JPH0227799A - Conductive sheet - Google Patents

Abstract

PURPOSE:To obtain a conductive sheet extremely easily, without spoiling the mechanical strength of a light-transmitting supporter, by providing a porous layer of a conductive resin on the supporter. CONSTITUTION:A porous layer 2 of a conductive resin is provided on a light- transmitting supporter 1. As a supporter 1, polyester, polyethylene, polystyrene, polypropylene, polycarbonate, etc., for example, are used. As a conductive resin, a mixture of a conductive substance and resin is used. As a conductive substance, carbon black, graphite, metal powder, etc., for example, are used. By doing this, it becomes possible to obtain a conductive sheet extremely easily, without spoiling the mechanical strength of the supporter 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transparent conductive sheet used as an electromagnetic shielding material and a static electricity generation prevention material.

[Conventional technology]

BACKGROUND ART With the development of electronic devices, damage to electronic devices due to electromagnetic waves and static electricity has become a problem. The following methods are known as methods for preventing electromagnetic interference and static electricity. (1) A method of mixing a conductive filler, a conductive polymer, etc. into the surface or inside of a resin to make it a conductor, (2) A method of pasting a metal sheet on the inner surface of the housing or support surface of an electronic device, ( 6) A method of forming a metal thin film by electroplating, metal vapor deposition, etc.; (4) a method of applying metal fibers to the surface of a support or kneading them with a resin and introducing them into the interior of the support;
5) Method of applying conductive ink in a pattern, (6)
There are known methods such as (7) forming a mesh of metal wire and pasting it on the surface of the support, and (7) forming a thin film of a metal oxide, such as indium oxide, on the surface of the support.

[Problem that the invention seeks to solve]

However, in methods 1) to (3), the conductive materials used are metals, carbon, etc., which are significantly colored, and the entire surface of the support, housing, etc. is made conductive, so it is difficult to see through. I can't.

Further, although methods (4) to (c) provide transparent conductive sheets, they are extremely expensive.

The present inventors completed the present invention as a result of conducting research to develop a conductive sheet that can easily make the surface of an insulating material conductive and has light transparency.

[Means for solving intervening vertices]

The present invention is a conductive sheet characterized by having a porous layer of conductive resin on a light-transmitting support.

The structure of the conductive sheet of the present invention will be explained with reference to the drawings. The drawing is an enlarged perspective view of a conductive sheet, in which 1 indicates a light-transmitting support and 2 indicates a porous layer of conductive resin.

Preferred examples of the light-transmitting support used in the present invention include polyester, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, polyvinyl chloride, triacetate, cellulose resin, highly transparent paper or laminated paper, and glass.

As the conductive resin, a mixture of a conductive substance and a resin is used. Examples of conductive substances include carbon blank, graphite, metal powder, cuprous iodide powder, sulfide steel,
Conductive fillers such as cadmium sulfide, conductive fibers such as iron fibers, stainless steel fibers, brass fibers, and carbon fibers, conductive polymers such as polyaniline, polythiophene, and polypyrrole are used. A mixture of two or more of these conductive substances can also be used.

In addition, the resin used is a resin (brushing resin) that can form a light-transparent porous film by utilizing the difference in solubility or volatility between two types of solvents when applying and drying a resin solution. It will be done. Examples of such resins include nitrocellulose, methylcellulose, ethylcellulose, acetylcellulose, polyvinyl chloride, polystyrene, polycarbonate, polyvinyl acetate, polyvinyl butyral, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, and acrylic resins. Examples include resin. Cellulose-based at-fats such as nitrocellulose, methylcellulose, ethylcellulose, and acetylcellulose are preferred.

When manufacturing the conductive sheet of the present invention, first a coating liquid containing a conductive substance, a resin, and two types of solvents is prepared.

The ratio of conductive substance to resin in the coating solution varies depending on the conductive substance and resin, but is generally 1:20 to 20:1 by weight.
It is.

Examples of the two types of solvents include a soluble solvent and an insoluble or poorly soluble arc, or a highly volatile solvent and a low volatile solvent. Examples of the soluble solvent and the insoluble or poorly soluble solvent include the following combinations. Tetrahydrofuran or methyl ethyl ketone (
MEK) and ethanol, toluene for polystyrene, MEK or ethyl acetate and n-butanol, methylene chloride or dioxane and acetone for polycarbonate, acetone or MEK for acetylcellulose,
! : toluene, methanol or ethanol to ethylcellulose, water or toluene. The blending amount of the insoluble or poorly soluble solvent is 1 to 1 per 100 parts by weight of the soluble solvent.
00 parts by weight is preferred.

Next, when the coating liquid is applied onto a light-transmitting support and dried, a porous layer of conductive resin is formed, and the desired conductive sheet is obtained.

The diameter of the small pores in the porous layer is preferably about several μm to 200 μm. If the pore size is smaller than this, the light transmittance will decrease,
Moreover, if it is thicker than this, the conductivity decreases and a sufficient shielding effect cannot be obtained. The pore diameter of the small pores can be adjusted by changing the solid content concentration of the coating liquid, the mixing ratio of an insoluble or poorly soluble solvent to a soluble solvent, drying conditions, etc.

As the drying method, ventilation drying, heat drying, etc. are used.

〔Effect of the invention〕

The conductive sheet of the present invention can be produced very easily and economically advantageously without impairing the mechanical strength of the support.Also, since it has optical transparency, it cannot be seen through. I can do it.

Example 1 A paint consisting of the following components was prepared, and then applied onto a 5 μm transparent polyester film using a doctor bar and dried to form a porous layer with a coating thickness of about 3 μm. The conductivity of this layer was approximately 104 ohms (7), and it was possible to see through this layer.

Paint 0.05μm carbon black 2 parts ethyl cellulose 8 parts ethanol 170 parts water
50 parts Example 2 A coating material consisting of the following components was prepared, and then applied onto a 50 μm transparent polyester film using a doctor bar and dried to form a porous layer with a coating thickness of about 6 μm.

The conductivity of this layer was approximately 104 Ωa, and it was possible to see through this layer.

Paint 0.05-carbon black 2 parts polyvinyl butyral 5 parts acetone
100 parts water
60 parts Example 3 A coating material consisting of the following components was prepared, and then applied onto a 50 μm transparent polyester film using a doctor bar and dried to form a porous layer with a coating thickness of approximately 3 μm. The conductivity of this layer was approximately 102 Ωa, and it was possible to see through this layer.

Paint 0.1 μm silver powder 20 parts polyvinyl butyral 2 parts acetone
400 parts water
120 copies

[Brief explanation of the drawing]

The drawing is a perspective view of the conductive sheet of the present invention, in which symbol 1 indicates a light-transmitting support and 2 indicates a conductive resin. Applicant Tomoe River Paper Co., Ltd. Agent Patent attorney Tadashi Kobayashi Yugai (1 person)

Claims (1)

[Claims] An electrically conductive sheet comprising a porous layer of electrically conductive resin on a light-transparent support.