JP3040693B2 - Transparent conductive laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to films for electronic devices such as EL devices and LCD devices, and more particularly to an electrode substrate for manufacturing a liquid crystal cell.

[0002]

2. Description of the Related Art As a transparent conductor, a material in which a tin oxide or indium oxide film is formed on a glass substrate has been known for a long time. Today, it is widely used for electrodes of various liquid crystal displays and transparent surface heating elements. Have been. On the other hand, a transparent conductive film is obtained by replacing a conventional glass substrate with a polymer film, and is thin, lightweight, flexible without cracking, has good workability, and has a large area. And is promising especially as an electrode material for liquid crystal. In JP-A-61-86252, an anchor coat layer using a urethane-based resin is provided on one side of a PES film, and a polyvinyl alcohol-based resin is further laminated as a gas barrier layer. A transparent laminated conductive film for liquid crystal in which an ultraviolet curable resin is formed, an acrylic ultraviolet curable resin is provided on the other surface of the PES film, and a conductive layer mainly containing indium oxide is further provided thereon. Is disclosed.

When the above-mentioned film substrate is used for a liquid crystal application, it must be provided with a function of preventing the transmission of air from the film side. When air passes through, bubbles are generated in the liquid crystal, which is a fatal obstacle in appearance. Therefore, in order to convert a glass substrate into a polymer film, it cannot be used for liquid crystal applications unless air transmission is prevented. Here, as a prevention method, a base film capable of trapping air may be used. However, the most preferable condition for use in a liquid crystal or the like is a birefringence having a phase difference within 40 degrees and a photoelastic constant of 2.0 mm. / Kg or less, PES is an amorphous polymer to satisfy high heat resistance
It cannot be achieved without film. However, the air permeability of these amorphous polymer films is generally large,
It is difficult to prevent liquid crystal deterioration, and a gas barrier layer is required on this base film. Examples of the organic material layer having the best gas barrier properties include polyvinyl alcohol resin, ethylene-vinyl alcohol copolymer, cellulose-based, polyacrylonitrile-based, polyvinylidene chloride-based, and polyamide-based resins. A polyvinyl alcohol resin which is strong and has a high functional group concentration is most preferable. However, since polyvinyl alcohol resin is highly hydrophilic, it adheres to water under high humidity and cuts hydrogen bonds, impairing the confidentiality of the structure and sharply lowering the gas barrier property. Also, when a resin other than polyvinyl alcohol is used, it is necessary to considerably increase the film thickness,
Problems arise in curl due to internal stress, heat resistance, and the like.

[0004]

SUMMARY OF THE INVENTION Under such a background, the present invention provides a transparent conductive material in which a polyvinyl alcohol resin and an ethylene-vinyl alcohol copolymer are laminated to improve the gas barrier property under high humidity. It is intended to provide a laminated film.

[0005]

According to the present invention, an organic resin gas barrier layer (3) is laminated on at least one surface of a polyether sulfone film (hereinafter abbreviated as PES film) (1) via an adhesive layer (2). Forming an epoxy thermosetting resin or an acrylic ultraviolet curing resin as a protective coating layer (4), and providing an acrylic ultraviolet curing resin as an undercoat layer (5) on the other side of the PES film; Further, a transparent conductive layer mainly composed of indium oxide (6)
Wherein the gas barrier layer comprises at least two layers of a polyvinyl alcohol resin (3a) and an ethylene-vinyl alcohol copolymer (3b) having an ethylene content of 20 to 50 mol%. A transparent conductive laminated film characterized by being laminated, wherein the outermost layer of the organic resin gas barrier layer (3) is an ethylene-vinyl alcohol copolymer (3b).

[0006] The PES film (1) in the present invention serves as a base material of a transparent conductive film, and has a mechanical strength,
This film must be this film in terms of optical characteristics, heat resistance and the like. The thickness of the film is 50 to 300 μm,
Preferably it is 75 to 125 μm. The adhesive layer (2) is obtained by applying a resin varnish and removing the solvent by drying. At this time, as the resin system, a resin system having a film forming property after removing the solvent, that is, a varnish to which a solid resin is added is preferable from the viewpoint of uniform coating, and specific examples thereof include urethane resins, and polyester and polyether types. However, the polyester type is generally preferred from the viewpoint of heat resistance and adhesiveness. As a method of forming the adhesive layer on the substrate, there are a gravure coating method, a reverse roll coating method, a kiss roll coating method and the like, and any method can be used to cure within 5 minutes in consideration of industrial production. Is desirable.

The gas barrier layer (3) has been intensively studied with an emphasis on obtaining sufficient gas barrier properties under high humidity, heat resistance and curl characteristics in a well-balanced manner. A good result was found by using together an ethylene-vinyl alcohol copolymer having a low humidity dependency similar to the above. In this case, the ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 50% is used. And, by adopting a configuration in which an ethylene-vinyl alcohol copolymer layer having a smaller hygroscopic property is laminated on the polyvinyl alcohol resin layer on the layer constitution, the gas barrier layer is less affected by humidity. . The gas barrier layer is preferably formed by the same method as in the case of the adhesive layer (2). In addition, this formed film must be substantially transparent and optically isotropic. The thickness of the barrier layer is not particularly limited. However, from the viewpoint of performance, if the thickness is too small, the performance as a barrier coat cannot be expected.
A thickness of at least μm is required. On the other hand, if the thickness exceeds 20 μm on one side, the stress is high, and problems such as curling occur.

Next, the protective coating layer (4) laminated on the above-mentioned gas barrier layer has an adhesion to the gas barrier layer other than hydrochloric acid resistance so as to withstand etching treatment of the conductive film.
Further, it is necessary that the drying and curing temperature is 170 ° C. or less, which is the discoloration start temperature of the polyvinyl alcohol resin, and that the film has excellent transparency and solvent resistance. As long as the above conditions are satisfied, either an organic substance or an inorganic substance may be used, but it is preferable to coat the organic substance in terms of cost, and specific examples thereof include an epoxy thermosetting resin and an acrylic ultraviolet curing resin. The method for forming the protective coat layer is also preferably the same as the method for forming the adhesive layer (2). In addition, this formed film must be substantially transparent and optically isotropic.

Next, before forming a film mainly containing indium oxide or the like as a conductive layer, an undercoat layer is formed on the PES film for the purpose of improving scratch resistance, alkali resistance and the like.
(5) is provided. The reason for this is that a transparent conductive film is formed by forming a conductive film on a polymer film by a vacuum evaporation method, an ion plating method, or a sputtering method. Is often used, but the film thickness is often reduced because high transparency is required in addition to conductivity. This is because, in the processing step of the transparent conductive film, abrasion resistance for preventing disconnection due to scratches and durability against alkali treatment in the pattern processing step are required. Specifically, an acrylic UV curable resin is most desirable, and the method for forming the layer is also preferably a film formation by the same method as in the case of the adhesive layer (2).

Finally, a transparent conductive layer (6) is formed on the coating. The transparent conductive layer is a thin film of a metal oxide, such as indium oxide, tin oxide, and cadmium oxide. Of these, it is particularly preferable to form a thin film of indium oxide containing 5 to 10% by weight of tin oxide. These film thicknesses can be appropriately selected in the range of 50 to 2000 °. These thin films are formed by a known method such as a sputtering method and an ion plating method. In this way, a transparent conductive film without a decrease in gas barrier properties even under high humidity was obtained.

[0011]

【Example】

<< Embodiment 1 >> FIG. 2 is a schematic view of a transparent conductive film of the present invention, in which a transparent conductive layer (6) is provided. The PES film (1) as a substrate is formed by a melt extrusion method. The thickness is 100 μm, the retardation value is 10 nm or less, and the visible light transmittance is 90%. A urethane-based resin [Takenate A-3, Takeda Pharmaceutical Co., Ltd.] was uniformly applied to one side of the substrate (1) to a thickness of 2 μm by a roll coater method. On this adhesive layer, a polyvinyl alcohol resin [Kuraray Poval # 117 Co., Ltd.] was applied to a thickness of 3 μm, and further an ethylene-vinyl alcohol copolymer was applied to a thickness of 12 μm. Then, an epoxy resin [a bisphenol A type epoxy resin using polythiol as a curing agent] was applied thereon as a protective coat to a thickness of 3 μm. Epoxy acrylate resin [Showa Polymer Co., Ltd. Lipoxy VR-60] as an undercoat of the conductive layer
Was applied on the other PES film surface to a thickness of 3 μm. FIG. 1 shows the physical properties of the obtained substrate. And
Further, a transparent conductive laminated film provided with indium oxide in a thickness of 250 mm by a sputtering method was prepared.

Comparative Example 1 The same operation as in Example 1 was performed except that the gas barrier layer provided on the adhesive layer was formed to a thickness of 15 μm using only polyvinyl alcohol resin. << Comparative Example 2 >> In Example 1, the gas barrier layer provided on the adhesive layer was made of ethylene-vinyl alcohol copolymer.
Exactly the same operation was performed except that a 2 μm thick coating was applied and a polyvinyl alcohol resin was formed thereon to a 3 μm thickness.

[0013]

According to the transparent conductive laminated film obtained by using this, a good liquid crystal display element which does not impair the gas barrier property even in a high humidity atmosphere could be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between relative humidity and oxygen permeation amount for Example 1 and Comparative Examples.

FIG. 2 is a cross-sectional view of the transparent conductive film of the present invention, showing a state where a transparent conductive layer (6) is laminated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PES film 2 Adhesive layer 3 Gas barrier layer 3a Polyvinyl alcohol resin 3b Ethylene-polyvinyl alcohol copolymer 4 Protective coat layer 5 Undercoat layer 6 Transparent conductive layer

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08J 7/04 CEZ C08J 7/04 CEZP G02F 1/1333 500 G02F 1/1333 500 H01B 5/14 H01B 5/14 A

Claims (1)

(57) [Claims] An organic resin gas barrier layer (3) is laminated on one side of a polyether sulfone film (1) via an adhesive layer (2), and an epoxy thermosetting resin is further formed as a protective coating layer (4). Alternatively, an acrylic UV curable resin is formed,
A transparent conductive plastic film in which an acrylic UV curable resin is provided as an undercoat layer (5) on the other surface of the PES film, and further a transparent conductive layer (6) containing indium oxide as a main component is provided. An organic resin gas barrier layer, wherein the gas barrier layer is formed by laminating at least two layers of a polyvinyl alcohol resin (3a) and an ethylene-vinyl alcohol copolymer (3b) having an ethylene content of 20 to 50 mol%.
The outermost layer of (3) is an ethylene-vinyl alcohol copolymer (3
b) A transparent conductive laminated film, which is characterized in that: