JPH0418542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a conductive sheet or film, and particularly to a conductive sheet or film having excellent colorability and durability.

(Prior technology) Semiconductor wafer storage containers, electronic/electrical components, wall materials and flooring materials for semiconductor manufacturing plants, bio-clean rooms, etc. are required to have an antistatic function in order to prevent the adhesion of dust in the air. There are many cases where

Japanese Utility Model Application Publication No. 58-48435 discloses a conductive decorative plate for antistatic purposes. This conductive decorative board consists of processed paper as a material layer and a resin layer as a surface material, and carbon fiber is mixed into the processed paper. Since the black color of the carbon fibers can be seen through the resin layer, the resulting conductive decorative board has a black color as a whole. However, since the conductive decorative board to be used as wall and flooring materials is black in color, its application areas are extremely limited.
Not practical. Therefore, in order to hide this black color, the resin layer is made thicker or a printed layer containing a pigment is formed on the base material layer. However, this method has a problem in that the conductivity of the decorative board decreases.

(Problems to be Solved by the Invention) The present invention is intended to solve the above-mentioned conventional drawbacks, and its purpose is to provide a sheet or film that has excellent conductivity and colorability.

(Means and effects for solving the problems) The conductive sheet or film of the present invention includes conductive powder and/or conductive whiskers and pigments on the surface of a woven or nonwoven fabric for a base material containing conductive fibers. The above-mentioned object is achieved by providing a printed layer containing the following, and providing a thermosetting or thermoplastic resin coating layer on the surface of the printed layer.

The conductive woven fabric or nonwoven fabric for a base material (hereinafter referred to as base material) of the present invention is composed of non-conductive fibers and conductive fibers. Non-conductive fibers used in this woven or non-woven fabric include glass fiber, rock wool, cellulose fiber, and synthetic polymer fiber. Examples of the conductive fibers include carbon fibers; metal fibers such as stainless steel and aluminum; glass fibers coated with metals such as aluminum, zinc, and nickel. The length of these conductive fibers is preferably 3 mm or more. If it is too small, sufficient conductivity cannot be obtained. The thickness of the fibers is preferably fine in order to obtain sufficient conductivity with a small amount. A suitable thickness is 50 μm or less. The conductive fibers are mixed in an amount of 3 to 4% by weight or more based on the entire base material. If it is less than this, a sufficient volume resistivity value (10 ³ to ^{10 8} Ω·cm) cannot be obtained. If the amount of conductive fibers is excessive, the shape of the woven or nonwoven fabric cannot be finished. The conductive woven fabric or nonwoven fabric can be obtained by mixing conductive fibers with non-conductive fibers by means such as weaving, knitting, papermaking, etc.

A printing layer is formed on the surface of the base material thus obtained. The printing inks used to form the printing layer include pigments, resins, conductive powders and/or
Or it contains conductive whiskers and a solvent. As the pigment, any known pigment such as titanium oxide or zinc white can be used as appropriate. As the resin, urethane resin, vinyl chloride resin, etc. are preferably used. The conductive powder is preferably a conductive powder obtained by adding a doping agent that is a trivalent or pentavalent metal to a metal oxide. For example, tin oxide doped with antimony,
These include zinc oxide doped with aluminum. The conductive whisker includes, for example, a conductive fibrous single crystal made of potassium titanate or alumina. These conductive powders and/or conductive whiskers are contained in the printing ink (solid content) in an amount of 1 to 50% by weight, preferably 1 to 25% by weight.
It is contained in a proportion of If the amount is too small, good conductivity cannot be obtained. Even if an excessive amount is used, the conductivity will not be particularly improved and the cost will only increase. As the solvent, common organic solvents such as toluene and xylene are used. The pigment, resin, and conductive powder and/or conductive whisker are mixed with this solvent to form a printing ink having an appropriate viscosity.

The printing layer formed by applying the printing ink effectively hides the color of the substrate due to the pigment contained therein. At the same time, it exhibits good electrical conductivity due to the electrically conductive powder and/or electrically conductive whiskers contained therein. These conductive powders and conductive whiskers have a white appearance and become transparent when contained in printing ink, so they do not affect the color of pigments contained therein at the same time. Therefore, a printed layer of a desired color derived from the pigment can be obtained.

In order to protect the surface of the printed layer thus formed, a film layer is further formed on the surface of the printed layer. The film layer is formed by applying a thermosetting resin or thermoplastic resin to the printing surface, and then, if necessary, performing post-treatments such as thermosetting and compression. Thermosetting resins forming the film layer include polyester, diallyl phthalate, polyurethane, melamine, and phenolic resins. Thermoplastic resins include PVC, acrylic, ethylene-vinyl acetate copolymer, butyral resin, natural rubber, synthetic rubber, and the like. These are dissolved in a solvent or heated when used.

The film layer contains conductive powder and/or conductive whiskers, if necessary, in order to increase the conductivity of the final sheet or film. As the conductive powder and the conductive whisker, those contained in the printing layer and described above are used. These conductive powders and/or conductive whiskers are contained in an amount of 50% by weight or less, preferably 1 to 25% by weight of the total resin used. If it exceeds 50% by weight, the surface strength will decrease. When a large amount of conductive powder or conductive whiskers is contained in the printed layer, sufficient conductivity can be obtained even if the coating layer does not contain conductive powder or conductive whiskers. The amount of conductive powder and conductive whiskers in the coating layer is appropriately determined depending on the conductivity of the printed layer and the thickness of the coating layer. Since conductive whiskers are in the form of fibers, when conductive whiskers are mixed in the coating layer, they are easily electrically conductive with the conductive powder and conductive whiskers in the printed layer, and therefore, the conductive powder The conductivity is improved compared to when both are present.
Therefore, the film layer can exhibit sufficient conductivity even if only a small amount of conductive whiskers are contained therein.

The sheet or film of the present invention exhibits good electrical conductivity as a whole because at least both the base material and the printed layer have electrical conductivity. Its surface resistivity value is usually 10 ² to 10 ⁸ Ω.
The color of the substrate containing metal fibers or carbon fibers (usually black to gray) is effectively hidden by the printed layer, so the coating layer provided on the printed layer can ensure the durability of the sheet or film. It is sufficient if the thickness is as small as possible. Due to the presence of the film layer, the sheet or film has excellent scratch resistance and water resistance. Therefore, it does not become a source of dust unlike conductive woven fabrics or nonwoven fabrics that do not have a film layer on their surface. This sheet or film is
It can also be used for wall and floor materials such as clean rooms and electromagnetic shielding, which require an antistatic effect.

(Example) The present invention will be explained below using examples.

Example: Printing ink having the following composition was applied to a conductive nonwoven fabric for base material (weighing 55 g/m ² ) consisting of 8% by weight of carbon fibers and 92% by weight of pulp fibers, and the printing ink was gravure-printed so that the weight after drying was approximately 13 g/m ² Coated.

Aluminum doping Zinc oxide 11% by weight Urethane resin 3% by weight Titanium oxide 58% by weight Toluene 28% by weight Polyester resin was coated on the surface of the formed white printing layer at a rate of 10 g/m ² . This polyester resin contains 10% by weight of zinc oxide doped with aluminum as a conductive powder. The paper obtained was white and had a surface resistivity of 1.8×10 ⁶ Ω.

Comparative Example 1 Same as Example except that no printing ink was applied. The surface resistivity of the obtained paper is 2.0
×15 ⁵ Ω, indicating good conductivity, but its appearance was gray.

Comparative Example 2 Same as Example except that the printing ink does not contain conductive powder. The paper obtained was white in color and had a surface resistivity of 3.0×10 ¹¹ Ω.

(Effects of the Invention) In the conductive sheet or film of the present invention, since the base layer is effectively shaded by the conductive printed layer, the conductive sheet or film can be formed into any color depending on the pigment of the printed layer. Can be colored. Since the color of the base material is hidden, there is no need to make the film layer thicker to hide the base material layer. Because of the coating layer, this sheet or film has excellent durability. By selecting an appropriate resin for this coating layer, a sheet or film with excellent chemical resistance can be obtained. Such sheets or films can be used as wall and floor materials in clean rooms, etc.
It can be used in many ways, including electromagnetic shielding.

Claims (1)

[Scope of Claims] 1. A printed layer containing conductive powder and/or conductive whiskers is provided on the surface of a woven or nonwoven fabric for a base material containing conductive fibers, and a thermosetting layer is provided on the surface of the printed layer. Or a conductive sheet or film with a thermoplastic resin film layer. 2. The conductive sheet or film according to claim 1, wherein the conductive fiber is carbon fiber, metal fiber, or glass fiber coated with a conductive material. 3. The conductive sheet or film according to claim 1, wherein the printed layer contains the conductive powder and/or conductive whiskers in a proportion of 1 to 50% by weight. 4. The conductive sheet or film according to claim 1, wherein the film layer contains conductive powder and/or conductive whiskers in a proportion of 50% by weight or less. 5. The conductive sheet or film according to claim 1 or 3, wherein the conductive powder is a conductive powder obtained by adding a doping agent to a metal oxide.