JP2000059073A - Electromagnetic shielding transparent body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic shielding body which is high in transparency and electromagnetic shielding effect. SOLUTION: An adhesive layer 1 and a conductive layer are successively laminated on at least one surface of a transparent high-molecular film for the formation of a laminated film, the conductive layer of the laminated film is patterned, the laminated film whose conductive layer is patterned is pasted on a transparent high-molecular reinforcing body with an adhesive layer 2 for the formation of an electromagnetic shielding transparent body, wherein near-infrared cutting material and dye for correcting the near-infrared cutting material for color are divided in two and added to the adhesive layers 1 and 2, or are added to only to the adhesive layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a window on which a display surface of a display device, in particular, a plasma display (hereinafter abbreviated as PDP) which requires prevention of electromagnetic wave leakage and a medical device which needs to see through the inside are installed. And other surface cover materials.

[0002]

2. Description of the Related Art In recent years, with the rapid development of electronics, electromagnetic interference that causes malfunctions of electronic devices has become a serious problem with the development of computers and the like. As means for preventing the electromagnetic wave interference beforehand, there is an active shield that seals unnecessary radio waves at the source by making the housing of the electronic device conductive. As specific materials for preventing electromagnetic wave leakage, metal foils, punched metal foils, metal meshes, metal fibers, and organic / inorganic fiber plated materials are used. However, transparent materials are used for display bodies and windows represented by PDPs. Properties are absolutely necessary conditions, and none of them were suitable for use from the viewpoint of light transmission.

Further, since the metal surface is oxidized with the passage of time, high-frequency contact is easily cut off at lattice points even in a metal mesh which can be expected to have a certain degree of transparency, and the electromagnetic shielding effect is stable for a long time. There was a disadvantage that it was difficult to show. On the other hand, it has been considered that a composite oxide of indium oxide and tin oxide (hereinafter abbreviated as ITO), which is widely used as an electrode for liquid crystal and has no oxidative deterioration, is considered to be used, but it is pointed out that there is little electromagnetic wave leakage prevention function. In fact, it has been limited to antistatic function applications. Attempts have been made to increase the conductivity to the same level as that of metal, for example, 1 Ω / □ or less, but at present, even if the film is formed while heating on a glass substrate, the level is 4 Ω / □, and the film is formed on a plastic film. That was technically impossible.

Further, there is a problem of weight. In particular, if a large-sized and heavy glass substrate having a diagonal of 40 to 50 inches or more is used, which is attracting attention in the future, there is a problem from the viewpoint of mountability when mounting the PDP.
On the other hand, if a plastic substrate is used as a substrate for weight reduction, the most important means of heating the substrate to increase transparency and conductivity cannot be used from the viewpoint of heat resistance, and it is impossible to obtain a low resistance. Was. If the resistance is lowered by further increasing the film thickness, the film may be peeled off from internal stress after film formation due to the difference in the coefficient of linear expansion between the ITO film and the plastic substrate, or cracks may be formed to form ITO having a resistance as low as metal. Is 20-40
Ω was the limit, and it was impossible to achieve the purpose.

[0005]

SUMMARY OF THE INVENTION The present invention provides an inexpensive transparent electromagnetic wave shielding film having transparency and a high electromagnetic wave shielding effect, which is most suitable for a display, particularly for a plasma display or a window of a medical equipment room. To provide

[0006]

According to the present invention, there is provided an adhesive material comprising a transparent polymer film formed by patterning a conductive layer of a laminated film formed by sequentially laminating an adhesive layer 1 and a conductive layer on at least one surface. In the electromagnetic wave shielding transparent body bonded to the transparent polymer reinforcing body by the layer 2, the near-infrared cut material and a dye having a color correction relationship with respect to the near-infrared cut material are applied to the adhesive layers 1 and 2. It is an electromagnetic wave shielding transparent member divided or added only to the adhesive layer 2. In a preferred embodiment, the light transmittance at a wavelength of 550 nm is 50% or more, and the thickness of the transparent polymer reinforcement is 1%.
It is an electromagnetic wave shielding transparent body having a size of 5 mm to 5 mm. A more preferred embodiment is an electromagnetic wave shielding transparent body in which an antireflection layer and / or a hard coat layer is provided on at least one of the laminated film and the transparent polymer reinforcement.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer film in the transparent conductive film which is the most important substrate in the present invention includes polyester such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyimide, polycarbonate, polyacrylonitrile, and the like. It is made of a thermoplastic resin represented by polyethersulfone, polysulfone, polyetherimide, polyarylate, norbornene, a thermosetting resin represented by an ultraviolet curable resin, an epoxy resin or the like, and has a light transmittance at 550 nm of 80. % (Hereinafter, all values at 550 nm) or a copolymer of these polymers can be used and is appropriately selected.

Although it is desirable that the total light transmittance is as high as possible, the final product needs to be 50% or more. Therefore, even if at least two sheets are laminated, if the substrate has 80%, it is suitable for the purpose. Yes, since the higher the transmittance, the more layers can be laminated, the thickness is preferably 85% or more, most preferably 90% or more. Therefore, reducing the thickness is also an effective means. For example, the thickness of the polymer film is not particularly limited as long as transparency is satisfied, but is preferably 25 to 300 μm from the viewpoint of processability. Thickness 2
If the thickness is less than 5 μm, the film is too soft, and the film is easily stretched or wrinkled due to the tension at the time of forming or processing the oxide, which is a transparent conductive layer. On the other hand, if it exceeds 300 μm, the flexibility of the film decreases, and continuous winding in each step is difficult and not suitable. In particular, when laminating a plurality of sheets, the workability is significantly inferior, and the workability and 25 to 100 μm in consideration of the overall thickness.
m is particularly preferred.

When laminating the conductive layers, a known adhesive layer is provided for the purpose of improving the adhesion. This problem is particularly important when the conductive layer is patterned into fine wires. For example, when patterning is performed on an etching line, the adhesion between the base material and the conductive layer should be at least 0.3 k in order to withstand shower water pressure.
g / cm is required, and an adhesion force of 1.0 kg / cm or more is required as a level having no practical problem. If these adhesions are not obtained, the conductive layer may be peeled off after patterning, or may be disconnected during etching. Since a higher light transmittance is desired, the thickness of the adhesive layer, the refractive index of a substance used for the adhesive layer, and the like are also important characteristics. The type of adhesive can be selected as appropriate according to the base material to be used, but examples of synthetic resin-based adhesives include urea resin, melamine resin, phenol resin, epoxy resin, and vinyl acetate resin. Type, cyanoacrylate type, polyurethane type, α-olefin-maleic anhydride resin type, aqueous polymer-isocyanate type, acrylic resin type, UV curable resin type, emulsion type adhesive, hot melt type adhesive, synthetic There are a rubber-based adhesive, a silicone-based adhesive, and an inorganic-based adhesive.

The PDP emits light by using xenon gas discharge. The near-infrared ray generated at this time leaks to the outside and leads to malfunction of widely used sensors, so that the near-infrared ray cut function is indispensable for the front shield plate of the PDP. The necessary near-infrared region that needs to be shielded is 8
00 nm to 1100 nm, more preferably 800 nm to
The range is 1500 nm. 400nm to 800n
In the visible light region of m, it is necessary to maintain a sufficient light transmittance. However, a substance having a shielding function in the near-infrared region often absorbs also in the visible light region, and there is a problem that the material is transparent but looks colored. In the present invention, it has been found that in order to solve this problem of coloring, color correction is performed by adding a dye. The dye to be added is
It is not particularly limited as long as it has a dye, a pigment, and other substances having absorption in the visible light region, and several kinds of dyes may be added. The dye to be used can be selected from the near-infrared absorbing material to be used, the compatibility with the resin layer serving as a binder, and the solubility in a solvent. Examples of synthetic dyes include oil-soluble dyes and metal complex salt type organic dyes. Organic solvent-soluble dyes such as solvent-soluble dyes, disperse dyes, basic dyes, acid dyes such as metal complex dyes, reactive dyes, direct dyes, sulfur dyes, vat dyes, azoic dyes, mordant dyes, and complex dyes. As inorganic pigments, mica-like iron oxide, lead white, lead red, graphite, silver vermilion, ultramarine, navy blue, cobalt oxide, strontium chromate, zinc chromate, titanium dioxide, titanium yellow, titanium black, iron black, molybdenum, litharge, There are lithopone, and azo pigments, phthalocyanine blue and the like can be mentioned as organic pigments. The color created by the correction is preferably as close to colorless as possible, but can be arbitrarily selected in consideration of visibility, texture, and the like depending on the application of the transparent electromagnetic wave shield. In order to exhibit a near-infrared cut function, it is also possible to add several kinds of near-infrared cut materials having different wavelength regions to be cut.

When the near-infrared ray cut material and the dye are added as described above, it is difficult to add these materials to one coating layer if there is a difference in compatibility, dispersibility, appropriate solvent, and the like with the resin. Becomes Therefore, in such a case, if there are a plurality of layers to which the material is added, the degree of freedom in selecting the combination of the material and the resin layer is increased, and the function as the electromagnetic wave shielding transparent body can be improved. The present invention achieves this object by adding these materials to two adhesive layers indispensable for forming an electromagnetic wave shielding transparent body. Specifically, a near-infrared ray cut material and a color An adhesive layer 1 for providing a dye having a relationship to be corrected between the conductive layer and the film, and an adhesive layer 2 for bonding a laminated film formed by patterning the conductive layer to a transparent polymer reinforcement.
In addition, it was found that a transparent electromagnetic wave shielding body was prepared by dividing and adding. When both the near-infrared cut material and the color correction material are not sufficiently dissolved only in the adhesive layer 1, the adhesive layers 1 and 2 may be configured as resin compositions suitable for each. Also, some additives may dissolve in the same kind of adhesive layer but have low solubility in resin, and there is a problem that if only one layer is used to obtain the effect, the film thickness becomes extremely large. In this case, it is not necessary to increase the thickness of each layer more than necessary by adding it in two layers. The adhesive layer 1 may be exposed to an acid or alkali aqueous solution during the heating step for laminating the conductive layer and during the patterning process. At this time, the material whose properties are significantly deteriorated is divided into the adhesive layer 2. Alternatively, a near-infrared cut material and a color correction material can be added only to the adhesive layer 2.

In order to provide a near infrared cut function,
A method of adding a near-infrared cut function to the transparent polymer reinforcement and a method of newly establishing a coating layer are used, but the former is heat-resistant and solubility of the near-infrared cut material, etc.
Because of the constraints of the substrate manufacturing conditions,
In the latter case, the number of processes is newly increased, and there is a problem in cost. Therefore, this problem can be solved by providing the adhesive layer with a near-infrared cut function. Since the adhesive can be selected from a very wide variety of materials, it is easy to design the material based on the characteristics of the near infrared cut material to be used. In addition, since an adhesive material that is indispensable for maintaining the adhesion between the base material and the conductive layer has the function, there is no need to laminate a new coating layer. The amount of the near-infrared cut material added also depends on the thickness of the adhesive layer, but generally its function can be achieved with an amount of 1 wt% or less based on the resin solid content of the adhesive layer. The properties of the adhesive layer are not significantly changed by adding the cut material.
Examples of near-infrared absorbers include anthraquinone-based, aminium-based, polymethine-based, diimonium-based, cyanine-based dyes, palladium, nickel, platinum, molybdenum,
Metal complexes such as tungsten, and organic salts are included.

The colorant used for color correction can be selected from the compatibility with the near-infrared absorbing material used, the resin layer serving as a binder, and the solubility in a solvent. , Organic solvent-soluble dyes such as metal complex salt-type organic solvent-soluble dyes, disperse dyes, basic dyes,
There are acid dyes such as metal complex dyes, reactive dyes, direct dyes, sulfur dyes, vat dyes, azoic dyes, mordant dyes, and complex dyes. Silver vermilion, ultramarine, navy blue, cobalt oxide, strontium chromate, zinc chromate, titanium dioxide,
There are titanium yellow, titanium black, iron black, molybdenum, litharge, and lithopone, and examples of organic pigments include azo pigments and phthalocyanine blue.

As the conductive layer formed on the film, A
Metals such as u, Ag, Al, Pt, and Cu, or alloys and metal oxide films containing these as main components are used. Further, in addition to the above, oxides, nitrides, ITO and conductive polymers can be used instead, and these may be laminated as needed. Here, in the case of metal, the film thickness is 50
Å-50 μm is preferred. If it is less than 50 °, the shielding effect is extremely poor, and if it exceeds 50 μm, the pattern workability decreases and the transmittance decreases. Examples of the method for laminating the conductive layer include methods such as vapor deposition, sputtering, and ion plating, electroplating, laminating a metal foil, and a method using these in combination. In addition, as a method of forming an oxide or nitride containing ITO, a sputtering method is generally used, but a sol-gel method is also possible. When a conductive layer is formed by vapor deposition or electroplating, a pattern can be formed by a photolithography method, and when a conductive layer is formed by coating, a pattern can be formed by a printing method. When the conductive layer has a thickness of 1 μm or less, fine wire processing is easy, which is advantageous for improving light transmittance in pattern design, and when the conductive layer is 1 μm or more, the surface resistance value decreases. Therefore, it is effective in improving the shield characteristics. These can be designed according to the conductivity of the material to be used, the thickness of the conductive layer, the aperture ratio of the pattern, and the shape. What is necessary is just to select the film-forming method suitable for obtaining.

The frequency of the electromagnetic wave to be regulated is 10K
Since the range of Hz to 1000 MHz is generally used, the conductivity of the conductive layer requires a specific resistance of 10 ³ Ω · cm or less. Generally, the electromagnetic wave shielding effect is expressed by the following equation. S (dB) = 10log (1 / ρf) + 1.7t√f / ρ S (dB): Electromagnetic wave shielding effect ρ (Ω · cm): Volume resistivity of conductive film f (MHz): Electromagnetic wave frequency Naturally, shielding effect In order to increase S, it is necessary to reduce the specific resistance ρ as much as possible. The lower the specific resistance ρ, the more effectively electromagnetic waves having a wider range of frequencies can be effectively shielded. In order to obtain a desired shielding effect, it is possible to appropriately design the pattern shape, the material of the conductive layer, and the thickness of the conductive layer.

By forming the electromagnetic wave cut filter in this way, the shielding effect represented by the following equation can be greatly improved. S (dB) = 20 X log10 (E0 / E1) E0 is an incident electromagnetic wave E1 is a transmitted electromagnetic wave The allowable return loss, which is a conventional radio wave absorber, is a power absorption rate of 9
One guideline is 20 dB or more corresponding to 9% or more, but the present invention has enabled 30 to 50 dB.

The transparent polymer reinforcing plate withstands an external pressure and causes damage due to scratches and the like, and furthermore, lowers the transparency. A hard coat is indispensable. The hard coat layer is preferably made of an inorganic material, specifically a transparent oxide such as silicon oxide, alumina, titanium oxide or zirconium oxide, in addition to a resin such as epoxy acrylate or urethane acrylate.
Further, the original reinforcing plate needs to have a strength of 1 mm or more due to the use of a polymer in order to reduce the weight. As the thickness increases, the strength increases, but the weight and the transparency are disadvantageous. Therefore, if the strength can withstand artificial external pressure and finger pressure, the object can be achieved with 1 mm or more, and practically 5 mm Up to.

Further, it is desirable that the transparent polymer reinforcing plate has an antireflection function. This is installed in order to prevent diffuse reflection from the PDP on the display unit and increase contrast. Of course, the hard coat layer may have an anti-reflection function, and may be separately laminated.

[0019]

Example 1 A urethane-based adhesive layer 1 to which a near-infrared ray cut material was added was applied to a 75 μm-thick polyethylene terephthalate film (hereinafter abbreviated as PET), and both surfaces were roughened. A copper foil (12 μm thick) was laminated to obtain a PET film with a copper foil. This conductive layer was patterned by a photolithography method to obtain a mesh filter pattern having a line width of 10 μm and a space width of 160 μm. A hard coat with a pencil hardness of 3H or more having an anti-reflection function is applied to one surface of a 2 mm thick polycarbonate substrate, and a near red cut material (KAYASSOR manufactured by Nippon Kayaku)
B IRG-022) and an aliphatic polyester urethane (A manufactured by Toyo Morton Co., Ltd.) to which a dye (KAYASET Blue A-2R manufactured by Nippon Kayaku Co., Ltd.) having a color correction relationship is added.
D-N401) A patterned substrate was laminated on the back surface of the hard coat layer with the adhesive layer 2. At the outer edge, each transparent conductive film and the flat cable were bonded with silver paste (CRM-1085 manufactured by Sumitomo Bakelite) and electrically grounded.
The light transmittance at 550 nm as a transparent electromagnetic wave shield is 74%, and the light transmittance in the near infrared region is <10% (90%).
0 to 1200 nm), and the electric field shielding property is 200 to 10
50 dB or more in the range of 00 MHz (Advantest method)
And was good. The hard coat surface had a pencil hardness of 3H and was excellent in abrasion resistance. As a transparent plate for electromagnetic wave shielding for PDP, characteristics excellent not only in shielding property but also in durability were obtained.

<< Embodiment 2 >> In Embodiment 1, the adhesive layer 1 was used.
The kind of near-infrared cut material to be added to is made of aminium (KAYASORB IRG-022 manufactured by Nippon Kayaku),
A dye for correcting the coloring caused by this substance was added to the adhesive layer 2 and attached to the reinforcing plate. The light transmittance in the near infrared region of 900 to 1200 nm as a transparent electromagnetic wave shield was 10% or less, the light transmittance at 550 nm was 68%, and a transparent electromagnetic wave shield without coloring could be formed.

<< Embodiment 3 >> In Embodiment 1, a method for forming a conductive layer is as follows.
Electroplating was performed to reduce the copper thickness to 4 μm. The light transmittance at 550 nm as a transparent electromagnetic wave shield is 74%, and the light transmittance in the near infrared region is <10% (900 to 120).
0 nm), electric field shielding characteristics are 200-1000 MHz
In the range of 45 dB or more (Advantest method).

Comparative Example 1 A laminated film patterned in Example 1 without adding a dye for color correction to the adhesive layer 2 was attached to a reinforcing plate. 900-1200n
The light transmittance in the near infrared region of m is 10% or less and 550.
Although the light transmittance in nm was 68%, it was colored green due to the near-infrared cut material and could not be used as an electromagnetic wave shielding transparent body for PDP.

[0023]

According to the present invention, it is possible to provide a transparent electromagnetic wave shielding plate having excellent transparency.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a layer configuration according to a first embodiment.

Claims (5)

[Claims] An adhesive layer and a conductive layer are sequentially laminated on at least one side of a transparent polymer film, and a conductive layer of a laminated film is patterned and formed by an adhesive layer. In an electromagnetic wave shielding transparent body bonded to a body, a near-infrared ray cut material and a dye having a color correction relationship with respect to the near-infrared ray cut material are divided into an adhesive layer 1 and an adhesive layer 2, or 2. An electromagnetic wave shielding transparent body characterized in that it is added to only 2. 2. The light transmittance at a wavelength of 550 nm is 50%.
The electromagnetic wave shielding transparent body according to claim 1, which is as described above. 3. The thickness of the transparent polymer reinforcement is 1 mm to 5 m.
3. The electromagnetic wave shielding transparent body according to claim 1, wherein m is m. 4. The electromagnetic wave shielding transparent body according to claim 1, wherein an antireflection layer is provided on at least one of the laminated film and the transparent polymer reinforcing body. 5. The electromagnetic wave shielding transparent body according to claim 1, wherein a hard coat layer is provided on at least one of the laminated film and the transparent polymer reinforcing body.