JP2020024916A - Transparent conductive laminate and method for producing transparent conductive laminate - Google Patents

Abstract

To provide a transparent conductive laminate having high conductivity and transparency.SOLUTION: A transparent conductive laminate has, on a base material, a conductive layer containing a carbon material and having a surface resistivity of 1×10-1×10Ω/sq, wherein, the content of a carbon material with a major axis of 10 μm or more and a minor axis of 2 μm or more is 10/cmor less.SELECTED DRAWING: None

Description

The present invention relates to a transparent conductive laminate and a method for manufacturing a transparent conductive laminate.

Carbon materials are known to exhibit high chemical stability in addition to being excellent in conductivity and thermal conductivity, and are expected to be excellent conductive materials in fields such as optical applications. However, since the carbon material has a large aspect ratio and a coordination unsaturated structure, the carbon material has a strong intermolecular interaction and tends to aggregate. Since properties such as conductivity and transparency cannot be sufficiently exhibited in a state where the carbon material is aggregated, it is required to enhance the dispersibility of the carbon material in the conductive paint. In order to enhance the dispersibility of the carbon material, for example, it is known to perform a dispersion process using ultrasonic waves.

However, even the above-mentioned dispersion treatment is insufficient for the market demand for high transparency in recent years. At present, in response to the demand for high transparency, a method of reducing the carbon material to make it highly conductive (Patent Document 1) or a method of separating and using only highly conductive carbon nanomaterial (Patent Document 2) However, special equipment and processes are required, and there are still problems in commercial production.

JP-A-2006-60646 Japanese Patent No. 6223767

An object of the present invention is to provide a transparent conductive laminate having high conductivity and transparency.

The present inventors have found that the number per unit area of a carbon material having a specific size (in the present specification, including agglomerates containing a carbon material as described later) greatly affects conductivity and transparency. A transparent conductive laminate having a conductive layer containing a carbon material on the substrate and having a surface resistivity of 1 × 10 ² to 1 × 10 ¹¹ Ω / sq, and having a major axis of 10 μm. A new finding is that a transparent conductive laminate characterized in that the carbon material having the above and a minor axis of not less than 2 μm is not more than 10 pieces / cm ² provides high conductivity and transparency. The present invention has been completed.

That is, the present invention relates to the following:
[1] A transparent conductive laminate having a conductive layer containing a carbon material and having a surface resistivity of 1 × 10 ² to 1 × 10 ¹¹ Ω / sq on a substrate,
A transparent conductive laminate characterized in that the content of a carbon material having a major axis of 10 μm or more and a minor axis of 2 μm or more is 10 pieces / cm ² or less.
[2] The transparent conductive laminate according to [1], wherein the haze value is 3% or less.
[3] The transparent conductive laminate according to [1] or [2], wherein the carbon material is at least one selected from the group consisting of graphene, fullerene, and carbon nanotube.
[4] The transparent conductive laminate according to any one of [1] to [3], wherein the content of the carbon material in the conductive layer is 50 mg / m ² or less.
[5] A conductive paint for forming a conductive layer in the transparent conductive laminate according to any one of [1] to [4].
[6] A display device including the transparent conductive laminate according to any one of [1] to [4].
[7] A light control device including the transparent conductive laminate according to any one of [1] to [4].
[8] The method for producing a transparent conductive laminate according to any one of [1] to [4], including a step of forming a conductive layer on a substrate using a conductive paint containing a carbon material.
[9] The method for producing a transparent conductive laminate according to [8], comprising a step of filtering the conductive paint containing a carbon material using a filter having a pore size of 1 to 20 μm before the step of forming the conductive layer.
[10] The method for producing a transparent conductive laminate according to [9], wherein the material of the filter is a polyolefin.
[11] A method for producing a conductive paint containing a carbon material,
When a conductive layer is formed by applying the conductive paint so that the content of the carbon material is 50 mg / m ² on a substrate, the conductive layer has the following conditions (a) to (c):
(A) the surface resistivity is 10 ² to 10 ¹¹ Ω / sq;
(B) A method for producing a conductive paint satisfying that the haze value is 3% or less; and (c) the content of a carbon material having a major axis of 10 μm or more and a minor axis of 2 μm or more is 10 particles / cm ² or less.
[12] The method for producing a conductive paint according to [11], wherein the carbon material is at least one selected from the group consisting of graphene, fullerene, and carbon nanotube.
[13] The method for producing a conductive paint according to [11] or [12], comprising a step of filtering the conductive paint using a filter having a pore size of 1 to 20 µm.
[14] The method for producing a conductive paint according to [13], wherein the material of the filter is a polyolefin.
[15] The method for producing a conductive paint according to any one of [11] to [14], comprising a step of subjecting the carbon material to a dispersion treatment beyond a minimum point of the surface resistivity.

According to the present invention, a transparent conductive laminate having high conductivity and transparency can be obtained.

<< transparent conductive laminate >>
First, the transparent conductive laminate of the present invention will be described.
The transparent conductive laminate of the present invention has a conductive layer containing a carbon material and having a surface resistivity of 1 × 10 ² to 1 × 10 ¹¹ Ω / sq on a substrate, and has a major axis of 10 μm or more and a minor axis. Is 2 μm or more, and the content of the carbon material is 10 pieces / cm ² or less.

<Substrate>
The material of the substrate is not particularly limited, and may be any of an inorganic substrate and an organic substrate. Among these, inorganic base materials are preferable because they are hardly affected by the solvent contained in the conductive paint and any solvent can be used. As the inorganic base material, alkali-free glass, borosilicate glass, aluminosilicate glass and the like are preferable, and alkali-free glass is more preferable. Organic base materials include cycloolefin polymer (COP), acrylic resin, polyethylene terephthalate (PET), amorphous PET, polyethylene naphthalate, polyester resin such as modified polyester, polyethylene resin (PE), and polypropylene resin (PP). , Polyolefin resins such as polystyrene resin and cyclic olefin resin, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polyetheretherketone resin (PEEK), polysulfone resin (PSF), polyethersulfone resin (PES) , Polycarbonate resin (PC), polyamide resin, polyimide resin, acrylic resin, triacetyl cellulose resin (TAC) and the like. Among these, cycloolefin polymer (COP), acrylic resin, polyethylene terephthalate (PET), polyvinyl alcohol resin, triacetyl cellulose resin (TAC) and the like are preferably used. These may be used alone or in combination of two or more.

The surface of the base material is subjected to various surface treatments such as corona treatment, plasma treatment, alkali treatment, excimer treatment, primer coating, degreasing treatment, surface roughening treatment for the purpose of facilitating adhesion and improving wettability. You may. In particular, it is preferable that the inorganic base material has been subjected to etching or a washing step with an alkaline solution in order to reduce the thickness and weight of the base material and to improve the wettability of the conductive paint to the base material.

In the case of an inorganic base material, the thickness of the base material is not particularly limited, but is preferably 10 mm or less, more preferably 0.01 to 50 mm, and still more preferably 0.01 to 1 mm.

In the case of an organic base material, the shape may be, for example, a film shape or a sheet shape. In the case of a film shape, the thickness is not particularly limited, but is preferably, for example, 10 to 200 μm, and more preferably 50 to 150 μm. In the case of a sheet shape, the thickness is not particularly limited, but is, for example, preferably 0.1 to 5 mm, and more preferably 0.2 to 1 mm.

<Conductive layer>
The conductive layer in the transparent conductive laminate of the present invention contains a carbon material and has a surface resistivity of 1 × 10 ² to 1 × 10 ¹¹ Ω / sq. By providing such a conductive layer, a transparent conductive laminate excellent in conductivity can be provided.

The conductive layer can be formed, for example, by applying a conductive paint containing a carbon material on a base material and then performing a heat treatment. The conductive paint may be applied directly on at least one surface of the substrate, or after providing another functional layer such as a primer layer on the substrate in advance, it may be applied on the functional layer. Good.
Examples of the resin used for the functional layer include a polyurethane resin, a polyester resin, an acrylic resin, an epoxy resin, and other general-purpose resins.

(Carbon material)
Examples of the carbon material include carbon nanotube, graphene, fullerene, and the like. These may be used alone or in combination of two or more.

The carbon nanotube is not particularly limited, and a carbon nanotube manufactured by an arc discharge method, a laser evaporation method, a chemical vapor deposition method (CVD method) or the like can be used. More specifically, a single-wall carbon nanotube, Any of double-walled carbon nanotubes, multi-walled carbon nanotubes, and mixtures thereof can be used. It is preferable that at least a single-walled carbon nanotube is included from the viewpoint of excellent conductivity.

The length of the carbon nanotube is preferably from 1 to 2000 μm, more preferably from 5 to 1000 μm, and still more preferably from 5 to 500 μm. When the length of the carbon nanotube is within the above range, the conductivity and the transparency are excellent when the conductive layer is used.

In the case of a single-walled carbon nanotube, the diameter of the carbon nanotube is preferably 0.5 to 20 nm, more preferably 1 to 10 nm. When the diameter of the carbon nanotube is within the above range, conductivity and transparency are excellent when the carbon nanotube is used as a conductive layer.

The content of the carbon material in the conductive paint is not particularly limited, but is preferably 0.1 to 40 parts by weight, more preferably 0.5 to 30 parts by weight, in 100 parts by weight of the solid content of the conductive paint. And more preferably 1 to 20 parts by weight. When the content of the carbon material is within the above range, the conductivity and the transparency are both compatible when the conductive layer is used, which is preferable.

(Dispersant)
The carbon material may be one that has been subjected to dispersion treatment in water or the like in advance using a dispersant. Examples of the dispersant include a cationic dispersant, an anionic dispersant, an amphoteric dispersant, a nonionic dispersant, and a polymer dispersant. These may be used alone or in combination of two or more. The dispersant preferably has an HLB value of 12 or more, more preferably 14 or more. The HLB value in the present specification can be calculated by the following equation:
Griffin method: HLB value = [(molecular weight of hydrophilic portion) ÷ (total molecular weight)] × 20

Examples of the cationic dispersant include alkylamine salts having an alkyl group having 8 to 22 carbon atoms such as stearylamine acetate, quaternary ammonium salts such as lauryltrimethylammonium chloride and hexadecyltrimethylammonium bromide. Can be

Examples of the anionic dispersant include polyoxyethylene alkyl ether sulfate having an alkyl group having 8 to 18 carbon atoms such as sodium alkyl sulfate having 8 to 18 carbon atoms such as sodium lauryl sulfate and sodium polyoxyethylene lauryl ether sulfate. Naphthalenesulfonate formalin such as ester salts, sodium deoxycholate, sodium dodecylbenzenesulfonate and other alkylbenzene sulfonates having an alkyl group having 8 to 18 carbon atoms, fatty acid salts, and sodium salts of β-naphthalenesulfonic acid formalin condensate And condensates.

Examples of the amphoteric dispersant include an alkyl betaine having an alkyl group having 8 to 22 carbon atoms, an alkylamine oxide having an alkyl group having 8 to 18 carbon atoms, and the like.

Examples of the nonionic dispersant include polyoxyethylene alkyl ether having an alkyl group having 1 to 20 carbon atoms, a block copolymer composed of ethylene oxide and propylene oxide, and alkylphenol having an alkyl group having 1 to 20 carbon atoms. Examples thereof include polyoxyalkylene derivatives such as polyethylene glycol ether, polycarboxylate ether having an alkylene group having 2 to 4 carbon atoms, and sorbitan fatty acid esters such as sorbitan tristearate.

Examples of the polymer dispersant include polyvinyl pyrrolidone, polyvinyl alcohol, hydroxy cellulose, hydroxyalkyl cellulose having an alkyl group having 1 to 8 carbon atoms, carboxymethyl cellulose, cellulose derivatives such as carboxypropyl cellulose, starch, gelatin, acrylic Polymer dispersants such as copolymers, polycarboxylic acids or derivatives thereof, and polystyrene sulfonic acids or salts thereof.

Among them, polyvinylpyrrolidone, polyoxyalkylene derivative, polystyrenesulfonic acid, cellulose derivative, polycarboxylic acid, acrylic copolymer, and alkylbenzenesulfonic acid salt are preferable, and polyvinylpyrrolidone, polyoxyalkylene derivative, polycarboxylic acid, acrylic copolymer Is preferred because the dispersibility of the carbon material becomes better. Further, a dispersant having one or more branched chains and a branched chain having a molecular weight of 15 or more is preferable because the molecular chains spread in all directions and the dispersibility of the carbon material becomes higher.

The addition amount of the dispersant is preferably from 0.01 to 100 parts by weight, and more preferably from 0.2 to 40 parts by weight based on 1 part by weight of the carbon material from the viewpoint of compatibility between the dispersibility and the transparency. And more preferably 0.5 to 10 parts by weight.

By dispersing the carbon material in water in the presence of the dispersant, the carbon material and the dispersant interact with each other to obtain a conductive paint in which the carbon material is well dispersed in water.

<Binder resin>
The conductive paint may include a binder resin in order to increase the strength of the conductive paint. Although it does not specifically limit as a binder resin, For example, acrylic resin, polyester resin, urethane resin, melamine, silicate resin, titanate resin, aluminate resin, etc. are mentioned. These may be used alone or in combination of two or more. In particular, in terms of strength, transparency, and durability, it is preferable to include at least a silicate resin or a melamine resin.

The acrylic resin is not particularly limited, for example, a carboxyl group, an acid anhydride group, a sulfonic acid group, a polymer containing a polymerizable monomer having an acid group such as a phosphoric acid group as a constituent monomer, may be, for example, , A homopolymer or copolymer of a polymerizable monomer having an acid group, a copolymer of a polymerizable monomer having an acid group and a copolymerizable monomer, and the like. More specifically, ( (Meth) acrylic resins and the like.

The (meth) acrylic resin may be polymerized with a copolymerizable monomer as long as it contains a (meth) acrylic monomer as a main constituent monomer (for example, 50 mol% or more). It is sufficient that at least one of the (meth) acrylic monomer and the copolymerizable monomer has an acid group.

Examples of the (meth) acrylic resin include (meth) acrylic monomers having an acid group [(meth) acrylic acid, sulfoalkyl (meth) acrylate, sulfonic acid group-containing (meth) acrylamide, etc.) Polymer, (meth) acrylic monomer which may have an acid group, and another polymerizable monomer having an acid group [other polymerizable carboxylic acid, polymerizable polycarboxylic acid or anhydride , Vinyl aromatic sulfonic acid, etc.] and / or copolymerizable monomers [eg, alkyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylonitrile, aromatic vinyl monomer, etc.] Polymer, another polymer monomer having an acid group and a (meth) acrylic copolymerizable monomer [for example, (meth) acrylic acid alkyl ester, hydroxyalkyl (meth) acrylate, Rishijiru (meth) acrylate, copolymers of (meth) acrylonitrile, etc.], rosin-modified urethane acrylate, special modified acrylic resins, urethane acrylates, epoxy acrylates, and urethane acrylates emulsion and the like.

Among these (meth) acrylic resins, (meth) acrylic acid- (meth) acrylic acid ester polymers (such as acrylic acid-methyl methacrylate copolymer) and (meth) acrylic acid- (meth) acrylic acid Ester-styrene copolymers (such as acrylic acid-methyl methacrylate-styrene copolymer) are preferred.

The polyester resin is not particularly limited as long as it is a polymer compound obtained by polycondensing a compound having two or more carboxyl groups in the molecule and a compound having two or more hydroxyl groups, for example, polyethylene. Examples thereof include terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate.

The urethane resin is not particularly limited as long as it is a polymer compound obtained by copolymerizing a compound having an isocyanate group and a compound having a hydroxyl group, and examples thereof include ester ether polyurethane, ether polyurethane, and polyester polyurethane. , Carbonate-based polyurethane, acrylic-based polyurethane, and the like.

The silicate resin is, for example, an alkoxysilane obtained by condensing monomers of an alkoxysilane represented by the following general formula (1), and has one or more siloxane bonds (Si—O—Si) in one molecule. Oligomers and the like:
SiR ₄ (1)
[In the formula, R is hydrogen, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, an alkyl group which may have a substituent, or a phenyl group which may have a substituent. At least one is an alkoxy group or a hydroxyl group having 1 to 4 carbon atoms].
It is preferable that the silicate resin is obtained by condensing two or more molecules of the alkoxysilane represented by the general formula (1).
The structure of the alkoxysilane oligomer is not particularly limited, and may be linear or branched.

Silicon alkoxide acrylic resin, silicon alkoxide epoxy resin, silicon alkoxide vinyl resin, silicon alkoxide methacryl resin, silicon alkoxide thiol resin, silicon alkoxide amino resin, silicon alkoxide isocyanate resin, silicon alkoxide alkyl And a silicon alkoxide resin such as a silicon alkoxide resin having no functional group other than the silicon alkoxide group.

Although the content of the binder resin is not particularly limited, for example, it is preferably 20 to 99 parts by weight, more preferably 50 to 98 parts by weight, and more preferably 60 to 95 parts by weight in 100 parts by weight of the solid content of the conductive paint. More preferably, it is even more preferably 70 to 90 parts by weight. When the content of the binder resin is within the above range, the film strength and the conductivity when the conductive layer is formed are improved.

(Leveling agent)
The conductive paint preferably contains a leveling agent in order to increase the affinity for the substrate. By adding the leveling agent, it is possible to suppress the occurrence of repelling and unevenness when forming the conductive layer. The leveling agent also contributes to the improvement of the dispersion stability of the conductive paint, and the conductive layer formed of the conductive paint containing the leveling agent has good transparency and conductivity. As the leveling agent, one having a higher hydrophilicity does not hinder the dispersion of the carbon material, so that the HLB value is preferably 10 or more, and more preferably 12 or more. Further, it is preferable that the carbon material has higher affinity for the hydrophobic carbon material than the dispersant, and therefore, it is preferable that the carbon material has higher hydrophobicity than the dispersant.

Specific leveling agents include polyether-based leveling agents, siloxane-based leveling agents, fluorine-based leveling agents, polyester-based leveling agents, silicone-based leveling agents, and acrylic-based leveling agents. These may be used alone or in combination. Among these, polyester-based leveling agents having an ester bond and polyether-based leveling agents having an ether bond are preferable because they easily interact with the carbon material and do not hinder the dispersion of the carbon material in water-alcohol.

Examples of the polyester-based leveling agent include polyester-modified acrylic group-containing polydimethylsiloxane, polyester-modified polydimethylsiloxane, and polyester polyol.

Polyether-based leveling agents include cellulose ether; pullulan; polyethylene glycol: silicone such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyetherester-modified hydroxyl-containing polydimethylsiloxane, and polyether-modified acryl-containing polydimethylsiloxane. Modified polyether; polyglycerin; polyether polyol, polyoxyethylene-polyoxypropylene condensate, polyoxyethylene alkylphenyl ether, alkyl ether derivatives such as lauryl alcohol alkoxylate, and alkyl ether sulfate.

Perfluoropolyether-modified polydimethylsiloxane, perfluoropolyester-modified polydimethylsiloxane, perfluorobutanesulfonic acid, fluorine-containing / hydrophilic / lipophilic group-containing oligomer, perfluoroalkyl group-containing carboxylic acid Acid salts and phosphoric acid esters containing a perfluoroalkyl group / phosphate group.

Examples of the silicone-based leveling agent include, in addition to polysiloxane, a reactive polysiloxane into which a reactive group such as an amino group, an epoxy group, a hydroxyl group, and a carboxyl group is introduced, and an alkyl group, an ester group, an aralkyl group, and a phenyl group. And non-reactive polysiloxanes into which non-reactivity such as polyether groups are introduced.

Examples of the acrylic leveling agent include an acrylic copolymer composed of silicone and acrylic.

The content of the leveling agent is not particularly limited, but is preferably 0.01 to 40 parts by weight, more preferably 0.1 to 20 parts by weight, and more preferably 0.1 to 20 parts by weight based on the whole solid content of the conductive paint. More preferably, it is 10 parts by weight. When the content of the conductive paint is within the above range, the applicability of the base material, the dispersion stability, and the film strength as a conductive layer are improved.

(solvent)
The conductive paint may contain a solvent in order to increase the affinity for the substrate. The solvent is not particularly limited and includes, for example, alcohols such as methanol, ethanol, 2-propanol and 1-propanol; ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol; ethylene glycol monomethyl ether; Glycol ethers such as diethylene glycol monomethyl ether, ethylene glycol diethyl ether and diethylene glycol dimethyl ether; glycol ether acetates such as ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether acetate; propylene glycol, dipropylene glycol and tripropylene Professionals such as glycol Propylene glycol ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, propylene glycol dimethyl ether and propylene glycol diethyl ether; propylene glycol ether acetates such as propylene glycol monomethyl ether acetate; diethyl Ethers such as ether, diisopropyl ether, methyl-t-butyl ether and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; toluene, xylene (o-, m- or p-xylene), hexane, heptane Hydrocarbons such as: ethyl acetate, butyl acetate, ethyl acetoacetate, Esters such as methyl orthoacetate and ethyl orthoformate: amide compounds such as N-methylformamide, N, N-dimethylformamide, γ-butyrolactone, N-methylpyrrolidone; trimethylene glycol, 1,4-butanediol, Hydroxyl group-containing compounds such as 5-pentanediol, 1,6-hexanediol, neopentyl glycol, catechol, cyclohexanediol, cyclohexanedimethanol, glycerin; compounds having a sulfo group such as dimethyl sulfoxide; halogens, isophorone, propylene In addition to organic solvents such as carbonate, acetylacetone, and acetonitrile, a mixed solvent of water and these organic solvents (aqueous organic solvent), a mixed solvent of two or more organic solvents, and the like can be given.

When an inorganic base material is used, among the above solvents, alcohols, ethers, acetates, ketones, alcohols and ethers from the viewpoint of dispersion stability of the carbon material and applicability to the base material. Mixed solvents of alcohols and acetates, mixed solvents of alcohols and ketones, mixed solvents of water and organic solvents, alcohols, mixed solvents of water and alcohols, and water A mixed solvent of ethers, a mixed solvent of water and acetates, a mixed solvent of water, alcohol, and ether, a mixed solvent of water, alcohol, and acetate, and a mixed solvent of water, alcohol, and ketone are more preferable. , A mixed solvent of water and an alcohol, a mixed solvent of water and an ether, and a mixed solvent of water and an acetate. By using these solvents, a highly hydrophobic binder resin can be blended in the conductive layer. It is also effective to add ethylene glycols, propylene glycols, amide compounds and the like in order to improve coatability.

When using an organic base material, among the above solvents, water and an organic solvent are used in view of the dispersion stability of the carbon material, the applicability to the base material, and the prevention of deterioration in transparency due to swelling and discoloration of the base material. A mixed solvent of water and alcohols, a mixed solvent of water and ethers, a mixed solvent of water and acetates is more preferable, and a mixed solvent of water and alcohols is more preferable. As the alcohol used for the mixed solvent of water and alcohols, methanol, ethanol, and 2-propanol are preferable. When combining water and alcohols, the alcohol ratio is preferably 20 to 99%, more preferably 30 to 97%, and still more preferably 40 to 96%. Further, similarly to the case of the inorganic base material, it is effective to add ethylene glycols, propylene glycols, amide compounds and the like for improving coating properties.

The content of the solvent is not particularly limited, but is preferably added so that the solid content of the conductive paint is 3% by weight or less, and more preferably 0.1 to 2% by weight. . In addition, when a solvent is added to the conductive paint, the ratio of water in the solvent contained in the conductive paint is preferably set to 1 to 70% by weight, and more preferably 3 to 65% by combining water and another solvent. And more preferably 4 to 60% by weight.

In the present specification, a material that completely dissolves all components of the conductive paint (that is, “solvent”) and a material that disperses insoluble components (that is, “dispersion medium”) are not particularly distinguished. Are all described as “solvents”.

(Other components)
The conductive paint may further contain a conductive polymer, a crosslinking agent, a catalyst, an antioxidant, an antifoaming agent, a rheology control agent, a neutralizing agent, a thickener, and the like.

Examples of the conductive polymer include polythiophene, polypyrrole, polyaniline, polyacetylene, polyphenylenevinylene, polynaphthalene, and derivatives thereof. These may be used alone or in combination of two or more. Among them, a conductive polymer including at least one thiophene ring in the molecule is preferable because a molecule having high conductivity is easily formed. The conductive polymer may form a complex with a dopant such as a polyanion.
The composite of the conductive polymer and the polyanion is preferably a composite of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid, since the composite is particularly excellent in conductivity.

The crosslinking agent is not particularly limited, and examples thereof include melamine-based, polycarbodiimide-based, polyoxazoline-based, polyepoxy-based, polyisocyanate-based, and polyacrylate-based crosslinking agents. These may be used alone or in combination of two or more.

The catalyst is not particularly limited, and includes, for example, a photopolymerization initiator, a thermal polymerization initiator, an acid, a base and the like. These may be used alone or in combination of two or more.

The thickness of the conductive layer is preferably from 1 to 500 nm, more preferably from 10 to 300 nm, even more preferably from 20 to 200 nm.

Surface resistivity of the conductive layer is preferably ^{1 × 10 2 ~1 × 10 11} Ω / sq, more preferably ^{1 × 10 2 ~5 × 10 10} Ω / sq, 1 × 10 2 ~ More preferably, it is 1 × 10 ¹⁰ Ω / sq.

Conductive layer, the content of the carbon material is preferably 50 mg / ^{m 2} or less, more preferably 0.1 to 50 mg / ^{m 2,} still to be 0.5~45mg / ^{m 2} More preferably, it is still more preferably 1 to 45 mg / m ² .

As described above, the conductive layer can be formed by applying a conductive paint to at least one surface of the base material and then performing a heat treatment. The coating method is not particularly limited, and examples thereof include a roll coating method, a bar coating method, a dip coating method, a spin coating method, a casting method, a die coating method, a blade coating method, a bar coating method, a gravure coating method, a curtain coating method, and a spraying method. Coating method, doctor coating method, slit coating method, letterpress printing method, stencil (screen) printing method, lithographic (offset) printing method, intaglio (gravure) printing method, spray printing method, inkjet printing method, tampo printing method Etc. can be used.

When applying a conductive paint to a large-area substrate, for example, a conductive layer is formed using a tank, a pump for sending liquid, a filter for removing foreign substances, and a coating device including a coating device. This is advantageous in terms of production efficiency.

The filter constituting the coating equipment is not particularly limited, but is preferably a filter having a pore size of 1 to 20 μm, more preferably 2 to 10 μm, and further preferably 2 to 5 μm.

The material of the filter is not particularly limited, for example, nylon, cellulose, a mixture of cellulose acetate and nitrocellulose, cellulose derivatives such as cellulose ester, polytetrafluoroethylene, polyvinylidene fluoride, Teflon, fluorine resin such as polyvinyl fluoride And polyolefins such as polypropylene and polyethylene, ceramics, metals, polycarbonates, glass, polyesters, polyamides, polysulfones, polyimides, polyvinyl chloride, polystyrene and perfluorosulfonate (carboxylic) acids. Of these, polyolefins are preferred. Depending on the material of the filter, the carbon material is adsorbed on the filter and the surface resistivity may be too high when the conductive layer is formed using a conductive paint. Since it is difficult to act, a conductive paint which can exhibit a sufficient surface resistivity even after being filtered may be obtained.

By forming a conductive layer using a coating facility equipped with such a filter, it is possible to perform a step of filtering the conductive paint with a filter before performing the step of forming the conductive layer. A conductive layer having excellent resistance can be obtained.

The heat treatment for forming the conductive layer is not particularly limited, and can be performed using, for example, a blowing oven, an infrared oven, a vacuum oven, or the like. When the conductive paint contains a solvent, the solvent is preferably removed by a heat treatment.

The temperature condition of the heat treatment for forming the conductive layer is preferably 200 ° C. or lower, more preferably 60 to 180 ° C., and further preferably 80 to 150 ° C.

The heat treatment time is preferably from 0.1 to 60 minutes, more preferably from 0.5 to 30 minutes.

The transparent conductive laminate of the present invention is characterized in that the content of the carbon material having a major axis of 10 μm or more and a minor axis of 2 μm or more is 10 / cm ² or less (10 / cm ² or less), preferably The number is 4 / cm ² or less, more preferably 3 / cm ² or less. Here, the carbon material having a major axis of 10 μm or more and a minor axis of 2 μm or more means, in addition to one molecule having the above-mentioned size, a carbon material or a carbon material and a component in another conductive paint are aggregated. Includes those that have become massive and have the above size. When the carbon material is in the shape of a plate, a needle, a bundle, or the like, the longer side (the length at which the distance between two points is the maximum) when the laminate is observed from the lamination direction is defined as the longer diameter. One has a shorter diameter.
In this specification, the major axis, minor axis, and number of carbon materials are measured and evaluated with an optical microscope as described in Examples below.

The haze value of the transparent conductive laminate of the present invention is not particularly limited, but is preferably 3% or less, more preferably 2% or less, and further preferably 0.6% or less. . When the haze value is 3% or less, the transparency of the laminate becomes good. The lower limit of the haze value is not particularly limited, but is preferably, for example, 0.01%.
The haze value in the present invention refers to a value measured according to JIS K7136.

<< Conductive paint >>
The above-described conductive paint is also one aspect of the present invention, and the transparent conductive laminate of the present invention can be manufactured by using the conductive paint of the present invention.
The conductive paint can be produced, for example, by performing a process of dispersing a carbon material in water or an organic solvent in the presence of a dispersant. The dispersion treatment can be performed using, for example, a vibration mill, a planetary mill, a ball mill, a bead mill, a sand mill, a jet mill, a roll mill, a homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, an ultrasonic device, or the like. In order to obtain a conductive paint capable of exhibiting high conductivity and transparency, it is preferable to perform the dispersion treatment using at least one of an ultrasonic homogenizer and a high-pressure homogenizer.

Usually, the carbon material can be subjected to the dispersion treatment under the condition that the surface resistivity is lowest when the conductive layer is formed immediately after the dispersion treatment without adding any components other than the dispersant (surface resistivity The minimum point), the addition of arbitrary components and the generation of a certain storage period after the production of the conductive paint, the carbon materials or the carbon material and other components are aggregated and formed into a lump to form a conductive layer. In such a case, transparency and conductivity are reduced. Considering these factors that lower the transparency and conductivity, when dispersing the carbon material, the condition of high strength exceeding the minimum point of the surface resistivity, when the optional component is added or the conductive paint Even when a certain storage period occurs after the production, a conductive paint having excellent transparency and conductivity can be obtained when the conductive layer is formed.
Here, the dispersion treatment under the condition exceeding the minimum point of the surface resistivity can be appropriately set based on the common technical knowledge in the field according to the treatment method and the treatment amount of the apparatus to be used.

Before the step of performing the dispersion treatment, the carbon material may be subjected to a high-speed stirring treatment as a pretreatment. The high-speed stirring treatment is a dispersion treatment under relatively lower strength than the dispersion treatment using an ultrasonic homogenizer or the like, and has an effect of loosening the aggregation of the carbon material by high-speed rotation of the stirring body. By performing the high-speed stirring before the dispersion, the dispersion of the carbon material can be performed more efficiently.

If agglomerates and the like (including those formed by agglomeration of the carbon materials or other components with each other) remain even after the carbon material is dispersed, centrifugation is performed and these coagulations are performed. Aggregates and the like may be removed, or these aggregates and the like may be removed using a filter. When removing these aggregates and the like using a filter, the above-described filter can be used.

As described above, in addition to the carbon material, the conductive paint may contain other optional components. For each of the optional components, the carbon material may be added in the process of dispersing the carbon material. May be added after.

<< Application >>
The transparent conductive laminate of the present invention can be applied to applications requiring high conductivity and transparency, and is particularly suitably used for display devices and light control devices.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to only these examples. In addition, "part" or "%" means "part by weight" or "% by weight", respectively, unless otherwise specified.

1. Materials used 1-1. Base material, alkali-free glass plate (Corning, EAGLE XG, haze 0.1%)
As the non-alkali glass plate, one subjected to an etching treatment and an alkali treatment was used. In the etching treatment, the glass substrate was washed with water and then immersed in an etching solution composed of 1% hydrofluoric acid, 5% hydrochloric acid, 2% sulfuric acid, and water, and the glass surface was chemically polished. Then, it was washed with water and dried with a dryer. In the alkali treatment, an aqueous potassium hydroxide solution was used to wash the surface of the glass substrate. Thereafter, the crow substrate was washed with water and dried with a dryer.
-PET film (Lumirror T60, 2.1% haze, manufactured by Toray Industries, Inc.)
・ Acrylic resin (PMMA) film (Sumitomo Chemical Co., Ltd., Technoroy S001G, haze 0.9%)
・ Triacetylcellulose film (Fujitack TJ25UL, manufactured by Fuji Film)

1-2. Conductive material
・ Single-walled carbon nanotube (SWCNT) aqueous dispersion 1 (manufactured by Meijo Nanocarbon Co., Ltd., SWNT dispersion, carbon nanotube concentration 0.1%, solid content 0.5%)
-Single-walled carbon nanotube (SWCNT) aqueous dispersion 2 (prepared in Production Example 1, carbon nanotube concentration 0.1%, solid content 0.5%)
-Single-walled carbon nanotube (SWCNT) aqueous dispersion 3 (manufactured in Production Example 2, carbon nanotube concentration 0.1%, solid content 0.5%)
-Double-walled carbon nanotube (DWCNT) aqueous dispersion (manufactured in Production Example 3, carbon nanotube concentration 0.1%, solid content 1.1%)
-Multi-walled carbon nanotube (MWCNT) (manufactured by Fuji Dye Co., Ltd., MWNT dispersion, carbon nanotube concentration 5%, solid content 8%)
-Graphene (H-5 aqueous dispersion, solid content 15%, manufactured by XG Science)

1-3. Leveling agent / polyether type (manufactured by Clariant, product name: Emulsogen LCN070, HLB: 13)
・ Fluorine (CAPSTONE FS-3100, manufactured by DuPont, 100% nonvolatile)
・ Siloxane (8029 Additive, manufactured by Dow Corning Toray)

1-4. Binder resin, tetraethoxysilicate (Tokyo Chemical Industry Co., Ltd.)
・ Polycondensate of tetraethoxysilicate (Ethylsilicate 40, manufactured by Colcoat Co., Ltd.)
Melamine (manufactured by DIC Corporation, Becamine M-3, solid content: 77%)
-Acrylic resin (manufactured by Toagosei Co., Ltd., Julimer FC-80, solid content 30%, glass transition temperature 50 ° C)
・ Urethane acrylate (urethane acrylate 8965, manufactured by Japan Yupika Co., Ltd.)

1-5. Catalyst, nitric acid (Fuji Film Wako Pure Chemical Industries, Ltd.)
・ Sulfuric acid (Fuji Film Wako Pure Chemical Industries, Ltd.)
・ Formic acid (Fuji Film Wako Pure Chemical Industries, Ltd.)
・ Dodecylbenzenesulfonic acid (DBS) (Fuji Film Wako Pure Chemical Industries, Ltd.)
・ Cumenesulfonic acid (CS) (manufactured by Teica Corporation, product name: Teica Tox 500)
T-Butylperoxy 2-ethylhexanoate (TBPO) (Lupelox 26, manufactured by Mitsubishi Chemical Corporation)

1-6. Filter / Polyolefin (PO) filter (Betapure AU0911120, pore size 1 μm, manufactured by 3M Corporation)
・ Polyolefin (PO) filter (Nippon Integris Co., Ltd., pore size 2.5 μm)
・ Polyolefin (PO) filter (Taiwan Grace Co., Ltd., pore size 5μm)
・ Polyolefin (PO) filter (Micro-Klean DPPPC-2-A, manufactured by 3M Co., Ltd., pore size: 10 μm)
・ Teflon (registered trademark) (PTFE) type filter (FPF-500, manufactured by Wintech Co., Ltd., pore size: 5 μm)
-Teflon (registered trademark) (PTFE) -based filter (FPF-045, manufactured by Wintech Co., Ltd., pore size 0.45 μm)

(Production Example 1) Preparation of Single-Walled Carbon Nanotube Aqueous Dispersion 2 Single-walled carbon nanotube (SWCNT) aqueous dispersion 1 was adjusted to 20 ° C., and then dispersed at 80 MPa using a high-pressure homogenizer (Starburst Mini manufactured by Sugino Machine Co., Ltd.). The treatment was performed and immediately cooled to 20 ° C. with a cooling pipe. The dispersion step and the cooling step were repeated 20 times to obtain a single-walled carbon nanotube aqueous dispersion 2 having a solid content of 0.5%. After each cooling step, a small amount was withdrawn. The dispersion was applied to glass using No. 16, and the surface resistivity of the coating film dried on a hot plate at 120 ° C. for 2 minutes was measured. After the third cooling step, the surface resistivity decreased most ( Conditions where the surface resistivity is at a minimum point), and thereafter, it was confirmed that the temperature gradually increased.

(Production Example 2) Preparation of Single-Walled Carbon Nanotube Aqueous Dispersion 3 Single-walled carbon nanotube (SWCNT) aqueous dispersion 1 was placed in a glass beaker, and was treated with an ultrasonic homogenizer (HP50H manufactured by Hielscher) at 50 W for 200 minutes at a frequency of 30 kHz. By performing dispersion treatment while maintaining the liquid temperature at 25 ° C., an aqueous single-walled carbon nanotube dispersion 3 having a solid content of 0.5% was obtained.
A small amount was withdrawn every 10 minutes during the dispersion process. The dispersion was applied to glass using No. 16, and the surface resistivity of the coating film dried on a hot plate at 120 ° C. for 2 minutes was measured. It was low (the condition that the surface resistivity was at the minimum point), and it was confirmed that the surface resistivity was gradually increased when the dispersion step was further extended.

(Production Example 3) Preparation of Double-Walled Carbon Nanotube Aqueous Dispersion 1 1 part by weight of double-walled carbon nanotubes (manufactured by Aldrich Co., product number 755168) having an average length of 10 μm and a diameter of about 4 nm, and sodium dodecylbenzenesulfonate as a dispersant 10 parts by weight (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 989 parts by weight of pure water are placed in a glass beaker, and subjected to a dispersion treatment at 50 W and a frequency of 30 kHz for 30 minutes by an ultrasonic homogenizer (HP50H, manufactured by Hielscher). Thus, a double-walled carbon nanotube aqueous dispersion 1 having a solid content of 1.1% was obtained.
A small amount was withdrawn every 5 minutes during the dispersion process. The dispersion was applied to glass using No. 16, and the surface resistivity of the coating film dried for 2 minutes on a hot plate at 120 ° C. was measured. It was low (the condition where the surface resistivity was the minimum point), and it was confirmed that the value obtained after 30 minutes was slightly higher.

2. Examples (Examples 1 to 16, Comparative Examples 1 to 5)
The carbon material dispersion, the binder resin, and the leveling agent were mixed at the weight ratio (solid content ratio) shown in Table 1. The conductive paint was prepared by diluting with a diluting solvent composed of water and / or various solvents shown in Table 1 so that the solid content ratio shown in Table 1 was obtained. The conductive paint was used by being filtered by passing through a filter described in Table 1, and was applied using a wire bar. The obtained coating film was dried at 120 ° C. for 5 minutes using a blow dryer to form a conductive layer, thereby obtaining a transparent conductive laminate. The thickness of the conductive layer was adjusted to the thickness shown in Table 1 by appropriately selecting the number of the wire bar. The performance of the conductive layer was evaluated by the method described below, and the results are shown in Table 1.

3. Evaluation method (size and number of carbon materials)
From the transparent conductive laminates obtained in Examples 1 to 16 and Comparative Examples 1 to 5, ten test pieces each of 5 cm × 5 cm square were prepared. Using an optical microscope, the size and the number of the carbon materials were observed in a range of 1 cm ² at the center of the test piece, and the average value of 10 test pieces was obtained.

(Surface resistivity (SR))
For the ten test pieces described above, the surface resistivity of the conductive layer was selected from the following methods according to the surface resistivity and the measurable range of the apparatus, and after measurement, the average value of the ten test pieces was determined.
When the surface resistivity is 1 × 10 ⁶ Ω / sq to 1 × 10 ⁸ Ω / sq: The measurement was performed at an applied voltage of 10 V using a UA probe of Hiresta UP (MCP-HT450 type) manufactured by Mitsubishi Chemical Corporation.
In the case where the surface resistivity exceeds 1 × 10 ⁸ Ω / sq: It was measured at an applied voltage of 250 V using a Hiresta UP (MCP-HT450 type) UA probe manufactured by Mitsubishi Chemical Corporation.

(Haze value)
With respect to the ten test pieces described above, the average value of the ten test pieces was determined after measurement using a haze computer HGM-2B manufactured by Suga Test Instruments Co., Ltd. in accordance with JIS K 7150.

(Thickness)
Using an atomic force microscope (manufactured by Shimadzu Corporation, SPM-9600) for the ten test pieces described above, the average value of the ten test pieces was determined.

(Theoretical carbon material content)
The content of the carbon material in the conductive layer was calculated by the following formula:
Carbon material theoretical content (mg / m ² ) = film thickness (μm) × weight percent of carbon material in conductive paint (solid content ratio)

As a result of the example, the haze value of the laminate was increased as the number of carbon materials having a major axis of 10 μm or more and a minor axis of 2 μm or more in the conductive layer was increased, and the transparency was deteriorated. A similar tendency was observed for the surface resistivity.

Claims (15)

A transparent conductive laminate having a conductive layer containing a carbon material on a substrate and having a surface resistivity of 1 × 10 ² to 1 × 10 ¹¹ Ω / sq,
A transparent conductive laminate characterized in that the content of a carbon material having a major axis of 10 μm or more and a minor axis of 2 μm or more is 10 pieces / cm ² or less. The transparent conductive laminate according to claim 1, having a haze value of 3% or less. The transparent conductive laminate according to claim 1, wherein the carbon material is at least one selected from the group consisting of graphene, fullerene, and carbon nanotube. The content of the carbon material in the conductive layer is 50 mg / m ² or less, the transparent conductive laminate according to claim 1. A conductive paint for forming a conductive layer in the transparent conductive laminate according to claim 1. A display device comprising the transparent conductive laminate according to claim 1. A light modulating device comprising the transparent conductive laminate according to claim 1. On the substrate, including a step of forming a conductive layer by a conductive paint containing a carbon material,
A method for producing the transparent conductive laminate according to claim 1. The method for producing a transparent conductive laminate according to claim 8, further comprising a step of filtering the conductive paint containing a carbon material using a filter having a pore size of 1 to 20 m before the step of forming the conductive layer. The method for producing a transparent conductive laminate according to claim 9, wherein the material of the filter is a polyolefin. A method for producing a conductive paint containing a carbon material,
When a conductive layer is formed by applying the conductive paint so that the content of the carbon material is 50 mg / m ² on a substrate, the conductive layer has the following conditions (a) to (c):
(A) the surface resistivity is 10 ² to 10 ¹¹ Ω / sq;
(B) A method for producing a conductive paint satisfying that the haze value is 3% or less; and (c) the content of a carbon material having a major axis of 10 μm or more and a minor axis of 2 μm or more is 10 particles / cm ² or less. The method according to claim 11, wherein the carbon material is at least one selected from the group consisting of graphene, fullerene, and carbon nanotube. The method for producing a conductive paint according to claim 11, further comprising a step of filtering the conductive paint using a filter having a pore size of 1 to 20 μm. The method for producing a conductive paint according to claim 13, wherein the material of the filter is a polyolefin. The method for producing a conductive paint according to any one of claims 11 to 14, comprising a step of dispersing the carbon material beyond a minimum point of the surface resistivity.