Method for producing a conductive polymer dispersion, and method for producing a conductive film

Abstract

A conductive polymer dispersion containing methanol and isopropanol is provided. [Solution] A method for producing a conductive polymer dispersion, comprising the steps of: adding methanol to a conductive polymer-water dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in water to obtain a mixed solution; and then adding isopropanol to the mixed solution to obtain a conductive polymer dispersion in which the conductive composite is dispersed in a dispersion medium containing water, methanol, and isopropanol.

Description

Technical Field

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

Background Art

[0002] A π-conjugated conductive polymer having a main chain composed of a π-conjugated system forms a conductive composite by doping with a polyanion having an anion group, and exhibits dispersibility in water. A antistatic technique is known in which a paint containing such a conductive composite is applied to a resin film to form a conductive layer on its surface. For example, Patent Document 1 proposes a paint further mixed with polyvinyl alcohol, an acrylic compound, and a polymerization initiator thereof. According to this paint, an antistatic film that can be stretched, has high water resistance of the conductive layer, and is excellent in mechanical strength can be produced with high productivity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the wettability of a conductive polymer aqueous dispersion containing only water as a solvent (hereinafter sometimes referred to as "conductive polymer-aqueous dispersion") is not high, and it may be difficult to form a uniform coating film on the surface of the resin film. In Patent Document 1, since polyvinyl alcohol or propylene glycol is added, the wettability is relatively high, but since the viscosity of the paint is high, there may be limitations on the use and coating method of the paint.

[0005] The present invention provides a conductive polymer dispersion containing methanol and isopropanol.

Means for Solving the Problems

[0006] [1] A method for producing a conductive polymer dispersion, comprising the steps of: adding methanol to a conductive polymer-water dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in water to obtain a mixed solution; and then adding isopropanol to the mixed solution to obtain a conductive polymer dispersion in which the conductive composite is dispersed in a dispersion medium containing water, methanol, and isopropanol. [2] The method for producing a conductive polymer dispersion according to [1], wherein the isopropanol is added when the temperature of the mixture is 1°C or more lower than the temperature immediately after the methanol is added. [3] The method for producing a conductive polymer dispersion according to [1] or [2], wherein the alcohol content in the conductive polymer-aqueous dispersion is 10% by mass or less relative to the total mass of the conductive polymer-aqueous dispersion. [4] A method for producing a conductive polymer dispersion according to any one of [1] to [3], wherein the water content relative to the total mass of the dispersion medium is 10% by mass or more and 30% by mass or less. [5] A method for producing a conductive polymer dispersion according to any one of [1] to [4], wherein the methanol content relative to the total mass of the dispersion medium is 15% by mass or more and 50% by mass or less. [6] A method for producing a conductive polymer dispersion according to any one of [1] to [5], wherein the content of the isopropanol relative to the total mass of the dispersion medium is 30% by mass or more and 70% by mass or less. [7] A method for producing a conductive polymer dispersion according to any one of [1] to [6], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene). [8] A method for producing a conductive polymer dispersion according to any one of [1] to [7], wherein the polyanion is polystyrene sulfonic acid. [9] A method for producing a conductive polymer dispersion according to any one of [1] to [8], further comprising the step of adding a binder resin to the conductive polymer dispersion. A method for manufacturing a conductive film, comprising the steps of: obtaining the conductive polymer dispersion by the manufacturing method described in any one of [1] to [9]; coating the conductive polymer dispersion with the conductive polymer dispersion with at least one surface of a film substrate; and drying the coated conductive polymer dispersion. [Effects of the Invention]

[0007] According to the present invention, it is possible to produce a conductive polymer dispersion that has good wettability on the surface of a resin film and can form a conductive layer with excellent conductivity.

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

[0009] In this specification and the claims, the lower and upper limits of the numerical ranges indicated by "~" are to be included within those numerical ranges. [Modes for carrying out the invention]

[0010] ≪Method for producing conductive polymer dispersions≫ A first aspect of the present invention is a method for producing a conductive polymer dispersion, comprising the steps of: adding methanol to a conductive polymer-aqueous dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in water to obtain a mixed solution; and then adding isopropanol to the mixed solution to obtain a conductive polymer dispersion in which the conductive composite is dispersed in a dispersion medium containing water, methanol, and isopropanol.

[0011] First, as an example of a method for preparing a conductive polymer-aqueous dispersion to which methanol is to be added, a preparation method having the following polymerization step will be described. Note that, in addition to the preparation method described below, conductive polymer-aqueous dispersions prepared by known methods can be used in this embodiment, and commercially available products can also be used.

[0012] [Polymerization process] This process involves polymerizing monomers that form a π-conjugated conductive polymer in a reaction solution containing at least one of an oxidizing agent and a catalyst, a polyanion, and water, thereby obtaining a conductive polymer-water dispersion containing a conductive composite comprising the π-conjugated conductive polymer and the polyanion, and water.

[0013] (Polyanion) Polyanions are polymers that have two or more monomer units containing anionic groups within their molecule. The anionic groups of polyanions function as dopants for π-conjugated conductive polymers, thereby improving the conductivity of those polymers. The anionic group of the polyanion is preferably a sulfo group or a carboxyl group. Specific examples of polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic acid esters having sulfo groups, polymethacrylic acid esters having sulfo groups (for example, poly(4-sulfobutyl methacrylate, polysulfoethyl methacrylate, polymethacryloyloxybenzene sulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and other polymers having sulfo groups, as well as polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropanecarboxylic acid), polyisoprene carboxylic acid, and other polymers having carboxyl groups. Polyanions may be homopolymers formed by the polymerization of a single monomer, or copolymers formed by the polymerization of two or more monomers. Among these polyanions, polymers having sulfo groups are preferred because they can achieve higher conductivity, and polystyrene sulfonic acid is even more preferred. The weight-average molecular weight of the polyanion is preferably between 10,000 and 1,000,000, and more preferably between 100,000 and 500,000.

[0014] The amount of the polyanion blended with respect to the total mass of the reaction solution is preferably, for example, 0.1% by mass or more and 3.0% by mass or less, more preferably 0.5% by mass or more and 2.5% by mass or less, and even more preferably 1.0% by mass or more and 2.0% by mass or less. Within the above range, a conductive polymer-aqueous dispersion with good dispersibility of the conductive composite can be easily obtained. Furthermore, the mixing ratio of the polyanion and monomer added to the reaction solution is reflected in the content ratio of the π-conjugated conductive polymer and polyanion contained in the conductive composite.

[0015] (Monomers that form π-conjugated conductive polymers) The monomer incorporated into the reaction solution is preferably one that forms the following π-conjugated conductive polymer. Any organic polymer whose main chain is composed of a π-conjugated system can be used as the π-conjugated conductive polymer. Examples include polypyrrole-based conductive polymers, polythiophene-based conductive polymers, polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylene-vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene-vinylene-based conductive polymers, and copolymers thereof. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferred, and from the viewpoint of transparency, polythiophene-based conductive polymers are more preferred.

[0016] Examples of polythiophene-based conductive polymers include polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3-chlorothiophene), poly(3-iodothiophene), poly(3-cyanothiophene), poly(3-phenylthiophene), poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene), poly(3-hydroxytiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-decyloxythiophene), poly(3-dodecyloxythiophene), poly(3-octadecyloxythiophene), poly(3,4-dihydroxytiophene), poly(3,4-dimethoxythiophene), poly(3,4-diethoxythiophene), poly(3,4-dipropoxythiophene), poly(3,4-dibutoxythiophene), poly(3,4-dihexyloxythiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-didodecyloxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene), poly(3-methyl-4-methoxythiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3-methyl-4-carboxybutylthiophene). Examples of polypyrrole-based conductive polymers include polypyrrole, poly(N-methylpyrrole), poly(3-methylpyrrole), poly(3-ethylpyrrole), poly(3-n-propylpyrrole), poly(3-butylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly(3-carboxypyrrole), poly(3-methyl-4-carboxypyrrole), poly(3-methyl-4-carboxyethylpyrrole), poly(3-methyl-4-carboxybutylpyrrole), poly(3-hydroxypyrrole), poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-butoxypyrrole), poly(3-hexyloxypyrrole), and poly(3-methyl-4-hexyloxypyrrole). Examples of polyaniline-based conductive polymers include polyaniline, poly(2-methylaniline), poly(3-isobutylaniline), poly(2-anilinesulfonic acid), and poly(3-anilinesulfonic acid). Among these π-conjugated conductive polymers, poly(3,4-ethylenedioxythiophene) is particularly preferred because of its excellent conductivity, transparency, and heat resistance. The π-conjugated conductive polymer contained in the conductive composite may be one type or two or more types. That is, the type of monomer blended in the reaction solution may be one type or two or more types.

[0017] The blending amount of the monomer with respect to the total mass of the reaction solution is preferably, for example, 0.01% by mass or more and 2.0% by mass or less, more preferably 0.1% by mass or more and 1.0% by mass or less, and even more preferably 0.3% by mass or more and 0.8% by mass or less. When it is within the above range, a conductive polymer-water dispersion with good dispersibility of the conductive composite can be easily obtained. Also, the blending ratio of the monomer and the polyanion blended in the reaction solution is reflected in the content ratio of the π-conjugated conductive polymer and the polyanion contained in the conductive composite.

[0018] (Dispersion medium) The dispersion medium constituting the reaction solution is preferably an aqueous dispersion medium containing water, as it allows polyanions to dissolve easily, ensures the polymerization reaction, and the conductive composite formed by the polymerization reaction—a π-conjugated conductive polymer combined with polyanions—is hydrophilic. Furthermore, dispersion media other than water may be included, as long as they do not significantly impair the effects of the present invention.

[0019] The dispersion medium other than water is preferably a water-soluble organic solvent. Here, the water-soluble organic solvent is an organic solvent whose solubility in 100g of water at 20°C is 1g or more, and examples include alcohol-based solvents, ketone-based solvents, and ester-based solvents. The dispersion medium may consist of one or more water-soluble organic solvents.

[0020] The water content relative to the total mass of the aqueous dispersion medium is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass. Within the above range, the dispersion stability of the conductive composite in the conductive polymer-aqueous dispersion is good.

[0021] (Oxidizing agent, catalyst) From the viewpoint of promoting the oxidative polymerization reaction of the monomer, it is preferable to include an oxidizing agent in the reaction solution. The oxidizing agent is preferably a salt because it has high solubility in aqueous dispersion media. Examples of such oxidizing agents include those containing sodium ions, ammonium ions, potassium ions, and the like.

[0022] The oxidizing agent is preferably a polymerization initiator. The polymerization initiator is preferably a radical polymerization initiator, and more preferably a persulfate, because it exhibits excellent polymerizability. Examples of persulfates include ammonium persulfate, sodium persulfate, and potassium persulfate.

[0023] The amount of the oxidizing agent relative to the total mass of the reaction solution is preferably, for example, 0.1% by mass or more and 1.5% by mass or less, more preferably 0.2% by mass or more and 1.0% by mass or less, and even more preferably 0.3% by mass or more and 0.7% by mass or less.

[0024] The reaction solution preferably contains a catalyst such as a transition metal compound, such as ferric chloride, ferric sulfate, ferric nitrate, or cupric chloride, along with the oxidizing agent. The amount of catalyst is adjusted appropriately in accordance with the amount of oxidizing agent.

[0025] The reaction temperature in the reaction solution can be, for example, 20 to 30°C. At this reaction temperature, the polymerization reaction is usually completed in about 4 to 12 hours. The completion of the polymerization reaction can be determined by measuring the amount of unreacted monomers in the reaction solution using known methods such as chromatography.

[0026] (Conductive composite) A conductive composite containing a π-conjugated conductive polymer and a polyanion is formed by the spontaneous doping of the π-conjugated conductive polymer, which is formed by the polymerization of the monomer in the reaction solution, with the polyanion. In water, the π-conjugated conductive polymer is positively charged and the polyanion is negatively charged, and it is thought that the two form the composite mainly through electrostatic interaction.

[0027] In the polyanions constituting the conductive composite, only some anionic groups are doped into the π-conjugated conductive polymer, while there are excess anionic groups that do not participate in doping. Since these excess anionic groups are hydrophilic, the conductive composite is water-dispersible. When the total number of anionic groups in a polyanion is considered to be 100 mol%, the excess anionic groups are preferably 30 mol% to 90 mol%, and more preferably 45 mol% to 75 mol%.

[0028] The polyanion content in the conductive composite is preferably in the range of 1 to 1000 parts by mass, more preferably 10 to 700 parts by mass, and even more preferably 100 to 500 parts by mass, per 100 parts by mass of the π-conjugated conductive polymer. If the polyanion content is above the lower limit, the doping effect on the π-conjugated conductive polymer tends to be stronger, resulting in higher conductivity. On the other hand, if the polyanion content is below the upper limit, the content ratio of the π-conjugated conductive polymer becomes sufficient, ensuring sufficient conductivity.

[0029] The upper limit of the content of the conductive composite relative to the total mass of the conductive polymer-aqueous dispersion obtained in the polymerization process is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, even more preferably 3.0% by mass or less, and most preferably 2.0% by mass or less. The lower limit is not particularly limited and can be set appropriately depending on the application of the conductive polymer-aqueous dispersion, for example, it may be 0.1% by mass or more. Keeping it below the above upper limit improves the dispersibility of the conductive composite in the conductive polymer-aqueous dispersion.

[0030] The conductive polymer-aqueous dispersion obtained in the polymerization process typically contains free ions derived from oxidizing agents, catalysts, or other materials. These impurities may be removed by contact with an ion exchange resin, ultrafiltration, or other methods.

[0031] The alcohol content in the conductive polymer-aqueous dispersion subjected to the next methanol addition step is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, and may be 0% by mass, based on the total mass of the conductive polymer-aqueous dispersion. Within the above range, a conductive polymer dispersion capable of forming a highly conductive layer can be easily obtained by taking advantage of the properties of methanol and isopropanol added in a later stage. The method for adjusting the composition of the dispersion medium constituting the conductive polymer-aqueous dispersion can be a conventional method, such as solvent substitution by ultrafiltration.

[0032] [Methanol addition step] The method of adding methanol to the conductive polymer-aqueous dispersion is not particularly limited; a predetermined amount may be added all at once, or small amounts may be added until the predetermined amount is reached. Generally, when water and methanol are mixed, heat is generated, and the temperature of the mixture rises. It is preferable to wait until the temperature of the mixture drops by 1°C or more, or for 1 minute or more, before adding isopropanol in the next step. That is, it is preferable to add isopropanol when the temperature of the mixture is 1°C or more lower than the temperature immediately after the methanol was added. The physicochemical state change of the conductive composite due to the addition of methanol can be stabilized during the above waiting period.

[0033] In this methanol addition step, it is preferable to add isopropanol when the temperature of the mixture has fallen to a predetermined temperature or more below the temperature immediately after methanol addition. Here, the predetermined temperature is preferably a higher value, for example, in the range of 1°C to 20°C (preferably in the range of 1°C to 10°C). When the elevated temperature returns to the original temperature (for example, 25°C), the conductivity of the conductive layer formed later can be improved.

[0034] The amount of methanol added per 100 parts by mass of conductive polymer-aqueous dispersion is preferably, for example, 100 parts by mass or more and 1000 parts by mass or less, more preferably 150 parts by mass or more and 700 parts by mass or less, and even more preferably 200 parts by mass or more and 500 parts by mass or less. If the value is above the lower limit of the above range, the wettability of the conductive polymer dispersion with respect to the resin film can be further improved. If the value is below the upper limit of the above range, the dispersibility of the conductive composite in the conductive polymer dispersion can be further improved.

[0035] Water may be added before adding methanol to the conductive polymer-aqueous dispersion.

[0036] [Isopropanol addition process] The method for further adding isopropanol (also known as 2-propanol) to a mixture of a conductive polymer-aqueous dispersion and methanol is not particularly limited; a predetermined amount may be added all at once, or small amounts may be added until the predetermined amount is reached. By adding isopropanol after methanol, a conductive polymer dispersion capable of forming a conductive layer with superior conductivity can be obtained compared to adding them in the reverse order. Furthermore, the combination of methanol and isopropanol allows for an increase in the alcohol concentration in the conductive polymer dispersion while maintaining the dispersion state of the conductive composite.

[0037] The amount of isopropanol added to 100 parts by mass of the mixture is preferably, for example, 10 parts by mass or more and 1000 parts by mass or less, more preferably 40 parts by mass or more and 200 parts by mass or less, and even more preferably 70 parts by mass or more and 150 parts by mass or less. If the value is above the lower limit of the above range, the wettability of the conductive polymer dispersion with respect to the resin film can be further improved. If the value is below the upper limit of the above range, the dispersibility of the conductive composite in the conductive polymer dispersion can be further improved.

[0038] <Conductive polymer dispersion> (Water content) The conductive polymer dispersion obtained by the manufacturing method of the first embodiment comprises a conductive composite and a dispersion medium. The dispersion medium, excluding the conductive composite which is a solid component (non-volatile component), comprises water, methanol, and isopropanol. The water content relative to the total mass of the dispersion medium is preferably, for example, 5% by mass or more and 40% by mass or less, more preferably 7% by mass or more and 35% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less. If the value is above the lower limit of the above range, the dispersibility of the conductive composite in the conductive polymer dispersion can be further improved. If the value is below the upper limit of the above range, the wettability of the conductive polymer dispersion with respect to the resin film can be further improved.

[0039] (Methanol content) The methanol content relative to the total mass of the dispersion medium is preferably, for example, 15% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 45% by mass or less, and even more preferably 25% by mass or more and 40% by mass or less. Within the above range, the wettability of the conductive polymer dispersion with respect to the resin film can be further enhanced, and a conductive layer with superior conductivity can be formed.

[0040] (Isopropanol content) The content of isopropanol relative to the total mass of the dispersion medium is preferably, for example, 30% to 70% by mass, more preferably 35% to 65% by mass, and even more preferably 40% to 60% by mass. It may also be 45% to 55% by mass. Within the above range, the wettability of the conductive polymer dispersion with respect to the resin film can be further enhanced, and a conductive layer with superior conductivity can be formed.

[0041] (Content of conductive composite) In the manufacturing method of this embodiment, the content of the conductive composite (i.e., π-conjugated conductive polymer and polyanion) relative to the total mass of the conductive polymer dispersion obtained after the addition of isopropanol is preferably 0.01% by mass or more and 1.00% by mass or less, more preferably 0.05% by mass or more and 0.60% by mass or less, and even more preferably 0.10% by mass or more and 0.30% by mass or less. If the value is above the lower limit of the above range, the amount of conductive composite contained in the conductive layer formed from the conductive polymer dispersion coating can be sufficiently increased, making it easier to form a conductive layer with excellent conductivity. If the value is below the upper limit of the above range, the dispersibility of the conductive composite in the conductive polymer dispersion can be further improved.

[0042] (Addition of optional ingredients) Binder components and other additives may be added to the conductive polymer dispersion obtained above.

[0043] [Addition of binder components] The manufacturing method of this embodiment may further include a step of adding a binder component to a conductive polymer dispersion to which methanol and isopropanol have been added. By using a conductive polymer dispersion containing a binder component, it is possible to improve the strength of the formed conductive layer and impart tackiness and release properties. The binder component is a resin other than the π-conjugated conductive polymer or the polyanion, or a precursor thereof, and is a thermoplastic resin, or a curable monomer or oligomer that hardens when the conductive layer is formed. The thermoplastic resin becomes the binder resin as is, and the resin formed by the hardening of the curable monomer or oligomer becomes the binder resin. In this embodiment, one type of binder component may be added, or two or more types may be added.

[0044] Specific examples of binder resins derived from binder components include epoxy resins, acrylic resins (acrylic compounds), polyester resins, polyurethane resins, polyimide resins, polyether resins, melamine resins, and silicones.

[0045] The curable monomer or oligomer may be a thermosetting monomer or oligomer, or a photocurable monomer or oligomer. Here, an oligomer is a polymer with a mass-average molecular weight of less than 10,000. Examples of curable monomers include acrylic monomers (acrylic compounds), epoxy monomers, and organosiloxanes. Examples of curable oligomers include acrylic oligomers (acrylic compounds), epoxy oligomers, and silicone oligomers (curable silicones). When acrylic monomers or acrylic oligomers are used as the binder component, the material can be easily cured by heating or light irradiation.

[0046] If the material contains a curable monomer or oligomer, it is preferable to further include a curing catalyst. For example, if the material contains a thermosetting monomer or oligomer, it is preferable to include a thermal polymerization initiator that generates radicals upon heating, and if the material contains a photocurable monomer or oligomer, it is preferable to include a photopolymerization initiator that generates radicals upon light irradiation.

[0047] The content ratio of the binder component (excluding the silicone compound described later) in the conductive polymer dispersion of this embodiment is preferably, for example, 1 part by mass or more and 10,000 parts by mass or less, more preferably 10 parts by mass or more and 5,000 parts by mass or less, and even more preferably 100 parts by mass or more and 1,000 parts by mass or less, per 1 part by mass of the conductive composite. If the value is above the lower limit of the above range, the properties of the binder component contained in the conductive layer formed by the conductive polymer dispersion of this embodiment can be fully exhibited. If the value is below the upper limit of the above range, sufficient conductivity of the conductive layer formed by the conductive polymer dispersion of this embodiment can be ensured.

[0048] (Water-dispersible polyester resin) Examples of binder components in this embodiment include water-dispersible polyester resins in which the polyester resin is dispersed in water. The water-dispersible polyester resin may be emulsified by also containing an emulsifier. By including a water-dispersible polyester resin in the conductive polymer dispersion of this embodiment, the adhesion of the conductive layer to the substrate can be improved, and the film strength of the conductive layer can be increased.

[0049] The water-dispersible polyester resin is preferably dispersible in 100g of distilled water at 25°C in an amount of 1g or more, preferably 5g or more, and more preferably 10g or more, and it is even more preferable that it can be emulsified within these preferred ranges.

[0050] Water-dispersible polyester resins preferably have hydrophilic functional groups such as hydroxyl groups, carboxyl groups, and sulfo groups. The presence of hydrophilic functional groups improves dispersibility in water. The hydrophilic functional groups of the water-dispersible polyester resin may form salts with cations such as sodium ions and potassium ions.

[0051] The content of the water-dispersible polyester resin in the conductive polymer dispersion is preferably 100 parts by mass or more and 50,000 parts by mass or less, more preferably 100 parts by mass or more and 10,000 parts by mass or less, and even more preferably 200 parts by mass or more and 2,000 parts by mass or less, per 100 parts by mass of the conductive composite. If the value is above the lower limit mentioned above, the adhesion and film strength of the conductive layer to the substrate will be further improved, and if it is below the upper limit mentioned above, a decrease in conductivity due to a reduced content of the conductive composite can be prevented.

[0052] (Silicone emulsion) Examples of binder components in this embodiment include silicone emulsions in which a silicone compound is dispersed in an aqueous dispersion medium to form an emulsion. A surfactant (emulsifier) ​​may also be included to form the emulsion of the silicone compound. As silicone compounds, silicone compounds included in known mold release agents can be used. Here, silicone refers to polymers collectively called organopolysiloxanes, which have a main chain (silicone skeleton) in which organic groups (e.g., alkyl groups or phenyl groups) are bonded to siloxane bonds. As organopolysiloxanes, polydimethylsiloxane (PDMS) is preferred, and those having reactive or non-reactive functional groups in part of the polydimethylsiloxane are also preferred. Furthermore, acrylic resins and alkyd resins having organopolysiloxanes in their side chains can also be used as the aforementioned silicone compounds.

[0053] As for silicone compounds, curable silicones are preferred because they exhibit stable release properties and excellent film-forming properties. The curable silicone may be either an addition-curing silicone or a condensation-curing silicone. When the curable silicone reacts, it hardens by forming a three-dimensional cross-linked structure. Examples of addition-curing silicones include linear polymers having siloxane bonds, specifically polydimethylsiloxane having vinyl groups at both ends of the linear chain, and hydrogensilane. A platinum-based curing catalyst may be used to accelerate curing. Specific examples of addition-curing silicones include KM-3951, X-52-6068, X-52-151, and X-52-6069 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0054] In this embodiment, the content of the silicone emulsion solids (non-volatile components) relative to the total mass of the conductive polymer dispersion is, for example, 0.1% by mass or more and 4.0% by mass or less. If the value is above the lower limit of the above range, sufficient release properties can be imparted to the conductive layer. If the value is below the upper limit of the above range, the conductivity of the conductive layer can be sufficiently maintained, and the adhesion of the conductive layer to the substrate can be maintained.

[0055] (High conductivity agent) The conductive polymer dispersion of this embodiment may contain a high-conductivity agent. Here, the π-conjugated conductive polymer, polyanion, and binder component mentioned above are not classified as high-conductivity agents. By including a high-conductivity agent in the conductive polymer dispersion, the conductivity of the formed conductive layer can be improved.

[0056] The highly conductive agent is preferably at least one compound selected from the group consisting of sugars, compounds having two or more hydroxyl groups, compounds having two or more carboxyl groups, compounds having one or more hydroxyl groups and one or more carboxyl groups, compounds having an amide group, compounds having an imide group, nitrogen-containing aromatic compounds, lactam compounds, and compounds having a glycidyl group. Here, hydroxyl groups and carboxyl groups are distinguished. The conductive polymer dispersion of this embodiment may contain one or more types of high-conductivity agents.

[0057] Examples of compounds having two or more hydroxyl groups (polyhydric alcohols) include thiodiglycol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), bisphenols (such as bisphenol A), sugar alcohols (such as xylitol and sorbitol), gallic acid, and alkyl gallic acid esters.

[0058] Examples of compounds having two or more carboxyl groups (polycarboxylic acids) include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedionic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid; and sulfur-containing carboxylic acids such as thiodipropionic acid.

[0059] Compounds containing an amide group (amide compounds) are monomolecular compounds that have an amide bond represented as -CO-NH- (where CO is a double bond) in their molecule. Specifically, examples include acetamide, malonamide, succinamide, maleamide, fumaamide, benzamide, naphthamide, phthalamide, isophthalamide, terephthalamide, nicotinamide, isonicotinamide, 2-fluamide, formamide, N-methylformamide, propionamide, propioamide, butylamide, isobutylamide, palmitoamide, stearylamide, oleamide, oxamide, glutaramide, adipamide, cinnamamide, glycolamide, lactamide, glyceramide, tartaramide, citrullamide, glyoxylamide, pyruoamide, acetacetamide, dimethylacetamide, benzylamide, anthranilamide, and ethylenediamine tetraamide. Examples of acrylamides include laacetamide, diacetamide, triacetamide, dibenzamide, trybenzamide, rhodanine, urea, 1-acetyl-2-thiourea, biuret, butylurea, dibutylurea, 1,3-dimethylurea, 1,3-diethylurea and their derivatives, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, 2-hydroxyethylacrylamide, 2-hydroxyethylmethacrylamide, N-methylolacrylamide, and N-methylolmethacrylamide.

[0060] Examples of nitrogen-containing aromatic compounds (aromatic compounds in which at least one nitrogen atom forms a ring structure) include pyrrole, indole, imidazole, 2-methylimidazole, 2-propylimidazole, N-methylimidazole, N-propylimidazole, N-butylimidazole, 1-(2-hydroxyethyl)imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole. Examples of derivatives include dazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, 2-aminobenzimidazole, 2-amino-1-methylbenzimidazole, 2-hydroxybenzimidazole, 2-(2-pyridyl)benzimidazole, pyridine, pyrimidine, pyrazine, and their alkyl-substituted derivatives (e.g., derivatives with C1-C4 alkyl groups such as methyl, ethyl, propyl, and butyl), halogen-substituted derivatives (e.g., derivatives with halogen groups such as fluoro, chloro, and brom), and nitrile-substituted derivatives.

[0061] The content of the high-conductivity agent relative to the total mass of the conductive polymer dispersion in this embodiment can be, for example, 0.001% by mass or more and 10% by mass or less. Within the above preferred range, the effect of improving conductivity by adding a high-conductivity agent can be obtained even more effectively.

[0062] (Other additives) The conductive polymer dispersion of this embodiment may contain other known additives. The additives are not particularly limited as long as the effects of the present invention are obtained, and for example, surfactants, inorganic conductive agents, defoaming agents, coupling agents, antioxidants, ultraviolet absorbers, etc. can be used. Examples of surfactants include nonionic, anionic, and cationic surfactants, but nonionic surfactants are preferred in terms of storage stability. Polymer-based surfactants such as polyvinylpyrrolidone may also be added. Examples of inorganic conductive agents include metal ions and conductive carbon. Metal ions can be generated by dissolving metal salts in water. Examples of defoaming agents include silicone resins, polydimethylsiloxanes, and silicone oils. Examples of coupling agents include silane coupling agents having a vinyl group or an amino group. Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and sugars. Examples of UV absorbers include benzotriazole-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, oxanilide-based UV absorbers, hindered amine-based UV absorbers, and benzoate-based UV absorbers. When the conductive polymer dispersion of this embodiment contains the above-mentioned additive, the content ratio can be appropriately determined depending on the type of additive, but for example, it can be 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.

[0063] ≪Method for manufacturing conductive laminates≫ A second aspect of the present invention is a method for manufacturing a conductive laminate, comprising the steps of obtaining a conductive polymer dispersion by the manufacturing method of the first aspect, and coating the conductive polymer dispersion onto at least a portion of the surface of a substrate.

[0064] [Base material] The substrate may be made of an insulating material or a conductive material. The shape of the substrate is not particularly limited, and examples include mainly flat shapes such as films and substrates. Examples of insulating materials include glass, synthetic resins, and ceramics. Examples of conductive materials include metals, conductive metal oxides, and carbon.

[0065] (Film substrate) When a film substrate is used as the aforementioned substrate, the conductive laminate becomes a conductive film. Examples of the film substrate include plastic films made of synthetic resins. Examples of the synthetic resins include ethylene-methyl methacrylate copolymer resin, ethylene-vinyl acetate copolymer resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacrylate, polycarbonate, polyvinylidene fluoride, polyarylate, styrene elastomer, polyester elastomer, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyimide, cellulose triacetate, and cellulose acetate propionate. From the viewpoint of improving adhesion between the film substrate and the conductive layer, the synthetic resin for the film substrate is preferably a polyester resin, and among these, polyethylene terephthalate is preferred.

[0066] The synthetic resin used for the film substrate may be amorphous or crystalline. The film substrate may be unstretched or stretched. The film substrate may be subjected to surface treatments such as corona discharge treatment, plasma treatment, or flame treatment in order to further improve the adhesion of the conductive layer.

[0067] The average thickness of the film substrate is preferably 5 μm to 500 μm, and more preferably 20 μm to 200 μm. If the average thickness of the film substrate is above the lower limit, it becomes less prone to tearing, and if it is below the upper limit, sufficient flexibility as a film can be ensured. The average thickness of the film substrate is the average of the measurements taken at 10 randomly selected locations.

[0068] (Glass substrate) Examples of glass substrates include alkali-free glass substrates, soda-lime glass substrates, borosilicate glass substrates, and quartz glass substrates. Since the presence of alkaline components in the substrate tends to reduce the conductivity of the conductive layer, alkali-free glass is preferred among the glass substrates. Here, alkali-free glass refers to a glass composition in which the content of alkaline components is 0.1% by mass or less of the total mass of the glass composition.

[0069] The average thickness of the glass substrate is preferably 100 μm to 3000 μm, and more preferably 100 μm to 1000 μm. If the average thickness of the glass substrate is above the lower limit, it becomes less prone to breakage, and if it is below the upper limit, it contributes to thinning the conductive laminate. The average thickness of the glass substrate is the average of the measurements taken at 10 randomly selected locations.

[0070] Methods for coating (applying) a conductive polymer dispersion to any surface of a substrate include, for example, methods using coaters such as gravure coaters, roll coaters, curtain flow coaters, spin coaters, bar coaters, reverse coaters, kiss coaters, fountain coaters, rod coaters, air doctor coaters, knife coaters, blade coaters, cast coaters, and screen coaters; methods using sprayers such as air sprayers, airless sprayers, and rotor dampening devices; and immersion methods such as dipping.

[0071] There are no particular restrictions on the amount of conductive polymer dispersion applied to the substrate, but considering uniform and even coating, conductivity, and film strength, the solid content should be approximately 0.01 g / m². 2 More than 10.0g / m 2 The following range is preferable.

[0072] A conductive layer can be formed by drying a coating film made of a conductive polymer dispersion applied to a substrate, removing at least a portion of the dispersion medium, and curing it. Methods for drying the coating include heat drying and vacuum drying. For heat drying, for example, methods such as hot air heating and infrared heating can be used. When applying heat drying, the heating temperature is set appropriately according to the dispersion medium used, but is usually within the range of 50°C to 200°C. Here, the heating temperature is the set temperature of the drying apparatus. Within the above heating temperature range, a suitable drying time is preferably 0.5 minutes to 30 minutes, and more preferably 1 minute to 15 minutes. After drying, UV irradiation may be performed to cure the binder components contained in the coating film.

[0073] The area in which the conductive layer is formed may be the entire surface of any surface of the substrate, or it may be only a part of it. In the case of a conductive film, it is preferable that a conductive layer of substantially uniform thickness is formed on substantially the entire surface of one or the other surface of the film substrate. If the conductive layer is formed on only a part of the surface of the substrate, for example, the conductive layer may be a fine conductive pattern such as a circuit or an electrode, or the area with the conductive layer and the area without the conductive layer may exist on the same surface and be roughly separated.

[0074] The average thickness of the conductive layer is preferably, for example, 10 nm to 100 μm, more preferably 20 nm to 50 μm, and even more preferably 30 nm to 30 μm. If the average thickness of the conductive layer is above the lower limit, high conductivity can be achieved, and if it is below the upper limit, the adhesion of the conductive layer to the substrate is further improved. The average thickness of the conductive layer is the average of the measurements taken at 10 randomly selected locations. [Examples]

[0075] (Manufacturing Example 1) Production of polystyrene sulfonic acid 206 g of sodium styrene sulfonate was dissolved in 1000 ml of deionized water, and while stirring at 80°C, 6.18 g of ammonium persulfate oxidizing agent solution, which had been previously dissolved in 10 ml of water, was added dropwise for 20 minutes, and this solution was stirred for 12 hours. To the obtained sodium polystyrene sulfonate solution, 1000 ml of sulfuric acid diluted to 10% by mass was added, and approximately 1000 ml of the solvent from the resulting polystyrene sulfonate solution was removed by ultrafiltration. Next, 2000 ml of deionized water was added to the remaining solution, and approximately 2000 ml of solvent was removed by ultrafiltration to wash the polystyrene sulfonate with water. This washing procedure was repeated six times. The water in the resulting solution was removed under reduced pressure to obtain a colorless solid of polystyrene sulfonic acid (PSS).

[0076] (Manufacturing Example 2) Preparation of a conductive polymer aqueous dispersion 14.2 g of 3,4-ethylenedioxythiophene and 36.7 g of polystyrene sulfonic acid were dissolved in 2000 ml of deionized water and mixed at 20°C. The resulting mixed solution was kept at 20°C, and while stirring, a solution of 29.64 g of ammonium persulfate and 8.0 g of ferric sulfate oxidation catalyst, dissolved in 200 ml of deionized water, was slowly added, and the mixture was stirred for 3 hours to allow the reaction to proceed. 2000 ml of deionized water was added to the resulting reaction solution, and approximately 2000 ml of the solution was removed by ultrafiltration. This procedure was repeated three times. Then, 200 ml of sulfuric acid diluted to 10% by mass and 2000 ml of deionized water were added to the obtained solution, and approximately 2000 ml of the solution was removed by ultrafiltration. Another 2000 ml of deionized water was added to this solution, and approximately 2000 ml of the solution was removed by ultrafiltration. This procedure was repeated three times. Furthermore, 2000 ml of deionized water was added to the obtained solution, and approximately 2000 ml of the solution was removed by ultrafiltration. This procedure was repeated five times to obtain a 1.2% by mass aqueous dispersion of polystyrene sulfonate-doped poly(3,4-ethylenedioxythiophene) (i.e., PEDOT-PSS aqueous dispersion).

[0077] (Example 1) To 10 g of the PEDOT-PSS aqueous dispersion at 25°C obtained in Production Example 2, 40 g of methanol at 25°C was added, and the temperature of the solution was measured. The temperature at this time was 32°C. After allowing the solution to stand until it reached the temperatures shown in Table 1, 50 g of isopropanol at 25°C was added to obtain a conductive polymer dispersion. This conductive polymer dispersion exhibited excellent wettability with respect to PET film.

[0078] <Rating> The conductive polymer dispersions obtained from each example were applied to polyethylene terephthalate film using a bar coater No. 8 to form a coated film. The coated film was then heat-dried at a drying temperature of 120°C for 1 minute, and the dispersion medium was removed to obtain a conductive film with a conductive layer formed on the surface. The surface resistance of this conductive film was measured using a resistivity meter (HIRESTA, manufactured by Mitsubishi Chemical Analytic Corporation) under an applied voltage of 10V. The measurement results are shown in Table 1. Note that "1.0E+06" in the table represents "1.0 × 10⁻⁶". 6 This means "[...]" and the same applies to the others.

[0079] [Table 1]

[0080] (Example 2) To 10 g of the PEDOT-PSS aqueous dispersion obtained in Production Example 2 at 25°C, 20 g of water was added and allowed to stand to reach 25°C. Then, 20 g of methanol at 25°C was added, and the temperature of the solution was measured. The temperature at this time was 34°C. After allowing the solution to stand until it reached the temperatures shown in Table 2, 50 g of isopropanol at 25°C was added to obtain a conductive polymer dispersion. This conductive polymer dispersion exhibited excellent wettability with respect to PET film. Using the conductive polymer dispersions obtained immediately from each example, conductive films were prepared in the same manner as in Example 1, and the surface resistance of the conductive layer was measured. The results are shown in Table 2.

[0081] [Table 2]

[0082] (Comparative Example 1) To 10 g of the PEDOT-PSS aqueous dispersion at 25°C obtained in Production Example 2, 50 g of isopropanol at 25°C was added, and the temperature of the solution was measured. The temperature at this time was 32°C. After allowing the obtained solution to stand until it reached 25°C, 40 g of methanol at 25°C was added to obtain a conductive polymer dispersion. This was immediately used to prepare a conductive film in the same manner as in Example 1.

[0083] (Comparative Example 2) To 10 g of the PEDOT-PSS aqueous dispersion at 25°C obtained in Production Example 2, 10 g of water at 25°C and 50 g of isopropanol at 25°C were added simultaneously, and the temperature of the solution was measured. The temperature at this time was 34°C. After allowing the obtained solution to stand until it reached 25°C, 30 g of methanol at 25°C was added to obtain a conductive polymer dispersion. This was immediately used to prepare a conductive film in the same manner as in Example 1.

[0084] [Table 3]

[0085] (Example 3) To 9.0 g of the conductive polymer dispersion obtained in Example 1-E, 1 g of Pluscoat RZ-105 (manufactured by Go-O Chemical Co., Ltd., water-dispersible polyester, solids content 30%) was added to obtain a conductive polymer dispersion. This conductive polymer dispersion exhibited excellent wettability with respect to the PET film. Using this dispersion, a conductive film was prepared in the same manner as in Example 1.

[0086] (Example 4) To 9.0 g of the conductive polymer dispersion obtained in Example 2-K, 1 g of Pluscoat RZ-105 (manufactured by Go-O Chemical Co., Ltd., water-dispersible polyester, solids content 30%) was added to obtain a conductive polymer dispersion. This conductive polymer dispersion exhibited excellent wettability with respect to the PET film. Using this dispersion, a conductive film was prepared in the same manner as in Example 1.

[0087] (Comparative Example 3) To 9.0 g of the conductive polymer dispersion obtained in Comparative Example 1, 1 g of Pluscoat RZ-105 (manufactured by Go-O Chemical Co., Ltd., water-dispersible polyester, solids content 30%) was added to obtain a conductive polymer dispersion. Using this, a conductive film was prepared in the same manner as in Example 1.

[0088] (Comparative Example 4) To 9.0 g of the conductive polymer dispersion obtained in Comparative Example 2, 1 g of Pluscoat RZ-105 (manufactured by Go-O Chemical Co., Ltd., water-dispersible polyester, solids content 30%) was added to obtain a conductive polymer dispersion. Using this, a conductive film was prepared in the same manner as in Example 1.

[0089] [Table 4]

[0090] From the above, it is clear that the conductive polymer dispersion obtained by adding methanol and then isopropanol according to the present invention can form a conductive layer with excellent conductivity. Since the conductive polymer dispersion contains methanol and isopropanol, it also exhibits good wettability to PET film. Surprisingly, the conductive layer prepared using the comparative example conductive polymer dispersion, which was obtained by adding isopropanol before methanol, exhibited inferior conductivity compared to the example. It is thought that the difference in the properties of the alcohol added earlier in the PEDOT-PSS aqueous dispersion had a significant impact on the dispersibility of PEDOT-PSS.

Claims

1. A conductive polymer-aqueous dispersion, in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed in water, is mixed with methanol to obtain a mixture, and then isopropanol is added to the mixture. A method for producing a conductive polymer dispersion, comprising the step of obtaining a conductive polymer dispersion in which the conductive composite is dispersed in a dispersion medium containing water, methanol, and isopropanol.

2. A method for producing a conductive polymer dispersion according to claim 1, wherein the isopropanol is added when the temperature of the mixture has fallen to a temperature at least 1°C lower than the temperature immediately after the addition of methanol.

3. The method for producing a conductive polymer dispersion according to claim 1, wherein the alcohol content in the conductive polymer-aqueous dispersion is 10% by mass or less relative to the total mass of the conductive polymer-aqueous dispersion.

4. A method for producing a conductive polymer dispersion according to claim 1, wherein the water content relative to the total mass of the dispersion medium is 10% by mass or more and 30% by mass or less.

5. A method for producing a conductive polymer dispersion according to claim 4, wherein the methanol content relative to the total mass of the dispersion medium is 15% by mass or more and 50% by mass or less.

6. A method for producing a conductive polymer dispersion according to claim 5, wherein the content of the isopropanol relative to the total mass of the dispersion medium is 30% by mass or more and 70% by mass or less.

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

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

9. A method for producing a conductive polymer dispersion according to claim 1, further comprising the step of adding a binder resin to the conductive polymer dispersion.

10. A method for manufacturing a conductive film, comprising the steps of: obtaining the conductive polymer dispersion by the manufacturing method described in any one of claims 1 to 9; coating the conductive polymer dispersion onto at least one surface of a film substrate; and drying the coated conductive polymer dispersion.

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