JP2010098019A - Electromagnetic wave shielding mesh - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave shielding mesh, which is excellent in corrosion resistance and antibacterial activity in addition to an electromagnetic wave shielding property and light transmissivity. <P>SOLUTION: The electromagnetic wave shielding mesh is woven in a mesh shape by using a Ti-coated Cu wire 50-500 μm in diameter as warp and weft. The electromagnetic shielding mesh has an aperture ratio of 70-90%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave shielding mesh that has good conductivity and efficiently shields electromagnetic waves, and has excellent corrosion resistance and antibacterial properties.

In recent years, cellular phones, plasma display panels (hereinafter referred to as PDP), etc. have rapidly spread, and malfunctions and communication failures of other electronic devices due to electromagnetic waves generated from these electronic devices have become problems. Yes. For this reason, it is important to shield electromagnetic waves generated from these electronic devices, but an electromagnetic shielding material that does not deteriorate the display image quality is also required.
As such an electromagnetic wave shielding material, as described in Patent Document 1, an electromagnetic wave shielding plate configured such that each conductive line pitch width of a mesh-like conductive pattern is sequentially different on a transparent electromagnetic wave shielding substrate surface. Is disclosed. However, since such an electromagnetic wave shielding plate is configured such that the pitch width of each conductive line is sequentially different, there is a difference in aperture ratio between a wide pitch portion and a narrow portion when a pattern is formed. There is a problem that spots appear on the brightness.
Further, as an electromagnetic wave shielding material that can avoid such a problem, a sheet-like electromagnetic wave shielding mesh such as a woven fabric as described in Patent Document 2 has been proposed. That is, the present invention is an electromagnetic shielding material having good workability and excellent shielding effect, and has a soft magnetic property and crystalline metal fibers mainly composed of iron and copper (hereinafter referred to as Cu). It is said that it is a sheet-like electromagnetic shielding material containing at least a conductive filament such as aluminum (hereinafter referred to as Al). However, since such an electromagnetic shield sheet uses crystalline metal fibers mainly composed of iron, there is a problem that the corrosion resistance is insufficient and it cannot be used in a corrosive environment.
Furthermore, when the electromagnetic wave shielding mesh produced by giving a yarn density difference at a specific ratio to the warp yarn and weft yarn density as described in Patent Document 3 is arranged on the front surface of the display body In addition, the leakage of electromagnetic waves can be effectively shielded without causing moire or brightness spots. In addition, regarding the yarn, it is described that a yarn having a conductive metal film formed on the surface thereof such as a synthetic fiber or a conductive metal fiber is used. However, in order to perform metal plating on synthetic fibers, it is necessary to use a large amount of chemicals, so it is necessary to treat waste liquid, and there is a concern about the problem of environmental pollution. In addition, when a fiber using silver (hereinafter referred to as Ag) plating is used as a synthetic fiber, Ag reacts with hydrogen sulfide (hereinafter referred to as H ₂ S) in the air when the electromagnetic shielding mesh is used in a portion where the wind is applied. There is a problem in corrosion resistance such as silver sulfide (hereinafter referred to as Ag ₂ S), and the conductivity is lowered and the shielding effect is lowered. Furthermore, even when using metal fibers, there is a problem in corrosion resistance such as discoloration when copper fibers having good conductivity are used.
Japanese Patent Laid-Open No. 11-121978 JP-A-5-267883 JP 2008-10701 A

  Therefore, the problem to be solved by the present invention is to provide an electromagnetic wave shielding mesh that is excellent in electromagnetic wave shielding properties and light transmission properties, and particularly excellent in corrosion resistance and antibacterial properties.

  The problem to be solved is an electromagnetic wave in which a titanium-coated copper wire (hereinafter referred to as a Ti-coated Cu wire) having a diameter of 50 to 500 μm is used as warp and weft as described in claim 1 and is woven into a mesh shape. This is solved by using a shielding mesh.

  Further, as described in claim 2, the electromagnetic wave shielding mesh according to claim 1 is solved by setting the aperture ratio of the electromagnetic wave shielding mesh to 70 to 90%.

  Since the present invention as described above is an electromagnetic wave shielding mesh in which a Ti-coated Cu wire having a diameter of 50 to 500 μm is woven into a mesh shape as warp and weft, it has excellent workability and uses a copper wire inside. It has good conductivity and excellent electromagnetic shielding properties, and has a titanium coating layer on the outside, so that it has excellent corrosion resistance and antibacterial properties. Moreover, since the titanium-coated copper wire having a specific diameter is woven in a mesh shape as warp and weft, the aperture ratio (area ratio of the portion where no Ti-coated Cu wire is present in the unit area) can be determined relatively freely. Therefore, an electromagnetic shielding mesh excellent in light transmittance can be obtained. Furthermore, the woven electromagnetic shielding mesh can be washed and cleaned.

  In addition, by setting the aperture ratio of the electromagnetic wave shielding mesh to 70 to 90%, in addition to the above-described effects, the electromagnetic wave shielding mesh has sufficient light transmittance, so that spots due to the brightness of the screen do not occur. It is useful as an electromagnetic shielding material for mobile phones and PDPs.

  Embodiments of the present invention will be described below. The present invention is an electromagnetic wave shielding mesh in which a Ti-coated Cu wire having a diameter of 50 to 500 μm is used as warp and weft and is woven into a mesh shape. This will be described in detail below.

As described above, the electromagnetic shielding mesh obtained by weaving warp and weft into a mesh shape is relatively easy to process, and the aperture ratio of the electromagnetic shielding mesh can be freely selected. There is. For this reason, an electromagnetic shielding mesh using wefts and warps made of a conductive material has been proposed, but there are various problems depending on the material used. For example, when a fiber using Ag plating is used as the synthetic fiber, Ag reacts with H ₂ S in the air to form Ag ₂ S when the electromagnetic wave shielding mesh is used in a portion where the wind is applied. There is a problem that the shielding effect deteriorates due to lowering. Therefore, corrosion resistance of such Ag 2 _S is not generated is determined. Furthermore, when Cu fibers having good conductivity are used, there is a problem in corrosion resistance such as discoloration of the Cu fiber surface. Further, when Ti wire or stainless steel (SUS) wire is used, corrosion resistance is good but conductivity is low, so that reflection of electromagnetic waves on the surface of the shielding material is reduced, and shielding properties are considered to be poor. Therefore, in the present invention, these problems were solved by using Ti-coated Cu wire having a specific thickness as the warp and weft of the electromagnetic wave shielding mesh as shown in FIG.

FIG. 1 (c) shows a schematic cross section of the Ti-coated Cu wire of the present invention. Reference numeral 1 denotes a Ti-coated Cu wire, and a Ti coating layer 3 is provided on the Cu wire 2. 1A is a schematic plan view in which a part of the electromagnetic wave shielding mesh is enlarged, and FIG. 1B is a schematic cross-sectional view thereof.
By using the Ti-coated Cu wire 1 as in the present invention, sufficient conductivity is ensured by the central Cu wire 2 to have an electromagnetic shielding effect, and corrosion resistance is simultaneously secured by the Ti coating layer 3 coated thereon. The That is, it reacts with H ₂ S to become Ag ₂ S as in the case where Ag is used by the Ti coating layer 3, and the conductivity is lowered and the shielding effect is lowered, or the color changes when Cu fibers are used. There is no problem. More specifically, the above problem does not occur even when used in a corrosive environment such as the sea. Furthermore, an electromagnetic shielding mesh having antibacterial properties can be obtained by the Ti coating layer 3. In addition, it is not preferable from the point of electroconductivity that the Ti coating | coated Cu wire 1 makes the Ti coating layer 3 too thick from the need of ensuring sufficient electromagnetic wave shielding effect. The cross-sectional coverage is preferably 30% or less. With such a coverage, the corrosion resistance can be sufficiently secured.
And said Ti covering Cu wire 1 is made to run, for example, while forming Ti covering material in the shape of a pipe with an extrusion molding machine etc., and simultaneously forming Cu material in the shape of a line with an extrusion molding machine etc. It can be obtained by inserting a Cu wire into the wire, bringing them into close contact with each other by drawing, and processing them into a Ti-coated Cu wire having a diameter of 50 to 500 μm.

  Moreover, by setting the diameter of the Ti-coated Cu wire 1 to 50 to 500 μm, it is possible to freely select the aperture ratio (area ratio of the portion where the Ti-coated Cu wire does not exist in the unit area) when weaving the electromagnetic shielding mesh. This is preferable in order to ensure sufficient electromagnetic shielding properties. That is, the aperture ratio (light transmittance) and the electromagnetic wave shielding property of the electromagnetic wave shielding mesh are determined by the diameter and pitch of the Ti-coated Cu wire, and the electromagnetic wave shielding property is improved if the diameter of the Ti-coated Cu wire is large. The permeability will be reduced. On the contrary, by increasing the pitch, the light transmittance can be improved, but the electromagnetic wave shielding property is lowered. Therefore, in order to make it easy to manufacture an electromagnetic shielding mesh that satisfies both the aperture ratio (light transmittance) and the electromagnetic shielding properties when weaving into the electromagnetic shielding mesh, the diameter of the Ti-coated Cu wire 1 is set to 50 to 500 μm. Should do. That is, when the diameter is less than 50 μm, when weaving the electromagnetic wave shielding mesh, the Ti-coated Cu wire is easily kinked and may be damaged. In addition, when the Ti-coated Cu wire 1 having a diameter exceeding 500 μm is used, the light transmittance is deteriorated, and the screen may be darkened when arranged on the front surface of the display body. Further, when the aperture ratio is increased, the electromagnetic wave shielding effect is deteriorated.

  Therefore, it was confirmed that by using the Ti-coated Cu wire 1 as an electromagnetic wave shielding mesh (FIG. 1a) having an aperture ratio of 70 to 90%, both light transmittance and electromagnetic wave shielding properties can be satisfied. . That is, when the aperture ratio is less than 70%, the light transmission is not sufficient, and there is a problem that the screen becomes dark when arranged on the front surface of various display bodies. In addition, if it exceeds 90%, the electromagnetic wave shielding effect is not sufficient and there is a problem. Furthermore, an electromagnetic wave shielding mesh having an aperture ratio of 70 to 90% can be obtained by weaving (woven fabric) Ti-coated Cu wire having a diameter of 50 to 500 μm as warp and weft. Although the case of plain weave is described in FIGS. 1A and 1B, other weaving methods and knitted fabrics may be used. In short, by combining Ti coated Cu wire 1 with a diameter in the range of 50 to 500 μm as warp and weft and weaving into an electromagnetic shielding mesh with an aperture ratio of 70 to 90%, it is excellent in electromagnetic shielding and light transmission. In addition, an electromagnetic wave shielding mesh having particularly excellent corrosion resistance and antibacterial properties can be obtained.

The effects of the present invention will be described below by describing examples and comparative examples.
Various Ti-coated Cu wires having a diameter of 25 to 700 μm were produced by a conventional method. A mesh having the structure shown in Table 1 was produced by plain weaving using the obtained Ti-coated Cu wire with a diameter of 25 to 700 μm as warp and weft. Here, Ti-coated Cu wires having the same diameter were used for the warp and the weft, and the opening ratio of the mesh was variously changed by adjusting the density of the warp by the weave of the loom. Of course, the aperture ratio can be changed by using warp and weft having different diameters. The electromagnetic wave shielding mesh thus obtained was examined for aperture ratio, corrosion resistance, visible light transmittance, and shielding characteristics.
The aperture ratio (area ratio of the portion where the Ti-coated Cu wire does not exist in the unit area) was calculated by obtaining the diameter and pitch of the Ti-coated Cu wire.
For corrosion resistance, perform a salt spray test (JIS Z 2371) at a temperature of 35 ° C. for 24 hours, and pass the test that does not show discoloration or dissolution on the surface after the test required by the mobile phone manufacturer. What was not satisfied was described by x mark.
Visible light transmittance was measured using a spectrophotometer (U-4100) manufactured by Hitachi High-Tech. Those having a transmittance of 80% or more were regarded as acceptable.
About the shielding property of electromagnetic waves, it evaluated by KEC method (MIL-STD283 which is a standard measurement method of Kansai Electronics Industrial Promotion Center). That is, a sample mesh is held at a predetermined position in a shield box where an oscillation antenna and a reception antenna are installed at a short distance, and the oscillation is performed by changing the frequency in the range of 100 KHz to 1 GHz, and attenuation at the angular frequency at that time The state was measured with a spectrum analyzer (R3361A manufactured by Advantest). If the attenuation amount at each frequency was 30 db or more, it was judged good. A case where all of these test items pass is designated as a comprehensive evaluation 〇 mark. If any item fails, it is marked with a cross. The results are shown in Table 1.

As is clear from Examples 1 to 5 shown in Table 1, the electromagnetic wave shielding woven in a mesh shape so that the opening ratio is 70 to 90% using Ti-coated Cu wire having a diameter of 50 to 500 μm as warp and weft. It can be seen that an electromagnetic wave shielding mesh satisfying all of the corrosion resistance, the visible light transmittance, and the shielding characteristics can be obtained by using the mesh.
That is, as described in Examples 1 and 2, an electromagnetic wave shielding mesh woven using a Ti-coated Cu wire having a diameter of 50 μm so that the aperture ratio is 70 to 90% is corrosion resistance and visible light transmittance. It can also be seen that it has excellent shielding properties. Moreover, as described in Examples 4 and 5, it can be seen that an electromagnetic shielding mesh woven using a Ti-coated Cu wire having a diameter of 500 μm so that the aperture ratio is 70 to 90% is also excellent. . Furthermore, as described in Example 3, an electromagnetic shielding mesh woven using a Ti-coated Cu wire having a diameter of 250 μm so that the aperture ratio was 80% was also excellent.

On the other hand, as shown in Comparative Example 1, an electromagnetic wave shielding mesh woven using a Cu wire having a diameter of 500 μm as a wire has a severe surface discoloration due to a salt spray test (JIS Z 2371) and fails corrosion resistance. became. Further, as in Comparative Example 2, even when a Ti-coated Cu wire was used, if the diameter was 25 μm, it could not be woven into the target mesh. For this reason, the measurement of the aperture ratio, corrosion resistance, visible light transmittance, and shielding properties were not evaluated. Further, as shown in Comparative Examples 5 and 6, when the mesh was woven using a thick Ti-coated Cu wire having an outer diameter of 700 μm, the opening ratio was 70% and 90%, which was within the scope of the present invention. However, the transmittance was rejected as less than 80%. This is presumably because even when the aperture ratio is the same, if the diameter of the Ti-coated Cu wire is large, the electromagnetic wave shielding mesh becomes thick and the transmitted light decreases.
Further, as in Comparative Example 3, even when the outer diameter of the Ti-coated Cu wire is 300 μm and the range of the present invention is used, if the aperture ratio is as small as 50%, the shielding property is passed. The transmittance was rejected as 70%. Further, as in Comparative Example 4, even if the outer diameter of the Ti-coated Cu wire is 500 μm and within the range of the present invention, if the aperture ratio is increased to 95%, the transmittance is passed but the shielding property is achieved. Was rejected at 25db.

  INDUSTRIAL APPLICABILITY The present invention is useful as an electromagnetic wave shielding mesh that is excellent in shielding properties (electromagnetic wave shielding properties) and light transmittance as an electromagnetic wave shielding mesh used for mobile phones, PDPs, and the like, and particularly excellent in corrosion resistance.

(A) is a schematic plan view showing a part of the electromagnetic wave shielding mesh of the present invention, (b) is a schematic cross sectional view showing a cross section of (a), and (c) is a view of a Ti-coated Cu wire used for the electromagnetic wave shielding mesh. It is the schematic which shows a cross section.

Explanation of symbols

1 Ti coated Cu wire 2, Cu wire 3 Ti coated layer

Claims (2)

  An electromagnetic wave shielding mesh characterized in that a titanium-coated copper wire having a diameter of 50 to 500 μm is woven in a mesh shape using warp and weft.   The electromagnetic wave shielding mesh according to claim 1, wherein the electromagnetic wave shielding mesh has an aperture ratio of 70 to 90%.

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