JP4237996B2 - Light transmissive electromagnetic shielding sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a public facility, a hall, a hospital, a school, a corporate building, a laboratory, a precision parts manufacturing factory, an electromagnetic shielding room, or other building windows that require electromagnetic shielding (shielding), or an electric product that generates electromagnetic waves. The present invention relates to an electromagnetic wave shielding sheet that can be seen through and used for a character / image display portion.
[0002]
[Prior art]
Conventionally, as a light-transmitting electromagnetic wave shielding sheet having both light shielding properties and electromagnetic wave shielding properties, the following can be cited mainly for display applications.
[0003]
(1) A vacuum film-formed product in which a highly conductive metal such as gold is formed on a transparent substrate such as a resin sheet by vacuum deposition or the like, and a transparent conductive thin film is provided on the entire surface.
(2) An etched product in which a conductive metal foil made of copper or the like is laminated on a transparent substrate and then etched using a photolithography method to form a resist pattern to form a patterned metal layer (Patent Document 1) Etc.).
[0004]
Moreover, regarding the ground portion of the light-transmitting electromagnetic wave shielding sheet, for example, the following techniques can be cited.
[0005]
(3) When the conductive metal foil laminated on the transparent base material is patterned by etching into the metal layer with the etched product of (2) above, the portion to be light transmissive is etched using a black resist. As will be described later, a mask layer is provided at the end of the sheet, and after etching, the mask layer is removed to expose the metal layer (see Patent Document 2).
(4) After etching the conductive metal foil laminated on the transparent substrate with an adhesive layer in the etched product of (2) above to form a metal layer by etching, the etching resist is completely removed and the metal is removed. After the layer is exposed, the transparent substrate and the adhesive layer around the sheet are further removed with a laser or the like, and only the metal layer is exposed on the front and back in a frame shape to form a ground portion (see Patent Document 3). .
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-41682
[Patent Document 2]
JP-A-9-293898 ([Claim 2], [0027] to [0036], FIG. 6, FIG. 7)
[Patent Document 3]
JP 2001-53488 A ([0011], [0031])
[0007]
[Problems to be solved by the invention]
However, the conventional light-transmitting electromagnetic wave shielding sheets as described in the above (1) to (4) have the following drawbacks.
[0008]
The vacuum film-formed product of the conductive thin film (1) is inferior in the electromagnetic wave shielding performance in the GHz band, and cannot sufficiently shield the electromagnetic wave generated from the device and the electromagnetic wave from the device having the high frequency band used. Moreover, the gloss peculiar to metal vapor deposition appears, and this is disliked in the appearance in the window use etc. of a building.
The etched product of the above (2) solves the problem that the electromagnetic wave shielding performance which is a problem in (1) is inferior. Further, the resist for patterning the metal layer is removed after the etching, so that the metal layer is exposed, so that the ground can be easily taken. However, as it is, the metallic luster of the metal layer such as copper appears, and the visibility of the display is lowered in the display application. Therefore, the surface of the metal layer is blackened. However, if the metal layer is exposed, it is easily damaged and a layer for protecting the surface must be provided separately.
[0009]
In this respect, in the grounding technique of (3) above, the metal layer exposes the portion to be grounded and the black resist is left on the metal layer in the portion to be light transmissive, so that the metallic luster can be prevented and the surface can also be prevented. Protected. However, apart from the resist for pattern formation, a mask layer needs to be formed and further removed, which complicates the production process.
Further, in the grounding technique (4), since the metal layer around the sheet is used as it is as the ground part, a removal process for removing the transparent base material or the like with a laser is required, and the production process becomes complicated.
[0010]
That is, the subject of this invention is making it easy to take earth | ground with light transmittance and electromagnetic wave shielding performance as what can be applied also to the window etc. of a building about a light transparent electromagnetic wave shielding sheet.
[0011]
[Means for Solving the Problems]
Therefore, in order to solve the above-described problems, in the light-transmitting electromagnetic wave shielding sheet of the present invention, a patterned metal layer is laminated on a transparent substrate via an adhesive layer, and a resist is further formed on the pattern of the metal layer. In the light-transmitting electromagnetic wave shielding sheet in which layers are laminated, the resist layer is formed of a conductive resist layer containing conductive particles, and the conductive resist layer is formed in contact with the metal layer.In both cases, the particle diameter of the conductive particles is larger than the thickness of the conductive resist layer.The configuration.
[0012]
By adopting such a configuration, even if the metal layer is covered with a resist layer, the resist layer is a conductive resist layer having conductivity, so that the conductive resist layer is formed from the surface of the light-transmitting electromagnetic wave shielding sheet. It can be electrically connected to the metal layer via the wire, and can be easily grounded. Therefore, for example, electrical connection with a window frame such as an aluminum sash is facilitated during construction.Moreover, by forming the conductive resist layer in such a thickness that the particle size of the conductive particles is larger than the thickness of the conductive resist layer, the conductive particles are between the metal layer and the outside of the metal frame, Conductivity is obtained by creating a bridge.
[0013]
The light-transmitting electromagnetic wave shielding sheet of the present invention has a configuration in which the conductive resist layer is formed on the entire surface including the sheet center and the sheet edge in the above-described configuration.
[0014]
With such a configuration, the conductive resist layer can be simply transmitted through a light, because the conductive resist is used as a resist for patterning the metal layer by etching and only remains after etching. The electromagnetic wave shielding sheet.
[0015]
Alternatively, in the light transmissive electromagnetic wave shielding sheet of the present invention, the conductive resist layer is formed only at the end of the sheet, and the resist layer at the center of the sheet is formed with a non-conductive resist layer. The configuration.
[0016]
In such a configuration, the resist layer at the center of the sheet, which is the main surface of the light-transmitting electromagnetic wave shielding sheet, is a non-conductive resist layer that does not require consideration of conductivity. Specifications that emphasize various durability required for application to building windows and the like such as weather resistance, heat resistance, water resistance, and moisture resistance become easy.
[0017]
In each of the above structures, it is preferable to contain conductive carbon particles as the conductive particles of the conductive resist layer.
With such a configuration, the color of the conductive resist layer can be made black, and the pattern can be made inconspicuous even if the conductive resist layer is provided at the center of the sheet.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0019]
〔Overview〕
In the sectional view and the plan view of FIG. 1, two examples of the form of the light transmissive electromagnetic wave shielding sheet 10 of the present invention are shown. A light-transmitting electromagnetic wave shielding sheet 10 according to the present invention has a basic configuration in which a patterned metal layer 2 made of copper foil or the like is laminated on an adhesive layer 3 on a transparent substrate 1 made of a polyethylene terephthalate sheet or the like. Further, the resist layer 4 is laminated on the pattern of the metal layer 2, and for this configuration, a conductive resist layer 4A containing conductive particles such as conductive carbon particles is used as the resist layer 4. The conductive resist layer 4A can be grounded.
The light-transmitting electromagnetic wave shielding sheet 10 illustrated in the cross-sectional view of FIG. 1A and the plan view of FIG. 1B is a configuration example in which a conductive resist layer 4A is formed over the entire surface, and FIG. The light-transmitting electromagnetic wave shielding sheet 10 illustrated in the sectional view of FIG. 1 and the plan view of FIG. 1D is formed only at the sheet end portion where the conductive resist layer 4A is the ground portion, and the resist layer at the center portion of the sheet is usually used. This is a configuration example in which a non-conductive resist layer 4B is formed.
Note that a resist layer such as a conductive resist layer or a non-conductive resist layer is a preferable configuration in that the resist layer can be made inconspicuous when it is dark, such as black or amber.
[0020]
Hereinafter, the present invention will be described in detail step by step for each layer.
[0021]
(Transparent substrate)
As a raw material of the transparent substrate 1, a resin material such as a transparent thermoplastic resin or a thermosetting resin can be used. However, a thermoplastic resin is more preferable than a thermosetting resin in terms of flexibility desired at the time of manufacture and enforcement in a roll form. Examples of the thermoplastic resin include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acrylic resins, polycarbonate resins, polyolefin resins such as polypropylene, polyethylene, polybutene, and polymethylpentene, or triacetyl cellulose and diacetyl cellulose. Such as cellulose resin, polyvinyl chloride resin, polyamide resin, polystyrene resin, polyurethane resin, polysulfone resin, polyether resin, polyacrylonitrile resin, and the like. Among these, polyethylene terephthalate is the most preferable resin in terms of transparency, heat resistance, chemical resistance, cost, and the like.
[0022]
As the transparent substrate, a single layer sheet or a laminate sheet of two or more layers made of a single substance or a mixture of two or more of these resins can be used.
The thickness of the transparent substrate is not particularly limited as long as it depends on the application, but is usually 25 to 350 μm, preferably 50 to 150 μm. If the thickness is less than 50 μm, there is no stiffness (waist), and workability at the time of enforcement is reduced. In addition, when using a sheet of less than 50 μm, such as polyethylene terephthalate, it may be used as a laminated sheet that is laminated with another sheet (for example, a polyethylene terephthalate sheet with a heat ray cut function, a hard coat polyethylene terephthalate sheet) to increase the thickness. . On the other hand, even if the thickness exceeds 150 μm, if it is a highly transparent polyethylene terephthalate sheet or the like, the transparency can be maintained, but the cost becomes high.
Moreover, you may give well-known easy-adhesion processes, such as a corona discharge process, an ozone spraying process, a plasma process, an easily-adhesive primer coating process, to a transparent base material as needed. For example, in the case of a polyethylene terephthalate sheet or the like, further easy adhesion treatment can be omitted if a commercially available easy adhesion treatment product is used.
[0023]
[Metal layer]
The metal layer 2 is a layer formed in a fine pattern, such as a lattice, in order to ensure apparent light transmittance and maintain electromagnetic wave shielding performance even in a layer made of a metal which is an opaque material. Such a metal layer 2 can be formed by patterning the conductive metal foil 2 by etching.
The material of the conductive metal foil is not particularly limited as long as it is conductive and can be etched, but copper, aluminum and the like are preferable in terms of availability. Among these, copper is most preferable because it is excellent in electrical conductivity and fine etching suitability but is expensive.
[0024]
The conductive metal foil preferably has a surface roughened (roughened) on the surface on the adhesive layer side in order to enhance adhesion to the transparent substrate. In addition, when the light-transmitting electromagnetic wave shielding sheet is obtained by the roughening treatment, it is possible to eliminate the metallic luster that normally causes glare and hinders the appearance.
In addition, the thickness of the conductive metal foil may be determined according to the use, the fineness of the pattern, etc., but is usually about 5 to 50 μm and a thin pattern (for example, a thin line of 50 μm or less, particularly 40 μm or less). Is preferably about 9 to 18 μm.
[0025]
[Adhesive layer]
Then, after the conductive metal foil is laminated and integrated with the transparent base material and the adhesive, the resist layer is formed in a pattern and etched to form a desired patterned metal layer. A typical method for laminating a transparent substrate and a conductive metal foil is a dry lamination method. In addition, since the adhesive layer 3 remains in the portion where the unnecessary portion of the conductive metal foil is removed, the adhesive layer is made transparent so as not to hinder the light transmittance.
[0026]
What is necessary is just to use suitably the adhesives used for the adhesive bond layer 3 according to a use, for example, curable adhesives, such as a urethane resin and an epoxy resin, are mentioned. Among them, urethane resin adhesives that use polyester polyol as the main agent and isocyanate curing agent as the curing agent are cost, coating suitability, transparency after curing, curability at relatively low temperatures, and handleability. It is one of the preferable adhesives in that it is excellent in. The adhesive may be applied by a coating method such as roll coating or spray coating, or a printing method such as gravure printing or screen printing.
[0027]
[Resist layer]
The resist layer 4 is a resist for forming the metal layer 2 in a pattern, and forms a conductive resist layer 4A that is made conductive by containing conductive particles in at least a portion to be a ground portion. The ground part is usually the end of the sheet. Therefore, the normal sheet non-conductive resist layer 4B may be used as the center portion of the sheet that is not used as the ground portion. The resist layer 4 is formed as an etching resist in a pattern on the conductive metal foil, and then the conductive metal foil is etched to form the patterned metal layer 2, and then left as it is. The resist layer 4 is in contact with and laminated thereon.
The conductive metal foil is etched by a known etching solution, for example, when the metal is copper, a general ferric chloride solution, a copper chloride solution, or the like.
[0028]
The method for forming the resist layer 4 in a pattern on the conductive metal foil is not particularly limited, but a photolithography method in which a photoresist is applied to the entire surface of the conductive metal foil, and then exposed and developed, or a conductive metal A typical printing method is to form a pattern on the foil from the beginning. In particular, in the case of building windows and the like, the printing method is superior to the photolithography method in terms of productivity and a large area.
[0029]
As a printing method in the printing method, offset printing, screen printing, gravure printing, flexographic printing, or the like may be used. Although a fine pattern can be formed by screen printing, it is difficult for a fine pattern having a line width of 50 μm or less, particularly 40 μm or less, and it is wide (1 m or more) and is continuously printed on a continuous strip. Not suitable for. In these respects, flexographic printing is preferable. Note that gravure printing is also possible if the pattern has a line width of 80 μm or more. Screen printing is possible even for fine lines of 20 μm, but it does not become an endless continuous pattern as a continuous strip. This is because a continuous pattern is preferable because it can be used for a window without waste. Also, fine lines are possible for offset printing, but this also does not form a continuous pattern as a continuous strip.
[0030]
The ink used as the etching resist is not particularly limited, and for example, ionizing radiation curable resin ink that is cured by ultraviolet rays or the like can be used. The ink is diluted with an organic solvent or water according to the printing method.
[0031]
The ionizing radiation curable resin used in the ionizing radiation curable resin ink is a resin in which various known monomers, oligomers, prepolymers, etc. are appropriately selected and blended in consideration of viscosity, adhesion, pigment dispersibility, etc. Compositions can be used. Moreover, when making a viscosity into a high viscosity, what is necessary is just to set it as the ink mixing | blending mainly by an oligomer and a prepolymer. Examples of such ionizing radiation curable resins include acrylate resins (compositions) such as epoxy acrylate and polyester acrylate.
The ionizing radiation is ultraviolet rays, electron beams, and the like. The ultraviolet curable resin ink is cured by ultraviolet irradiation, and the electron beam curable resin ink is cured by electron beam irradiation.
[0032]
Moreover, if a colored ink is used, a resist layer can be colored. The coloring color may be selected according to the application, but in order to make the pattern inconspicuous in appearance, a dark color such as black or amber is preferable. For example, in the case of black, a colored ink containing a carbon pigment or the like is used. When the metal layer is formed with a copper conductive metal foil with the adhesive layer side roughened by making the resist layer black, the appearance on the resist layer side is similar to the roughened surface. Can be.
[0033]
By using the ink as described above, the resist layer 4 can be formed as a normal (that is, a normal non-conductive resist layer 4B containing no conductive particles).
[0034]
And in order to make the resist layer 4 express electroconductivity and to set it as the electroconductive resist layer 4A, electroconductive particles are contained in the ink as described above. As the conductive particles, conductive carbon particles are preferable as the conductive particles that are less likely to be attacked by the etching solution than the metal of the metal layer. Further, the conductive carbon particles may be graphite particles or the like. The particle diameter of the conductive carbon particles is preferably 10 nm to 10 μm. The particle size is appropriately selected depending on the printing method or the like. As a guideline, it is 1 μm to 10 μm, more preferably 1 μm to 5 μm for screen printing where the printing thickness is easily obtained, and 10 nm to 1 μm for offset printing or flexographic printing capable of thin film printing. If the thickness of the resist layer to be formed is reduced, the conductive particles protrude from the surface of the layer, thereby obtaining more electrical continuity between the metal layer and the outside (via the conductive resist layer) such as a metal frame. It becomes easy.
[0035]
The conductive resist layer is more conductive when it has good conductivity, but the content of conductive particles increases, which adversely affects adhesion and curability. Therefore, considering these points, the conductivity is 10^-1-10⁹About Ω · cm, more preferably 10²-10⁷Ω · cm is good. In addition, even if the ink itself has almost no conductivity (that is, even when the conductive resist layer is formed thick, conductivity is hardly obtained), the particle size of the conductive particles is larger than the thickness of the conductive resist layer. If the conductive resist layer is formed to have a large thickness, the conductive particles form a bridge between the metal layer and the outside such as a metal frame to obtain conductivity. The conductive resist layer may be a resist layer having such conductivity.
For example, in flexographic printing, since a conductive resist layer can be obtained with a thin film having a thickness of about 1 μm, conduction can be obtained by adding a small amount of conductive particles. Further, in the case of a thin film, since the impedance is substantially lowered and becomes conductive with respect to a high frequency, it is considered that the conductivity of the ink may be low if it is a thin film.
[0036]
The carbon pigment as the colorant is also the same in that it is conductive carbon particles and carbon particles, but the so-called carbon pigment is a product manufactured for coloring purposes and not a product manufactured for conductive purposes. Even with the same content, almost no conductivity is obtained, which is different from the conductive carbon particles.
In addition, the conductive carbon particles are preferable in that the conductive resist layer can be colored black, so that the pattern becomes inconspicuous as described above, or a color similar to the roughened surface of the metal layer can be obtained.
[0037]
[Metal layer pattern shape]
The pattern shape in plan view of the metal layer (or resist layer) may be an arbitrary shape depending on the application. As a pattern that can ensure light transmission at least in the center of the sheet, a pattern that can easily be grounded may be used when light transmission is not required at the end of the sheet. The shape of the pattern can be easily dealt with by generating an image of an arbitrary shape by publicly known digital image processing on a computer at the time of printing a manuscript or a printing plate.
[0038]
For example, as a pattern for ensuring light transmittance together with electromagnetic wave shielding performance, the shape of the non-formed portion of the metal layer 2 (the portion that becomes an opening with respect to the metal layer) is a square [see, for example, FIG. , White portion in the drawing], rectangle (for example, see FIG. 4 (B)), triangle (for example, FIG. 4 (C)), hexagon (for example, see FIG. 4 (D)), octagon, other polygons, or these Polygonal shape with rounded corners (for example, see FIG. 4 (F)), circular shape (for example, see FIG. 4 (E)), elliptical shape, or a combination of these shapes (for example, octagonal and quadrangular) Etc. In addition, the arrangement of these shapes is not limited to the lattice arrangement of a square lattice (for example, see FIGS. 4A, 4E, and 4F), and the arrangement is adjusted to make a staggered pattern (for example, FIGS. C)] can also be used.
Needless to say, it is preferable in terms of electromagnetic wave shielding performance that the metal layer forming portion has a continuous shape without being divided.
[0039]
In order to form a metal layer with such a pattern, when printing a resist layer with this pattern, multicolor printing can be used for printing. As a result, the sheet central portion forms a non-conductive resist layer, while the sheet end portion can easily form a conductive resist layer. In this case, at least a portion is overprinted so that the pattern made of the non-conductive resist and the pattern made of the conductive resist are connected. At that time, the non-conductive resist layer may be printed on the entire edge of the sheet with a lattice pattern or the like, and the conductive resist layer may be overprinted only on the edge of the sheet including the upper part. In particular, in window applications, if the sheet center that does not need to be electrically connected to the window frame is made of a non-conductive resist layer, durability (for example, adhesion, weather resistance, heat resistance, water resistance, moisture resistance, etc.) can be obtained. This is preferable because it makes it easy to achieve important specifications.
[0040]
In order to achieve both high light transmission and electromagnetic wave shielding performance, the metal layer pattern is formed as thin as possible and the non-formed part is as wide as possible. For example, it is formed by a thin line having a line width of 50 μm or less. Note that light transmittance can be obtained even in a dot pattern (for example, FIGS. 4E and 4F). However, in this case, although the light transmittance is reduced, a high electromagnetic wave shielding performance of 60 to 70 dB or more can be obtained.
[0041]
On the other hand, as illustrated in FIG. 1B, the sheet end e may be grounded there, or may have a pattern in which an opening is provided in the same manner as the sheet center c. However, if the sheet end portion does not require light transmission, a pattern without an opening such as a belt-like pattern may be used as illustrated in FIG. For example, if the part is inserted into a metal frame of an aluminum frame at the same time as a window and grounded, it is not visible to the outside, so light transmission is unnecessary. Therefore, a pattern provided with an opening is not necessary for the sheet edge where light transmission is unnecessary, and the portion may be, for example, a belt-like full-surface pattern. Moreover, it is preferable to use a full-surface pattern at the grounding portion because the conductive area increases. Therefore, even when the conductive resist layer 4A is the entire sheet, the sheet end e may be formed as a belt-like pattern or the like as shown in FIG.
[0042]
[Other component layers]
The light-transmitting electromagnetic wave shielding sheet according to the present invention may be additionally provided with other constituent layers as necessary. For example, a surface protective layer, a hard coat layer, an adhesive layer, a heat ray cut layer, and the like.
[0043]
For example, the surface protective layer is provided on the metal layer forming surface side in order to protect the metal layer from surface oxidation or the like. The surface protective layer may be coated with a transparent resin. For the formation of the surface protective layer, a coating method such as spray coating, roll coating or gravure coating, or a printing method such as screen printing can be used. An acrylic resin, a polyester resin, a urethane resin, or the like can be used as the transparent resin, but a resin having adhesiveness to other layers that are in contact with the surface protective layer and film strength may be appropriately selected. Moreover, you may add well-known coupling agents, such as a silane coupling agent, in a coating liquid for adhesive improvement.
[0044]
It is also preferable that the surface protective layer is a hard coat layer. To make a hard coat layer, for example, a urethane resin, or a curable resin from which a hard coating film such as an ionizing radiation curable resin such as an acrylate type is obtained is used, and if necessary, silica, A hard inorganic powder such as alumina may be added. Moreover, you may provide such a hard coating film also with respect to the transparent base material side opposite to the metal layer side. The hard coat layer can also provide cleaning suitability (surface hardness) at the time of enforcement and cleaning (such as a window).
[0045]
An adhesive layer may be provided, and the light-transmitting electromagnetic wave shielding sheet can be easily attached to a window or the like with the adhesive layer. What is necessary is just to provide an adhesive layer as a transparent layer in the surface at the side of a metal layer or a transparent base material. As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, a known pressure-sensitive adhesive such as an acrylic resin, rubber, or silicone may be appropriately used depending on the application. In order to protect the pressure-sensitive adhesive layer until enforcement, it is preferable to further laminate a release paper on the pressure-sensitive adhesive layer. As the release paper, a known paper base, a resin base, a composite base of paper and resin, or the like may be used as appropriate.
[0046]
In addition, the heat ray cut layer is a heat ray cut in which a known infrared absorber is added to the resin of the surface protective layer or the pressure-sensitive adhesive layer, and these layers are also used, or an infrared absorber is added to the transparent resin. What is necessary is just to laminate a sheet. In addition, a heat ray cut sheet is good also as a structural layer of a transparent base material. In addition, as resin of a transparent resin sheet, resin etc. which were mentioned by the above-mentioned transparent base material are used.
[0047]
[Construction]
In addition, when constructing a glass plate applied by attaching a light-transmitting electromagnetic wave shielding sheet or the like on a window or the like, it is preferable that the glass plate is fitted into a metal frame such as an aluminum frame made of aluminum in order to easily conduct electricity. In that case, it is preferable to wash | clean, polish, etc. of a contact surface in the part which contact | connects the conductive resist layer surface of a light transmissive electromagnetic wave shielding sheet so that it may become easy to obtain conduction | electrical_connection.
[0048]
【Example】
The following examples further illustrate the present invention.
[0049]
[Example 1]
A light transmissive electromagnetic wave shielding sheet 10 as shown in the sectional view of FIG. 1A and the plan view of FIG. 1B was produced as follows.
First, a laminated sheet was prepared by laminating a 12 μm thick copper foil as a conductive metal foil to a 100 μm thick polyethylene terephthalate sheet as the transparent substrate 1 using a urethane adhesive for dry lamination. Next, a solvent-free black UV curable resin ink made conductive by adding conductive carbon particles (average particle size 2 μm) by flexographic printing on the conductive metal foil surface of the laminated sheet, in a desired pattern shape The ink was cured by printing to a thickness of 1 μm to form a conductive resist layer 4 </ b> A as the resist layer 4. Note that the pattern has a lattice pattern as shown in FIG. 4A, the opening is square, the line width is 30 μm, and the opening width is 250 μm.
[0050]
Next, etching is performed using a ferric chloride solution, and unnecessary conductive metal foil is removed from the non-printed portion while leaving the resist-printed portion to form a patterned metal layer 2, and the resist on the metal layer 2 is also formed. Was left without being removed to obtain a desired light-transmitting electromagnetic wave shielding sheet 10. The light transmittance was 70%. The light-transmitting electromagnetic wave shielding sheet 10 has a configuration in which the adhesive layer 3 is laminated on the entire surface of the transparent substrate 1, and the patterned metal layer 2 and conductive resist layer 4A are laminated thereon. is there.
[0051]
Next, as shown in the cross-sectional view of FIG. 3, the light transmissive electromagnetic wave shielding sheet 10 is attached to an aluminum metal frame 30 together with the glass plate 20 to obtain a light transmissive electromagnetic wave shielding body 40. At that time, the light-transmitting electromagnetic wave shielding sheet 10 has the metal layer side facing the metal frame 30 so that the conductive resist layer is in contact with the inner surface of the metal frame. The portion of the inner surface of the metal frame that contacts the resist layer was lightly polished with a paper file to facilitate conduction.
[0052]
As for the electromagnetic wave shielding performance of the obtained light transmissive electromagnetic wave shielding body 40, no deterioration in performance due to the frame attachment was observed, and the ground to the frame was good, and it was 44 dB at 1 GHz. When the surface resistance of the resist printing surface is measured, 3.5 × 10^-2It was considered that the conductive particles having a particle diameter larger than the thickness of the conductive resist layer 4A formed a bridge and were electrically connected to the metal layer 2.
[0053]
[Example 2]
A light transmissive electromagnetic wave shielding sheet 10 as shown in the sectional view of FIG. 1C and the plan view of FIG.
In Example 1, the resist printing was changed to the following two-color printing. That is, the first color of resist printing is the same as in the case of the conductive resist layer of Example 1 using non-conductive ink (solvent-free black ultraviolet curable resin ink without conductive carbon particles). A non-conductive resist layer 4B was formed over the entire sheet with a lattice pattern of the print pattern (see FIG. 2A). For the second color, the conductive ink used in Example 1 is used, the sheet center portion c is left, and only the first end 1 (at both ends in the width direction of the continuous belt-like sheet: both left and right sides in the drawing). The conductive resist layer 4A was formed in a 1 cm wide strip shape so as to overlap the sheet edge portion of the non-conductive resist layer 4B due to color [see FIG. 2B].
[0054]
Then, etching was conducted in the same manner as in Example 1 to produce a light transmissive electromagnetic wave shielding sheet 10, and a light transmissive electromagnetic wave shielding body 40 was further produced in the same manner as in Example 1.
The light-transmitting electromagnetic wave shielding sheet 10 has an adhesive layer 3 laminated on the entire surface of the transparent substrate 1, a patterned metal layer 2 laminated thereon, and a non-conductive resist on the metal layer. The layer 4B is laminated, and the sheet end portion e is further laminated with the conductive resist layer 4A. Since the sectional view of FIG. 1C is a conceptual drawing, the sheet end e is simply drawn in a layer configuration in which the conductive resist layer 4A is directly laminated on the metal layer 2, Specifically, in the case of the present embodiment, the lattice-patterned thin line portion has a layer structure in which the conductive resist layer 4A is laminated on the metal layer 2 via the nonconductive resist layer 4B.
[0055]
The light transmittance at the center of the obtained light transmissive electromagnetic wave shielding sheet was 70%. Further, the electromagnetic wave shielding performance of the light transmissive electromagnetic wave shielding body was found to be 50 dB at 1 GHz with no deterioration in performance due to frame attachment and good grounding to the frame.
[0056]
Example 3
In Example 1, the resist printing pattern was the same as in Example 1 except that the opening was changed from a square to a circular hole as shown in FIG. 4E, and the hole diameter was 80 μm and the hole pitch was 160 μm. Thus, a light transmissive electromagnetic wave shielding sheet and a light transmissive electromagnetic wave shielding body were produced.
As a result, the electromagnetic wave shielding performance of the light-transmitting electromagnetic wave shielding body was found to be 70 dB at 1 GHz with no deterioration in performance due to frame attachment and good grounding to the frame.
[0057]
【The invention's effect】
(1) According to the light transmissive electromagnetic wave shielding sheet of the present invention, the ground can be easily taken from the surface of the light transmissive electromagnetic wave shielding sheet. Therefore, for example, a conductive treatment with a window frame such as an aluminum sash is facilitated when the window is constructed.
(2) At that time, if the conductive resist layer is formed on the entire surface including the sheet center portion and the sheet edge portion, the conductive resist layer is formed by applying a conductive resist to the resist when the metal layer is patterned by etching. Since it is only necessary to leave it after use and etching, it becomes a light-transmitting electromagnetic wave shielding sheet that is simple in production.
(3) Alternatively, if the conductive resist layer is formed only at the sheet end portion and the sheet central portion is formed with a non-conductive resist layer, the resist layer in the center portion of the sheet needs to consider conductivity. Therefore, a normal resist can be used, and specifications that emphasize various durability required for application to architectural windows and the like such as adhesion, weather resistance, heat resistance, water resistance, and moisture resistance become easy.
(4) If conductive carbon particles are used as the conductive particles of the conductive resist layer, the conductive resist layer can be made black, and even if the conductive resist layer is provided at the center of the sheet, the pattern is conspicuous in appearance. It can be difficult.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view and a plan view conceptually showing the light-transmitting electromagnetic wave shielding sheet of the present invention in its two forms.
FIG. 2 is a plan view conceptually illustrating how a resist layer is printed in two colors with a non-conductive resist layer and a conductive resist layer.
FIG. 3 is a cross-sectional view showing an example in which a light-transmitting electromagnetic wave shielding sheet is attached to a metal frame together with a glass plate.
FIG. 4 is a plan view illustrating some of the patterns of the metal layer.
[Explanation of symbols]
1 Transparent substrate
2 Metal layers
3 Adhesive layer
4 resist layer
4A conductive resist layer
4B Non-conductive resist layer
10 Light transmissive electromagnetic wave shielding sheet
20 Glass plate
30 metal frame
40 Light transmissive electromagnetic wave shield
c Seat center
e Seat edge

Claims (4)

In the light-transmitting electromagnetic wave shielding sheet, a patterned metal layer is laminated on a transparent substrate via an adhesive layer, and a resist layer is further laminated on the pattern of the metal layer,
The resist layer is composed of a conductive resist layer containing conductive particles, and the conductive resist layer is formed in contact with the metal layer ,
The particle size of the conductive particles is larger than the thickness of the conductive resist layer ,
Light transmissive electromagnetic wave shielding sheet.   The light-transmitting electromagnetic wave shielding sheet according to claim 1, wherein the conductive resist layer is formed on the entire surface including the sheet center portion and the sheet end portion.   The light-transmitting electromagnetic wave shielding sheet according to claim 1, wherein the conductive resist layer is formed only at the end of the sheet, and the resist layer at the center of the sheet is formed with a non-conductive resist layer.   The light transmissive electromagnetic wave shielding sheet according to claim 1, wherein the conductive resist layer contains conductive carbon particles as conductive particles.

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