JP2001328200A - Transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film which has a low surface electric resistance value and is excellent in conductivity and also in transparency and suitable for an antistatic use particularly, making the most of a coating method which facilitates forming of a conductive film of a large area and the equipment for which is simple, has high productivity and can be manufactured at a low cost. SOLUTION: The transparent conductive film is constituted by forming on a substrate a conductive layer containing particulates of an antimony-doped tin oxide(ATO). The surface electric resistance value of the film is 103-106 Ω/(square) and the visible light transmittance thereof is 75% or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a transparent conductive film. The transparent conductive film of the present invention is suitably applied to a CRT front panel, a building material glass, a vehicle glass, a semiconductor clean room resin plate, etc., mainly for antistatic purposes.

[0002]

2. Description of the Related Art A transparent conductive film in which a layer containing a conductive material is formed on a support is mainly produced by a sputtering method. There are various means in the sputtering method, for example, accelerated collision of inert gas ions generated by DC or high-frequency discharge in a vacuum to the target surface,
Means include a method in which atoms constituting the target are knocked out from the surface and deposited on the surface of the support to form a transparent conductive layer.

[0003] The sputtering method is excellent in that a conductive layer having a low surface electric resistance can be formed even with a relatively large area. However, there is a problem that the apparatus is large and the film forming speed is low. In the future, as the area of the conductive layer increases, the scale of the device is expected to increase. Increasing the scale of the apparatus causes a technical problem that a higher degree of control is required for the control accuracy, and a problem in manufacturing efficiency such as an increase in manufacturing cost. At present, the number of targets is increased to increase the film formation rate, but this also contributes to the increase in the scale of the apparatus.

[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 resin is coated on a support and dried to form a conductive layer. In the coating method, a large-area conductive layer is easily formed, the apparatus is simple, the productivity is high, and the manufacturing cost is low as compared with the sputtering method. In a conductive film formed by a coating method, conductive particles formed in a conductive layer come into contact with each other to form an electrical path, thereby exhibiting conductivity.

Conventionally, in the production of a transparent conductive film by a coating method, it has been considered that a conductive layer cannot be formed unless a large amount of a binder resin is used. Therefore, there is a problem that contact between the conductive fine particles is hindered by the binder resin, and the resulting transparent conductive film has a high electric resistance value (poor in conductivity), and its use has been limited. Further, it is said that when a binder resin is not used, a conductive layer that can withstand practical use cannot be formed unless the conductive material is sintered at a high temperature.

As a conventional coating method, for example, Japanese Patent Application Laid-Open No. 9-1
No. 09259 discloses a first step of applying a conductive paint composed of a conductive powder and a binder resin on a transfer plastic film and drying the conductive paint to form a conductive layer. １００100 kg / cm ² ), heating (7
A method for producing an antistatic transparent conductive film or sheet comprising a second step of treating (0 to 180 ° C.) and a third step of laminating this conductive layer on a plastic film or sheet and thermocompression bonding is disclosed.

In the above manufacturing method, a conductive paint containing a large amount of a binder resin is used. That is, when an inorganic conductive powder is used as the conductive powder, the binder 100
When the conductive powder is used in an amount of 100 to 500 parts by weight and the organic conductive powder is used in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the binder. Since a large amount of binder resin is used, a transparent conductive film having a low electric resistance cannot be obtained by the technique disclosed in the above publication. Even in the case where the amount of the binder resin is the least, the binder is 100 parts by weight with respect to 500 parts by weight of the inorganic conductive powder.
The amount is about 110 for the binder with respect to 0.

Japanese Patent Application Laid-Open No. 8-199096 discloses that
Consisting of tin-doped indium oxide (ITO) powder, solvent, coupling agent, metal organic or inorganic acid salt,
There is disclosed a method for producing a transparent conductive film-coated glass plate, in which a conductive film forming paint containing no binder 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 value of the conductive film is reduced. However, since it is necessary to perform the baking step at a temperature of 300 ° C. or higher, it is difficult to form a conductive film on a support such as a resin film. The resin film is deformed, melted, carbonized, or burns at medium to high temperatures. Although it varies depending on the type of resin film, for example, a temperature of about 130 ° C. is considered to be the limit of heating in a polyethylene terephthalate (PET) film.

As a manufacturing method other than the coating method, for example, Japanese Unexamined Patent Publication (Kokai) No. Hei 6-13785 discloses that at least a part, preferably all of the voids of a skeleton structure composed of a conductive substance (metal or alloy) powder are used. There is disclosed a conductive film composed of a powder compression layer filled with a resin and a resin layer below the powder compression layer. According to that, when forming a film on a plate material,
First, when a resin, a powdery substance (metal or alloy) and a plate material as a member to be processed are vibrated or stirred 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 of the member to be processed. Subsequently, the powder material is captured and fixed to the resin layer by the adhesive force of the resin layer. Further, 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, even in this technique, since a considerable amount of resin is required to obtain the effect of fixing the powder compression layer, it is difficult to obtain a conductive film having a low electric resistance value. Also, the production method is more complicated than the coating method.

[0010] Still another production method is disclosed in Japanese Patent Application Laid-Open No. 9-10 / 1990.
No. 7195 discloses a method of forming a conductive short fiber-resin integrated layer by sprinkling conductive short fibers on a film such as PVC and depositing the same, followed by pressure treatment. The conductive short fiber is a short fiber such as polyethylene terephthalate obtained by applying a nickel plating or the like to the short fiber. The pressing operation is preferably performed under a temperature condition at which the resin matrix layer shows thermoplasticity.
A high temperature heating and low pressure condition of g / cm ² is disclosed.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a conductive film having a large area can be easily formed, the apparatus is simple, the productivity is high, and the advantages of the coating method that can be manufactured at low cost can be obtained at a low cost. An object of the present invention is to provide a transparent conductive film having low surface electric resistance, excellent conductivity, and excellent transparency using materials abundant in earth resources.

For example, tin-doped indium oxide (IT
O) is currently used as a conductive material because of its extremely low electrical resistance among oxides. However, indium is a small resource and is expensive, so its electrical resistance is higher than ITO but abundant as a resource. ATO containing pure tin (Sn)
It is industrially preferable to realize an electric resistance close to that of ITO by using GaN.

[0013]

In order to solve the above problems, the following inventions are provided.

(1) Antimony-doped tin oxide (ATO)
A transparent conductive film in which a conductive layer containing fine particles is formed on a support, and has a surface electric resistance of 10 ³ to 10 ⁶ Ω.
/ □, a transparent conductive film having a visible light transmittance of 75% or more.

(2) The transparent conductive film having a haze value of 1 to 10%.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The transparent conductive film of the present invention is obtained by forming a conductive layer on a support. The conductive layer contains antimony-doped tin oxide (ATO) fine particles. In the present invention, since the conductive layer contains antimony-doped tin oxide (ATO) fine particles, for example, an embodiment in which an ATO crystal film is formed in the conductive layer is not included in the present invention. The thickness of the conductive layer is not particularly limited, and cannot be said unconditionally depending on the use and purpose as the transparent conductive film, but is preferably about 0.1 to 10 μm.

The support is not particularly limited, and various supports such as a resin film, glass, and ceramics can be used, but a support having high transparency and flexibility is preferable. From these points, a resin film is preferably used. Examples of the resin film include a polyester film such as polyethylene terephthalate (PET), a polyolefin film such as polyethylene or polypropylene, a polycarbonate film, an acrylic film, a norbornene film ("ARTON" manufactured by JSR Corporation) and the like. Among them, a PET film is particularly preferred. The thickness of the support is not particularly limited, but is preferably about 10 to 200 μm.

The transparent conductive film of the present invention having the above-mentioned structure has such characteristics that the surface electric resistance value is 10 ³ to 10 ⁶ Ω / □ and the visible light transmittance is 75% or more.

In the present invention, the surface electric resistance was measured using Loresta AP (MCP-T400) manufactured by Mitsubishi Yuka Co., Ltd. The measurement sample is a conductive film of 5 cm
It was cut out into a size of × 5 cm and used.

The visible light transmittance is a value obtained by measuring the transmittance of the object to be measured in the visible light region with a spectrophotometer. The visible light transmittance in the present invention indicates the visible light transmittance of the entire conductive film including the conductive layer and the support.

The visible light transmittance is more preferably 80.
% Or more. The upper limit is about 95%.

The transparent conductive film of the present invention preferably has a haze value of 1 to 10%, more preferably 1 to 5%. Here, the haze value (cloudiness value) refers to the ratio of the transmittance of the diffused light excluding the straight light to the total light transmittance of the light source. Therefore, the lower the haze value, the higher the transparency. Haze value is JIS K71
It can be obtained by the following equation (1) defined in Equation (5).

[0024]

H = Td / Tt (where H is the haze, Tt is the total light transmittance, and Td is the diffuse transmittance) Examples of the transparent conductive film of the present invention having the above characteristics include a support On the above, a layer formed by compressing a layer containing conductive fine particles such as ATO fine particles to form a conductive fine particle compression layer is exemplified as a preferred embodiment, but it is not limited to the above embodiment. Of course.

The method for producing the transparent conductive film of the present invention is not particularly limited, but is preferably produced, for example, by the following method.

That is, a coating material in which conductive fine particles are dispersed is applied on a support, dried to form a conductive fine particle-containing layer, and then the conductive fine particle-containing layer is compressed to obtain a conductive fine particle-compressed layer. And a method for producing a transparent conductive film.

As the conductive fine particles, antimony-doped tin oxide (ATO) fine particles are used as an essential component in the present invention. The particle diameter of the ATO fine particles varies depending on the degree of scattering required according to the application of the conductive film, and also varies depending on the shape of the particles, and cannot be unconditionally determined, but is generally 1 μm or less, preferably 0.5 μm or less. , 5
100 nm is more preferred.

The liquid (dispersion medium) in which the conductive fine particles are dispersed is not particularly limited, and various known dispersion media can be used. For example, 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; And 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; halogenated hydrocarbons such as ethylene chloride and chlorobenzene; Among them, a dispersion medium having polarity is preferable. Particularly, alcohols such as methanol and ethanol, and those having an affinity for water such as amides such as NMP have good dispersibility even without using a dispersant. Therefore, it is preferably used. One or more of these dispersion media can be used. In addition, a dispersant may be used depending on the type of the dispersion medium.

Water can also be used as a dispersion medium. When water is used, the support needs to be hydrophilic.
Since the resin film is usually hydrophobic, it easily repels water, and it is difficult to obtain a uniform layer. When the support is a resin film, it is necessary to mix alcohol with water or to make the surface of the support hydrophilic.

The amount of the dispersion medium to be used is not particularly limited as long as the dispersion of the conductive fine particles (paint, conductive paint) has an appropriate viscosity suitable for application. In particular,
Dispersion medium 100 to 10 per 100 parts by weight of conductive fine particles
The amount is preferably about 000 parts by weight, but can be appropriately changed depending on the types of the conductive fine particles and the dispersion medium.

The dispersion of the conductive fine particles in the dispersion medium can be performed by a known dispersion means such as 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. In addition, care should be taken not to mix impurities such as dust during dispersion.

The liquid (coating material) in which the conductive fine particles are dispersed is preferably used in a range of less than 25 when the volume of the conductive fine particles is 100, where the volume of the resin for the binder is represented by the volume before dispersion. , More preferably less than 20,
Particularly preferably, it is less than 3.7, and most preferably 0. The resin has an effect of reducing the scattering of the conductive film, but on the other hand, increases the electric resistance value of the conductive film. This is because the insulating resin inhibits the contact between the conductive fine particles, and when the amount of the resin is large, the contact between the fine particles is prevented, and the electron transfer between the fine particles is inhibited. Therefore, the resin is preferably used within the above-mentioned volume range in consideration of both improvement of transparency and securing of conductivity between the conductive fine particles.

The volume of the conductive fine particles and the volume of the binder resin are not apparent volumes but true volumes. The true volume is determined by using a device such as a pycnometer based on JIS Z 8807, and calculating from (weight of material used) / (density of material used). In this way, defining the amount of resin to be used by volume rather than weight reflects the reality by considering how the resin is present with respect to the conductive fine particles in the conductive layer obtained after compression. Because you do.

In the conventional coating method, since strong compression of the coating film in the present production method as described later is not performed, it is necessary to contain a large amount of resin as a binder in order to obtain the mechanical strength of the coating film. there were. When an amount of resin that can serve as a binder is contained, contact between the conductive fine particles is hindered by the binder, electron transfer between the fine particles is hindered, and conductivity decreases.

The 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, fluorine-based polymer, silicone resin, acrylic resin, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose diacetyl cellulose,
Examples thereof include polyvinyl chloride, polyvinylpyrrolidone, polyethylene, 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. As the density of the resin increases, the volume does not increase even when the amount used increases, so that the requirements of the present invention are easily satisfied.

Various additives may be added to the dispersion of the conductive fine particles as long as the conductivity is not impaired. Examples of these additives include an ultraviolet absorber, a surfactant, and a dispersant.

Next, a dispersion (coating material) of the conductive fine particles is coated on a support and dried to form a conductive fine particle-containing layer.

The application of the conductive fine particle dispersion (paint) onto the support is not particularly limited, and can be performed by a known method. 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 support by spraying or spraying.

The drying temperature depends on the type of dispersion medium 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 is likely to occur, while if the temperature is higher than 150 ° C, the resin film (support) may be deformed. Also, care should be taken so that impurities do not adhere to the surface of the fine particles during drying.

The thickness of the conductive fine particle-containing layer after coating and drying may be about 0.1 to 10 μm, depending on the compression conditions in the next step and the use of the finally obtained conductive film.

As described above, when the conductive fine particles are dispersed in a dispersion medium, applied, and dried, a uniform layer is easily formed.
When applying and drying a dispersion of these conductive fine particles,
The fine particles form a layer even when no binder is present in the dispersion. The reason why a layer can be formed without containing a binder is not always clear, but when the liquid in the coating film is dried by drying, the fine particles gather together due to capillary force, and further, the fine particles It is considered that a layer is formed because the specific surface area is large and the cohesive force is strong. However, the strength of the layer at this stage is weak. Further, the resistance value of the conductive film is high, and the variation of the resistance value is large.

Next, the formed layer containing conductive fine particles is compressed to obtain a compressed layer of conductive fine particles. By compressing, the strength of the coating film can be improved. That is,
The compression increases the contact points between the conductive fine particles and increases the contact surface, thereby increasing the strength of the coating film. Since the fine particles originally have a property of easily aggregating, they become a strong layer by being compressed. In a conductive film, the strength of the coating film increases and the electrical resistance decreases.

The compression is applied to the layer formed on the support by 4
The compression is preferably performed with a compression force of ⁴ N / mm ² or more, more preferably 135 N / mm ² or more, and particularly preferably 180 N / mm ² or more.
N / mm ² or more. If it is less than 44 N / mm ² , the conductive fine particle-containing layer cannot be sufficiently compressed, and it is difficult to obtain a conductive film having excellent conductivity. The higher the compressive force, the higher the coating film strength and the better the adhesion to the support. In the conductive film, a film having more excellent conductivity can be obtained, the strength of the coating film is improved, and the adhesion between the coating film and the support becomes strong. Since the higher the compression force, the higher the pressure resistance required for the device, the compression force up to 1000 N / mm ² is generally appropriate. In addition, compress at normal temperature (15-40
C.). The compression operation at a temperature near normal temperature is one of the advantages of the present invention.

The compression means is not particularly limited.
Although it can be performed by a sheet press, a roll press, or the like, it is preferable to use 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 suitable because it is uniformly applied with a high pressure and can be produced in a roll-to-roll manner because of its high productivity.

The roll temperature of the roll press machine is set to normal temperature (15
-40 ° C) is preferred. In a heated atmosphere or in compression (hot press) in which a roll is heated, if the compression pressure is increased, a problem such as expansion of the resin film occurs. In order to prevent the resin film of the support from stretching under heating,
When the compression pressure is reduced, the mechanical strength of the coating film decreases.
In conductive films, the mechanical strength of the coating decreases,
Electric resistance increases. When it is necessary 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 must be within a temperature range where the film does not easily elongate. Generally, the temperature range is preferably 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. In the case of continuous compression by a roll press machine, it is also preferable to adjust the temperature so that the roll temperature does not rise due to heat generation.

The glass transition temperature of the resin film is
It is determined by measuring dynamic viscoelasticity and refers to the temperature at which the mechanical loss of the main dispersion peaks. For example, regarding 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 can be applied. If the roll surface is soft, the functional fine particles may be transferred to the roll at the time of compression. Therefore, it is preferable to treat the roll surface with a hard film.

Thus, a compressed layer of conductive fine particles is formed on the support. The thickness of the conductive fine particle compression layer is
Although it depends on the application, it may be about 0.1 to 10 μm.
The compressed layer of the conductive fine particles contains a resin having a volume of less than 25 when the volume of the conductive fine particles is 100, depending on the volume ratio of the conductive fine particles and the resin used in preparing the dispersion. Is preferred. In addition, in order to obtain a compressed 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. Furthermore, in the present invention, it is of course possible to form conductive layers on both surfaces of the support. The transparent conductive layer obtained in this manner exhibits excellent conductivity, has a practically sufficient film strength despite being prepared without using a large amount of binder resin as in the conventional case, and Excellent adhesion.

In the conductive film of the present invention, a hard coat layer as a protective layer may be provided on the conductive layer if desired. The hard coat layer can be formed by applying a solution obtained by dissolving a hard coat agent in a solvent as necessary, drying and curing the conductive layer.

The hard coating agent is not particularly limited, and various known hard coating agents can be used. For example, a thermosetting hard coat agent such as a silicone-based, acrylic-based, or melamine-based can be used. Among them, silicone-based hard coat agents are excellent in that high hardness can be obtained.

Further, a radical polymerizable hard coating agent such as an unsaturated polyester resin or an acrylic resin, an epoxy resin,
An ultraviolet-curable hard coat agent such as a vinyl ether-based cationic polymerizable hard coat agent may be used. The UV-curable hard coat agent is preferable from the viewpoint of productivity such as curing reactivity. Among these, an acrylic radical polymerizable hard coat agent is desirable in consideration of curing reactivity and surface hardness.

The conductive film of the present invention is suitably applied to a CRT front panel, a building glass, a vehicle glass, a semiconductor clean room resin plate, etc., mainly for antistatic purposes.
For example, it is possible to effectively prevent dust from being adsorbed by being adhered to an adherend that has not been subjected to an antistatic treatment.

[0054]

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.

In the following Examples, each characteristic evaluation was performed by the following methods.

[Surface electric resistance] Lor manufactured by Mitsubishi Yuka Co., Ltd.
It was measured using esta AP (MCP-T400). The measurement sample was prepared by cutting a conductive film into a size of 5 cm × 5 cm.

[90 degree peel test] A 90 degree peel test was performed to evaluate the adhesion between the conductive film and the support and the strength of the conductive film. This will be described with reference to FIG.

The conductive film (1b) is formed on one surface of the support (1b).
a) is formed, and a double-sided tape (2) is attached to the surface opposite to the surface on which the conductive film is formed, and this is sized to 25 mm × 1.
A sample cut into 00 mm was used as a test sample (1). The double-sided tape surface side of this test sample (1) is stuck on a stainless steel plate (3), and cellophane tapes (4) for fixing are attached to both ends in the longitudinal direction so that the test sample (1) does not peel off. Affixed (FIG. 1 (a)).

Next, as shown in FIG. 1B, one end of a cellophane tape (width: 12 mm, No. 29, manufactured by Nitto Denko Corporation) (5) was placed on the conductive film (1a) surface as a test sample ( 1) Pasted so as to be parallel to the long side. The length of the sticking surface between the cellophane tape (5) and the test sample (1) was 50 mm. The other end of the cellophane tape (5) was attached to a tensiometer (6), and the cellophane tape (5) was set so that the angle between the sticking surface and the non-sticking surface (5a) was 90 degrees. Next, the cellophane tape (5) was pulled off at a speed of 100 mm / min by a tensiometer (6) to peel it off.
At this time, the speed at which the tape (5) was peeled off and the stainless steel plate (3) on which the test sample (1) was adhered were moved at the same speed, and the non-adhering surface (5) of the cellophane tape (5) was moved.
The angle between a) and the test sample (1) face was always 90 °. The force (F) required for peeling was measured by a tensiometer (6) (FIG. 1 (b)).

After the test, the peeled conductive film surface and the cellophane tape surface were examined. When the adhesive is present on both surfaces, the conductive layer was not destroyed, but the adhesive layer of the cellophane tape was destroyed, that is, the force (F) required when the strength of the adhesive was removed. Therefore, the strength of the conductive film is equal to or higher than the value (F).

In this test, the upper limit of the strength of the adhesive was 6
N / 12mm, the evaluation result is 6N / 12m
The symbol "m" indicates that the adhesive is present on both surfaces as described above, and the adhesiveness and the strength of the conductive film are 6N / 1.
2 mm or more. If the value is smaller than this value, it means that there is no adhesive on the surface of the conductive film and the conductive film is partially adhered to the surface of the cellophane tape.

[Visible light transmittance] Integrating sphere (manufactured by JASCO Corporation) on a spectrophotometer (V-570 manufactured by JASCO Corporation)
The transmittance of the transparent conductive film in the visible light region was measured, and the visible light transmittance was determined according to JIS R3106.

[Haze] The haze value of the transparent conductive film was measured using a haze meter (TC-H3 DPK type: manufactured by Tokyo Denshoku Co., Ltd.) according to JIS K 7105.

Example 1 ATO fine particles having an average primary particle diameter of 20 nm or less (“SN-100P”, manufactured by Ishihara Sangyo Co., Ltd.)
100 parts by weight) and 300 parts by weight of ethanol were added, and the medium was dispersed as zirconia beads using a disperser.
The obtained dispersion liquid (coating liquid) was applied on a PET film having a thickness of 50 μm using a bar coater, and dried by sending warm air at 50 ° C. to form an ATO-containing coating film. The thickness of the ATO-containing coating film thickness was about 2.1 μm.

Next, using a roll press machine, the film is pressed at a pressure of 7 per unit length in the film width direction.
50N / mm, pressure 395N / m per unit area
compressed in m ^2, 5 m / min feed rate, compressed ATO
A film was obtained. The thickness of the ATO-containing coating film after compression was about 1.3 μm.

The characteristics of the compressed ATO film were evaluated by the evaluation methods described above. The surface electric resistance was 12.5 × 10 ³ Ω / □, and the visible light transmittance was 84.
% And a haze value of 3.1%. When the film strength was calculated from the results of the 90 degree peel test, the film strength was 6N / 1.
It was 2 mm or more.

Example 2 A 3 μm thick silicone hard coat layer (GE Toshiba Silicone Co., Ltd., Tosguard 51) was formed on the ATO-containing coating film of the ATO film of Example 1.
0).

This was evaluated for characteristics according to the evaluation methods described above. As a result, the visible light transmittance was 85% and the haze value was 3.4%. When the coating strength was calculated from the results of the 90 degree peel test, the coating strength was 6 N / 12 mm or more.

(Examples 3 to 6) Compressed ATO films were produced in the same manner as in Example 1 except that the thickness of the coating film and the compressive force were changed, and the characteristics were evaluated. . Table 1 shows the results.

[0070]

[Table 1]

(Comparative Example 1) ATO fine particles having an average primary particle diameter of 20 nm or less (“SN-100P”, manufactured by Ishihara Sangyo Co., Ltd.)
100 parts by weight of an acrylic resin (“MT408-4”).
2 ", solid content concentration (NV) = 50%, Taisei Kako Co., Ltd.
100 parts by weight) and methyl ethyl ketone / toluene /
Cyclohexanone = 1/1/1 (weight ratio) mixed solvent 4
00 parts by weight, and this was used as a coating solution (ATO / acrylic resin = 2: 1, NV = 25%).
It was applied on a PET film having a thickness of μm using a bar coater, and dried by blowing warm air at 50 ° C. to form an ATO-containing coating film. The thickness of the ATO-containing coating film was about 2.0 μm.

Then, using a roll press machine, the film is pressed at a pressure of 7 per unit length in the film width direction.
50N / mm, pressure 395N / m per unit area
compressed in m ^2, 5 m / min feed rate, compressed ATO
A film was obtained. The thickness of the ATO coating film (conductive layer) after compression was about 1.3 μm.

The characteristics of the compressed ATO film were evaluated according to the evaluation methods described above. As a result, the surface electric resistance was 1.8 × 10 ⁶ Ω / □, the visible light transmittance was 85%,
The haze value was 3.0%. When the coating strength was calculated from the results of the 90 degree peel test, the coating strength was 6N / 12m.
m or more.

[0074]

As described above in detail, according to the present invention, a transparent material including a support and a conductive layer provided thereon, which has a low surface electric resistance value, a high visible light transmittance and an excellent transparency. A conductive film is obtained. The transparent conductive film of the present invention is suitably applied to a CRT front panel, a building material glass, a vehicle glass, a semiconductor clean room resin plate, etc., mainly for antistatic purposes.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a 90-degree peel test in an example.

[Explanation of symbols]

 Reference Signs List 1 Test sample 1a Conductive film 1b Support 2 Double-sided tape 3 Stainless steel plate 4 Cellophane tape for fixing 5 Cellophane tape 5a Cellophane tape non-sticking surface 6 Tensiometer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AA28A AA29A AA33A AK01B AK42 AS00B AT00B BA02 CA21A DE01A EH462 EJ862 GB07 GB32 JG01A JG04 JN01 YY00 5G307 FA01 FA02 FB01 FC09 FC10

Claims (2)

[Claims] 1. A transparent conductive film in which a conductive layer containing antimony-doped tin oxide (ATO) fine particles is formed on a support, and has a surface electric resistance value of 10 ³ to 10 ⁶ Ω /.
□, a transparent conductive film having a visible light transmittance of 75% or more. 2. The method according to claim 1, wherein the haze value is 1 to 10%.
The transparent conductive film according to the above.