JPH1012394A - Transparent conductive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a transparent conductive sheet excellent in transparency, antistatic property, and electromagnetic shielding property by successively laminating a metal thin film having transparency and a transparent antistatic layer on a transparent synthetic resin sheet surface. SOLUTION: Silver is sputtered on the surface of a transparent synthetic resin sheet (polyvinyl chloride, polymethyl methacrylate, or the like) to form a metal thin film having transparency about 5-20nm in thickness. The surface resistance value of the metal thin film is preferably set to about 10Ω/(square) or less. A transparent antistatic layer formed of a conductive fine particle (antimony-contained tin oxide or the like) containing tin oxide and a resin binder is laminated on the metal thin film surface as a protecting layer. Thus, a transparent conductive sheet suitable for a display of computer, a cover for semiconductor manufacturing device, or the like can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive sheet excellent in transparency, antistatic property and electromagnetic wave shielding property.

[0002]

2. Description of the Related Art It is desirable that a display of a computer or a cover of a device used in a semiconductor manufacturing plant has transparency, antistatic property and electromagnetic wave shielding property.
A conventional resin plate with electromagnetic shielding properties
Japanese Patent Application Laid-Open No. 2-73599 describes a structure in which a conductive woven or nonwoven fabric is embedded in a plate-shaped base made of a transparent synthetic resin.

Further, Japanese Patent Application Laid-Open No. Hei 5-165373 discloses a laminate obtained by applying a photocurable antistatic paint to such a laminate.

[0004] For applications requiring transparency and sharpness of a see-through image, such as a cover for a computer display, the above-mentioned Japanese Utility Model Application Laid-open No. Sho 62-73599 and Japanese Patent Application Laid-Open No. H05-73590 have been proposed.
No. 165373 discloses insufficient transparency.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a transparent conductive sheet excellent in transparency, antistatic property and electromagnetic wave shielding property.

[0006]

The transparent conductive sheet of the present invention comprises a transparent synthetic resin sheet having a transparent metal thin film formed thereon and a transparent antistatic layer laminated on the surface of the metal thin film. It is characterized by the following.

In the present invention, the transparent synthetic resin sheet is a plate or a film made of a synthetic resin such as polyvinyl chloride, polycarbonate, polymethyl methacrylate, ABS, polyethylene terephthalate and the like.

As the metal thin film, gold, silver, platinum, palladium, aluminum, copper, nickel and the like, and alloys thereof are used. These metals are formed on a synthetic resin sheet by means such as sputtering or vacuum evaporation, and are very thin films themselves and therefore have transparency. If the thickness of the metal thin film is too small, the conductivity tends to be insufficient, and if the thickness is too large, the transparency is reduced, so the range of 5 to 20 nm is preferable. Further, in order to satisfy the electromagnetic wave shielding performance, the surface resistance of the metal thin film is preferably 10Ω / □ or less.

With the above structure, a conductive sheet satisfying transparency, antistatic property and electromagnetic wave shielding property can be obtained. However, since the metal thin film is extremely thin, the metal thin film is easily damaged in actual use, , The electromagnetic wave shielding property is extremely reduced. Therefore, it is necessary to provide a protective layer so as not to damage the metal thin film. By providing a transparent antistatic layer made of conductive fine particles containing tin oxide as a component and a resin binder as the protective layer, the metal thin film can be protected without deteriorating its performance.

As the conductive fine particles containing tin oxide as a component, fine powders such as antimony-containing tin oxide, indium tin oxide, and barium sulfate coated on the surface with antimony-containing tin oxide are used. The conductive fine particles are dispersed in an organic solvent together with a resin binder and applied and dried on a metal thin film to form an antistatic layer.

As the resin binder, a thermoplastic resin,
Thermosetting resin and photo-curing resin can be used.However, when using a thermoplastic resin, the protective effect on a metal thin film is inferior, but when grounding for electromagnetic wave shielding, the protective film on the surface can be easily formed with an organic solvent. Excellent workability because it can be removed. When a thermosetting resin or a photocurable resin is used, they are excellent as a protective layer, but are inferior in workability and are hardly grounded. Therefore, consideration must be given to selecting the resin of the resin binder according to the application.

(Function) In the transparent conductive sheet of the present invention, a transparent metal thin film is formed on the surface of a transparent synthetic resin sheet, and a transparent antistatic layer is laminated on the surface of the metal thin film. It has excellent properties, antistatic properties and electromagnetic wave shielding properties. Further, by providing a transparent antistatic layer comprising conductive fine particles containing tin oxide as a component and a resin binder, the metal thin film is protected without deteriorating its performance.

[0013]

Embodiments of the present invention will be described below. Example 1 A metal thin film was formed by sputtering silver on the surface of a polyvinyl chloride plate having a thickness of 3 mm. The surface resistance value of this metal thin film was 8Ω / □. Antimony oxide-containing tin oxide fine powder (Mitsubishi Materials Corporation, product number: T-
1) To 100 parts by weight, a conductive paint comprising 100 parts by weight of a copolymer of 2-hydroxypropyl acrylate and vinyl chloride and 350 parts by weight of cyclohexanone is applied on a metal thin film and dried to have an antistatic layer. A transparent conductive sheet was obtained. The thickness of the antistatic layer was 2 μm.

Example 2 A metal thin film was formed by sputtering silver on the surface of a polymethyl methacrylate plate having a thickness of 3 mm. The surface resistance of this metal thin film was 6Ω / □. 100 parts by weight of dipentaerythritol hexaacrylate per 100 parts by weight of fine powder of tin oxide containing antimony oxide (manufactured by Mitsubishi Materials Corporation, product number: T-1),
A photocurable antistatic paint composed of 4 parts by weight of thioxanthone, 4 parts by weight of dimethylaminoacetophenone, and 350 parts by weight of cyclohexanone is applied on a metal thin film, dried, cured by irradiating ultraviolet rays, and cured to have a transparent antistatic layer. A conductive sheet was obtained. The thickness of the antistatic layer was 1.5 μm.

(Comparative Example 1) A 150-mesh plain woven fabric made of 30-denier polyester fiber was electrolessly plated with nickel to a thickness of 0.38 μm and electrolessly plated, and a 1.5 mm-thick polyvinyl chloride plate was used. 160 ° C sandwiched between two pieces
Then, the polyvinyl chloride plate was melted by hot pressing at a pressure of 30 kg / cm ² to produce an electromagnetic wave shielding plate integrated with a conductive woven fabric embedded therein. In order to make the surface of the polyvinyl chloride plate conductive, the same conductive paint as that used in Example 1 is applied to the surface of the polyvinyl chloride plate on one side and dried to have an antistatic layer having an antistatic layer. A transparent conductive sheet was obtained. The thickness of the antistatic layer is 2μ
m.

The physical properties of the transparent conductive sheets obtained in Examples 1 and 2 and Comparative Example 1 were measured according to the following methods. Measurement method (1) Transparency The total light transmittance was measured according to ASTM-D1003. (2) Perspective image sharpness Measured according to the image sharpness measuring method of JIS K7105. The measured value was a value when the width of the optical comb was 0.125 mm. (3) Antistatic property The surface resistivity was measured according to ASTM-D257. (4) Electromagnetic Wave Shielding Property The shielding effect of the electric field at 100 MHz was measured by the Advantest method. Table 1 shows the above results.

[0017]

[Table 1]

As is apparent from Table 1, those of Examples 1 and 2 have a smaller surface resistance value than those of Comparative Example 1, and are excellent in transparency and image clarity.

[0019]

As described above, the transparent conductive sheet of the present invention has excellent transparency, antistatic property and electromagnetic wave shielding property, and is composed of conductive fine particles and a resin binder. The barrier layer protects the metal thin film without degrading performance. Therefore, since the other side can be clearly seen through the transparent synthetic resin sheet and the transparent conductive sheet, it can be suitably used for a display of a computer, a cover of a semiconductor manufacturing apparatus, and the like.

Claims (1)

[Claims] 1. A transparent conductive sheet comprising a transparent synthetic resin sheet, a transparent metal thin film formed on a surface of the transparent synthetic resin sheet, and a transparent antistatic layer laminated on the surface of the metal thin film.