JP2006047720A - Method of forming transparent conductive film and transparent conductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a transparent conductive film which enables a transparent conductive film having a low resistance and a high visible light transmittance to be formed by irradiating a coating film with plasma in the atmosphere without requiring heat treatment or an evacuated atmosphere and is advantageous in mass productivity and cost because of the use of a coating method, and to provide the transparent conductive film. <P>SOLUTION: The method of forming a transparent conductive film is characterized in that a coating film 7 is formed by coating a substrate 6 with conductive paint, and reaction gas is introduced onto the coating film 7 under an atmospheric pressure to make the reaction gas into plasma P, and the coating film 7 is irradiated with the plasma P to be modified, whereby a transparent conductive film 9 is formed on the substrate 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a transparent conductive film and a transparent conductive film, and more specifically, a plasma display (PDP), a liquid crystal display (LCD), an electroluminescent display (EL), a cathode ray tube (CRT), and a projection (PJTV). The present invention relates to a technique capable of forming a transparent conductive film having a low resistance and a high visible light transmittance on the display surface of an image display device.

Conventionally, in an image display unit of an image display device such as a plasma display (PDP), a liquid crystal display (LCD), an electroluminescent display (EL), a cathode ray tube (CRT), a projection (PJTV), a glass substrate, an organic polymer film A flat panel in which a transparent conductive film is formed on a transparent substrate such as is used.
Conventionally, methods for forming a transparent conductive film on a transparent substrate can be roughly classified into two methods, a dry method and a wet method.

The dry method is a method of forming a transparent conductive film made of a metal or a metal oxide on a transparent substrate by a vacuum deposition method, an ion plating method, a sputtering method or the like (for example, see Non-Patent Documents 1 and 2). .
Further, the wet method is a method of forming a transparent conductive film by a coating method, a method of forming a metal oxide thin film on a transparent substrate by a sol-gel method using hydrolysis and condensation polymerization reaction of metal alkoxide, metal particles Or the method of apply | coating the coating liquid which disperse | distributed the metal oxide particle to the organic solvent on a transparent base material etc. are known (for example, refer patent document 1).
In order to stabilize the dispersion state of the particles and improve the in-plane uniformity of the obtained film, a coating solution using metal fine particles or metal oxide fine particles having a smaller particle diameter has been proposed. (For example, refer to Patent Document 2).
Kiyomura Takatoshi, Oki Tatsuma, Hoshi Yoichi, “Low-Temperature Deposition of ITO Thin Films by Sputter Beam Deposition”, IEICE Technical Report, The Institute of Electronics, Information and Communication Engineers, October 2000, CPM 2000-126 (2000-10) ), P. 59-64 Toshiyuki Sakami, Yoshihiro Ushigami, Kiyoshi Kurii, “ITO Film Formation Technology by Ion Plating”, Surface Technology, Surface Technology Association of Japan, September 1999, Vol. 50, No. 9, p. 782-785 JP-A-60-220507 Japanese Patent Laid-Open No. 11-31417

  By the way, with the conventional dry method, high-quality film formation is possible, but since a relatively high degree of vacuum is required, the manufacturing apparatus becomes quite expensive, resulting in an increase in film formation cost. There was a problem that the obtained transparent conductive film would be very expensive. In addition, since it is a batch type, the number of production per lot is limited, and it is difficult to increase productivity.

On the other hand, in the conventional wet method, since the coating film apparatus is inexpensive, an inexpensive transparent conductive film can be provided, and continuous production is possible, so that it is easy to increase productivity. However, there is a problem that it is difficult to use an organic polymer film as a transparent substrate because heat treatment is required to obtain desired conductivity.
For example, in the case of the sol-gel method, in order to obtain a desired conductivity, it is common to perform a heat treatment at a temperature of 300 to 400 ° C. or higher, and thus an organic polymer film that can withstand such a temperature. Is not currently available.
In addition, since the reactivity of the coating solution in the sol state as the coating solution is high and unstable, there is a problem that the in-plane uniformity of the film quality of the coating film using this coating solution is lowered. . Furthermore, since metal alkoxide is expensive, there also existed a problem that manufacturing cost will become high.

  In addition, the method using a coating solution is a method in which this coating solution is stable, relatively inexpensive and excellent in productivity, but there is a possibility that organic substances such as a binder component and a dispersant remain in the film, and a dry method. For example, it is difficult to connect the particles as described above, and thus it is necessary to fuse or weld the fine particles by heating at 250 ° C. or higher. Therefore, in the field of liquid crystal displays (LCD) using organic materials and organic electroluminescent displays (EL), there is a problem that they cannot be used due to heat resistance.

  The present invention has been made in order to solve the above-described problems. By irradiating the coating film with plasma in the air, it has low resistance and visible light without requiring heat treatment or a reduced-pressure atmosphere. A transparent conductive film having a high transmittance can be formed. Further, it is an object to provide a transparent conductive film forming method and a transparent conductive film which are excellent in mass productivity and cost by using a coating method. .

  As a result of intensive studies, the present inventors applied a conductive paint on a base material to form a coating film, and this coating film was irradiated with plasma generated under atmospheric pressure, whereby heat treatment was performed. It has been found that a transparent conductive film having low resistance and high visible light transmittance can be formed with good productivity and at low cost without requiring a reduced pressure atmosphere, and the present invention has been completed.

  That is, in the method for forming a transparent conductive film of the present invention, a conductive paint is applied on a substrate to form a coating film, and a reaction gas is introduced onto the coating film at atmospheric pressure to thereby apply the reaction gas. A transparent conductive film is formed on the substrate by making it into plasma and irradiating the coating film with the plasma to modify the coating film.

The reactive gas preferably contains one or more selected from the group of nitrogen, rare gas, oxygen, ozone, and hydrogen.
The reactive gas preferably contains one or more organometallic compounds.

  Controlling the flow of plasma irradiated to the coating film by applying a voltage between the electrode provided on the surface opposite to the coating film side of the substrate and the plasma generating electrode for generating the plasma It is preferable to do.

  The substrate is inclined with respect to the plasma irradiation direction, and between the electrode provided on the surface opposite to the coating film side of the substrate and the rectifying electrode provided facing the coating film. It is preferable to control the flow of plasma applied to the coating film by applying a voltage.

While moving the substrate with respect to the plasma irradiation direction, between the electrode provided on the surface of the substrate opposite to the coating film side and the rectifying electrode provided facing the coating film It is preferable to control the flow of plasma applied to the coating film by applying a voltage to the film.
The movement is preferably a rotational movement about an axis orthogonal to the plasma irradiation direction.
The voltage is preferably one or more selected from the group of a DC voltage, an AC voltage, a high frequency voltage, and a bipolar pulse voltage.

The substrate is preferably made of glass or an organic polymer compound.
The conductive paint preferably contains any one of an organic metal compound, a metal inorganic acid salt, a metal organic acid salt, a metal oxide fine particle, and a fine particle composed of a metal or an alloy.

  The transparent conductive film of the present invention is formed by the method for forming a transparent conductive film of the present invention.

According to the method for forming a transparent conductive film of the present invention, a conductive paint is applied onto a substrate to form a coating film, and a reaction gas is introduced onto the coating film at atmospheric pressure to thereby remove the reaction gas. A transparent conductive film is formed on the substrate by irradiating the plasma with the plasma and modifying the coating to modify the coating. Therefore, low resistance without requiring heat treatment or a reduced-pressure atmosphere. In addition, a transparent conductive film having a high visible light transmittance can be easily formed.
Moreover, since a coating film is formed by applying a conductive paint on a substrate, a transparent conductive film excellent in mass productivity and cost can be obtained.

According to the transparent conductive film of the present invention, since the transparent conductive film is formed by the method of forming a transparent conductive film of the present invention, it is possible to reduce the resistance and increase the visible light transmittance of the transparent conductive film without requiring heat treatment or a reduced pressure atmosphere. Can be planned.
In addition, since this transparent conductive film is a film modified by plasma irradiation, the in-plane uniformity of the film is improved, the surface resistance is low, and the visible light transmittance is achieved despite the thin film thickness. Can be high.

A method for forming a transparent conductive film and a best mode for carrying out the transparent conductive film of the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

  In the method for forming a transparent conductive film of the present invention, a conductive paint is applied on a substrate to form a coating film, and a reaction gas is introduced onto the coating film at atmospheric pressure to convert the reaction gas into plasma. The transparent conductive film is formed on the substrate by irradiating the coating film with the plasma and modifying the coating film.

"Conductive paint"
This conductive paint is an organic metal compound, metal inorganic acid salt, metal organic acid salt, metal oxide fine particles, metal / alloy fine particles (fine particles made of metal or alloy), or one or more of them are organic. It is a paint dissolved or dispersed in a solvent and / or water.
What is necessary is just to select suitably the thing containing the metal element to be used for the organometallic compound etc. to be used, and it is not specifically limited.

As the organometallic compound, for example, metal alkyl and metal aryl such as indium, tin, zinc, cadmium, gallium, antimony, and aluminum are preferably used, and metal acetylacetonate such as aluminum acetylacetonate is particularly suitable. It is.
As the metal inorganic acid salt, for example, nitrates, hydrochlorides, sulfates, and phosphates containing one or more of indium, tin, zinc, cadmium, gallium, antimony, and aluminum are preferably used. In place of the metal inorganic acid salt, a hydrate of the above-mentioned inorganic acid salt may be used.

  As the metal organic acid salt, a salt of a metal and a carboxylic acid such as a saturated aliphatic monocarboxylic acid, a saturated aliphatic dicarboxylic acid, an unsaturated fatty acid, a carbocyclic carboxylic acid, or a heterocyclic carboxylic acid is preferably used. , Acetate, tartrate, formate, oxalate, 2-ethylhexanoate, and the like containing any one or more of indium, tin, zinc, cadmium, gallium, antimony, and aluminum.

Examples of the metal oxide fine particles include fine particles such as indium oxide, tin oxide, zinc oxide, cadmium oxide, gallium oxide, antimony oxide, and aluminum oxide, or tin-added indium oxide obtained by adding other metal elements to these oxides. Fine particles such as (ITO), antimony-added tin oxide (ATO), zinc-added indium oxide (IZO) and aluminum-added zinc oxide (AZO) are preferably used.
In particular, metal oxides constituting the transparent conductive film include tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), and indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ) and the like are preferably used.

The average primary particle diameter of the metal oxide fine particles is preferably 1 nm or more and 100 nm or less, more preferably 1 nm or more and 30 nm or less.
The reason is that if the average primary particle diameter of the metal oxide fine particles is less than 1 nm, the crystallinity of the transparent conductive film is lowered, and as a result, the electrical conductivity of the film is lowered (surface resistance is raised). In addition, if it exceeds 100 nm, the transparency and sinterability of the transparent conductive film deteriorate.
Here, when the average primary particle diameter is 1 nm or more and 30 nm or less, the sinterability between the metal oxide fine particles is improved, and the densification of the coating film is facilitated.

Examples of the metal / alloy fine particles include fine particles such as indium, tin, zinc, cadmium, gallium, antimony, and aluminum, or fine particles such as indium-tin alloy, indium-zinc alloy, antimony-tin alloy, and zinc-aluminum alloy. Preferably used.
The average primary particle diameter of the metal / alloy fine particles is preferably 1 nm or more and 100 nm or less, more preferably 1 nm or more and 30 nm or less.
The reason is that when the average primary particle diameter of the metal / alloy fine particles is less than 1 nm, the crystallinity of the transparent conductive film is lowered, and as a result, the electrical conductivity of the film is lowered (surface resistance is raised). In addition, if it exceeds 100 nm, the transparency and sinterability of the transparent conductive film deteriorate.

  The organic solvent may be appropriately selected depending on the organic metal compound, metal inorganic acid salt, metal organic acid salt, metal oxide fine particles, metal or alloy fine particles used, and is not particularly limited. Monohydric alcohols such as methanol, ethanol, 2-propanol and butanol, dihydric alcohols such as ethylene glycol, ketones such as acetone, methyl ethyl ketone and diethyl ketone, esters such as ethyl acetate, butyl acetate and benzyl acetate, methoxy Examples include ether alcohols such as ethanol and ethoxyethanol, ethers such as dioxane and tetrahydrofuran, acid amides such as N, N-dimethylformamide, and aromatic hydrocarbons such as toluene and xylene.

  The amount of the organic solvent and / or water used is easy to apply depending on the organic metal compound, metal inorganic acid salt, metal organic acid salt, metal oxide fine particles, metal or alloy fine particles used and What is necessary is just to select suitably so that a film thickness can be obtained. For example, when metal oxide fine particles or metal / alloy fine particles are dissolved or dispersed in an organic solvent and / or water, the amount of fine particles is preferably 1 to 10% by weight based on the total amount of the solvent.

"Coating"
The conductive paint is applied onto a substrate to form a coating film.
It does not specifically limit as a base material, A glass substrate and a plastic substrate (organic polymer compound substrate) can be mentioned, As a shape, a flat plate, a film, a sheet | seat, etc. may be sufficient. As the plastic substrate, a transparent plastic sheet or a transparent plastic film is preferable.

The material of the plastic substrate is not particularly limited. For example, cellulose acetate, polystyrene (PS), polyethylene terephthalate (PET), polyether, polyimide, epoxy, phenoxy, polycarbonate (PC), polyvinylidene fluoride, etc. Can be appropriately selected.
Also, the thickness of the plastic substrate is not particularly limited, and a film of about 50 to 250 μm can be used for a film and a sheet of about 10 mm can be used for a sheet.

  These substrates may be used alone, or may be used as a substrate having a laminated structure in which a plurality of substrates are bonded and integrated. This substrate is preferably cleaned using a cleaning liquid such as pure water or an organic solvent before applying the conductive paint. If ultrasonic waves are applied to the cleaning liquid during this cleaning, the cleaning power is greatly improved. This is preferable.

As the coating method, for example, a method of applying the above-mentioned conductive paint on a substrate using a spin coating method, a spray coating method, an ink jet method, a dip method, a roll coating method, a screen printing method or the like is employed.
Since the conductive coating applied on the substrate contains a solvent, the substrate coated with the conductive coating is dried at room temperature in the atmosphere, or at a predetermined temperature, for example, 50 ° C. to 80 ° C. By drying at a temperature of 1, the solvent contained in the conductive paint is dissipated to form a coating film.
In addition, if there is little content of a solvent and there is no possibility that a film quality will change even if it irradiates with plasma and electromagnetic waves, a drying process can be skipped.

"Plasma irradiation"
The reaction gas is introduced into the coating film at atmospheric pressure to make the reaction gas into plasma, the plasma is irradiated to the coating film, and the coating film is modified to make it transparent on the substrate. A conductive film is formed.
In this case, the reactive gas is selected from the group consisting of nitrogen (N ₂ ), He, Ne, Ar, Kr, Xe and other rare gases, oxygen (O ₂ ), ozone (O ₃ ), and hydrogen (H ₂ ). One kind or two or more kinds of mixed gases are used.
This reaction gas may contain one or more organic metal compounds.

There are four types of plasma irradiation methods.
Here, each of the four types of plasma irradiation methods will be described together with a plasma irradiation apparatus used therefor.

(First plasma irradiation method)
A reactive gas is introduced onto the coating film under atmospheric pressure, this reactive gas is turned into plasma, this plasma is irradiated onto the coating film, and the coating film is modified to form a transparent conductive film on the substrate. It is a method of forming.
FIG. 1 is a cross-sectional view showing a plasma irradiation apparatus used in the first method. In the figure, 1 is a gas introduction pipe for introducing a reaction gas, and 2 is provided below the tip of the gas introduction pipe 1. The plasma generating electrode 3 is a plasma generating power source for generating plasma between the plasma generating electrodes 2 and 2.

In order to irradiate the coating film with plasma using this plasma irradiation apparatus, first, a film-coated substrate 8 in which a coating film 7 is formed on a substrate 6 such as a glass substrate is produced, and this film-coated substrate 8 is prepared. Is placed below the plasma generating electrodes 2 and 2 with the coating film 7 facing up.
Next, the reaction gas g is introduced between the plasma generating electrodes 2 and 2 through the gas introduction tube 1 and a high voltage is applied between the plasma generating electrodes 2 and 2 from the plasma generating power source 3 at atmospheric pressure. By generating an arc discharge, a plasma P is generated between the plasma generating electrodes 2 and 2, and active particles such as electrons, ions, radicals, excited atoms and molecules are emitted from the plasma P.

The reaction gas g contains at least one of nitrogen (N ₂ ), He, Ne, Ar, Kr, Xe and other rare gases, oxygen (O ₂ ), ozone (O ₃ ), and hydrogen (H ₂ ). Use gas. For example, a mixed gas of 90% N ₂ -10% O ₂ or the like.
Further, if an organometallic component is added to the reaction gas g, the sinterability of the film can be improved, which is effective in obtaining a high-quality film.
Here, the distance d between the plasma generating electrodes 2 and 2 and the film-coated substrate 8, the plasma output, and the plasma irradiation angle depend on the shape of the substrate 6 so that the plasma P is efficiently irradiated onto the coating film 7. Adjust θ appropriately.

  Here, the distance d between the plasma generating electrodes 2 and 2 and the coating film 7 was adjusted, and the optimum distance d was set to 1 to 50 mm. If the distance d is less than 1 mm, the plasma P becomes unstable and the substrate 6 is heated, which is not preferable. On the other hand, if the distance d exceeds 50 mm, the active energy of the plasma P is sufficiently imparted to the coating film 7. Because you can't.

  The plasma irradiation angle θ is an angle formed by the center line Ax between the plasma generating electrodes 2 and 2, that is, the central axis in the flow direction of the plasma P, and the surface of the coating film 7, that is, the irradiation surface of the plasma P. That is, it is set according to the shape of the substrate 6. The range of the plasma irradiation angle θ is 0.1 to 179.9 degrees, preferably 10 to 170 degrees. When the plasma irradiation angle θ is less than 0.1 degrees or exceeds 179.9 degrees, the active energy of the plasma P cannot be sufficiently applied to the coating film 7.

  When the coating film 7 contains an organic metal compound, a metal inorganic acid salt, a metal organic acid salt, etc. by irradiating the coating film 7 with the plasma P at a plasma irradiation angle θ, these react to react with the low resistance. In addition, a homogeneous transparent conductive film 9 having a high visible light transmittance can be obtained, and when metal oxide fine particles, metal / alloy fine particles, and the like are included, these fine particles are fused together to form a low resistance. And the transparent conductive film 9 with a high visible light transmittance can be obtained.

(Second plasma irradiation method)
When a reaction gas is introduced onto the coating film under atmospheric pressure and plasma is generated in the reaction gas, an electric field is generated between the electrode provided on the surface of the substrate opposite to the coating film side and the plasma. Is applied to the film while irradiating the film while controlling the flow of plasma and modifying the film to form a transparent conductive film on the substrate.

FIG. 2 is a cross-sectional view showing a plasma irradiation apparatus used in the second method. This plasma irradiation apparatus is different from the plasma irradiation apparatus shown in FIG. A back electrode 12 whose periphery is protected by a dielectric 11 such as glass is provided so as to be in close contact with the surface, and a bias voltage is applied between the back electrode 12 and the plasma P in contact with the surface of the coating film 7. Thus, an electric field is formed on the peripheral edge of the coating film 7, and the plasma P is rectified on the coating film 7 by this electric field.
As the bias voltage, any one of a DC voltage, a bipolar pulse voltage, an AC voltage, a high-frequency voltage, or a voltage obtained by effectively combining these voltages is suitable.

In this method, a DC voltage, a bipolar pulse voltage, an AC voltage, a high-frequency voltage, or a voltage obtained by effectively combining these is used between the back electrode 12 and the plasma P in contact with the surface of the coating film 7. By applying such a bias voltage, the coating film 7 is efficiently modified by the rectified plasma P, and a uniform transparent conductive film 9 having low resistance and high visible light transmittance can be obtained.
Here, the back electrode 12 protected by the dielectric 11 is used. However, when the adhesion between the back electrode 12 and the substrate 6 is ensured, only the back electrode 12 may be provided.

(Third plasma irradiation method)
When a reaction gas is introduced onto the coating film under atmospheric pressure and plasma is generated in the reaction gas, the substrate is tilted with respect to the direction of plasma irradiation, By applying a voltage between the electrode provided on the surface and the rectifying electrode provided opposite to the coating film, the coating film is irradiated while modifying the plasma flow to modify the coating film. By this, it is the method of forming a transparent conductive film on a base material.

FIG. 3 is a sectional view showing a plasma irradiation apparatus used in the third method. The plasma irradiation apparatus is different from the plasma irradiation apparatus shown in FIG. 2 in that the periphery is protected by a dielectric 11 such as glass. By tilting the back electrode 12 within the range where the plasma irradiation angle θ is in the range of 5 to 85 degrees, the coating film 7 of the film-coated substrate 8 in close contact with the back electrode 12 is tilted within the above angle range. Furthermore, a rectifying electrode 21 is provided opposite to the coating film 7, and an electric field is formed in the upper region of the coating film 7 by applying a bias voltage between the back electrode 12 and the rectifying electrode 21. This is the point that the plasma P is rectified along the coating film 7 by this electric field.
As the bias voltage, any one of a DC voltage, a bipolar pulse voltage, an AC voltage, a high-frequency voltage, or a voltage obtained by effectively combining these voltages is suitable.

In this method, a bias voltage composed of a DC voltage, a bipolar pulse voltage, an AC voltage, a high-frequency voltage, or a voltage obtained by effectively combining these is applied between the back electrode 12 and the rectifying electrode 21. As a result, the plasma P rectified along the coating film 7 is reactivated to generate a more uniform plasma P ′, and the coating film 7 is efficiently modified by the plasma P ′. Therefore, by using plasma P ′ having a high modification efficiency, a homogeneous transparent conductive film 9 having a low resistance and a high visible light transmittance can be obtained.
Here, the back electrode 12 protected by the dielectric 11 is used. However, when the adhesion between the back electrode 12 and the substrate 6 is ensured, only the back electrode 12 may be provided.

(Fourth plasma irradiation method)
When a reaction gas is introduced onto the coating film under atmospheric pressure and plasma is generated in the reaction gas, the substrate is moved with respect to the direction of plasma irradiation, and the side opposite to the coating film side of the substrate. By applying a voltage between the electrode provided on the surface of the electrode and the rectifying electrode provided opposite to the coating film, the coating film is irradiated while controlling the plasma flow, and this coating film is modified. This is a method for forming a transparent conductive film on a substrate.

  FIG. 4 is a sectional view showing a plasma irradiation apparatus used in the fourth method. This plasma irradiation apparatus is different from the plasma irradiation apparatus shown in FIG. 1 in that a plastic film 31 is used instead of the film-coated substrate 8. A film-like film 32 on which a coating film 7 is formed is used, and the film-like film 32 is disposed under the plasma generating electrodes 2 and 2 and the surface is covered with a dielectric 33 such as glass. The coating film 7 is wound outwardly on the electrode 34, and a rectifying electrode 21 is provided opposite to the coating film 7, and a bias voltage is applied between the rectifying electrode 21 and the roll-shaped back electrode 34. By doing so, an electric field is formed in the upper region of the rotating coating film 7, and the plasma P is rectified along the coating film 7 by this electric field.

As the bias voltage, any one of a DC voltage, a bipolar pulse voltage, an AC voltage, a high-frequency voltage, or a voltage obtained by effectively combining these voltages is suitable. Further, when the rectifying action of the plasma P is not particularly required, the rectifying electrode 21 may be omitted.
Further, as shown in FIG. 5, the rectifying electrode 21 is directly connected to the ground (FIG. 5 (a)) via a coil (inductance) 37 (FIG. 5 (b)) and connected in parallel as necessary. Any appropriate grounding method (grounding (c)) can be selected via the capacitor (capacitance) 38 and the resistor 39.

In this method, a bias voltage composed of a DC voltage, a bipolar pulse voltage, an AC voltage, a high-frequency voltage, or a voltage obtained by effectively combining these is provided between the rectifying electrode 21 and the roll-shaped back electrode 34. By applying, the plasma P rectified along the coating film 7 is reactivated and more uniform plasma P ′ is generated, and the coating film 7 is efficiently modified by the plasma P ′. Therefore, by using plasma P ′ having a high modification efficiency, a homogeneous transparent conductive film 9 having a low resistance and a high visible light transmittance can be obtained.
Moreover, since the film-coated film 32 in which the coating film 7 is formed on the plastic film 31 is used, the film-coated film 32 having the homogeneous transparent conductive film 9 having low resistance and high visible light transmittance can be obtained.

According to the present invention, by irradiating the coating film 7 with uniform plasma P ′, oxidation and sintering of the coating film 7 can proceed simultaneously under atmospheric pressure without using a heating device.
At this time, the organic metal compound, metal inorganic acid salt, metal organic acid salt, metal / alloy fine particles, etc. contained in the coating film 7 are oxidized and densely sintered, resulting in low resistance and high visible light transmission. Rate transparent conductive film can be produced.

EXAMPLES Hereinafter, although this invention is demonstrated concretely by Examples 1-4, this invention is not limited by these Examples.
[Example 1]
In-Sn alloy powder obtained by reducing tin-added indium oxide (ITO) fine particles (primary particle size: 100 nm or less) containing 5% Sn with a mixed gas of 97% N ₂ -3% H ₂ at 600 ° C. Got. Next, this In—Sn alloy powder was dispersed in n-butyl acetate so as to have a concentration of 5% by weight to prepare a conductive paint.

This conductive paint was applied on a glass substrate by spin coating to form a coating film having a film thickness of about 300 nm. The obtained coating film was irradiated with plasma with an output of 100 W / cm ² under atmospheric pressure using a plasma irradiation apparatus shown in FIG. 1 without using a heating device, thereby modifying the coating film.
Here, the distance d between the plasma generating electrodes 2 and 2 and the film-coated substrate 8 is 15 mm, the plasma irradiation angle θ is 90 degrees, and a mixed gas of 90% N ₂ -10% O ₂ is used as a reactive gas. .

Here, the plasma irradiation time is set to 3 minutes, 5 minutes, 10 minutes, and 15 minutes, and surface resistance (sheet resistance Ω / □) and visible light transmittance (%) with respect to the obtained transparent conductive film. Was measured.
The measuring method is as follows.
Surface resistance (sheet resistance Ω / □): measured with Loresta (Mitsubishi Chemical Corporation) Visible light transmittance: manufactured by Nippon Denshoku Co., Ltd. according to Japanese Industrial Standard “JIS K 7105”
Measure with haze meter

The measurement results are shown in Table 1.
The obtained transparent conductive film was sufficiently dense and the surface resistance was small. It was also found that the visible light transmittance was good.

[Example 2]
Tin-doped indium oxide (ITO) fine particles (primary particle diameter: 100 nm or less) containing 5% Sn were dispersed in n-butyl acetate so as to have a concentration of 5% by weight to prepare a conductive paint.
This conductive paint was applied on a glass substrate by spin coating to form a coating film having a film thickness of about 300 nm. The resulting coating film was irradiated with plasma with an output of 100 W / cm ² under atmospheric pressure using a plasma irradiation apparatus shown in FIG. 2 without using a heating device, thereby modifying the coating film.
Here, the distance d between the plasma generating electrodes 2 and 2 and the film-coated substrate 8 is 15 mm, the plasma irradiation angle θ is 90 degrees, and a mixed gas of 90% N ₂ -10% O ₂ is used as a reactive gas. .

Here, the plasma irradiation time was set to 3 minutes, 1 minute, 3 minutes, and 5 minutes. For the obtained transparent conductive film, the surface resistance (sheet resistance Ω / □) according to Example 1, Visible light transmittance (%) was measured. The measurement results are shown in Table 2.
The obtained transparent conductive film was sufficiently dense and the surface resistance was small. It was also found that the visible light transmittance was good.

[Example 3]
2 g of indium nitrate trihydrate (In (NO ₃ ) ₃ .3H ₂ O) and 0.16 g of tin (IV) chloride pentahydrate (SnCl ₄ .5H ₂ O) were dissolved in 2 g of acetylacetone, Further, 5 g of acetone was added, and then the mixture was stirred for 24 hours at room temperature (25 ° C.) using a magnetic stirrer to prepare a conductive paint.

This conductive paint was applied on a glass substrate by a spin coating method to form a coating film. The resulting coating film was irradiated with plasma with an output of 100 W / cm ² under atmospheric pressure using a plasma irradiation apparatus shown in FIG. 2 without using a heating device, thereby modifying the coating film.
Here, the distance d between the plasma generating electrodes 2 and 2 and the film-coated substrate 8 is 15 mm, the plasma irradiation angle θ is 90 degrees, and a mixed gas of 90% N ₂ -10% O ₂ is used as a reactive gas. . The plasma irradiation time was set to 3 minutes.

The formation of the coating film and the plasma irradiation were repeated 5 times in total to produce a transparent conductive film having a film thickness of about 300 nm.
With respect to the obtained transparent conductive film, the surface resistance (sheet resistance Ω / □) and the visible light transmittance (%) were measured according to Example 1. Table 3 shows the measurement results.
The obtained transparent conductive film was sufficiently dense and the surface resistance was small. It was also found that the visible light transmittance was good.

[Example 4]
Tin-doped indium oxide (ITO) fine particles (primary particle diameter: 100 nm or less) containing 5% Sn were dispersed in n-butyl acetate so as to have a concentration of 5% by weight to prepare a conductive paint.
This conductive paint was applied on a glass substrate by a spin coat method to form a coating film having a thickness of about 250 nm. The obtained coating film was irradiated with plasma with an output of 100 W / cm ² under atmospheric pressure using a plasma irradiation apparatus shown in FIG. Got.

Here, the distance d between the plasma generating electrodes 2 and 2 and the film-coated substrate 8 was 15 mm, the plasma irradiation angle θ was 90 degrees, and the plasma irradiation time was 10 minutes. As a reaction gas, a mixed solution of trimethylindium (In (CH ₃ ) ₃ ) and tetraethyltin (Sn (C ₂ H ₅ ) ₄ ) is heated to 80 ° C., and 90% N ₂ − A gas bubbled with a mixed gas of 10% O ₂ was used.
The film thickness of the obtained transparent conductive film was about 300 nm.

With respect to this transparent conductive film, surface resistance (sheet resistance Ω / □) and visible light transmittance (%) were measured according to Example 1. Table 4 shows the measurement results.
The obtained transparent conductive film was sufficiently dense and the surface resistance was small. It was also found that the visible light transmittance was good.

[Comparative example]
Tin-doped indium oxide (ITO) fine particles (primary particle diameter: 100 nm or less) containing 5% Sn were dispersed in n-butyl acetate so as to have a concentration of 5% by weight to prepare a conductive paint.
This conductive paint was applied on a glass substrate by spin coating to form a coating film having a film thickness of about 300 nm.

Subsequently, this coating film was baked for 30 minutes under atmospheric pressure and the maximum holding temperature using the heating apparatus, and the transparent conductive film was obtained.
Here, the maximum holding temperature was set to two types of 400 ° C. and 500 ° C.
With respect to the obtained transparent conductive film, the surface resistance (sheet resistance Ω / □) and the visible light transmittance (%) were measured according to Example 1. Table 5 shows the measurement results.

According to the above measurement result, it turned out that the transparent conductive film of Examples 1-4 has a small surface resistance (sheet resistance) compared with the transparent conductive film of a comparative example, and high visible light transmittance | permeability.
In addition, even when any one of an organometallic compound, a metal inorganic salt, and a metal organic salt was added to each coating solution of Examples 1 to 4, the obtained coating film was subjected to plasma under atmospheric pressure and in an oxidizing atmosphere. Alternatively, it was confirmed that a transparent conductive film having a low resistance and a high visible light transmittance can be formed by irradiating electromagnetic waves such as laser and ultraviolet rays.

  The method for forming a transparent conductive film of the present invention forms a transparent conductive film with low resistance and high visible light transmittance by irradiating plasma on a coating film formed on a substrate to modify the coating film. Therefore, it can be applied to various display devices such as a plasma display (PD), a liquid crystal display (LCD), an electroluminescent display (EL), a cathode ray tube (CRT), and a projection (PJTV). Needless to say, the effect is also great in various industrial fields such as windows for automobiles and buildings.

It is sectional drawing which shows the plasma irradiation apparatus used with the 1st plasma irradiation method of this invention. It is sectional drawing which shows the plasma irradiation apparatus used with the 2nd plasma irradiation method of this invention. It is sectional drawing which shows the plasma irradiation apparatus used with the 3rd plasma irradiation method of this invention. It is sectional drawing which shows the plasma irradiation apparatus used with the 4th plasma irradiation method of this invention. It is a circuit diagram which shows the grounding method of the rectification electrode of the plasma irradiation apparatus used with the 4th plasma irradiation method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas introduction tube 2 Electrode for plasma generation 3 Power supply for plasma generation 6 Base material 7 Coating film 8 Base material with film 9 Transparent conductive film 11 Dielectric 12 Rear electrode 21 Electrode for rectification 31 Plastic film 32 Film with film 33 Dielectric 34 Rolled back electrode 37 Coil 38 Capacitor 39 Resistance g Reaction gas P Plasma

Claims (11)

  A conductive paint is applied on a substrate to form a coating film, and a reactive gas is introduced onto the coating film at atmospheric pressure to make the reactive gas into plasma, and this plasma is irradiated onto the coating film. And forming the transparent conductive film on the substrate by modifying the coating film.   The method for forming a transparent conductive film according to claim 1, wherein the reaction gas includes one or more selected from the group of nitrogen, rare gas, oxygen, ozone, and hydrogen.   The method for forming a transparent conductive film according to claim 1, wherein the reaction gas contains one or more organic metal compounds.   Controlling the flow of plasma irradiated to the coating film by applying a voltage between the electrode provided on the surface opposite to the coating film side of the substrate and the plasma generating electrode for generating the plasma The method for forming a transparent conductive film according to claim 1, 2, or 3.   The substrate is inclined with respect to the plasma irradiation direction, and between the electrode provided on the surface opposite to the coating film side of the substrate and the rectifying electrode provided facing the coating film. 4. The method of forming a transparent conductive film according to claim 1, wherein a flow of plasma applied to the coating film is controlled by applying a voltage.   While moving the substrate with respect to the plasma irradiation direction, between the electrode provided on the surface of the substrate opposite to the coating film side and the rectifying electrode provided facing the coating film The method of forming a transparent conductive film according to claim 1, 2 or 3, wherein a flow of plasma applied to the coating film is controlled by applying a voltage to the coating film.   The method of forming a transparent conductive film according to claim 6, wherein the movement is a rotational movement around an axis orthogonal to the direction of plasma irradiation.   The transparent conductive film according to any one of claims 4 to 7, wherein the voltage is one or more selected from the group consisting of a DC voltage, an AC voltage, a high-frequency voltage, and a bipolar pulse voltage. Forming method.   The method for forming a transparent conductive film according to claim 1, wherein the substrate is made of glass or an organic polymer compound.   10. The conductive paint according to claim 1, wherein the conductive paint includes any one of an organic metal compound, a metal inorganic acid salt, a metal organic acid salt, a metal oxide fine particle, and a fine particle composed of a metal or an alloy. The formation method of the transparent conductive film of claim | item.   A transparent conductive film formed by the method for forming a transparent conductive film according to claim 1.

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