JP2011090879A - Method of manufacturing transparent conductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve conductivity of a transparent conductor which is useful as a translucent electromagnetic wave shield film of various display devices, and a transparent electrode and a transparent surface heating element or the like of various electronic devices. <P>SOLUTION: The method of manufacturing the transparent conductor having a conductive layer containing a plurality of metal nano-wires includes a preparation process in which a coating liquid 64 containing a plurality of metal nano-wires is prepared and a coating process in which a metal nano-wire dispersion layer 50 is formed by coating the coating liquid 64 on one main surface of a film 12. The coating process is carried out using a slot die coater 54 having a slot die 52, and when the transfer speed (coating speed) of the film 12 when coating the coating liquid 64 on the one main surface of the film 12 is made v [m/s] and a spacing between a head tip 62 of the slot die 52 and the one main surface of the film 12 is made g[m], the shear rate as shown by v/g [1/s] is 100-10,000 [1/s]. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a transparent conductor, and more particularly to a method for producing a transparent conductor by a high-throughput coating method.

  The transparent conductor has a base having high transmittance and insulation, and a thin film conductive film formed on the base. The transparent conductor is manufactured so as to have surface conductivity while having sufficient light transmittance. Such a transparent conductor having surface conductivity is widely used as a transparent electrode of a flat liquid crystal display, a touch panel, an electroluminescence device and a thin-film solar cell, and as an antistatic layer or an electromagnetic wave shielding layer.

  Patent Document 1 is known as a suitable method for producing this transparent conductor. In the method described in Patent Document 1, a plurality of metal nanowires are placed on a substrate (the metal nanowires are dispersed in a liquid), and the liquid is dried, whereby the metal nanowires are formed on the substrate. A network layer (a layer in which a plurality of metal nanowires are connected in a network) is formed. Moreover, in this patent document 1, a metal nanowire network layer is formed on a base | substrate by throwing several metal nanowires on a base | substrate, disperse | distributing metal nanowire in a liquid, and drying this liquid. The matrix material is put on the metal nanowire network layer, and the matrix material is cured to form a matrix, thereby forming a conductive layer including the matrix and metal nanowires embedded in the matrix. Yes. Patent Document 1 describes that a roll-to-roll process is performed. In this case, the substrate is transported along the transport path by the rotating reel, and the metal nanowire is input along the movement path in the first input part, and the matrix material is input in the second input part. Done along the path.

  According to the method described in Patent Document 1 described above, a transparent conductor having desirable electrical, optical, and mechanical properties can be applied to various substrates, and is manufactured at a low cost with a high throughput process. be able to.

US Patent Application Publication No. 2007/0074316

  The present invention has been made in view of such problems, and is a transparent conductor that can improve the method described in Patent Document 1 and can produce a transparent conductor having improved conductivity. An object is to provide a manufacturing method.

[1] The method for producing a transparent conductor according to the present invention includes a preparation step of preparing a coating liquid containing the plurality of metal nanowires in the method for producing a transparent conductor including a conductive layer containing a plurality of metal nanowires. A coating step of applying the coating liquid onto one main surface of the film, and the coating step is performed using a slot die coater having a slot die, and the coating liquid is applied to the main surface of the film. V / g [1 /] where v is the transport speed (coating speed) of the film and v [m / s], and g [m] is the distance between the head end of the slot die and the one main surface of the film. The shear rate indicated by s] is 100 to 10,000 [1 / s].
[2] In the present invention, the shear rate is 3000 to 7000 [1 / s].
[3] In the present invention, the distance between the head end of the slot die and the one main surface of the film is 50 to 250 μm.
[4] In the present invention, the length of the metal nanowire is 1 to 100 [μm].
[5] In the present invention, the coating solution has a viscosity range of 1 to 100 cP.

  As described above, according to the method for producing a transparent conductor according to the present invention, the transparent conductor useful as a translucent electromagnetic wave shielding film for various display devices, a transparent electrode for various electronic devices, a transparent sheet heating element, and the like. The electrical conductivity of can be further improved.

1A is a cross-sectional view showing an example of a transparent conductor including a conductive layer coated on a substrate, FIG. 1B is a cross-sectional view showing another example of the transparent conductor, and FIG. It is sectional drawing which shows another example. It is explanatory drawing which shows the state of the network of the metal nanowire integrated in the matrix. It is explanatory drawing which shows the state which has apply | coated the coating liquid on the film using the slot die coater. It is a process flow which shows the manufacturing method of the transparent conductor by a roll-to-roll process. 5A to 5C are process diagrams illustrating a method for transferring a conductive layer onto a substrate using a laminated structure including a flexible donor substrate, a release layer, and a conductive layer. 6A to 6C are process diagrams showing a method of transferring a conductive layer onto a substrate using a laminated structure including a flexible donor substrate, a release layer, a conductive layer, an overcoat, and an adhesive layer.

  Hereinafter, an embodiment of a method for producing a transparent conductor according to the present invention will be described with reference to FIGS. 1A to 6C. In the present specification, “to” is used as a meaning including numerical values described before and after the lower limit value and the upper limit value.

  The transparent conductor manufactured by the manufacturing method according to the present embodiment is a transparent conductor including a conductive layer containing metal nanowires. In particular, the conductive layer includes a sparse network of metal nanowires. Furthermore, the conductive layer can be transparent and flexible, can include at least one conductive surface, and can be coated or laminated on the flexible film. The conductive layer can also form part of a composite structure that encloses the matrix material and the nanowires. This matrix material can impart certain chemical, mechanical, and optical properties to the composite structure described above.

[Conductive nanowires]
Metal nanowire 10 (see FIGS. 1A-1C) generally has an aspect ratio (length / diameter) in the range of 10-100,000. In order to obtain a transparent conductive layer, when the aspect ratio is larger, the total density of the metal nanowires 10 can be lowered, the transparency can be increased, and a more efficient conductive network can be formed. It is advantageous. In other words, when using conductive nanowires having a high aspect ratio, the density of the metal nanowires 10 realizing the conductive network can be sufficiently low to such an extent that the conductive network is substantially transparent. Become. The silver nanowire layer on the PET (polyethylene terephthalate) film is substantially transparent at about 440 nm to 700 nm.

  Conductive nanowires include metal nanowires and other conductive particles having a high aspect ratio (eg, higher than 10). Examples of non-metallic nanowires include, but are not limited to, carbon nanotubes (CNTs), metal oxide nanowires, conductive polymer fibers, and the like.

  “Metal nanowire” refers to a metal wire containing an elemental metal, a metal alloy, or a metal compound (including a metal oxide). At least one cross-sectional dimension of the metal nanowire is less than 500 nm, preferably less than 200 nm, or more preferably less than 100 nm. As described above, the aspect ratio (length: width) of the metal nanowire is greater than 10, preferably greater than 50, or more preferably greater than 100. Suitable metal nanowires can be composed of any metal, including but not limited to silver, gold, copper, nickel, and gold-plated silver.

  Metal nanowires can be prepared by known methods. In particular, silver nanowires can be synthesized through solution phase reduction of a silver salt (eg, silver nitrate) in the presence of a polyol (eg, ethylene glycol) and poly (vinyl pyrrolidone). For example, Xia, Y. et al. Et al., Chem. Mater. (2002), 14, 4736-4745, and Xia, Y. et al. Et al., Nanoletters (2003) 3 (7), 955-960.

[Conductive layer and film]
As a specific example, FIG. 1A shows a transparent conductor 16 including a conductive layer 14 coated on a film 12. The conductive layer 14 includes a plurality of metal nanowires 10. The metal nanowire 10 forms a conductive network.

FIG. 1B shows another example of the transparent conductor 16. The conductive layer 14 is the same as the example of FIG. 1A in that the conductive layer 14 is formed on the film 12, but the conductive layer 14 includes a plurality of metal nanowires 10 incorporated in the matrix 18.
FIG. 1C shows still another example of the transparent conductor 16. The conductive layer 14 is the same as the example of FIG. 1A in that the conductive layer 14 is formed on the film 12, but the conductive layer 14 is formed by the metal nanowire 10 incorporated in a part of the matrix 18, and is completely formed in the matrix 18. It differs in that it is immersed.

  The “matrix” refers to a solid substance in which the metal nanowires 10 are dispersed or incorporated. A portion of the metal nanowire 10 may protrude from the matrix material to allow access to the conductive network. The matrix 18 is a host for the metal nanowire 10 and provides the physical shape of the conductive layer 14. The matrix 18 protects the metal nanowire 10 from adverse environmental factors such as corrosion and wear. In particular, the matrix 18 prevents the penetration of corrosive elements such as environmental moisture, trace amounts of acid, oxygen, sulfur and the like.

  In addition, the matrix 18 imparts favorable physical and mechanical properties to the conductive layer 14. For example, the adhesive force with respect to the film 12 can be provided. Furthermore, unlike metal oxide films, polymer or organic matrices incorporating metal nanowires 10 can be rigid and flexible. Note that the flexible matrix enables the production of the transparent conductor 16 by a low-cost and high-speed mass processing process.

  Furthermore, the optical characteristics of the conductive layer 14 can be adjusted by selecting an appropriate matrix material. For example, reflection loss and unwanted glare can be effectively reduced by using a matrix 18 having the desired refractive index, composition and thickness.

  In general, the matrix 18 is an optically transparent material. A substance is considered optically transparent when the light transmittance of the substance in the visible region (400 nm to 700 nm) is at least 80%.

  The matrix 18 is about 10 nm to 5 μm thick, about 20 nm to 1 μm thick, or about 50 nm to 200 nm thick, and has a refraction of about 1.3 to 2.5, or about 1.35 to 1.8. Have a rate.

  The matrix 18 may be, for example, a polymer (also referred to as a polymer matrix). Optically transparent polymers are known in the art. Examples of suitable polymer matrices include polymethacrylates (eg, poly (methyl methacrylate)), polyacrylates such as polyacrylates and polyacrylonitrile, polyvinyl alcohol, polyesters (eg, polyethylene terephthalate (PET), polyester naphthalate, And polycarbonate), phenol or cresol-formaldehyde (Novolacs®), polystyrene, polyvinyltoluene, polyvinylxylene, polyimide, polyamide, polyamideimide, polyetheramide, polysulfide, polysulfone, polyphenylene, and polyphenylether. Aromatic polymers, polyurethane (PU), epoxy, polyolefin (eg polypropylene, Limethylpentene, and cyclic olefins), acrylonitrile-butadiene-styrene copolymers (ABS), cellulose derivatives, silicones and other silicon-containing polymers (eg, polysilsesquioxanes and polysilanes), polyvinyl chloride (PVC), polyacetates, Polynorbornene, synthetic rubbers (eg EPR, SBR, EPDM) and fluoropolymers (eg polyvinylidene fluoride, polytetrafluoroethylene (TFE) or polyhexafluoropropylene), copolymers of fluoro-olefins and hydrocarbon olefins (eg , Lumiflon®), and amorphous fluorocarbon polymers or copolymers (eg, CYTOP® from Asahi Glass Co., or Teflon AF from DuPont) They include, but are not limited to.

  The matrix 18 itself may be conductive. For example, the matrix 18 may be a conductive polymer. Conductive polymers are well known in the art and include, but are not limited to, poly (3,4-ethylenedioxythiophene) (PEDOT), polyaniline, polythiophene, and polydiacetylene.

  The “conductive layer” or “conductive film” refers to the network layer of the metal nanowire 10 that provides the conductive medium of the transparent conductor 16. When the matrix 18 is present, the combination of the metal nanowire 10 network layer and the matrix 18 is also referred to as a “conductive layer”. The surface conductivity of the conductive layer 14 is inversely proportional to its surface resistance, sometimes referred to as sheet resistance, and can be measured by methods known in the art.

The matrix 18 must be filled with sufficient metal nanowires 10 to be conductive. The “reference content” means that the conductive layer 14 is about 10 ⁶ ohm / sq. The weight percentage of the metal nanowire 10 contained in the conductive layer 14 when the surface resistivity is (or ohm / □) or less. The reference content depends on the aspect ratio, the degree of alignment, the degree of aggregation, the resistivity, and the like of the metal nanowire 10.

The mechanical and optical properties of the matrix 18 are susceptible to change or damage due to the introduction of any particles in the matrix 18. Advantageously, if the high aspect ratio of the metal nanowire 10 is high, the reference content is preferably about 0.05 μg / cm ² to about 10 μg / cm ² , more preferably about 0.00, in the case of silver nanowires. 1 [mu] g / cm ² ~ about 5 [mu] g / cm ^2, as more preferably about 0.8 [mu] g / cm ² ~ about 3 [mu] g / cm ^2, arrangement of the conductive network through the matrix 18 becomes possible. These inputs do not affect the mechanical or optical properties of the matrix 18. These values strongly depend on the size and spatial dispersion of the metal nanowire 10. As an advantage, by adjusting the content of the metal nanowire 10, it is possible to provide the transparent conductor 16 whose electric conductivity (or surface resistivity) and light transmittance can be adjusted.

  As shown in FIG. 1B, the conductive layer 14 extends throughout the thickness of the matrix 18. Advantageously, certain portions of the metal nanowire 10 are exposed on the matrix surface 20 due to the surface tension of the matrix material (eg, polymer). This feature is particularly useful for touch screen applications. The transparent conductor 16 exhibits surface conductivity on at least one surface thereof.

  FIG. 2 illustrates how the network of metal nanowires 10 incorporated in the matrix 18 is believed to obtain surface conductivity. As shown, the metal nanowire 10 may be “immersed” in the matrix 18, while the end 10 a of the metal nanowire 10 protrudes onto the surface 20 of the matrix 18. Further, a part of the central portion 10 b of the metal nanowire 10 may protrude on the surface 20 of the matrix 18. When a sufficient number of end portions 10a and central portions 10b of the metal nanowires protrude on the matrix 18, the surface of the transparent conductor 16 has conductivity.

  “Film” or “selected film” refers to the material on which conductive layer 14 is coated or laminated. The film 12 may be transparent or opaque. The “selected film” is used in relation to the laminating process, as will be described later. Suitable high stiffness films 12 include polyesters (eg, polyethylene terephthalate (PET), polyester naphthalate, and polycarbonate), polyolefins (eg, linear, branched, and cyclic polyolefins), polyvinyls (eg, chloride). Polyvinyl, polyvinylidene chloride, polyvinyl acetal, polystyrene, polyacrylate, etc.), cellulose ester-based (eg, cellulose triacetate, cellulose acetate), polysulfones such as polyethersulfone, polyimide, silicone, and other conventional polymer films. However, it is not limited to these.

[Performance enhancement layer]
As described above, the conductive layer 14 has excellent physical and mechanical characteristics due to the matrix 18. These features can be further enhanced by introducing additional layers into the transparent conductor 16. Additional layers include one or more layers such as, for example, an antireflection layer, an antiglare layer, an adhesive layer, a barrier layer, and a hard coat.

[Corrosion inhibitor]
The transparent conductor 16 may include a corrosion inhibitor in addition to or in place of the barrier layer described above. Various corrosion inhibitors protect the metal nanowire 10 based on various mechanisms.

  The corrosion inhibitor easily binds to the metal nanowire 10 and forms a protective film on the metal surface. These are also referred to as barrier forming corrosion inhibitors.

[Deposition of nanowires and production of transparent conductors]
In the method of manufacturing the transparent conductor 16, a plurality of metal nanowires 10 are deposited on the surface of the film 12 (the metal nanowires 10 are dispersed in the liquid), and the liquid is dried. Forming a metal nanowire network layer on 12.

  The metal nanowire 10 can be prepared as described above. In general, the metal nanowires 10 are dispersed in a liquid to facilitate deposition. “Deposition” and “coating” are used interchangeably. Any non-corrosive liquid capable of forming a coating liquid in which the metal nanowires 10 are uniformly dispersed (also referred to as “metal nanowire dispersion” or “coating liquid”) can be used. Preferably, the metal nanowire 10 is dispersed in water, alcohol, ketone, ether, hydrocarbon, or aromatic solvent (benzene, toluene, xylene, etc.). More preferably, the liquid is volatile and has a boiling point of 200 ° C. or lower, or 150 ° C. or lower, or 100 ° C. or lower.

  In addition, the coating liquid in which the metal nanowires 10 are dispersed may contain an additive and a binder in order to adjust viscosity, corrosion, adhesion, and nanowire dispersion. Examples of suitable additives and binders include carboxymethylcellulose (CMC), 2-hydroxyethylcellulose (HEC), hydroxypropylmethylcellulose (HPMC), methylcellulose (MC), polyvinyl alcohol (PVA), tripropylene glycol (TPG) , And xanthan gum (XG) and surfactants such as ethoxylates, alkoxylates, ethylene oxide and propylene oxide and copolymers thereof, sulfonates, sulfates, disulfonates, sulfosuccinates, phosphate esters, and fluoro Surfactants (such as, but not limited to, Zonyl®, DuPont).

  In one example, the coating solution is 0.0025 wt% to 0.1 wt% surfactant (for example, for Zonyl® FSO-100, the preferred range is 0.0025 wt% to 0.05 wt%). 0.02 wt% to 4 wt% viscosity modifier (e.g., for HPMC, the preferred range is 0.02 wt% to 0.5 wt%), 94.5 wt% to 99.0 wt% solvent, And 0.05 wt% to 1.4 wt% of metal nanowires. Representative examples of suitable surfactants include Zonyl (R) FSN, Zonyl (R) FSO, Zonyl (R) FSH, Triton (x100, x114, x45), Dynol (604, 607). , N-dodecyl bD-maltoside and Novek®. Examples of suitable viscosity modifiers include hydroxypropyl methylcellulose (HPMC), methylcellulose, xanthan gum, polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose. Examples of suitable solvents include water and isopropanol.

  If it is desired to change the concentration of the coating solution from the above, it is possible to increase or decrease the solvent percentage. However, in a preferred embodiment, the relative proportions of the other components can remain the same. In particular, the ratio of the surfactant to the viscosity modifier is preferably in the range of 80 to 0.01, and the ratio of the viscosity modifier to the metal nanowire 10 is preferably in the range of 5 to 0.000625. The ratio of the metal nanowire 10 to the activator is preferably in the range of 560-5. The ratio of the components of the coating solution may be modified as appropriate according to the film and the coating method used. A preferable viscosity range of the coating solution is 1 to 100 cP.

  As an optional treatment, the film 12 can be pretreated (surface pretreatment) to prepare the surface for better subsequent deposition of the metal nanowires 10. This surface pretreatment has multiple functions. For example, a uniform metal nanowire dispersion layer 50 can be deposited. In addition, the metal nanowires 10 can be fixed on the film 12 for later process steps. Furthermore, in order to pattern and deposit the metal nanowire 10, a pretreatment can be performed in conjunction with the patterning step. Pretreatment may include solvent or chemical cleaning, heating, deposition of an arbitrarily patterned intermediate layer to provide the appropriate chemical or ionic state to the coating solution, plus plasma treatment, UV-ozone treatment, or Further surface treatments such as corona discharge can be mentioned.

  After deposition, the liquid is removed by evaporation. Evaporation can be accelerated by heating (eg, calcination). Post-treatment may be performed to impart conductivity to the resulting metal nanowire network layer. As described below, this post-treatment may be a process step that includes heat, plasma, corona discharge, UV-ozone, or pressure treatment.

  In the present embodiment, the transparent conductor 16 is manufactured by applying a coating solution containing a plurality of metal nanowires dispersed in a liquid on the surface of the film 12 and dispersing the metal nanowires on the film 12. By forming a layer 50 (see FIG. 3) and drying the liquid in the metal nanowire dispersion layer 50, a metal nanowire network layer is formed on the film 12, and a matrix material is formed on the metal nanowire network layer. Covering and curing the matrix material to form the matrix 18.

  “Matrix material” refers to a material or mixture of materials that can be cured into a matrix. “Curing” or “curing” refers to the process by which monomers or partial polymers (less than 150 monomers) are polymerized and / or crosslinked to form a solid polymer matrix. Suitable polymerization conditions are well known in the art, and examples include heating of the monomer, irradiation of the monomer with visible or ultraviolet light (UV), electron beam, and the like. In addition, the “solidification” of the polymer / solvent system that occurs simultaneously with solvent removal is also within the scope of “curing”.

  The matrix material includes a polymer, and the same materials as described above can be used. The matrix material includes a prepolymer. “Prepolymer” refers to a mixture of monomers, a mixture of oligomers, or a mixture of partial polymers that can be polymerized and / or crosslinked to form a polymer matrix. It is within the knowledge of the person skilled in the art to select the appropriate monomer or partial polymer in view of the desired polymer matrix.

  In a preferred embodiment, the prepolymer is photocurable. That is, the prepolymer is polymerized and / or crosslinked by irradiation. As described in more detail, the matrix 18 based on the photocurable prepolymer can be patterned by irradiation in selected areas. The prepolymer may be thermosetting and can be patterned by selectively applying heat from a heat source.

  In general, the matrix material is a liquid. The matrix material may optionally contain a solvent. Any non-corrosive solvent that can effectively solvate or disperse the matrix material can be used. Examples of suitable solvents include water, alcohols, ketones, tetrahydrofuran, hydrocarbons (eg, cyclohexane) or aromatic solvents (benzene, toluene, xylene, etc.). More preferably, the solvent is volatile and has a boiling point of 200 ° C. or lower, or 150 ° C. or lower, or 100 ° C. or lower.

  The matrix material may contain a crosslinking agent, a polymerization initiator, a stabilizer (for example, an antioxidant and a UV stabilizer that extend the product lifetime, and a polymerization inhibitor that extends the shelf life), a surfactant, and the like. Good. The matrix material may further include a corrosion inhibitor.

  Then, as shown in FIG. 3, the coating liquid 64 described above is applied onto the film 12 using a slot die coater 54 having a slot die 52. The film 12 travels along a predetermined transport path by the transport roller 56.

  The slot die 52 is provided with a manifold 58 and a slit 60 connected thereto. In addition, the slot die 52 is installed so that its front end (nozzle portion of the slit 60: referred to as a head front end 62) and the transport roller 56 face each other. Accordingly, the head tip 62 of the slot die 52 is opposed to the film 12 traveling by the transport roller 56.

  The coating liquid 64 supplied to the slot die 52 is diffused by the manifold 58 in the width direction of the slot die 52 (the same direction as the width direction of the film 12), and then from the head end 62 of the slot die 52 via the slit 60. The ink is discharged toward the film 12 (the running film 12).

  The coating liquid 64 discharged from the head tip 62 of the slot die 52 continuously forms the metal nanowire dispersion layer 50 on the film 12 while forming a bead 66 with the film 12.

  In this embodiment, the transport speed (coating speed) of the film 12 when the coating liquid 64 is applied to one main surface of the film 12 (the surface facing the head tip 62) is v [m / s], the slot. When the distance between the head tip 62 of the die 52 and one main surface of the film 12 is g [m], the shear rate indicated by v / g [1 / s] is 100 to 10,000 [1 / s]. I have to. Thereby, the dispersibility of the metal nanowire 10 in the metal nanowire dispersion layer 50 apply | coated on the film 12 will improve.

  Here, the improvement of dispersibility means that the orientation of the metal nanowires 10 is not dispersed without the orientation of the plurality of metal nanowires 10 being aligned in one direction. When the dispersibility of the metal nanowire 10 is improved, when the transparent conductor 16 is formed thereafter, the surface resistance of the transparent conductor 16 is almost free from anisotropy and ideally isotropic. That is, conductivity is improved in all directions.

  By the way, when the method of continuously forming the metal nanowire dispersion layer 50 on the film 12 as described above is adopted, depending on the aspect ratio of the metal nanowire 10, the major axis of most of the metal nanowires 10 is the film. There is a possibility that it will be almost aligned in the 12 transport direction (MD direction). However, by specifying the shear rate as described above, for example, the ratio of the metal nanowire 10 whose major axis is along the MD direction and the metal nanowire 10 along the TD direction (direction orthogonal to the transport direction) becomes substantially the same. The dispersibility of the metal nanowire 10 is improved. Of course, there are metal nanowires 10 whose major axis extends in a direction other than the MD direction or the TD direction, but when viewed as a whole, the orientation state of each metal nanowire 10 is varied.

  The distance g between the head tip 62 of the slot die 52 and one main surface of the film 12 is preferably 50 to 250 μm. If the gap g is too small, the nozzle (head tip 62) may be blocked by the bead 66, or uneven coating of the metal nanowire dispersion layer 50 may occur. On the other hand, if the gap g is too large, it becomes difficult to cause the coating liquid 64 to reach the film 12 even with the spray force of the slot die 52, and there is a possibility that uneven coating of the metal nanowire dispersion layer 50 may occur.

<Method for producing transparent conductor: Overview>
Here, an outline of a method for producing a transparent conductor according to the present embodiment will be described. First, as described above, the coating liquid 64 is applied onto the film 12 using the slot die coater 54 to form the metal nanowire dispersion layer 50 on the film (see FIG. 3). The film 12 may be pretreated to allow deposition of the metal nanowire dispersion layer 50 applied to the film 12 for later process steps. This process includes solvent cleaning or chemical cleaning, heating, deposition of an arbitrarily patterned intermediate layer to provide the appropriate chemical or ionic state to the metal nanowire dispersion layer 50, plus plasma processing, UV- Mention may be made of further surface treatments such as ozone treatment or corona discharge.

  For example, the intermediate layer can be deposited on the surface of the film 12 to fix the metal nanowires 10. The intermediate layer functionalizes and modifies its surface and facilitates the bonding of the metal nanowires 10 to the film 12. Prior to the deposition of the metal nanowire 10, an intermediate layer may be coated on the film 12. An intermediate layer may be deposited with the metal nanowires 10.

  Thereafter, the metal nanowire dispersion layer 50 on the film 12 is dried to evaporate the liquid in the metal nanowire dispersion layer 50. As a result, the metal nanowire network layer 114 is formed on the film 12.

  The formed metal nanowire network layer 114 may require further post-treatment to impart electrical conductivity. As described in more detail below, this post-treatment may be a process step that includes heat, plasma, corona discharge, UV-ozone, or pressure treatment.

  Thereafter, a matrix material is coated on the metal nanowire network layer 114 using, for example, a roller, and a layer made of the matrix material (matrix material layer 116: see FIG. 4) is formed. Then, the matrix material layer 116 is cured to obtain the matrix 18, whereby the transparent conductor 16 having the structure of FIGS. 1A to 1C and FIG. 2 is obtained.

  It should be noted that a brush, stamp, spray applicator, slot die coater, or any other suitable applicator can be used in the matrix material application instead of rollers.

<Method for producing transparent conductor: roll-to-roll process>
Next, an embodiment in which the manufacturing process described above is applied to a roll-to-roll process will be described with reference to FIG.

  The web coating system 146 shown in FIG. 4 includes a take-up roll 147 that is driven by a motor (not shown). The take-up roll 147 pulls out the film 12 from the supply roll 148 along the movement path 150. Thereafter, the film 12 is continuously processed and coated along the movement path 150.

  In the present embodiment, a pretreatment is further performed for the purpose of preparing a substrate for a subsequent coating process. More specifically, the film 12 can be optionally subjected to surface treatment at the pretreatment station 160 in order to improve the efficiency of subsequent nanowire deposition. In addition, the surface treatment of the film prior to deposition can improve the uniformity of the metal nanowires 10 that are subsequently deposited.

The surface treatment can be performed by a method known in the art. For example, plasma surface treatment can be used to change the molecular structure of the surface of the film 12. Plasma surface treatment can use gases such as argon, oxygen, or nitrogen to create species that are more reactive at low temperatures. In general, since only a few atomic layers on the surface are involved in the process, the bulk properties of film 12 (eg, polymer film) remain unchanged by chemical reaction. In many cases, plasma surface treatment provides adequate surface activity that improves wettability and adhesive bonding. As a specific example, an oxygen plasma treatment can be performed with the March PX250 system using the following operating parameters. The parameters are 150 W, 30 seconds, the O ₂ flow rate is 62.5 sccm, and the pressure is about 400 mTorr.

  The surface treatment may include depositing an intermediate layer on the film 12. As described above, the intermediate layer generally has an affinity for both the metal nanowire 10 and the film 12. Therefore, the intermediate layer enables the metal nanowire 10 to be fixed and the metal nanowire 10 to be attached to the film 12. Exemplary materials suitable as the intermediate layer include multifunctional biomolecules including polypeptides (eg, poly-L-lysine).

  Other typical surface treatments include surface cleaning with solvents, corona discharge, and UV / ozone treatment, all known to those skilled in the art.

  The film 12 then goes to the metal nanowire deposition station 164 that supplies the metal nanowire dispersion layer 50. In the deposition station 164, a slot die coater 54 having a slot die 52 as shown in FIG. Accordingly, the metal nanowire dispersion layer 50 is deposited on the surface of the film 12 at the deposition station 164.

  The metal nanowire dispersion layer 50 can optionally be rinsed at the rinse station 172. Thereafter, the metal nanowire dispersion layer 50 is dried at the drying station 176, thereby forming the metal nanowire network layer 114 on the film 12.

The metal nanowire network layer 114 can optionally be processed at a post-processing station 184. For example, surface treatment of the metal nanowire 10 with argon or oxygen plasma can improve the permeability and conductivity of the metal nanowire network layer 114. As a specific example, Ar or N ₂ plasma can be performed by a March PX250 system using the following operating parameters. The parameters are 300 W, 90 seconds (or 45 seconds), Ar or N ₂ gas flow rate of 12 sccm, and pressure of about 300 mTorr. Similarly, other known surface treatments (eg corona discharge or UV / ozone treatment) may be used. For example, the Enercon system can be used for corona treatment.

  As part of the post-processing, the metal nanowire network layer 114 can be further pressurized. More specifically, metal nanowire network layer 114 is fed through rollers 186 and 187, and these rollers apply pressure to surface 185 of metal nanowire network layer 114. Similarly, a single roller can be used.

  As an advantage, when the metal nanowire network layer 114, particularly the metal nanowire network layer 114 is subjected to pressure treatment prior to the application of the matrix material, the conductivity of the conductive layer 14 can be improved. In the following description, a transparent conductive material such as a work with the metal nanowire network layer 114 formed on the film 12 or a work with the matrix 18 formed on the metal nanowire network layer 114 is finally obtained. The workpiece in the stage before becoming the body 16 is referred to as a transparent conductor precursor.

  In particular, one or more rollers (e.g., cylindrical rods) may be used to apply pressure to one or both sides of the sheet-like transparent conductor precursor, the one or both sides being Although not necessary, the length dimension may be larger than the width dimension of the conductive layer. If a single roller is used, the metal nanowire network layer may be placed on a hard surface, and a single method can be used using known methods while pressure is applied to the roller. The roller rotates the exposed surface of the conductive layer. If two rollers are used, the metal nanowire network layer 114 may be rolled between the two rollers, as shown in FIG.

  Also, a pressure of 50 to 10,000 psi may be applied to the transparent conductor precursor by one or more rollers. Also, 100-1000 psi, or 200-800 psi, or 300-500 psi may be added. Preferably, pressure is applied to the transparent conductor precursor prior to application of any matrix material.

  If more than one roller is used to apply pressure to the metal nanowire network layer 114, a “nip” or “pinch” roller may be used. Nip or pinch rollers are well understood in the art and are described, for example, in the 3M Technical Report “Lamination Techniques for Converters of Laminating Adhesives” (March 2004). Has been.

  Either before or after application of the plasma treatment described above, pressurization of the metal nanowire network layer 114 improves its electrical conductivity, and this pressurization is performed with or without prior or subsequent plasma treatment. It was found that it could be done. As shown in FIG. 4, the rollers 186 and 187 may rotate the surface 185 of the metal nanowire network layer 114 one or more times. If the roller rotates multiple times on the metal nanowire network layer 114, the rotation may be in the same direction (eg, along the travel path 150) or different relative to an axis parallel to the surface of the sheet being rolled It may be performed in a direction (not shown).

  For example, the conductive network 810 with metal nanowires 10 after pressurization at about 1000 psi to about 2000 psi using a stainless steel roller includes a plurality of nanowire intersections. At least the top nanowires at each intersection have a flat cross section where the intersecting portions are pressed together by pressure, thereby adding to the conductivity of the conductive network by the metal nanowires 10 The connectivity has been enhanced.

  Moreover, you may heat as a post-process. Generally, the transparent conductor precursor is heated to any one of 80 ° C. to 250 ° C. for 10 minutes or less, more preferably 100 ° C. to 160 ° C. for any one of 10 seconds to 2 minutes. The

  Heating can be done either online or offline. For example, in an off-line process, the transparent conductor precursor can be placed in an oven (referred to as a sheet oven) that can dry a sheet-like product set at a predetermined temperature for a predetermined time. Heating the transparent conductor precursor by such a method is advantageous in improving the conductivity of the transparent conductor 16. For example, the transparent conductor 16 manufactured using a roll-to-roll process as shown in FIG. 4 is placed in the above-described sheet oven set at a temperature of 200 ° C. for 30 seconds in this embodiment. It was. The transparent conductor 16 has a surface resistivity of about 12 kOhm / sq. About 58 ohm / sq. After post-treatment. Declined.

  In another example, a similarly prepared second transparent conductor was heated in a sheet oven at 100 ° C. for 30 seconds. The resistivity of the second transparent conductor is about 19 k ohm / sq. To about 400 ohm / sq. Declined. It is also considered that the transparent conductor 16 may be heated using a method other than the sheet oven. For example, an infrared lamp can be used to heat the transparent conductor 16, either in-line or off-line. RF current can also be used to heat the metal nanowire network layer 114 of the metal nanowire 10. The RF current may be induced in the metal nanowire network layer 114 by either broadcast microwaves or currents induced through electrical contacts to the metal nanowire network layer 114.

  Furthermore, a post-treatment that applies both heat and pressure to the transparent conductor 16 can be used. In particular, to apply pressure, the transparent conductor 16 can be installed via one or more rollers as described above. The roller may be heated to apply heat simultaneously. The pressure applied by the roller is preferably 10 to 500 psi, more preferably 40 to 200 psi. The roller is preferably heated to 70 ° C to 200 ° C, more preferably 100 ° C to 175 ° C. Such a combination of heating and pressurization can improve the conductivity of the transparent conductor 16. A machine that can be used to apply both the appropriate pressure and heat simultaneously is Banner American Products of Temecula, Calif. Laminator by. The combination of heating and pressing can be done either before or after deposition and curing of the matrix or other layer as described below.

  Other post-processing techniques used to improve the conductivity of the transparent conductor 16 are the metal wire conductive network of the transparent conductor 16 manufactured as disclosed herein as a metal reducing agent. It is to expose. In particular, the silver nanowire conductive network can be exposed to a silver reducing agent, preferably sodium borohydride, preferably for any of 10 seconds to 30 minutes, more preferably for 1 minute to 10 minutes. As those skilled in the art will appreciate, such processing can be performed either inline or offline.

As described above, such treatment can improve the conductivity of the transparent conductor 16. For example, a silver nanowire transparent conductor 16 on a PET film prepared according to the roll-to-roll process shown in FIG. 4 is exposed to 2% NaBH ₄ for 1 minute, then rinsed with water and dried in air. It was done. The transparent conductor 16 is about 134 ohm / sq. Of about 9 ohm / sq. After this post-treatment. Resistivity.

  The film 12 is then directed to a matrix deposition station 188 that supplies the matrix material 190. The matrix deposition station 188 may be a spraying device, a brushing device, a printing device or the like in addition to a storage tank. Thus, the matrix material layer 116 is deposited on the metal nanowire network layer 114. Advantageously, the matrix material 190 can be deposited by a printing device and formed as a patterned matrix material layer 116.

  Thereafter, the matrix material layer 116 is cured at the curing station 200. If the matrix material is a polymer / solvent system, the matrix material layer 116 can be cured by evaporating the solvent. The curing process can be accelerated by heating (for example, firing). When the matrix material 190 includes a radiation curable prepolymer, the matrix material layer 116 can be cured by irradiation. Depending on the type of prepolymer, thermosetting (thermal induction polymerization) can also be used.

  Optionally, a patterning step can be performed before the matrix material layer 116 is cured. Patterning station 198 can be positioned after matrix deposition station 188 and before curing station 200.

  The curing step forms the conductive layer 14 including the metal nanowire network layer 114 in the matrix 18. Conductive layer 14 can be further processed at post-processing station 214.

  The conductive layer 14 can be surface treated at a post-processing station 214 to expose a portion of the metal nanowire 10 on the surface of the conductive layer 14. For example, a very small amount of matrix can be removed by etching by solvent, plasma treatment, corona discharge, or UV / ozone treatment. Exposed metal nanowires are particularly useful for touch screen applications.

  Some metal nanowires 10 are exposed on the surface of the conductive layer 14 after the curing process (see FIG. 2), and no etching step is required. In particular, if the thickness of the matrix material layer 116 and the surface tension of the matrix material 190 are appropriately adjusted, the matrix 18 does not wet the upper metal nanowire network, and a part of the metal nanowire 10 is formed on the conductive layer 14. It will be exposed on the surface.

  Thereafter, the conductive layer 14 and the film 12 are drawn out by a take-up roll 147. This manufacturing flow process is also referred to as a “reel-to-reel” or “roll-to-roll” process. The film 12 can be stabilized by optionally moving along the conveyor belt.

  In the “roll-to-roll” process, multiple coating steps can be performed along the moving path of the moving film 12. Accordingly, the web coating system 146 can be customized or modified to incorporate any number of additional coating stations as needed. For example, the coating of a performance enhancing layer (antireflection, adhesion, barrier, antiglare, protective layer or film) can be fully integrated into the flow process.

  Advantageously, the roll-to-roll process can produce a uniform transparent conductor at high speed and low cost. In particular, due to the continuous flow of the coating process, the coating layer has no trailing edges.

<Modified example of manufacturing method of transparent conductor>
Despite its versatility, the “roll-to-roll” process is incompatible with high-rigidity substrates such as glass. Highly rigid substrates can be coated by sheet coating, and in some cases can be done on a conveyor belt, but generally corner and / or lack of uniformity occurs. In addition, sheet coating is a lower throughput process and can significantly increase manufacturing costs.

Thus, here, a lamination process for manufacturing a transparent conductor 16 using a flexible donor film is described. This process is compatible with both highly rigid and flexible substrates. More specifically, the lamination process includes the following processes.
(I) Step of coating the conductive layer 14 on the flexible donor film (the conductive layer 14 includes a plurality of metal nanowires 10 that may be embedded in the matrix 18)
(Ii) Step of separating the conductive layer 14 from the flexible donor film (iii) Step of transferring the conductive layer 14 to the selected substrate

  Advantageously, since the donor film is flexible, the coating step on the flexible donor film can be performed by a roll-to-roll process. The conductive layer 14 thus formed can then be transferred to a selected substrate (which can be highly rigid or flexible) through standard lamination processes. If only the metal nanowires 10 are deposited on a flexible donor film and no matrix material is used, a laminating adhesive may be used to adhere the conductive layer 14 to the selected substrate. .

  “Flexible donor film” refers to a flexible film having the form of a sheet, film, web, or the like. The flexible donor film is not particularly limited as long as it can be separated from the conductive layer 14. The flexible donor film may be any flexible film 12. In addition, the flexible donor film may be a woven or non-woven fabric, paper or the like. The flexible donor film need not be optically transparent.

  The flexible donor film can be pre-coated with a release layer before the conductive layer 14 is coated. The “peeling layer” refers to a thin layer that is adhered to the donor film and on which the conductive layer 14 can be formed by web coating. The release layer should be able to easily remove the donor film from the conductive layer 14 without damaging the conductive layer 14. Generally, the release layer is formed from a material having a low surface energy, including but not limited to silicone-based polymers, fluorinated polymers, starches, and the like.

  FIG. 5A shows an example of a laminated structure 230 that includes a flexible donor film 240, a release layer 244 coated on the flexible donor film 240, and a conductive layer 14 coated on the release layer 244. ing.

  The laminated structure 230 can be manufactured using the flexible donor film 240 in the same manner as described with respect to FIG. Prior to the deposition of the metal nanowire 10, a release layer 244 is deposited or coated on the flexible donor film 240. The conductive layer 14 can be formed by depositing the matrix 18 after the metal nanowire 10 is deposited.

  Thereafter, the conductive layer 14 is uniformly transferred to the selected substrate 260. In particular, the high-rigidity substrate 260 (for example, glass) is generally not suitable for a roll-to-roll coating process, but the conductive layer 14 can be laminated. As shown in FIG. 5B, the laminated structure 230 is transferred to the substrate 260 by bringing the surface 262 of the conductive layer 14 into contact with the substrate 260 (eg, glass). The polymer matrix (eg, PET, PU, polyacrylate) adheres appropriately to the substrate 260. Thereafter, as shown in FIG. 5C, the flexible donor film 240 can be removed by separating the release layer 244 from the conductive layer 14.

  The adhesive layer can be used to better bond the conductive layer 14 and the substrate 260 during the lamination stage. FIG. 6A shows a laminated structure 270 that includes a release layer 244 and a conductive layer 14, an overcoat 274 and an adhesive layer 278 in addition to the flexible donor film 240. The adhesive layer 278 has an adhesive surface 280.

  Laminate structure 270 can be manufactured by the roll-to-roll process described in connection with FIG. 4, and web coating system 146 provides an additional station for coating the adhesive layer and overcoat. Will be understood. The adhesive layer is defined herein (eg, polyacrylate, polysiloxane) and can be pressure sensitive, heat soluble, radiation curable, and / or thermosetting. The overcoat can be one or more performance enhancing layers including a hardcoat, an antireflective layer, a protective film, a barrier layer, and the like.

  In FIG. 6B, the laminated structure 270 is bonded to the substrate 260 via the adhesive surface 280. Thereafter, as shown in FIG. 6C, the flexible donor film 240 is removed by separating the release layer 244 from the overcoat 274.

  To enhance the bond between the adhesive layer (or conductive layer 14 without the adhesive layer) and the substrate 260, heat or pressure can be used in the lamination process.

  Due to the difference in the affinity of the conductive layer 14 for the flexible donor film 240 and the selected substrate 260, the release layer 244 is not necessary. For example, the conductive layer 14 may have a much higher affinity for glass than the fabric donor film. In that case, after the lamination step, the fabric donor film can be removed, while the conductive layer 14 is firmly bonded to the glass substrate.

  Patterned transfer is possible in the lamination process. For example, the substrate 260 can be heated with a temperature gradient, which results in heated and unheated regions on the substrate 260 that follow a predetermined pattern. Due to the enhanced affinity (eg, adhesion), only the heated region is laminated with the conductive layer 14, thereby providing the patterned conductive layer 14 on the substrate 260. The heating region on the substrate 260 can be generated by, for example, a nichrome wire heater located directly below the substrate region to be heated.

  Patterned transfer can operate with a pressure gradient based on the pressure sensitive affinity exhibited by certain matrix materials or adhesives. For example, a patterned laminating roller can be used to apply different pressures according to a predetermined pattern. In addition, the patterned laminating roller can be heated to promote an affinity difference between the pressurized and non-pressurized areas.

  Prior to the lamination step, the conductive layer 14 can be cut (for example, punched out) in advance according to a predetermined pattern. After the pre-cut conductive layer 14 is transferred to the substrate 260, the predetermined pattern of the conductive layer 14 is retained, and the rest is removed along the pre-cut contour.

  The transparent conductor 16 can now be used as an electrode in a wide variety of devices, including any device that uses a transparent conductor 16 such as a metal oxide film. Examples of suitable devices include flat panel displays, LCDs, touch screens, electromagnetic shields, functional glasses (eg, for electrochromic windows), optoelectronic devices, and the like. In addition, the transparent conductors herein can be used in flexible devices such as flexible displays and touch screens.

  The transparent conductor 16 forms part of the touch screen. A touch screen is an interactive input device that is integrated into an electronic display and allows a user to input information by touching the screen. The touch screen is optically transparent and transmits light and images.

  Transparent conductor structures, their electrical and optical properties, and manufacturing methods are described in more detail in the following non-limiting examples.

  In this embodiment, when the metal nanowire dispersion layer 50 is applied onto the film 12 by using the slot die coater 54, the surface resistance in the MD direction and the TD direction of the transparent conductor 16 when the shear rate is changed is shown. It is a change.

[Example 1]
<Synthesis of silver nanowires>
In the presence of poly (vinyl pyrrolidone) (PVP), silver nitrate dissolved in ethylene glycol is reduced, and then, for example, Y.C. Sun, B.D. Gates, B.B. Mayers & Y. By performing the “polyol” method described in Xia “Crystalline silver nanowires by soft solution processing”, Nanoletters (2002), 2 (2) 165-168, Silver nanowires were synthesized. The silver nanowires had a width of about 70 nm to 80 nm and a length of about 8 μm.

<Silver nanowire dispersion coating solution>
The coating solution of the silver nanowire dispersion was about 0.08 wt% HPMC, about 0.36 wt% silver nanowire, about 0.005 wt% Zonyl® FSO-100, and about 99. Prepared by mixing 555 wt% water. In the first stage, an HPMC stock solution was prepared. An amount of water corresponding to about 3/8 of the desired total volume in the nanowire dispersion was placed in a beaker and heated on a hot plate to 80-85 ° C. Enough HPMC solution to bring the HPMC to 0.5 wt% was added to the water and the hot plate was cut. The mixture of HPMC and water was stirred to disperse the HPMC. The remainder of the total amount of water was cooled on ice, then added to the heated HPMC solution and stirred at high RPM for about 20 minutes. The HPMC solution was filtered through a 40 μm / 70 μm (absolute / nominal) Cuno Betapure filter to remove insoluble gels and particles. Next, a stock solution of Zonyl (registered trademark) FSO-100 was prepared. More specifically, 10 g of Zonyl® FSO100 was added to 92.61 mL of water and heated until the Zonyl FSO100 was completely dissolved. In the final ink composition, the amount of HPMC stock solution required to make an approximately 0.08 wt% HPMC solution was placed in a container. Thereafter, the amount of deionized water necessary to make an approximately 99.555 wt% aqueous solution in the final ink composition was added. The solution was stirred for about 15 minutes and the amount of silver nanowire needed to make an about 0.36% Ag nanowire solution in the final ink composition was added. Finally, the amount of Zonyl® FSO-100 stock solution required to make an approximately 0.005 wt% Zonyl® FSO-100 solution was added. The concentration of silver nanowires (AgNW) was about 0.5% w / v of the dispersion and the optical density was about 0.5 (measured with a Spectra Max M2 plate reader from Molecular Devices).

<Application of coating solution (silver nanowire dispersion)>
As the film 12, an Autoflex EBG5 polyethylene terephthalate (PET) film having a thickness of 5 μm was used. A PET film is an optically transparent insulator. The light transmittance and haze of the PET film are 91.6% and 0.78%. Unless otherwise specified, the light transmittance was measured by the method of ASTM D1003. Prior to application of the coating solution (nanowire dispersion), the film was treated with argon plasma.
Then, the silver nanowire dispersion was coated on the PET film by applying a coating solution of the silver nanowire dispersion onto the film 12 using the slot die coater 54.
At this time, the transport speed (coating speed) of the PET film when coating the coating liquid on one main surface of the PET film (the surface facing the head tip 62) is v [m / s], and the head tip 62 of the slot die 52 is used. When the gap between the PET film and one main surface of the PET film is g [m], the shear rate indicated by v / g [1 / s] is set to 100 [1 / s] and the coating solution is applied onto the PET film. did. In addition, the space | interval g was made into the range of 50-250 micrometers.

<Preparation of transparent conductor>
Thereafter, the silver nanowire dispersion on the PET film was dried to evaporate water in the silver nanowire dispersion to form a silver nanowire network layer. That is, a film (silver nanowire network layer) in which silver nanowires were exposed was formed on a PET film.
Then, after pressurizing with a pair of rollers with respect to the silver nanowire network layer on PET film, the matrix material was coat | covered to the silver nanowire network layer.
The matrix material was prepared by mixing polyurethane (PU) (Minwax quick-drying polyurethane) in methyl ethyl ketone (MEK) to form a 1: 4 (v / v) viscous solution. The matrix material was coated with spin coating on a bare silver nanowire film. Other methods known in the art can be used, such as doctor blades, Meyer rods, draw-downs or curtain coatings. The matrix material was cured at room temperature for about 3 hours, during which time the solvent MEK evaporated and the matrix material became hard. Alternatively, curing can occur in an oven, for example, at a temperature of 50 ° C. for about 2 hours.
Thus, the transparent conductor (AgNW / PU / PET) according to Example 1 having the conductive layer 14 on the PET film was produced. The conductive layer 14 of silver nanowires in the matrix 18 was about 100 nm thick.

[Examples 2 to 9]
Except that using a slot die coater having a slot die, the shear rate when applying the coating solution on the PET film was set to 1000, 2000, 3000, 5000, 7000, 8000, 9000 and 10000 [1 / s]. Transparent conductors according to Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, Example 8 and Example 9 were produced in the same manner as Example 1 described above.

[Reference Examples 1 and 2]
The embodiment described above, except that a slot die coater having a slot die was used, and the shear rate when applying the coating solution on the PET film was made less than 100 [1 / s] and greater than 10000 [1 / s]. In the same manner as in Example 1, transparent conductors according to Reference Example 1 and Reference Example 2 were produced.

[Evaluation]
The surface resistance value in the MD direction and the surface resistance value in the TD direction of the produced transparent conductor were measured, and the surface resistance value was 100 ohm / sq. Less than ◎, 100 ohm / sq. 200 ohm / sq. Less than ○, 200 ohm / sq. The above was evaluated as Δ, and the conductivity isotropic property was evaluated from the difference (absolute value) between the surface resistance value in the MD direction and the surface resistance value in the TD direction. Specifically, the difference (absolute value) between the surface resistance value in the MD direction and the surface resistance value in the TD direction is A, and the larger value among the surface resistance value in the MD direction and the surface resistance value in the TD direction is B. When (A / B) × 100 (%) was calculated, 90% or more was evaluated as ◎, less than 90% was evaluated as 80% or more, and less than 80% was evaluated as Δ. The evaluation results are shown in Table 1 below.

  From this evaluation result, when a coating solution (silver nanowire dispersion) is applied to one main surface of a PET film using a slot die coater having a slot die, a shear rate of 100 [1 / s] or more and 10000 [ 1 / s] or less, it can be seen that the conductivity of the transparent conductor 10 is improved and the isotropy of the conductivity is also improved. In particular, by setting the shear rate in the range of 3000 [1 / s] or more and 7000 [1 / s] or less, the conductivity of the transparent conductor 16 is greatly improved and the conductivity isotropic is also greatly improved. It can be seen that

  In addition, the manufacturing method of the transparent conductor which concerns on this invention is not restricted to the above-mentioned embodiment, Of course, various structures can be taken, without deviating from the summary of this invention.

DESCRIPTION OF SYMBOLS 10 ... Metal nanowire 12 ... Film 14 ... Conductive layer 16 ... Transparent conductor 18 ... Matrix 50 ... Metal nanowire dispersion layer 52 ... Slot die 54 ... Slot die coater 62 ... Head tip 64 ... Coating liquid 114 ... Metal nanowire network Layer 116 ... Matrix material layer 166 ... Coating solution 186 ... Lower roller 187 ... Upper roller

Claims (5)

In a method for producing a transparent conductor comprising a conductive layer containing a plurality of metal nanowires,
A preparation step of preparing a coating solution containing the plurality of metal nanowires;
A coating step of coating the coating liquid on one main surface of the film,
The coating step is performed using a slot die coater having a slot die,
When the coating liquid is applied to one main surface of the film, the conveyance speed (application speed) of the film is v [m / s], and the distance between the head end of the slot die and the one main surface of the film. A method for producing a transparent conductor, wherein a shear rate indicated by v / g [1 / s] is 100 to 10,000 [1 / s] when g [m] is designated. In the manufacturing method of the transparent conductor according to claim 1,
The method for producing a transparent conductor, wherein the shear rate is 3000 to 7000 [1 / s]. In the manufacturing method of the transparent conductor of Claim 1 or 2,
A method for producing a transparent conductor, wherein a distance between a head end of the slot die and the one main surface of the film is 50 to 250 μm. In the manufacturing method of the transparent conductor of any one of Claims 1-3,
The length of the said metal nanowire is 1-100 [micrometers], The manufacturing method of the transparent conductor characterized by the above-mentioned. In the manufacturing method of the transparent conductor according to claim 1,
The method for producing a transparent conductor, wherein the coating solution has a viscosity range of 1 to 100 cP.

Images