JPS6332620B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a transparent conductive film for use in transparent electrodes for liquid crystal display devices, in which a conductive film containing a metal and/or metal oxide as a main component is applied to a polymer. This relates to a manufacturing method.

[Prior art]

Conventionally, transparent conductive films are mainly based on polyester films, and are used in transparent electrodes of electroluminescent displays and electrochromic displays, surface heating elements such as day frosters and transparent heaters, surface switches such as touch panels, infrared reflective films, and It has been widely used in transparent flexible circuits and the like, but recently its application to liquid crystal display elements is also being considered.

Transparent conductive films can be made thinner by using film-shaped electrodes, are easy to handle during the production process and can be punched out, and can be manufactured continuously from film-shaped materials, making them cost-effective. It is attracting more attention than because it is advantageous.

Ordinary transparent conductive films are required to have excellent transparency and conductivity, and are also required to have alkali resistance and abrasion resistance in terms of processability.
Alkali resistance is necessary to prevent poor conductivity or disconnection from occurring due to the alkaline aqueous solution used in the resist stripping process in the patterning process of transparent conductive films, and scratch resistance is necessary to prevent poor conductivity from occurring during handling during the processing process. This is required to prevent wire breakage from occurring.

However, in the vacuum evaporation method, ion plating method, and sputtering method, which are the usual conductive film formation methods, rapid heat release occurs due to the phase transition from gas phase to solid phase during formation of the conductive film, which causes strong internal stress in the conductive film itself. It takes.

Furthermore, disturbances in the crystal lattice and pinholes of the conductive film cannot be avoided, and these significantly deteriorate alkali resistance and scratch resistance. Regarding this point, attempts have been made to improve this by further applying a top coat on the conductive film. However, the top coat produced by the conventional method has large thickness variations and many pinholes, resulting in non-uniform conductivity, and has serious drawbacks such as non-uniform etching time due to variations in the top coat thickness during the etching process. I had it with me.

[Purpose of the invention]

The present invention was developed as a result of research aimed at obtaining a transparent conductive film that has excellent alkali resistance and abrasion resistance, which could not be obtained using conventional coating methods, and that does not cause non-uniformity in conductivity, etching time, etc. It was discovered that a transparent conductive film that satisfies all required properties could be obtained by applying the film as a top coat, and based on this knowledge, various studies were conducted and the present invention was completed.

[Structure of the invention]

The present invention is a method for producing a transparent conductive film, which is characterized in that the surface of the conductive film is top coated by plasma polymerization.

The polymer film used in the present invention can be produced by vacuum deposition,
Heat-resistant polymer films are used to form conductive films by ion plating or sputtering methods, and include polyimide, polyamideimide, polyamide, polysulfone, polyethersulfone,
Examples include polyester-based resins, aromatic polyamide-based resins, etc., including polyetherketone.
Of course, these may be used alone or as a blend as homopolymers or copolymers.

Further, as the metal and/or metal oxide that is the conductive film material, gold, silver, zirconium, indium, tin, titanium, etc., or tin oxide, indium oxide, tin-cadmium oxide, etc. can be used. .

Of course, in order to apply the conductive film to the polymer film, it is possible to apply the conductive film by physical deposition methods such as vapor deposition or sputtering, or by chemical deposition methods such as chemical plating or vapor phase plating. There's nothing wrong with that.

Furthermore, when applying these conductive films to a polymer film, there is no difference even if a third layer is formed between the polymer film and the conductive film in order to improve the adhesion, etc. There is no problem, but if you want to improve the adhesion between the polymer film and the conductive film,
This is desirable in order to improve the flexibility and processability of the transparent conductive film.

A polymer film with a conductive film added to it,
Top coating is performed on the conductive film using a plasma method.

In plasma polymerization, an organic monomer with a simple structure is introduced into a plasma space, and radical species generated in the gas phase are polymerized and deposited on the conductive film to form a thin film as a protective layer. The organic monomer may be any substance, including those that polymerize with ordinary catalysts or light, such as olefins such as styrene, methyl methacrylate, acrylonitrile, ethylene, and propylene; There may be one or a combination of two or more. Furthermore, in the plasma treatment, even if the organic monomer is used alone, an inert gas such as argon may be used as a carrier gas for the organic monomer.

In selecting an organic monomer, in the present invention, it is necessary to select an organic monomer that is weak against acids and strong against alkalinity for the purpose of improving alkali resistance. The plasma polymerized film thus produced is a highly crosslinked, homogeneous thin film without pinholes, and is extremely suitable as a top coat for transparent conductive films.

〔Effect of the invention〕

By top-coating a homogeneous thin film without pinholes, which is a characteristic of a plasma polymerized film, the present invention provides a transparent conductive film that has excellent alkali resistance and abrasion resistance, as well as high transparency and high conductivity, which were previously unobtainable. It is an industrially excellent product. Furthermore, since there is no unevenness in the coating thickness, it is an excellent method for producing a transparent conductive film that is easy to pattern.

〔Example〕

Using a polyether sulfone film as a substrate, a conductive film containing indium as a main component was formed to a thickness of 300 Å using a vacuum evaporation method. A styrene plasma polymerized film was formed on this. Discharge frequency 5KHz discharge power
Plasma polymerization was performed at 8W pressure of 1 Torr for 1 minute. The film thickness was 400 Å. The transparent conductive film produced in this way has a sheet resistance of 320Ω/□, a visible light transmittance of 85%, and a sheet resistance value that changes rapidly at 320Ω/□ after being immersed in a 10% potassium hydroxide aqueous solution for 10 minutes. I didn't. Even after this film was immersed in an aqueous potassium hydroxide solution and magnified 300 times with an optical microscope, no cracks were clearly visible.

Furthermore, no change in resistance value was observed even after rubbing 5,000 times with gauze under a load of 100 g/cm ² .

[Comparative example]

A conductive film was formed under the same conditions as in the example, and no plasma polymerized film was formed. The sheet resistance value is
It was 300Ω/□, and the visible light transmittance was 83%. This was immersed in an aqueous potassium hydroxide solution under the same conditions as in the example. The sheet resistance value was 500Ω/□, and when observed under 300x magnification with an optical microscope, many cracks were observed.

Also, when rubbed 5,000 times with gauze with a load of 100g/ ^cm2 , the sheet resistance becomes 10KΩ/□,
Scratch resistance was poor.

For the above reasons, the transparent conductive film of the present invention is excellent.

Claims (1)

[Claims] 1 A thin film of metal and/or metal oxide is formed as a conductive layer on a polymer film by vacuum evaporation, ion plating, or sputtering, and a top coat layer is further formed by plasma polymerization. A method for producing a transparent conductive film.