JP6753300B2 - Manufacturing method of transparent conductor - Google Patents

Description

The present invention relates to a method for producing a transparent conductor, and more particularly to a method for producing a transparent conductor capable of achieving both improvement in conductivity and low haze.

Conventionally, photolithography technology has been widely used as a method for forming a fine line pattern made of a conductive material. However, the photolithography technique has a lot of material loss and the process is complicated. Therefore, a method with less material loss and a simple process is being studied.

For example, there is a method of forming a fine line pattern by applying droplets containing a conductive material to a base material by an inkjet method. However, in the inkjet method, the width of the fine line is usually not smaller than the diameter of the ejected droplet, and it is not possible to form a fine line pattern having a line width of several μm.

As an approach for forming fine lines by the inkjet method, after applying a repellent to the entire surface of the base material in advance, a part of the repellent is hydrophilized with a laser or the like to form a repellent pattern, and droplets are applied to the repellent pattern. There is a method of forming a thin line. However, this method is complicated because it requires application of a repellent agent and formation of a repellent pattern by a laser.

Patent Document 1 discloses a method of forming a fine pattern by depositing a conductive material in a droplet applied on a substrate on a peripheral portion of the droplet by a coffee stain phenomenon. According to this method, it is possible to form a thin line having a width of several μm, which is smaller than the diameter of the droplet, without requiring a special step.

Further, Patent Document 2 discloses a method of forming a ring having a fine width made of conductive fine particles by utilizing the coffee stain phenomenon and connecting a plurality of the rings to form a transparent conductive film. However, in order to secure a conductive path in the transparent conductive film, it is necessary to increase the number of intersections of the rings. In this case, there is a limit to transparency because the intersections are particularly easy to see.

On the other hand, the applicant discloses a transparent conductive film having a conductive thin line pattern in Patent Document 3. Here, the conductive thin wire pattern is composed of a set of two conductive thin wires (parallel lines) parallel to each other. According to such a transparent conductive film, both transparency and conductivity can be achieved.

Japanese Unexamined Patent Publication No. 2005-95787 WO2011 / 051952 Japanese Unexamined Patent Publication No. 2014-38992

However, in the conventional technique, when the transparent conductor as a whole including the conductive thin line pattern (transparent conductive film) and the base material is viewed, the firing treatment is performed in order to achieve both improvement in conductivity and low haze. There was room for further improvement in the specific methods including this.

Therefore, an object of the present invention is to provide a method for producing a transparent conductor that can achieve both improvement in conductivity and reduction in haze.

Further, other problems of the present invention will be clarified by the following description.

The above problems are solved by the following inventions.

1.
A line-shaped liquid is formed on a transparent film substrate using an ink containing a conductive material.
Next, when the linear liquid is dried, the conductive material is selectively deposited on both ends in the line width direction of the linear liquid to form a conductive fine line pattern.
Next, the surface resistivity of the conductive fine wire pattern is 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less, and the haze value of the transparent film substrate is 2% or less. After firing
Next, a method for producing a transparent conductor, which comprises forming a metal film on the conductive thin wire pattern by plating to obtain a transparent conductor.
2.
The method for producing a transparent conductor according to 1, wherein the firing treatment is performed by light irradiation or heat treatment.
3.
The firing process is
The temperature rises at a rate of 10 ° C / min to 50 ° C / min.
Then, it was held at a holding temperature of 100 ° C. to 130 ° C. and a holding time of 5 to 60 minutes.
The method for producing a transparent conductor according to 1 above, wherein the transparent conductor is then subjected to a heat treatment for lowering the temperature at a temperature lowering rate of 5 ° C./min or more.
4.
The method for producing a transparent conductor according to the above 1, wherein the firing treatment is performed by wavelength-controlled infrared irradiation.
5.
The method for producing a transparent conductor according to the above 1, wherein the firing treatment is performed by irradiation with a xenon flash.
6.
The method for producing a transparent conductor according to any one of 1 to 5, wherein the transparent film base material is polyethylene terephthalate.

According to the present invention, it is possible to provide a method for producing a transparent conductor that can achieve both improvement in conductivity and reduction in haze.

The figure which conceptually explains the formation method of the conductive pattern The figure explaining the first aspect of mesh pattern formation The figure explaining the second aspect of the mesh pattern formation

Hereinafter, embodiments for carrying out the present invention will be described.

In the method for producing a transparent conductor of the present invention, a line-shaped liquid is formed on a transparent film base material using an ink containing a conductive material, and then when the line-shaped liquid is dried, the line-shaped liquid is used. The conductive material is selectively deposited on both ends in the line width direction to form a conductive fine wire pattern, and then the surface specific resistance of the conductive fine wire pattern is 1.0 × 10 ² Ω / □ or more 1.0 × 10 ⁶ Ω / □ or less, and subjecting the calcined as haze value of the transparent film substrate is 2% or less processing, then the transparent conductor by forming a metal film on the electroconductive thin line pattern on the plating obtain.

When the line-shaped liquid is dried, the surface of the conductive fine wire pattern formed by selectively depositing the conductive material on both ends in the line width direction of the line-shaped liquid is subjected to a normal firing treatment. The specific resistance drops significantly to less than 1.0 × 10 ² Ω / □. On the other hand, in the present invention, the surface resistivity of the conductive fine wire pattern is not intentionally lowered to a high value of 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less. Moreover, the firing treatment is performed so that the haze value of the transparent film base material is 2% or less.

By such a firing treatment, for example, bleed-out and precipitation of components having a relatively low degree of polymerization (for example, an oligomer) contained in the resin constituting the transparent film base material are prevented, and a transparent film base material having excellent flexibility is obtained. When used, low haze can be realized and optical characteristics can be improved.

Further, the conductive thin wire pattern after the firing treatment exhibits excellent plating suitability even if the surface resistivity is as high as 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less. I found out that As a result, plating proceeds favorably, and a metal film can be uniformly formed on the conductive thin line pattern. As a result, the excellent conductivity required for a transparent conductor can be suitably imparted.

In this way, it is possible to obtain the effect of both improving the conductivity of the transparent conductor and reducing the haze.

Hereinafter, embodiments for carrying out the present invention will be described in more detail with reference to the drawings.

<Formation of conductive pattern>
FIG. 1 is a diagram conceptually explaining a method of forming a conductive pattern.

First, as shown in FIG. 1A, a transparent film base material (hereinafter, also simply referred to as a base material) 1 is prepared. Examples of the material of the film include resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, acrylic, polyester, polyamide, polycarbonate, and cycloolefin polymer, and from the viewpoint of significantly exerting the effects of the present invention, polyethylene is particularly used. Terephthalate and the like are suitable. As such a resin, for example, a resin obtained by subjecting a monomer, an oligomer or a prepolymer to a polymerization reaction (synthetic resin) can be used.

If necessary, the base material 1 can be surface-treated. Examples of the surface treatment include corona discharge treatment and the like. Further, if necessary, an undercoat layer can be formed on the surface of the base material 1. Examples of the undercoat layer include a resin layer and the like. Examples of the resin include polyester resin and the like. The undercoat layer can contribute to, for example, improving the adhesion of the conductive thin line pattern to the base material 1.

Next, as shown in FIG. 1B, a line-shaped liquid 2 is formed on the base material 1 using an ink containing a conductive material.

As the conductive material to be contained in the ink, for example, conductive fine particles, a conductive polymer and the like can be preferably exemplified.

The conductive fine particles are not particularly limited, but Au, Pt, Ag, Cu, Ni, Cr, Rh, Pd, Zn, Co, Mo, Ru, W, Os, Ir, Fe, Mn, Ge, Sn, Ga, Fine particles such as In can be preferably exemplified, and among them, metal fine particles such as Au, Ag, and Cu are preferable because they can form fine wires having low electrical resistance and resistance to corrosion. From the viewpoint of cost and stability, metal fine particles containing Ag are most preferable. The average particle size of these metal fine particles is preferably in the range of 1 to 100 nm, more preferably in the range of 3 to 50 nm. The average particle size is the volume average particle size, and can be measured by "Zetasizer 1000HS" manufactured by Malvern.

It is also preferable to use carbon fine particles as the conductive fine particles. As the carbon fine particles, graphite fine particles, carbon nanotubes, fullerenes and the like can be preferably exemplified.

The conductive polymer is not particularly limited, but a π-conjugated conductive polymer can be preferably mentioned. Examples of the π-conjugated conductive polymer include polythiophenes, polypyrroles, polyindoles, polycarbazoles, polyanilines, polyacetylenes, polyfurans, polyparaphenylenes, polyparaphenylene vinylenes, and polyparaphenylene sulfides. , Polyazulenes, polyisothianaphenes, polythiazyl and other chain conductive polymers can be used. Among them, polythiophenes and polyanilines are preferable, and polyethylenedioxythiophene is most preferable, because high conductivity can be obtained.

The conductive polymer more preferably contains the above-mentioned π-conjugated conductive polymer and polyanion. Such a conductive polymer can be easily produced by chemically oxidizing and polymerizing a precursor monomer forming a π-conjugated conductive polymer in the presence of an appropriate oxidizing agent, an oxidation catalyst, and a polyanion.

Commercially available materials can also be preferably used as the conductive polymer. For example, conductive polymers consisting of poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid are available from HC Starck as the "CLEVIOS series" and from Aldrich as "PEDOT-PASS483095" and "PEDOT-PASS560598". It is marketed as "Denatron series" by Nagase Chemtex. In addition, polyaniline is commercially available from Nissan Chemical Industries, Ltd. as the "ORMECON series".

The concentration of the conductive material in the ink can be, for example, 5% by weight or less, and further 0.01% by weight or more and 1.0% by weight or less. As a result, the coffee stain phenomenon, which will be described later, is more stably generated, and the conductive thin wire can be further thinned and the transparency can be further improved.

The solvent used for the ink is not particularly limited, and may include one or more selected from water and organic solvents.

The organic solvent is not particularly limited, but for example, alcohols such as 1,2-hexanediol, 2-methyl-2,4-pentanediol, 1,3-butanediol, 1,4-butanediol, propylene glycol, etc. Examples thereof include ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether.

Further, the ink may contain various additives such as a surfactant. The surfactant is not particularly limited, but for example, a silicon-based surfactant or the like can be used. The silicon-based surfactant is a side chain or terminal of dimethylpolysiloxane modified with polyether. For example, "KF-351A" and "KF-642" manufactured by Shin-Etsu Chemical Co., Ltd. and "BYK347" manufactured by Big Chemie. , "BYK348" and the like are commercially available. The concentration of the surfactant in the ink can be, for example, 1% by weight or less.

When forming the line-shaped liquid 2, a printing method can be preferably used, and an inkjet method is particularly preferable. When the inkjet method is used, the liquid containing the conductive material is discharged as droplets from the nozzle of the inkjet head while moving the inkjet head relative to the base material, and the discharged droplets are united on the base material. Can be allowed to form a linear liquid. The droplet ejection method of the inkjet head is not particularly limited, and for example, a piezo method, a thermal method, or the like can be used.

Next, when the linear liquid 2 is dried, the conductive material is selectively deposited on both ends of the linear liquid 2 in the line width direction (that is, both edges along the length direction of the linear liquid 2). As shown in 1 (c), a conductive thin line pattern composed of conductive thin lines 3 and 3 can be formed.

When the line-shaped liquid 2 is dried, a method of heating the surface of the base material 1 to a predetermined temperature, a method of blowing air, and the like can be combined.

The coffee stain phenomenon can be preferably used when the conductive material is selectively deposited on both ends of the line-shaped liquid 2 in the line width direction. Specifically, when the line-shaped liquid 2 is dried, the conductive material is selectively deposited on both ends of the line-shaped liquid 2 in the line width direction by the internal flow of the line-shaped liquid 2, so that the line-shaped liquid 2 is more than the line-shaped liquid 2. It is possible to form a conductive thin wire pattern composed of conductive thin wires 3 and 3 having a narrow wire width. By making the line width of the line-shaped liquid 2 constant, it is possible to form a parallel line pattern composed of conductive thin wires 3 and 3 parallel to each other as a conductive pattern.

The line width of the conductive thin wire 3 can be, for example, 10 μm or less, and further can be 8 μm or less. The lower limit of the line width of the conductive thin wire 3 is not particularly limited, but can be set to 1 μm or more, for example, from the viewpoint of imparting stable conductivity. Further, the film thickness of the conductive thin wire can be, for example, 500 nm or less. When the conductive thin wire has such a thin film thickness, the reduction of the surface resistivity of the conductive fine wire pattern by the firing treatment in the subsequent stage proceeds more quickly.

For example, by forming a plurality of line-shaped liquids on the base material, various conductive fine line patterns can be formed. The form of the conductive thin line pattern is not particularly limited, and examples thereof include a stripe pattern and a mesh pattern. The first aspect of mesh pattern formation will be described below with reference to FIG. 2, and then the second aspect of mesh pattern formation will be described with reference to FIG.

[First aspect of mesh pattern formation]
In the first aspect of mesh pattern formation, first, as shown in FIG. 2A, a plurality of line-shaped liquids 2 arranged side by side at predetermined intervals are formed on the base material 1.

Next, as shown in FIG. 2B, a pair of conductive thin wires 3 and 3 are formed from each of the line-shaped liquids 2 by utilizing the coffee stain phenomenon when the line-shaped liquid 2 is dried.

Next, as shown in FIG. 2C, a plurality of line-shaped liquids 2 arranged side by side at predetermined intervals are formed so as to intersect with the plurality of conductive thin wires 3 formed earlier.

Next, as shown in FIG. 2D, a pair of conductive thin wires 3 and 3 are formed from each of the line-shaped liquids 2 by utilizing the coffee stain phenomenon when the line-shaped liquid 2 is dried. The mesh pattern can be formed as described above.

In the example of FIG. 2, the linear liquid 2 and the conductive thin wire 3 are straight lines, but the present invention is not limited to this. The shapes of the linear liquid 2 and the conductive thin wire 3 may be, for example, a wavy line or a broken line.

[Second aspect of mesh pattern formation]
In the second aspect of mesh pattern formation, first, as shown in FIG. 3A, the base material 1 is placed on the base material 1 in the longitudinal direction (vertical direction in the figure) and the width direction (horizontal direction in the figure). ) Are arranged side by side at predetermined intervals to form a line-shaped liquid 2 forming a plurality of quadrangles.

Next, as shown in FIG. 3 (b), when the line-shaped liquid 2 is dried, the coffee stain phenomenon is utilized to form a thin wire unit composed of a pair of conductive thin wires 3 and 3 from each of the line-shaped liquid 2. Form. In such a thin wire unit, one of the conductive thin wires 3 and 3 (outer conductive thin wire 3) includes the other (inner conductive thin wire 3) inside, and the conductive thin wires 3 and 3 are formed concentrically. Further, the conductive thin wires 3 and 3 each form a quadrangle corresponding to the shapes of both edges (inner peripheral edge and outer peripheral edge) of the linear liquid 2.

Next, as shown in FIG. 3C, a plurality of quadrangular line-shaped liquids 2 arranged side by side at predetermined intervals in the longitudinal direction and the width direction of the base material 1 are formed on the base material 1. Here, the line-shaped liquid 2 forming a plurality of quadrangles is formed at a position sandwiched between the previously formed thin wire units. Here, the linear liquid 2 forming a quadrangle is arranged so as to come into contact with the outer conductive thin wire 3 of the thin wire units adjacent thereto, but not to contact the inner conductive thin wire 3.

Next, as shown in FIG. 3D, when the line-shaped liquid 2 is dried, the coffee stain phenomenon is utilized to form a thin wire unit composed of a pair of conductive thin wires 3 and 3 from each of the line-shaped liquids 2. Further form.

In the pattern shown in FIG. 3D, the outer conductive thin wires 3 are connected to each other with the adjacent outer conductive thin wires 3. On the other hand, the inner conductive thin wire 3 is not connected to the other inner conductive thin wire 3 and the outer conductive thin wire 3. That is, the inner conductive thin wires 3 are arranged so as to be isolated.

The pattern shown in FIG. 3D may be used as it is as a mesh pattern. Further, the inner conductive thin wire 3 in the pattern shown in FIG. 3 (d) may be removed to form a mesh pattern (FIG. 3 (e)) composed of the outer conductive thin wire 3. According to the second aspect of mesh pattern formation, the effect of forming the conductive thin wire 3 with a high degree of freedom can be obtained. In particular, it is possible to obtain an effect that the arrangement interval of the plurality of conductive thin wires 3 can be set with a high degree of freedom without depending on the line width of the linear liquid 2.

The method for removing the inner conductive thin wire 3 is not particularly limited, and for example, a method of irradiating an energy ray such as a laser beam, a method of chemically etching, or the like can be used.

Further, when electroplating the outer conductive thin wire 3, a method of removing the inner conductive thin wire 3 with a plating solution may be used. As described above, the inner conductive thin wire 3 is arranged so as to be isolated, and can be excluded from the energization path for electrolytically plating the outer conductive thin wire 3. Therefore, while the outer conductive thin wire 3 is electrolytically plated (while energized), the inner conductive thin wire 3 that is not electrolytically plated can be dissolved or decomposed and removed by the plating solution. it can.

In the example of FIG. 3, the linear liquid 2 and the conductive thin wire 3 are formed into a quadrangle, but the present invention is not limited to this. Examples of the shapes of the linear liquid 2 and the conductive thin wire 3 include a closed geometric figure. Examples of closed geometric figures include polygons such as triangles, quadrilaterals, hexagons, and octagons. Also, closed geometric figures can include curved elements such as circles, ellipses and the like.

The obtained conductive thin wire pattern is subjected to a firing treatment and then plated as described in detail below.

<Baking process>
The firing treatment includes a conductive thin wire pattern having a surface specific resistance (hereinafter, also referred to as sheet resistance) of 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less, and a conductive fine wire pattern. It is applied so that the haze value of the base material is 2% or less. For example, when the haze value increases with the firing treatment, the amount of increase (change amount) is preferably suppressed to, for example, 1% or less.

The surface resistivity (Ω / □) of the conductive thin wire pattern can be measured using "Loresta-AX" manufactured by Mitsubishi Chemical Analytech Co., Ltd., and is the measured value measured at 5 points in the conductive thin wire pattern. It can be an average value.

The haze value (%) of the base material containing the conductive fine line pattern is based on JIS K7136, and the haze meter "NDH 7000" manufactured by Nippon Denshoku Kogyo Co., Ltd. is used to determine the haze value (%) of the base material portion without the conductive pattern. It is a value obtained by measuring the haze of.

The firing treatment can be performed by various methods within a range in which the surface resistivity and the haze value satisfy the above-mentioned conditions. It is particularly preferable to perform light irradiation or heat treatment as the firing treatment.

The light irradiation is not particularly limited as long as it irradiates electromagnetic waves, and examples thereof include a method of irradiating gamma rays, X-rays, ultraviolet rays, visible light, infrared rays (IR), microwaves, and radio waves.

A preferred embodiment of light irradiation is, first, wavelength-controlled infrared irradiation. As a result, energy absorption by the transparent film base material can be suppressed. For infrared wavelength control, for example, a method such as covering the outer periphery of a light source (for example, a filament) that generates infrared rays with a member (for example, a tube or a plate) that absorbs infrared rays having a predetermined wavelength or higher can be used. As a result, infrared rays having a wavelength less than a predetermined wavelength can be irradiated. At this time, in order to suppress the rise in the surface temperature of the heater, a cooling gas can be brought into contact with the member. The members may be provided in duplicate so that a cooling gas can flow through these gaps.

As the wavelength control of infrared rays, it is possible to cut a part or all of the wavelength region where energy absorption by the transparent film substrate occurs. As a result, energy absorption by the transparent film base material is suppressed. In particular, it is preferable to select and irradiate a wavelength at which energy absorption by the transparent film substrate does not substantially occur. Such a wavelength can be appropriately selected depending on the substrate. For example, when the base material is a PET film, energy absorption by the base material does not occur by selecting a wavelength of 3.5 μm or less.

Further, as another preferable mode of light irradiation, there is a method of pulsing electromagnetic waves. This makes it possible to prevent the base material from being heated to a high temperature while the conductive material applied on the base material efficiently absorbs energy. As a result, only the conductive material can be instantaneously heated to a very high temperature and fired. In particular, xenon flash irradiation is preferable because it has excellent firing efficiency. For the xenon flash irradiation, a method of causing the xenon lamp to emit light in pulses can be used.

As a preferred embodiment of the heat treatment, the temperature is raised at a heating rate of 10 ° C./min to 50 ° C./min, then held at a holding temperature of 100 ° C. to 130 ° C. and a holding time of 5 to 60 minutes, and then a temperature lowering rate of 5 ° C./min. The temperature can be lowered in more than a minute.

When the rate of temperature rise is 10 ° C./min or more, bleed-out of the oligomer component in the substrate is prevented, and an increase in the haze value is suppressed. Further, when the temperature rising rate is 50 ° C./min or less, the temperature control when the holding temperature is reached becomes easy, and for example, it is prevented that the temperature exceeds the holding temperature.

When the holding temperature is 100 ° C. or higher, good conductivity can be exhibited regardless of the type of the conductive material. Further, when the holding temperature is 130 ° C. or lower, bleed-out of the oligomer component in the base material is prevented, and an increase in haze is suppressed.

When the holding time is 5 minutes or more, the conductivity is suitably improved. Further, when the holding time is 60 minutes or less, the effect of improving the productivity can be obtained.

When the temperature lowering rate is 5 ° C./min or more, the bleed-out of the oligomer component in the substrate is prevented, and the increase in the haze value is suppressed. Further, even when a particularly thin base material is used, the occurrence of wrinkles in the cooling process is preferably prevented.

For the heat treatment, for example, hot air, a heating stage, a heating press and the like are used, and hot air is particularly preferable. If hot air is used, the conductive fine wire patterns formed on both sides of the base material can be suitably fired at the same time. Further, if hot air is used, an effect that the rate of temperature rise and the like can be easily controlled can be obtained. In particular, by using a roll transporter for transporting a base material and a hot air furnace in combination, the temperature rise rate and holding time can be easily controlled by setting the roll transport speed and the furnace length.

<Plating>
Examples of the plating include electrolytic plating and electroless plating. In particular, when electrolytic plating is used, it is easy to selectively form a metal film on the conductive thin wire pattern by utilizing the conductivity of the conductive fine wire pattern.

The metal constituting the metal film may be the same as the conductive material forming the conductive thin line pattern, but is preferably different. For example, the conductive fine wire pattern can be made of silver, and the metal film can be made of copper, nickel, chromium, or the like.

It is also preferable to perform electroplating a plurality of times with different plating metals. As a result, a plurality of metal films can be laminated on the conductive thin line pattern. For example, a first metal film made of copper and a second metal film made of nickel or chromium can be formed on the conductive thin wire pattern.

By forming a first metal film made of copper and a second metal film made of nickel or chromium on the conductive thin wire pattern, the effect of improving the conductivity by copper and the effect of improving the weather resistance by nickel or chromium are obtained. be able to. Further, by coating a metal having a strong color such as copper with nickel or chromium, the strong color disappears and the color becomes neutral, and the effect that the conductive fine line pattern is hard to see can be obtained.

<Transparent conductor>
As described above, a transparent conductor can be obtained. The transparent conductor is composed of a base material, a conductive fine wire pattern provided on the base material, and a metal film provided on the conductive fine wire pattern.

The fact that the transparent conductor is "transparent" means that the conductive thin lines are thinner than the line-shaped liquid due to the selective deposition of conductive materials at both ends in the line width direction of the line-shaped liquid, which is visible. It means that the sex is reduced. Therefore, the conductive material itself constituting the conductive thin wire does not have to be transparent, and a non-transparent conductive material can be preferably used.

The use of the transparent conductor is not particularly limited, and it can be used in various devices provided in various electronic devices.

For example, applications of transparent conductors include transparent electrodes for displays of various types such as liquid crystals, plasma, organic electroluminescence, and field emissions, touch panels, mobile phones, electronic paper, various solar cells, various electroluminescence dimming elements, and the like. Examples thereof include transparent electrodes used in the above. It is particularly preferable to use the transparent conductor as a touch panel sensor for electronic devices such as smartphones and tablet terminals. When used as a touch panel sensor, a mesh pattern composed of conductive thin wires can be used as the position detection electrodes (X electrode and Y electrode).

Examples of the present invention will be described below, but the present invention is not limited to such examples.

(Example 1)
1. Formation of a conductive fine line pattern When a line-shaped liquid is formed on a transparent film base material using an ink containing a conductive material, and then the line-shaped liquid is dried, both ends of the line-shaped liquid in the line width direction are formed. By selectively depositing the conductive material to form a conductive thin wire, a pattern composed of the conductive thin wire was formed.

Here, a polyethylene terephthalate film with an easy-adhesion layer having a thickness of 125 μm was used as the base material. Further, as an ink containing a conductive material, an ink composed of an aqueous dispersion of silver nanoparticles (silver nanoparticles: 40% by weight) 1.75% by weight, diethylene glycol monobutyl ether 20% by weight, and pure water (remaining portion) is used. There was.

In addition, an inkjet method was used to form the line-shaped liquid, and a mesh pattern was formed in the same manner as the method shown in FIG. Specifically, first, an XY robot (“SHOTMASTER300” manufactured by Musashi Engineering) equipped with an inkjet head “512LHX” (standard droplet capacity 42pL) manufactured by Konica Minolta and an inkjet control system (“IJCS-1” manufactured by Konica Minolta). The ink was sequentially ejected as droplets onto the base material 1 so that the pitch between the nozzle rows was 282 μm and the pitch between the scanning directions was 45 μm, and the ink was continuously applied on the base material 1 in the scanning direction. A plurality of first line-shaped liquids 2 were formed by coalescing the droplets (FIG. 2A). While printing, the stage on which the base material 1 is placed is heated at 70 ° C., and in the process of drying these line-shaped liquids 2, solids are deposited on the peripheral portion (edge) to conduct conductivity from one line segment 2. A first parallel line 4 composed of two conductive thin wires 3 and 3 containing a sex material was formed.

Then, the base material is rotated by 90 °, and a plurality of second line-shaped liquids 2 with ink are applied and dried in the direction orthogonal to the first parallel line 4 in the same manner as described above, and the second is The parallel lines 4 of the above were formed.

As a result, the mesh pattern (mesh-shaped conductive thin line pattern) as shown in FIG. 2D is formed by the conductive thin lines 4 and 4 formed from the first and second line-shaped liquids 2 and 2, respectively. Been formed.

2. Firing treatment The obtained conductive thin wire pattern was fired.

Here, as a firing treatment, a heat treatment was performed in which the temperature was raised at a heating rate of 32 ° C./min, then held at a holding temperature of 120 ° C. and a holding time of 10 minutes, and then lowered at a temperature lowering rate of 100 ° C./min. For the heat treatment, a hot air drying furnace equipped with a roll transfer device for transporting a substrate with a conductive fine wire pattern was used.

3. Plating The following electrolytic copper plating and the following electrolytic nickel plating were applied to the fired conductive wire pattern, and a copper plating layer and a nickel plating layer were formed in this order on the conductive fine wire pattern to obtain a transparent conductor. ..

<Electrolytic copper plating>
Conductivity immersed in a copper plating bath prepared by formulating 60 g of copper sulfate pentahydrate, 19 g of sulfuric acid, 2 g of 1N hydrochloric acid, and 5 g of a gloss-imparting agent ("ST901C" manufactured by Meltex) to 1000 ml with ion-exchanged water. The thin wire pattern was fed and electrolytic copper plating was performed. A copper plate for plating was used as the anode.

<Electrolytic nickel plating>
Power is supplied to a conductive fine wire pattern (the conductive fine wire pattern after electrolytic copper plating) immersed in a nickel plating bath prepared by preparing a formulation in which 240 g of nickel sulfate, 45 g of nickel chloride, and 30 g of boric acid are finished to 1000 ml with ion-exchanged water. Then, electrolytic nickel plating was performed. A nickel plate for plating was used as the anode.

4. Evaluation method The transparent conductor after plating was observed and evaluated according to the following evaluation criteria.
[Evaluation criteria]
◯: Plating is evenly applied to the entire surface.
X: Some parts are not plated.

The above results are shown in Table 1.

(Example 2)
In Example 1, as a firing treatment, a heat treatment in which the temperature is raised at a heating rate of 9.5 ° C./min, then held at a holding temperature of 120 ° C. and a holding time of 10 minutes, and then lowered at a temperature lowering rate of 100 ° C./min. A transparent conductor was produced in the same manner as in Example 1 except that the above was applied, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
In Example 1, as a firing treatment, a heat treatment is performed in which the temperature is raised at a heating rate of 52 ° C./min, then held at a holding temperature of 120 ° C. and a holding time of 10 minutes, and then lowered at a temperature lowering rate of 100 ° C./min. A transparent conductor was produced in the same manner as in Example 1 except for the above, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 4)
In Example 1, as a firing treatment, a heat treatment is performed in which the temperature is raised at a heating rate of 32 ° C./min, then held at a holding temperature of 95 ° C. and a holding time of 30 minutes, and then lowered at a temperature lowering rate of 100 ° C./min. A transparent conductor was produced in the same manner as in Example 1 except for the above, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
In Example 1, as a firing treatment, a heat treatment is performed in which the temperature is raised at a heating rate of 32 ° C./min, then held at a holding temperature of 135 ° C. and a holding time of 10 minutes, and then lowered at a temperature lowering rate of 100 ° C./min. A transparent conductor was produced in the same manner as in Example 1 except for the above, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
In Example 1, as a firing treatment, a heat treatment in which the temperature is raised at a heating rate of 32 ° C./min, then held at a holding temperature of 120 ° C. and a holding time of 10 minutes, and then lowered at a temperature lowering rate of 4.5 ° C./min. A transparent conductor was produced in the same manner as in Example 1 except that the above was applied, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
In Example 1, a transparent conductor was produced in the same manner as in Example 1 except that wavelength-controlled infrared irradiation was applied as a firing treatment, and the transparent conductor was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Here, for wavelength-controlled infrared irradiation, two quartz glass plates that absorb infrared rays with a wavelength of 3.5 μm or more are attached to an infrared irradiation device (ultimate heater / carbon) manufactured by Akira Kogyo Co., Ltd., and between the glass plates. A sample in which cooling air was flowed and the filament temperature was adjusted to 1200 ° C. and the surface temperature of the quartz glass plate was adjusted to 130 ° C. was used. A distance of 100 mm was provided between the base material and the heater. The irradiation time was 10 minutes.

(Example 8)
In Example 1, a transparent conductor was produced in the same manner as in Example 1 except that xenon flash irradiation was applied as a firing treatment, and the evaluation was carried out in the same manner as in Example 1. The results are shown in Table 1.

Here, a xenon flash firing device "Pulse Forge 1200" manufactured by NOVACENTRIX was used for the xenon flash irradiation. The irradiation conditions were set to a voltage of 400 V, a pulse width of 1000 μs, and an irradiation energy of 7,000 mJ / cm ² .

(Comparative Example 1)
In Example 1, as a firing treatment, a heat treatment is performed in which the temperature is raised at a heating rate of 5 ° C./min, then held at a holding temperature of 135 ° C. and a holding time of 30 minutes, and then lowered at a temperature lowering rate of 100 ° C./min. A transparent conductor was produced in the same manner as in Example 1 except for the above, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, as a firing treatment, a heat treatment is performed in which the temperature is raised at a heating rate of 23 ° C./min, then held at a holding temperature of 95 ° C. and a holding time of 10 minutes, and then lowered at a temperature lowering rate of 100 ° C./min. A transparent conductor was produced in the same manner as in Example 1 except for the above, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Evaluation>
The surface resistivity of the pattern made of conductive thin wires should be 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less, and the haze value of the pattern made of conductive thin wires should be 2% or less. It can be seen that Examples 1 to 8 subjected to the firing treatment can achieve both improvement in conductivity and reduction in haze in comparison with Comparative Examples 1 and 2.

1: Base material 2: Line-shaped liquid 3: Conductive thin wire

Claims (4)

A line-shaped liquid is formed on a transparent film substrate using an ink containing conductive fine particles.
Next, when the linear liquid is dried, the conductive fine particles are selectively deposited on both ends of the linear liquid in the line width direction to form a conductive fine line pattern having a line width of 1 μm or more and 10 μm or less.
Next, the temperature is raised at a heating rate of 10 ° C./min to 52 ° C./min, held at a holding temperature of 95 ° C. to 135 ° C., a holding time of 5 to 60 minutes, and lowered at a temperature lowering rate of 4.5 ° C./min or more. The surface specific resistance of the conductive fine wire pattern is 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less by performing a firing process, and the haze of the transparent film substrate accompanying the firing process. Increase the value by 1% or less
Next, a method for producing a transparent conductor, which comprises forming a metal film on the conductive thin wire pattern by plating to obtain a transparent conductor. A line-shaped liquid is formed on a transparent film substrate using an ink containing conductive fine particles.
Next, when the linear liquid is dried, the conductive fine particles are selectively deposited on both ends of the linear liquid in the line width direction to form a conductive fine line pattern having a line width of 1 μm or more and 10 μm or less.
Next, firing treatment is performed by wavelength-controlled infrared irradiation to make the surface resistivity of the conductive fine wire pattern 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less, and the firing treatment. The amount of increase in the haze value of the transparent film base material accompanying the above is set to 1% or less.
Next, a method for producing a transparent conductor, which comprises forming a metal film on the conductive thin wire pattern by plating to obtain a transparent conductor. A line-shaped liquid is formed on a transparent film substrate using an ink containing conductive fine particles.
Next, when the linear liquid is dried, the conductive fine particles are selectively deposited on both ends of the linear liquid in the line width direction to form a conductive fine line pattern having a line width of 1 μm or more and 10 μm or less.
Next, a firing treatment is performed by irradiation with a xenon flash so that the surface resistivity of the conductive fine wire pattern is 1.0 × 10 ² Ω / □ or more and 1.0 × 10 ⁶ Ω / □ or less, and the firing treatment is performed. Increase the haze value of the transparent film substrate by 1% or less.
Next, a method for producing a transparent conductor, which comprises forming a metal film on the conductive thin wire pattern by plating to obtain a transparent conductor. The transparent film base material is polyethylene terephthalate in which bleed-out is not prevented.
The ink has a concentration of the conductive fine particles of 5% by weight or less.
The method for producing a transparent conductor according to any one of claims 1 to 3, wherein the conductive fine particles are silver nanoparticles.

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