JP2001325832A - Transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film, having a less light scattering property with a transparent conductive layer of low electrical resistance. SOLUTION: The transparent conductive film has the transparent conductive layer on at least a face of one side of a transparent support. The transparent support has a haze degree of 0.1-13%, and the transparent conductive layer is a compressed layer of conductive fine particles having a primary particle size of 50 nm or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film, and more particularly to a transparent conductive film having high transparency and low electric resistance. The transparent conductive film of the present invention can be used as a transparent electrode such as an electroluminescence panel electrode, an electrochromic device electrode, a liquid crystal electrode, a transparent surface heating element, and a touch panel, and can also be used as a transparent electromagnetic wave shielding film. .

[0002]

2. Description of the Related Art At present, a transparent conductive layer constituting a transparent conductive film is mainly produced by a sputtering method. There are various methods of spattling, for example,
In this method, inert gas ions generated by direct current or high-frequency discharge in a vacuum are caused to collide with the target surface at an accelerated rate, and atoms constituting the target are knocked out from the surface and deposited on the support surface to form a transparent conductive layer.

[0003] The sputtering method is excellent in that a transparent conductive layer having a low surface electric resistance can be formed even with a relatively large area. However, there is a disadvantage that the apparatus is large and the film forming speed is low. As the area of the transparent conductive film is further increased in the future, the size of the apparatus will be further increased. This technically causes problems such as the necessity of increasing control accuracy, and another problem arises that manufacturing costs increase. Further, the number of targets is increased to compensate for the low film formation speed, and the speed is increased. However, this also causes a problem in that the size of the apparatus is increased.

[0004] Production of a transparent conductive film by a coating method has also been attempted. In a conventional coating method, a conductive paint in which conductive fine particles are dispersed in a binder solution is applied on a resin film, dried, and cured to form a transparent conductive layer. The coating method has the advantages that a large-area transparent conductive layer can be easily formed, the apparatus is simple and the productivity is high, and a transparent conductive film can be manufactured at a lower cost than the sputtering method. In the transparent conductive layer formed by the coating method, the conductive fine particles come into contact with each other to form an electrical path, thereby exhibiting conductivity. However, the transparent conductive layer produced by the conventional coating method has a drawback that the contact of the conductive fine particles is insufficient due to the presence of the binder, and the obtained transparent conductive layer has a high electric resistance (poor conductivity). However, its use is limited.

[0005] As the production of a conductive layer by a conventional coating method,
For example, Japanese Patent Application Laid-Open No. 9-109259 discloses a first step of applying a coating composed of a conductive powder and a binder resin on a transfer plastic film and drying the coating to form a conductive layer. Pressurization (5-100kg / cm
² ), a second step of heating (70 to 180 ° C.) and a third step of laminating this conductive layer on a plastic film or sheet and thermocompression bonding are disclosed.

In this method, a large amount of binder resin is used (in the case of an inorganic conductive powder, binder 1 is used).
100 parts by weight, 100 to 500 parts by weight of conductive powder, and in the case of organic conductive powder, 0.1 to 30 parts by weight of conductive powder with respect to 100 parts by weight of binder)
A conductive layer having a low electric resistance cannot be obtained.

Further, for example, Japanese Patent Application Laid-Open No. Hei 8-199096 discloses a binder-free conductive film comprising tin-doped indium oxide (ITO) powder, a solvent, a coupling agent, a metal organic acid salt or an inorganic acid salt. A method is disclosed in which a forming paint is applied to a glass plate and fired at a temperature of 300 ° C. or higher. In this method, since no binder is used, the electric resistance of the conductive film is reduced. But 3
Since it is necessary to perform the firing step at a temperature of 00 ° C. or higher,
It is difficult to form a conductive film on a support such as a resin film. That is, the resin film is melted, carbonized, or burned by the high temperature. Depending on the type of resin film, for example, a polyethylene terephthalate (PET) film may have a limit of 130 ° C.

[0008] As the conductive layer formed by a method other than the coating method,
Japanese Patent Application Laid-Open No. Hei 6-13785 discloses a powder compression layer in which at least a part, preferably all of the voids of a skeleton structure composed of a conductive substance (metal or alloy) powder is filled with a resin, A conductive film comprising a lower resin layer is disclosed. The production method will be described by taking a case where a film is formed on a plate material as an example. According to the publication, first, a resin, a powdery substance (metal or alloy) and a plate material to be processed are vibrated or agitated in a container together with a film forming medium (steel balls having a diameter of several mm). A resin layer is formed on the surface. Subsequently, the powder material is captured and fixed to the resin layer by the adhesive force of the resin layer. In addition, the vibrating or agitating film-forming medium exerts a striking force on the vibrating or agitating powder material to form a powder compaction layer. However, a considerable amount of resin is required to obtain the effect of fixing the powder compression layer. Further, the production method is more complicated than the coating method.

As another conductive layer formed by a method other than the coating method, JP-A-9-107195 discloses a method in which a conductive short fiber is sprinkled on a film such as PVC and deposited, followed by pressure treatment. Also disclosed is a conductive fiber-resin integrated layer. The conductive short fiber is a short fiber such as polyethylene terephthalate, which is coated with nickel plating or the like. However, the pressing operation is preferably performed under a temperature condition at which the resin matrix layer exhibits thermoplasticity.
Since high temperature and low pressure conditions of 75 ° C. and 20 kg / cm ² are required, it is difficult to form a conductive film on a support such as a resin film.

[0010]

From such a background,
It is desired to develop a transparent conductive film which includes a transparent conductive layer having a low electric resistance value, is easy to manufacture, has high productivity, and can be manufactured at low cost. Therefore, an object of the present invention is to provide a transparent conductive film having a low light scattering and having a transparent conductive layer having a low electric resistance value.

[0011]

Means for Solving the Problems Conventionally, in a coating method,
It was thought that a transparent conductive film could not be formed unless a large amount of binder resin was used, or a conductive film could not be obtained unless a conductive material was sintered at a high temperature when no binder resin was used. . However, as a result of intensive studies by the present inventors, surprisingly, without using a binder, and without firing at a high temperature, there is mechanical strength by compression, and the electric resistance value is low and light scattering is low. The inventors have found that a transparent conductive layer can be obtained, and have reached the present invention.

According to the present invention, there is provided a transparent support, and a transparent conductive film having a transparent conductive layer on at least one surface of the transparent support, wherein the transparent support has a haze of 0.1 to 0.1.
13%, and the transparent conductive layer has a primary particle size of 5%.
The structure was such that it was a compressed layer of conductive fine particles of 0 nm or less.

Further, the present invention is configured such that the transparent support is a resin film. Further, the present invention is configured such that the haze degree of the transparent conductive film is 15% or less. Further, the present invention is configured such that the transparent conductive layer is formed by compressing the conductive fine particles with a compressive force of 44 N / mm ² or more.

In the present invention, since the conductive fine particles are compressed in the transparent conductive layer, the conductive fine particles are sufficiently contacted with each other, the electric resistance of the transparent conductive layer is low, and The strength and the adhesion to the transparent support become large.

[0015]

Next, an embodiment of the present invention will be described. The transparent conductive film of the present invention is a transparent conductive film provided with a transparent conductive layer on at least one surface of the transparent support, and has a haze degree of 0.1 to 1 for the transparent support.
The range is 3%, and the transparent conductive layer is a compressed layer of conductive fine particles having a primary particle size of 50 nm or less.

Here, in the present invention, “transparent” means that visible light is transmitted. Regarding the degree of light scattering, the required level varies depending on the use of the transparent conductive film. In the present invention, those having scattering which is generally called translucent are also included.

As the transparent support, various materials such as resin film, glass, ceramics and the like can be used.
Those having a haze of 0.1 to 13%, preferably 0.1 to 5% can be used. If the haze of the transparent support exceeds 13%, the haze of the transparent conductive film on which the transparent conductive layer is formed exceeds 15%, and the electroluminescent panel electrode, the electrochromic device electrode, the liquid crystal electrode, and the heat generation on the transparent surface. The use as a transparent electrode such as a body or a touch panel may be hindered.

When a material having no flexibility, such as glass or ceramics, is used as the transparent support, there is a high possibility that the transparent support will be broken at the time of compression in a subsequent step, so that it is necessary to consider this point. Therefore, as the transparent support, a resin film that does not break even when the compression force in the compression step is increased is preferable. As described below, the resin film is preferable in that it has good adhesion to the transparent conductive layer, which is a compressed layer of the conductive fine particles, and is also suitable for applications in which weight reduction is required. In the present invention, a resin film can be used as a transparent support because there is no pressurizing step at a high temperature or a baking step.

Examples of the resin film include a polyester film such as polyethylene terephthalate (PET), a polyolefin film such as polyethylene and polypropylene, a polycarbonate film, an acrylic film, a norbornene film (Arton, manufactured by JSR Corporation), and the like.

In a resin film such as a PET film, conductive fine particles are applied during the compression step after coating and drying.
Part of the conductive fine particles in contact with the ET film is PE
It feels like it is embedded in the T film, and the conductive fine particle layer adheres well to the PET film. In the case of a hard material such as glass or a resin film having a hard film surface, the adhesion between the fine particle layer and the support may be insufficient because the conductive fine particles are not embedded. In that case, a soft resin layer is formed in advance on a glass surface or a hard film surface, and conductive fine particles are applied, dried,
It is preferable to compress. After the compression, the soft resin layer may be cured by heat, ultraviolet light, or the like. The soft resin layer is preferably a substance that does not dissolve in the liquid in which the conductive fine particles are dispersed. When dissolved, the solution containing the resin comes around the conductive fine particles due to capillary action, and as a result, the electrical resistance value of the obtained transparent conductive layer increases.

The conductive fine particles constituting the transparent conductive layer are not particularly limited as long as they do not impair the transparency of the transparent conductive film, and any of inorganic conductive fine particles and organic conductive fine particles can be used. be able to. Examples of the inorganic conductive fine particles include tin oxide, indium oxide, zinc oxide, and cadmium oxide. Antimony-doped tin oxide (ATO) and fluorine-doped tin oxide (FT)
Fine particles such as O), tin-doped indium oxide (ITO), and aluminum-doped zinc oxide (AZO) are preferred. Further, ITO is preferable in that more excellent conductivity can be obtained.
Alternatively, a material in which an inorganic material such as ATO or ITO is coated on the surface of transparent fine particles such as barium sulfate can be used.

The primary particle size of these conductive fine particles is 50
nm or less, preferably in the range of 5 nm to 50 nm.
If the primary particle size of the conductive fine particles exceeds 50 nm, light scattering of the transparent conductive layer increases, which is not preferable. Generally, it is said that the Mie scattering equation is satisfied in a region where the primary particle size is almost the same as the wavelength of light. Further, when the primary particle size is smaller than the scattering wavelength, it is described by the Rayleigh equation. Since Rayleigh's equation states that the total scattering power is proportional to the sixth power of the particle size, the scattering decreases rapidly as the particle size decreases. Therefore, by using the conductive fine particles having a small primary particle size, a transparent conductive layer with low light scattering and low haze can be obtained. And even if such a transparent conductive layer is formed on a transparent support having a haze of 13%, the haze of the transparent conductive film can be reduced to 15% or less.

The thickness of the transparent conductive layer, which is a compressed layer of the conductive fine particles as described above, can be in the range of 0.1 to 5 μm, preferably 0.2 to 2 μm. The surface electric resistance of the transparent conductive layer can be appropriately set according to the use of the transparent conductive film.

In the present invention, the transparent conductive layer constituting the transparent conductive film may contain a small amount of resin within a range that does not increase the electric resistance value. For example, when the volume of the conductive fine particles is 100, the transparent conductive layer can contain a resin in a volume of less than 25, preferably less than 20, but more preferably the transparent conductive layer in the later-described compression. Not contain resin. The resin has an effect of reducing the light scattering of the transparent conductive layer, but on the other hand, increases the electric resistance of the transparent conductive layer. The reason is that the contact between the conductive fine particles is hindered by the insulating resin, and when the amount of the resin is large, the fine particles do not contact each other, so that the electron transfer between the fine particles is hindered. Therefore, when the resin is contained in consideration of both improvement of haze and securing of conductivity between the conductive fine particles, the resin is used within the above-mentioned volume range. If the amount of the resin is within this range, by increasing the compression pressure in the compression step as described later, the electric resistance becomes substantially equal to the electric resistance of the transparent conductive layer when no resin is contained. This is considered to be because the conductive fine particles come into contact with each other as the compression pressure is increased. In this case, since the amount of the resin is small, it is considered that almost all of the voids of the conductive fine particles exist in the compressed layer of the conductive fine particles.

The above-mentioned resin is not particularly limited, and a thermoplastic resin having excellent transparency or a polymer having rubber elasticity can be used alone or in combination of two or more. Examples of the resin include a fluoropolymer,
Silicone resin, acrylic resin, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, polyethylene,
Examples include polypropylene, SBR, polybutadiene, and polyethylene oxide.

Examples of the fluorine-based polymer include polytetrafluoroethylene, polyvinylidene fluoride (PVDF),
Examples thereof include vinylidene fluoride-ethylene trifluoride copolymer, ethylene-tetrafluoroethylene copolymer, and propylene-tetrafluoroethylene copolymer. Further, a fluorine-containing polymer in which hydrogen in the main chain is substituted with an alkyl group can also be used. The higher the density of the resin, the smaller the volume, even if a larger weight is used, and it is easy to satisfy the above volume condition.

The volume of the conductive fine particles and the volume of the resin are not apparent volumes but true volumes. The true volume is obtained by obtaining the density using an instrument such as a pycnometer based on JIS Z 8807, and dividing the weight of the material used by the density. In this way, the amount of the resin used is defined not by weight but by volume, in the transparent conductive layer obtained after compression, how the resin is present with respect to the conductive fine particles, when considering, It reflects the reality more. In the present invention, it is of course possible to form a transparent conductive film having a transparent conductive layer on both surfaces of a transparent support.

Next, an example of the method for producing the transparent conductive film of the present invention will be described. The transparent conductive layer constituting the transparent conductive film is formed by applying a dispersion containing conductive fine particles and, if necessary, a trace amount of resin as a conductive paint on a transparent support, drying, and then compressing. it can.

The liquid in which the conductive fine particles are dispersed is not particularly limited as long as the resin is dissolved in the conductive paint, and various known solvents can be used. . For example, as a solvent, saturated hydrocarbons such as hexane, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone , Ethyl acetate, esters such as butyl acetate,
Ethers such as tetrahydrofuran, dioxane and diethyl ether; amides such as N, N-dimethylformamide, N-methylpyrrolidone (NMP) and N, N-dimethylacetamide; and halogenated hydrocarbons such as ethylene chloride and chlorobenzene. Can be mentioned. Among these, polar solvents are preferable, and alcohols such as methanol and ethanol, and amides such as NMP are preferable. These solvents may be used alone or in combination of two or more. Further, a dispersant may be used to improve the dispersibility of the conductive fine particles.

Further, water can be used as a solvent.
When water is used, the transparent support needs to be hydrophilic. Since the resin film is usually hydrophobic, it easily repels water, and it is difficult to obtain a uniform film. When the transparent support is a resin film, it is necessary to mix alcohol with water or to make the surface of the support hydrophilic.
When a resin is contained, it is better to consider the solubility of the resin.

The amount of the solvent to be used is not particularly limited as long as the dispersion of the conductive fine particles has a viscosity suitable for coating. For example, the liquid is about 100 to 100,000 parts by weight with respect to 100 parts by weight of the conductive fine particles. It may be appropriately selected according to the types of the conductive fine particles and the liquid.

The dispersion of the conductive fine particles in the liquid may be performed by a known dispersion method. For example, the particles are dispersed by a sand grinder mill method. At the time of dispersion, it is also preferable to use a medium such as zirconia beads in order to loosen aggregation of the conductive fine particles. At the time of dispersion, care should be taken not to mix impurities such as dust.

Various additives may be added to the dispersion of the conductive fine particles as long as the conductivity is not reduced. For example, additives such as an ultraviolet absorber, a surfactant, and a dispersant.

The application of the dispersion liquid of the conductive fine particles on the transparent support can be performed by a known method without any particular limitation. For example, it can be performed by a coating method such as a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion nozzle method, a curtain method, a gravure roll method, a bar coat method, a dip method, a kiss coat method, and a squeeze method. Further, the dispersion liquid can be attached to the transparent support by spraying or spraying.

The drying temperature depends on the type of liquid used for dispersion, but is preferably about 10 to 150 ° C. If the temperature is lower than 10 ° C., dew condensation of moisture in the air tends to occur, and if the temperature exceeds 150 ° C., the resin film support is deformed. At the time of drying, care should be taken so that impurities do not adhere to the surface of the conductive fine particles. The thickness of the conductive fine particle-containing layer after application and drying depends on the compression conditions and the use of the transparent conductive film in the next step,
It may be about 0.1 to 10 μm.

As described above, when the conductive fine particles are dispersed in a liquid, applied, and dried, a uniform film is easily formed. When a dispersion of conductive fine particles is applied and dried, even if a large amount of binder resin does not exist in the dispersion as in the related art,
That is, does not contain a resin as in the present invention, or
Even if the amount of the resin is a small amount equal to or less than a specific amount, the fine particles form a film. Although the reason why a film is formed even when a large amount of binder resin does not exist is not necessarily clear, fine particles gather due to capillary force when the liquid is dried and the amount of liquid decreases. Furthermore, the fact that the particles are fine particles has a large specific surface area and a strong cohesive force, so it is thought that they may become a film. However, the strength of the film at this stage is weak. Further, the transparent conductive layer has a high electric resistance value and a large variation in electric resistance value.

Next, the formed layer containing conductive fine particles is compressed to obtain a compressed layer of conductive fine particles. The compression reduces the electrical resistance and improves the strength of the film. That is, the compression increases the number of contact points between the conductive fine particles and the number of contact surfaces. Therefore, the electric resistance decreases and the strength of the coating increases. Since the fine particles originally have a property of easily aggregating, they become a strong film by being compressed. In addition, the compression reduces the haze.

Compression is 44 N / mm^Two Perform with the above compression force
Is preferred. 44N / mm^TwoIf the pressure is less than
The conductive particle-containing layer cannot be sufficiently compressed, and
It is difficult to obtain a transparent conductive layer having excellent electrical conductivity. 180 compression
N / mm^TwoThe above compression force is more preferable. High compression force
As a result, a transparent conductive layer having more excellent conductivity is obtained, and
The strength of the transparent conductive layer is improved, and the adhesion to the transparent support is strong.
Become solid. The higher the compression force, the higher the pressure resistance of the device
In general, 1000 N / mm ^TwoFor up to
Compression force is appropriate. In addition, compress at normal temperature (15-40
C.). Pressure under heating conditions
When compression (hot pressing) is performed and the compression pressure is increased
The resin film may be stretched.

The compression means is not particularly limited and can be performed by a sheet press, a roll press or the like, but is preferably performed by using a roll press machine. The roll press is a method of sandwiching a film to be compressed between rolls, compressing the roll, and rotating the roll. The roll press is preferably applied with a high pressure uniformly, and can be produced in a roll-to-roll manner, so that productivity is increased.

The roll temperature of the roll press is preferably normal temperature. In a heated atmosphere or in a compression (hot press) in which a roll is heated, when the compression pressure is increased, a problem such as the resin film being elongated occurs. When the compression pressure is reduced to prevent the resin film from stretching under heating,
The mechanical strength of the transparent conductive layer decreases, and the electrical resistance increases. If there is a reason to reduce the adhesion of moisture on the surface of the fine particles as much as possible, a heated atmosphere may be used to reduce the relative humidity of the atmosphere, but the temperature range is within the range where the film does not easily stretch. It is. Generally, the temperature is lower than the glass transition temperature (secondary transition temperature). The temperature may be set slightly higher than the temperature at which the required humidity is obtained in consideration of fluctuations in humidity. It is also preferable to adjust the temperature so that the roll temperature does not rise due to heat generation when continuously compressed by a roll press. The glass transition temperature of the resin film is determined by measuring dynamic viscoelasticity and refers to a temperature at which the mechanical loss of the main dispersion reaches a peak. For example, for a PET film, its glass transition temperature is around 110 ° C.

The roll of the roll press machine is preferably a metal roll because a strong pressure is applied. In addition, if the roll surface is soft, the conductive fine particles may be transferred to the roll during compression. Therefore, it is preferable to treat the roll surface with a hard film.

By forming the compressed layer of the conductive fine particles in this manner, the transparent conductive film of the present invention having the transparent conductive layer can be obtained. Further, in order to obtain a transparent conductive layer having a thickness of about 10 μm, a series of operations of coating, drying, and compressing a dispersion of conductive fine particles may be repeatedly performed.
The transparent conductive film of the present invention thus obtained has a transparent conductive layer exhibiting excellent conductivity, and a film sufficient for practical use despite being prepared without using a large amount of binder resin as in the related art. It has strength and excellent adhesion to a transparent support.

[0043]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

Example 1 First, the primary particle size was 10 to 30.
To 100 parts by weight of ATO fine particles (density: 6.6 g / cm ³ , manufactured by Ishihara Sangyo Co., Ltd.), 300 parts by weight of ethanol was added, and the medium was dispersed as zirconia beads by a disperser to prepare a conductive paint. . The particle size of the ATO fine particles was measured at a magnification of 400,000 times using a scanning electron microscope (SEM).

Next, the following six types of PET films (PE
The above conductive coating liquid was applied on T films A to F) using a bar coater and dried (60 ° C.). The resulting film is hereinafter referred to as the pre-compression ATO film. The thickness of the ATO-containing coating film was 1.7 μm. PET film A: Haze degree 1%, thickness 50 μm PET film B: Haze degree 5%, thickness 50 μm PET film C: Haze degree 10%, thickness 50 μm PET film D: Haze degree 13%, thickness 50 μm PET film E: Haze degree 20%, thickness 50 μm PET film F: Haze degree 42%, thickness 50 μm

Next, the pre-compression ATO film is sandwiched between metal rolls (having a roll surface subjected to hard chromium plating), and is placed at room temperature (23 ° C.) at a temperature of 34 ° C. per unit area.
The paper was compressed at 7 N / mm ² , and the roll was rotated to compress at a feed speed of 5 m / min. By compressing the ATO film in this way, a transparent conductive film provided with a transparent conductive layer (samples 1 to 6) was obtained. The thickness of the transparent conductive layer after compression was 1.0 μm.

With respect to the six kinds of transparent conductive films (samples 1 to 6) produced as described above, the haze degree and the electric resistance were measured according to the following measuring methods. The results are shown in Table 1 below. In addition, in order to evaluate the adhesion between the PET film and the transparent conductive layer and the strength of the transparent conductive layer, a 90 ° peel test was performed by the following method.
It was shown to.

Measurement of Haze Degree Haze meter (TC-H3DP manufactured by Tokyo Denshoku Co., Ltd.)
K type).

Measurement of Electric Resistance The transparent conductive film on which the transparent conductive layer was formed
Cut into a size of × 50mm, diagonal corner 2
Put a tester on the point and measure.

A 90 ° peel test A double-sided tape was attached to the surface of the PET film of the transparent conductive film opposite to the surface on which the transparent conductive layer was formed, and this was cut out to a size of 25 mm × 100 mm to obtain a test sample. Paste on the board. Then, apply cellophane tape to both ends (25 mm long side) of the test sample so that the test sample does not peel off. Thereafter, a cellophane tape (width 12 mm, No. 29 manufactured by Nitto Denko Corporation) is attached to the transparent conductive layer surface of the test sample so as to be parallel to the long side of the test sample. The sticking length between the cellophane tape and the test sample is 50 mm. Then, the end of the cellophane tape to which the cellophane tape is not attached is attached to the chuck, the cellophane tape is set so that the angle between the adhered surface and the non-adhered surface is 90 degrees, and the cellophane tape is pulled at a speed of 100 mm / min and peeled. . At this time, the speed at which the cellophane tape is peeled off and the stainless steel plate to which the test sample is attached are moved at the same speed, so that the non-sticking surface of the cellophane tape and the test sample surface are always at 90 degrees. After the test, the state of the coating film is examined and evaluated according to the following evaluation criteria. ：: The coating film was not broken and no peeling occurred from the PET film. ×: The coating film was broken and a part of the coating film was adhered to the cellophane tape.

[0051]

[Table 1]

As shown in Table 1, the haze was 13%.
The transparent conductive films (samples 1 to 4) of the present invention using the following PET films (PET films A to D)
In each case, the haze was 15% or less, and for example, it was confirmed that the film had sufficient transparency when used for a touch panel. Further, the transparent conductive film of the present invention (Sample 1)
In Nos. To 4), it was confirmed that the strength of the transparent conductive layer was high and the adhesion to the PET film was good.

Example 2 First, the primary particle size was 10 to 30.
300 parts by weight of methanol was added to 100 parts by weight of ITO fine particles (density: 6.9 g / cm ³ , manufactured by Dowa Mining Co., Ltd.), and the medium was dispersed as zirconia beads by a disperser to prepare a conductive paint A. did.

In addition, ITO having a primary particle size of 60 to 80 nm
Fine particles (density: 7.0 g / cm ³ , manufactured by Dowa Mining Co., Ltd.) 1
To 100 parts by weight, 300 parts by weight of methanol was added, and the medium was dispersed as zirconia beads with a disperser to prepare a conductive paint B. The particle size of the ITO fine particles was measured using SE.
M (scanning electron microscope) at a magnification of 400,000 times.

Next, PE having a haze of 1% and a thickness of 50 μm was used.
The conductive coating liquid A and the conductive coating B were applied on a T film using a bar coater and dried (60 ° C.). The two types of films thus obtained are hereinafter referred to as pre-compression ITO films. The thickness of the ITO-containing coating film of these pre-compression ITO films was 1.7 μm.
Met.

Next, the pre-compression ITO film was sandwiched between metal rolls (having a roll surface subjected to hard chromium plating), and was heated at room temperature (23 ° C.) for 3 times per unit area.
Compression was performed at 47 N / mm ² , and the roll was rotated to compress at a feed speed of 5 m / min. By compressing the ITO film in this way, transparent conductive films (samples A and B) each having a transparent conductive layer were obtained. The thickness of the transparent conductive layer after compression was 1.0 μm for both Sample A and Sample B.

The transparent conductive films (samples A and B) produced as described above were prepared in the same manner as in Example 1.
The haze degree and surface electric resistance were measured, and the results are shown in Table 2 below.
It was shown to. A 90 ° peel test was performed in the same manner as in Example 1, and the results are shown in Table 2 below.

[0058]

[Table 2]

As shown in Table 2, the primary particle size was 50 n.
The transparent conductive film (sample A) of the present invention prepared using the conductive paint A containing ITO fine particles having a particle size of m or less has a low haze of 6% and a sufficient surface electric resistance of the transparent conductive layer. PET with low strength and high strength of transparent conductive layer
It was confirmed that the adhesion to the film was also good. On the other hand, the transparent conductive film (sample B) produced using the conductive paint B containing large ITO fine particles having a primary particle size exceeding 50 nm has a low surface electric resistance of the transparent conductive layer and a transparent conductive film. The strength of the layer was high and the adhesion to the PET film was good, but the haze was as high as 19%.

[0060]

As described in detail above, according to the present invention,
The haze degree of the transparent support of the transparent conductive film having a transparent conductive layer on at least one surface of the transparent support is 0.1 to
13%, and the transparent conductive layer has a primary particle size of 50 nm.
Since the conductive layer is a compressed layer of the following conductive fine particles, the conductive fine particles are compressed in the transparent conductive layer to make sufficient contact with the conductive fine particles, and the transparent conductive layer has a low electric resistance. In addition, since the conductive fine particles are compressed, the adhesion between the transparent support and the transparent conductive layer is strong, and long-term use is possible. Further, as the transparent support, it is possible to use a transparent support such as a resin film, and the transparent conductive film of the present invention can be applied to a large area by changing an application device and a compression device. And so on.

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Claims (4)

[Claims] 1. A transparent support and a transparent conductive film having a transparent conductive layer on at least one surface of the transparent support, wherein the transparent support has a haze in the range of 0.1 to 13%. The transparent conductive layer is a compressed layer of conductive fine particles having a primary particle size of 50 nm or less. 2. The transparent conductive film according to claim 1, wherein the transparent support is a resin film. 3. The haze degree of the transparent conductive film is 15%.
The transparent conductive film according to claim 1 or 2, wherein: 4. The transparent conductive layer according to claim 1, wherein the conductive fine particles are formed by compressing the conductive fine particles with a compressive force of 44 N / mm ² or more. Transparent conductive film.