JP2008159771A - Electromagnetic wave shielding material of frequency selective transmission type and its production process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve transparency and productivity of an electromagnetic wave shielding material of frequency selective transmission type. <P>SOLUTION: The electromagnetic wave shielding material 1 of frequency selective transmission type is provided, at least on one side of a transparent base 2, with FSS elements 3 of thin line patterns so as to shield electromagnetic waves of a predetermined frequency, wherein a metallization layer of the FSS elements 3 is composed by forming a developed silver layer on the transparent base 2 by a photography process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a frequency selective shielding type electromagnetic shielding material that selectively shields only electromagnetic waves of a predetermined frequency and transmits electromagnetic waves of other frequencies, and a manufacturing method thereof.

  In recent years, electromagnetic waves generated from various electronic devices have a negative effect on the human body and malfunction of surrounding electronic devices has become a problem. Furthermore, with the spread of wireless LAN, communication data in buildings has been It has become necessary to prevent leakage and interception outside the network, and countermeasures against frequency selective shielding type electromagnetic shielding that selectively transmits or shields only electromagnetic waves of a predetermined frequency are becoming increasingly important is there.

  Conventionally, as a frequency selective shielding type electromagnetic shielding material that selectively shields only electromagnetic waves of a predetermined frequency and transmits electromagnetic waves of other frequencies, an FSS element (FSS: Frequency Selective Surface) made of a conductor is repeatedly arranged. Is known (see Patent Documents 1 to 7).

(1) An etching method in which a metal foil is bonded to a transparent substrate or a metal thin film is deposited on the transparent substrate, and then a pattern of an FSS element is formed by a photolithographic method (Patent Documents 1 to 3).
(2) A printing method in which a metal paste is printed on a transparent substrate to form an FSS element pattern (Patent Documents 4 to 6).
(3) A method of forming a pattern of an FSS element with a metal wire or a metal piece on a transparent substrate (Patent Document 7).

In addition, as a method for producing an electromagnetic wave shielding material using a conductive layer provided on a base material, there is a method shown in the following (4).
(4) Photographic silver-plating method in which metallic silver is developed by a photographic method to form a fine line pattern, and then a conductive layer is formed by plating on the metallic silver (for example, Patent Documents 8 and 9)

  There are two methods shown in the following (a) and (b) for forming a fine pattern of metallic silver by a photographic method.

(A) A silver salt-containing layer containing a silver salt provided on a support is exposed and developed to form a metallic silver part and a light-transmitting part, and the metallic silver part is further subjected to physical development and A method of forming a conductive metal part in which conductive metal particles are supported on the metal silver part by plating treatment (for example, see Patent Document 8). In this method, developed silver does not appear in the portion that is covered with the exposure mask and is not exposed, and developed silver appears in the portion that is not covered with the exposure mask and exposed. Therefore, compared with the exposure mask. This is a negative exposure / development method in which developed silver appears in an inverted form.

(B) A light-sensitive material having a physical development nucleus layer and a silver halide emulsion layer in this order is exposed on a transparent substrate, and metallic silver is deposited on the physical development nucleus in an arbitrary fine line pattern. A method of plating a metal using the physically developed metallic silver as a catalyst nucleus after removing a layer provided on the development nucleus (see, for example, Patent Document 9). In this method, developed silver appears in a portion which is covered with the exposure mask and is not exposed, and developed silver does not appear in a portion which is not covered with the exposure mask and exposed. Is a positive exposure / development method (silver complex diffusion transfer method, hereinafter referred to as DTR method).
US Pat. No. 4,656,487 Japanese Patent Laid-Open No. 11-195890 JP 2003-258487 A Japanese Patent Laid-Open No. 10-1206090 JP 2000-68675 A Japanese Patent Laid-Open No. 11-68374 JP-A-8-330783 JP 2004-221564 A International Publication No. 2004/007810 Pamphlet

In the case of using the etching method described in (1) above, from the viewpoint of saving resources, only a very small portion that becomes a thin line portion is left by etching, and most other metals are dissolved and removed. It is a problem. In addition, there is a problem that the cost of processing the waste liquid used in the etching process increases.
In addition, since the maximum standard dimension width of a commercially available metal foil is approximately 600 mm or less, a frequency selective shielding type electromagnetic shielding material having a wider dimension width cannot be produced by the method of laminating the metal foil. Further, when the conductive layer is formed by vapor deposition, there is a problem in that it cannot be easily manufactured because a huge equipment cost is required.

When the printing method described in the above (2) is used, for example, in paragraph 0038 of Patent Document 6, “The line width of the FSS element 3 can be printed with a silver paste or the like to a width of about 0.1 mm to 1.2 mm. However, in consideration of safety against disconnection due to heat or the like, it is preferably 0.3 mm or more, and in this embodiment, the line width is 0.4 mm. ” There was a problem that it was difficult to make the width 30 μm or less, and it was difficult to ensure transparency (not visually observed). In addition, there is a problem that the adhesiveness between the transparent substrate and the conductive layer is poor and is easily peeled off.
When the method (3) is used, it is difficult to work with a metal wire with a reduced thickness or a metal piece with a reduced width, and the thickness is 60 μm or less so that it cannot be visually recognized by human eyes. It was difficult to form a pattern of FSS elements and arrange them on a substrate.

  Thus, conventionally, a frequency selective shielding type electromagnetic wave shielding material suitable for being attached to a window glass or the like of a large building and a manufacturing method thereof have not been known.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the electromagnetic wave shielding material of the frequency selective shielding type excellent in transparency (not visually observed) and productivity, and its manufacturing method.

In order to solve the above problems, the present invention is a frequency selective shielding type electromagnetic shielding material in which an FSS element made of a fine line pattern for shielding electromagnetic waves of a predetermined frequency is disposed on at least one surface of a transparent substrate. According to another aspect of the present invention, there is provided a frequency selective shielding type electromagnetic wave shielding material, wherein the metal layer of the FSS element comprises a developed silver layer produced by a photographic method.
The metal layer preferably has a line width of 15 to 60 μm.
The developed silver layer is preferably a developed silver layer produced by a positive photographic process or a developed silver layer produced by a negative photographic process.

  Further, the present invention is a method for producing a frequency selective shielding type electromagnetic shielding material in which an FSS element comprising a thin line pattern for shielding electromagnetic waves of a predetermined frequency is disposed on at least one surface of a transparent substrate, A substrate having a layer containing a material that deposits metallic silver by exposure and development is exposed to at least one surface of the transparent substrate, and then developed, whereby the pattern of the FSS element is generated by the developed silver layer. The method of manufacturing the electromagnetic wave shielding material of the frequency selective shielding type characterized by including the process to perform at least.

  Further, the present invention is a method for producing a frequency selective shielding type electromagnetic shielding material in which an FSS element comprising a thin line pattern for shielding electromagnetic waves of a predetermined frequency is disposed on at least one surface of a transparent substrate, By exposing a base material provided with a layer containing a substance capable of depositing metallic silver by exposure and development to at least one surface of a long transparent base material using a continuous exposure apparatus, and then developing, There is provided a method for producing a frequency selective shielding type electromagnetic wave shielding material, comprising at least a step of generating a pattern of an FSS element by a developed silver layer.

The continuous exposure apparatus includes a cylindrical drum made of a material that transmits light used for exposure, an exposure mask portion provided on an outer peripheral wall of the cylindrical drum, and an exposure light source disposed in the cylindrical drum. The apparatus which irradiates light from the inside of a cylindrical drum with respect to the transparent base material wound around the said cylindrical drum can be used.
Alternatively, as a continuous exposure apparatus, a cylindrical drum, an exposure mask film on which a continuous pattern is formed, and an exposure light source disposed outside the cylindrical drum, and transparently wound around the cylindrical drum. An apparatus for irradiating light to the base material and the exposure mask film from the outside of the cylindrical drum can also be used.

  In the method for producing a frequency selective shielding type electromagnetic shielding material of the present invention, the developed silver layer is preferably produced by a positive photographic method or a negative photographic method.

  According to the electromagnetic wave shielding material of the frequency selective shielding type of the present invention, since the FSS element composed of a fine line pattern for blocking electromagnetic waves of a predetermined frequency is formed by the developed silver layer generated by the photographic method, the metal layer The line width can be made sufficiently narrow, and the transparency (not visible) and the productivity are excellent.

  According to the method of manufacturing the electromagnetic wave shielding material of the frequency selective shielding type of the present invention, the FSS element composed of a fine line pattern for blocking electromagnetic waves of a predetermined frequency is formed by the developed silver layer generated by the photographic method. The line width of the metal layer can be made sufficiently narrow, and the FSS element can be formed with high accuracy by generating a developed silver layer, which is excellent in transparency (not visible) and productivity.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a drawing showing an example of a frequency selective shielding electromagnetic shielding material of the present invention, and FIG. 1 is a front view showing a schematic configuration of the frequency selective shielding electromagnetic shielding material. 2A to 2K are partially enlarged front views showing examples of patterns of FSS elements, respectively.
FIG. 3 is a schematic view showing an example of a continuous exposure apparatus. FIG. 4 is a schematic view showing another example of the continuous exposure apparatus.

The frequency selective shielding type electromagnetic shielding material 1 shown in FIG. 1 has a large number of FSS elements 3 each having a thin line pattern for shielding electromagnetic waves of a predetermined frequency on one side of a long transparent base material 2. The metal layer constituting the FSS element 3 is a developed silver layer produced by a photographic method.
If necessary, an adhesive layer and a release film (both not shown) for protecting the pressure-sensitive adhesive layer can be provided on the other surface (back surface) of the transparent substrate 2. The frequency selective shielding type electromagnetic shielding material provided with the pressure-sensitive adhesive layer can be easily attached to the surface of glass or the like by peeling off the release film.

(Transparent substrate)
The transparent substrate 2 used in the present invention preferably has transparency in the visible region and generally has a total light transmittance of 90% or more. Especially, the resin film which has flexibility is preferable as the transparent base material 2 since it is excellent in handleability. Specific examples of the resin film used for the transparent substrate 2 include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic resins, epoxy resins, fluororesins, silicone resins, polycarbonate resins, and diacetates. A single-layer film having a thickness of 50 to 300 μm made of resin, triacetate resin, polyarylate resin, polyvinyl chloride, polysulfone resin, polyether sulfone resin, polyimide resin, polyamide resin, polyolefin resin, cyclic polyolefin resin, or the like. And a multi-layer composite film.

(FSS element)
On the transparent substrate 2, FSS elements 3 for shielding electromagnetic waves of a predetermined frequency are regularly arranged at regular intervals. In general, an FSS element is an element that resonates with an electromagnetic wave having a predetermined frequency and shields the frequency. In the case of the electromagnetic wave shielding material of the frequency selective shielding type of the present invention, an FSS element composed of a thin line pattern is used from the viewpoint of the permeability of the electromagnetic wave shielding material of the frequency selective shielding type. The optimum specifications of the shape, size, arrangement, etc. of the FSS element composed of the fine line pattern are designed according to the frequency to be shielded.

  The method for producing the FSS element 3 in the electromagnetic wave shielding material of the frequency selective shielding type of the present invention will be described in detail later, but it is carried out by a method of producing a developed silver layer with the same pattern as the target FSS element 3 by a photographic method. By using this method, it becomes easy to form the FSS element 3 having a thin line pattern, and it is possible to manufacture the frequency selective shielding type electromagnetic shielding material 1 including the FSS element having both excellent permeability and electromagnetic shielding effect. it can.

  In the electromagnetic wave shielding material 1 of the frequency selective shielding type of the present invention, the FSS element 3 is constituted by a fine line pattern made of a metal layer in order to ensure transparency (not visually observed). The line width of the metal layer constituting the FSS element 3 is preferably 15 to 60 μm, and more preferably 15 to 30 μm.

  A preferable shape of the FSS element 3 is an open figure formed by a combination of line segments having ends as shown in FIGS. 2B and 2C, and ends as shown in FIGS. 2F and 2G. A closed figure (annular figure), etc. that do not have, and in addition, a combination of an open figure and a closed figure as shown in FIG. 2 (d), and two kinds of closed large and small as shown in FIG. 2 (h) There are combinations of figures. The dimension of the FSS element 3 is about ¼ of the wavelength of the electromagnetic wave to be shielded by the length from the center of the line segment in the case of an open figure composed of a combination of line segments having ends. Further, in the case of a closed figure (annular figure) that does not have an end, the length of the periphery is set to be the same as the wavelength of the electromagnetic wave to be shielded.

The FSS element shown in FIG. 2A is a set of four squares (square loop type) whose outlines are formed by thin lines of metal layers.
The FSS element shown in FIG. 2 (b) has an inverted Y-shape (tripol type) formed of thin metal layers. According to the element of this shape, each of the three sides functions as a dipole antenna, and an electromagnetic wave shield can be provided against any inclination of radio waves.
The FSS element shown in FIG. 2 (c) has a cross shape (cross dipole type) formed of thin metal layers. Thereby, an electromagnetic wave shield can be provided in both the horizontal direction and the vertical direction.
The FSS element shown in FIG. 2 (d) is formed by forming a triangular outline and a Y-shape inside the triangle by fine lines of a metal layer. The triangular element and the inverted Y-shaped element respectively emit electromagnetic waves having different wavelengths. Can be shielded.

The FSS element shown in FIG. 2 (e) has a double square outline formed by thin metal layer lines.
The FSS element shown in FIG. 2 (f) has an inverted Y-shaped outline formed in an annular shape by a thin wire of a metal layer.
In the FSS element shown in FIG. 2G, a cross-shaped contour is formed in an annular shape by a thin line of a metal layer.
The FSS element shown in FIG. 2 (h) is formed by forming a cross-shaped outline and an X-shaped outline in an annular shape by a thin line of a metal layer.

The FSS element shown in FIG. 2 (i) is formed by forming an H-shaped outline by a thin wire of a metal layer and alternately arranging a vertical H-shape and a horizontal H-shape.
The FSS element shown in FIG. 2 (j) has a triangular outline formed by fine lines of a metal layer. In the horizontal direction, triangles in the normal position and triangles in the reverse position are alternately arranged, and in the vertical direction. Are the same in the forward and reverse positions, arranged in rows. Thereby, the installation density of a FSS element can be made high and the electromagnetic wave shielding effect can be improved.
In the FSS element shown in FIG. 2 (k), a V-shaped contour is formed by a thin line of a metal layer, and a V-shape at a normal position and a V-shape at a reverse position are alternately arranged.

  In addition, although illustration is omitted, a circular ring type, a Jerusalem cross type, or a fractal shape that is self-similar to a desired basic shape may be exemplified as FSS element shapes that can be applied to the present invention. it can. Moreover, it is also possible to constitute an electromagnetic wave shielding material capable of selecting and shielding electromagnetic waves having two or more types of frequencies by using a combination of two or more different types of FSS elements having different shapes and dimensions.

  In the case of an application covering a relatively small area, as shown in FIG. 1, a predetermined length direction of the transparent substrate 2 is provided so that the frequency selective shielding type electromagnetic shielding material can be easily cut for each fixed length. The arrangement of the FSS elements 3 may be divided for each length. In this case, in order to divide the frequency selective shielding type electromagnetic shielding material into the length 5, it is only necessary to cut at the cut portion 6 where the FSS element 3 is not provided. Thereby, it becomes easy to cut the transparent substrate 2 without cutting the FSS element 3.

  In the case of an application covering a large area, the FSS element 3 of the electromagnetic wave shielding material 1 of the frequency selective shielding type 1 is continuously provided without a break 6. Thereby, there is no leakage of the electromagnetic wave from the cut | interruption 6, and the electromagnetic wave shielding effect can be acquired over the whole length direction of the electromagnetic wave shielding material 1 of the frequency selective shielding type.

(Generation of developed silver layer)
In the exposure development method based on the photographic method for producing the developed silver layer, as described above, (a) developed silver appears in the exposed portion that is not covered with the exposure mask, that is, opposite to the exposure mask. The so-called negative exposure and development method in which developed silver appears in the form of (2), and (b) developed silver appears in the portion that is covered with the exposure mask and not exposed, that is, the developed silver appears in the same form as the exposure mask. There are two types of so-called positive exposure and development methods. Either (a) a negative exposure / development method or (b) a positive exposure / development method can be applied to the present invention.

  Hereinafter, a method for producing an FSS element pattern using a positive exposure / development method (DTR method) will be described. In the case of the DTR method, it is preferable that a physical development nucleus layer is provided in advance on the surface of the transparent substrate 2. As the physical development nuclei, fine particles (having a particle size of about 1 to several tens of nm) made of heavy metals or sulfides thereof are used. Examples thereof include colloids such as gold and silver, metal sulfides obtained by mixing water-soluble salts such as palladium and zinc and sulfides, and the like. These fine particle layers of physical development nuclei can be provided on the transparent substrate 2 by vacuum deposition, cathode sputtering, coating, or the like. From the viewpoint of production efficiency, a coating method is preferably used. The content of physical development nuclei in the physical development nuclei layer is suitably about 0.1 to 10 mg per square meter in solid content.

  The transparent substrate 2 can be provided with an adhesive layer of a polymer latex layer such as vinylidene chloride or polyurethane, and an intermediate layer made of a hydrophilic binder such as gelatin is provided between the adhesive layer and the physical development nucleus layer. You can also

  The physical development nucleus layer preferably contains a hydrophilic binder. The amount of the hydrophilic binder is preferably about 10 to 300% by mass with respect to the physical development nucleus. As the hydrophilic binder, gelatin, gum arabic, cellulose, albumin, casein, sodium alginate, various starches, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, a copolymer of acrylamide and vinyl imidazole, and the like can be used. The physical development nucleus layer may also contain a hydrophilic binder crosslinking agent.

  The physical development nucleus layer and the intermediate layer can be applied by an application method such as dip coating, slide coating, curtain coating, bar coating, air knife coating, roll coating, gravure coating, spray coating, and the like. In the present invention, the physical development nucleus layer is preferably provided as a continuous and uniform layer by the above-described coating method.

  The supply of silver halide for precipitating metallic silver on the physical development nucleus layer is performed by a method in which the physical development nucleus layer and the silver halide emulsion layer are integrally provided in this order on the substrate, or another paper or plastic resin film. There is a method of supplying a soluble silver complex salt from a silver halide emulsion layer provided on a substrate such as the above. From the viewpoint of cost and production efficiency, it is preferable to provide the former physical development nucleus layer and silver halide emulsion layer integrally.

The silver halide emulsion can be produced according to a general method for producing a silver halide emulsion of a silver halide photographic light-sensitive material. The silver halide emulsion is usually prepared by mixing and ripening an aqueous silver nitrate solution, an aqueous halogen solution of sodium chloride or sodium bromide in the presence of gelatin.
The silver halide composition of the silver halide emulsion layer preferably contains 80 mol% or more of silver chloride, and more preferably 90 mol% or more is silver chloride. The conductivity of the physically developed silver formed by increasing the silver chloride content is improved.

  The silver halide emulsion layer is sensitive to various light sources. In the present invention, when the pattern of the FSS element is formed by physically developed silver, as a method for exposing the silver halide emulsion layer, a method of exposing the FSS element pattern transmission original and the silver halide emulsion layer in close contact, or various lasers There is a method of scanning exposure using light. The former contact exposure is possible even if the silver halide has relatively low photosensitivity, but in the case of scanning exposure using laser light, relatively high photosensitivity is required. Therefore, when the latter exposure method is used, the silver halide may be subjected to chemical sensitization or spectral sensitization with a sensitizing dye in order to increase the sensitivity of the silver halide. Chemical sensitization includes metal sensitization using a gold compound or silver compound, sulfur sensitization using a sulfur compound, or a combination thereof. Gold-sulfur sensitization using a gold compound and a sulfur compound in combination is preferable. In the above-described method of exposing with laser light, a laser beam having an oscillation wavelength of 450 nm or less, for example, a blue semiconductor laser (also referred to as a violet laser diode) having an oscillation wavelength of 400 to 430 nm is used. It can be handled even under a yellow fluorescent lamp.

  Any position on the substrate on which the physical development nucleus layer is provided, for example, an adhesive layer, an intermediate layer, a physical development nucleus layer or a silver halide emulsion layer, a protective layer, or a backing layer provided with a support interposed therebetween. A dye or pigment for preventing irradiation may be contained.

  When developing silver using a photosensitive material in which a silver halide emulsion layer is applied directly on the physical development nucleus layer or via an intermediate layer, the transparent original of the FSS element pattern and the photosensitive material are adhered to each other. After exposure or scanning exposure of the above-mentioned photosensitive material to a digital image of an FSS element pattern with various laser light output machines, the silver is processed in an alkaline solution in the presence of a soluble silver complex salt forming agent and a reducing agent. Complex salt diffusion transfer development (DTR development) occurs, the silver halide in the unexposed area is dissolved to form a silver complex salt, which is reduced on the physical development nuclei to deposit metal silver to obtain a physically developed silver thin film having an FSS element pattern. be able to. The exposed portion is chemically developed in the silver halide emulsion layer to become blackened silver. After development, the silver halide emulsion layer and the intermediate layer, or the protective layer provided as necessary, are washed away with water, and the physically developed silver thin film of the FSS element pattern is exposed on the surface.

  After DTR development, the silver halide emulsion layer or the like provided on the physical development nucleus layer may be removed by washing with water or transferring and peeling to a release paper or the like. There are two methods for removing the water washing: a method of removing hot water using a scrubbing roller or the like while jetting it with a nozzle or the like, and a method of removing hot water by jetting with a nozzle or the like.

  On the other hand, when supplying a soluble silver complex salt from a silver halide emulsion layer provided on a substrate different from the substrate on which the physical development nucleus layer was coated, the silver halide emulsion layer was exposed in the same manner as described above. After that, the substrate coated with the physical development nucleus layer and another photosensitive material coated with the silver halide emulsion layer are superposed and adhered in an alkaline solution in the presence of a soluble silver complex salt forming agent and a reducing agent. Then, after taking out from the alkaline solution, after several tens of seconds to several minutes have passed, the both are removed to obtain a physically developed silver thin film having an FSS element pattern deposited on the physical development nuclei.

  Next, a soluble silver complex salt forming agent, a reducing agent, and an alkali solution necessary for silver complex diffusion transfer development will be described. The soluble silver complex salt forming agent is a compound that dissolves silver halide to form a soluble silver complex salt, and the reducing agent is a compound that reduces this soluble silver complex salt to precipitate metallic silver on physical development nuclei. These actions are performed in an alkaline solution.

  Examples of the soluble silver complex forming agent used in the present invention include sodium thiosulfate, thiosulfate such as ammonium thiosulfate, thiocyanate such as sodium thiocyanate and ammonium thiocyanate, alkanolamine, sodium sulfite, and potassium bisulfite. Sulfites such as T. H. Examples include the compounds described in 474-475 (1977) of James The Theory of the Photographic Process 4th edition.

  As the reducing agent, a developing agent known in the field of photographic development can be used. For example, polyhydroxybenzenes such as hydroquinone, catechol, pyrogallol, methylhydroquinone, chlorohydroquinone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-3-pyrazolidone, 1-phenyl-4-methyl- Examples include 3-pyrazolidones such as 4-hydroxymethyl-3-pyrazolidone, paramethylaminophenol, paraaminophenol, parahydroxyphenylglycine, paraphenylenediamine, and the like.

  The above-described soluble silver complex salt forming agent and reducing agent may be applied to the substrate together with the physical development nucleus layer, added to the silver halide emulsion layer, or contained in an alkaline solution. Further, it may be contained in a plurality of positions, but it is preferably contained in at least the alkaline liquid.

  The content of the soluble silver complex salt forming agent in the alkaline solution is suitably used in the range of 0.1 to 5 mol per liter of the developer, and the reducing agent is 0.05 to 1 per liter of the developer. It is suitable to use in the molar range.

  The pH of the alkaline solution is preferably 10 or more, and more preferably in the range of 11-14. Application of the alkaline solution for silver complex diffusion transfer development may be an immersion method or a coating method. The immersion method is, for example, a method in which a substrate provided with a physical development nucleus layer and a silver halide emulsion layer is transported while being immersed in an alkaline liquid stored in a large amount in a tank. About 40 to 120 ml of alkali solution per square meter is applied on the silver halide emulsion layer.

In order to ensure transparency (not visually observed), the FSS element 3 is constituted by a fine line pattern made of a metal layer. The line width of the metal layer constituting the FSS element 3 is preferably 15 to 60 μm, and more preferably 15 to 30 μm.
As described above, in the frequency selective shielding type electromagnetic shielding material of the present invention, when the line width of the fine line pattern constituting the FSS element is reduced to 60 μm or less, the transparency (not visually observed) increases, but the conductivity ( In addition, when the line width is increased to 60 μm or more, the transparency decreases and the conductivity increases.
The developed silver layer by physical development of an arbitrary fine line pattern formed on the transparent substrate according to the present invention has very small metal silver particles forming the developed silver layer obtained after the development treatment, and the developed silver layer Since the amount of the hydrophilic binder present in is extremely small, the developed silver layer is formed in a state in which the metallic silver particles forming the developed silver layer are close to the closest packed state, and thus has electrical conductivity.
According to the present invention, since the metal layer composed of the developed silver layer has high conductivity, the frequency selective shielding type electromagnetic shielding effect is not reduced even if the line width pattern of the thin line is thinned. The transparency of the electromagnetic shielding material can be increased.

(Manufacturing method for continuous production)
As described above, in order to manufacture a frequency selective shielding type electromagnetic shielding material covering a large area, the FSS element 3 is continuously generated on a long base (particularly, a long base extended from a roll). In such a case, it is preferable to feed a long base material from the raw roll and perform the exposure / development process of the developed silver layer by a roll-to-roll because there is an advantage that productivity can be improved.

  In such a manufacturing method, the raw roll is obtained by winding a sheet having a layer (in detail above) containing a substance that deposits metallic silver by exposure and development on a long substrate. It is. The base material drawn out from the original fabric roll is transferred by a transfer roll arranged at a required location. The substrate is first transferred to a continuous exposure apparatus and baked (exposed) with a predetermined mask pattern. Here, the continuous exposure apparatus is an apparatus that performs exposure while transferring the transparent base material by continuous feeding, as will be described in detail later. Next, the exposed base material is transferred to a developing device, and the developed silver that has been photographic developed is fixed to the pattern shape of the FSS element. Next, after passing through a water washing tank and washing, unnecessary foreign matters and contaminants are removed, drained and dried by a drier, and taken up on a roll again.

(Exposure equipment)
As an exposure apparatus using the above exposure method, there are a single wafer processing type exposure apparatus using a single wafer type exposure mask (photomask) and a continuous exposure apparatus capable of forming a continuous pattern. A single wafer processing type exposure apparatus uses a single wafer type exposure mask (photomask) on which a predetermined mask pattern is formed, feeds the substrate to the exposure apparatus intermittently, and evacuates the inside of the apparatus for exposure. After the mask and the substrate are brought into close contact with each other and no gap is formed, exposure is performed with, for example, ultraviolet rays. In a single wafer processing type exposure apparatus, since vacuum evacuation, exposure, and release to the atmosphere are intermittently performed, continuous production cannot be performed, and the processing speed becomes slow.

  On the other hand, as illustrated in FIGS. 3 and 4, when the continuous exposure apparatuses 30 and 40 that can continuously expose the substrate are used, the processing speed is faster than the single wafer processing type exposure apparatus, and the continuous There is an advantage that efficient production becomes possible.

  A continuous exposure apparatus 30 shown in FIG. 3 includes a cylindrical drum 31 made of a material that transmits light used for exposure in a photographic method, an exposure mask portion 32 provided on the outer peripheral wall of the cylindrical drum 31, and the inside of the cylindrical drum 31. And an exposure light source 33 disposed on the surface of the cylindrical drum 31, and the substrate 34 wound around the cylindrical drum 31 is exposed by light emitted from the light source 33 inside the cylindrical drum 31. In the continuous exposure apparatus 30, a light source cover 35 having an opening 36 that transmits light in a specific irradiation direction can be provided around the exposure light source 33. The pattern for exposing the substrate 34 (that is, the pattern corresponding to the FSS element) is determined by the pattern of the portion of the exposure mask portion 32 that transmits light. The exposure mask portion 32 is disposed on the cylindrical drum 31 by, for example, being provided on the surface (inner surface or outer surface) of the outer peripheral wall of the cylindrical drum 31 or being inserted or sandwiched inside the outer peripheral wall. FIG. 3 is a diagram illustrating a case where the exposure mask portion 32 is provided on the outer surface of the outer peripheral wall of the cylindrical drum 31.

  In this continuous exposure apparatus 30, the cylindrical drum 31 rotates at the same speed as the base material 34 that is continuously transferred, so that each part of the base material 34 is exposed at a place where the cylindrical drum 31 is wound. In the meantime, the pattern of the exposure mask portion 32 with respect to the base material 34 (the pattern of the light transmitting portion and the light shielding portion) is not shifted, and the exposure for the required time can be continued. The light source 33 used in the exposure apparatus can be appropriately selected depending on the spectral characteristics and sensitivity of the silver halide emulsion contained in the silver halide emulsion layer. For example, a tungsten lamp, an ultraviolet lamp, a fluorescent lamp, a xenon lamp, a metal halide A lamp or the like can be used. At the time of exposure, the light source cover 35 does not rotate, and the opening 36 always faces in a certain direction (the right direction in FIG. 3). Is blocked by the light source cover 35. That is, the exposure of the base material 34 by the light source 33 of the continuous exposure apparatus 30 is performed within a certain range 37 in which the base material 34 is wound around the surface of the cylindrical drum 31 on the transfer path. By adjusting the exposure light amount and the irradiation time in accordance with the above, the optimum light amount can be reliably irradiated.

On the other hand, the continuous exposure apparatus 40 shown in FIG. 4 includes a cylindrical drum 41, an exposure mask film 42 on which a pattern corresponding to the FSS element is formed, and an exposure light source 43 disposed outside the cylindrical drum 41. The apparatus is configured to irradiate light from the outside of the cylindrical drum 41 to the base material 44 wound around the cylindrical drum 41 and expose the base material 44 through the exposure mask film 42.
The exposure mask film 42 is formed by forming a pattern to be a mask on a transparent resin film by a known method such as a photolithographic method using reduced exposure. 41 is used for exposure. Thereafter, the exposure mask film 42 is cut off from the base material 44, wound up, and used repeatedly.
When the light source 43 is outside the cylindrical drum 41, the transparency of the cylindrical drum 41 is not particularly limited, and may be opaque.

  In the continuous exposure apparatus 40, a light source cover 45 having an opening 46 that transmits light in a specific irradiation direction can be provided around the light source 43 for exposure. Thereby, the exposure of the base material 44 by the light source 43 is performed within a certain range 47 in which the base material 44 is wound around the surface of the cylindrical drum 41 on the transfer path, so that the exposure light amount and the irradiation time are controlled. Can be performed reliably. Here, as the light source 43, the same light source 33 as that of the above-described continuous exposure apparatus 30 can be used.

Since the continuous exposure apparatus 40 shown in FIG. 4 continuously transfers the superposed base material 44 and the exposure mask film 42 while being wound around the cylindrical drum 41, it can be transferred while applying an appropriate tension to both. The transfer speed is easy to control, and the pattern of the exposure mask film 42 on the substrate 44 (light-transmitting portion and light-shielding portion) is exposed while the portions of the substrate 44 are exposed at the portions wound around the cylindrical drum 41. Therefore, the exposure for the required time can be continued.
In addition to the continuous exposure apparatuses 30 and 40 exemplified above, for example, the superimposed transparent base material and exposure mask film are continuously exposed using a light source while being continuously conveyed along a linear path. An apparatus or the like can also be used. Further, the number of light sources for exposure is not particularly limited, and a plurality (in a plurality of locations) may be provided as necessary.

  According to the present invention, a frequency selective shielding type electromagnetic wave shield that is supplied by a wide sheet (particularly in a continuous roll sheet state) for covering a large area such as a window glass of a large building, which cannot be handled by a conventional manufacturing method. Since the material can be manufactured, it is greatly beneficial for quality improvement and cost reduction.

It is a front view which shows schematic structure of the electromagnetic wave shielding material of a frequency selective shielding type. (A)-(k) is a partial enlarged front view which shows the example of the pattern of a FSS element, respectively. It is the schematic which shows an example of a continuous exposure apparatus. It is the schematic which shows another example of a continuous exposure apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Frequency selective shielding type electromagnetic wave shielding material, 2 ... Transparent base material, 3 ... FSS element, 30 ... Continuous exposure apparatus, 31 ... Cylindrical drum, 32 ... Exposure mask part, 33 ... Light source for exposure, 34 ... Base material, 35 ... Light source cover, 40 ... Continuous exposure device, 41 ... Cylindrical drum, 42 ... Exposure mask film, 43 ... Light source for exposure, 44 ... Base material, 45 ... Light source cover.

Claims (7)

A frequency selective shielding type electromagnetic shielding material in which an FSS element made of a fine line pattern for shielding electromagnetic waves of a predetermined frequency is disposed on at least one surface of a transparent substrate,
The frequency selective shielding electromagnetic wave shielding material, wherein the metal layer of the FSS element is composed of a developed silver layer produced by a photographic method.   The frequency selective shielding electromagnetic wave shielding material according to claim 1, wherein a line width of the metal layer is 15 to 60 μm.   3. The frequency selective shielding type according to claim 1, wherein the developed silver layer is a developed silver layer produced by a positive photographic process or a developed silver layer produced by a negative photographic process. Electromagnetic shielding material. A method for producing a frequency selective shielding type electromagnetic shielding material in which an FSS element comprising a thin line pattern for shielding electromagnetic waves of a predetermined frequency is disposed on at least one surface of a transparent substrate,
A substrate having a layer containing a material that deposits metallic silver by exposure and development is exposed to at least one surface of the transparent substrate, and then developed, whereby the pattern of the FSS element is generated by the developed silver layer. A method for producing an electromagnetic wave shielding material of frequency selective shielding type, comprising at least the step of: A method for producing a frequency selective shielding type electromagnetic shielding material in which an FSS element comprising a thin line pattern for shielding electromagnetic waves of a predetermined frequency is disposed on at least one surface of a transparent substrate,
By exposing a base material provided with a layer containing a substance capable of depositing metallic silver by exposure and development to at least one surface of a long transparent base material using a continuous exposure apparatus, and then developing, A method for producing an electromagnetic wave shielding material of frequency selective shielding type, comprising at least a step of generating a pattern of an FSS element by a developed silver layer.   The continuous exposure apparatus includes a cylindrical drum made of a material that transmits light used for exposure, an exposure mask portion provided on an outer peripheral wall of the cylindrical drum, and an exposure light source disposed inside the cylindrical drum. 6. The method of manufacturing a frequency selective shielding type electromagnetic shielding material according to claim 5, wherein the transparent base material wound around the cylindrical drum is irradiated with light from the inside of the cylindrical drum. .   The continuous exposure apparatus includes a cylindrical drum, an exposure mask film on which a continuous pattern is formed, and an exposure light source disposed outside the cylindrical drum, and a transparent substrate wound around the cylindrical drum. 6. The method of manufacturing a frequency selective shielding type electromagnetic shielding material according to claim 5, wherein the material and the exposure mask film irradiate light from the outside of the cylindrical drum.

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