JPH1158598A - Transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high transparency and good conductivity by a method in which a conductive metal thin film layer is formed on a transparent polymer base material, and a cured conductive coating film layer in which conductive metal particles of a particle size of a specified value or less are dispersed in an ultraviolet curable resin is formed on the thin film layer. SOLUTION: In a transparent conductive film, on a transparent polymer base material is formed a thin conductive metal film layer, and on it formed is a cured conductive coating film layer in which conductive metal fine particles 0.5 micron or less in particle size are dispersed in an ultraviolet curable resin containing a multifunctional acrylate having at least two acryloyl groups in the molecule as a main component. The particle size of the conductive metal fine particles is necessary to be 0.5 micron or less to keep transparency. When the particle size exceeds 0.5 micron, haze is generated in the film to make its use difficult. The ultraviolet curable conductive coating to be used is obtained by a process in which the ultraviolet curable resin and, in addition, a photopolymerization initiator are added into a solution in which metal fine particles are dispersed in an organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a transparent plastic film having excellent conductivity. More specifically,
The present invention relates to a hard-coated plastic film that is transparent, has low surface electric resistance, and has excellent conductivity.

[0002]

2. Description of the Related Art Most of the films currently used in the market are mainly composed of polymer plastics, and generally have a surface resistivity of 10 ¹⁴ Ω / □ or more and are therefore substantially insulators. For this reason, various attempts have been made to conduct electroconductivity on these films to impart conductivity to the films.For example, a method in which a surfactant is contained in the film, a method of treating the surface with a surfactant, aluminum Attempts have been made to attach metal foils such as, a method of depositing metal, a method of kneading carbon into a film resin, a method of wiring a metal wire or a carbon wire in a film, and a method of including a conductive polymer in a resin. ing. All of these methods lower the electrical resistance of the entire film to facilitate the movement of electrons and impart conductivity, such as antistatic bags, touch panels, surface heating elements, thin film resistors, and electromagnetic shielding. Its use is expanding to bodies, optical filters, electrodes of liquid crystal displays, and the like.

However, when a film is treated with a surfactant, the conductivity tends to change depending on the environment of the outside air, particularly temperature and humidity, and the conductivity decreases with time due to exposure to the environment. In addition, the method of laminating a metal foil or the method of vapor deposition of a metal has a disadvantage that it is necessary to further cover the surface with a resin film in order to prevent surface oxidation and damage, which impairs the conductivity of the surface. Also, the method of kneading carbon into resin has a disadvantage in that it absorbs visible light and loses transparency. The method of wiring a metal wire or a carbon wire in a matrix in a film has a drawback that the processing method is complicated, and in the case of a transparent film, the wiring is visible and lacks visibility and aesthetics. In particular, when distributing a conductive filler such as carbon or metal in a resin, it is necessary to use a large amount of the conductive filler in order to obtain high conductivity.
As a result, there was a defect that transparency had to be sacrificed. Especially when used for optical films, it is necessary to achieve both high transparency and excellent conductivity,
This has been difficult with conventional techniques.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hard coat film having both high transparency and excellent conductivity without the above-mentioned drawbacks.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a conductive material was formed on a transparent substrate made of a polymer by a sputtering method, a vapor deposition method, an ion plating method or the like. A metal thin film layer is provided, and a film obtained by applying and curing a conductive paint obtained by dispersing a conductive metal having a particle diameter of 0.5 μm or less in an ultraviolet curable resin,
The present inventors have found that they are excellent in both visible light transmission and conductivity, and have completed the present invention. That is, the present invention provides (1) providing a conductive metal thin film layer on a transparent substrate made of a polymer,
Further, a transparent conductive film provided thereon with a cured film layer of a conductive paint in which conductive metal fine particles having a particle diameter of 0.5 μm or less are dispersed in an ultraviolet curable resin, (2) the conductive metal is IT
O (tin-doped indium oxide), ATO (antimony-doped tin oxide), zinc antimonate, or silver (1)
And (3) the film of (1), wherein the UV-curable resin is mainly composed of a polyfunctional acrylate having two or more acryloyl groups in a molecule.

In the transparent conductive film of the present invention, a conductive metal thin film layer is provided on a transparent substrate made of a polymer, and conductive metal fine particles having a particle diameter of 0.5 μm or less are further cured by ultraviolet light. A cured film layer of a conductive paint dispersed in a mold resin is provided. Examples of the transparent substrate made of a polymer include substrates made of polyester, polycarbonate, triacetate, polyurethane, polyvinyl chloride, polyacrylonitrile, polyimide, polyethersulfone, and the like. The thickness of the base material is 5 μm to 10 m.
m, preferably about 10 to 500 μm.

The conductive metal thin film layer is a thin film of a metal having conductivity, and preferably has a thickness of 3 nm to 200 nm and a range of 5 nm to 100 nm from the viewpoint of transparency. Examples of conductive metals that can be used include, for example, ITO (tin-doped indium oxide), ATO (antimony-doped tin oxide), zinc antimonate (composite of antimony oxide and zinc oxide),
Silver, copper, platinum, gold, nickel, tin oxide, tin, zinc oxide, zinc and the like can be mentioned, but ITO, ATO, zinc antimonate and silver are preferred from the viewpoint of price and performance, particularly transparency.

The conductive paint used in the present invention is an ultraviolet-curable conductive paint in which conductive metal fine particles having a particle diameter of 0.5 μm or less and a photopolymerization initiator are dispersed in an ultraviolet-curable resin. The conductive metal fine particles are 0.5 μm in order to maintain transparency.
The particle size must be 0.1 μm or less, and if the particle size is larger than that, haze is generated in the film, making it difficult to use. It is. Examples of the conductive metal added to the conductive paint include the same as described above.

The photopolymerization initiator is not particularly limited, and various known ones can be used. As specific examples, Irgacure 184, Irgacure 651 (manufactured by Ciba-Geigy), Darocure 1173 (manufactured by Merck),
Examples thereof include benzophenone, methyl benzoylbenzoate, P-dimethylbenzoate, and thioxanthone.

The UV-curable resin is not particularly limited as long as it is a (meth) acrylate having at least one (meth) acryloyl group in the molecule, but particularly has two or more acryloyl groups in the molecule. When a polyfunctional acrylate is used as a main component, there is an effect that the hardness of the cured conductive paint is high and the scratch resistance of the film is significantly improved. Specific examples of the acrylate include neopentyl glycol diacrylate, 1,6 hexanediol acrylate, trimethylolpropane triacrylate, ditrimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate. Polyacrylate, epoxy acrylate such as diacrylate of bisphenol A diglycidyl ether, diacrylate of neopentyl glycol diglycidyl ether, diacrylate of 1.6 hexanediol diglycidyl ether, polyhydric alcohol and polycarboxylic acid and / or Polyester acrylate obtained by esterifying the anhydride and acrylic acid Polyhydric alcohols and urethane acrylate obtained by reacting a polyisocyanate and a hydroxyl-containing acrylate, may be mentioned polysiloxane acrylate. The above polymerizable acrylates may be used alone or in combination of two or more.

The ultraviolet-curable conductive coating material used in the present invention is generally prepared by gradually stirring, while stirring, a solution having fine metal particles finely dispersed in an organic solvent and having a (meth) acryloyl group in the molecule. It is obtained by adding a curable resin and further adding a known photopolymerization initiator. In order to prevent aggregation of the metal fine particles and further improve the dispersibility, a dispersant is added as necessary.

Specific examples of dispersants that can be used include cationic surfactants, weak cationic surfactants, nonionic surfactants, amphoteric surfactants, and carboxylic acid surfactants. Oxide-added alkylamines, alkylene oxide-added ethylenediamines, and polycarboxylic acid-based surfactants are preferably used.

The UV-curable conductive paint used in the present invention can be copolymerized with the main chain or terminal of an acrylic resin, a polyester resin, a butyral resin or the like in order to further improve the adhesion to the underlying metal thin film. It is possible to add an appropriate amount of an oligomer having a terminal group.

Further, in the conductive paint, if necessary,
Various organic solvents, leveling agents, defoamers can be added,
It must be added according to the range and method in which the metal fine particles do not aggregate. When the metal is aggregated, a transparent film cannot be obtained but becomes haze, and the effect is reduced.

The conductive metal content in the conductive paint is 10 to 95% (% by weight, the same applies hereinafter) based on the total solid content of the paint, the UV curable resin content is 5 to 90%, The oligomer is 0 to 50%, preferably 5 to 50%, and the dispersant is 0 to 40%, preferably 0.05%, based on the conductive metal.
It is used in the range of ％ 40%. The photopolymerization initiator is used in an amount of 2 to 20%, preferably 3 to 10%, based on the ultraviolet curable resin.

The transparent conductive film of the present invention can be produced, for example, by the following method. First, the transparent substrate is placed in a sealed container, and the pressure is reduced to 10 ^-8 to 10 ^-5 Torr, and the conductive material is made conductive in the gas phase by a known method such as sputtering, vacuum deposition, ion plating, or plasma CVD. The metal is deposited to form a conductive metal thin film on the substrate. Subsequently, an ultraviolet-curable paint containing fine particles of a conductive metal is applied to the upper layer of the substrate having the metal thin film obtained in this manner, with a film thickness of 1 to 4.
50 μm, preferably 2 to 10 μm, is applied, and the coating film is cured by irradiating ultraviolet rays to obtain a target transparent conductive film.
The conductive coating applied and cured on the upper layer becomes a hard coat film, and has a remarkable effect on protecting the lower metal film and improving the scratch resistance of the film surface. In addition, the superior conductivity of the lower layer is transmitted via the upper conductive film, and the conductivity is much better than when only the upper conductive paint is directly applied to the film and cured, and the conductivity is improved. effective.

[0017]

The present invention will be described more specifically with reference to the following examples. Hereinafter, parts are by weight unless otherwise specified.

Example 1 A 100 μm thick polyester film was set in a DC magnetron sputtering apparatus and set to 4 × 10 ⁻⁶ Torr.
And then a mixed gas of argon and oxygen (volume ratio
Ar: O ₂ = 90: 10) was introduced to reduce the degree of vacuum to 5 × 10
^-4 Torr. Keep the film temperature at 50 ° C,
DC sputtering was performed using an ITO (indium to tin ratio: 9: 1) target. The film thickness was 110 nm, and the surface resistivity was 80 Ω / □. Subsequently, using a wire bar, the following conductive paint was applied onto the film so as to have a dry weight of 8 g / m ² , and the solvent was volatilized and dried with hot air at 80 ° C.
The coating was cured by irradiating for 2 seconds to obtain the desired transparent conductive film. The resulting transparent conductive film has a visible light transmittance of 87%, a haze (haze value) of 1.0 and a surface resistivity of 11
It was 0 Ω / □. The pencil hardness of the film surface is 3H 3
At / 5, the hardness was excellent. [Preparation of conductive paint] 64 parts of dipentaerythritol hexaacrylate (KAYARAD DPHA (manufactured by Nippon Kayaku Co., Ltd.)), Irgacure 18 photopolymerization initiator
4 (manufactured by Ciba Geigy) 5 parts, Silicon slip agent SF-8421 (manufactured by Dow Corning Toray) 0.5
Parts, 30 parts of toluene and 6 parts of a dispersant (polyoxypolypropoxyalkylamine) were mixed and dissolved, and furthermore, ITO having an average particle diameter of 20 nm (the ratio of indium to tin was 9: 1) 5
180 parts of a toluene solution in which 4 parts were dispersed were gradually added to obtain a conductive paint.

Example 2 After sputtering ITO in the same manner as in Example 1, the following conductive paint was applied to a dry weight of 7 g / m ² ,
After evaporating and drying the solvent with hot air of 80 ° C, high-pressure mercury lamp 120W
UV light was applied for 4 seconds to cure the coating film to obtain the desired transparent conductive film. The visible light transmittance of the obtained transparent conductive film was 86%, the haze (haze value) was 1.2, and the surface resistivity was 120 Ω / □. The pencil hardness of the film surface was 3/5 for 3H, indicating excellent hardness. [Preparation of conductive paint] 64 parts of dipentaerythritol hexaacrylate (KAYARAD DPHA (manufactured by Nippon Kayaku Co., Ltd.)), Irgacure 18 photopolymerization initiator
4 (manufactured by Ciba Geigy) 5 parts, Silicon slip agent SF-8421 (manufactured by Dow Corning Toray) 0.5
, 30 parts of toluene and 6 parts of a dispersant (polyoxypolypropoxyalkylamine) were mixed and dissolved, and 54 parts of zinc antimonate having an average particle diameter of 30 nm (the ratio of antimony to zinc was 8: 2) was further dispersed. 180 parts of a mixed solution of methanol and isopropyl alcohol (the ratio of methanol to isopropyl alcohol was 3: 7) was gradually added to obtain a conductive paint.

Example 3 A polyester film having a thickness of 188 μm was set in a DC magnetron sputtering apparatus and set to 4 × 10 ^-6 Torr.
And then a mixed gas of argon and oxygen (volume ratio
Ar: O ₂ = 90: 10) was introduced to reduce the degree of vacuum to 5 × 10
^-4 Torr. Keep the film temperature at 50 ° C,
DC sputtering was performed using an ATO (antimony to tin ratio: 5:95) target. The film thickness is 100 nm
And the surface resistivity was 80 Ω / □. Subsequently, using a wire bar, the same conductive paint as in Example 2 was applied on this film so as to have a dry weight of 8 g / m ^2.
After the solvent was volatilized and dried with hot air at 0 ° C., the coating was cured by irradiating ultraviolet rays from a high-pressure mercury lamp 120 W for 4 seconds to obtain a target transparent conductive film. The visible light transmittance of the obtained transparent conductive film was 84%, the haze (haze value) was 1.3, and the surface resistivity was 130 Ω / □. The pencil hardness of the film surface was 3/5 for 3H, indicating excellent hardness.

Example 4 A film in which a silver thin film was laminated was obtained in the same manner as in Example 3 except that the target metal at the time of sputtering was changed to silver. The silver film thickness was 75 nm, and the surface resistivity was 80 Ω / □. The conductive paint used in Example 1 was applied and cured on the film in the same manner as in Example 1 to obtain a target transparent conductive film. The resulting transparent conductive film had a visible light transmittance of 82%, a haze (haze value) of 1.4, and a surface resistivity of 90Ω / □.

Comparative Example 1 In Example 1, the sputtering of ITO was not performed.
Except that the conductive paint of Example 1 was applied directly on a 100 μm polyester film, it was cured by irradiation with ultraviolet rays in the same manner as in Example 1 to obtain a hard-coated transparent conductive film. The resulting conductive film had a visible light transmittance of 89% and a haze of 0.9 and was transparent. In addition, the pencil hardness was 3/5 of 3H, and the hardness was excellent. But surface resistivity 8 × 10 ⁷ Ω / □ and is, had low remarkable conductivity as compared with Example 1.

Comparative Example 2 In Example 2, the sputtering of ITO was not performed.
Except that the conductive paint of Example 2 was applied directly on a 100 μm polyester film, it was cured by irradiation with ultraviolet rays in the same manner as in Example 2 to obtain a hard-coated transparent conductive film. The resulting conductive film had a visible light transmittance of 89% and a haze of 1.1 and was transparent. In addition, the pencil hardness was 3/5 of 3H, and the hardness was excellent. However, the surface resistivity was 5 × 10 ⁸ Ω / □, and the conductivity was remarkably lower than that of Example 2.

Comparative Example 3 In Example 1, only the sputtering of Example 1 was performed, and a transparent conductive film was obtained without applying a conductive paint to the upper layer. Although the surface resistivity was 75 Ω / □ and the conductivity was good, the pencil hardness was 1/5 at 3B and the film was very easily damaged.

[0025]

As described above, a hard coat film having excellent transparency and conductivity was obtained. Since the cured product of the ultraviolet curable resin used in the present invention has a high hardness, it is characterized in that the surface of the film is hardly damaged, and that the weather resistance, the solvent resistance and the durability are remarkably excellent.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B05D 5/12 B05D 5/12 B 7/24 301 7/24 301T 302 302P 303 303C B32B 7/02 104 B32B 7/02 104 9/00 9 / 00 A C09D 4/02 C09D 4/02 5/24 5/24 // C08J 7/04 C08J 7/04 D L

Claims (3)

[Claims] A conductive metal thin film layer is provided on a transparent substrate made of a polymer, and further, conductive metal fine particles having a particle size of 0.5 μm or less are dispersed in an ultraviolet curable resin. A transparent conductive film provided with a cured coating layer of paint. 2. The film according to claim 1, wherein the conductive metal is ITO (tin-doped indium oxide), ATO (antimony-doped tin oxide), zinc antimonate or silver. 3. The film according to claim 1, wherein the ultraviolet-curable resin is mainly composed of a polyfunctional acrylate having two or more acryloyl groups in a molecule.