JP2005209687A - Electro-magnetic wave shielding cushioning material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-magnetic wave shielding cushioning material effectively shielding electro-magnetic waves leaking from an information-equipment box body such as a portable telephone and capable of protecting an electronic part comparatively weak to an impact and a manufacturing method having a simple manufacturing method and capable of easily manufacturing the cushioning material. <P>SOLUTION: The electro-magnetic wave shielding cushioning material is composed of a meshy base material (A) and a conductive adhesive resin (B) substantially burying meshes of the base material (A) and forming a coating layer on at least one surface of the base material (A). The cushioning material is further composed of conductive fibers (C) uniformly and vertically fixed on the adhesive resin (B). Such an electro-magnetic wave shielding cushioning material and its manufacturing method or the like are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a highly flexible electromagnetic shielding cushion material having a high electromagnetic shielding effect and a method for producing the same, and more particularly, to a mesh-like substrate and a coating layer on at least one surface of the mesh substrate. The present invention relates to an electromagnetic wave shielding cushion material composed of a conductive adhesive resin that forms a film, and conductive fibers that are uniformly and vertically fixed on the adhesive resin, and a method for manufacturing the same.

In recent years, with the advancement of electronic technology, a large number of electronic devices using electricity, electrons, radio waves and the like have become widespread, and accordingly, the electronic devices are rapidly becoming higher in frequency, digitized and highly integrated. Some of them emit electromagnetic waves that have harmful effects on humans and other devices, but recently they have become particularly problematic, and countermeasures to prevent them are becoming extremely important. is there.
There are various countermeasures against electromagnetic interference. However, what is regarded as a preventive countermeasure is a conductive material used as an electromagnetic shielding material having electromagnetic shielding performance. The electromagnetic shielding material is a material that prevents electromagnetic waves from the outside from entering the inside or blocks the electromagnetic waves from the inside by covering an electronic device or a building with a shielding material.

In general, the following four methods are representative and various proposals have been made when looking at techniques for imparting electromagnetic wave shielding performance or conductive performance to a polymer material (polymer) such as plastics or rubber.
(I) A technique in which a conductive material is mixed and dispersed inside a polymer such as plastics, rubber, or foam (see, for example, Patent Document 1).
(Ii) A technique of embedding a conductor such as metal or a conductive material in a polymer matrix (for example, see Patent Documents 2, 3, and 4).
(Iii) A technique for forming a conduction path on the polymer surface or inside by chemical plating or vapor deposition of metal or the like (see, for example, Patent Document 5).
(Iv) A technique of sticking or laminating a highly conductive material on a polymer surface (for example, see Patent Document 6).

However, the conventional proposed technique has various problems.
For example, in the technique of mixing and dispersing the conductive material (i) in the polymer, when carbon black is used as the conductive material, for example, high concentration filling is required and good conductivity is exhibited. At a high filling rate, the mechanical properties become inferior. On the other hand, in order to reduce the filling rate, expensive raw materials such as silver are required. Moreover, the manufacturing method by an impregnation method has the difficulty that a process is complicated.
Further, in the technique of embedding the conductive material (ii) in the polymer matrix, those in which a mesh, metal foil, expanded metal, etc. are embedded are restricted in their thickness and have anisotropy, that is, etc. In some cases, the conductive three-dimensional mesh is embedded, and the conductivity varies depending on the density of the mesh in the polymer. Furthermore, in order to obtain good conductivity, high density filling (embedding) is required, and as a result, there is a problem that the cushioning property is lost.
Further, in the technique (iii) of chemical plating or vapor deposition of metal or the like, the plating layer on the contact surface portion such as the casing is likely to fall off due to rubbing when exerting a buffer action such as shock absorption. It is difficult to exhibit stable performance.
Further, in the technique of attaching (or laminating) the highly conductive material (iv) to the polymer surface, the conductive layer does not have an elastic property when the metal fine wire mesh or the like is pasted. The cushioning property is worse. In addition, there is a problem that the adhesion of the contact portion such as the casing is deteriorated and electromagnetic waves are likely to leak.
As described above, since the proposed conventional electromagnetic shielding conductive material has various problems, it has excellent electromagnetic shielding properties that eliminate these problems, and a conductive cushion material is strongly desired. It is rare.

JP-A-7-249890 (Claims etc.) Japanese Patent Laid-Open No. 10-237184 (Claims etc.) Japanese Patent Laid-Open No. 11-68376 (Claims etc.) JP 2001-85888 A (Claims etc.) JP 2002-164684 A (Claims etc.) JP-A-6-85488 (Claims etc.)

  The object of the present invention is to solve the problems of the above-mentioned conventional conductive materials, effectively cut off electromagnetic waves leaking from information equipment housings such as mobile phones, and protect electronic components that are relatively vulnerable to impact. Another object of the present invention is to provide an electromagnetic shielding cushion material having a buffering function that can be produced, and a production method that can be easily and easily produced.

  As a result of intensive research in view of the above problems, the present inventor applied a conductive adhesive resin such as a conductive adhesive to the mesh of a mesh-like substrate such as a wire mesh, and the conductive adhesion. The conductive resin layer is electrostatically implanted with conductive fibers in the vertical direction to produce an electromagnetic shielding cushion material.The electromagnetic shielding cushion material has a high electromagnetic shielding effect, and further, since it is implanted, It was found that it is flexible and excellent in buffering action. The present invention has been completed based on these findings.

That is, according to the first invention of the present invention, the mesh substrate (A) and the mesh of the mesh substrate (A) are substantially filled, and at least one surface of the mesh substrate (A). Provided is an electromagnetic shielding cushion material comprising a conductive adhesive resin (B) for forming a coating layer thereon, and conductive fibers (C) that are uniformly and vertically fixed on the adhesive resin (B). Is done.
According to a second aspect of the present invention, there is provided the electromagnetic wave shielding cushion material according to the first aspect, wherein the mesh substrate (A) is a bag, paper, a wire mesh, or a punching metal. Provided.
Furthermore, according to a third invention of the present invention, there is provided an electromagnetic wave shielding cushion material according to the first invention, wherein the conductive adhesive resin (B) is a conductive adhesive. .

According to a fourth invention of the present invention, there is provided an electromagnetic wave shielding cushion material according to the third invention, wherein the resin used for the conductive adhesive is an acrylic resin, an epoxy resin, or a urethane resin. Provided.
According to a fifth aspect of the present invention, there is provided the electromagnetic wave shielding cushion material according to the third aspect, wherein the conductive adhesive further contains a conductive filler.
Furthermore, according to a sixth aspect of the present invention, there is provided the electromagnetic wave shielding cushion material according to the fifth aspect, wherein the conductive filler is carbon black.

According to a seventh invention of the present invention, in the first invention, the conductive fiber (C) is a conductive material obtained by coating or kneading a conductive material on carbon fiber, metal fiber, or non-conductive fiber. An electromagnetic wave shielding cushion material is provided, which is an imparted fiber or a fiber made of a conductive polymer.
According to an eighth aspect of the present invention, in the seventh aspect, the conductive fiber (C) has a diameter of 1 mm or less, a length of 1 μm to 10 mm, and an aspect ratio of 10 to 1000. An electromagnetic wave shielding cushion material is provided.

On the other hand, according to the ninth aspect of the present invention, the first step of applying the conductive adhesive resin (B) on at least one surface of the network substrate (A), the adhesive resin (B) The second step of implanting conductive fibers (C) by electrostatic flocking on the surface of the adhesive resin (B), and the adhesive resin (B) is dried and cured while The method for producing an electromagnetic wave shielding cushion material according to any one of the first to eighth inventions, comprising a third step of fixing the conductive fiber (C) on at least one surface of the mesh substrate (A). Is provided.
Further, according to the tenth aspect of the present invention, in the ninth aspect, between the second step and the third step, further, conductive adhesion to the napped portion of the conductive fiber (C). The manufacturing method of the electromagnetic wave shielding cushion material characterized by apply | coating a conductive resin (B) is provided.

As described above, the present invention substantially fills the mesh of the mesh substrate (A) and the mesh substrate (A), and has a coating layer on at least one surface of the mesh substrate (A). Although it relates to an electromagnetic wave shielding cushion material comprising a conductive adhesive resin (B) to be formed and conductive fibers (C) fixed uniformly and vertically on the adhesive resin (B). The preferred embodiments include the following.
(1) In 3rd invention, the said conductive adhesive contains a conductive filler, The electromagnetic wave shielding cushion material characterized by the above-mentioned.

The electromagnetic wave shielding cushion material of the present invention substantially fills the mesh of the mesh substrate (A) and the mesh substrate (A), and coats at least one surface of the mesh substrate (A). A conductive adhesive resin (B) that forms a conductive fiber (C) that is uniformly and vertically fixed on the adhesive resin (B). Because of the low electrical resistivity while maintaining the structure, even if the processing accuracy of the electromagnetic shielding case connection part in the electronic device or the electronic device itself is insufficient, it follows the state of the mounting surface and obtains the electromagnetic shielding effect Can do. Also. Compared to conventional products, it is thinner and more cushioning. Furthermore, there is no difference in the conductive performance depending on the direction, it is isotropic, and it has stable conductivity with respect to the surface, the thickness direction, and the vertical and horizontal width directions.
Moreover, the manufacturing method of the electromagnetic wave shielding cushion material of this invention has few manufacturing processes, and can contribute to reduction of production cost and efficiency of production management. Furthermore, adjustment of the length and quantity of the conductive fiber (C) has an effect of enabling production of a highly versatile product in terms of thickness, performance, and cost.

Hereinafter, the present invention will be described in detail for each item.
The electromagnetic wave shielding cushion material of the present invention substantially fills the mesh of the mesh substrate (A) and the mesh substrate (A), and coats at least one surface of the mesh substrate (A). The conductive adhesive resin (B) that forms the conductive fibers and the conductive fibers (C) that are uniformly and vertically fixed on the adhesive resin (B).

1. Reticulated substrate (A)
In the electromagnetic wave shielding cushion material of the present invention, the mesh substrate (A) is made of a bag, a metal mesh (metal mesh), a punching metal, paper (carbon paper), and the like, and is conductive. The scissors and paper may be electroless plated scissors and paper. As long as the conductive fibers (C) can be implanted by electrostatic flocking on the mesh portion of the mesh substrate (A), other substrates can be used as appropriate. Among these, cocoons, paper, wire mesh (metal mesh), and punching metal are preferable.
Further, the shape of the mesh substrate (A) may be a sheet, a cylindrical shape, a knitted fabric or a non-woven fabric. The network substrate (A) may be a porous substrate or a foam, or a metal porous body obtained by performing metal plating on a woven fabric or the like.
Furthermore, the shape of the mesh portion of the mesh substrate (A) is appropriately set according to the shape of the conductive fibers (C) and the like.
Furthermore, the thickness of the mesh substrate (A) may be variously changed depending on the desired thickness of the electromagnetic shielding cushion material, but is preferably in the range of 0.05 to 5 mm.

2. Conductive adhesive resin (B)
In the present invention, the conductive adhesive resin (B) firmly bonds the mesh portion of the above-described mesh substrate (A) and the conductive fibers (C) planted therein to provide a conductive property. Any one having the above functions can be used as appropriate. Specifically, a conductive adhesive can be mentioned, for example.
Examples of the conductive adhesive include those obtained by adding a conductive filler to an acrylic, epoxy, or urethane resin adhesive that is usually used for flocking. As the conductive filler, metal (silver, gold, platinum, copper, nickel), metal oxide, amorphous carbon powder, graphite, silver-plated fine particles, and the like are used.
Moreover, in order to improve the electroconductivity of an adhesive agent, an electroconductive filler can also be added and used for an electroconductive adhesive agent. As the conductive filler, metal particles, carbon particles, and the like can be used as appropriate. From the viewpoint of conductivity and cost, carbon black, and among them, acetylene black using acetylene gas as a raw material is preferable.

3. Conductive fiber (C)
In the present invention, as the conductive fiber (C), carbon fiber, metal fiber, a fiber coated with a metal thin film, or a non-conductive fiber surface is coated or kneaded with electroless plating or a conductive substance to make conductivity. Examples thereof include fibers provided, conductive fibers made of a conductive polymer as a raw material, and those having a diameter of 1 mm or less, a length of 1 μm to 10 mm, and an aspect ratio of 10 to 1000 are preferable.

4). Electromagnetic wave shielding cushion material and method for producing the same The electromagnetic wave shielding cushion material of the present invention has a high electromagnetic shielding effect and can meet various demands, and can be easily obtained by the following production method.
The manufacturing method of such an electromagnetic wave shielding cushion material is:
(I) a first step of applying a conductive adhesive resin (B) on at least one surface of the network substrate (A);
(II) a second step of implanting conductive fibers (C) on the surface of the adhesive resin (B) by electrostatic flocking method while the adhesive resin (B) is not dried and cured; and
(III) a third step of drying and curing the adhesive resin (B) to fix the conductive fibers (C) on at least one surface of the network substrate (A);
It is characterized by containing.
Application of the conductive adhesive resin (B) in the first step can be performed by a general application method such as knife coater, roll coater, spray, dipping and the like.
Moreover, the electrostatic flocking method of a 2nd process can take the method currently performed normally.
Furthermore, the drying / curing method of the adhesive resin (B) in the third step can also employ a commonly performed method such as a heating method (60 to 80 ° C.).
By this production method, the conductive fibers (C) can be fixed and fixed to the network substrate.

Furthermore, in order to obtain the shape restoration effect of the napped conductive fibers (C) planted on the mesh substrate (A), the following steps are optionally performed.
(IV) A fourth step of applying a conductive adhesive resin (B) to the raised portions of the conductive fibers (C) between the second step and the third step;
Can be taken as appropriate. As a coating method in the fourth step, a general coating method, spraying, dipping, or the like can be employed.
An example of the electromagnetic shielding cushion material manufactured in this way is shown in FIG. 1 as a schematic cross-sectional view.

The electromagnetic wave shielding cushion material of the present invention is effective for effectively blocking electromagnetic waves leaking from electric / electronic devices or preventing the influence of external electromagnetic waves on the devices. Furthermore, this electromagnetic wave shielding cushion material has a napped shape planted by electrostatic flocking and is excellent in cushioning properties.
The conductive performance of the electromagnetic wave shielding cushion material of the present invention is an electric resistance value of 50 (Ω / □) or less, and the electromagnetic wave shielding performance is a performance of 20 (db) or more between 100 to 1000 MHz.

  Because of the above performance, the electromagnetic wave shielding cushion material of the present invention can effectively block electromagnetic waves leaking from an information equipment casing such as a mobile phone and protect electronic components that are relatively vulnerable to impact. For example, it can be suitably used as a mobile phone liquid crystal protective buffer material.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not particularly limited to these examples.

[Example 1]
The production method and performance evaluation method of the electromagnetic shielding cushion material of Example 1 are shown below.
First, the materials used will be described.
As the mesh substrate (A), a metal plate (copper plate 0.1 to 1 mm thickness or aluminum plate 0.1 to 1 mm having a diameter of 0.2 mm drilled into a 0.3 mm pitch in a lattice shape, for example Thickness) was used.
In addition, an acrylic adhesive containing nickel particles was used as the conductive adhesive as the conductive adhesive resin (B).
Furthermore, the electroconductive thin wire as the conductive fiber (C) was obtained by electroless plating (5 to 10%) of nickel on a polyester short fiber of about 0.1 to 2.0 mm.

Next, as a method for producing an electromagnetic shielding cushion material, a conductive adhesive is applied to a metal plate that has been punched with a knife coater and the like, while the conductive adhesive is not cured, by electrostatic flocking, The fine conductive wire was planted on a metal plate. Thereafter, the conductive adhesive was cured by heating at 60 to 80 ° C.
In this way, an electromagnetic wave shielding cushion material in which conductive thin wires were fixed in a raised shape on a metal plate could be obtained.

The conductivity of the obtained electromagnetic shielding cushion material was evaluated.
(I) Using a tester (two terminals), it was confirmed that the surface and the thickness direction had a conductivity of 1Ω or less.
(Ii) Using a Loresta resistance tester, it was confirmed that the surface resistance was 1 Ω or less.
It was also confirmed that the electromagnetic wave shielding performance by the KEC method was 20 (db) or higher.

[Examples 2 to 20]
In the same manner as in Example 1, the electromagnetic shielding cushion materials of Examples 2 to 20 were produced, and similarly the conductivity and electromagnetic shielding performance by the KEC method were evaluated and confirmed. Table 1 shows the types of these raw materials.

  As is clear from the results in Table 1 above, the electromagnetic shielding cushion materials obtained in Examples 1 to 20 are excellent in electrical conductivity and electromagnetic shielding performance, and have a good appearance.

It is a cross-sectional schematic diagram which shows the electromagnetic wave shielding cushion material of this invention.

Explanation of symbols

1 Reticulated substrate (A)
2 Conductive adhesive resin (B)
3 Conductive fiber (C)

Claims (10)

  A conductive adhesive resin that substantially fills the mesh of the mesh substrate (A) and the mesh substrate (A) and forms a coating layer on at least one surface of the mesh substrate (A). An electromagnetic wave shielding cushion material comprising (B) and conductive fibers (C) fixed uniformly and vertically on the adhesive resin (B).   2. The electromagnetic wave shielding cushion material according to claim 1, wherein the mesh substrate (A) is a bag, paper, a wire mesh, or a punching metal.   The electromagnetic shielding cushion material according to claim 1, wherein the conductive adhesive resin (B) is a conductive adhesive.   The electromagnetic shielding cushion material according to claim 3, wherein the resin used for the conductive adhesive is an acrylic, epoxy, or urethane resin.   The electromagnetic shielding cushion material according to claim 3, wherein the conductive adhesive further contains a conductive filler.   The electromagnetic shielding cushion material according to claim 5, wherein the conductive filler is carbon black.   The conductive fiber (C) is a carbon fiber, a metal fiber, a conductivity-imparting fiber obtained by coating or kneading a conductive material with a fiber having no conductivity, or a fiber made of a conductive polymer. The electromagnetic shielding cushion material according to claim 1.   The electromagnetic shielding cushion material according to claim 7, wherein the conductive fiber (C) has a diameter of 1 mm or less, a length of 1 μm to 10 mm, and an aspect ratio of 10 to 1000.   The first step of applying the conductive adhesive resin (B) on at least one surface of the mesh substrate (A), while the adhesive resin (B) is not dried and cured, the adhesive resin (B ) The second step of implanting the conductive fibers (C) on the surface by electrostatic flocking method, and the adhesive resin (B) is dried and cured to make the conductive fibers (C) a mesh substrate (A The method for producing an electromagnetic wave shielding cushion material according to any one of claims 1 to 8, further comprising a third step of adhering to at least one surface of (1).   The conductive adhesive resin (B) is further applied between the second step and the third step, on the raised portion of the conductive fiber (C). Manufacturing method of electromagnetic shielding cushion material.

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