JPH0210526B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to polyether sulfon (hereinafter abbreviated as PES) or polysulfon (hereinafter abbreviated as PS).
The present invention relates to a method for producing a laminated transparent conductive film, in which a transparent substrate is used, an ultraviolet curable resin layer is formed on at least one side of the transparent substrate, and a thin film containing indium oxide as a main component is formed on the resin layer. Specifically, the objective is to obtain a coating film that improves the drawbacks of PES and PS films, and to form a conductive thin film thereon to obtain a transparent conductive film with excellent properties. In recent years, there has been a remarkable growth in display elements using liquid crystals, and the importance of transparent electrodes used therein is also increasing. Conventionally, so-called Nesa glass, in which a semiconductor thin film is formed on a thin glass plate, has been widely used as a transparent electrode for liquid crystal display elements, but as elements are required to be thinner, lighter, and mass-produced, Transparent electrodes formed with semiconductor thin films have been widely studied, and some have begun to be put into practical use. However, although conductive films using polymer films meet the demands of mass production due to thinness, weight reduction, continuous production, and punching capability, they also have various problems. It is. That is, (1) the abrasion resistance is poor and the surface resistance is poor in the rubbing process during the liquid crystal alignment process. (2) Polyester film is generally used as a polymer film support, but it has poor heat resistance. (3) Supports with high water vapor permeability have a negative effect on liquid crystals. (4) Some polymer supports may not be able to withstand processing such as thin film etching. (5) In the case of a support having optical anisotropy, the optical anisotropy axis must strictly coincide with the polarizing plate axis, resulting in poor workability. (6) Poor adhesion to the formed thin film. etc. In order to resolve problems (2) and (5) among these drawbacks, selection of the substrate film is important. The inventors of the present invention extensively studied various films and found that PES film or PS film, which has heat resistance, is transparent, and is optically isotropic, is superior. In addition, as a method for solving the problems in other items (1), (3), (4), and (6), a method has been proposed in which a so-called undercoat layer is provided between the semiconductor layer and the film support. As such an undercoat agent, thermosetting resins such as epoxy resins, melamine resins, alkyd melamine resins, and UV-curing resins prepared by diluting acrylic prepolymers with monomers have been proposed. However, PES film or PS film is
As is well known, undercoating of these films has not yet been successful due to poor solvent resistance and poor adhesion to coating resins. In other words, when a thermosetting resin is used as a coating material, it takes a long time to cure and a thin film must be formed, so the resin may become uncured due to scattering of the curing agent and crosslinking agent. There is also the inconvenience that the film becomes thinner, and there is a limit to how thin the film can be made. In addition, radiation-curable resin systems such as ultraviolet rays and electron beams have been proposed, but these do not solve the problems of coating, such as deterioration of the film due to diluted monomers and poor adhesion. In addition, when the film is made even thinner, there arises the problem that polymerization is inhibited due to the oxygen inhibition effect. The inventors of the present application have conducted intensive studies on a method of manufacturing transparent conductive films using PES films and PS films as supports using a coating method using a radiation-cured resin, and have arrived at the present invention. That is, on at least one side of PES and PS films,
After coating with a specific coating liquid, which is an important component of the present invention, and drying to form a tack-free transparent coating film at room temperature, the coating film is irradiated with radiation to harden it to form a transparent coating film. After the formation of indium oxide, a method was found to form a semiconductor thin film containing indium oxide as the main component. According to this method, all of the above problems are solved and an excellent industrially useful transparent conductive film can be obtained. The details of the present invention will be described below. The PES film and PS film used in the present invention can be any film obtained by conventional methods (extrusion method, calendar method, etc.), but films with a thickness of 20 to 100 μm are preferably used. . The coating solution used to achieve the present invention is a solution of an epoxy acrylate prepolymer and/or a urethane acrylate prepolymer to which a sensitizer is added, and the prepolymer preferably has a melting point of 50° C. or higher. The reason for this is that if the solvent has a melting point of 50°C or higher, it has the ability to form a good, uncured, tack-free film at room temperature when the solvent is removed. Because a film can be formed, pinholes and cissing are less likely to occur, and the dry material can be wound up into a roll once, and PES and PS are not exposed to liquid materials for a long time, making it easier to use the support film. This is due to the fact that there is little deterioration. It is also an effective method to add a coupling agent such as vinyl silane to the solution for the purpose of improving adhesion. Furthermore, the selection of a solvent in preparing the coating liquid is also an important component of the present invention from the viewpoint of preventing deterioration of the support film. That is, it is essential that the mixed solution is a mixed solvent of a solvent that is a good solvent and a solvent that is a poor solvent for the support film (PES, PS), and that the mixed solution is a good solvent for the prepolymer. It is desirable that the amount of good solvent is less than that of poor solvent. Particularly preferably, the mixing ratio of good solvent and poor solvent is
30/70 to 15/85, and if the amount of good solvent is higher than this
Deterioration during the coating process of PES or PS film becomes a problem. If the amount is less than this, the adhesion between the support film and the coating film will deteriorate. In extreme cases, using only a poor solvent will not bond at all. Acetone, methyl ethyl ketone, dimethyl formamide, cellosolve acetate, carbitol acetate, etc. are good solvents for epoxy acrylate prepolymers and urethane acrylate prepolymers, and are also good solvents for PS or PES films. can give. On the other hand, examples of solvents that are good solvents for the prepolymer and poor solvents for PES and PS films include cellosolves, carbitols, butyl acetate, xylene, and toluene. Furthermore, the quantitative relationship between the prepolymer and the mixed solvent can be adjusted as appropriate depending on the desired thickness of the coating film.
The normal coating thickness is 0.1 to 10 μm on a dry basis, and if it is thicker than this, problems may arise in the flexibility of the final film. Conventional coating methods such as a dip method, a bar coater method, a roll coater method, a spray method, and a curtain coater method are used as the coating method, but it is preferable to remove the solvent as soon as possible after coating. In addition, the temperature for solvent removal is preferably 100℃ or less.
If the temperature is higher than this, there is a fear that the sensitizer will scatter and the film may not be cured. In this way, a PES film or PS film with a uniform resin coating formed on at least one side is obtained, and this coating is completely tack-free at room temperature and is very convenient to handle. Next, the coating surface is irradiated with radiation (generally ultraviolet rays) to completely cure it. In this case, the dry paint film is irradiated, which is a fundamentally different method from conventional irradiation of liquid materials. That is, it is irradiation curing in a solid state, and even an extremely thin coating film is not susceptible to sensitizer scattering or oxygen inhibition effects. It is also an effective method to further heat-treat after irradiation curing to ensure completeness. A transparent semiconductor layer is then formed on the cured coating. So-called thin films mainly made of oxides such as indium oxide, tin oxide, cadmium oxide, etc. are generally used, and the film thickness is approximately 50 to 500 Å. Sputtering and ion plating are the preferred methods of formation. used. In this way, a transparent conductive film using a PES film or PS film as a support and having an undercoat layer on at least one side is obtained. This film is an industrially significant and excellent transparent conductive film having the following characteristics. Since the abrasion resistance of the conductive layer is greatly improved, deterioration of surface resistance during the rubbing process can be prevented. The reliability of the liquid crystal is improved because the water vapor permeability is reduced. Since the chemical resistance during etching processing is greatly improved, the circuit processing yield is greatly improved. Excellent adhesion between the metal oxide thin film and the undercoat layer. Examples are shown below. Example 1 100 parts by weight of epoxy acrylate prepolymer with a molecular weight of 1540 and a melting point of 70°C, 400 parts by weight of butyl acetate,
100 parts by weight of cellosolve acetate and 2 parts by weight of benzoin ethyl ether were stirred at 50°C to form a uniform solution. The obtained solution was applied to both sides of a 75 μm thick polyether sulfon film and dried at 85° C. to completely remove the solvent. As a result, a tack-free coating was formed at room temperature. Next, the coating film was irradiated with ultraviolet rays at a distance of 15 cm from a high-pressure mercury lamp of 80 W/cm to cure the resin layer. Next, a mixture of indium oxide and tin oxide was vapor-deposited on one side of this coated film while heating with an electron beam in a vacuum, and this was heat-treated in air at 180° C. for 1 hour to form a transparent conductive layer with a thickness of about 300 Å. The properties of this transparent conductive film are shown in Table 1. Comparative Example 1 A transparent conductive layer was provided on a 75 μm polyether sulfon film in exactly the same manner as in Example 1 without applying an undercoat. Table 1 shows the properties of this transparent conductive film. Comparative Example 2 A conductive film was produced in exactly the same manner as in Example 1 except that cellosolve acetate, a good solvent, was replaced with 100 parts by weight of butyl acetate. The properties of this conductive film are shown in Table 1. Comparative Example 3 When a film in Example 1 was coated by replacing all butyl acetate, which was a poor solvent, with cellosolve acetate, which was a good solvent, cracks appeared on the entire surface of the film and no coating could be formed. 【table】

Claims (1)

[Claims] 1. A manufacturing method for obtaining a laminated transparent conductive film by forming an ultraviolet curable resin layer on at least one side of a polyether sulfon or polysulfon film, and forming a thin film containing indium oxide as a main component on the coating film, The coating liquid applied to form the ultraviolet curable resin layer is a solution in which an epoxy acrylate prepolymer and/or a urethane acrylate prepolymer is dissolved together with a sensitizer, and the solvent constituting the solution is compatible with the film. It is a mixed solvent of a good solvent and a poor solvent, and further, both are good solvents for the prepolymer, and the mixing ratio of good solvent/poor solvent is 30/70 to 15/85. A method for producing a transparent conductive film.