JPH0348605B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a transparent conductive film circuit board with excellent scratch resistance, 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 for transparent electrodes in electroluminescent displays and electromic displays, day frosters, surface heating elements such as transparent heaters, surface switches such as touch panels, infrared reflective films,
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 have the advantage of allowing devices to be made thinner by using film-shaped circuit board electrodes.
It is attracting attention because it is easy to handle in the production process, it can be punched out, etc., it can be continuously produced from a film-like material, and it is advantageous in terms of cost.

As the uses of transparent conductive films have expanded, the performance requirements have also become more severe.

Scratch resistance is very important, especially for use in touch panels and the like.

In order to improve the scratch resistance, a method is proposed in which semi-inorganic polymers (silicon resins, etc.), organic compounds, etc. are formed on the film base material, and a conductive layer is further formed thereon (Japanese Unexamined Patent Publication No. 56-10450). Although attempts have been made to provide a hard organic compound or organic compound layer as a protective layer on a conductive film, it is common practice to process a transparent conductive film into a pattern before using it as a circuit board. It is.

However, in the case of a top coat using such an insulator, when the thickness of the top coat layer exceeds a certain value, the contact resistance increases rapidly and the top coat no longer functions as a circuit board electrode.

On the other hand, it goes without saying that in order to improve the scratch resistance, the top coat layer should be thicker.

Therefore, the present applicants completely changed the conventional idea and focused on applying a conductive paint as a top coat layer.

[Purpose of the Invention] The present invention was developed as a result of research aimed at obtaining a transparent conductive film with excellent abrasion resistance and transparency, which could not be obtained using conventional methods. It was discovered that a transparent conductive film that satisfies all required performances could be obtained by top-coating the film, and based on this knowledge, various studies were carried out 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 by top coating with a transparent paint having conductivity.

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 polyester resins such as polyimide, polyamideimide, polyamide, polysulfone, polyethersulfone, and polyetherketone. Examples include aromatic polyamide resins.

Of course, these may be used alone or as a blend as homopolymers or copolymers.

Metals and/metal oxides that are conductive film materials include gold, silver, zirconium, indium,
Tin, titanium, etc. or tin oxide, indium oxide, tin-cadmium oxide, etc. can be used.

Naturally, in order to apply the conductive film to the polymer film, there is no problem in applying the conductive film by a physical deposition method such as vacuum evaporation method or sputtering method, or a chemical deposition method such as chemical plating method or vapor phase method. There isn't.

Furthermore, when applying these conductive films to a polymer film, there is no problem even if a third layer is formed between the polymer film and the conductive film in order to improve the adhesion, etc. Rather, it is desirable to increase the adhesion between the polymer film and the conductive film in order to improve the flexibility and processability of the transparent conductive film.

A conductive film is applied to the polymer film and then top coated.

The transparent conductive paint used as the top coat is
As the filler, a conductive material such as metal and/or metal oxide such as gold, silver, zirconium, indium, tin, titanium, etc., or powder of tin oxide, indium oxide, tin-cadmium oxide, etc. is used.

As a binder for the transparent conductive paint, a thermoplastic resin such as an acrylic resin, a styrene resin, or a vinyl acetate resin may be used, or a thermosetting resin such as an epoxy resin or a phenolic resin may be used.

Of course, these may be used as homopolymers or copolymers.

This conductive paint is coated on the conductive film.

This can be done either before or after patterning the conductive film.

Incidentally, there are commercially available conductive paints such as Shintron from Shinto Paint Co., Ltd., but the thickness
When coated with a thickness of 2 μm, the surface resistance value is 10 ⁵
Ω/□, visible light transmittance of 85%, but the surface resistance value is preferably 10 ³ Ω/□ or less for use as an electrode for touch ^panels , etc.
It is difficult to use these commercially available conductive paints alone as electrodes because it is necessary that the resistance is Ω/□ or less.

On the other hand, conductive thin films made by vacuum evaporation, ion plating, and sputtering are transparent and
Although it has very good conductivity, it has a drawback that it has poor scratch resistance and cannot be used as electrodes for touch panels.

It is possible to obtain a laminated conductive film which overcomes these drawbacks and has excellent scratch resistance, transparency and conductivity, which were hitherto unimaginable.

[Effects of the Invention] The present invention coats a conductive film with a transparent conductive paint, and can provide a sufficiently thick protective layer compared to a top coat using an insulating material. This is an extremely excellent film that provides a transparent conductive film with excellent abrasion resistance and high transparency.

[Example] Example Using a polyether sulfone film as a substrate, a transparent conductive film containing indium as a main component was formed to a thickness of 300 mm by vacuum evaporation.

This transparent conductive film was patterned and coated with conductive paint (Cintron C-4423, manufactured by Shinto Paint Co., Ltd.) to a thickness of 2 μm.

The transparent conductive film thus produced had a sheet resistance of 310Ω/□ and a visible light transmittance of 81%.

In addition, no change in resistance value was observed even after rubbing 100,000 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, but no top coat was formed.

Sheet resistance value is 300Ω/□, visible light transmittance is
It was 83%.

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

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

Claims (1)

[Claims] 1 Forming a thin film of metal and/or metal oxide as a conductive layer on a polymer film by vacuum evaporation, ion plating, or sputtering, and further forming a conductive paint as a top coat layer. A method for manufacturing a transparent conductive film.