JPH11330778A - Laminate for electromagnetic wave shield and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve flexibility, flexibility resistance, conductivity, and electromagnetic wave shielding property by laminating a metal thin-film layer with a sheet form and a textile fabric layer as the required constituents. SOLUTION: A metal thin-film layer 1 can shield electromagnetic waves for a metal cloth using a conductive metal string even if the fabric (mesh) is of a shape with an air gap in cross section. A metal thin film or a synthetic resin film layer 2 for reinforcing the metal fabric may be laminated between layers or the outside, thus improving such physical strength as flexibility resistance and compression resistance. When a synthetic resin film that is 1-20 μm thickness is to be used as the base of a metal thin film, a synthetic resin film such as ethylene-acetic vinyl copolymer, ABS resin, and polycetal is used. A fabric and a nonwoven fabric that are 30-300 μm thickness can be used as a textile fabric layer 4, and each laminate is used by applying an urethane-based adhesive. Although there is no restriction on the order of laminations, the metal layer is to be the outermost layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a laminate for shielding electromagnetic waves, and more particularly to a laminate for shielding electromagnetic waves for preventing electromagnetic interference from electronic and electrical equipment and electric wiring. is there.

[0002]

2. Description of the Related Art In recent years, electronic devices such as personal computers and mobile phones have been rapidly developed, and have been reduced in size and weight, highly integrated, and operated at high speed. However, communication disturbance has become a major problem. In addition, it has been pointed out that these electromagnetic waves may have an adverse effect on the human body, and there is a movement to regulate such harmful electromagnetic waves (hereinafter referred to as EMI). The reality is that the importance of technology is growing rapidly.

It is known that various metals and conductive paints can be used as an electromagnetic wave shielding material for EMI countermeasures. However, there is no material that satisfies all uses, and there is no target material for electromagnetic waves. Depending on the type and environment of use, it is necessary to devise ways to combine the most suitable materials and usage forms.

For example, when an electromagnetic wave shielding material is used for a member of a housing, a gasket or the like of an electric or electronic device such as a notebook personal computer or a mobile phone, the electromagnetic wave shielding material is usually wound around a cushioning base material such as polyurethane foam. Used in. Therefore, in addition to electric conductivity, flexibility and elasticity have been required as necessary characteristics of the electromagnetic wave shielding material.

Conventionally, as such an electromagnetic wave shielding material, a metal-plated woven fabric obtained by performing a metal plating process on a fiber cloth has been widely used. However, since the metal-plated fabric is manufactured by dipping the fiber cloth in a metal plating solution, there is a problem that the texture is hard and the flexibility is lacking. Also, because of this, the continuous part of the metal breaks during use,
There has been a problem that the conductivity tends to decrease. Further, the metal plating method is regulated in the production method because a large amount of a cyanide solution or the like which has an adverse effect on the environment is discharged.

On the other hand, an electromagnetic wave shielding material in which a metal thin film is laminated on a synthetic resin film is already widely used, but has a problem that it is easily broken. For this reason, it has been unsuitable to apply electromagnetic wave shielding to members such as a notebook personal computer housing and a gasket which are also used as a cushion material by the conventional technique.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and provides an electromagnetic shielding laminate having excellent flexibility and bending resistance, high conductivity and electromagnetic shielding properties. That is the task.

[0008]

The present invention, in order to solve the above-mentioned problems, is roughly divided into the following two main constitutions.

That is, a first configuration of the laminate for electromagnetic wave shielding according to the present invention is obtained by laminating a sheet-like (1) metal thin film layer and (2) a fiber fabric layer as essential components.

In this case, compared to the conventional metal-plated fabric, the metal layer is continuous (metal thin film), so that the conductivity is excellent, and the flexibility and bending resistance are improved by reinforcing with a fiber cloth. Can be compatible.

A second configuration has a sheet form (1).
It is obtained by laminating a metal fabric layer and (2) a fiber fabric layer as essential components. That is, instead of the metal thin film layer, the entire metal fabric is laminated.

[0012] In this case, the laminate becomes flexible, so that a laminate having further excellent flexibility and bending resistance is obtained.

[0013] The laminate for electromagnetic wave shielding of the present invention comprises at least a metal thin film layer having a sheet form or a metal fabric layer having a sheet form, and a fiber cloth layer.
It can be manufactured by laminating by an adhesion method or a lamination method.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 and 2 are longitudinal sectional views showing a first embodiment (the above-described first configuration) of an electromagnetic wave shielding laminate according to the present invention, wherein 1 is a metal thin film layer or a metal fabric layer. Reference numeral 2 denotes a synthetic resin film layer, reference numeral 3 denotes an adhesive layer, and reference numeral 4 denotes a fiber fabric layer, which are integrally laminated by, for example, a normal laminating method.

By the way, the metal thin film layer 1 does not necessarily have to be a continuous thin film in order to achieve the above-mentioned object of the present invention, and the present inventors have conducted intensive studies on the electromagnetic wave shielding mechanism. Even in the case of a woven fabric (mesh) having a void portion in the cross section, an electromagnetic wave can be shielded by using a metal woven fabric using a conductive metal thread. This second
According to the embodiment, it is possible to further improve the problems such as a decrease in the conductivity due to the peeling of the plating of the plated cloth and a tendency of the thin film of the metal thin film laminate to be easily broken, which have been problems in the past.

Further, in order to reinforce the metal thin film and the metal fabric, a synthetic resin film layer may be laminated between any of the above-mentioned layers or on the outside. In this way, bending resistance,
This has the effect of improving physical strength such as compression resistance.

The electromagnetic wave shielding laminate of the present invention has an electromagnetic wave shielding property of 30 to 75 dB, and if the electromagnetic wave shielding property is less than 30 dB, the shielding property is insufficient. On the other hand, the upper limit is 75 dB. In the case of a single metal layer constituting the laminate, the frequency of the electromagnetic wave is 100 MHz to 1000 MHz.
It would be the limit of shielding in the band.

The thickness of the metal thin film layer is 0.01 to 100 μm
It is desirable that If the thickness is less than 0.001 μm, the electromagnetic wave shielding property decreases, and if it exceeds 100 μm, the bending resistance decreases. When a synthetic resin film is used, the thickness is desirably 1 to 200 μm. If the thickness is less than 1 μm, it is difficult to form a film, and if it exceeds 200 μm, the texture becomes hard. The thickness of the metal fabric forming the metal layer is determined by the weaving density and the wire diameter of the weaving yarn.
300 μm is preferable. If it is less than 10 μm, it is necessary to reduce the wire diameter of the metal thread, which is the weaving thread of the metal fabric, so that the tear strength of the metal fabric decreases, and if it exceeds 300 μm, the wire diameter increases. Since the texture becomes hard, the flexibility of the laminate is lost, which is not preferable.

As the weaving density of the metal fabric capable of shielding electromagnetic waves, it is preferable that the weaving density is high because the yarn and the gap between the yarns become small. When the weaving density is 50 to 400 yarns / inch, preferably 200 yarns / inch or more, and more preferably 300 yarns / inch or more, an excellent effect of shielding electromagnetic waves is exhibited. If it is less than 50 inches, an electromagnetic wave shielding effect can hardly be obtained. On the other hand, the upper limit is up to 400 yarns / inch because there is a limit to the fineness of the metal yarn constituting the metal fabric and a limit to commercialization such as difficulty in weaving. In addition, the wire diameter of the metal yarn of the woven yarn used for the metal fabric needs to be smaller as the density increases due to the relationship with the weaving density, but the metal fabric of the present invention preferably has a wire diameter of 10 to 200 μm, preferably. It is important to use a thickness of 15 to 150 μm so as not to harden the feeling when the laminate is formed. Further, the metal fabric is less flexible than the metal thin film, but is excellent in physical durability such as bending resistance.

Although there is no restriction on the order of lamination of the laminate for electromagnetic wave shielding of the present invention, in particular, since members such as a housing and a gasket require conductivity on the surface, at least one member is preferable. It is desirable that the metal layers be laminated so that they are the outermost. However, when used for building materials such as wall materials and curtain materials that require an electromagnetic wave shielding function, the metal layer does not need to be the outermost layer, and a plurality of metal layers and fiber fabric layers are laminated and used without any particular restrictions. can do.

When a synthetic resin film is used as the base of the metal thin film, polyethylene terephthalate, polyphenylene oxide, polypropylene, polyphenylene sulfide, polyimide, polybutylene terephthalate, polyamide, polyethylene, polycarbonate,
Polystyrene, polyvinyl chloride, polyvinylidene chloride,
Synthetic resin films such as polyvinyl acetate, polymethyl methacrylate, ethylene-vinyl acetate copolymer, ABS resin and polyacetal can be used.

When used as a housing or a gasket material, the surface resistance of the metal thin film layer and the metal fabric is desirably 5 Ω / □ or less. Further, when it is used for a base portion or the like which is easily charged, it is preferably 1 Ω / □ or less, more preferably 0.1 Ω / □ or less.

The tear strength of the laminate is desirably 1 N or more. By reinforcing with a fiber cloth, both flexibility and bending resistance (strength) can be achieved.

The type of metal to be laminated is not particularly limited as long as it has conductivity, but silver, copper, nickel, gold, aluminum, stainless steel, iron alone or a combination thereof can be preferably used. In particular, silver, copper, gold, and aluminum are preferably used as those having a large electromagnetic wave reflection loss. Iron having a large electromagnetic wave absorption loss is preferably used. Aluminum is preferably used as a metal that achieves both such metal performance, economy and light weight.

As the fiber cloth, a woven fabric, a knitted fabric, a non-woven fabric or the like can be preferably used, but when a tear strength is required, a woven fabric or a knitted fabric is preferable, and a tricot knitted fiber fabric is particularly preferable. .

The method of laminating each of the above-mentioned laminates is not particularly limited, and lamination is performed by an adhesion method or a lamination method.
Although it can be integrated with an apparatus such as a calender, a press machine, or a hot press roll, a laminating method is preferable in terms of productivity and cost.

The laminate for shielding electromagnetic waves according to the present invention can be used as a housing material for notebook personal computers that require cushioning, a gasket, a covering material for electric wires, and a building material for electromagnetic shielding (curtains, flooring materials, wallpaper), etc., depending on the lamination method. Can be widely used.

[0029]

Embodiments will be described below with reference to embodiments. The evaluation was carried out by the following method. [Evaluation of Shielding Property] The shielding property was measured in accordance with the Kansai Electronics Promotion Center (KEC) using an EMI shielding measuring instrument and a spectrum analyzer manufactured by Anritsu Corporation. , 1 to 1000 MHz.

[Evaluation of Surface Resistance] The surface resistance (Ω / □) was measured by a four probe method according to JIS K7194.

[Bending resistance test] The bending strength was measured by the following method according to the Japanese-Chinese method, in which changes in bending strength, cracks, tears, and the like received during practical use were observed.

As samples, three pieces each of 5 cm in length and 4 cm in width were collected. The test piece was folded in two in the long side direction with the surface of the test piece facing outward, and the short side was attached to the grip of a bending test machine with a grip interval of 3 cm. Moving distance 2cm, bending speed 1
Bend 300 times at 00 times / minute. The surface after bending was observed, classified according to the following criteria, and expressed as an average of three sheets.

Grade tertiary: no cracks or base fabric tears secondary: slight cracks or base fabric tears first grade: considerable cracks or base fabric tears [Evaluation of tear strength] The tear strength was JIS. According to L 1096, the tearing speed is 15 cm per minute by the traveloid method.
Was measured.

Example 1 A 9 μm thick polyethylene terephthalate film was prepared as a synthetic resin film layer, and aluminum was deposited on one side of the film to obtain a 0.01 μm thick metal thin film layer. A urethane-based adhesive was applied to the side of the film where the polyethylene terephthalate film was exposed by a gravure coating method, and a polyester multifilament tricot knitted fabric having a total fineness of 30 deniers and 12 single yarns (vertical density 3
3.5 lines / inch x 49 horizontal densities 49 lines / inch)
The synthetic resin film layer provided with the metal thin film layer was laminated together with the surface having no metal thin film layer to obtain a laminate having the cross-sectional shape shown in FIG.

Example 2 In place of the aluminum deposited layer having a thickness of 0.01 μm of Example 1,
The same operation as in Example 1 was performed except that an aluminum vapor-deposited layer having a thickness of 0.05 μm was used to obtain a laminate having a cross-sectional shape shown in FIG.

Example 3 In place of the aluminum deposited layer having a thickness of 0.01 μm of Example 1,
The same operation as in Example 1 was carried out except that an aluminum vapor-deposited layer having a thickness of 1 μm was used to obtain a laminate having a cross-sectional shape shown in FIG.

Example 4 A urethane-based adhesive was applied to one surface of an aluminum foil having a thickness of 10 μm by a gravure coating method, and a polyester multifilament tricot knitted fabric having a total fineness of 30 deniers and 12 single yarns (vertical density: 33.5) / Inch × lateral density 49 lines / inch) to obtain a laminate having a cross-sectional shape shown in FIG.

Example 5 Example 4 was repeated except that a 20 μm thick aluminum foil was used instead of the 10 μm thick aluminum foil of the fourth example.
In the same manner as in the above, a laminate having a cross-sectional shape shown in FIG. 2 was obtained.

Example 6 Instead of the knitted fabric of Example 3, a polyester multifilament flat knitted fabric having a total fineness of 30 denier and 12 single yarns (vertical density: 120 / inch × lateral density: 70 / inch)
Was performed in the same manner as in Example 3 except that a laminate having a cross-sectional shape shown in FIG. 1 was obtained.

Example 7 The same operation as in Example 3 was carried out except that a polyester nonwoven fabric was used instead of the knitted fabric of Example 3, to obtain a laminate having a sectional shape shown in FIG.

Example 8 A laminated body having the cross-sectional shape shown in FIG. 1 was obtained in the same manner as in Example 3, except that a copper vapor deposition layer was used instead of the aluminum vapor deposition layer of Example 3.

Example 9 The same operation as in Example 4 was carried out except that a foil obtained by vapor deposition of nickel on a copper foil was laminated so that nickel became the outermost layer instead of the aluminum foil of Example 4, and the cross section shown in FIG. A laminate having a shape was obtained.

Example 10 A urethane-based adhesive was applied by gravure coating to one side of a metal fabric having a thickness of 60 μm, a wire diameter of 30 μm, a weaving density of 250 pieces / inch, and a total fineness of 30 denier. It was laminated on a polyester multifilament tricot knitted fabric having 12 threads (vertical density: 33.5 / inch × lateral density: 47 / inch) to obtain a laminate having a cross-sectional shape shown in FIG.

Table 1 summarizes the configurations and evaluation results of Examples 1 to 10.

Comparative Example 1 In place of the aluminum deposited layer having a thickness of 0.01 μm of Example 1,
A laminate was obtained in the same manner as in Example 1, except that an aluminum vapor-deposited layer having a thickness of 0.001 μm was used.

Comparative Example 2 A laminate was obtained in the same manner as in Example 4, except that a 150 μm thick aluminum foil was used instead of the 10 μm thick aluminum foil of Example 4.

Comparative Example 3 A 9 μm thick polyethylene terephthalate film was prepared as a synthetic resin film layer, and aluminum was deposited on one side of the film to obtain a 1 μm thick metal thin film layer.

Comparative Example 4 An aluminum foil having a thickness of 20 μm was used as Comparative Example 4.

Comparative Example 5 A polyester multifilament plain fabric having a total fineness of 30 deniers and 12 single yarns (vertical density: 120 / inch ×
50 g / m ² of metal adhesion amount at a horizontal density of 70 pieces / inch)
Copper / nickel plating was performed.

Comparative Example 6 A urethane-based adhesive was applied by gravure coating to one surface of a metal fabric having a thickness of 400 μm, a wire diameter of 230 μm, a weaving density of 30 pieces / inch, and a total fineness of 30 denier. It was laminated on a polyester multifilament tricot knitted fabric having 12 threads (vertical density: 33.5 / inch × lateral density: 49 / inch) to obtain a laminate having a sectional shape shown in FIG.

The structures of Comparative Examples 1 to 5 are the same as in
Are shown together.

With respect to Examples 1 to 10 and Comparative Examples 1 to 6, the surface resistance, the shielding property, the tear strength, and the bending strength were evaluated in accordance with the above-mentioned methods.

[0053]

[Table 1]

[0054]

[Table 2]

From Table 2, the laminate obtained in each example was
It can be seen that the laminate for electromagnetic wave shielding is superior in conductivity, shielding properties, strength, and bending resistance as compared with the comparative example.

[0056]

The laminate for shielding electromagnetic waves according to the present invention is excellent in conductivity, shielding properties, strength, and bending resistance. Building materials (curtains,
Floor, wallpaper etc) can be widely used.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of an electromagnetic wave shielding laminate according to the present invention.

FIG. 2 is a cross-sectional view of the laminate of the present invention in which a synthetic resin film layer is laminated inside the laminate of FIG.

[Explanation of symbols]

 1: metal thin film layer 2: synthetic resin film layer 3: adhesive layer 4: fiber cloth layer

Continued on the front page (72) Inventor Masanobu Takeda 1-1-1 Oe, Otsu City, Shiga Prefecture Toray Industries, Inc. Seta Plant

Claims (17)

[Claims] 1. A laminate for electromagnetic wave shielding, comprising two or more laminates, wherein (1) a metal thin film layer having a sheet form and (2) a fiber fabric layer are contained as essential components. 2. A laminate for electromagnetic wave shielding, comprising two or more laminates, wherein (1) a metal fabric layer having a sheet form and (2) a fiber fabric layer are contained as essential components. 3. The electromagnetic wave shielding laminate according to claim 1, further comprising (3) a synthetic resin film layer as an essential component. 4. The electromagnetic wave shielding property of the laminate is 30 to 7
4. The method according to claim 1, wherein the range is 5 dB.
The laminate for electromagnetic wave shielding according to any one of the above. 5. The synthetic resin film layer has a thickness of 1 to 20.
The laminate for electromagnetic wave shielding according to claim 3, wherein the thickness is 0 µm. 6. The metal thin film has a thickness of 0.01 to 100 μm.
The laminate for electromagnetic wave shielding according to any one of claims 1 to 5, wherein m is an integer. 7. The laminate for electromagnetic wave shielding according to claim 2, wherein the thickness of the metal fabric is in a range of 30 to 300 μm. 8. The weaving density of the metal fabric is 50 to 50 for both weft and weft.
The electromagnetic wave shielding laminate according to claim 7, wherein the number is in the range of 400 lines / inch. 9. The electromagnetic wave shielding laminate according to claim 7, wherein at least one of the metal yarns constituting the woven yarn of the metal fabric has a warp wire diameter in the range of 10 to 200 μm. 10. The laminate for electromagnetic wave shielding according to claim 1, wherein the laminate has a surface resistance of 5Ω / □ or less. 11. The laminate for electromagnetic wave shielding according to claim 1, wherein the laminate has a tear strength of 1 N or more. 12. The electromagnetic wave shielding laminate according to claim 1, wherein the metal thin film or the metal fabric is one selected from aluminum, silver, copper, nickel, and stainless steel. 13. The laminate for electromagnetic wave shielding according to claim 1, wherein the fiber cloth is a woven or knitted fabric. 14. An electronic device housing comprising the electromagnetic wave shielding laminate according to claim 1. 15. A gasket for electronic equipment, comprising the electromagnetic wave shielding laminate according to claim 1. Description: 16. An electric wire covering material comprising the electromagnetic wave shielding laminate according to any one of claims 1 to 13. 17. A method of manufacturing a laminate for electromagnetic wave shielding, comprising laminating at least a metal thin film layer having a sheet form or a metal fabric layer having a sheet form and a fiber fabric layer by an adhesion method or a lamination method. Method.