WO2015177963A1 - Coating method - Google Patents

Abstract

Provided is a coating method with which coating failures are inhibited, and transparent conductive films having uniform in-plane distributions of sheet resistance values can be produced. This coating method includes: a coating-liquid preparation step for preparing an aqueous coating liquid which includes metal nanowires and/or carbon nanotubes, and a solvent including water as the main solvent; and a coating step in which a die coater is used to coat a base material with the aqueous coating liquid. The viscosity of the aqueous coating liquid is 1-50 mPa∙s. The surface tension of the aqueous coating liquid is 20-60 mN/m. The capillary number (Ca) represented by formula (1), namely Ca=µU/σ, is not more than 0.03 (in formula (1), µ represents the viscosity (Pa∙s) of the aqueous coating liquid, U represents the coating speed (m/s) of the aqueous coating liquid, and σ represents the surface tension (N/m) of the aqueous coating liquid).

Description

Coating method Cross-reference to related applications

This application claims the priority of Japanese Patent Application No. 2014-104612 (filed on May 20, 2014), the entire disclosure of which is incorporated herein by reference.

The present invention relates to a coating method, and relates to a coating method in which an aqueous coating solution containing at least one of metal nanowires and carbon nanotubes is coated on a substrate using a die coater.

A transparent conductive film provided on the display surface of the display panel, and a transparent conductive film such as a transparent conductive film of an information input device arranged on the display surface side of the display panel, such as a transparent conductive film, includes indium tin oxide. Metal oxides such as (ITO) have been used. However, transparent conductive films using metal oxides are expensive to produce because they are sputtered in a vacuum environment, and cracks and delamination are likely to occur due to deformation such as bending and deflection. .

Therefore, instead of a transparent conductive film using a metal oxide, a transparent conductive film using metal nanowires or carbon nanotubes that can be formed by coating or printing and has high resistance to bending and bending has been studied. . Transparent conductive films using metal nanowires and carbon nanotubes are also attracting attention as next-generation transparent conductive films that do not use indium, which is a rare metal (see, for example, Patent Documents 1 and 2).

Conventionally, a coating solution such as a photoresist solution is applied by flat plate slit die coating (for example, Patent Documents 3 and 4).

However, for example, when a coating film having a wet coating thickness of about 20 μm is formed by coating using a flat plate slit die, the volume of the paint bead is reduced, so that the stability of the paint bead is often impaired. For this reason, coating defects such as coating stripes and coating leakage may occur on the coating film surface.
Further, when the coating liquid is an aqueous coating liquid whose main solvent is water, the surface tension of water with respect to a solvent system such as isopropyl alcohol (IPA) or ethanol (EtOH) is high. The wettability is poor, and coating defects such as coating repelling may occur.
Furthermore, when the aqueous coating liquid containing metal nanowires and / or carbon nanotubes is applied, the in-plane distribution of the sheet resistance value may become uneven due to poor coating.

As described above, in a coating method in which an aqueous coating solution containing metal nanowires and / or carbon nanotubes is applied using a die coater, coating failure is prevented and the in-plane distribution of sheet resistance is uniform. The development of a coating method that can produce a transparent conductive film has not yet been made, and it is possible to produce a transparent conductive film that prevents inadequate coating and makes the in-plane distribution of the sheet resistance value uniform. There is a strong demand for the development of coating methods that can be used.

Japanese Patent No. 4893867 Japanese Patent No. 5174229 JP-A-8-243476 Special Table 2007-518558

This invention makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, an object of the present invention is to provide a coating method capable of producing a transparent conductive film in which the coating failure is prevented and the in-plane distribution of the sheet resistance value is uniform.

As a result of diligent studies to achieve the above object, the present inventor uses a die coater for an aqueous coating solution containing at least one of metal nanowires and carbon nanotubes and a solvent containing water as a main solvent. In the coating step of coating on a substrate, (i) the viscosity of the aqueous coating solution is 1 mPa · s to 50 mPa · s, and (ii) the surface tension of the aqueous coating solution is 20 mN / m to 60 mN. (Iii) that the number of capillaries Ca is 0.03 or less, thereby preventing coating failure and producing a transparent conductive film having a uniform in-plane distribution of sheet resistance values. The headline, the present invention has been completed.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A coating liquid preparation step of preparing an aqueous coating liquid containing at least one of metal nanowires and carbon nanotubes and a solvent containing water as a main solvent, and the aqueous coating liquid using a die coater A coating step of coating on a substrate, wherein the aqueous coating solution has a viscosity of 1 mPa · s to 50 mPa · s, and the aqueous coating solution has a surface tension of 20 mN / second. The coating method is characterized in that it is m to 60 mN / m, and the capillary number Ca represented by the following formula (1) is 0.03 or less.
(Equation 1)
Ca = μU / σ (1)
(In the above formula (1), μ represents the viscosity (Pa · s) of the aqueous coating solution, U represents the coating speed (m / s) of the aqueous coating solution, and σ represents the aqueous coating solution.) (Represents the surface tension (N / m) of the coating solution.)
In the coating method according to <1>, an aqueous coating solution containing at least one of metal nanowires and carbon nanotubes and a solvent containing water as a main solvent is applied onto a substrate using a die coater. In the coating step, (i) the viscosity of the aqueous coating solution is 1 mPa · s to 50 mPa · s, (ii) the surface tension of the aqueous coating solution is 20 mN / m to 60 mN / m, iii) Capillary number Ca is 0.03 or less. As a result, it is possible to manufacture a transparent conductive film that prevents coating failure and makes the in-plane distribution of the sheet resistance value uniform.
<2> The coating method according to <1>, wherein a coating speed of the aqueous coating solution is 100 mm / sec or less.
In the coating method according to <2>, since the coating speed of the aqueous coating solution is 100 mm / sec or less, it is possible to prevent coating stripes and coating leakage.
<3> The ratio of the coating gap between the die coater and the substrate to the wet coating thickness of the aqueous coating solution (coating gap / wet coating thickness) is 1.5 to 4.5. The coating method according to <1> or <2>.
In the coating method according to <3>, the ratio of the coating gap between the die coater and the substrate to the wet coating thickness of the aqueous coating solution (coating gap / wet coating thickness) is 1. Since it is .5 to 4.5, it is possible to prevent coating streaks and coating leakage and to perform coating satisfactorily.
<4> The coating method according to any one of <1> to <3>, wherein the wet coating thickness of the aqueous coating solution is 3 μm to 20 μm.
In the coating method according to <4>, since the wet coating thickness of the aqueous coating solution is 3 μm to 20 μm, the coating can be performed satisfactorily and the in-plane distribution of the sheet resistance value is made uniform. A transparent conductive film can be manufactured.
<5> The coating method according to any one of <1> to <4>, wherein a slit gap of the die coater is 30 μm to 150 μm.
In the coating method according to <5>, since the slit gap of the die coater is 30 μm to 150 μm, the water-based coating liquid can be prevented from clogging in the die coater and the water-based coating can be prevented. Liquid dripping can be prevented.
<6> The coating method according to any one of <1> to <5>, wherein the dry coating thickness of the aqueous coating solution is 30 nm to 70 nm.
In the coating method according to <6>, since the dry coating thickness of the aqueous coating solution is 30 nm to 70 nm, a transparent conductive film having sufficient conductivity and transparency can be obtained.
<7> The coating method according to any one of <1> to <6>, wherein in the coating step, the coating temperature of the aqueous coating solution is 10 ° C. to 60 ° C.
In the coating method according to <7>, since the coating temperature of the aqueous coating solution is 10 ° C. to 60 ° C., the viscosity of the aqueous coating solution can be easily adjusted.

According to the present invention, it is possible to solve the conventional problems and achieve the object, and to manufacture a transparent conductive film in which the in-plane distribution of the sheet resistance value is prevented by preventing poor coating. The coating method which can be provided can be provided.

FIG. 1 is a schematic diagram for explaining a die coater used in the coating method of the present invention. FIG. 2 is a schematic diagram for explaining a calendar processing step (pressure treatment step) performed after the coating method of the present invention (No. 1). Drawing 3 is a mimetic diagram for explaining the calendar processing process (pressurization processing process) performed after the coating method of the present invention (the 2).

(Coating method)
The coating method of the present invention includes at least a coating liquid preparation step and a coating step, and further includes other steps appropriately selected as necessary.

<Coating liquid preparation process>
The coating liquid preparation step is a step of preparing an aqueous coating solution.

<< Water-based coating liquid >>
The aqueous coating solution contains at least one of metal nanowires and carbon nanotubes and a solvent, and further contains a transparent resin material (binder), a dispersant, and other components as necessary. It becomes.

The dispersion method of the aqueous coating liquid is not particularly limited and can be appropriately selected depending on the purpose. For example, stirring, ultrasonic dispersion, bead dispersion, kneading, homogenizer treatment, pressure dispersion treatment, etc. Are preferable.

The total amount of metal nanowires and carbon nanotubes in the aqueous coating solution is not particularly limited and can be appropriately selected according to the purpose. The mass of the aqueous coating solution is 100 parts by mass. In this case, the amount is preferably 0.01 parts by mass to 10.00 parts by mass.
When the total compounding amount of the metal nanowires and carbon nanotubes is less than 0.01 parts by mass, the basis weight (0.001 g) sufficient for the metal nanowires and / or carbon nanotubes in the finally obtained transparent conductive film. / M ² to 1.000 g / m ² ) may not be obtained, and if it exceeds 10.00 parts by mass, the dispersibility of the metal nanowires and / or carbon nanotubes may be deteriorated.

-Metal nanowires-
The metal nanowire is made of metal and is a fine wire having a diameter on the order of nm.
The constituent element of the metal nanowire is not particularly limited as long as it is a metal element, and can be appropriately selected according to the purpose. For example, Ag, Au, Ni, Cu, Pd, Pt, Rh, Ir, Examples include Ru, Os, Fe, Co, Sn, Al, Tl, Zn, Nb, Ti, In, W, Mo, Cr, Fe, V, Ta, and the like. These may be used individually by 1 type and may use 2 or more types together.
Among these, Ag and Cu are preferable in terms of high conductivity.

The average minor axis diameter of the metal nanowire is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably more than 1 nm and not more than 500 nm, and more preferably 10 nm to 100 nm.
When the average minor axis diameter of the metal nanowire is 1 nm or less, the conductivity of the metal nanowire deteriorates, and the transparent conductive film containing the metal nanowire may not function as a conductive film. If it exceeds, the total light transmittance and haze of the transparent conductive film containing the metal nanowires may deteriorate. On the other hand, when the average minor axis diameter of the metal nanowire is within the more preferable range, it is advantageous in that the transparent conductive film including the metal nanowire has high conductivity and high transparency.

The average major axis length of the metal nanowire is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably more than 1 μm and not more than 1000 μm, and more preferably 10 μm to 300 μm.
When the average major axis length of the metal nanowires is 1 μm or less, the metal nanowires are not easily connected to each other, and the transparent conductive film containing the metal nanowires may not function as a conductive film. The total light transmittance and haze of the transparent conductive film containing the metal nanowire may deteriorate, or the dispersibility of the metal nanowire in the aqueous coating solution used when forming the transparent conductive film may deteriorate. . On the other hand, when the average major axis length of the metal nanowire is within the more preferable range, it is advantageous in that the transparent conductive film including the metal nanowire has high conductivity and high transparency.
The average minor axis diameter and the average major axis length of the metal nanowires are the number average minor axis diameter and the number average major axis length that can be measured with a scanning electron microscope. More specifically, at least 100 metal nanowires are measured, and the projected diameter and projected area of each nanowire are calculated from an electron micrograph using an image analyzer. The projected diameter was the minor axis diameter. Further, the major axis length was calculated based on the following formula.
Long axis length = projected area / projected diameter The average minor axis diameter was an arithmetic average value of minor axis diameters. The average major axis length was the arithmetic average value of the major axis length.

Furthermore, the metal nanowire may have a wire shape in which metal nanoparticles are connected in a bead shape. In this case, the length of the metal nanowire is not limited.

The weight per unit area of the metal nanowires is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably ^{0.001g / m 2 ~ 1.000g / m} 2, 0.003g / m 2 ~ 0.3 g / m ² is more preferable.
When the basis weight of the metal nanowire is less than 0.001 g / m ² , the metal nanowire is not sufficiently present in the metal nanowire layer, and the conductivity of the transparent conductive film may be deteriorated. If it exceeds .000 g / m ² , the total light transmittance and haze of the transparent conductive film may deteriorate. On the other hand, when the basis weight of the metal nanowire is within the more preferable range, it is advantageous in that the conductivity of the transparent conductive film is high and the transparency is high.

-Metal nanowire network-
The metal nanowire network means a network structure formed by connecting a plurality of metal nanowires to each other in a network. The metal nanowire network is formed through a pressure treatment process described later and a heat curing treatment process described later.

-carbon nanotube-
There is no restriction | limiting in particular as said carbon nanotube, According to the objective, it can select suitably, The thing synthesize | combined by the conventional synthesis method may be sufficient, and a commercially available thing may be used.
There is no restriction | limiting in particular as the synthesis | combining method of the said carbon nanotube, According to the objective, it can select suitably, For example, an arc discharge method, a laser evaporation method, a thermal CVD method etc. are mentioned.
There is no restriction | limiting in particular as said carbon nanotube, According to the objective, it can select suitably, A single-walled carbon nanotube (SWNT) may be sufficient, and a multi-walled carbon nanotube (MWNT) may be sufficient. However, the single-walled carbon nanotube is preferable.
The carbon nanotube may be a mixture of metallic and semiconducting carbon nanotubes, or may be a selectively separated semiconducting carbon nanotube.

-Carbon nanotube network-
The carbon nanotube network means a network structure formed by connecting a plurality of carbon nanotubes in a network. The carbon nanotube network is formed through a pressure treatment step described later and a heat curing treatment step described later.

-solvent-
The solvent is not particularly limited as long as it contains water as a main solvent, and can be appropriately selected depending on the purpose. It may or may not contain a solvent other than water.
The solvent other than water is not particularly limited and may be appropriately selected depending on the intended purpose. For example, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, Examples thereof include alcohols such as tert-butanol; ketones such as cyclohexanone, cyclopentanone and anone; amides such as N, N-dimethylformamide (DMF); sulfides such as dimethyl sulfoxide (DMSO). These may be used individually by 1 type and may use 2 or more types together.

In order to suppress drying unevenness and cracks in the aqueous coating solution formed using the aqueous coating solution, a high boiling point solvent may be further added to the aqueous coating solution. Thereby, the evaporation rate of the solvent from the aqueous coating solution can be controlled.
The high boiling point solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, butyl cellosolve, diacetone alcohol, butyl triglycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl Ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol isopropyl A Le, dipropylene glycol isopropyl ether, tripropylene glycol isopropyl ether, methyl glycol, and the like.
These may be used individually by 1 type and may use 2 or more types together.

-Transparent resin material (binder)-
The transparent resin material (binder) is for dispersing the metal nanowires and / or the carbon nanotubes.
There is no restriction | limiting in particular as said transparent resin material (binder), According to the objective, it can select suitably, For example, a known transparent natural polymer resin, synthetic polymer resin, etc. are mentioned, Thermoplastic It may be a resin, or may be a heat (light) curable resin that is cured by heat, light, electron beam, or radiation. These may be used individually by 1 type and may use 2 or more types together.
The thermoplastic resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, nitrocellulose, chlorinated polyethylene, chlorine Polypropylene, vinylidene fluoride, ethylcellulose, hydroxypropylmethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, and the like.
The thermosetting (photo) curable resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include silicon resins such as melamine acrylate, urethane acrylate, isocyanate, epoxy resin, polyimide resin, and acrylic-modified silicate. And a polymer in which a photosensitive group such as an azide group or a diazirine group is introduced into at least one of a main chain and a side chain.

-Dispersant-
The dispersant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyvinyl pyrrolidone (PVP); amino group-containing compounds such as polyethyleneimine; sulfo groups (including sulfonates) and sulfonyl groups. , Sulfonamide group, carboxylic acid group (including carboxylate), amide group, phosphate group (including phosphate and phosphate ester), phosphino group, silanol group, epoxy group, isocyanate group, cyano group, vinyl group, A compound having a functional group such as a thiol group or a carbinol group, which can be adsorbed to a metal; These may be used alone or in combination of two or more.
The dispersant may be adsorbed on the surface of the metal nanowire or the carbon nanotube. Thereby, the dispersibility of the said metal nanowire or the said carbon nanotube can be improved.

In addition, when the dispersant is added to the aqueous coating solution, it is preferable to add the dispersant so as not to deteriorate the conductivity of the finally obtained transparent conductive film. Thereby, the said dispersing agent can be made to adsorb | suck to a metal nanowire and / or a carbon nanotube in the quantity which is the extent which the electroconductivity of a transparent conductive film does not deteriorate.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the intended purpose. For example, surfactants, viscosity modifiers, curing accelerators, plasticity, stabilizers such as antioxidants and sulfidizing agents, and the like. , Etc.

<Coating process>
The coating step is a step of coating the prepared aqueous coating solution on a substrate. Here, the aqueous coating solution is as described above.

The coating method is not particularly limited as long as it is a coating using a die coater, and can be appropriately selected according to the purpose.

<< Die coater >>
There is no restriction | limiting in particular as said die-coater, According to the objective, it can select suitably, For example, a closed type (close system) flat plate slit die as shown in FIG. 1 etc. are mentioned.
In FIG. 1, a flat plate slit die 1 includes a die head 2, a coating liquid supply pump (not shown) for supplying the coating liquid X to the die head 2, and a coating liquid tank (not shown) for storing the coating liquid. Z)). The coating liquid supplied to the die head 2 is applied onto the substrate 4 through the slits 3 formed in the die head 2. The base material 4 is placed on the transport table 5 and transported at a predetermined speed. In this case, the conveyance speed of the base material 4 becomes a coating speed.
In FIG. 1, W represents a slit gap (width of the slit 3), H represents a coating gap (distance between the lower surface of the die head 2 and the upper surface of the substrate 4), and h represents a coating liquid ( Coated film) X represents the wet coating thickness.
Coating liquid supply using a closed type coater such as the flat-plate slit die 1 allows temperature adjustment of the coating liquid compared to coating liquid supply using an open type coater (open system) such as a wire bar or applicator. As a result, the viscosity of the coating liquid can be easily adjusted.

-Coating gap-
The coating gap is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 μm to 200 μm, and more preferably 30 μm to 150 μm.
When the coating gap is less than 20 μm, meniscus formation may be insufficient, and when it exceeds 200 μm, coating stripes may occur. On the other hand, when the coating gap is within the more preferable range, it is advantageous in terms of meniscus formation at the coating wetted part.

-Wet coating thickness-
The wet coating thickness is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 3 μm to 20 μm, and more preferably 5 μm to 15 μm.
When the wet coating thickness is less than 3 μm, coating may be difficult, and when it exceeds 20 μm, the in-plane distribution of the sheet resistance value may be uneven. On the other hand, when the wet coating thickness is within the more preferable range, it is advantageous in terms of good coating and uniformity of in-plane distribution of sheet resistance value.

The ratio of the coating gap to the wet coating thickness (coating gap / wet coating thickness) is not particularly limited and may be appropriately selected depending on the intended purpose. 2.0 to 4.0 are more preferable.
When the ratio (coating gap / wet coating thickness) is less than 1.5, coating streaks and coating leakage may occur, and when it exceeds 4.5, coating becomes difficult. There is. On the other hand, when the ratio (coating gap / wet coating thickness) is within the more preferable range, it is advantageous in terms of prevention of coating streaks and coating leakage and good coating.

-Slit gap-
The slit gap is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30 μm to 150 μm, and more preferably 50 μm to 100 μm.
When the slit gap is less than 30 μm, the aqueous coating solution may be clogged in the die coater, and when the slit gap exceeds 150 μm, liquid dripping of the aqueous coating solution may occur. On the other hand, when the slit gap is within the more preferable range, it is advantageous from the viewpoint of clogging of the aqueous coating solution and prevention of dripping.

As conditions for coating using the die coater, there is no particular limitation as long as the number of capillaries is within a predetermined range, and the viscosity and surface tension of the aqueous coating liquid are within a predetermined range, depending on the purpose, Although it can select suitably, it is preferable that the temperature and coating speed of the said aqueous coating liquid are in a predetermined range.

<< Capillary number >>
The capillary number Ca is represented by the following formula (1).
(Equation 2)
Ca = μU / σ (1)
(In the above formula (1), μ represents the viscosity (Pa · s) of the aqueous coating solution, U represents the coating speed (m / s) of the aqueous coating solution, and σ represents the aqueous coating solution.) (Represents the surface tension (N / m) of the coating solution.)
The capillary number Ca is not particularly limited as long as it is 0.03 or less, and can be appropriately selected according to the purpose, but is preferably 0.005 to 0.03.
When the capillary number Ca exceeds 0.03, poor coating is caused and the in-plane distribution of the sheet resistance value becomes non-uniform. On the other hand, if the number of capillaries Ca is within the preferred range, it is advantageous in that a coating film can be prevented and a transparent conductive film having a uniform in-plane distribution of sheet resistance can be produced.

<< Viscosity of aqueous coating liquid >>
The viscosity of the aqueous coating solution is not particularly limited as long as it is 1 mPa · s to 50 mPa · s, and can be appropriately selected according to the purpose, but is preferably 10 mPa · s to 40 mPa · s.
When the viscosity of the aqueous coating solution is less than 1 mPa · s or more than 50 mPa · s, poor coating is caused and the in-plane distribution of the sheet resistance value is made non-uniform. On the other hand, when the viscosity of the aqueous coating liquid is within the preferred range, it is advantageous in that a coating film can be prevented and a transparent conductive film having a uniform in-plane sheet resistance value can be produced. It is.

<< Surface tension of aqueous coating liquid >>
The surface tension of the aqueous coating solution is not particularly limited as long as it is 20 mN / m to 60 mN / m, and can be appropriately selected according to the purpose, but is preferably 25 mN / m to 50 mN / m.
When the surface tension of the aqueous coating liquid is less than 20 mN / m or exceeds 60 mN / m, a coating failure is caused and the in-plane distribution of the sheet resistance value becomes non-uniform. On the other hand, if the surface tension of the aqueous coating liquid is within the preferred range, a coating failure can be prevented and a transparent conductive film having a uniform in-plane distribution of sheet resistance can be produced. It is advantageous.

<< Temperature of aqueous coating liquid >>
The temperature of the aqueous coating solution is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 ° C to 60 ° C, more preferably 20 ° C to 40 ° C.
If the temperature of the aqueous coating solution is less than 10 ° C or more than 60 ° C, the viscosity of the aqueous coating solution may not be easily adjusted. On the other hand, when the temperature of the aqueous coating liquid is within the more preferable range, it is advantageous in terms of ease of adjusting the viscosity of the aqueous coating liquid.

<< Coating speed >>
The coating speed usually means the conveyance speed of the substrate during coating.
There is no restriction | limiting in particular as said coating speed (The conveyance speed of the base material at the time of coating), Although it can select suitably according to the objective suitably, 100 mm / sec or less is preferable, 50 mm / More preferably, sec or less.
When the coating speed exceeds 100 mm / sec, coating stripes and coating leakage may occur. On the other hand, when the coating speed is within the more preferable range, it is advantageous in terms of preventing coating stripes and coating leakage.

<< Base material >>
There is no restriction | limiting in particular as said base material, Although it can select suitably according to the objective, The transparent base material comprised with the material which has transparency with respect to visible light, such as an inorganic material and a plastic material, is preferable. The transparent substrate has a film thickness required for a transparent electrode having a transparent conductive film. For example, a film (sheet) thinned to such an extent that flexible flexibility can be realized, or an appropriate amount It is assumed that the substrate has a film thickness sufficient to realize flexibility and rigidity.
There is no restriction | limiting in particular as said inorganic material, According to the objective, it can select suitably, For example, quartz, sapphire, glass, etc. are mentioned.
There is no restriction | limiting in particular as said plastic material, According to the objective, it can select suitably, For example, a triacetyl cellulose (TAC), polyester (TPEE), a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN), a polyimide (PI), polyamide (PA), aramid, polyethylene (PE), polyacrylate, polyether sulfone, polysulfone, polypropylene (PP), diacetyl cellulose, polyvinyl chloride, acrylic resin (PMMA), polycarbonate (PC), epoxy Known polymer materials such as resin, urea resin, urethane resin, melamine resin, and cycloolefin polymer (COP) can be used. When a transparent substrate is constituted using such a plastic material, the film thickness of the transparent substrate is preferably 5 μm to 500 μm from the viewpoint of productivity, but is not particularly limited to this range.

<< Transparent conductive film >>
The transparent conductive film is prepared, for example, by preparing an aqueous coating solution containing at least one of metal nanowires and carbon nanotubes and a solvent (aqueous coating solution preparation step), and preparing the prepared aqueous coating solution. Coating on the base material (coating process), drying and removing the solvent in the aqueous coating solution (drying process), heat-curing process (heat-curing process process), and then calendering (pressurization) It is obtained by performing (processing).

-Thickness of transparent conductive film (dry coating thickness)-
The thickness (dry coating thickness) of the transparent conductive film is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30 nm to 70 nm, and more preferably 40 nm to 60 nm.
If the thickness of the transparent conductive film is less than 30 nm, sufficient conductivity may not be obtained, and if it exceeds 70 nm, in addition to not forming a sufficient network of metal nanowires or carbon nanotubes, transparency May get worse. On the other hand, when the thickness of the transparent conductive film is in the more preferable range, it is advantageous in terms of forming a network of metal nanowires or carbon nanotubes.

<Drying process>
The drying step is a step of drying and removing the solvent in the aqueous coating solution. Here, the aqueous coating solution and the solvent are as described above.
There is no restriction | limiting in particular as said drying, According to the objective, it can select suitably, For example, drying by the hot air of a dryer, hotplate drying, oven drying, IR drying, etc. are mentioned.

<Heat curing process>
The heat curing process is a process for performing a heat curing process.
The heating temperature in the heat curing treatment is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 60 ° C to 140 ° C, more preferably 80 ° C to 120 ° C, and particularly preferably about 120 ° C. .
When the heating temperature in the heat curing treatment is less than 60 ° C., the time required for drying may become long and workability may deteriorate, and when it exceeds 140 ° C., the balance with the glass transition temperature (Tg) of the substrate The substrate may be distorted. On the other hand, when the heating temperature in the heat curing treatment is within the more preferable range or the particularly preferable temperature, it is advantageous in terms of forming a metal nanowire network.
The heating time in the heat curing treatment is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 minute to 30 minutes, more preferably 2 minutes to 10 minutes, and particularly preferably about 5 minutes. .
When the heating time in the heat curing treatment is less than 1 minute, drying may be insufficient, and when it exceeds 30 minutes, workability may be deteriorated. On the other hand, when the heating time in the heat curing treatment is within the more preferable range or the particularly preferable time, it is advantageous in terms of network formation and workability of metal nanowires or carbon nanotubes.

<Calendar processing step (pressure treatment step)>
The calendering process (pressurizing process) is a process of calendering (pressurizing) the transparent conductive film.
In the calendering process (pressurizing process), for example, as shown in FIGS. 2 and 3, a pressed body 30 including a base material 10 and a transparent conductive film 20 formed on the base material 10 is applied to a press roll ( It is sandwiched and pressed by a roll pair 60 composed of a first roll 40 and a back roll (second roll) 50.

There is no restriction | limiting in particular as a roll used for the said pressurization process, According to the objective, it can select suitably, For example, an elastic roll, a metal roll, etc. are mentioned.
The surface pressure, line width, pressurization (load), and conveyance speed in the pressurization process are appropriately adjusted according to the type of roll used in the pressurization process.
Moreover, in the said pressurization process, in order to pressurize a transparent conductive film, you may use a "nip roll" or a "pinch roll".

2 and 3, the press roll 40 and the back roll 50 may rotate the surface of the transparent conductive film 20 once or a plurality of times.

It may be heated as a post-treatment of the pressure treatment. The transparent conductive film is heated, for example, at 80 ° C. to 250 ° C. for 10 minutes or less, more preferably at 100 ° C. to 160 ° C. for 10 seconds to 2 minutes. The transparent conductive film can be heated to a temperature higher than 250 ° C. depending on the type of substrate, and can be heated to a temperature of 400 ° C. For example, the glass substrate can be heat-treated at a temperature in the range of 350 ° C. to 400 ° C. However, post-treatment at higher temperatures (eg, temperatures above 250 ° C.) may require the presence of a non-oxidizing atmosphere such as nitrogen or a noble gas.

The heating can be performed either online or offline. For example, in the off-line process, the transparent conductive film can be placed in an oven set at a predetermined temperature for a predetermined time. When the transparent conductive film is heated by such a method, the conductivity of the transparent conductive film can be improved.

When it is necessary to apply heat in the pressurizing process, the roll may be heated (roll temperature control). The roll is preferably heated to 30 ° C. to 200 ° C., more preferably 40 ° C. to 100 ° C.

<< Elastic Roll >>
The material of the elastic roll is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the main component is a chloroprene polymer rubber, acrylonitrile butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM). Such as rubber; resin; and the like. These may be used individually by 1 type and may use 2 or more types together.
Among these, rubber having high hardness and solvent resistance is preferable.
In addition, in the said pressurization process, when roll temperature control is required, it is preferable that the material of the said elastic roll is not rubber | gum but resin.

The diameter of the elastic roll is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30 mm to 1,000 mm, more preferably 40 mm to 500 mm, and particularly preferably 50 mm to 300 mm.
When the diameter of the elastic roll is less than 30 mm, it is difficult to wind the rubber around the metal roll, and it may be difficult to produce the elastic roll, and when it exceeds 1,000 mm, it may be difficult to handle the roll. . On the other hand, when the diameter of the elastic roll is within the more preferable range or the particularly preferable range, it is advantageous in terms of roll production and handling.

<< Metal roll >>
There is no restriction | limiting in particular as a metal of the said metal roll, According to the objective, it can select suitably, For example, common metals, such as stainless steel (SUS), are mentioned. Here, the metal may be subjected to, for example, hard chrome plating.
Among these, a metal with high workability and solvent resistance is preferable.

The diameter of the metal roll is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30 mm to 1,000 mm, more preferably 40 mm to 500 mm, and particularly preferably 50 mm to 300 mm.
If the diameter of the metal roll is less than 30 mm, it may be difficult to produce the roll, and if it exceeds 1,000 mm, handling of the roll may be difficult. On the other hand, when the diameter of the metal roll is within the more preferable range or the particularly preferable range, it is advantageous in terms of roll production and handling.

In the pressure treatment step, a metal roll having a diameter of less than 200 mm is preferably used as the press roll (first roll), and an elastic roll having a diameter of 200 mm or more is preferably used as the back roll (second roll).
In the pressure treatment step, the cushioning action is increased by using a metal roll having a diameter of less than 200 mm as the press roll (first roll) and using an elastic roll having a diameter of 200 mm or more as the back roll (second roll). Thus, the pressure can be suitably released.

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
<Preparation of silver nanowire ink (aqueous coating liquid) 1>
Silver nanowire ink (aqueous coating liquid) 1 was prepared with the following composition.
(1) Metal nanowire: Silver nanowire (manufactured by Seashell Technology, AgNW-25, average diameter 25 nm, average length 23 μm): compounding amount 0.050 part by mass (2) binder: hydroxypropylmethylcellulose (manufactured by Aldrich, Viscosity of 2% aqueous solution at 20 ° C. 80 cP to 120 cP (document value)): blending amount 0.125 parts by mass (3) solvent: (i) water: blending amount 89.825 parts by mass, (ii) ethanol: blending amount 10 .000 parts by mass

<Preparation of silver nanowire transparent conductive film>
A silver nanowire transparent conductive film was prepared by the following procedure.
First, the produced silver nanowire ink (aqueous coating liquid) 1 was applied onto a transparent substrate (PET: Toray Industries, U34, film thickness 125 μm) with a flat plate die coater manufactured by Daimon Co., Ltd. Thus, a silver nanowire coating film was formed. Here, the basis weight of the silver nanowires was set to about 0.01 g / m ² . Here, the coating conditions were as follows.
<< Coating conditions >>
(1) Slit gap of flat plate die coater: 50 μm
(2) Coating gap between flat plate die coater and transparent substrate: 30 μm
(3) Wet coating thickness of silver nanowire coating film: 15 μm
(4) Coating speed: 15mm / sec
(5) Water-based coating solution temperature: 25 ° C
(6) Viscosity of aqueous coating solution: 6 mPa · s
(7) Surface tension of aqueous coating solution: 45 mN / m
(8) Number of capillaries: 0.0020
Here, the wet coating thickness was calculated from the coating area and the coating liquid discharge liquid per unit time.

Next, in the atmosphere, hot air was applied to the coated surface with a drier to remove the solvent in the silver nanowire coating film by drying.
Thereafter, a heat curing treatment at 120 ° C. for 5 minutes was performed in an oven to produce a silver nanowire transparent conductive film.

<Pressure treatment of silver nanowire transparent conductive film>
Using the calendar processing apparatus (refer FIG.2 and FIG.3) provided with a cylindrical press roll (1st roll) and a back roll (2nd roll) with respect to the produced silver nanowire transparent conductive film, a calendar process is carried out. (Pressurizing treatment) was performed. At the time of calendering (pressure treatment), both the press roll (first roll) and the back roll (second roll) are made of steel (manufacturer name: Miyagawa Roller), and the pressure (load) is 4 kN. The conveyance speed was 1 m / min.

<Measurement of resistance value>
The resistance value of the silver nanowire transparent conductive film was measured as follows. The surface of the silver nanowire transparent conductive film is contacted with a measurement probe of a manual nondestructive resistance measuring device (Napson Co., Ltd., EC-80P), and any 12 on the surface of the transparent conductive film (silver nanowire layer) The resistance value was measured at each location, and the average value was taken as the resistance value. The resistance value was 118Ω / □. The measurement results are shown in Table 1A.

<Evaluation of resistance distribution>
The standard deviation σ was calculated using the values of any 12 locations measured in the measurement of the resistance value, and the resistance distribution of the silver nanowire transparent conductive film was evaluated according to the following evaluation criteria. The standard deviation σ was 7Ω / □. Table 1 shows the calculation results and the evaluation results.
<< Evaluation criteria >>
○: Standard deviation σ is less than 10 (σ <10)
Δ: Standard deviation σ is 10 or more and less than 20 (10 ≦ σ <20)
×: Standard deviation σ is 20 or more (20 ≦ σ)

<Evaluation of coating film appearance>
The appearance of the transparent conductive film was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
<< Evaluation criteria >>
○: No appearance defect due to coating ×: Defect due to coating (coating streaks, coating scraping, or coating repelling)

(Example 2)
In Example 1, instead of setting the coating speed to 15 mm / sec and setting the number of capillaries to 0.0020, the coating speed was set to 30 mm / sec and the number of capillaries was set to 0.0040. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1A.

Example 3
In Example 1, instead of setting the coating speed to 15 mm / sec and setting the number of capillaries to 0.0020, the coating speed was set to 50 mm / sec and the number of capillaries was set to 0.0067. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1A.

Example 4
In Example 1, a silver nanowire ink (aqueous coating liquid) 1 was prepared, the aqueous coating liquid viscosity was 6 mPa · s, the aqueous coating liquid surface tension was 45 mN / m, and the capillary number was 0.0020. Instead, the silver nanowire ink (aqueous coating liquid) 2 is prepared with the following composition, the aqueous coating liquid viscosity is 24 mPa · s, the aqueous coating liquid surface tension is 43 mN / m, and the number of capillaries is Except having been set to 0.0084, a silver nanowire transparent conductive film was prepared in the same manner as in Example 1, and the prepared silver nanowire transparent conductive film was subjected to pressure treatment, followed by pressure treatment. The resistance value was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 1A.
<Preparation of silver nanowire ink (aqueous coating liquid) 2>
Silver nanowire ink (aqueous coating liquid) 2 was prepared with the following composition.
(1) Metal nanowire: Silver nanowire (manufactured by Seashell Technology, AgNW-25, average diameter 25 nm, average length 23 μm): compounding amount 0.050 part by mass (2) binder: hydroxypropylmethylcellulose (manufactured by Aldrich, Viscosity of 2% aqueous solution at 20 ° C. 80 cP to 120 cP (document value)): blending amount 0.125 parts by mass (3) Thickener: thickener (Toa Gosei Co., Ltd., A-20L): blending amount 0.075 Parts by mass (4) solvent: (i) water: blending amount 89.750 parts by weight, (ii) ethanol: blending amount 10.000 parts by weight

(Example 5)
In Example 4, instead of setting the coating speed to 15 mm / sec and setting the number of capillaries to 0.0084, the coating speed was set to 30 mm / sec and the number of capillaries was set to 0.0167. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1A.

(Example 6)
In Example 4, instead of setting the coating speed to 15 mm / sec and setting the number of capillaries to 0.0084, the coating speed was set to 50 mm / sec and the number of capillaries was set to 0.0279. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1A.

(Comparative Example 1)
In Example 1, a silver nanowire ink (aqueous coating liquid) 1 was prepared, the aqueous coating liquid viscosity was 6 mPa · s, the aqueous coating liquid surface tension was 45 mN / m, and the capillary number was 0.0020. Instead, the silver nanowire ink (aqueous coating liquid) 3 is prepared with the following composition, the aqueous coating liquid viscosity is 52 mPa · s, the aqueous coating liquid surface tension is 46 mN / m, and the number of capillaries is A silver nanowire transparent conductive film was produced in the same manner as in Example 1 except that the thickness was 0.0170, and the silver nanowire transparent conductive film thus produced was subjected to pressure treatment, followed by pressure treatment. The resistance value was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 1B.
<Preparation of silver nanowire ink (aqueous coating liquid) 3>
Silver nanowire ink (aqueous coating liquid) 3 was prepared with the following composition.
(1) Metal nanowire: Silver nanowire (manufactured by Seashell Technology, AgNW-25, average diameter 25 nm, average length 23 μm): compounding amount 0.050 part by mass (2) binder: hydroxypropylmethylcellulose (manufactured by Aldrich, Viscosity of 2% aqueous solution at 20 ° C. 80 cP to 120 cP (document value)): Blending amount 0.125 parts by mass (3) Thickener: Thickener (A-20L, manufactured by Toagosei Co., Ltd.): Blending amount 0.150 Parts by mass (4) solvent: (i) water: blending amount 89.675 parts by mass, (ii) ethanol: blending amount 10.000 parts by mass

(Comparative Example 2)
In Comparative Example 1, the coating speed was set to 15 mm / sec and the number of capillaries was set to 0.0170, but the coating speed was set to 30 mm / sec and the number of capillaries was set to 0.0339. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1B.

(Comparative Example 3)
In Comparative Example 1, instead of setting the coating speed to 15 mm / sec and setting the number of capillaries to 0.0170, the coating speed was set to 50 mm / sec and the number of capillaries was set to 0.0565. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1B.

(Comparative Example 4)
In Example 1, a silver nanowire ink (aqueous coating liquid) 1 was prepared, the aqueous coating liquid viscosity was 6 mPa · s, the aqueous coating liquid surface tension was 45 mN / m, and the capillary number was 0.0020. Instead, the silver nanowire ink (aqueous coating liquid) 4 is prepared with the following composition, the aqueous coating liquid viscosity is 23 mPa · s, the aqueous coating liquid surface tension is 68 mN / m, and the number of capillaries is Except having been set to 0.0051, a silver nanowire transparent conductive film was prepared in the same manner as in Example 1, and the prepared silver nanowire transparent conductive film was subjected to pressure treatment, followed by pressure treatment of the silver nanowire transparent conductive film. The resistance value was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 1B.
<Preparation of silver nanowire ink (aqueous coating liquid) 4>
Silver nanowire ink (aqueous coating liquid) 4 was prepared with the following composition.
(1) Metal nanowire: Silver nanowire (manufactured by Seashell Technology, AgNW-25, average diameter 25 nm, average length 23 μm): compounding amount 0.050 part by mass (2) binder: hydroxypropylmethylcellulose (manufactured by Aldrich, Viscosity of 2% aqueous solution at 20 ° C. 80 cP to 120 cP (document value)): blending amount 0.125 parts by mass (3) Thickener: thickener (Toa Gosei Co., Ltd., A-20L): blending amount 0.075 Mass part (4) Solvent: Water: Blending amount 99.750 parts by mass

(Comparative Example 5)
In Comparative Example 4, instead of setting the coating speed to 15 mm / sec and setting the number of capillaries to 0.0051, the coating speed was set to 30 mm / sec and the number of capillaries was set to 0.0101. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1B.

(Comparative Example 6)
In Comparative Example 4, the coating speed was set to 15 mm / sec, the number of capillaries was set to 0.0051, and the coating speed was set to 50 mm / sec and the number of capillaries was set to 0.0169. Similarly, a silver nanowire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and coating appearance Was evaluated. The results are shown in Table 1B.

(Comparative Example 7)
In Example 4, instead of setting the coating speed to 15 mm / sec, the surface tension of the aqueous coating liquid to 43 mN / m, and the number of capillaries to 0.0084, the coating speed was set to 200 mm / sec, and the aqueous coating liquid was A silver nanowire transparent conductive film was produced in the same manner as in Example 4 except that the surface tension was 42 mN / m and the number of capillaries was 0.1143, and the produced silver nanowire transparent conductive film was subjected to pressure treatment. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 2.

(Example 7)
In Example 4, instead of setting the surface tension of the aqueous coating solution to 43 mN / m and the number of capillaries to 0.0084, the amount of solvent added is increased, or a surfactant (eg, Triton X manufactured by Sigma-Aldrich) -100), a silver nanowire transparent conductive film was prepared in the same manner as in Example 4 except that the surface tension of the aqueous coating solution was 29 mN / m and the number of capillaries was 0.0124. The produced silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 3.

(Example 8)
In Example 4, instead of setting the surface tension of the aqueous coating solution to 43 mN / m and the number of capillaries to 0.0084, the amount of solvent added is increased, or a surfactant (eg, Triton X manufactured by Sigma-Aldrich) -100), a silver nanowire transparent conductive film was prepared in the same manner as in Example 4 except that the surface tension of the aqueous coating solution was 22 mN / m and the number of capillaries was 0.0164. The produced silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 3.

Example 9
In Example 1, instead of setting the viscosity of the aqueous coating solution to 6 mPa · s, the surface tension of the aqueous coating solution to 45 mN / m, and the number of capillaries to 0.0020, the amount of the binder is increased or the thickener. In the same manner as in Example 1 except that the viscosity of the aqueous coating solution was 37 mPa · s, the surface tension of the aqueous coating solution was 44 mN / m, and the number of capillaries was 0.0126. A wire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. . The results are shown in Table 4.

(Example 10)
In Example 1, instead of setting the viscosity of the aqueous coating solution to 6 mPa · s, the surface tension of the aqueous coating solution to 45 mN / m, and the number of capillaries to 0.0020, the amount of the binder is increased or the thickener. In the same manner as in Example 1, except that the viscosity of the aqueous coating solution was 46 mPa · s, the surface tension of the aqueous coating solution was 43 mN / m, and the number of capillaries was 0.0160. A wire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. . The results are shown in Table 4.

(Comparative Example 8)
In Example 1, instead of setting the viscosity of the aqueous coating solution to 6 mPa · s, the surface tension of the aqueous coating solution to 45 mN / m, and the number of capillaries to 0.0020, the amount of the binder is increased or the thickener. In the same manner as in Example 1, except that the viscosity of the aqueous coating solution is 58 mPa · s, the surface tension of the aqueous coating solution is 43 mN / m, and the number of capillaries is 0.0202. A wire transparent conductive film was prepared, the prepared silver nanowire transparent conductive film was subjected to pressure treatment, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. . The results are shown in Table 4.

(Example 11)
In Example 4, instead of setting the coating gap to 30 μm, the wet coating thickness to 15 μm, and the ratio (coating gap / wet coating thickness) to 2, the coating gap is set to 10 μm and the wet coating thickness is set to A silver nanowire transparent conductive film was prepared in the same manner as in Example 4 except that the thickness was 3 μm and the ratio (coating gap / wet coating thickness) was 3.3. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 5.

Example 12
In Example 4, instead of setting the coating gap to 30 μm, the wet coating thickness to 15 μm, and the ratio (coating gap / wet coating thickness) to 2, the coating gap is set to 15 μm and the wet coating thickness is set to A silver nanowire transparent conductive film was produced in the same manner as in Example 4 except that the ratio (coating gap / wet coating thickness) was 3, and the produced silver nanowire transparent conductive film was pressurized. The resistance value of the processed and pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 5.

(Example 13)
In Example 4, instead of setting the coating gap to 30 μm, the wet coating thickness to 15 μm, and the ratio (coating gap / wet coating thickness) to 2, the coating gap is set to 20 μm and the wet coating thickness is set to A silver nanowire transparent conductive film was prepared in the same manner as in Example 4 except that the ratio (coating gap / wet coating thickness) was 2, and the produced silver nanowire transparent conductive film was pressurized. The resistance value of the processed and pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 5.

(Example 14)
In Example 4, instead of setting the coating gap to 30 μm, the wet coating thickness to 15 μm, and the ratio (coating gap / wet coating thickness) to 2, the coating gap was set to 30 μm and the wet coating thickness was A silver nanowire transparent conductive film was produced in the same manner as in Example 4 except that the ratio (coating gap / wet coating thickness) was 3, and the produced silver nanowire transparent conductive film was pressurized. The resistance value of the processed and pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 5.

(Example 15)
In Example 4, instead of setting the coating gap to 30 μm, the wet coating thickness to 15 μm, and the ratio (coating gap / wet coating thickness) to 2, the coating gap was set to 30 μm and the wet coating thickness was A silver nanowire transparent conductive film was prepared in the same manner as in Example 4 except that the ratio was 20 μm and the ratio (coating gap / wet coating thickness) was 1.5. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 5.

(Example 16)
In Example 4, instead of setting the coating gap to 30 μm, the wet coating thickness to 15 μm, and the ratio (coating gap / wet coating thickness) to 2, the coating gap is set to 45 μm and the wet coating thickness is set to A silver nanowire transparent conductive film was prepared in the same manner as in Example 4 except that the thickness was 10 μm and the ratio (coating gap / wet coating thickness) was 4.5. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 5.

(Example 17)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 40 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 20 μm and the ratio (coating gap / wet coating thickness) was 2. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 6.

(Example 18)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 50 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 20 μm and the ratio (coating gap / wet coating thickness) was 2.5. The film was pressure treated, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 6.

(Example 19)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 70 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 20 μm and the ratio (coating gap / wet coating thickness) was 3.5. The film was pressure treated, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 6.

(Example 20)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 100 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 20 μm and the ratio (coating gap / wet coating thickness) was 5. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 6.

(Example 21)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 120 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 20 μm and the ratio (coating gap / wet coating thickness) was 6. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 6.

(Example 22)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 150 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 20 μm and the ratio (coating gap / wet coating thickness) was 7.5. The film was pressure treated, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 6.

(Example 23)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 180 μm, and wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 20 μm and the ratio (coating gap / wet coating thickness) was 9. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 6.

(Example 24)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 30 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 5 μm and the ratio (coating gap / wet coating thickness) was 6. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 7.

(Example 25)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 30 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 10 μm and the ratio (coating gap / wet coating thickness) was 3. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 7.

(Example 26)
In Example 15, instead of setting the coating gap to 30 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 1.5, the coating gap was set to 30 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 15 except that the thickness was 15 μm and the ratio (coating gap / wet coating thickness) was 2. The resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 7.

(Example 27)
In Example 18, instead of setting the coating gap to 50 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 2.5, the coating gap was set to 50 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 18 except that the thickness was 30 μm and the ratio (coating gap / wet coating thickness) was 1.7. The film was pressure treated, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 8.

(Example 28)
In Example 18, instead of setting the coating gap to 50 μm, the wet coating thickness to 20 μm, and the ratio (coating gap / wet coating thickness) to 2.5, the coating gap was set to 50 μm and the wet coating was performed. A silver nanowire transparent conductive film was prepared in the same manner as in Example 18 except that the thickness was 40 μm and the ratio (coating gap / wet coating thickness) was 1.3. The film was pressure treated, the resistance value of the pressure-treated silver nanowire transparent conductive film was measured, and the resistance distribution and the coating film appearance were evaluated. The results are shown in Table 8.

From Tables 1 to 8, (i) Viscosity of aqueous coating solution: 1 mPa · s to 50 mPa · s, (ii) Surface tension of aqueous coating solution: 20 mN / m to 60 mN / m, (iii) Capillary number Ca: Examples 1 to 28 satisfying all three conditions of 0.03 or less are: (i) Viscosity of aqueous coating solution 1 mPa · s to 50 mPa · s, (ii) Surface tension of aqueous coating solution 20 mN / m Compared with Comparative Examples 1 to 8 that do not satisfy at least one of the three conditions of ˜60 mN / m and (iii) Capillary number Ca of 0.03 or less, the coating resistance is prevented and the sheet resistance value is reduced. It can be seen that a transparent conductive film having a uniform in-plane distribution can be produced.

The transparent conductive film manufactured using the coating method of the present invention is an alternative to a transparent conductive film using metal oxide such as indium tin oxide (ITO) used in electronic devices such as notebook computers and smartphones. It can be suitably used as a product.

DESCRIPTION OF SYMBOLS 1 Flat plate slit die 2 Die head 3 Slit 4 Base material 5 Carrying table 10 Base material 20 Transparent conductive film 30 Pressurized body 40 Press roll (1st roll)
50 Back roll (second roll)
60 Roll vs. X Coating liquid W Slit gap H Coating gap h Wet coating thickness

Claims (7)

A coating liquid preparation step of preparing an aqueous coating liquid containing at least one of metal nanowires and carbon nanotubes, and a solvent containing water as a main solvent;
A coating step of coating the aqueous coating liquid on a substrate using a die coater;
A coating method comprising:
The aqueous coating solution has a viscosity of 1 mPa · s to 50 mPa · s;
The surface tension of the aqueous coating solution is 20 mN / m to 60 mN / m,
A coating method, wherein the capillary number Ca represented by the following formula (1) is 0.03 or less.
(Equation 1)
Ca = μU / σ (1)
(In the above formula (1), μ represents the viscosity (Pa · s) of the aqueous coating solution, U represents the coating speed (m / s) of the aqueous coating solution, and σ represents the aqueous coating solution.) (Represents the surface tension (N / m) of the coating solution.) The coating method according to claim 1, wherein the coating speed of the aqueous coating solution is 100 mm / sec or less. The ratio of the coating gap between the die coater and the substrate to the wet coating thickness of the aqueous coating solution (coating gap / wet coating thickness) is 1.5 to 4.5. Or the coating method of 2. 3. The coating method according to claim 1, wherein the wet coating thickness of the aqueous coating solution is 3 μm to 20 μm. The coating method according to claim 1 or 2, wherein a slit gap of the die coater is 30 to 150 µm. The coating method according to claim 1 or 2, wherein the dry coating thickness of the aqueous coating solution is 30 nm to 70 nm. The coating method according to claim 1 or 2, wherein in the coating step, the coating temperature of the aqueous coating solution is 10 ° C to 60 ° C.

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