JP2000233463A - Electrically conductive sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a sheet, which is equipped with excellent electromagnetic wave shielding properties without lowering its electrical conductivity and, at the same time, no large-scaled device is necessary for manufacturing and can be manufactured by a simple process by a method wherein a photopolymerizable acrylic resin composition infiltrated in an electrically conductive fiber sheet is set by being irradiated with ultraviolet rays. SOLUTION: A photopolymerizable acrylic resin composition is infiltrated in an electrically conductive fiber sheet so as to be set by being irradiated with ultraviolet rays. In this case, as the electrically conductive fiber sheet, synthesized organic fibers such as nylons or the like, the surface of each of which is covered with a highly electrically conductive metal such as silver, copper, or the like, and which are formed into a net- or honeycomb-like shape, is employed. Further, as the photopolymerizable acrylic resin composition, a hardening acrylic ester resin or the like is employed. As a result, no lowering of the electrical conductivity due to the oxidation of the metal occurs and the sheet is equipped with excellent electromagnetic wave shielding properties or the like. At the same time, no large-scaled device is necessary for manufacturing the sheet. The sheet can be manufactured by a simple process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive sheet having excellent electromagnetic wave shielding properties and transparency without lowering the conductivity, and a method for producing the same.

[0002]

2. Description of the Related Art Electromagnetic wave shielding technology for protecting electronic components used in electronic devices from static electricity and electromagnetic waves is based on circuit design techniques such as shielding, filtering, and wiring methods, and equipment. It is known to use various electromagnetic wave shielding materials for the housing.

Among them, the electromagnetic wave shielding technology for the housing of electronic equipment includes a method of applying a conductive paint to a housing material, a method of spraying zinc on a synthetic resin base, an aluminum plating, and a synthetic resin mixed with a conductive filler. There is known a method of forming a resin. In the case of a synthetic resin film, a method of bonding a metal foil such as an iron foil, an aluminum foil, and a copper foil, and a method of forming a thin film of ITO or nickel on one side of a polyester film or the like by a sputter deposition method are also known. is there.

As a method for producing a transparent conductive resin film, there is known a method in which a transparent resin extruded from a T-die is penetrated into a web of conductive fibers (Japanese Patent Laid-Open No. 64-64).
No. 9716). In the conductive resin film obtained by this method, the metal of the conductive fiber or the metal of the metal-plated fiber is oxidized by the heat of the extruded resin, whereby the desired conductivity and electromagnetic wave shielding properties are sufficiently exhibited. There is a disadvantage that it disappears.

[0005] Japanese Patent Publication No. 2-48159 discloses a fast-curing ink prepared by uniformly mixing a metal powder and an ultraviolet-curable epoxy acrylate resin in a grid or stripe pattern on a light-transmitting plate or film. An electromagnetic wave shielding material is described in which the resin is cured by irradiating the resin. Since this product is based on UV curing, it does not require high-temperature heat during molding, is excellent in electromagnetic wave shielding, and is lightweight.However, UV curable ink is printed on films etc. in a predetermined pattern during manufacturing. It requires a process of doing.

Japanese Patent Application Laid-Open No. Hei 7-297591 discloses that
An electromagnetic wave shielding film having a transparent conductive thin film in which a metal oxide is laminated on one surface of a transparent film by a vacuum evaporation method, a sputtering method, an ion plating method or the like is disclosed. Although this is used in a liquid crystal display device and has various effects, it requires an apparatus and a process for laminating a metal on a transparent film in manufacturing.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, requires excellent electromagnetic wave shielding and transparency without deteriorating conductivity, and requires a large-scale apparatus for manufacturing. It is an object of the present invention to provide a conductive sheet and a method for manufacturing the same, which can be manufactured by simple steps.

According to the present invention, there is provided a conductive sheet according to the present invention, in which a conductive fiber sheet is impregnated with a photopolymerizable acrylic resin composition, and the photopolymerizable acrylic resin composition is irradiated with ultraviolet rays. Is cured.

[0008] The conductive sheet according to the second aspect is the first aspect.
The conductive sheet according to any one of the preceding claims, wherein the conductive fiber sheet is a net-like structure of organic fibers coated with a conductive metal.

According to a third aspect of the present invention, in the method for manufacturing a conductive sheet, the conductive fiber sheet is impregnated with a photopolymerizable acrylic liquid resin composition and defoamed, and then the resin impregnated sheet is irradiated with ultraviolet rays. The photopolymerizable acrylic liquid resin composition is thereby cured.

In the present invention, the conductive fiber sheet includes nylon,
Synthetic organic fibers such as polyester, the surface of which is coated with a highly conductive metal such as silver or copper, is formed into a sheet such as a net, a honeycomb, a woven, or a nonwoven, Particularly, a net-shaped or honeycomb-shaped one is preferable. Electromagnetic waves and currents that have reached the conductive fiber sheet do not concentrate locally, but flow on the fiber surface of the net-shaped or honeycomb-shaped fiber sheet and diffuse radially without causing electrical interference. Therefore, the electromagnetic waves and the current disappear immediately.

The photopolymerizable acrylic resin composition includes:
Curable acrylate resins are preferred, and specifically, arylated acrylate derivatives such as bisphenol-A, urethane acrylates, polyester acrylates, epoxy acrylates, and the like;
It comprises a base resin composed of a mixture of at least two or more species, an oligomer containing an unsaturated group, and a photopolymerization initiator that absorbs light energy to generate active species such as radicals.

Examples of the crosslinking agent include tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, methoxytriethylene glycol, A vinyl group at the terminal such as isobonyl acrylate, neopentyl glycol acrylate, pentaerythritol tri (meth) acrylate,
And a monomer of an acrylate ester.
The compounding amount of the crosslinking agent is preferably 20 to 80% by weight in the curable acrylate resin composition.

As a method of defoaming after impregnating a fiber sheet with the above liquid resin composition, for example, a method of expelling air by compressing the resin impregnated sheet in the thickness direction, or sealing the impregnation tank, A method of defoaming under reduced pressure can be adopted.

[0014]

Embodiments of the present invention will be described below. (Examples 1 to 6) The following were used as raw materials. Acrylic resin (arylated acrylate derivative) Brominated bisphenol A diacrylate (manac, trade name "EBR-100") Urethane acrylate (Nippon Synthetic Chemical Company, trade name "Shikko UV3000B") bisphenol A diacrylate Bisphenol A diacrylate (trade name "Epoxy Ester EA1020" manufactured by Shin-Nakamura Chemical Co., Ltd.) Benzyl methacrylate (trade name "Light Ester BZMA" manufactured by Mitsubishi Rayon Co., Ltd.) Dimethacrylate (manufactured by Kyoeisha,
Product name “14EG-A”) Photopolymerization initiator Phenyl 2-hydroxy-2-propyl ketone (Ciba Geigy, product name “Drocur 1173”) Release agent Special alkyl group alcohol (Moldwiz, product name “EQ”) -6 ") Conductive fiber woven fabric A nylon 6 fiber surface coated with a silver compound is formed into a mesh with a fiber gap of 1.5 mm.

A conductive fiber sheet is impregnated with an acrylic resin having the composition shown in Table 1, sandwiched between two glass plates, and defoamed by pressing the four corners with a vice for an experiment, and ultraviolet rays are applied thereto. Irradiation was performed at an intensity of 80 W / cm for 60 seconds to cure the resin.

(Comparative Example 1) The conductive fiber sheet used in the example was covered with polyethylene pellets,
After heating and pressing at 150 ° C. and 150 kg / cm ² for one and a half minutes, the resultant was cooled to obtain a fiber sheet.

Performance Evaluation (1) Total light transmittance: (2) Electric field attenuation: The electric field attenuation at 10 MHZ and 100 MHZ was measured by the Advantest method. (3) Haze: The above results are shown in Table 1.

[0018]

[Table 1] [Note: Amounts are parts by weight. ]

From Table 1, it is clear that Examples 1 to 6 have better electromagnetic wave shielding properties and transparency than those of Comparative Examples.

[0020]

The conductive sheet of the present invention has excellent electromagnetic shielding properties without a decrease in conductivity due to metal oxidation. Further, according to the method for producing a conductive sheet of the present invention, a large-scale apparatus is not required for the production, and the conductive sheet can be produced by a simple process.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 13/00 503 H01B 13/00 503A H05K 9/00 H05K 9/00 V // B32B 7/02 104 B32B 7/02 104 F term (reference) 4F100 AB01A AB24 AB25 AK01A AK25A AK41 AK48 BA01 CA02 DC01 DG01A DG11A DG12 DG13 DG15 EH66A EJ08A EJ082 EJ54A DD EJ542 EJ82A EJ822 EJ952 JB01 GG01 JB01 BB01 BB01 BB 5G307 FA02 FB02 FC09 FC10

Claims (3)

[Claims] 1. A conductive sheet comprising a conductive fiber sheet impregnated with a photopolymerizable acrylic resin composition, and the photopolymerizable acrylic resin composition cured by irradiation with ultraviolet rays. 2. The conductive sheet according to claim 1, wherein the conductive fiber sheet is a net-like structure of organic fibers coated with a conductive metal. 3. The conductive fiber sheet is impregnated with the photopolymerizable acrylic liquid resin composition and defoamed, and then the resin impregnated sheet is irradiated with ultraviolet light to cure the photopolymerizable acrylic liquid resin composition. A method for producing a conductive sheet, comprising: