JP7311298B2 - Transparent conductive paint - Google Patents

Description

The present invention relates to a transparent conductive paint. More specifically, it relates to a transparent conductive paint with improved dispersibility of carbon nanomaterials.

Carbon nanomaterials are expected to be applied to conductive coating agents because of their high electrical conductivity, high drawability, low colorability, and excellent chemical stability. However, since carbon nanomaterials have a large aspect ratio and a coordinatively unsaturated structure, they have a strong intermolecular interaction and tend to aggregate. When the carbon nanomaterials are aggregated, they cannot exhibit their original properties such as conductivity and transparency. Therefore, it is required to improve the dispersibility of the carbon nanomaterials in the conductive coating agent.

In order to improve the dispersibility of carbon nanomaterials, ultrasonic dispersion treatment is known (Patent Document 1). Cavitation is generated by ultrasonic waves to disperse the carbon nanomaterials. Since the amount of cavitation generated depends on the temperature, it is easier to disperse at high temperatures. However, sonication is difficult to control, and excessive sonication tends to cut or break carbon nanomaterials, resulting in new active surfaces that are more susceptible to agglomeration. rice field. Such dispersions tend to aggregate, are inferior in coatability to substrates, and even when they are barely coatable, the conductivity and transparency of coating films are low, making it difficult to apply them to coating agents.

On the other hand, a technique for dispersing carbon nanomaterials under low temperature and mild conditions is known (Patent Document 2). Dispersion under mild conditions suppresses the cutting and breaking of nanocarbon materials, so dispersibility that can be applied to fields that do not require a high degree of transparency, such as applications where carbon nanomaterials are kneaded into resins. is obtained. However, in applications requiring high transparency such as transparent electrodes, even higher dispersibility is desired, and development of a transparent conductive paint that can be used in such applications has been desired.

JP 2006-16222 A International Publication No. 2015/015758

An object of the present invention is to provide a transparent conductive paint in which carbon nanomaterials are highly dispersed.

The present inventors have found that by repeating a strong dispersion process at high temperature and a cooling process that suppresses reaggregation, a carbon nanomaterial containing both high conductivity and high transparency required in the field of transparent conductive films can be obtained. They found that a transparent conductive paint can be obtained, and completed the present invention.

That is, the present invention provides the following steps (1) to (3):
(1) obtaining a mixture of (a) a carbon nanomaterial and (b) a dispersant;
(2) cooling the mixture from a dispersion temperature of 70° C. or less to a dispersion interrupting temperature of 40° C. or less, which is 10° C. or more lower than the dispersion temperature; and (3) performing the step (2) three times or more. It relates to a method for producing a transparent conductive coating, including.

In the method for producing a transparent conductive paint, (a) the carbon nanomaterial is preferably at least one selected from the group consisting of graphene, carbon nanotubes, and fullerenes.

In the method for producing a transparent conductive paint, the (b) dispersant preferably has an HLB of 12 or more.

In the method for producing a transparent conductive paint, the mixture in step (1) preferably further contains (c) an organic solvent.

In the method for producing a transparent conductive paint, the (c) organic solvent is preferably at least one selected from the group consisting of methanol, ethanol, and propanol.

The present invention also provides a transparent conductive paint containing (a) a carbon nanomaterial and (b) a dispersant, which is diluted 50 times by weight with a 50% aqueous solution of 2-propanol. It relates to a transparent conductive paint with a ratio of 20% or less.

In the transparent conductive paint, (a) the carbon nanomaterial is preferably at least one selected from the group consisting of graphene, carbon nanotubes, and fullerenes.

In the transparent conductive paint, (b) the dispersant preferably has an HLB of 12 or more.

The transparent conductive paint preferably further contains (c) an organic solvent.

In the transparent conductive paint, the (c) organic solvent is preferably at least one selected from the group consisting of methanol, ethanol, and propanol.

The transparent conductive paint obtained by the production method of the present invention has highly dispersed carbon nanomaterials and has both high conductivity and high transparency.

(1) Transparent conductive paint The present invention provides a transparent conductive paint containing (a) a carbon nanomaterial and (b) a dispersant, after being diluted 50 times by weight with a 50% aqueous solution of 2-propanol. A transparent conductive paint having a total light transmittance of 20% or less. Here, the concentration of 2-propanol is 100 parts by weight. This transparent conductive paint has a high dispersibility of carbon nanomaterials and has both high conductivity and high transparency required in the field of transparent conductive films.

(a) Carbon nanomaterials Examples of carbon nanomaterials include carbon nanotubes, graphene, and fullerene. These carbon nanomaterials may be used alone or in combination of two or more. The content of the carbon nanomaterial in the transparent conductive paint is not particularly limited, but is preferably 0.1 to 90% by weight, more preferably 0.2 to 70% by weight, more preferably 0.5% by weight, based on the total solid content of the transparent conductive paint. ~50% by weight is more preferred. In addition, when a coating composition containing a transparent conductive paint is applied onto a substrate by the method described below to produce a laminate, the amount is preferably 0.01 to 50.0 mg/m ² on the laminate, An amount of 0.1 to 10.0 mg/m ² is more preferred.

The type of carbon nanotube is not particularly limited, and carbon nanotubes manufactured by various known techniques such as an arc discharge method, a laser evaporation method, a chemical vapor deposition method (CVD method) can be appropriately selected and used. Any of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes and mixtures containing these in any ratio can be used. Single-walled carbon nanotubes are preferable because of their excellent conductivity.

The length of the carbon nanotubes is typically 1-2000 μm, preferably 5-1000 μm, more preferably 5-500 μm. If it exceeds 2000 μm, the carbon nanotubes tend to aggregate, cut, and break. Also, if the thickness is less than 1 μm, there is a tendency that a sufficient conductive path cannot be formed.

The diameter of carbon nanotubes is typically 0.1-50 nm, preferably 0.3-20 nm, more preferably 0.5-10 nm. If it exceeds 50 nm, the electrical conductivity may decrease. Also, it is difficult to produce carbon nanotubes of less than 0.1 nm.

(b) dispersant The dispersant is not particularly limited as long as it can disperse the carbon nanomaterial in water, but cationic dispersant, anionic dispersant, amphoteric dispersant, nonionic dispersant, polymeric dispersant Dispersants are included.

Cationic dispersants include alkylamine salts having an alkyl group of 8 to 22 carbon atoms such as stearylamine acetate, quaternary ammonium salts such as lauryltrimethylammonium chloride and hexadecyltrimethylammonium bromide.

Examples of anionic dispersants include sodium alkyl sulfates having 8 to 18 carbon atoms such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfate salts having 8 to 18 carbon atoms such as sodium polyoxyethylene lauryl ether sulfate, and deoxycholic acid. Examples include sodium, alkylbenzenesulfonates having an alkyl group of 8 to 18 carbon atoms such as sodium dodecylbenzenesulfonate, fatty acid salts, naphthalenesulfonic acid formalin condensates such as sodium salts of β-naphthalenesulfonic acid formalin condensates.

Amphoteric dispersants include alkylbetaines having alkyl groups of 8 to 22 carbon atoms and alkylamine oxides having alkyl groups of 8 to 18 carbon atoms.

Nonionic dispersants include polyoxyethylene alkyl ethers having alkyl groups of 1 to 20 carbon atoms, block copolymers composed of ethylene oxide and propylene oxide, and alkylphenol polyethylene glycols having alkyl groups of 1 to 20 carbon atoms. Examples include ethers, polyoxyalkylene derivatives such as polycarboxylate ethers having an alkylene group having 2 to 4 carbon atoms, and sorbitan fatty acid esters such as sorbitan tristearate.

Examples of polymeric dispersants include polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl butyral, hydroxycellulose, hydroxyalkylcellulose having an alkyl group having 1 to 8 carbon atoms, cellulose derivatives such as carboxymethylcellulose and carboxypropylcellulose, starch, gelatin, Examples include polymeric dispersants such as acrylic copolymers, polycarboxylic acids or derivatives thereof, polystyrenesulfonic acid or salts thereof.

Among these, polyvinylpyrrolidone, polyvinylbutyral, polyoxyalkylene derivatives, polystyrenesulfonic acid, cellulose derivatives, polycarboxylic acids, acrylic copolymers, and alkylbenzenesulfonates are preferable, and polyvinylpyrrolidone, polyvinylbutyral, polyoxyalkylene derivatives, poly Carboxylic acid, acrylic copolymers are more preferred. These dispersants may be used in combination of two or more. Further, a dispersant having one or more branched chains and having a branched chain molecular weight of 15 or more is preferable because the molecular chain spreads in all directions and dispersibility is enhanced.

The dispersant preferably has an HLB value of 12 or more, more preferably 14 or more, because it is excellent in dispersion stability. The HLB value can be calculated by the following calculation method.
Griffin method: [(molecular weight of hydrophilic portion) ÷ (total molecular weight)] × 20

The content of the dispersant in the transparent conductive paint is not particularly limited, but is preferably 0.1 to 99.9% by weight, more preferably 0.2 to 99% by weight, more preferably 0.2 to 99% by weight, based on the total solid content of the transparent conductive paint. 5 to 95% by weight is more preferred. If it is less than 0.1% by weight, the dispersibility will be insufficient, and if it exceeds 99.9% by weight, foaming will occur during the dispersion treatment, making it difficult to produce the coating composition.

The transparent conductive paint of the present invention has a total light transmittance of 20% or less after being diluted 50 times by weight with a 50% by weight 2-propanol aqueous solution. The total light transmittance was measured by diluting the transparent conductive paint 50 times by weight with a 50% by weight 2-propanol aqueous solution. A value calculated by comparing the value measured in a haze computer (manufactured by Suga Test Instruments Co., Ltd., HZ-2) with the measured value of a 50% by weight 2-propanol aqueous solution.

In the transparent conductive paint of the present invention, the dispersibility of the nanocarbon material is good, and the absorbance of the supernatant immediately after being subjected to centrifugation at 3500 rpm and 23° C. for 5 minutes is 90% of the absorbance before centrifugation. % or more. The ratio is more preferably 91% or higher, and even more preferably 92% or higher. Note that centrifugation for 5 minutes at 3500 rpm and 23° C. corresponds to standing for about one month. Absorbance can be measured at a wavelength of 647 nm regardless of whether the carbon nanomaterial is carbon nanotube, graphene, fullerene, or the like.

The solvent of the transparent conductive paint is not particularly limited as long as it can disperse the nanocarbon material, but water, alcohols such as methanol, ethanol, 2-propanol, 1-propanol; ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, etc. ethylene glycols; glycol ethers such as ethylene glycol monomethyl ether, 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 glycols such as propylene glycol, dipropylene glycol and tripropylene 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 Propylene glycol ether acetates such as glycol monomethyl ether acetate; ethers such as diethyl ether, diisopropyl ether, methyl-t-butyl ether, tetrahydrofuran; toluene, xylene (o-, m-, or p-xylene), hexane, heptane, etc. ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; halogens, organic solvents such as acetonitrile, mixed solvents of water and these organic solvents (hydrous organic solvent), a mixed solvent of two or more organic solvents, and the like. The organic solvent is preferably a water-miscible organic solvent, more preferably methanol, ethanol, propanol, or acetone, and still more preferably methanol, ethanol, or propanol, from the viewpoint of dispersion stability and coatability to the substrate. When a mixed solvent of water and an organic solvent is used, the concentration of the organic solvent is preferably 10-90% by weight, more preferably 20-80% by weight.

From the viewpoint of coatability and liquid stability, the solid content concentration in the transparent conductive paint is preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight, and more preferably 0.5 to 0.5% by weight. More preferably 5% by weight. This concentration can be adjusted by adjusting the amount of the solvent added to the transparent conductive paint.

(other ingredients)
The transparent conductive paint may further optionally contain a conductive polymer, a binder resin, an antioxidant, a viscosity adjuster, a pH adjuster, an antiseptic, an antifoaming agent, and the like. When these components are blended, they can be blended at any point, for example, during the process of manufacturing the transparent conductive paint described later, after manufacturing, or during the process of obtaining the coating composition described later.

When a conductive polymer is added to the transparent conductive paint, 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 containing at least one thiophene ring in the molecule is preferable because a highly conductive molecule can be easily formed by containing the thiophene ring in the molecule. The conductive polymer may form a complex with a dopant such as polyanion.

Among the conductive polymers containing at least one thiophene ring in the molecule, poly(3,4-disubstituted thiophene) is more preferable because of its excellent conductivity and chemical stability. Further, when the conductive polymer is poly(3,4-disubstituted thiophene) or a complex of poly(3,4-disubstituted thiophene) and polyanion (dopant), the low-temperature and short-time can form a conductor with a rough surface, and the productivity is also excellent. Note that the polyanion is a dopant for the conductive polymer, and the details thereof will be described later.

Poly(3,4-disubstituted thiophene) is particularly preferably poly(3,4-dialkoxythiophene) or poly(3,4-alkylenedioxythiophene). As poly(3,4-dialkoxythiophenes) or poly(3,4-alkylenedioxythiophenes), the following formula (I):

A cationic form of polythiophene consisting of repeating structural units represented by is preferred. Here, R ¹ and R ² independently represent a hydrogen atom or a C _1-4 alkyl group, or when R ¹ and R ² are bonded, a C _1-4 alkylene group represents Examples of the C _1-4 alkyl group include, but are not particularly limited to, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl and the like. . Further, when R ¹ and R ² are bonded, the alkylene group for C _1-4 is not particularly limited, but examples include methylene group, 1,2-ethylene group, 1,3-propylene group, 1, 4-butylene group, 1-methyl-1,2-ethylene group, 1-ethyl-1,2-ethylene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group and the like mentioned. Among these, a methylene group, a 1,2-ethylene group and a 1,3-propylene group are preferred, and a 1,2-ethylene group is more preferred. In the C _1-4 alkyl group and the C _1-4 alkylene group, part of the hydrogen atoms may be substituted. Poly(3,4-ethylenedioxythiophene) is particularly preferred as the polythiophene having a C _1-4 alkylene group.

The weight average molecular weight of the conductive polymer is preferably 500 to 100,000, more preferably 1,000 to 50,000, even more preferably 1,500 to 20,000.

Although the dopant is not particularly limited, polyanions are preferred. A polyanion forms a complex with a polythiophene (derivative) by forming an ion pair, and can stably disperse the polythiophene (derivative) in water. Examples of polyanions include, but are not limited to, carboxylic acid polymers (e.g., polyacrylic acid, polymaleic acid, polymethacrylic acid, etc.), sulfonic acid polymers (e.g., polystyrenesulfonic acid, polyvinylsulfonic acid, polyisoprene sulfonic acid, etc.). These carboxylic and sulfonic acid polymers are also copolymers of vinyl carboxylic and vinyl sulfonic acids with other polymerizable monomers such as acrylates, styrene, aromatic vinyl compounds such as vinyl naphthalene. can be Among these, polystyrene sulfonic acid is particularly preferred.

Polystyrene sulfonic acid preferably has a weight average molecular weight of 20,000 to 500,000, more preferably 40,000 to 200,000. If polystyrene sulfonic acid having a molecular weight outside this range is used, the dispersion stability of the polythiophene-based conductive polymer in water may be lowered. The weight average molecular weight is a value measured by gel permeation chromatography (GPC).

As the composite of the conductive polymer and the polyanion, a composite of poly(3,4-ethylenedioxythiophene) and polystyrenesulfonic acid is preferable because it has particularly excellent conductivity.

The conductivity of the conductive polymer is preferably 0.01 S/cm or more, more preferably 1 S/cm or more.

The content of the conductive polymer is preferably 5 to 2000 parts by weight, more preferably 10 to 1000 parts by weight, per 100 parts by weight of the solid content of the carbon nanomaterial.

When a binder resin is added to the transparent conductive paint, the binder resin described below as a component of the coating composition can be used as the binder resin. The content of the binder resin is not particularly limited, but is preferably 0.1 to 6000 parts by weight, preferably 0.1 to 5000 parts by weight, based on 100 parts by weight of the content of the carbon nanomaterial. It is more preferably 5 to 4000 parts by weight.

When a viscosity modifier is added to the transparent conductive paint, examples of the viscosity modifier include polyacrylic acid-based resins, cellulose ether resins, polyvinylpyrrolidone, polyurethane, carboxyvinyl polymer, and polyvinyl alcohol.

When the pH adjuster is added to the transparent conductive paint, examples of the pH adjuster include alkanolamines such as ammonia, ethanolamine, and isopropanolamine.

When an antifoaming agent is added to the transparent conductive paint, examples of the antifoaming agent include glycol-based compounds such as polyacetylene glycol, siloxane-based compounds such as organically modified polysiloxane, and emulsions in which polydimethylsiloxane is dispersed in water using an emulsifier. etc.

(2) Method for producing transparent conductive paint The method for producing the transparent conductive paint of the present invention comprises the following steps (1) to (3):
(1) obtaining a mixture of (a) a carbon nanomaterial and (b) a dispersant;
(2) cooling the mixture from a dispersion temperature of 70° C. or less to a dispersion interruption temperature of 40° C. or less, which is 10° C. or more lower than the dispersion temperature; and (3) performing the step (2) three or more times;
including.

In step (1), a mixture of (a) a carbon nanomaterial and (b) a dispersant is obtained. The solvent of the mixture is as explained as the solvent for the transparent conductive paint.

In addition, before the step (1), as a pretreatment, the carbon nanomaterial may be subjected to a high-speed stirring treatment. The high-speed stirring treatment is a dispersion treatment under mild conditions, and is not a treatment that accompanies breakage due to cavitation or fine pulverization due to collision of beads, unlike dispersion treatment using ultrasonic waves or a bead mill. The high-speed stirring treatment has the effect of loosening and loosening the dispersion of the aggregated carbon nanomaterials due to the high-speed rotation of the stirrer. By performing the high-speed stirring process before the dispersion process, the carbon nanomaterial can be dispersed more efficiently.

In step (2), the mixture obtained in step (1) is cooled from a dispersion temperature of 70°C or less to a dispersion interruption temperature of 40°C or less, which is 10°C or more lower than the dispersion temperature. The dispersing temperature is 70° C. or lower, preferably 65° C. or lower, more preferably 60° C. or lower, in order to disperse the carbon nanomaterials while preventing the carbon nanomaterials from being cut or destroyed. The dispersion temperature is preferably 10° C. or higher, more preferably 20° C. or higher, in order to disperse the carbon nanomaterial. The time for which the dispersion temperature is maintained is not particularly limited as long as the carbon nanomaterial can be dispersed, but is preferably 1 to 600 minutes, more preferably 2 to 400 minutes.

During the heat retention at the dispersion temperature, additional dispersion processing such as vibration mill, planetary mill, ball mill, bead mill, sand mill, jet mill, roll mill, homomixer, homogenizer, ultrasonic homogenizer, high pressure homogenizer, ultrasonic device, etc. Distributed processing may be performed. Dispersion processing may be batch type or continuous type.

The dispersion interruption temperature is required to be 10° C. or more lower than the dispersion temperature, preferably 15° C. or more lower than the dispersion temperature, more preferably 20° C. or more lower, further preferably 25° C. or more lower than the dispersion temperature. A specific dispersion interruption temperature is 40° C. or lower, preferably 30° C. or lower, in order to prevent cutting or breaking of the carbon nanomaterial. By cooling from the dispersion temperature to the dispersion interruption temperature, it is possible to prevent the carbon nanomaterial from being cut or destroyed.

The cooling rate from the dispersion temperature to the dispersion interruption temperature is not particularly limited, but is preferably 0.5° C./min or more, more preferably 1° C./min or more. The time for which the dispersion interruption temperature is maintained is not particularly limited, but is preferably 60 minutes or less, more preferably 30 minutes or less. During the cooling from the dispersion temperature to the dispersion interruption temperature, steps such as the addition and withdrawal of additional ingredients may be performed as long as the temperature remains below the dispersion temperature and above the dispersion interruption temperature.

In the step (3), the step (2) is further performed three times or more. Therefore, the step (2) is carried out a total of four times or more in the method for producing a transparent conductive paint of the present invention. By performing the step (2) four times or more in total, it is possible to achieve a high degree of dispersion of the carbon nanomaterials while preventing the carbon nanomaterials from being cut or destroyed. In step (3), the number of repetitions of step (2) is 3 or more, preferably 5 or more, and more preferably 7 or more. If the number of repetitions of the step (2) is 2 or less (the total number of times the step (2) is performed is 3 or less), the carbon nanomaterial cannot be sufficiently dispersed.

In the method for producing a transparent conductive coating material of the present invention, the dispersion temperature in each time of step (2) which is repeatedly performed may be the same or different as long as it is 70° C. or less. Similarly, the temperature at which dispersion is interrupted each time in step (2), which is repeated, may be the same or different as long as it is lower than the immediately preceding dispersion temperature by 10°C or more. When repeating step (2), the rate of temperature increase from the dispersion interruption temperature to the dispersion temperature is not particularly limited, but is preferably 0.5° C./min or more, more preferably 1° C./min or more. During the temperature rise from the dispersion interruption temperature to the dispersion temperature, as long as the temperature is maintained in a range lower than the dispersion interruption temperature and higher than the dispersion interruption temperature, steps such as addition and removal of additional components may be performed.

(3) Coating composition A coating composition can be obtained by mixing the transparent conductive paint of the present invention with a binder resin, a leveling agent, an organic solvent, and the like. The method of adding the binder resin, the leveling agent, the organic solvent, etc. is not particularly limited, and these components may be added to the transparent conductive paint simultaneously or separately. When added separately, the order of addition is not particularly limited.

The content of the transparent conductive paint in the ^coating composition is not particularly limited. More preferred is an amount of ~10.0 mg/m ² . If it is less than 0.01 mg/m ² , the ratio of carbon nanomaterials present in the laminate is reduced, and sufficient electrical conductivity may not be ensured. If it exceeds 50.0 mg/m ² , the proportion of the carbon nanomaterial in the laminate increases, which may adversely affect the strength and film formation properties of the coating film.

Although the binder resin is not particularly limited, it is preferably at least one selected from the group consisting of polyester resins, acrylic resins, polyurethanes, epoxy resins, alkoxysilane oligomers, polyolefin resins, and melamine resins. The reason for this is that the compatibility with other components in the coating composition is high, and the laminate formed using the coating composition containing these binders has good affinity for the substrate and good film-forming properties. Because there is These binders may be used alone or in combination of two or more.

The polyester resin is not particularly limited as long as it is a polymer compound obtained by polycondensation of a compound having two or more carboxyl groups in the molecule and a compound having two or more hydroxyl groups. Examples include polyethylene. Examples include terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and the like. These may be used independently and may use 2 or more types together.

Examples of acrylic resins include, but are not particularly limited to, (meth)acrylic resins, vinyl ester resins, and the like. These acrylic resins may be, for example, polymers containing, as constituent monomers, polymerizable monomers having acid groups such as carboxyl groups, acid anhydride groups, sulfonic acid groups, and phosphoric acid groups. and a copolymer of a polymerizable monomer having an acid group and a copolymerizable monomer. These may be used independently and may use 2 or more types together.

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). At least one of the (meth)acrylic monomer and the copolymerizable monomer should have an acid group.

Examples of (meth)acrylic resins include (meth)acrylic monomers having an acid group [(meth)acrylic acid, sulfoalkyl (meth)acrylate, sulfonic acid group-containing (meth)acrylamide, etc.] or Polymers, (meth)acrylic monomers optionally having an acid group, and other polymerizable monomers having an acid group [other polymerizable carboxylic acids, polymerizable polycarboxylic acids or anhydrides , vinyl aromatic sulfonic acid, etc.] and/or a copolymer with a copolymerizable monomer [e.g., (meth)acrylic acid alkyl ester, glycidyl (meth)acrylate, (meth)acrylonitrile, aromatic vinyl monomer, etc.] Polymers, other polymeric monomers having an acid group and (meth)acrylic copolymerizable monomers [e.g., (meth)acrylic acid alkyl esters, hydroxyalkyl (meth)acrylates, glycidyl (meth)acrylates, (meth)acrylonitrile, etc.], rosin-modified urethane acrylate, special modified acrylic resin, urethane acrylate, epoxy acrylate, urethane acrylate emulsion, and the like.

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

The polyurethane 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. Examples include ester/ether polyurethane, ether polyurethane, polyester polyurethane, Examples include carbonate-based polyurethanes and acrylic-based polyurethanes. These may be used independently and may use 2 or more types together.

Although the epoxy resin is not particularly limited, for example, bisphenol A type, bisphenol F type, phenol novolak type, polyfunctional type having many benzene rings, tetrakis(hydroxyphenyl)ethane type or tris(hydroxyphenyl)methane type. , biphenyl type, triphenolmethane type, naphthalene type, orthonovolak type, dicyclopentadiene type, aminophenol type, alicyclic epoxy resins, silicone epoxy resins, and the like. These may be used independently and may use 2 or more types together.

The alkoxysilane oligomer is, for example, a high molecular weight alkoxysilane formed by condensation of alkoxysilane monomers represented by the following formula (II), and a siloxane bond (Si—O—Si). Examples include oligomers having one or more in one molecule.
_SiR4 (II)
(Wherein, R is hydrogen, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, an alkyl group which may have a substituent, a phenyl group which may have a substituent. at least one of which is an alkoxy group having 1 to 4 carbon atoms or a hydroxyl group)

The structure of the alkoxysilane oligomer is not particularly limited, and may be linear or branched. As the alkoxysilane oligomer, the compound represented by the formula (II) may be used alone, or two or more of them may be used in combination. Although the weight average molecular weight of the alkoxysilane oligomer is not particularly limited, it is preferably greater than 152 and 4000 or less, more preferably 500 to 2500. Here, the weight average molecular weight is a value measured by gel permeation chromatography (GPC).

Examples of polyolefin resins include, but are not limited to, polyethylene, polypropylene, chlorinated polypropylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified chlorinated polypropylene. These may be used independently and may use 2 or more types together.

The content of the binder resin is not particularly limited, but is preferably 100 to 6000 parts by weight, more preferably 500 to 4000 parts by weight, per 100 parts by weight of the carbon nanomaterial. If the content of the binder is less than 100 parts by weight, the strength of the laminate produced from the coating composition may be weakened. The ratio of the material becomes relatively small, and sufficient electrical conductivity of the laminate may not be ensured.

As the leveling agent, the HLB value is preferably 10 or more, more preferably 12 or more, because the higher the hydrophilicity, the better the dispersing power in the water-organic solvent. The HLB value can be calculated by the following calculation method.
Griffin method: [(molecular weight of hydrophilic portion) ÷ (total molecular weight)] × 20

Specific leveling agents include polyester leveling agents, polyether leveling agents, fluorine leveling agents, silicone leveling agents, and acrylic leveling agents. Among these, a polyester-based leveling agent having an ester bond and a polyether-based leveling agent having an ether bond are preferable because they easily interact with the carbon nanomaterial and have a higher dispersing function in water-alcohol.

Polyester-based leveling agents include polyester-modified acrylic group-containing polydimethylsiloxane, polyester-modified polydimethylsiloxane, polyester polyol, and the like.

Examples of polyether-based leveling agents include cellulose ether; pullulan; polyethylene glycol; silicones such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyether ester-modified hydroxyl group-containing polydimethylsiloxane, polyether-modified acrylic group-containing polydimethylsiloxane, etc. Modified polyethers; polyglycerin; polyether polyols, polyoxyethylene-polyoxypropylene condensates, polyoxyethylene alkylphenyl ethers, alkyl ether derivatives such as lauryl alcohol alkoxylates, alkyl ether sulfates, and the like. These leveling agents may be used alone or in combination of two or more.

Examples of fluorine-based leveling agents include perfluoropolyether-modified polydimethylsiloxane, perfluoropolyester-modified polydimethylsiloxane, perfluorobutanesulfonic acid, fluorine-containing group/hydrophilic/lipophilic group-containing oligomers, and perfluoroalkyl group-containing carboxylic acids. acid salts, perfluoroalkyl group- and phosphoric acid group-containing phosphate esters, and the like. These leveling agents may be used alone or in combination of two or more.

Examples of silicone-based leveling agents include polysiloxane, reactive polysiloxane into which reactive groups such as amino groups, epoxy groups, hydroxyl groups, and carboxyl groups have been introduced, alkyl groups, ester groups, aralkyl groups, and phenyl groups. , non-reactive polysiloxane into which non-reactive groups such as polyether groups are introduced. These leveling agents may be used alone or in combination of two or more.

Examples of acrylic leveling agents include acrylic copolymers composed of silicone and acrylic. These leveling agents may be used alone or in combination of two or more.

Among these, polyester-based leveling agents with ester bonds and polyether-based leveling agents with ether bonds are likely to interact with carbon nanomaterials and have high performance in dispersing nanocarbon materials in water-alcohol. , more preferred. As the carbon nanomaterial, a polyester-based leveling agent is most preferable when graphene is used, and a polyether-based leveling agent is most preferable when carbon nanotubes are used.

As a leveling agent, the same substance as the dispersing agent can be used, but it is preferable to use a leveling agent having a lower HLB value than the dispersing agent.

The content of the leveling agent is not particularly limited, but is preferably 0.01 to 40% by weight, more preferably 0.1 to 20% by weight, based on the total solid content of the coating composition. More preferably ~10% by weight. When the content of the leveling agent is less than 0.01% by weight, the dispersion stability and substrate coatability tend to be insufficient, while when it exceeds 40% by weight, the film strength is adversely affected, There is a tendency for coating unevenness to occur.

The organic solvent has the function of increasing the affinity of the coating composition for the substrate. The organic solvent is not particularly limited, and examples include 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. , diethylene glycol monomethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether and other glycol ethers; ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate and other glycol ether acetates; propylene glycol, dipropylene glycol, tri Propylene glycols such as propylene 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 ethers such as propylene glycol monomethyl ether acetate Acetates; ethers such as diethyl ether, diisopropyl ether, methyl-t-butyl ether, tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; toluene, xylene (o-, m-, or p-xylene) , Hexane, heptane and other hydrocarbons: ethyl acetate, butyl acetate, ethyl acetoacetate, methyl orthoacetate, ethyl orthoformate and other esters: N-methylformamide, N,N-dimethylformamide, γ-butyrolactone, N- Amide compounds such as methylpyrrolidone; hydroxyls such as trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, catechol, cyclohexanediol, cyclohexanedimethanol, glycerin, etc. Group-containing compounds; compounds having a sulfo group such as dimethylsulfoxide; halogens, isophorone, propylene carbonate, acetylacetone, acetonitrile, mixed solvents of water and these organic solvents (hydrous organic solvents), mixtures of two or more organic solvents A solvent etc. are mentioned. From the viewpoint of dispersion stability of carbon nanomaterials, a mixed solvent of water and an organic solvent is preferable, a mixed solvent of water and alcohols is more preferable, and a combination of water and methanol, water and ethanol, or water and 2-propanol. is more preferred. It is also effective to add ethylene glycols, propylene glycols, amide compounds and the like to improve coating properties.

The organic solvent preferably does not remain in the laminate formed using the coating composition. In the present specification, there is no particular distinction between a material that completely dissolves all components of the coating composition (i.e., "solvent") and a material that disperses insoluble components (i.e., "dispersion medium"). , both are described as "solvent".

(other ingredients)
The coating composition may further contain cross-linking agents, catalysts, antifoaming agents, viscosity modifiers, pH modifiers, foaming agents and the like.

By adding a cross-linking agent, the thermosetting binder resin can be cross-linked and the antistatic performance can be improved. Examples of the cross-linking agent include, but are not limited to, melamine-based, polycarbodiimide-based, polyoxazoline-based, polyepoxy-based, polyisocyanate-based, and polyacrylate-based cross-linking agents. These cross-linking agents may be used alone or in combination of two or more. When the coating composition contains a cross-linking agent, its content is not particularly limited, but it is preferably 30% by weight or less, more preferably 20% by weight or less in the coating composition.

When the coating composition contains a thermosetting binder resin and a cross-linking agent, the catalyst for cross-linking the thermosetting binder resin is not particularly limited, and examples thereof include photopolymerization initiators and thermal polymerization initiators. be done.

When a conductive polymer is blended into the coating composition, the heat resistance and moist heat resistance of the antistatic layer can be improved by blending a water-soluble antioxidant. The water-soluble antioxidant is not particularly limited, and includes reducing water-soluble antioxidants, non-reducing water-soluble antioxidants, and the like.

When a water-soluble antioxidant is blended in the coating composition, the blending amount of the water-soluble antioxidant is preferably 0.001 to 1000 parts by weight, preferably 0.05, per 100 parts by weight of the solid content of the conductive polymer. ~500 parts by weight is more preferred, and 0.1 to 300 parts by weight is even more preferred.

(4) A laminate having a coating film can be obtained by applying the laminate coating composition onto at least one surface of a substrate. The coating composition may be formed by applying it directly to the base material, or may be formed by applying another layer such as a primer layer on the base material in advance and then coating it on the layer.

Examples of the material of the substrate include glass, polyethylene terephthalate (PET), polyethylene naphthalate, polyester resins such as modified polyester, polyethylene (PE) resin, polypropylene (PP) resin, polystyrene resin, cyclic olefin resin, and the like. Polyolefin resins, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polyether ether ketone (PEEK) resins, polysulfone (PSF) resins, polyether sulfone (PES) resins, polycarbonate (PC) resins, polyamide resins, Polyimide resins, acrylic resins, triacetyl cellulose (TAC) resins, and the like are included. These materials may be used alone or in combination of two or more.

The thickness of the substrate is not particularly limited, but preferably 10 to 10000 μm, more preferably 25 to 5000 μm. From the viewpoint of transparency, the total light transmittance of the base film is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more.

A coating film can be obtained by applying a coating composition onto at least one surface of a substrate and then heat-treating it. The method of applying the coating composition to at least one surface of the substrate is not particularly limited, and known methods can be used, such as roll coating, bar coating, dip coating, spin coating, and casting. , die coating method, blade coating method, bar coating method, gravure coating method, curtain coating method, spray coating method, doctor coating method, slit coating method, relief (letterpress) printing method, stencil (screen) printing method, lithography (offset) A printing method, an intaglio (gravure) printing method, a spray printing method, an inkjet printing method, a tampo printing method, or the like can be used.

Before applying the coating composition onto at least one surface of the substrate, the surface of the substrate may be subjected to a surface treatment in advance, if desired. Examples of surface treatment include corona treatment, plasma treatment, itro treatment, and flame treatment.

The heat treatment for forming the coating film is not particularly limited and may be performed by a known method, for example, using a blower oven, an infrared oven, a vacuum oven, or the like. If the coating composition contains a solvent, the solvent is removed by heat treatment.

The temperature condition of the heat treatment when forming the coating film is not particularly limited, but it is preferably 150°C or less, more preferably 50 to 140°C, and even more preferably 60 to 130°C. . If the heat treatment temperature exceeds 150° C., the material of the base material to be used is limited, and for example, the base material generally used for transparent electrode films such as PET film, polycarbonate film, and acrylic film cannot be used. The treatment time of the heat treatment is not particularly limited, but is preferably 0.1 to 60 minutes, more preferably 0.5 to 30 minutes.

Although the thickness of the coating film is not particularly limited, it is preferably 1 to 2000 nm, more preferably 2 to 1500 nm, even more preferably 5 to 1000 nm.

The surface resistivity of the coating film is not particularly limited, but is preferably 10 ² to 10 ¹² Ω/square, more preferably 10 ³ to 10 ¹¹ Ω/square, and 10 ⁴ to 10 ¹⁰ Ω/square. □ is more preferable.

Although the refractive index of the coating film is not particularly limited, it is preferably 1.4 to 1.7, more preferably 1.4 to 1.6.

The haze value of the laminate is not particularly limited, but is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less. If the haze value exceeds 5.0%, the transparency of the laminate may deteriorate. Since the haze value is preferably as small as possible, the lower limit is not particularly limited, but is, for example, 0.01%. A haze value can be measured based on JISK7136.

Although the total light transmittance of the laminate is not particularly limited, it is preferably 85% or more, more preferably 87% or more, and even more preferably 90% or more. If the total light transmittance is less than 85%, the transparency may be insufficient (defective appearance). In addition, the upper limit of the total light transmittance is 100%. The total light transmittance can be measured according to JIS K7136.

The laminate of the present invention can be suitably used as a conductive film that requires both high transparency and high conductivity. Such applications include packaging materials for semiconductors and electronic components, surface protective films, polarizing plate applications, electrophotographic recording materials, magnetic recording materials, transparent touch panels, electroluminescence displays, and flat panel displays such as liquid crystal displays. Transparent conductive films, antistatic films, masking tapes, removable labels, and the like, which are used, may be mentioned.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the following examples. Hereinafter, "%" means "% by weight" unless otherwise specified.

(1) Materials used (1-1) Base film/PET film (manufactured by Toray Industries, Inc., Lumirror T60)

(1-2) Carbon nanomaterials/carbon nanotubes (Zeon Nano Technology Co., Ltd., ZEONANO SG101, average length 300 μm, diameter about 4 nm)

(1-3) dispersant/nonionic dispersant (manufactured by BASF, Pluronic F108, HLB: 24 or higher)
- Nonionic dispersant (manufactured by Clariant, product name: Genapol PF 80, HLB: 19)
・ Polymeric dispersant (manufactured by Nippon Shokubai Co., Ltd., product name: polyvinylpyrrolidone K-30, HLB: 15)

(1-4) Leveling agent/polyether leveling agent (manufactured by Sanyo Chemical Industries, Ltd., product name: Emalmin 240, HLB: 16)

(1-5) Binder resin / acrylic resin (manufactured by Toagosei Co., Ltd., Jurimer FC-80, solid content 30%)

(2) Evaluation method (2-1) Total light transmittance of transparent conductive paint A transparent conductive paint is diluted 50 times by weight with a 50% by weight 2-propanol aqueous solution, and then the diluted solution is measured using quartz glass. It was placed in a cell (optical path length: 10 mm, optical path width: 30 mm) and placed in a haze computer (manufactured by Suga Test Instruments Co., Ltd., HZ-2) to measure the total light transmittance. The total light transmittance of a 50% by weight 2-propanol aqueous solution was used as a reference.

(2-2) Viscosity of Transparent Conductive Paint The transparent conductive paint was allowed to stand at 25° C. in a constant temperature bath for 30 minutes, and then measured for viscosity with a Brookfield viscometer (Brookfield viscometer BM: manufactured by Toki Sangyo Co., Ltd.).

(2-3) Surface resistivity of coating film The surface resistivity of the coating film immediately after film formation was selected and evaluated from the following methods according to the surface resistivity and the measurable range of the apparatus.
When the surface resistivity is less than 1.0×10 ⁶ (Ω/□): Measured at an applied voltage of 10 V using an ESP probe Loresta GP MCP-T600 manufactured by Mitsubishi Chemical Corporation.
When the surface resistivity is 1.0×10 ⁶ (Ω/□) to 1.0×10 ⁸ (Ω/□): 10 V using a UA probe of Hiresta UP (MCP-HT450 type) manufactured by Mitsubishi Chemical Corporation was measured at an applied voltage of
When the surface resistivity exceeds 1.0×10 ⁸ (Ω/□): Measured at an applied voltage of 250 V using a UA probe of Hiresta UP (MCP-HT450 type) manufactured by Mitsubishi Chemical Corporation.

(2-4) Total light transmittance and haze of the laminate The total light transmittance and haze of the laminate immediately after production were measured according to JIS K7136 using a haze computer (manufactured by Suga Test Instruments Co., Ltd., HZ-2). .

(3) Preparation of transparent conductive paint (Example 1)
Carbon nanotubes, a nonionic dispersant (manufactured by BASF, product name: Pluronic F108, HLB: 24 or more), ethanol, and pure water were mixed in a glass beaker so as to obtain the parts by weight shown in Table 1. In addition, in Table 1, the compounding amount of the carbon nanotubes represents the solid content. This mixture was dispersed by sonication. The dispersion was maintained at the dispersion temperature shown in Table 2 while being ultrasonically treated, cooled to the dispersion interruption temperature shown in Table 2, and held at the temperature for 5 minutes. After that, heat retention at the dispersion temperature, cooling to the dispersion interruption temperature, and heat retention at the dispersion interruption temperature were repeated under the same conditions until the total number of times was as shown in Table 2. A conductive paint was obtained. Ultrasonic treatment was performed for 60 minutes at an output of 50 W and a frequency of 30 kHz using a batch-type ultrasonic homogenizer (manufactured by hielscher, product name "HP50H").

(Example 2)
Carbon nanotubes, a nonionic dispersant, ethanol, and pure water were mixed in a glass beaker so that the weight parts shown in Table 1 were obtained, and the mixture was dispersed by ultrasonic treatment to obtain a solid content of 1.1%. A transparent conductive paint was obtained. Ultrasonic treatment is performed under the conditions shown in Table 2 with temperature change, and a circulation type ultrasonic treatment method (manufactured by hielscher, product name "UIP2000hd", output 2000 W, frequency 20 kHz) is applied under the conditions shown in Table 2. The procedure was the same as in Example 1, except that it was carried out for a period of time.

(Example 3)
Carbon nanotubes, a nonionic dispersant, ethanol, and pure water were mixed in a glass beaker so that the weight parts shown in Table 1 were obtained, and the mixture was dispersed by ultrasonic treatment to obtain a solid content of 1.1%. A transparent conductive paint was obtained. The ultrasonic treatment was performed in the same procedure as in Example 1, except that the temperature was changed under the conditions shown in Table 2.

(Example 4)
Carbon nanotubes, a nonionic dispersant, an acrylic resin, ethanol, and pure water were mixed in a glass beaker so that the parts by weight shown in Table 1 were obtained, and the mixture was dispersed by ultrasonic treatment to obtain a solid content of 1.5. A 1% transparent conductive coating was obtained. The ultrasonic treatment was performed in the same procedure as in Example 1, except that the temperature was changed under the conditions shown in Table 2.

(Example 5)
A transparent conductive paint was produced using the same composition and conditions as in Example 1.

(Example 6)
Carbon nanotubes, a nonionic dispersant (manufactured by Clariant, product name: Genapol PF 80, HLB: 19) and pure water are mixed in a glass beaker so that the weight parts shown in Table 1 are obtained, and the mixture is subjected to ultrasonic waves. Dispersed by the treatment to obtain a transparent conductive paint with a solid content of 1.1%. The ultrasonic treatment was performed in the same procedure as in Example 1, except that the temperature was changed under the conditions shown in Table 2.

(Example 7)
Carbon nanotubes, polymer-based dispersant, ethanol, and pure water were mixed in a glass beaker so that the weight parts shown in Table 1 were obtained, and the mixture was dispersed by ultrasonic treatment to obtain a solid content of 1.1%. A transparent conductive paint was obtained. The ultrasonic treatment was performed in the same procedure as in Example 1, except that the temperature was changed under the conditions shown in Table 2.

(Comparative Examples 1 to 4)
Carbon nanotubes, a nonionic dispersant, ethanol, and pure water were mixed in a glass beaker so that the weight parts shown in Table 1 were obtained, and the mixture was dispersed by ultrasonic treatment to obtain a solid content of 1.1%. A transparent conductive paint was obtained. In Comparative Example 1, the temperature change was performed under the conditions shown in Table 2, and as the ultrasonic treatment for heat retention at the dispersion temperature, a circulation ultrasonic treatment method (manufactured by hielscher, product name “UIP2000hd”, output 2000 W, frequency 20 kHz) under the conditions shown in Table 2 for 2 hours. Comparative Examples 2 to 4 were carried out in the same procedure as in Example 1, except that the temperature change was carried out under the conditions shown in Table 2.

(4) Evaluation of Transparent Conductive Coating The appearance of the obtained transparent conductive coating was visually observed, and the dispersibility of carbon nanotubes was judged according to the following criteria. Table 2 shows the results.
After standing at 25 ° C. for 24 hours in a constant temperature bath, no aggregates were observed: ○
After standing at 25 ° C. for 24 hours in a constant temperature bath, aggregates were observed: ×
Further, the total light transmittance and viscosity of the transparent conductive paint were measured by the methods described above. Table 2 shows the results.

(5) Production of Coating Composition and Laminate In Examples 1 to 4, 6 to 7 and Comparative Examples 1 to 4, the transparent conductive paint was used as it was as the coating composition. In Example 5, 0.01 part by weight of a leveling agent and acrylic resin (Toagosei Co., Ltd. A coating composition was prepared by mixing 0.5 parts by weight of Jurimer FC-80 (solid content: 30%, manufactured by the company).

The coating composition was applied to one side of the substrate film by a bar coating method and dried at 120° C. for 2 minutes using a blower dryer to form a coating film, thereby obtaining a laminate. The film thickness of the coating film was adjusted to about 40 nm by appropriately selecting the solid content of the coating composition and the count of the bar coater.

Surface resistivity, total light transmittance, and haze of the obtained laminate were measured by the methods described above. Table 2 shows the results.

As shown in Table 2, the transparent conductive paints of Examples 1 to 7 had good dispersibility appearance immediately after production, all of the transparent conductive paints had a total light transmittance of 20% or less, and a carbon nanomaterial. was highly dispersed. In addition, since the laminates of Examples 1 to 7 are produced using a transparent conductive paint in which carbon nanomaterials are highly dispersed, the surface resistance is low, and the total light transmittance and haze measurement values show high transparency. was confirmed. In Example 4, the binder was blended in the transparent conductive paint, and in Example 5, the binder was blended in the coating composition. In both cases, the carbon nanomaterials were highly dispersed.

In Comparative Examples 1 to 4, the dispersibility of the carbon nanomaterial in the transparent conductive paint was low, and aggregates of the carbon nanomaterial settled down, so that the total light transmittance of the transparent conductive paint was 20% or more. rice field. Also, during coating with a bar coater, agglomerates of carbon nanomaterials were scraped off by the grooves of the bar coater, and a sufficient amount of carbon nanomaterials did not remain in the coating film, resulting in high surface resistivity. This is because, in Comparative Example 1, the temperature was not maintained at the dispersion interruption temperature, the dispersion temperature was too high in Comparative Example 2, and the dispersion interruption temperature was too high in Comparative Example 3, so that the carbon nanomaterial was cut or destroyed. As a result, it is presumed that a new active surface was generated to facilitate aggregation. Further, in Comparative Example 4, the dispersion and the number of suspensions of dispersion were not sufficient, so it is presumed that the carbon nanomaterial was not sufficiently dispersed in the first place.

Claims (6)

The following steps (1) to (3):
(1) (a) carbon nanotubes,
(b) a nonionic dispersant or polymeric dispersant, and
(c) water or a mixed solvent of water and a water-miscible organic solvent
obtaining a mixture of
(2) cooling the mixture from a dispersion temperature of 70° C. or less to a dispersion interrupting temperature of 40° C. or less, which is 10° C. or more lower than the dispersion temperature; and (3) performing the step (2) three times or more. A method for producing a transparent conductive coating, comprising: 2. The method for producing a transparent conductive paint according to claim 1 , wherein (b) the dispersant has an HLB of 12 or higher. 3. The method for producing a transparent conductive paint according to claim 1 , wherein (c) the water-miscible organic solvent is at least one selected from the group consisting of methanol, ethanol and propanol. (a) carbon nanotubes ;
(b) a nonionic dispersant or polymeric dispersant, and
(c) water or a mixed solvent of water and a water-miscible organic solvent
A transparent conductive paint comprising
A transparent conductive paint having a total light transmittance of 20% or less after being diluted 50 times by weight with a 50% aqueous solution of 2-propanol. 6. The transparent conductive paint according to claim 5 , wherein (b) the dispersant has an HLB of 12 or higher. 6. The transparent conductive paint according to claim 4 , wherein (c) the water-miscible organic solvent is at least one selected from the group consisting of methanol, ethanol and propanol.