JPH0112664B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a transparent conductive film using polyether sulfone or polysulfone film obtained by melt extrusion method,
More specifically, a coating solution containing a silane coupling agent having an ethylenic double bond, a polyfunctional vinyl compound, a photosensitizer, and a solvent as main components is applied to at least one side of the film, and after drying, the film is exposed to ultraviolet rays. The present invention relates to a method for manufacturing a transparent conductive film by forming a transparent conductive layer on the cured material layer after reaction curing. In recent years, there has been a remarkable growth in display elements using liquid crystals, and for this reason, the importance of transparent electrodes is increasing. The electrodes conventionally used in liquid crystal display elements are
A method has been widely used in which so-called Nesa glass, which is a thin glass plate on which a conductive thin film is formed, is used, and electrode circuits are formed by etching the conductive thin film. However, as the device becomes thinner,
In response to demands for weight reduction and mass production, transparent electrodes in which a conductive thin film is formed on a transparent polymer film have been widely studied, and some have begun to be put into practical use. On the other hand, although transparent conductive films made from polymer films are superior in terms of thinness, weight reduction, mass production, and high strength, there are problems when forming a conductive layer directly on the film compared to glass. It is also true that there are points. That is, B. The abrasion resistance of the conductive thin film during the rubbing process of the electrode surface for the purpose of alignment treatment of liquid crystal is poor and the surface resistance increases. ○B A transparent conductive film using a uniaxially oriented polyester film is a polymer film that has been put into practical use or is close to being put into practical use, but in addition to its poor heat resistance, the optical axis is a polarizing film because the support has optical anisotropy. It is very difficult to match the axis exactly. It is also difficult to obtain a film that is aligned in the axial direction. ○C A so-called cast film can be considered as a non-optically active film, but it is extremely low in productivity. ○D Poor adhesion with the conductive layer thin film, poor humidity and heat resistance reliability, and wire breakage is likely to occur during circuit processing. etc. In order to eliminate these drawbacks, the present inventors investigated various polymer films, and found that polyether sulfone and polysulfone films, which are heat-resistant, non-optically active films and can be obtained by extrusion and have good transparency, have been developed. I found something good and chose it. However, if a conductive thin film is simply formed on polyether sulfone or polysulfone film, the adhesion between the thin film and the film is significantly poor, and the moisture resistance of the conductivity deteriorates significantly, making it unusable. It has disadvantages such as poor wear resistance and easy disconnection, and poor bendability and easy disconnection when processing circuits and assembling elements. The present inventors attempted vinyl silane and acrylic silane treatment using conventional methods as a method to eliminate these defects caused by adhesion. As a result, it has been found that the adhesion to the conductive film formed by the sputtering method is significantly improved. However, since these compounds are monofunctional monomers, when attempting to polymerize and fix them through treatments such as heating, only a so-called thermoplastic resin with a linear structure can be obtained, so the treated film must be a film with a low melting point. However, we have discovered a phenomenon in which the conductive film layer is unstable and deformed during thermal processes such as sputtering and heat treatment of the rubbing agent, causing minute wrinkles in the conductive film layer and causing minute cracks. The inventors of the present application have conducted intensive studies to overcome this phenomenon and its drawbacks, and have arrived at the present invention. That is, a method has been discovered in which the coating film itself is three-dimensionally crosslinked to form a stable coating film that is difficult to deform. The details of the present invention will be described below. The film used in the present invention is a polyethersulfone (hereinafter referred to as PES film) or polysulfone (hereinafter referred to as PS film) film obtained by melt extrusion method, and the film has excellent heat resistance and transparency. This is an extremely excellent film for transparent electrodes without optical rotation. Next, adjust the coating liquid to be applied onto the PES film or PS film. First, as a coupling agent, all so-called vinyl silane coupling agents having an ethylenic carbon-carbon double bond in the molecule such as vinyl silane and/or acrylic silane can be used, and solutions of these coupling agents can also be used as appropriate. It is. Next, a polyfunctional vinyl compound having two or more ethylenic double bonds is added to the coupling agent. Examples of these compounds include epoxy diacrylate, urethane diacrylate, polyester diacrylate, trimethylolpropane triacrylate, and polyethylene glycol diacrylate. polyfunctional acrylates such as butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, hexanediol dimethacrylate, trimethylolpropane trimethacrylate, polyfunctional methacrylates such as diallyl phthalate, triaryl isocyanurate, triaryl trimellitate, etc. Functional aryl compounds, etc. are used as appropriate. Furthermore, the blending ratio of the polyfunctional vinyl compound to the silane coupling agent having ethylenic double bonds is important;
It is blended in a range of ~100 parts by weight. If the amount is less than 10 parts by weight, the coating film becomes thermally soft and no improvement effect is exhibited, while if it is more than 100 parts by weight, the adhesion to the conductive film decreases and the effect of the coupling agent is halved. Next, a photosensitizer is added, and general photosensitizers such as benzophenone, benzoin methyl ether, and benzoin ethyl ether are used alone or in combination. The mixture thus obtained is then diluted with a solvent; in this case, a solvent that is a good solvent for the formulation, a poor solvent for PES films and PS films, and has an affinity for the mixture must be selected. This is important, and as such solvents, solvents belonging to cellosolves and carbitols are preferably used. Also, adding a small amount of a good solvent to the PES film is also an effective means for achieving uniform coating. Further, the dilution rate is appropriately determined from the viewpoints of coating thickness and coating workability. Further, addition of coloring inhibitors, leveling agents, antifoaming agents, bluing agents, wetting improvers, etc. is also an effective means for achieving the present invention. The coating liquid thus obtained is applied to at least one side of the PES film by a conventional method such as a dip method, a bar coater method, a roll coater method, a spray method, or a spin coat method. It is desirable that the coating thickness be as thin as possible with the premise of uniform coating.
A thickness of around 5 μm is common for this purpose. Next, the solvent is removed by drying to form a coating film, and the coating surface is then irradiated with ultraviolet rays to form a crosslinked cured coating film. A transparent conductive layer is then formed on the resulting film coating. In this case, oxides such as indium oxide, tin oxide, cadmium oxide, etc. are used alone or in combination and are formed by a sputtering method or an ion plating method. The transparent conductive film obtained in this way has excellent abrasion resistance, circuit processability, moisture resistance, and solvent resistance because the conductive layer is firmly integrated with the support layer, and unlike the case where a coupling agent is used alone, it is strong. Because a three-dimensional crosslinked coating film is formed, this transparent conductive film has excellent heat resistance and is of great industrial significance. Examples are shown below. Example γ-Methacryloxypropyltrimethoxysilane 100 parts by weight Trimethylolpropane triacrylate
30 parts by weight neopentyl glycol diacrylate
20 parts by weight Benzoin isobutyl ether 5 parts by weight Butyl cellosolve 500 parts by weight The above compositions were mixed at room temperature to obtain a homogeneous solution. The above solution was applied uniformly onto one side of a 100 μm thick PES film using a roll coater method, heated at 80°C to remove the solvent, and then irradiated with a single 80 W/cm high pressure mercury lamp at an irradiation distance of 15 cm for 10 seconds. did. The thickness of the obtained cured coating film was 5 μm. A transparent conductive layer of indium oxide and tin oxide was formed on this coating film to a thickness of 300 Å by a sputtering method. Various properties of the obtained transparent conductive film are shown in Table 1. Comparative Example 1 100 parts by weight of γ-methacryloxypropyltrimethoxysilane 3 parts by weight of benzoin isobutyl ether After the above composition was mixed uniformly at room temperature, the composition was coated on one side of a 100 μm thick PES film using a roll coater method. A coating layer with a thickness of 3 μm was provided by uniform application. The coating layer was cured by ultraviolet irradiation under the same conditions as in the examples, and a transparent conductive layer was formed on the coating layer by sputtering. Various properties of the obtained transparent conductive film are shown in Table 1. Comparative Example 2 γ-methacryloxypropyltrimethoxysilane 10 parts by weight Methyl methacrylate 30 parts by weight 2-hydroxyethyl methacrylate 20 parts by weight Trimethylolpropane triacrylate
30 parts by weight neopentyl glycol diacrylate
10 parts by weight Benzoin isobutyl ether 3 parts by weight Butyl cellosolve 350 parts by weight The above compositions were mixed at room temperature to obtain a homogeneous solution. After applying the composition uniformly onto one side of a 100μ thick PES film using a roll coater method,
When the solvent was removed by heating at °C, a coating layer with a thickness of 4 μm was obtained. The coating layer was cured by ultraviolet irradiation and a transparent conductive layer was formed on the coating layer by sputtering under the same conditions as in the examples. Various properties of the obtained transparent conductive film are shown in Table 1.

【table】

[Table] As described above, although the transparent conductive film obtained in Comparative Example 1 had good adhesion between the coating layer and the conductive layer, it was significantly inferior in heat resistance and solvent resistance. Although the transparent conductive film obtained in Comparative Example 2 has good heat resistance and solvent resistance, it has poor moisture resistance and abrasion resistance due to poor adhesion between the coating layer and the conductive layer. decreased. On the contrary, the transparent conductive films obtained in the Examples of the present invention had excellent properties that eliminated all of the above-mentioned drawbacks.

Claims (1)

[Claims] 1. A silane coupling agent having an ethylenic double bond in the molecule on at least one side of a non-optically active film of polyethersulfone or polysulfone obtained by a melt extrusion method. A coating solution containing 10 to 100 parts by weight of a polyfunctional vinyl compound having
The following coating film is applied, dried at a temperature of 100°C or less, then cured by irradiation with ultraviolet rays, and a conductive thin film mainly composed of indium oxide is formed on the coating film by vapor deposition or sputtering. A method for producing a transparent conductive film, characterized by: