JP2008277428A - Electromagnetic shielding material and display panel - Google Patents

Abstract

In an electromagnetic wave shielding material, an electromagnetic wave shielding material with improved electromagnetic wave shielding performance and contrast and a method for manufacturing the electromagnetic wave shielding material are provided.
An electromagnetic wave shielding material having a fine line pattern formed on a transparent substrate, wherein the fine line patterns are made of a thin conductive metal layer, and the transparent substrate An electromagnetic wave shielding material 10 is provided which is formed on both surfaces of the material 14. The two fine line patterns 13 and 15 formed on both surfaces of the transparent substrate 14 are lines of both the fine line patterns 13 and 15 when viewed from a direction perpendicular to one surface of the transparent substrate 14. It is preferable that the width and the pitch are arranged at substantially overlapping positions.
[Selection] Figure 2

Description

  The present invention relates to an electromagnetic wave shielding material. More specifically, in an electromagnetic shielding material used for an optical filter for various displays such as CRT and PDP (plasma display), which is a high performance electromagnetic shielding material, the electromagnetic shielding performance and contrast are improved. The present invention relates to an electromagnetic shielding material and a display panel.

  In recent years, in various displays such as CRT and PDP (plasma display), electromagnetic waves generated from the front of the display adversely affect the human body and malfunction of surrounding electronic devices has become a problem. Along with the clearness of the display, countermeasures against the influence of the display on the surroundings are becoming increasingly important.

  Conventionally, various transparent conductive films and electromagnetic wave shielding films have been developed in response to the requirement that electromagnetic waves generated from a display leak outside and prevent adverse effects on the human body. Known electromagnetic shielding materials are roughly classified into two types: an electromagnetic shielding material made of a transparent conductive film and an electromagnetic shielding material made of a conductive metal mesh. Among these, the electromagnetic shielding material using a transparent conductive film is superior in transparency to the electromagnetic shielding material using a metal mesh, but has a large surface resistivity and inferior electromagnetic shielding performance. For this reason, in the use which shields the electromagnetic waves from the apparatus which generate | occur | produces strong electromagnetic waves, such as PDP, the electromagnetic wave shielding material by a metal mesh is preferable.

Furthermore, as a method for producing an electromagnetic wave shielding material using a conductive metal mesh, the following methods (1) to (3) are exemplified.
(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 conductive metal pattern is formed by a photolithographic method (see, for example, Patent Document 1).
(2) A printing-plating method in which a conductive metal paste is printed on a transparent substrate and then plated to form a conductive metal pattern (see, for example, Patent Document 2).
(3) A photographic silver-plating method for forming a conductive metal pattern by forming a fine line pattern with metallic silver developed by a photographic method and then physically developing and / or plating the metallic silver (for example, Patent Document 3) And Patent Document 4).

  Then, there are two methods shown in the following (a) and (b) for forming a mesh pattern with metallic silver by a photographic manufacturing 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 (see, for example, Patent Document 3). 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 4). 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).

Further, in Patent Document 5, when a fine mesh pattern of a copper thin film is formed by the etching method of (1) above, the blackened surface of the metal foil and one surface of the transparent substrate are bonded to the adhesive layer. After bonding, the metal foil is etched to form a metal layer pattern, and the surface and side surfaces of the metal layer pattern are blackened.
Japanese Patent Laid-Open No. 10-075087 JP 11-170420 A JP 2004-221564 A International Publication No. 2004/007810 JP 2002-009484 A

In the etching method (1), it is a problem from the viewpoint of saving resources that only a very small portion which becomes a thin line portion is left by etching and most of the other metals are dissolved and removed. Furthermore, there is a problem that the manufacturing cost increases because the cost for the waste liquid treatment of the etching treatment liquid increases. In addition, when a metal thin film is deposited, there is a problem that it cannot be easily manufactured because a huge equipment cost is required.
In the printing-plating method (2), it is difficult to reduce the line width of the mesh pattern to 30 μm or less, and there is a problem in that the adhesiveness between the transparent substrate and the mesh pattern is poor and is easily peeled off.

In the photographic silver-plating method of (3) above, high electromagnetic shielding properties are obtained, and there is no restriction on the dimensions of the transparent base material, so that it can be produced with a roll-to-roll and the productivity is very high. This is a preferred production method.
However, even with an optical filter using an electromagnetic shielding material with a conductive metal mesh pattern by photographic silver-plating method, the fine line density of the mesh pattern is increased in order to improve electromagnetic shielding properties. However, there is a problem that the total light transmittance is lowered.

  By the way, according to Patent Document 5, both surfaces and side surfaces of the metal layer pattern are blackened, so that the emitted light from the display screen of the PDP is reflected by the surface of the shield material and returns to the display screen, and the light of the shield material It is disclosed that the transmittance of the liquid crystal is reduced and the visibility of the display screen is prevented from deteriorating. However, as described above, the patterning of the metal layer by the etching method of Patent Document 5 has problems from the viewpoint of resource saving and manufacturing cost.

  For this reason, in the PDP, a clear image is displayed without attenuating the light emission intensity of the PDP, and therefore, a manufacturing method that leads to resource saving is used, and the total light transmittance is high and the luminance is less reduced. There is a need for an electromagnetic shielding material that improves shielding performance and contrast.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the electromagnetic wave shielding material and display panel which aimed at the improvement of electromagnetic wave shielding performance and contrast in an electromagnetic wave shielding material.

  In order to solve the above problems, the present invention is an electromagnetic shielding material formed by forming a fine line pattern on a transparent substrate, wherein the fine line pattern is a pattern comprising a thinned conductive metal layer, Provided is an electromagnetic wave shielding material characterized by being formed on both surfaces of a transparent substrate.

  The two fine line patterns formed on both surfaces of the transparent substrate are located at positions where the line widths and pitches of both fine line patterns substantially overlap when viewed from a direction perpendicular to one surface of the transparent substrate. It is preferable that it is disposed.

The fine line pattern is preferably a metal layer composed of a developed silver layer produced by a photographic process.
The fine line pattern is a metal layer composed of a developed silver layer produced by a photographic process, and the fine line pattern on at least one surface has a metal plating layer further laminated on the developed silver layer. It is preferable to become.
The fine line pattern is preferably a metal mesh pattern.

The metal plating layer is preferably an electroless plating layer and / or an electrolytic plating layer.
The outermost surface of the metal layer is preferably blackened.
In the fine line pattern, it is preferable that the metal layer has a line width of 15 to 80 μm and a thickness of 0.05 to 80 μm.

  The developed silver layer is preferably a developed silver layer produced by a positive photographic method in which developed silver appears in a portion that is not exposed.

  The present invention also provides a display panel characterized in that the electromagnetic wave shielding material described above is used for an optical filter.

According to the present invention, since a fine line pattern made of a metal layer is formed on both surfaces of a transparent substrate, a high-performance electromagnetic shielding material can be obtained.
Also, the two fine line patterns formed on both surfaces of the transparent substrate are arranged so that the line width and pitch of both fine line patterns are substantially overlapped when viewed from a direction perpendicular to one surface of the transparent substrate. Therefore, it is possible to prevent the light transmittance from the display screen from being lowered and the visibility of the display screen from being deteriorated.

  Further, by blackening the outermost surface of the fine line pattern made of two metal layers formed on both surfaces of the transparent substrate, the light from the display is reflected on the surface of the fine line pattern made of the metal layer. And the contrast of the display screen can be increased.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a schematic partial cross-sectional view showing an electromagnetic wave shielding material according to a first embodiment of the present invention, showing an electromagnetic wave shielding material in which fine line patterns composed of developed silver layers are formed on both surfaces of a transparent substrate. .
FIG. 2 shows an electromagnetic wave shielding material according to a second embodiment of the present invention, in which fine line patterns composed of a developed silver layer are formed on both surfaces of a transparent base material, and one fine line pattern is formed on the developed silver layer. It is a general | schematic fragmentary sectional view which shows the electromagnetic wave shielding material by which a metal plating layer is further laminated | stacked on it.
FIG. 3 is a schematic partial cross-sectional view showing an example of a conventional electromagnetic shielding material.

The electromagnetic shielding material 1 according to the first embodiment of the present invention shown in FIG. 1 has an electromagnetic shielding pattern 3, 3 made of a thin conductive metal layer on both surfaces of a transparent substrate 4. Are formed on both sides.
By forming the electromagnetic wave shielding patterns 3 and 3 on both surfaces of the transparent base material 4, compared to forming the electromagnetic wave shielding pattern only on one surface of the conventional transparent base material, the high performance electromagnetic wave shielding material Can be obtained.
Further, the two fine line patterns 3 and 3 formed on both surfaces of the transparent substrate 4 are viewed from the direction perpendicular to one surface of the transparent substrate 4, and the line width and pitch of both fine line patterns. Are disposed at substantially overlapping positions. This prevents the light emitted from the display screen of the PDP from being reflected on the surface of the shield material and returning to the display screen, thereby preventing the light transmittance of the shield material from being lowered and the visibility of the display screen from being deteriorated. it can.
The fine line patterns 3 and 3 are preferably metal layers composed of developed silver layers produced by a photographic process. The surface of the developed silver layer is preferably blackened.

The electromagnetic shielding material 10 of the second embodiment of the present invention shown in FIG. 2 is formed with metal layers 13 and 13 composed of developed silver layers produced by a thin photographic method on both surfaces of the transparent substrate 14. Further, metal plating layers 15 and 15 are further laminated on the developed silver layer of at least one fine line pattern.
The two fine line patterns 13 and 13 formed on both surfaces of the transparent substrate 14 are substantially the same in width and pitch of both fine line patterns as viewed from a direction perpendicular to one surface of the transparent substrate 14. It is arranged at the overlapping position. This prevents the light emitted from the display screen of the PDP from being reflected on the surface of the shield material and returning to the display screen, thereby preventing the light transmittance of the shield material from being lowered and the visibility of the display screen from being deteriorated. it can. The outermost surface of the metal plating layer is preferably blackened.
FIG. 2 shows an electromagnetic wave shielding material in which a metal plating layer 15 is laminated on a metal layer 13 composed of a developed silver layer produced by a photographic method only on one surface of a transparent substrate. In the embodiment of the present invention, an electromagnetic shielding material in which a metal layer composed of a developed silver layer produced by a photographic method is formed on both sides of a transparent substrate, and a metal plating layer is further laminated thereon. Is also included.

(Metal layer pattern manufacturing method)
The method for producing a fine line pattern comprising a metal layer used as an electromagnetic wave shielding material in the present invention includes developed silver at a portion not exposed between two different silver salt photographic development methods (positive photographic production method and negative photographic production method). A method of forming a fine line pattern made of developed silver using a positive developing method in which is developed.
By using a positive photographic method, a fine line pattern formed of a developed silver layer formed on one side (A side) of a transparent substrate is used as a mask, and the other side (B side is designated as A side). ) After exposure, it is possible to generate the same fine line pattern as that on the A side on the B side with the developed silver layer.
By this positive photographic process, for the first time, two fine line patterns formed on both surfaces of the transparent substrate can be seen from the direction perpendicular to the one surface of the transparent substrate. It can be set in the state where the width and the pitch are substantially overlapped.

In the present invention, it is preferable to form fine line patterns made of developed silver by this positive photographic process on both surfaces of a transparent substrate. Furthermore, it is also preferable to use a method of forming a metal plating layer by plating on a fine line pattern made of developed silver.
Hereinafter, a method for producing a fine line pattern that can be used as an electromagnetic shielding material based on the positive photographic method used in the present invention will be described.

(Transparent substrate)
The transparent substrates 4 and 14 used in the present invention are preferably those having transparency in the visible region and generally having a total light transmittance of 90% or more. Especially, the resin film which has flexibility is used suitably at the point which is easy to handle. Specific examples of transparent resin films used for the transparent substrates 4 and 14 include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic resins, epoxy resins, fluororesins, silicone resins, and polycarbonate resins. Single layer film having a thickness of 50 to 300 μm made of diacetate resin, triacetate resin, polyarylate resin, polyvinyl chloride, polysulfone resin, polyether sulfone resin, polyimide resin, polyamide resin, polyolefin resin, cyclic polyolefin resin, etc. A composite film having a plurality of layers made of the transparent resin may be mentioned.

(Formation of fine line pattern on both sides of transparent substrate)
The method for producing a fine line pattern made of a conductive metal applicable to the present invention is to form a fine line pattern with metallic silver developed by a positive photographic method. In addition, a method for producing a fine line pattern made of a conductive metal applicable to the present invention is a metal layer comprising a developed silver layer produced by a positive photographic process and a metal plating layer laminated thereon. In the present invention, the present invention includes (a) a negative exposure / development method and (b) a positive exposure / development method. A development method is preferably used.

In the present invention, as a method for producing an electromagnetic wave shielding material formed by forming a fine line pattern on both surfaces of a transparent substrate, the fine line pattern is obtained by using a positive photographic method in which developed silver appears in a portion that is not exposed. A developed silver mesh pattern is generated.
A substrate provided with a layer containing a substance that deposits metallic silver by exposure and development on one surface (referred to as surface A) of the transparent substrate is exposed using a previously prepared exposure mask, and then developed. Then, a step of generating a fine line pattern composed of a developed silver layer, and then, a layer containing a substance that deposits metallic silver by exposure and development is provided on the other surface (referred to as B surface) of the transparent substrate. Next, using the fine line pattern formed of the developed silver layer formed on the A side as a mask, exposing from the A side, and developing, the same fine line pattern as the A side is formed on the B side. And a method for producing an electromagnetic wave shielding material including at least a step of producing a developed silver layer.

  Moreover, in this invention, the exposure mask prepared beforehand is used for the base material provided with the layer containing the substance which deposits metal silver by exposure and image development on one side (it is set as A surface) of a transparent base material. A step of generating a fine line pattern composed of a developed silver layer by exposing to light and then developing, and then depositing metallic silver on the other surface (referred to as surface B) of the transparent substrate by exposure and development The step of providing a layer containing a substance, and then using the fine line pattern formed of the developed silver layer formed on the A surface as a mask, exposing from the A surface side, and developing the A surface on the B surface side. A step of generating the same fine line pattern with the developed silver layer, and a plating step of forming a metal plating layer on the fine line pattern composed of the developed silver layer generated on both the A side and the B side, Of electromagnetic shielding material containing at least It is carried out by the law.

Hereinafter, development of a fine line pattern made of developed silver by developing a positive photographic method (DTR method) in which developed silver appears in a non-exposed portion, and developing silver by a positive photographic method (DTR method) in which developed silver appears in a non-exposed portion. A method for producing a fine line pattern made of a metal layer having a plating layer formed thereon 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 transparent substrate surface. In order to develop developed silver by exposure and development using the DTR method on both sides of the transparent substrate as in the present invention, after forming a physical development layer on one side, a physical development nucleus is formed on the other side. A layer may be provided to develop developed silver by exposure and development.

  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. The fine particle layer of these physical development nuclei can be provided on the transparent substrate by a vacuum deposition method, a cathode sputtering method, a coating method 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 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 can be provided between the adhesive layer and the physical development nucleus layer. it can.

  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 depositing 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 formed in this order on a transparent substrate, or another paper or plastic resin. There is a method of supplying a soluble silver complex salt from a silver halide emulsion layer provided on a substrate such as a film. 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.

(Exposure method)
When an electromagnetic wave shielding material is produced using a photosensitive material in which a silver halide emulsion layer is coated directly on the physical development nucleus layer or via an intermediate layer, it is usually an arbitrary one such as a mesh pattern. An exposure mask with a fine line pattern and the photosensitive material are in close contact with each other, or a digital image with an arbitrary fine line pattern is scanned and exposed to the photosensitive material with various laser beam output machines.

  The silver halide emulsion layer is sensitive to various light sources. As one method for producing an electromagnetic wave shielding material, for example, formation of physically developed silver having a fine line pattern such as a mesh shape can be mentioned. In this case, the silver halide emulsion layer is exposed in a fine line pattern. As an exposure method, a method of exposing a fine line pattern transmission original and a silver halide emulsion layer in close contact with each other, or scanning exposure using various laser beams. There are ways to do this. 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.

(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 fine line pattern. A single-wafer processing type exposure apparatus uses a single-wafer exposure mask (photomask) on which a predetermined mask pattern is formed, and a transparent layer provided with a layer containing a substance that deposits metallic silver by transparent exposure and development. The roll sheet fed from the base fabric roll of the base material is intermittently fed to the exposure apparatus, the inside of the apparatus is evacuated, the exposure mask and the base material are brought into close contact with each other to eliminate a gap, and then exposed with, for example, ultraviolet rays. In a single wafer processing type exposure apparatus, vacuum exhaust, exposure, and release to the atmosphere are intermittently performed, so that the processing speed is slow and a seamless continuous pattern cannot be obtained.

  On the other hand, a continuous exposure apparatus capable of continuously forming a fine line pattern can also be used. That is, the transparent sheet is exposed by using a continuous exposure apparatus, and then developed by using a continuous exposure apparatus, and the transparent sheet is rolled out from a raw roll of a transparent substrate provided with a layer containing a substance that deposits metallic silver by exposure and development. A fine line pattern made of developed silver is generated at a certain interval in the longitudinal direction of the substrate.

  The continuous exposure apparatus is, for example, a cylindrical drum made of a material that transmits light used for exposure in a photographic process, an exposure mask portion provided on the outer peripheral wall of the cylindrical drum, and an exposure mask disposed in the cylindrical drum. And a device for exposing a transparent substrate wound around the cylindrical drum by light emitted from the light source inside the cylindrical drum. In this continuous exposure apparatus, a light source cover having an opening that transmits light in a specific irradiation direction can be provided around the light source for exposure. The pattern for exposing the transparent substrate is determined by the pattern of the portion that transmits light in the exposure mask portion. The exposure mask portion is disposed on the cylindrical drum by, for example, being provided on the surface (inner surface or outer surface) of the outer peripheral wall of the cylindrical drum, or being inserted or sandwiched inside the outer peripheral wall.

  In this continuous exposure apparatus, since the cylindrical drum rotates at the same speed as the transparent substrate that is continuously transferred, the transparent drum is transparent while the portions of the transparent substrate are exposed at the portions wound around the cylindrical drum. It is possible to continue the exposure for the required time without shifting the pattern of the exposure mask portion with respect to the base material (the pattern of the light transmitting portion and the light shielding portion). The light source 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, etc. are used. can do.

At the time of exposure, the light source cover does not rotate, and the opening portion is always directed in a certain direction, so that light from the light source is blocked by the light source cover at a portion where the transparent substrate is away from the surface of the cylindrical drum. That is, the exposure of the transparent base material by the light source of the exposure apparatus is performed within a certain range in which the transparent base material is wound around the surface of the cylindrical drum on the transfer path, so that the control of the light amount and time of exposure is ensured. Can be done.
The continuous exposure apparatus has an advantage that the processing speed is higher than that of a conventional single wafer processing type exposure apparatus and a continuous pattern having no joints can be obtained.

(Development method)
Halation at any position on the transparent 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 Or a dye or pigment for preventing irradiation may be contained.

  When producing an electromagnetic shielding material using a photosensitive material in which a silver halide emulsion layer is coated directly on the physical development nucleus layer or via an intermediate layer, an arbitrary fine line pattern such as a mesh pattern is used. After exposing a transparent original and the photosensitive material in close contact, or by scanning and exposing a digital image of an arbitrary fine line pattern onto the photosensitive material with various laser light output machines, in the presence of a soluble silver complex salt forming agent and a reducing agent. Silver complex diffusion transfer development (DTR development) occurs by processing in an alkaline solution, the silver halide in the unexposed area is dissolved to form a silver complex salt, which is reduced on the physical development nuclei, and metallic silver is precipitated to form a fine line. A physically developed silver thin film with a pattern can be obtained. 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 a physically developed silver thin film having a fine line 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 the soluble silver complex salt is supplied from a silver halide emulsion layer provided on a substrate different from the transparent substrate on which the physical development nucleus layer is coated, the silver halide emulsion layer is exposed as described above. After that, a transparent substrate coated with a physical development nucleus layer and another photosensitive material coated with a silver halide emulsion layer are superposed in an alkaline solution in the presence of a soluble silver complexing agent and a reducing agent. After several tens of seconds to several minutes after taking out from the alkaline solution, the both are removed to obtain a physically developed silver thin film having a fine line 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-mentioned soluble silver complex salt forming agent and reducing agent may be applied to the transparent substrate together with the physical development nucleus layer, added to the silver halide emulsion layer, or contained in the alkaline solution. It may be allowed to be contained, and may be further contained in a plurality of positions, but is preferably contained at least in 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, transporting while immersing a transparent substrate provided with a physical development nucleus layer and a silver halide emulsion layer in an alkaline solution stored in a large amount in a tank. For example, about 40 to 120 ml of an alkali solution per square meter is coated on the silver halide emulsion layer.

(Thin line pattern with developed silver)
As described above, there are fine line patterns in which, for example, fine lines having a line width of about 10 to 100 μm are provided in a grid pattern in the vertical and horizontal directions. If the narrow line width is reduced and the interval between the gratings is increased, the translucency increases. However, the conductivity decreases, and conversely, if the fine line width is increased to reduce the lattice spacing, the translucency is decreased and the conductivity is increased. The silver image obtained by physical development of an arbitrary fine line pattern formed on one surface of the transparent substrate according to the present invention has a translucency with a total light transmittance of 50% or more and a conductivity with a surface resistivity of 10 ohms / □ or less. It is difficult to satisfy at the same time.
However, by forming fine line patterns made of developed silver on both surfaces of the transparent substrate, the surface low efficiency can be reduced to 10 ohms / square or less.
Further, the two fine line patterns formed on both surfaces of the transparent substrate by the positive photographic method of the present invention are both fine line patterns as viewed from a direction perpendicular to one surface of the transparent substrate. Therefore, it is possible to satisfy the translucency with a total light transmittance of 50% or more.

By the way, the silver image by the physical development itself forms a silver image because the metallic silver particles forming the silver image obtained after the development processing are extremely small and the amount of the hydrophilic binder present in the silver image is extremely small. A silver image is formed in a state where the metallic silver particles to be close to the close-packed state have electrical conductivity.
For this reason, it is possible to further improve electromagnetic wave shielding performance by performing electroless plating or electrolytic plating with a metal such as copper or nickel on the silver image.
In order to improve the total light transmittance of the fine line pattern from the metal layer, it is necessary to sufficiently increase the area of the light transmission portion between the fine lines with respect to the area of the region where the fine lines are provided. For this reason, it is preferable that the space | interval of a thin wire | line is 100-900 micrometers, More preferably, it is 150-700 micrometers.

(Plating on developed silver)
The thickness of the fine line pattern obtained by metal plating on the developed silver can be arbitrarily changed depending on the desired properties, but is in the range of 0.05 to 80 μm, preferably 0.2 to 30 μm.
When the electromagnetic wave shielding material of the present invention is used as an electromagnetic wave shielding material for an optical filter for display, the mesh pattern made of a metal layer has a fine line width of 15 to 80 μm, a thickness of 0.2 to 30 μm, and a pitch of 200 to 300 μm. Shielding of 30 dB or more over a wide frequency band such as 30 MHz to 1,000 MHz with excellent light transmission performance and conductivity performance of total light transmittance of 50% or more and surface resistivity of 1 ohm / □ or less The effect can be demonstrated.

  The metal plating applied on the developed silver can be any of electroless plating, electrolytic plating, or a combination of both.

(Plating method)
In the present invention, the method for forming the metal plating layer laminated on the developed silver layer produced by the photographic method is as follows.
Fine line patterns 13 and 13 made of developed silver produced by a photographic manufacturing method are formed on both surfaces of the transparent substrate 14, and copper (Cu) and / or nickel (Ni) is plated on the fine line patterns 13 and 13. To do.
In the present invention, the metal plating method can be performed by a known method. For example, the electrolytic plating method is a conventionally known method such as copper, nickel, silver, gold, solder, or a multilayer or composite system of copper / nickel. For these, reference can be made to documents such as “Surface Treatment Technology Overview; Technical Data Center, Inc., December 21, 1987, first edition, pages 281 to 422”.
It is preferable to use copper and / or nickel for reasons such as easy plating, excellent electrical conductivity, plating on a thick film, and low cost.

(Electroless copper plating)
The electroless copper plating solution preferably has a metal copper (Cu) concentration of 0.5 to 10 g / liter, more preferably 2 to 3 g / liter.
As temperature of a plating process liquid, 30-80 degreeC is preferable, More preferably, it is 40-50 degreeC. If the temperature of the plating solution is lower than 30 ° C., the copper deposition rate is slow, and if it is 80 ° C. or higher, the energy cost increases, which is not preferable.
The plating thickness is preferably 0.01 to 1 μm, and more preferably 0.05 to 0.2 μm. Further, the electroless copper plating solution may be any solution as long as it is a known plating solution.

(Electrolytic copper plating)
In the case of electrolytic copper plating, any plating solution such as copper sulfate, copper cyanide, and copper pyrophosphate may be used, but copper sulfate is preferable from the viewpoint of cost. In these electrolytic copper plating solutions, the concentration of copper (Cu) may be set to an appropriate concentration.
When using a copper sulfate plating bath, the sulfuric acid concentration is preferably 20 to 400 g / liter, more preferably 70 to 300 g / liter. If the sulfuric acid concentration is lower than 20 g / liter, the plating solution becomes unstable, and if it is higher than 300 g / liter, abnormalities occur in the plating particles.
The plating temperature is preferably 10 to 60 ° C, more preferably 20 to 40 ° C. If the temperature of the plating solution is lower than 10 ° C., the plating time is increased and the cost is increased, and if it is higher than 60 ° C., the plating appearance is deteriorated.
The current density of electrolytic plating is preferably 0.05 to 20 A / cm ² , more preferably 0.5 to 8 A / cm ² . When the current density of electrolytic plating is lower than 0.05 A / cm ² , the plating time becomes longer and the cost increases. Moreover, when the current density of electrolytic plating is higher than 20 A / cm < ² >, since the external appearance of a plating film will worsen, it is unpreferable.

(Electrolytic nickel plating)
When performing electrolytic nickel plating, any plating bath such as watt bath (nickel sulfate, nickel chloride, boric acid), nickel sulfamate bath (nickel sulfamate, nickel chloride, boric acid), etc. But you can.

(Blackening treatment)
The outermost surface of the developed silver layer or metal plating layer is preferably blackened to prevent reflection of light due to the gloss of the metal.
When a fine line pattern made of developed silver by a positive photographic method is used as an electromagnetic shielding material, the DTR method is used to suppress the reflection of light from the display on the surface of the fine line pattern made of a metal layer and increase the contrast of the display screen. It is necessary to blacken the surface of the metallic silver layer formed by the above.
In the DTR method, after exposure to an arbitrary fine line pattern, silver complex diffusion transfer development (DTR development) occurs by processing in an alkaline solution in the presence of a soluble silver complex salt forming agent and a reducing agent. The silver halide is dissolved to form a silver complex salt, which is reduced on the physical development nuclei to deposit metallic silver to obtain a physically developed silver thin film having a fine line pattern. The exposed portion is chemically developed in the silver halide emulsion layer to become blackened silver. After the development, the silver halide emulsion layer and the intermediate layer, or the protective layer provided as necessary, are removed by washing, and the metal silver layer having a fine line pattern is exposed on the surface. This metal silver layer is again subjected to a halogenation treatment to obtain a blackened silver black.

In addition, when a fine line pattern of a metal layer composed of a developed silver layer produced by a positive type photographic method and a metal plating layer laminated thereon is used as an electromagnetic shielding material, the light from the display is a fine line composed of a metal layer. In order to suppress reflection on the surface of the pattern and increase the contrast of the display screen, it is necessary to blacken the outermost surface of the plating layer.
As a method of blackening treatment on the surface of nickel plating, there is no particular limitation on the type of blackening treatment film and the composition of the blackening treatment liquid to be used. As a preferable example, when black nickel is used, sulfuric acid of the blackening treatment liquid is used. The concentration is preferably 10 to 50 g / liter, and more preferably 20 to 40 g / liter. When the concentration of nickel sulfate is lower than 10 g / liter, plating deposition is delayed and the cost is increased, and when it is higher than 50 g / liter, the finished color of the blackening treatment is not stable.

ADVANTAGE OF THE INVENTION According to this invention, in the electromagnetic wave shielding material, the electromagnetic wave shielding material which aimed at the improvement of electromagnetic wave shielding performance and contrast, and its manufacturing method can be provided.
In particular, the two fine line patterns formed on both surfaces of the transparent substrate are substantially overlapped with the line width and pitch of both fine line patterns when viewed from a direction perpendicular to one surface of the transparent substrate. Since it is disposed, it is possible to prevent the light transmittance from the display screen from being lowered and the visibility of the display screen from being deteriorated.
Furthermore, by blackening the outermost surfaces of the two fine line patterns formed on both surfaces of the transparent substrate, light from the display is prevented from being reflected on the surface of the metal mesh, and the contrast of the display screen is increased. be able to.

In this invention, it is a general | schematic fragmentary sectional view which shows the electromagnetic wave shielding material whose thin wire | line pattern is a metal layer which consists of the image development silver layer produced | generated by the photographic manufacturing method. In the present invention, one of the fine line patterns is a schematic partial cross-sectional view showing an electromagnetic wave shielding material which is a metal layer composed of a developed silver layer produced by a photographic method and a metal plating layer laminated thereon. It is a schematic sectional drawing which shows an example of the conventional electromagnetic wave shielding material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 ... Electromagnetic wave shielding material of this invention, 3,13 ... Metal layer which consists of developed silver layer produced | generated by the photographic manufacturing method, 4,14 ... Transparent base material, 15 ... Metal mesh by plating, 20 ... Electromagnetic wave by a prior art Shielding material, 22 ... metal mesh, 24 ... transparent substrate.

Claims (8)

  An electromagnetic shielding material formed by forming a fine line pattern on a transparent substrate, wherein the fine line pattern is a pattern composed of a thinned conductive metal layer and is formed on both surfaces of the transparent substrate. An electromagnetic shielding material characterized by having   The two fine line patterns formed on both surfaces of the transparent substrate are located at positions where the line widths and pitches of both fine line patterns substantially overlap when viewed from a direction perpendicular to one surface of the transparent substrate. The electromagnetic shielding material according to claim 1, wherein the electromagnetic shielding material is disposed.   The electromagnetic wave shielding material according to claim 1, wherein the fine line pattern is a metal layer composed of a developed silver layer generated by a photographic manufacturing method.   The fine line pattern is a metal layer composed of a developed silver layer generated by a photographic process, and the fine line pattern on at least one surface is formed by further laminating a metal plating layer on the developed silver layer. The electromagnetic wave shielding material according to claim 1 or 2.   The electromagnetic shielding material according to claim 4, wherein the metal plating layer is an electroless plating layer and / or an electrolytic plating layer.   The electromagnetic wave shielding material according to claim 1, wherein the outermost surface of the metal layer is blackened.   The electromagnetic wave shielding material according to any one of claims 3 to 6, wherein the developed silver layer is a developed silver layer produced by a positive photographic method in which developed silver appears in a portion not exposed to light.   A display panel comprising the electromagnetic shielding material according to claim 1 as an optical filter.

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