paint of this embodiment contains water and a water-soluble organic solvent. The mixture of water and a water-soluble organic solvent is sometimes called an aqueous dispersion medium.

The water-soluble organic solvent is an organic solvent that dissolves in an amount of 1 g or more in 100 g of water at 20°C.
Examples of the water-soluble organic solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, nitrogen atom-containing solvents, and ester-based solvents.
Examples of alcohol-based solvents include methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 2-methyl-2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, allyl alcohol, ethylene glycol, propylene glycol, propylene glycol monomethyl ether, and ethylene glycol monomethyl ether.
Examples of the ether solvent include diethyl ether, dimethyl ether, propylene glycol dialkyl ether, and diethylene glycol diethyl ether.
Examples of ketone solvents include diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisopropyl ketone, methyl ethyl ketone, acetone, and diacetone alcohol.
Examples of nitrogen atom-containing solvents include N-methylpyrrolidone, dimethylacetamide, and dimethylformamide.
The water-soluble organic solvent may be contained alone or in combination of two or more kinds.
The water-soluble organic solvent is preferably an alcohol-based solvent or a ketone-based solvent, more preferably an alcohol-based solvent, because the coating material of this embodiment has good coatability on the film substrate.

The content of the water-soluble organic solvent relative to the total mass of the aqueous dispersion medium is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The content of the water-soluble organic solvent is preferably 90% by mass or less.
Within the above preferred range, the wettability of the conductive composite to the film substrate can be improved while suppressing deterioration over time in the dispersion stability of the conductive composite in the coating material of this embodiment.

The content of water relative to the total mass of the aqueous dispersion medium is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass or less, and even more preferably 25% by mass or more and 35% by mass or less.
Within the above preferred range, the wettability of the conductive composite to the film substrate can be improved while suppressing deterioration over time in the dispersion stability of the conductive composite in the coating material of this embodiment.

The content of the conductive complex relative to the total mass of the paint of this embodiment is, for example, preferably 0.001 mass% or more and 1 mass% or less, more preferably 0.005 mass% or more and 0.2 mass% or less, even more preferably 0.01 mass% or more and 0.1 mass% or less, and particularly preferably 0.03 mass% or more and 0.05 mass% or less.
When the content is within the above preferred range, it is possible to prevent a decrease in the dispersion stability of the conductive composite in the coating material of this embodiment, and it is possible to form a conductive layer with good conductivity by applying it to a film substrate.

<Binder components>
The coating material of this embodiment may contain a binder component. The binder component is a resin other than the π-conjugated conductive polymer and the polyanion or a precursor thereof, and is a thermoplastic resin or a curable monomer or oligomer that is cured when the conductive layer is formed. The thermoplastic resin becomes the binder resin as it is, and the curable monomer or oligomer becomes the resin formed by curing.
The binder component may be one kind or two or more kinds.

Specific examples of binder resins derived from binder components include acrylic resins (acrylic compounds), polyester resins, polyurethane resins, polyimide resins, polyether resins, melamine resins, and silicones.
The binder resin contained in the coating material of this embodiment is preferably a water-dispersible resin, more preferably a water-dispersible emulsion resin. The water-dispersible resin is an emulsion resin or a water-soluble resin.

Specific examples of water-dispersible emulsion resins include acrylic resins (acrylic compounds), polyester resins, polyurethane resins, polyimide resins, and melamine resins, which are emulsified with an emulsifier. Of these, polyester emulsions are preferred because they increase the strength of the coating film formed when the coating material of this embodiment is applied to a film substrate. In particular, when applied to a polyester film substrate, polyester emulsions are preferred because they increase the adhesion of the coating film to the film substrate.

Specific examples of water-soluble resins include acrylic resins (acrylic compounds), polyester resins, polyurethane resins, polyimide resins, and melamine resins, which have acid groups such as carboxyl groups or sulfo groups, or their salts. Here, the water-soluble resin should be one that dissolves in 100 g of distilled water at 25°C in an amount of 1 g or more, preferably 5 g or more, and more preferably 10 g or more.

The acid groups, such as carboxyl groups and sulfo groups, contained in the water-dispersible resin may form salts with cations, such as sodium ions and potassium ions.

The curable monomer or oligomer may be a thermosetting monomer or oligomer, or a photocurable monomer or oligomer. Here, the oligomer refers to a polymer having a mass average molecular weight of less than 10,000. Note that a polymer having a mass average molecular weight of more than 10,000 does not have curability.
Examples of the curable monomer include an acrylic monomer (acrylic compound), an epoxy monomer, and an organosiloxane. Examples of the curable oligomer include an acrylic oligomer (acrylic compound), an epoxy oligomer, and a silicone oligomer (curable silicone).
When an acrylic monomer or an acrylic oligomer is used as the binder component, it can be easily cured by heating or light irradiation. When an organosiloxane or a silicone oligomer is used as the binder component, it can impart releasability (non-stickiness) to the conductive layer.

When a curable monomer or oligomer is included, it is preferable to further include a curing catalyst. For example, when a thermosetting monomer or oligomer is included, it is preferable to include a thermal polymerization initiator that generates radicals upon heating, and when a photocurable monomer or oligomer is included, it is preferable to include a photopolymerization initiator that generates radicals upon light irradiation. Furthermore, when an organosiloxane or silicone oligomer is included, it is preferable to include a platinum catalyst for curing.

The content of the binder component in the coating material of this embodiment is preferably 100 parts by mass or more and 20,000 parts by mass or less, and more preferably 100 parts by mass or more and 5,000 parts by mass or less, relative to 100 parts by mass of the conductive composite.
When the content is equal to or greater than the lower limit of the above range, the film-forming properties and film strength can be improved when the coating material of this embodiment is applied to a film substrate.
When the content is equal to or less than the upper limit of the above range, it is possible to suppress a decrease in conductivity due to a decrease in the content ratio of the conductive composite.

(Other additives)
The coating material of this embodiment may contain other known additives.
Examples of additives that can be used include surfactants, inorganic conductive agents, antifoaming agents, coupling agents, antioxidants, and ultraviolet absorbers.
The surfactant may be a nonionic, anionic, or cationic surfactant, with the nonionic surfactant being preferred from the standpoint of storage stability. A polymer surfactant such as polyvinylpyrrolidone may also be added.
Examples of inorganic conductive agents include metal ions, conductive carbon, etc. Metal ions can be generated by dissolving a metal salt in water.
Examples of the antifoaming agent include silicone resin, polydimethylsiloxane, and silicone oil.
The coupling agent may be a silane coupling agent having a vinyl group or an amino group.
Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, oxanilide-based ultraviolet absorbers, hindered amine-based ultraviolet absorbers, and benzoate-based ultraviolet absorbers.
When the coating material of this embodiment contains the above-mentioned additive, the content ratio thereof is determined appropriately depending on the type of additive, but can be, for example, in the range of 0.001 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the conductive composite.

The coating material of this embodiment can be produced by adding water, a water-soluble organic solvent, a binder component, other additives, etc. to the conductive polymer dispersion of the first embodiment as appropriate and mixing them in a conventional manner.

<Method for producing conductive polymer dispersion>
A third aspect of the present invention is a method for producing a conductive polymer dispersion, the method comprising: polymerizing a monomer that forms a π-conjugated conductive polymer in a reaction liquid containing the monomer, a polyanion, and water, to obtain a conductive polymer dispersion containing a conductive complex that contains the π-conjugated conductive polymer and the polyanion, and then dispersing the conductive polymer dispersion; wherein, in the dispersion treatment, the conductive complex is dispersed so that the viscosity at 25°C is 35 cP or more and 45 cP or less when the concentration of the conductive complex is adjusted to 1.3 mass % relative to the total mass of the obtained conductive polymer dispersion.

An aqueous solution (the reaction solution) containing the monomer and the polyanion at a specific content ratio is prepared, and the monomer is polymerized to form a π-conjugated conductive polymer. In the reaction solution, the π-conjugated conductive polymer is naturally doped with the polyanion, forming a conductive complex consisting of the π-conjugated conductive polymer and the polyanion. The content ratio (by mass) of the π-conjugated conductive polymer to the polyanion contained in the formed conductive complex is the same as the ratio of the content of the monomer to the content of the polyanion contained in the aqueous solution immediately before the start of polymerization. In other words, the content ratio of the monomer to the polyanion added to the reaction solution is reflected in the content ratio of the π-conjugated conductive polymer to the polyanion in the formed conductive complex.

The content ratio of the monomer to the polyanion in the reaction solution immediately before the start of polymerization is (1:2) to (1:5) by mass, preferably (1:2) to (1:4.5), more preferably (1:2) to (1:4), and even more preferably (1:2) to (1:3).
When the content is within the above range, the conductive polymer dispersion liquid of the first embodiment described above can be easily formed.

A catalyst may be added to the reaction solution. The catalyst is not particularly limited as long as it polymerizes the monomer, and examples thereof include transition metal compounds such as ferric chloride, ferric sulfate, ferric nitrate, and cupric chloride. Among these, it is preferable to use a catalyst containing iron, as this allows the polymerization of the monomer to proceed stably at room temperature.
It is preferable to contain an oxidizing agent together with the catalyst. The oxidizing agent can return the reduced catalyst to its original oxidized state. Examples of the oxidizing agent include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate.

The content of the monomer contained in the reaction liquid immediately before the start of polymerization is, for example, preferably 0.1 mass % or more and 20 mass % or less, more preferably 0.2 mass % or more and 10 mass % or less, and even more preferably 0.3 mass % or more and 5 mass % or less, relative to the total mass of the reaction liquid.
Within the above range, the polymerization reaction can proceed stably, and therefore the complexation with the polyanion present in the reaction system proceeds stably, making it possible to easily obtain a conductive complex with good conductivity.

The content of the catalyst in the reaction liquid immediately before the start of polymerization is, for example, preferably 0.001% by mass or more and 2% by mass or less, more preferably 0.005% by mass or more and 1% by mass or less, and even more preferably 0.01% by mass or more and 0.5% by mass or less, relative to the total mass of the reaction liquid.
Within the above range, the polymerization reaction can proceed stably, and therefore the complexation with the polyanion present in the reaction system proceeds stably, making it possible to easily obtain a conductive complex with good conductivity.

The content of the polyanion in the reaction solution immediately before the start of polymerization is preferably set based on the content ratio relative to the monomer.

The weight average molecular weight Mw of the polyanion contained in the reaction solution is preferably 200,000 or more and 1,000,000 or less. In other words, it is preferable that the weight average molecular weight of the polyanion does not change in the reaction solution.
As a method for synthesizing a polyanion with a specific weight-average molecular weight Mw, for example, as shown in the examples described below, the weight-average molecular weight Mw can be adjusted by adjusting the amount of oxidizing agent added to polymerize the monomers that constitute the polyanion. Specifically, increasing the concentration of the oxidizing agent can reduce the weight-average molecular weight of the polyanion formed by polymerization of the monomers. This method can produce, for example, polystyrene sulfonic acid with a weight-average molecular weight Mw of 100,000 to 1,200,000.

The above method produces a conductive polymer dispersion containing a conductive complex including a π-conjugated conductive polymer and a polyanion, and water, in which the mass ratio of the π-conjugated conductive polymer to the polyanion is (1:2) to (1:5), and the weight-average molecular weight Mw of the polyanion is 200,000 or more and 1,000,000 or less.

Next, the conductive polymer dispersion of the first embodiment can be easily obtained by dispersing the conductive polymer dispersion using a disperser.

An example of a disperser used in this embodiment is one that extracts a portion of the dispersed sample from a holding tank (first container) that stores the dispersed sample, sends it into the disperser body, disperses it, and then collects it in another tank (collection tank; second container).

In the method for producing a conductive polymer dispersion according to this embodiment, controlling the temperature of the conductive polymer dispersion during dispersion treatment makes it easier to obtain a conductive polymer dispersion with the desired viscosity and particle size.

From the perspective of obtaining a conductive polymer dispersion having the viscosity and particle size described in the first embodiment, the liquid temperature (inlet temperature) of the conductive polymer dispersion to be subjected to dispersion treatment, the liquid temperature of the conductive polymer dispersion during dispersion, and the liquid temperature (outlet temperature) of the conductive polymer dispersion discharged from the main body of the disperser (the center where the dispersed sample is stirred) are preferably adjusted to 14°C or higher and 25°C or lower, and more preferably adjusted to 15°C or higher and 20°C or lower. In this case, the temperature of the dispersed sample stored in the collection kiln after dispersion treatment (inside-kiln solution temperature) is also preferably adjusted to 14°C or higher and 25°C or lower, and more preferably adjusted to 15°C or higher and 20°C or lower.

When dispersing the conductive polymer dispersion using a disperser at the above temperature settings, there are no particular restrictions on the time for the dispersion process. The dispersion process can be repeated while monitoring the viscosity and particle size of the dispersed conductive polymer dispersion until the desired viscosity and particle size are achieved.

Since the temperature of the conductive polymer dispersion can be easily controlled during, before, and after dispersion as described above, it is preferable to carry out the dispersion treatment in this embodiment as follows: That is, it is preferable to hold the conductive polymer dispersion before the dispersion treatment in a first container adjusted to a temperature of 14° C. or higher and 25° C. or lower, gradually introduce the conductive polymer dispersion from the first container into a disperser main body to carry out the dispersion treatment, and then sequentially discharge the dispersed conductive polymer dispersion from the disperser main body into a second container adjusted to a temperature of 14° C. or higher and 25° C. or lower and collect it.
The conductive polymer dispersion held in the first container is fed little by little into the disperser body to be dispersed, and the conductive polymer dispersion after dispersion treatment is recovered little by little from the disperser body into the second container, thereby making it possible to more reliably control the liquid temperature and the degree of dispersion during the dispersion treatment. Note that if one dispersion treatment (one pass) is insufficient, the dispersion treatment may be carried out again in the same manner.

By the above method, the conductive polymer dispersion liquid of the first embodiment can be obtained.
Since the dispersion liquid after the dispersion treatment is the conductive polymer dispersion liquid of the first embodiment, the dispersion medium of the conductive polymer dispersion liquid to be subjected to the dispersion treatment is preferably water or an aqueous dispersion medium, as described above, and more preferably water.

The content of the conductive complex relative to the total mass of the conductive polymer dispersion subjected to dispersion treatment is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 2% by mass or less.

It is preferable to remove the catalyst and oxidizing agent added to the reaction liquid from the conductive polymer dispersion to be subjected to the dispersion treatment before the dispersion treatment.
Examples of removal methods include a method of bringing the conductive polymer dispersion into contact with an ion exchange resin to adsorb the catalyst and oxidant onto the ion exchange resin, and a method of ultrafiltrating the conductive polymer dispersion to replace the dispersion medium and remove the catalyst and oxidant. Of these, the method using an ion exchange resin is preferred because it is simple. The ion exchange resin is preferably a combination of a cation exchange resin and an anion exchange resin.

<Conductive film and manufacturing method thereof>
A third aspect of the present invention is a method for producing a conductive film, comprising a step of applying the conductive polymer dispersion of the first aspect or the coating material of the second aspect to at least one surface of a film substrate to form a coating film.

A fourth aspect of the present invention is a conductive film having a conductive layer formed on at least one surface of a film substrate, the conductive layer being composed of the conductive polymer dispersion of the first aspect or a cured layer of the coating material of the second aspect. The conductive film of this aspect can be produced by the production method of the third aspect.

(Conductive film)
The conductive layer of the conductive film of this embodiment contains a conductive complex containing a π-conjugated conductive polymer and a polyanion.
When the conductive polymer dispersion applied to the film substrate contains a binder component, the conductive layer contains the binder component or a cured product of the binder component.
The average thickness of the conductive layer is preferably 10 nm or more and 20,000 nm or less, more preferably 20 nm or more and 10,000 nm or less, and even more preferably 30 nm or more and 5,000 nm or less. When the average thickness of the conductive layer is equal to or more than the lower limit, the conductive layer exhibits excellent conductivity, and when it is equal to or less than the upper limit, the conductive layer is difficult to peel off from the film substrate.
The average thickness of the conductive layer is determined by measuring the thickness at any 10 points and averaging the measured values.

Examples of the film substrate used in the production method of this embodiment include plastic films and paper.
Examples of film substrate resins that constitute plastic films include ethylene-methyl methacrylate copolymer resin, ethylene-vinyl acetate copolymer resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacrylate, polycarbonate, polyvinylidene fluoride, polyarylate, styrene-based elastomers, polyester-based elastomers, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyimide, cellulose triacetate, cellulose acetate propionate, etc. Among these film substrate resins, polyethylene terephthalate and cellulose triacetate are preferred because they are inexpensive and have excellent mechanical strength.
The resin for the film substrate may be amorphous or crystalline.
The film substrate may be unstretched or stretched.
Furthermore, the film substrate may be subjected to a surface treatment such as corona discharge treatment, plasma treatment, or flame treatment in order to further improve the adhesion of the conductive layer formed from the conductive polymer dispersion.

The average thickness of the film substrate is preferably 10 μm or more and 500 μm or less, and more preferably 20 μm or more and 200 μm or less. When the average thickness of the film substrate is equal to or more than the lower limit, the film is less likely to break, and when the average thickness is equal to or less than the upper limit, the film can have sufficient flexibility.
The thickness of the film substrate is determined by measuring the thickness at any 10 points and averaging the measured values.

(Coating process)
Examples of the method for applying the conductive polymer dispersion in the application step include application methods using a coater such as a gravure coater, a roll coater, a curtain flow coater, a spin coater, a bar coater, a reverse coater, a kiss coater, a fountain coater, a rod coater, an air doctor coater, a knife coater, a blade coater, a cast coater, or a screen coater; spraying methods using a sprayer such as an air spray, an airless spray, or a rotor dampening; and immersion methods such as dipping.
Among the above, a bar coater is often used because it allows for easy application.
The amount of the conductive polymer dispersion to be applied to the film substrate is not particularly limited, but is preferably in the range of 0.1 g/m ² or more and 10.0 g/m ² or less in terms of solid content.

(drying process)
Examples of methods for drying the coating film include heat drying and vacuum drying. Heat drying can be performed using conventional methods such as hot air heating and infrared heating. When heat drying is used, the heating temperature is appropriately set depending on the dispersion medium used, and can be set, for example, from 50°C to 150°C. Here, the heating temperature is the set temperature of the drying device.
When the conductive polymer dispersion contains an active energy ray-curable binder component, the method may further include an active energy ray irradiation step of irradiating the dried conductive polymer coating film with active energy rays after the drying step. The active energy ray irradiation step increases the rate at which the conductive layer is formed, thereby improving the productivity of the conductive film.
When the active energy ray irradiation step is included, examples of the active energy ray to be used include ultraviolet rays, electron beams, visible light, etc. Examples of light sources that can be used for ultraviolet rays include ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, xenon arc lamps, and metal halide lamps.
The illuminance of ultraviolet irradiation is preferably 100 mW/ ^cm2 or more. If the illuminance is less than 100 mW/ ^cm2 , the active energy ray-curable binder component may not be sufficiently cured. Furthermore, the integrated light dose is preferably 50 mJ/ ^cm2 or more. If the integrated light dose is less than 50 mJ/ ^cm2 , sufficient crosslinking may not occur. Note that the illuminance and integrated light dose in this specification are values measured using a Topcon UVR-T1 (industrial UV checker, receiver: UD-T36, measurement wavelength range: 300 nm to 390 nm, peak sensitivity wavelength: approximately 355 nm).

(Production Example 1) Production of polystyrene sulfonic acid 206 g of sodium styrene sulfonate was dissolved in 1,000 ml of ion-exchanged water, and while stirring at 80°C, 1.14 g of an oxidizing agent solution of ammonium persulfate previously dissolved in 10 ml of water was added dropwise over 20 minutes, and the solution was stirred for 12 hours.
To the resulting sodium polystyrene sulfonate solution, 1000 ml of sulfuric acid diluted to 10% by mass was added, and about 1000 ml of the solvent from the resulting polystyrene sulfonic acid solution was removed by ultrafiltration. Next, 2000 ml of ion-exchanged water was added to the remaining solution, and about 2000 ml of the solvent was removed by ultrafiltration, and the polystyrene sulfonic acid was washed with water. This water-washing procedure was repeated three times.
Water in the resulting solution was removed under reduced pressure to obtain colorless solid polystyrene sulfonic acid.
The weight-average molecular weight Mw of the polystyrene sulfonate (PSS) obtained above was measured by gel permeation chromatography (GPC) using pullulan of known weight-average molecular weight as the standard substance, and the weight-average molecular weight was found to be 200,000.
The weight-average molecular weight was measured using a Shimadzu Corporation high-performance liquid chromatograph Prominence, 0.1% _NaNO3 aqueous solution as the solvent, a Shodex OHpack SB-806M HQ column, and a RID-20A detector, with the solvent temperature set to 40°C, the flow rate set to 0.6 ml/min, 100 μl of sample injected, and the PSS concentration in the sample set to 0.1 mass% using the analysis software LabSolutions (Shimadzu Corporation).
Next, 10 g of the obtained polystyrene sulfonic acid was dissolved in 90 g of ion-exchanged water to obtain a 10% by mass aqueous solution of polystyrene sulfonic acid.

(Production Example 2) Production of polystyrene sulfonic acid A 10% by mass aqueous solution of polystyrene sulfonic acid having a weight average molecular weight of 500,000 was obtained in the same manner as in Production Example 1, except that the amount of ammonium persulfate was changed from 1.14 g to 0.86 g.

(Production Example 3) Production of polystyrene sulfonic acid A 10% by mass aqueous solution of polystyrene sulfonic acid having a weight average molecular weight of 1,000,000 was obtained in the same manner as in Production Example 1, except that the amount of ammonium persulfate was changed from 1.14 g to 0.57 g.

(Production Example 4) Production of polystyrene sulfonic acid A 10% by mass aqueous solution of polystyrene sulfonic acid having a weight average molecular weight of 100,000 was obtained in the same manner as in Production Example 1, except that the amount of ammonium persulfate was changed from 1.14 g to 1.71 g.

(Production Example 5) Production of polystyrene sulfonic acid A 10% by mass aqueous solution of polystyrene sulfonic acid having a weight average molecular weight of 1,200,000 was obtained in the same manner as in Production Example 1, except that 1.14 g of ammonium persulfate in Production Example 1 was changed to 0.29 g.

Example 1
0.5 g of 3,4-ethylenedioxythiophene, 1.5 g of the aqueous solution of polystyrene sulfonic acid having a weight average molecular weight of 200,000 as prepared in Production Example 1, and 89.5 g of ion-exchanged water were mixed together.
The resulting mixed solution was kept at 20°C and, while being stirred, an oxidant solution prepared by dissolving 0.03 g of ferric sulfate in 4.97 g of ion-exchanged water and a catalyst solution prepared by dissolving 1.1 g of ammonium persulfate in 8.9 g of ion-exchanged water were slowly added, and the resulting reaction solution was stirred for 24 hours to allow the reaction to occur.
The above reaction yielded a conductive polymer dispersion containing a conductive complex (PEDOT-PSS) containing the π-conjugated conductive polymer poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid, and water as a dispersion medium. The PEDOT:PSS (mass ratio) in the conductive complex obtained here was 1:3.

To this conductive polymer dispersion, 13.2 g of Duolite C255LFH (a cation exchange resin manufactured by Sumika Chemtex Co., Ltd.) and 13.2 g of Duolite A368S (anion exchange resin manufactured by Sumika Chemtex Co., Ltd.) were added, and the ion exchange resin was removed by filtration, yielding a conductive polymer dispersion from which the oxidant and catalyst had been removed. The conductive complex concentration in the resulting conductive polymer dispersion was approximately 1.7% by mass.

The obtained conductive polymer dispersion was dispersed at a rotation speed of 10,000 rpm using a pipeline homogenizer (manufactured by Primix Corporation). During this process, the temperature inside the holding tank (dispersion sample temperature) storing the conductive polymer dispersion before supplying it to the disperser was set to 14°C, and the cooling water temperature of the pipeline homogenizer (disperser main body) was set to 10°C, resulting in a conductive polymer dispersion with an outlet temperature of 14°C. During this dispersion, the conductive polymer dispersion introduced into the holding tank (first container) was gradually supplied to the pipeline homogenizer (disperser main body) and dispersed, and then sequentially discharged from the pipeline homogenizer at the outlet temperature and collected in a collection kiln (second container). During this dispersion process, the cooling water temperatures of the holding tank and collection kiln were set to 14°C, and the entire amount of the conductive polymer dispersion was dispersed while maintaining the temperature at 14°C.
The solid content (non-volatile components) of the conductive polymer dispersion obtained through one-pass dispersion treatment was measured, and ion-exchanged water was added to adjust the solid content to 1.3 mass %, and the viscosity and particle size of the obtained conductive polymer dispersion were measured by the methods described below. The results are shown in Table 1A.

Next, 6.5 g of ion-exchanged water, 7.5 g of methanol, and 15 g of isopropanol were added to 1 g of the conductive polymer dispersion whose viscosity and particle size had been measured, to obtain a coating material.
The above coating material was applied to a PET film (Lumirror T60 manufactured by Toray Industries, Inc.) using a #4 bar coater and dried at 100°C for 1 minute to obtain a conductive film. The surface resistance of the conductive film immediately after production was measured using the method described below. The results are shown in Table 1A.
The coating material was then left at 25°C for 24 hours, and then applied to a PET film using a #4 bar coater. The film was then dried at 100°C for 1 minute to obtain a conductive film. The surface resistance of the conductive film immediately after production was measured using the method described below. The results are shown in Table 1A.

[Viscosity measurement method]
As described above, a conductive polymer dispersion liquid having a concentration of 1.3% by mass and containing water as a dispersion medium was used as a sample, and the viscosity was measured at 25°C using a tuning fork vibration viscometer (model number: SV-10, manufactured by A&D Co.) in accordance with JIS Z8803:2011 (Viscosity measurement method using a vibration viscometer). 1 Pa s (pascal second) was converted to 1000 cP (centipoise).

[Method for measuring particle size]
As described above, a conductive polymer dispersion with a concentration of 1.3% by mass and containing water as a dispersion medium was diluted 10 times with distilled water, and the resulting sample (i.e., a concentration of 0.13% by mass) was used to measure the cumulant average particle size at 25°C by dynamic light scattering (ZETA Potential/Particle Size/Molecular Weight Measurement System ELSZ-2000ZS, manufactured by Otsuka Electronics Co., Ltd.).

[Measurement of surface resistance value]
For the conductive films produced in each example, the surface resistance value of the conductive layer was measured using a resistivity meter (Hiresta manufactured by Nitto Seiko Analytech Co., Ltd.) under the condition of an applied voltage of 10 V. In the table, "1.0E+09" means "1.0 × 10 ⁹ ," and the same applies to other values.

Example 2
Conductive films were prepared in two batches in the same manner as in Example 1, except that 10 g of the polystyrene sulfonic acid aqueous solution of Production Example 1 and 94.5 g of ion-exchanged water were used, changing the mass ratio of PEDOT:PSS to 1:2, and the surface resistance values of the films were measured. The results are shown in Table 1A.

Example 3
Conductive films were prepared in two batches in the same manner as in Example 1, except that 25 g of the polystyrene sulfonic acid aqueous solution of Production Example 1 and 79.5 g of ion-exchanged water were used, changing the mass ratio of PEDOT:PSS to 1:5. The surface resistance values of the films were measured. The results are shown in Table 1A.

(Comparative Example 1)
An attempt was made to prepare a conductive polymer dispersion in the same manner as in Example 1, except that in Example 1, 5 g of the polystyrene sulfonic acid aqueous solution of Production Example 1 and 99.5 g of ion-exchanged water were used, changing the mass ratio of PEDOT:PSS to 1:1. However, the PEDOT-PSS could not be sufficiently dispersed, and a coating material could not be prepared, so the attempt was discontinued.

(Comparative Example 2)
Conductive films were prepared in two batches in the same manner as in Example 1, except that the mass ratio of PEDOT:PSS was changed to 1:7.5 by using 37.5 g of the polystyrene sulfonic acid aqueous solution of Production Example 1 and 67 g of ion-exchanged water, and the surface resistance values of the films were measured. The results are shown in Table 1A.

<Summary of results (1)>
In the conductive polymer dispersions of Examples 1 to 3 according to the present invention, the PEDOT:PSS mass ratio was 1:2 to 1:5, the weight-average molecular weight Mw of the PSS in the PEDOT-PSS ranged from 200,000 to 1,000,000, and the dispersions were prepared using a disperser at a predetermined temperature. Therefore, the viscosity measured under predetermined conditions was 35 cP to 45 cP, and the particle size was less than 500 nm. As a result, the dispersion stability of the conductive polymer dispersions was excellent, and the increase in surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was reduced to less than four times the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation. In contrast, in Comparative Examples 7 to 9 described below, R1/R0 increased by more than 12 times.
In Comparative Example 1, the mass ratio of PEDOT:PSS was too low, so that PEDOT-PSS could not be dispersed sufficiently, and a conductive layer could not be formed.
In Comparative Example 2, the mass ratio of PEDOT:PSS was too high, resulting in a film with such high resistance that the conductivity of the conductive layer was unmeasurable.

(Examples 4 to 6, Comparative Examples 3 and 4)
Tests were conducted in the same manner as in Examples 1 to 3 and Comparative Examples 1 and 2, except that the cooling water temperature of the pipeline homogenizer was set to 15° C., a conductive polymer dispersion liquid was obtained with an outlet temperature of 20° C., and the temperatures of the solutions in the holding tank and the collecting kiln were set to 20° C. The results are shown in Table 1A.

<Summary of results (2)>
In the conductive polymer dispersions of Examples 4 to 6 according to the present invention, the PEDOT:PSS mass ratio was 1:2 to 1:5, the weight-average molecular weight Mw of the PSS in the PEDOT-PSS ranged from 200,000 to 1,000,000, and the dispersions were prepared using a disperser at a predetermined temperature. Therefore, the viscosity measured under predetermined conditions was 35 cP to 45 cP, and the particle size was less than 500 nm. Therefore, the dispersion stability of the conductive polymer dispersions was excellent. The increase in the surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was reduced to less than three times the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation. In contrast, in Comparative Examples 7 to 9 described below, the R1/R0 increased by more than 12 times.
In Comparative Example 3, the mass ratio of PEDOT:PSS was too low, so that PEDOT-PSS could not be dispersed sufficiently, and a conductive layer could not be formed.
In Comparative Example 4, the mass ratio of PEDOT:PSS was too high, resulting in a film with such high resistance that the conductivity of the conductive layer was unmeasurable.

(Examples 7 to 9, Comparative Examples 5 and 6)
Tests were conducted in the same manner as in Examples 1 to 3 and Comparative Examples 1 and 2, except that the cooling water temperature of the pipeline homogenizer was set to 20° C., a conductive polymer dispersion liquid with an outlet temperature of 25° C. was obtained, and the temperatures of the solutions in the holding tank and the collecting kiln were set to 25° C. The results are shown in Table 1A.

<Summary of results (3)>
In the conductive polymer dispersions of Examples 7 to 9 according to the present invention, the PEDOT:PSS mass ratio was 1:2 to 1:5, the weight-average molecular weight Mw of the PSS in the PEDOT-PSS ranged from 200,000 to 1,000,000, and the dispersions were prepared using a disperser at a predetermined temperature. Therefore, the viscosity measured under predetermined conditions was 35 cP to 45 cP, and the particle size was less than 500 nm. Therefore, the dispersion stability of the conductive polymer dispersions was excellent. The increase in the surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was reduced to less than two times the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation. In contrast, in Comparative Examples 7 to 9 described below, the R1/R0 increased by more than 12 times.
In Comparative Example 5, the mass ratio of PEDOT:PSS was too low, so that PEDOT-PSS could not be dispersed sufficiently, and a conductive layer could not be formed.
In Comparative Example 6, the mass ratio of PEDOT:PSS was too high, resulting in a film with such high resistance that the conductivity of the conductive layer was unmeasurable.

(Comparative Examples 7 to 11)
Tests were conducted in the same manner as in Examples 1 to 3 and Comparative Examples 1 and 2, except that the cooling water temperature of the pipeline homogenizer was set to 5° C., a conductive polymer dispersion was obtained with an outlet temperature of 10° C., and the temperatures of the solutions in the holding tank and the collecting kiln were set to 10° C. The results are shown in Table 1A.

<Summary of results (4)>
In Comparative Examples 7 to 9, the viscosity measured under specified conditions was less than 35 cP, which resulted in poor dispersion stability of the conductive polymer dispersion, and the increase in surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was greater than the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation, being 12 times or more higher.
In Comparative Example 10, the mass ratio of PEDOT:PSS was too low, so that PEDOT-PSS could not be dispersed sufficiently, and a conductive layer could not be formed.
In Comparative Example 11, the mass ratio of PEDOT:PSS was too high, resulting in a film with such high resistance that the conductivity of the conductive layer was unmeasurable.

(Comparative Examples 12 to 16)
Tests were conducted in the same manner as in Examples 1 to 3 and Comparative Examples 1 and 2, except that the cooling water temperature of the pipeline homogenizer was set to 25° C., a conductive polymer dispersion liquid was obtained with an outlet temperature of 30° C., and the temperatures of the solutions in the holding tank and the collecting kiln were set to 30° C. The results are shown in Table 1B.

<Summary of results (5)>
In Comparative Examples 12 to 14, the viscosity measured under the specified conditions exceeded 45 cP and the particle size was 500 nm or larger. As a result, the dispersion stability of the conductive polymer dispersion was poor. Although it was possible to form a conductive layer by applying the paint immediately after preparation, the PEDOT-PSS had gelled in the paint left for 24 hours after preparation, and the dispersion state had deteriorated, so the experiment was discontinued.
In Comparative Example 15, the mass ratio of PEDOT:PSS was too low, so that PEDOT-PSS could not be dispersed sufficiently, and a conductive layer could not be formed.
In Comparative Example 16, the mass ratio of PEDOT:PSS was too high, resulting in a film with such high resistance that the conductivity of the conductive layer was unmeasurable.

Example 10
Conductive films were produced in two batches in the same manner as in Example 1, except that 15 g of the aqueous solution of polystyrene sulfonic acid having a weight-average molecular weight of 500,000 in Production Example 2 was used, and the surface resistance values of the films were measured. The results are shown in Table 1B.

Example 11
The test was carried out in the same manner as in Example 10, except that the cooling water temperature of the pipeline homogenizer was set to 15° C., a conductive polymer dispersion liquid was obtained with an outlet temperature of 20° C., and the temperatures of the solutions in the holding tank and the collecting furnace were set to 20° C. The results are shown in Table 1B.

Example 12
The test was carried out in the same manner as in Example 10, except that the cooling water temperature of the pipeline homogenizer was set to 20° C., a conductive polymer dispersion liquid with an outlet temperature of 25° C. was obtained, and the temperatures of the solutions in the holding tank and the collecting furnace were set to 25° C. The results are shown in Table 1B.

(Comparative Example 17)
The test was carried out in the same manner as in Example 10, except that the cooling water temperature of the pipeline homogenizer was set to 5° C., a conductive polymer dispersion was obtained with an outlet temperature of 10° C., and the temperatures of the solutions in the holding tank and the collecting furnace were set to 10° C. The results are shown in Table 1B.

(Comparative Example 18)
The test was carried out in the same manner as in Example 10, except that the cooling water temperature of the pipeline homogenizer was set to 25° C., a conductive polymer dispersion liquid was obtained with an outlet temperature of 30° C., and the temperatures of the solutions in the holding tank and the collecting furnace were set to 30° C. The results are shown in Table 1B.

<Summary of results (6)>
In the conductive polymer dispersions of Examples 10 to 12 according to the present invention, the PEDOT:PSS mass ratio was 1:2 to 1:5, the weight-average molecular weight Mw of the PSS in the PEDOT-PSS was in the range of 200,000 to 1,000,000, and the dispersions were prepared using a disperser at a predetermined temperature, resulting in a viscosity of 35 cP to 45 cP when measured under predetermined conditions and a particle size of less than 500 nm. This resulted in excellent dispersion stability for the conductive polymer dispersions, and the increase in surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was reduced to less than three times the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation.
In Comparative Example 17, the viscosity measured under specified conditions was less than 35 cP, which resulted in poor dispersion stability of the conductive polymer dispersion, and the increase in surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was 10 times higher than the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation.
In Comparative Example 18, the viscosity measured under specified conditions exceeded 45 cP and the particle size was 500 nm or larger. As a result, the dispersion stability of the conductive polymer dispersion was poor, and although it was possible to form a conductive layer by applying the paint immediately after preparation, the PEDOT-PSS had gelled in the paint left for 24 hours after preparation, and the dispersion state had deteriorated, so the experiment was discontinued.

(Examples 13 to 15, Comparative Examples 19 to 20)
Conductive films were produced in two batches and their surface resistance values were measured in the same manner as in Examples 10 to 12 and Comparative Examples 17 and 18, except that the aqueous solution of polystyrene sulfonic acid having a weight-average molecular weight of 1,000,000 used in Production Example 3 was used. The results are shown in Table 1B.

<Summary of results (7)>
In the conductive polymer dispersions of Examples 13 to 15 according to the present invention, the PEDOT:PSS mass ratio was 1:2 to 1:5, the weight-average molecular weight Mw of the PSS in the PEDOT-PSS was in the range of 200,000 to 1,000,000, and the dispersions were prepared using a disperser at a predetermined temperature, resulting in a viscosity of 35 cP to 45 cP when measured under predetermined conditions and a particle size of less than 500 nm. As a result, the dispersion stability of the conductive polymer dispersions was excellent, and the increase in the surface resistance R1 of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation (R1/R0) was reduced to less than 1-fold, compared to the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation.
In Comparative Example 19, the viscosity measured under specified conditions was less than 35 cP, which resulted in poor dispersion stability of the conductive polymer dispersion, and the increase in surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was 10 times higher than the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation.
In Comparative Example 20, the viscosity measured under specified conditions exceeded 45 cP and the particle size was 500 nm or larger. As a result, the dispersion stability of the conductive polymer dispersion was poor, and although it was possible to form a conductive layer by applying the paint immediately after preparation, the PEDOT-PSS had gelled in the paint left for 24 hours after preparation, and the dispersion state had deteriorated, so the experiment was discontinued.

(Comparative Examples 21 to 23)
Conductive films were produced in two batches in the same manner as in Examples 10 to 12, except that the aqueous solution of polystyrene sulfonic acid having a weight-average molecular weight of 100,000 in Production Example 4 was used, and the surface resistance values of the films were measured. The results are shown in Table 1B.

<Summary of results (8)>
In Comparative Examples 21 to 23, the viscosity measured under the specified conditions was less than 35 cP.
As a result, the dispersion stability of the conductive polymer dispersion was poor, and the increase in surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left to stand for 24 hours after preparation was 10 times or more higher than the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation.

(Comparative Examples 24 to 26)
Conductive films were produced in two batches in the same manner as in Examples 10 to 12, except that the aqueous solution of polystyrene sulfonic acid having a weight-average molecular weight of 1,200,000 in Production Example 5 was used, and the surface resistance values thereof were measured. The results are shown in Table 1B.

<Summary of Results (9)>
In Comparative Examples 24 to 26, the viscosity measured under the specified conditions exceeded 45 cP and the particle size was 500 nm or larger. As a result, the dispersion stability of the conductive polymer dispersion was poor, and although it was possible to form a conductive layer by applying the coating immediately after preparation, after leaving it for 24 hours after dispersion, the PEDOT-PSS had gelled and the dispersion state had deteriorated, so the experiment was discontinued.

Example 16
In the same manner as in Example 1, PEDOT-PSS was synthesized, and a conductive polymer dispersion containing water as a dispersion medium was prepared. The oxidizing agent and catalyst were removed using an ion exchange resin to obtain a conductive polymer dispersion.
The obtained conductive polymer dispersion was dispersed using a NanoVata (manufactured by Yoshida Kikai Kogyo Co., Ltd.). The NanoVata is a homogenizer that uses the shear force of turbulence generated in a fluid by passing the fluid through a nozzle (micropores) at high speed and pressure to disperse fine particles in the fluid. The dispersion pressure at the nozzle was set to 150 MPa. The temperature inside the holding tank storing the conductive polymer dispersion before supplying it to the nozzle (dispersion sample temperature) was set to 14°C, the temperature of the cooling water around the nozzle (homogenizer cooling water temperature) was set to 10°C, and the outlet temperature of the conductive polymer dispersion discharged from the nozzle and the temperature inside the kiln where it was collected (kiln solution temperature) were all set to 14°C, and a one-pass dispersion process was performed.
The solid content (non-volatile components) of the conductive polymer dispersion obtained through the dispersion treatment was measured, and ion-exchanged water was added to adjust the solid content to 1.3 mass %, and the viscosity and particle size of the obtained conductive polymer dispersion were measured by the above-mentioned methods. The results are shown in Table 2.
Furthermore, using the conductive polymer dispersion obtained through the dispersion treatment, paints were prepared in the same manner as in Example 1, and conductive films were produced in two batches, and their surface resistance values were measured. The results are shown in Table 2.

(Example 17)
A conductive polymer dispersion was obtained and a coating material was prepared in the same manner as in Example 16, except that the temperature inside the holding tank (dispersion sample temperature) was set to 20°C, the cooling water temperature around the nozzle of the Nanovater (homogenizer cooling water temperature) was set to 15°C, and the outlet temperature of the conductive polymer dispersion discharged from the nozzle and the temperature inside the kiln for collecting it (inside the kiln solution temperature) were both set to 20°C, and a single-pass dispersion treatment was performed. Conductive polymer dispersions were obtained and coating materials were prepared, and conductive films were produced in two batches and their surface resistance values were measured. The results are shown in Table 2.

(Example 18)
A conductive polymer dispersion was obtained and a coating material was prepared in the same manner as in Example 16, except that the temperature inside the holding tank (dispersion sample temperature) was set to 25°C, the cooling water temperature around the nozzle of the Nanovater (homogenizer cooling water temperature) was set to 20°C, and the outlet temperature of the conductive polymer dispersion discharged from the nozzle and the temperature inside the kiln for collecting it (inside the kiln solution temperature) were both set to 25°C, and a single-pass dispersion treatment was performed. Conductive films were then produced in two batches and their surface resistance values were measured. The results are shown in Table 2.

(Comparative Example 27)
A conductive polymer dispersion was obtained and a coating material was prepared in the same manner as in Example 16, except that the temperature inside the holding tank (dispersion sample temperature) was set to 10°C, the cooling water temperature around the nozzle of the Nanovater (homogenizer cooling water temperature) was set to 5°C, and the outlet temperature of the conductive polymer dispersion discharged from the nozzle and the temperature inside the kiln for collecting it (inside the kiln solution temperature) were set to 10°C, and a single-pass dispersion treatment was performed. Conductive polymer dispersions were obtained and coating materials were prepared, and conductive films were produced in two batches and their surface resistance values were measured. The results are shown in Table 2.

(Comparative Example 28)
A conductive polymer dispersion was obtained and a coating material was prepared in the same manner as in Example 16, except that the temperature inside the holding tank (dispersion sample temperature) was set to 30°C, the cooling water temperature around the nozzle of the Nanovater (homogenizer cooling water temperature) was set to 25°C, and the outlet temperature of the conductive polymer dispersion discharged from the nozzle and the temperature inside the kiln for collecting it (inside the kiln solution temperature) were both set to 30°C, and a single-pass dispersion treatment was performed. Conductive polymer dispersions were obtained and coating materials were prepared, and conductive films were produced in two batches and their surface resistance values were measured. The results are shown in Table 2.

<Summary of results (10)>
In the conductive polymer dispersions of Examples 16 to 18 according to the present invention, the PEDOT:PSS mass ratio was 1:2 to 1:5, the weight-average molecular weight Mw of the PSS in the PEDOT-PSS was in the range of 200,000 to 1,000,000, and the dispersions were prepared using a Nanovater at a predetermined temperature, resulting in a viscosity of 35 cP to 45 cP when measured under predetermined conditions and a particle size of less than 500 nm. This resulted in excellent dispersion stability for the conductive polymer dispersions, and the increase in the surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was reduced to less than four times the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation.
In Comparative Example 27, the viscosity measured under specified conditions was less than 35 cP, which resulted in poor dispersion stability of the conductive polymer dispersion, and the increase in surface resistance R1 (R1/R0) of the conductive layer formed by applying a coating material that had been left for 24 hours after preparation was 30 times higher than the surface resistance R0 of the conductive layer formed by applying a coating material immediately after preparation.
In Comparative Example 28, the viscosity measured under the specified conditions was over 45 cP, and the particle size was 500 nm or more. Therefore, the dispersion stability of the conductive polymer dispersion was poor, and although it was possible to form a conductive layer by applying the coating immediately after preparation, after leaving it for 24 hours after preparation, the PEDOT-PSS had gelled and the dispersion state had deteriorated, so the experiment was discontinued.

Claims (3)

A reaction solution containing a monomer that forms a π-conjugated conductive polymer, a polyanion, and water,
a method for producing a conductive polymer dispersion, the method comprising: polymerizing the monomer to obtain a conductive polymer dispersion containing a conductive complex containing the π-conjugated conductive polymer and the polyanion, and water; and then dispersing the conductive polymer dispersion, wherein, in the dispersion treatment, the conductive complex is dispersed so that the viscosity at 25°C is 35 cP or more and 45 cP or less when the concentration of the conductive complex is adjusted to 1.3 mass % relative to the total mass of the obtained conductive polymer dispersion,
the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrene sulfonic acid;
a mass ratio of the π-conjugated conductive polymer to the polyanion is (1:2) to (1:5), and the weight average molecular weight Mw of the polyanion is 200,000 or more and 1,000,000 or less;
the conductive polymer dispersion before the dispersion treatment is held in a first container adjusted to a temperature of 14°C or higher and 25°C or lower, and after the conductive polymer dispersion held in the first container has reached the same temperature as that of the first container, the conductive polymer dispersion is gradually introduced from the first container into a disperser body and passed through a nozzle of the disperser body, thereby generating a high-speed shear force in the conductive polymer dispersion, thereby carrying out the dispersion treatment;
cooling the periphery of the nozzle during the dispersion treatment with cooling water having a temperature lower than that of the conductive polymer dispersion held in the first container;
the conductive polymer dispersion liquid after the dispersion treatment is sequentially discharged from the disperser body into a second container adjusted to a temperature of 14°C or higher and 25°C or lower, and collected. The method for producing a conductive polymer dispersion according to claim 1, wherein the particle size at 25°C is less than 500 nm when the concentration of the conductive complex in the conductive polymer dispersion that has undergone the dispersion treatment is adjusted to 0.13 mass%. a step of producing the conductive polymer dispersion by the production method according to claim 1 or 2;
A method for producing a conductive film, comprising applying the conductive polymer dispersion or a coating material containing the conductive polymer dispersion and a water-soluble organic solvent to at least one surface of a film substrate.