JP2000013088A - Production of electromagnetic wave shield film, electromagnetic wave shield employing it and display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance electromagnetic wave shielding performance, transparency and nonvisibility by forming a geometric pattern of conductive paste by intaglio offset printing while setting the aperture at a specified value or above. SOLUTION: Recess of a plate is filled with a conductive paste composed of a metal, a metal oxide, irregular carbon powder, graphite and a metal plated conductive filler. The conductive paste is transferred temporarily to a blanket before being printed onto a transparent plastic support employing polyesters, e.g. polyethylene terephthalate or polyethylenenaphthalate. A geometric pattern combining a triangle, a square, a rectangle, a rhombus, and the like, is formed by such an intaglio printing while setting the aperture at 50% or above. According to the method, electromagnetic wave shielding performance, transparency and nonvisibility can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electromagnetic wave shielding film having a shielding property for electromagnetic waves generated from the front surface of a display such as a CRT, PDP (plasma), liquid crystal, EL, etc., an electromagnetic wave shielding body using the film, and a display. About.

[0002]

2. Description of the Related Art As a method of shielding electromagnetic wave noise generated from the front of a display such as a CRT or PDP, a method of forming a thin film conductive layer by depositing a metal or a metal oxide on a transparent substrate (Japanese Patent Laid-Open No. 1-278800). JP-A-5-323101). On the other hand, electromagnetic wave shielding materials in which good conductive fibers are embedded in a transparent base material (Japanese Patent Application Laid-Open Nos. 5-327274 and 5-26)
No. 9912) and an electromagnetic wave shielding material (see JP-A-62-57297 and JP-A-2-52499) in which a conductive resin containing metal powder or the like is directly printed on a transparent substrate. An electromagnetic wave shielding material in which a transparent resin layer is formed on a transparent substrate described above and a copper mesh pattern is formed thereon by electroless plating (see JP-A-5-283889) has been proposed.

[0003]

As a method for achieving both the electromagnetic wave shielding property and the transparency, Japanese Patent Application Laid-Open No. 1-278800 has been disclosed.
In the method of forming a thin film conductive layer by depositing a metal or metal oxide on a transparent substrate disclosed in Japanese Patent Application Laid-Open No. (100 ° to 2,000 °), the surface resistance of the conductive layer becomes too large, and the shielding effect of 30 dB or more, preferably 50 dB or more required at 30 MHz to 1 GHz, is insufficient at 20 dB or less. An electromagnetic wave shielding material in which a good conductive fiber is embedded in a transparent substrate (JP-A-5-327274, JP-A-5-269912)
In the publication, the electromagnetic wave shielding effect of 30 MHz to 1 GHz is 40 to 50 dB, but when the fiber diameter having no problem in visibility is 25 μm, the pitch required for regularly arranging the conductive fibers becomes 50 μm or less, The aperture ratio was reduced and the transparency was impaired, which was not suitable for display applications. Similarly, in the case of an electromagnetic wave shielding material in which a conductive resin containing a metal powder or the like disclosed in JP-A-62-57297 and JP-A-2-52499 is printed directly on a transparent substrate by a screen printing method or the like, the same applies. The line width was about 50 to 100 μm due to the limit of accuracy, and it was not suitable as a front filter because the transparency was reduced and the visibility of lines was exhibited. Further, in a shield material in which a transparent resin layer is formed on a transparent substrate such as polycarbonate described in JP-A-5-283889, and a copper mesh pattern is formed thereon by an electroless plating method, the adhesion of the electroless plating Therefore, there is a limitation that a step of roughening the surface of the transparent substrate is required in order to ensure the above, and that the substrate must not be damaged in the electroless plating step. Further, when the transparent substrate is thick, it cannot be brought into close contact with the display, and there has been a problem that leakage of electromagnetic waves from the transparent substrate increases. In addition, even if electromagnetic wave shielding and transparency could be achieved by this method, on the manufacturing side, the shielding material cannot be made into a scroll like an electromagnetic wave shielding tape, so that it becomes bulky and is not suitable for automation. As a result, there is a disadvantage that the manufacturing cost is increased.

[0004] With respect to the shielding property of electromagnetic waves generated from the front of the display, it is considered that the shielding property at 30 MHz to 1 GHz is 3
In addition to the electromagnetic wave shielding function of 0 dB or more, preferably 50 dB or more, the non-visual property is not only a good visible light transmittance and a large visible light transmittance but also a property that the presence of the shielding material cannot be confirmed with the naked eye. Sex is also required.
Until now, no satisfactory film has been obtained that sufficiently satisfies such characteristics as electromagnetic wave shielding, transparency, and invisibility. In view of the above, an object of the present invention is to provide an electromagnetic wave shielding film having electromagnetic wave shielding properties and transparency / invisibility, an electromagnetic wave shielding body and a display using the film.

[0005]

Means for Solving the Problems The inventors of the present invention have drawn an electromagnetic wave shielding film in which a geometric figure is drawn on a plastic film by an intaglio offset printing method with a conductive paste so that the aperture ratio becomes 50% or more. It has been found that the above problem can be solved. The invention according to claim 1 of the present invention provides an electromagnetic wave shielding film having an electromagnetic wave shielding property and transparency at a low cost, in a structure comprising a conductive paste and a transparent plastic support, wherein the conductive paste is an intaglio offset. This is a method of manufacturing an electromagnetic wave shielding film having a geometric figure drawn by a printing method and having an aperture ratio of 50% or more. The invention according to claim 2 of the present invention is to provide a conductive paste with metal plating to provide an electromagnetic wave shielding film having excellent electromagnetic wave shielding properties. According to a third aspect of the present invention, the conductive paste is a black paste in order to provide an inexpensive electromagnetic wave shielding film having excellent contrast. The invention according to claim 4 of the present invention is to blacken the metal plating on the conductive paste in order to provide an electromagnetic wave shielding film having excellent contrast. The invention according to claim 5 of the present invention provides an electromagnetic wave shielding film having excellent electromagnetic wave shielding properties, in which an intaglio offset printing method uses a conductive paste that is cured by ultraviolet (UV) or heat to a transparent plastic support. It includes a step of printing on top. The invention according to claim 6 of the present invention provides an electromagnetic wave shielding film having excellent electromagnetic wave shielding properties and transparency, in which the line width of a geometric figure drawn with a conductive paste is 40 μm or less, and the line interval is reduced. 10
The line thickness is set to 0 μm or more and the line thickness is set to 40 μm or less. The invention according to claim 7 of the present invention is to provide an electromagnetic wave shielding film having excellent electromagnetic wave shielding properties, the conductive filler forming the conductive paste is silver,
It is made of copper, nickel or an alloy containing any of them. The invention described in claim 8 of the present invention is to provide a transparent plastic support having a surface-treated transparent plastic support in order to provide an electromagnetic shielding film having excellent electromagnetic shielding properties. According to the ninth aspect of the present invention, in order to provide an electromagnetic wave shielding film having excellent electromagnetic wave shielding properties, at least one of a primer treatment, a plasma treatment and a corona discharge treatment is used for the surface treatment of the transparent plastic support. One or more methods are used. The invention according to claim 10 of the present invention uses a transparent plastic support made of a polyethylene terephthalate film or a polycarbonate film in order to provide an inexpensive electromagnetic wave shielding film having excellent workability. According to an eleventh aspect of the present invention, in order to provide an electromagnetic wave shield having an electromagnetic wave shielding property and transparency, the electromagnetic wave shield includes the above-mentioned electromagnetic wave shielding film and a plastic plate. According to a twelfth aspect of the present invention, any one of the above electromagnetic wave shielding films having electromagnetic wave shielding properties and transparency is used for a display. Alternatively, the electromagnetic wave shield according to claim 11 is used for a display.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As the conductive filler used for expressing the conductivity of the conductive paste of the present invention, metal, metal oxide, amorphous carbon powder, graphite, and metal-plated filler can be used. Metals include copper, aluminum,
Nickel, iron, gold, silver, platinum, tungsten, chromium,
Titanium, tin, lead, palladium and the like, stainless steel containing one or a combination of two or more thereof,
Alloys such as solder can also be used. Silver, copper or nickel is suitable in terms of conductivity, ease of printing, and price. On the other hand, when iron, nickel, and cobalt, which are paramagnetic metals, are used as the metal forming the conductive paste, it is possible to improve not only the electric field but also the magnetic field shielding property in particular. The shape of these metals and the like may be any of scaly, resinous, spherical, and irregular shapes, and can be treated with a lubricant or the like. The preferred particle size is 50 μm or less, and if the particle size is larger than this, the conductivity is reduced. The ratio of the metal in the conductive paste can be arbitrarily adjusted, but good shielding properties are exhibited when the content is 30% by weight or more, and more preferably 50% by weight or more.

[0007] Examples of the binder polymer of the conductive paste include the following. Natural rubber, polyisoprene, poly-1,2-butadiene, polyisobutene,
(Di) enes such as polybutene, poly-2-heptyl-1,3-butadiene, poly-2-t-butyl-1,3-butadiene, poly-1,3-butadiene, polyoxyethylene, polyoxypropylene , Polyvinyl ethyl ether, polyvinyl hexyl ether, polyethers such as polyvinyl butyl ether, polyvinyl acetate, polyesters such as polyvinyl propionate,
Polyurethane, ethylcellulose, polyvinyl chloride, polyacrylonitrile, polymethacrylonitrile, polysulfone, polysulfide, polyethyl acrylate, polybutyl acrylate, poly-2-ethylhexyl acrylate, poly-t-butyl acrylate, poly-3-
Ethoxypropyl acrylate, polyoxycarbonyl tetramethacrylate, polymethyl acrylate, polyisopropyl methacrylate, polydodecyl methacrylate, polytetradecyl methacrylate, poly-n-propyl methacrylate, poly-3,3,5-trimethylcyclohexyl methacrylate, polyethyl methacrylate, Poly (meth) acrylates such as poly-2-nitro-2-methylpropyl methacrylate, poly-1,1-diethylpropyl methacrylate, and polymethyl methacrylate can be used. Furthermore, epoxy acrylate, urethane acrylate, polyether acrylate, polyester acrylate, and the like can also be used as monomers copolymerizable with acrylic resin and other than acrylic. In particular, urethane acrylate, epoxy acrylate, and polyether acrylate are excellent from the viewpoint of adhesion to a support. Examples of epoxy acrylate include 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and allyl alcohol diacrylate. Glycidyl ether, resorcinol diglycidyl ether, diglycidyl adipate, diglycidyl phthalate, polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol tetraglycidyl ether, etc. (Meth) acrylic acid adducts. Polymers having a hydroxyl group in the molecule, such as epoxy acrylate, are effective for improving the adhesion to the support. In addition to these,
Phenol resin, melamine resin, epoxy resin, xylene resin, etc. can be applied, and these polymers may be copolymerized as needed, or two or more kinds may be blended and used. is there.

These binder polymers can be used by dissolving them in a general-purpose solvent or by stirring and mixing with a metal together with a metal dispersant without using any solvent. The composition used in the present invention, if necessary, in addition to the dispersant, a thixotropic agent, an antifoaming agent, a leveling agent, a diluent, a plasticizer, an antioxidant, a metal deactivator,
Additives such as coupling agents and fillers may be blended.

On the other hand, as a method of blackening the conductive paste, there is a method of adding a black pigment to a binder polymer or using a black additive such as carbon black. When carbon black is used as the black additive, a decrease in the conductivity of the conductive paste is preferably small. These black additives are usually based on 100 parts by weight of the binder polymer.
The addition of 0.001 part by weight or more can improve the contrast, but the addition of 0.01 part by weight or more is more preferable. Intaglio offset is suitable as a printing method used when drawing a geometric figure in the present invention. This is different from normal screen printing and lithographic offset printing,
This is because it is excellent in high-precision printability of 50 μm or less. The intaglio offset printing method is a method in which a conductive paste is filled in a concave portion of a plate, temporarily transferred to a blanket, and then printed on a transparent plastic support.

The geometric figures drawn with the conductive paste of the present invention include triangles such as equilateral triangles, isosceles triangles and right triangles, squares, rectangles, rhombuses, parallelograms, trapezoids and other quadrangles, and (positive). (Positive) n-gon, such as hexagon, (regular) octagon, (positive) dodecagon, (positive) decagon, circle, ellipse,
The pattern is a combination of stars and the like, and these units can be used alone or in combination of two or more. From the viewpoint of electromagnetic wave shielding, a triangle is most effective, but from the viewpoint of visible light transmission, if the number of (positive) n-gons is larger, the numerical aperture increases as the number of n increases. From the viewpoint, the aperture ratio needs to be 50% or more, and more preferably 60% or more. The aperture ratio is a percentage of the ratio of the area obtained by subtracting the area of the conductive paste of the geometric figure drawn with the conductive paste from the effective area to the effective area of the electromagnetic wave shielding film. When the area of the display screen is defined as the effective area of the electromagnetic wave shielding film, the display screen is a ratio that can be seen.

The line width of such a geometric figure is 40 μm.
m or less, line spacing is 100 μm or more, line thickness is 4
It is preferable that the thickness be in the range of 0 μm or less. Further, from the viewpoint of invisibility of the geometric figure, the line width is more preferably 25 μm or less, and the line interval is more preferably 120 μm or more and the line thickness is 18 μm or less from the viewpoint of visible light transmittance. The larger the line interval, the higher the aperture ratio and the higher the visible light transmittance, but the lower the electromagnetic wave shielding property. Therefore, the line width is preferably 1 mm or less. When the line interval is complicated by a combination of geometric figures and the like, the area is converted into a square area on the basis of a repeating unit, and the length of one side is set as the line interval.

By applying metal plating to the conductive paste used in the present invention, the electromagnetic wave shielding properties can be further improved. Either electrolytic plating or electroless plating can be used as a method for applying metal plating. The type of plating metal can be gold, silver, copper, nickel, aluminum, etc., but copper or nickel is most suitable in terms of conductivity and price. The range of the plating thickness is preferably from 0.1 to 100 μm, and if it is less than 0.1 μm, the conductivity is insufficient, so that sufficient shielding properties may not be exhibited. If the plating thickness exceeds 100 μm, the viewing angle becomes narrow, which is not preferable. 0.5-50
μm is more preferred.

Various surface treatments can be applied to the transparent plastic support to improve the printability of the conductive paste. As the method, treatment by applying a primer, plasma treatment, corona discharge treatment and the like are effective. It is necessary that the critical surface tension of the plastic support after the treatment is 35 dyn / cm or more by these treatments.
0 dyn / cm or more is more preferable. Critical surface tension is 35dy
If it is less than n / cm, the printability of the conductive paste decreases,
When forming a line width of 40 μm or less, ink spreading or bleeding occurs.

Examples of the transparent plastic support used in the present invention include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefins such as polyethylene, polypropylene, polystyrene and EVA, polyvinyl chloride and polyvinylidene chloride. Vinyl resin, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide,
It is preferable that the film is made of a plastic such as an acrylic resin and has a total visible light transmittance of 70% or more including colorless or colored and a thickness of 1 mm or less. These can be used as a single layer, or may be used as a multilayer film in which two or more layers are combined. Of these, transparency, heat resistance,
A polyethylene terephthalate film or a polycarbonate film is preferred in terms of ease of handling and price. The thickness of the plastic film is more preferably from 5 to 500 μm. If it is less than 5 μm, the handleability becomes poor,
If it exceeds 500 μm, the transmittance of visible light decreases.
10 to 200 μm is more preferred. Vacuum evaporation, sputtering, CV
Gold by D method, spray method, print printing method, etc.
Including silver, copper, aluminum, nickel, iron, cobalt, chromium, tin, titanium, and alloys thereof, or indium oxide, tin oxide, and mixtures thereof (hereinafter, ITO), titanium oxide, stannic oxide, and cadmium oxide Or a mixture thereof may be used to form a conductive thin film layer. Further, an anti-reflection layer, a near-infrared shielding layer may be formed or included on the outermost layer of the film or on the transparent plastic support. In addition, an adhesive layer may be provided at an arbitrary position, and an electromagnetic wave shielding film may be attached thereto or may be laminated with another layer.

The plastic plate used in the present invention is a plate made of plastic, specifically, a polystyrene resin, an acrylic resin, a polymethyl methacrylate resin,
Polycarbonate resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene resin, polypropylene resin, polyamide resin, polyamideimide resin, polyetherimide resin, polyetheretherketone resin, polyarylate resin, polyacetal resin, polybutylene terephthalate resin, polyethylene Thermoplastic polyester resin such as terephthalate resin, cellulose acetate resin, fluorine resin, polysulfone resin, polyethersulfone resin, polymethylpentene resin, thermoplastic resin such as polyurethane resin and diallyl phthalate resin, and thermosetting resin. Among these, a polystyrene resin, an acrylic resin, a polymethyl methacrylate resin, a polycarbonate resin, and a polyvinyl chloride resin having excellent transparency are preferably used. The thickness of the plastic plate used in the present invention is preferably 0.5 mm to 5 mm from the viewpoint of protection of the display, strength and handling.

[0016]

EXAMPLES Next, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. (Example 1) Polyethylene terephthalate (PET) film having a thickness of 50 µm (manufactured by Toyobo Co., Ltd., trade name A)
-4100) and a silver paste (Hitachi Chemical Industry Co., Ltd.) using an intaglio offset printing method on the easy-adhesion treated surface coated with a primer (trade name: HP-1, manufactured by Hitachi Chemical Co., Ltd., coating thickness: 1 μm). Lattice pattern (trade name: 25μ, Epimar EM-4500 manufactured by Co., Ltd.)
m, line interval (pitch) 250 μm). Thereafter, the conductive paste resin was heated and cured at 150 ° C. for 3 hours to produce an electromagnetic wave shielding film. The opening ratio of this film was 81%.

(Example 2) A polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., trade name: A-4100) having a thickness of 25 μm was used, and its primer (HP-1; trade name, manufactured by Hitachi Chemical Co., Ltd.) was used. Coating thickness 1μ
m) on the easy-adhesion treated surface coated with black dye (trade name, Nippon Kayaku Co., Ltd., Kayase
t BlackG) containing 0.5% by weight (trade name, manufactured by Hitachi Chemical Co., Ltd., Epimar EM-4500)
(Line width 20 μm, line interval (pitch) 286 μm) was formed. Thereafter, the paste resin was cured by heating at 160 ° C. for 2 hours. Electrolytic copper plating is applied to the completed silver paste grid pattern
An electromagnetic wave shielding film was prepared by forming a copper plating layer having a thickness of μm (electrolytic copper plating: for example, Printed Circuit Technology Handbook, edited by The Japan Printed Circuit Industry Association, Nikkan Kogyo Shimbun, February 28, 1987) Published, 470 pages). The opening ratio of this film was 86%.

(Example 3) A polycarbonate film (trade name, manufactured by Asahi Glass Co., Ltd., Lexan) having a thickness of 25 μm was used, and the corona-treated surface (critical surface tension: 54 dyn / cm) of the following photosensitivity was applied by intaglio offset printing. Grid pattern of conductive nickel paste containing nickel particles in conductive resin (line width 30 μm, line interval (pitch) 12
7 μm). Then, using an ultraviolet lamp,
The paste resin was irradiated with ultraviolet rays of 1 J / cm ² and further heated and cured at 120 ° C. for 60 minutes to produce an electromagnetic wave shielding film. The opening ratio of this film was 58%. (Composition of photosensitive resin) 2,2-Bis (4,4-N-malemicisylphenoxyphenyl) fluoro 30 parts by weight ethoxy equivalent 500 equivalents of a bisphenol A type epoxy resin and 1 equivalent of tetra-human perfluorophthalic anhydride in a nitrogen atmosphere Modified epoxy resin obtained by reaction at 150 ° C. for 10 hours at 45 ° C. 45 parts by weight of acrylonitrile-phthalic acid resin (PNR-1H, trade name of Nippon Synthetic Rubber Co., Ltd.) 20 parts by weight 1,3-bis (9,9-acrylicino) Nickel particles were dispersed in a 45% by weight varnish of heptane 5 parts by weight aluminum hydroxide 10 parts by weight cyclohexanone / methyl ethyl ketone (1/1 weight ratio) so as to be 30% by volume.

Example 4 A 50 μm thick PET film (trade name, A-4100, manufactured by Toyobo Co., Ltd.) was used and its primer (trade name, H, manufactured by Hitachi Chemical Co., Ltd.)
Epoxy / phenol resin containing 0.5% by weight of black pigment (trade name, Kayaset BlackG, manufactured by Nippon Kayaku Co., Ltd.) on the coated surface with easy adhesion by using intaglio offset printing method. Pattern (copper paste of Hitachi Chemical Co., Ltd., trade name of TBA-HME and trade name of Toto Kasei Co., Ltd., YD-8125 blended) of copper paste (line width 20 μm, line interval (pitch) 250 μm) Was formed. Then, at 150 ° C., 3
The paste resin was heat cured for a time. A 1 μm thick copper plating layer was formed on the lattice pattern of the completed copper paste by electroless copper plating (trade name, CUST-201, manufactured by Hitachi Chemical Co., Ltd.) to produce an electromagnetic wave shielding film. The opening ratio of this film was 84%.

Example 5 A 50 μm-thick PET film (trade name, manufactured by Toyobo Co., Ltd., A-4100) was used and its primer (trade name, manufactured by Hitachi Chemical Co., Ltd., H
P-1; coating thickness 1 μm) The carbon black (trade name, KETJEN BLACK EC-60, manufactured by Lion Corporation) is applied to the easily-adhesive treated surface by using intaglio offset printing.
0: an average particle size of 0.03 μm) and a lattice pattern (line width: 20 μm, silver paste (trade name, Epimar EM-4500, manufactured by Hitachi Chemical Co., Ltd.)) containing 1.0% by weight.
A line interval (pitch) of 250 μm was formed. Thereafter, the paste resin was cured by heating at 160 ° C. for 2 hours. A 5 μm-thick copper plating layer was formed by electrolytic copper plating on the lattice pattern of the completed silver paste to produce an electromagnetic wave shielding film. The opening ratio of this film was 84%.

Example 6 A commercially available acrylic plate (commercial glass made by Kuraray Co., Ltd., thickness of 3 mm) was applied to the electromagnetic wave shielding film obtained in Example 1 using a hot press machine.
And a commercially available soda lime glass having a thickness of 3 mm and an adhesive film (trade name, manufactured by Sekisui Chemical Co., Ltd.,
110 ° C., 20 kgf / cm through a thickness of 250 μm)
^2. Heat and pressure bonding was performed under the conditions of ² and 15 minutes to obtain an electromagnetic wave shielding structure.

Comparative Example 1 A grid pattern having a line width of 25 μm and a line interval (pitch) of 250 μm was formed using the conductive paste of Example 1 by screen printing instead of intaglio offset printing. However, many lines blurred, blurred, and disconnected.

(Comparative Example 2) A grid pattern similar to that of Example 1 was formed using the conductive paste of Example 1 and lithographic offset printing instead of intaglio offset printing. 25 μm due to bleeding
Could not be formed. The minimum printable line width was about 50 μm. Similarly, a 25 μm line width could not be formed by the letterpress offset printing method.

Comparative Example 3 In the same manner as in Example 1, a grid pattern having a line width of 45 μm and a line interval (pitch) of 125 μm was formed. Then, as in Example 1,
The paste resin was heated and cured at 150 ° C. for 3 hours to produce an electromagnetic wave shielding film. The aperture ratio of this film is 40
%Met.

Reference Example An electromagnetic wave shielding film was used in the same manner as in Example 1 using a polyimide film (trade name, Kapton, visible light transmittance 18%, manufactured by Du Pont-Toray Co., Ltd.) having a thickness of 25 μm as a transparent plastic support. Was prepared.

The electromagnetic wave shielding film obtained as described above, the conductive paste of the electromagnetic wave shielding body, or the aperture ratio of the geometric figure drawn by the conductive paste and the metal plating,
Abnormality of print pattern, electromagnetic wave shielding (300
MHz), visible light transmittance, invisibility, contrast, and adhesion to the acrylic plate after the heat treatment. Table 1 shows the measurement results.

The aperture ratio of the conductive paste or a geometric figure drawn by the conductive paste and the metal plating was actually measured based on a micrograph. The electromagnetic wave shielding property is measured using a coaxial waveguide converter (trade name, TWC-S-02, manufactured by Japan High Frequency Corporation).
The sample was inserted between the flanges of 4), and measured at a frequency of 300 MHz using a spectrum analyzer (trade name, manufactured by YHP, 8510B vector network analyzer). The visible light transmittance was measured using a double beam spectrophotometer (trade name, manufactured by Hitachi, Ltd., Model 200-10), and the average value of the transmittance at 400 to 700 nm was used.
The presence / absence, invisibility and contrast of the printed pattern were determined by visual observation. The invisibility is good when observing the electromagnetic wave shielding film from a place 0.5 m away and not recognizing the geometric figure formed of the conductive material.
Those that could be recognized were NG. Regarding the contrast, the electromagnetic wave shielding film was closely attached to the screen of the plasma display device, and the contrast was observed. Those having excellent contrast were evaluated as good, and those not being evaluated as NG. Regarding the adhesion of the film to the adherend, the sample was treated at 80 ° C. for 500 hours, and visually inspected for abnormalities such as blistering, peeling, and hue change.

[0028]

[Table 1]

In Comparative Example 1, an attempt was made to form a grid pattern with a line width of 25 μm and a line interval (pitch) of 250 μm by using a screen printing method, but many lines were blurred, blurred, and disconnected. In Comparative Example 2, pattern formation was attempted using the lithographic offset printing method and the letterpress offset printing method, and the minimum printable line width was 50 μm. Comparative Example 3 has a line width of 45
In this example, a grid pattern having a line spacing (pitch) of 125 μm was used, but the aperture ratio was only 40%. In the reference example, a polyimide film having a thickness of 25 μm was used as a transparent plastic support, and the visible light transmittance was 15% or less. For these comparative examples, shown in the examples of the present invention, in a structure composed of a conductive paste and a transparent plastic support, the conductive paste has a geometric figure drawn by intaglio offset printing, The electromagnetic wave shielding film having an aperture ratio of 50% or more had no line bleeding, blurring, or disconnection, and the minimum printable line width was as good as 20 μm or less. The electromagnetic wave shielding property is 30 dB or more in spite of the high aperture ratio and high brightness, and the electromagnetic wave shielding property can be made 50 dB or more by applying metal plating to a geometric figure drawn with a conductive paste. In addition, by performing the blackening process, the contrast is improved, and a clear image can be viewed.

[0030]

Since the electromagnetic wave shielding film obtained by the present invention is manufactured by using an intaglio offset printing method, it is possible to provide an electromagnetic wave shielding film having excellent electromagnetic wave shielding properties, transparency and invisibility at low cost. Is possible. By applying metal plating to the conductive paste according to claim 2, it is possible to provide an electromagnetic wave shielding film having extremely excellent electromagnetic wave shielding properties. Claim 3
By using the conductive paste described in (1) as a black paste, it is possible to provide an electromagnetic shielding film that is inexpensive and has excellent contrast. By subjecting the metal plating on the conductive paste according to claim 4 to blackening treatment, it is possible to provide an electromagnetic wave shielding film having excellent contrast. In the intaglio offset printing method according to the fifth aspect, by using a conductive paste that is cured by ultraviolet light (UV) or heat, an inexpensive and highly reliable electromagnetic wave shielding film can be provided. The geometric figure drawn with the conductive paste according to claim 6 has a line width of 4
By setting the line thickness to 0 μm or less, the line interval to 100 μm or more, and the line thickness to 40 μm or less, it is possible to provide an electromagnetic wave shielding film having excellent transparency and electromagnetic wave shielding properties. By providing the conductive filler forming the conductive paste according to claim 7 with silver, copper, nickel or an alloy containing any of them, it is possible to provide an electromagnetic wave shielding film having excellent transparency and electromagnetic wave shielding properties. it can. When the transparent plastic support according to claim 8 is a surface-treated transparent plastic support, an electromagnetic wave shielding film having excellent adhesion reliability can be obtained. An electromagnetic wave shielding film having excellent adhesion reliability is inexpensive by using at least one of a primer treatment, a plasma treatment, and a corona discharge treatment as the surface treatment method of the transparent plastic support according to claim 9. Can be obtained. By using a polyethylene terephthalate film or a polycarbonate film as the transparent plastic support according to claim 10, an electromagnetic wave shielding film having excellent transparency can be provided at low cost. By providing the electromagnetic wave shielding body composed of the electromagnetic wave shielding film according to claim 11 and a plastic plate, it is possible to provide a transparent electromagnetic wave shielding substrate. By using the electromagnetic wave shielding film or the electromagnetic wave shielding film having the electromagnetic wave shielding property and the transparency described in claim 12 for the display, a display that is lightweight, compact, has excellent transparency, and has little electromagnetic wave leakage can be provided.

When an electromagnetic wave shielding film is used for a display, the visible light transmittance is large and the invisibility is good, so that a clear image can be comfortably obtained under almost the same conditions as in a normal state without increasing the brightness of the display. Can be appreciated. The electromagnetic wave shielding film and the electromagnetic wave shielding body of the present invention are excellent in electromagnetic wave shielding property and transparency, so that, in addition to the display, the electromagnetic wave is generated, or the measuring device that protects from the electromagnetic wave, the inside of the measuring device and the manufacturing device. It can be used by providing it in a window or a case, especially in a site such as a window where transparency is required.

 ──────────────────────────────────────────────────の Continued on front page (72) Inventor Minoru Tosaka 1500 Oji Ogawa, Shimodate-shi, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. Inside the Shimodate Research Laboratory (72) Inventor Akashi Nakaso 48 Wadai, Tsukuba, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Tsukuba R & D Laboratories F-term (reference)

Claims (12)

[Claims] 1. A structure comprising a conductive paste and a transparent plastic support, wherein the conductive paste has a geometric figure drawn by intaglio offset printing, and has an aperture ratio of 50% or more. Method for producing an electromagnetic wave shielding film. 2. The method for producing an electromagnetic wave shielding film according to claim 1, wherein a metal plating is applied on the conductive paste. 3. The method for producing an electromagnetic wave shielding film according to claim 1, wherein the conductive paste is a black paste. 4. The method according to claim 1, wherein the metal plating on the conductive paste is blackened.
The method for producing an electromagnetic wave shielding film according to any one of the above. 5. An intaglio offset printing method using ultraviolet (U)
The method for producing an electromagnetic wave shielding film according to any one of claims 1 to 4, further comprising the step of: (V) printing a conductive paste which is cured by heat or on a transparent plastic support. 6. The electromagnetic wave according to claim 1, wherein the geometric figure drawn with the conductive paste has a line width of 40 μm or less, a line interval of 100 μm or more, and a line thickness of 40 μm or less. Manufacturing method of shield film. 7. The method for manufacturing an electromagnetic wave shielding film according to claim 1, wherein the conductive filler forming the conductive paste is silver, copper, nickel, or an alloy containing any of them. 8. The method for producing an electromagnetic wave shielding film according to claim 1, wherein the transparent plastic support is a surface-treated transparent plastic support. 9. The electromagnetic wave shield according to claim 1, wherein the surface treatment of the transparent plastic support uses at least one of a primer treatment, a plasma treatment and a corona discharge treatment. Film production method. 10. The method for producing an electromagnetic wave shielding film according to claim 1, wherein the transparent plastic support is a polyethylene terephthalate film or a polycarbonate film. 11. An electromagnetic wave shield comprising the electromagnetic wave shield film according to claim 1 and a plastic plate. 12. A display using the electromagnetic wave shielding film according to any one of claims 1 to 10 or the electromagnetic wave shielding body according to claim 11.