JP2010080693A - Electromagnetic wave shield filter, and image display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave shield filter that has no remaining air bubble, excellent adhesive strength to another optical filter, and superior production efficiency. <P>SOLUTION: The electromagnetic wave shield filter has a transparent base 1, a metal mesh layer provided on the transparent base, and an adhesive layer 7 provided on the metal mesh layer to fill unevenness of a mesh pattern, and the adhesive layer is provided to satisfy T≥H, where H is the thickness of the metal mesh layer and T is the thickness of the thickest portion of the adhesive layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave shielding filter used for an image display device (display), and an image display device using the same.

  Since an image display device such as a plasma display uses plasma discharge for light emission, unnecessary electromagnetic waves in the 30 MHz to 1 GHz band leak outside and affect other devices (for example, remote control devices, information processing devices, etc.). There is a risk of giving. Therefore, a film-like electromagnetic wave shielding filter is provided on the front side (observer side) of the display panel used in the image display device, while maintaining the transparency of the image light and shielding (shielding) the leaked electromagnetic waves. It is common. For example, in an electromagnetic wave shielding filter for a plasma display panel, a mesh-like pattern is often used as a metal pattern that achieves both electromagnetic wave shielding performance and light transmittance. A metal pattern (EMI mesh) can be formed by bonding a metal foil to a transparent substrate with a transparent adhesive and then chemically etching the metal foil into a mesh shape by a photolithography method (Patent Documents 1 and 2). ).

  In general, the electromagnetic wave shielding filter formed of the metal pattern is combined with another optical filter and bonded to the front surface of the image display device. In general, the metal mesh and the other optical filter are laminated via an adhesive or the like. However, since the surface of the metal mesh has a concavo-convex shape, bubbles may be mixed into the recess when applying the adhesive on the surface. The bubbles scatter image light, causing the image to become cloudy, and lower the image quality such as lowering the contrast of the image and blurring the outline of the image edge. Therefore, after forming the pressure-sensitive adhesive layer, it is necessary to add another process such as an autoclave, and to remove bubbles by heating and pressurizing in that process. As a result, the electromagnetic wave shielding member cannot be continuously produced, and improvement in production efficiency has been demanded.

  Further, as the metal mesh material, the above Patent Documents 1 and 2 disclose that various conductive metal materials can be used. In particular, Patent Document 2 discloses high conductivity such as aluminum in addition to copper. Metals are also illustrated. Aluminum is an inexpensive metal material compared to copper and the like, and an alternative from copper to aluminum is desired as a metal mesh material.

  However, in practice, an electromagnetic wave shielding filter using a metal mesh made of aluminum has not been put into practical use. The reason is that there is no problem when the line width and thickness dimensions of the mesh pattern are about 100 μm or more. However, when the mesh pattern is miniaturized for a high-quality image display device, the line width and thickness dimensions are particularly large. This is because the following problems become apparent when the thickness is about 10 to 20 μm or less.

  That is, (a) aluminum itself has high activity, and an aluminum oxide film exists on the surface, which becomes a corrosion-resistant film and inhibits chemical etching. (B) When a portion of the oxide film in the region in contact with the etching solution is removed, the removed portion is rapidly etched with respect to the portion that has not yet been removed, and uniform and stable etching is difficult. is there. (C) As a result of the above (a) and (b), the contour of the line portion of the metal pattern has a zigzag shape. In other words, aluminum is inferior in the pattern accuracy of the line compared to the case of copper foil.

  Therefore, when aluminum is used, a fine pattern (for example, a line width of 10 to 20 μm and a pattern thickness of about 10 to 20 μm) required for an image display device cannot be obtained as compared with copper. Then, the unevenness leads to unevenness in the area ratio of the opening that realizes light transmittance, leading to unevenness in the surface of the display screen, and disconnection leads to deterioration in electromagnetic wave shielding performance.

JP 2003-318596 A Japanese Patent No. 3388682

  The inventors of the present invention pay attention to the relationship between the thickness of the metal mesh layer and the thickness of the pressure-sensitive adhesive layer, and make each layer a predetermined thickness. It has been found that an electromagnetic wave shielding filter having good performance and excellent production efficiency can be realized. The present invention is based on this finding.

  Therefore, an object of the present invention is to provide an electromagnetic wave shielding filter that has no bubbles remaining, has good adhesion to other optical filters, and is excellent in production efficiency.

  Another object of the present invention is to eliminate the pattern accuracy defect of an aluminum pattern formed by chemical etching, which occurs when the material of the metal pattern is changed from copper to inexpensive aluminum, and is inexpensive and practical using aluminum. An electromagnetic wave shielding filter is provided.

  Still another object of the present invention is to provide a multifunction filter using the electromagnetic wave shielding filter and an image display device using these filters.

An electromagnetic wave shielding filter according to the present invention includes a transparent substrate, a metal mesh layer provided on the transparent substrate, and an adhesive layer provided on the metal mesh layer so as to fill the irregularities of the mesh pattern. An electromagnetic shielding filter,
When the thickness of the metal mesh layer is H and the thickness of the thickest portion of the pressure-sensitive adhesive layer is T, the pressure-sensitive adhesive layer is provided so as to satisfy T ≧ H.

  In a preferred embodiment of the present invention, a metal oxide film having a thickness of 0 to 13 mm is formed on at least one surface of the metal mesh.

  Furthermore, in a preferred embodiment of the present invention, the metal is aluminum and the metal oxide is aluminum oxide.

  Moreover, in the aspect of this invention, it is preferable that the said transparent base material and the said metal mesh layer are laminated | stacked through the adhesive bond layer.

  As another aspect of the present invention, there is also provided a multifunction filter in which an electromagnetic wave shielding filter and an optical filter are laminated, and an image display device in which the electromagnetic wave shielding filter or the multifunction filter is disposed on the front surface.

  According to the electromagnetic wave shielding filter of the present invention, the thickness of the metal mesh layer and the thickness of the thickest part of the pressure-sensitive adhesive layer satisfy the relationship of T ≧ H, that is, the thickness of the thickest part of the pressure-sensitive adhesive layer is Since the pressure-sensitive adhesive layer is provided so as to be thicker than the thickness of the metal mesh layer, even if bubbles are mixed when the pressure-sensitive adhesive layer is provided on the metal mesh layer, the pressure-sensitive adhesive layer dissolves the bubbles or Since it decomposes, no bubbles remain. As a result, it is not necessary to remove residual bubbles by heating and pressurizing with an autoclave or the like, so that the electromagnetic wave shielding filter can be continuously manufactured in the form of a long film or sheet, and the production efficiency is dramatically improved. .

  In addition, by setting the thickness of the pressure-sensitive adhesive layer within the above range, when it is combined with another optical filter via the pressure-sensitive adhesive layer to obtain a multi-functional filter, the shock absorption performance is improved. Multifunctional film can be realized. Therefore, the manufacturing cost can be reduced.

  Furthermore, by defining the thickness of the aluminum oxide film at least on the upper surface side to be thin, stable etching is possible when the aluminum pattern is formed by chemical etching, and the etching quality is improved. As a result, the pattern accuracy is improved, and as a result, variations in electromagnetic shielding (surface resistance value) and haze (cloudiness) can be avoided. As a result, an electromagnetic wave shielding filter that is inexpensive in terms of material can be put into practical use by using aluminum that is less expensive than copper. Also, in terms of manufacturing, since the aluminum oxide film can be chemically etched as it is, the removal process is unnecessary, and the manufacturing process is not complicated and the cost is increased.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a layer structure of an electromagnetic wave shielding filter according to the present invention. The metal mesh layer 2 has a metal oxide film 3 on the upper surface and the lower surface thereof, and the metal mesh layer 2 is formed on the lower surface of the oxide film 3 on the lower surface side via the transparent adhesive layer 4. Adhesive fixed to and laminated. The transparent adhesive layer 4 is formed on the entire surface of the transparent substrate 1 including the opening of the metal mesh layer 2. And the adhesive layer 7 is provided on the metal mesh layer 2 so that the unevenness | corrugation of a metal mesh pattern may be filled. This pressure-sensitive adhesive layer is provided so that the relationship between the thickness H of the metal mesh layer and the thickness T of the thickest portion of the pressure-sensitive adhesive layer satisfies T ≧ H. In the present invention, the “upper surface” means a surface (also a surface facing upward in the drawing) that is in the same direction as the side on which the metal mesh layer is formed with respect to the transparent substrate, and the “lower surface” is The surface opposite to the “upper surface” (also the surface facing downward in the drawing) shall be said.

As described above, by providing the adhesive layer (T) sufficiently thicker than the thickness (H) of the metal mesh layer 2, the amount of the adhesive flowing into the concave portion of the metal mesh layer 2 can be increased. As a result, even when bubbles are mixed into the recesses when forming the pressure-sensitive adhesive layer, the bubbles can be dissolved and / or decomposed. As a result, it is not necessary to remove residual bubbles by heating and pressurizing with an autoclave or the like, so that the electromagnetic wave shielding filter can be continuously manufactured in the form of a long film or sheet, and the production efficiency is dramatically improved. . Further, by making the thickness T of the pressure-sensitive adhesive layer larger than the thickness H of the metal mesh layer, the impact resistance of the multifunction filter in which another optical filter is attached to the electromagnetic wave shielding filter is improved. For this reason, even when the multi-function filter is incorporated in the front surface of the image display device, it is not necessary to separately provide an impact absorbing film or the like, and the cost can be reduced. In this specification, “electromagnetic wave” means an electromagnetic wave in the vicinity of the KHz to GHz band whose frequency is centered in the range of 30 MHz to 1 GHz, and does not include infrared rays, visible rays, ultraviolet rays, X-rays, and the like. Shall.
The configuration of the electromagnetic wave shielding filter according to the present invention will be described in detail below.

<Transparent substrate>
The transparent substrate 1 may be appropriately selected from known materials and thicknesses in consideration of required physical properties such as transparency in the visible region (light transmittance), heat resistance, and mechanical strength. A plate-like rigid body such as a transparent inorganic plate or a resin plate may be used. However, a flexible resin film (or sheet) is preferable in consideration of suitability for continuous processing with a roll-to-roll having excellent productivity. The roll-to-roll refers to a processing method in which the material is unwound and supplied from a winding (roll), appropriately processed, and then wound and stored in the winding.

  Examples of resins for resin films and resin plates include polyesters such as polyethylene terephthalate, polyethylene naphthalate, ethylene glycol-1,4 cyclohexanedimethanol-terephthalic acid copolymer, and ethylene glycol-terephthalic acid-isophthalic acid copolymer. Examples thereof include resins, acrylic resins such as polymethyl methacrylate, polyolefin resins such as cycloolefin polymers, cellulose resins such as triacetyl cellulose, polycarbonate resins, and polyimide resins. Among them, polyethylene terephthalate is a transparent base material whose biaxially stretched film is preferable in terms of heat resistance, mechanical strength, light transmittance, cost, and the like. Examples of the transparent inorganic material include soda glass, potassium glass, borosilicate glass, lead glass and other ceramics, quartz, and ceramics such as PLZT.

  The thickness of the transparent substrate is basically not particularly limited and is appropriately selected depending on the application. When a flexible resin film is used, it is, for example, about 12 to 500 μm, preferably about 25 to 200 μm. When a resin or transparent inorganic plate is used, the thickness is, for example, about 500 to 5000 μm.

  In addition, known additives such as an ultraviolet absorber, a colorant, a filler, a plasticizer, and an antistatic agent can be appropriately added to the resin of the transparent substrate as necessary. Further, the transparent substrate may be one obtained by subjecting the surface to a known easy adhesion treatment such as corona discharge treatment or primer treatment.

<Metal mesh layer>
The metal mesh layer is a metal foil formed in a mesh pattern, and the metal itself does not transmit light, but by using a pattern with mesh openings, electromagnetic shielding performance and light transmission can be achieved. It is a balanced layer. And in this invention, it has the metal oxide film 3 with a thickness of 0 to 13 mm on the surface of this metal mesh layer (the upper surface of the metal mesh layer in FIG. 1). Note that 1Å = 0.1 nm. This metal oxide film is preferably made of a metal oxide constituting a metal mesh. The metal constituting the metal mesh is not particularly limited, and materials used as ordinary metal mesh materials, for example, metals such as copper, iron, nickel, chromium, and aluminum can be used. When aluminum is used as the metal, as described above, the inherent problem that occurs when the line width and thickness of the metal mesh pattern is about 10 to 20 μm or less, that is, the problem when the aluminum foil is formed into an aluminum pattern by chemical etching. There is a problem of stable etching and poor pattern accuracy caused thereby. First, the problem will be described with reference to FIGS.

FIG. 2A shows a state before corrosion due to etching progresses, and FIG. 2B shows a state where corrosion due to etching progresses. 2A and 2B show a state in which the aluminum foil 54 exposed in the region where the resist pattern 52 is not formed is etched with the etching solution 51. FIG.
In the case of FIG. 2A and FIG. 2B, the aluminum foil 54 having the aluminum oxide film 3 on both the front and back surfaces of the upper and lower surfaces of the aluminum layer 53 is transparently bonded to one side of the transparent substrate 1. The adhesive layer 4 is adhesively fixed and laminated to form an aluminum foil laminate 55.

  Then, as shown in FIG. 2B, when etching proceeds, the oxide film 3 on the exposed portion of the aluminum foil 54 that contacts the etching solution 51 in the non-formed portion of the resist pattern 52 is uniformly etched on the entire exposed portion. However, the etching is partially preceded, and the aluminum layer 53 is etched from the corrosion preceding portion 56. As a result, when the etching is completed, pattern accuracy defects such as burrs and disconnections frequently occur in the lines of the aluminum pattern 2 as conceptually shown in the plan view of FIG.

  Hereinafter, the metal mesh layer which comprises an electromagnetic wave shielding filter is demonstrated to the case where aluminum is used as a metal mesh layer material as an example.

  The aluminum pattern, which is a metal mesh layer, is mainly composed of aluminum, and may be aluminum alloy in addition to aluminum pure metal. These are collectively referred to as aluminum in the present invention, but the conductivity decreases when the purity of aluminum is low. The purity is preferably higher in terms of electromagnetic wave shielding performance, and aluminum having a purity of 99.0% or more is preferable. Such an aluminum pattern using aluminum having a purity of 99.0% or more is made of a foil conforming to the aluminum foil defined in JIS H4160 (aluminum and aluminum alloy foil) and JIS H4170 (high purity aluminum foil). It can be formed by using it.

  The aluminum pattern is not formed from an aluminum foil, but an aluminum pattern formed from an aluminum vapor deposition film formed on a transparent substrate by a vapor phase growth method such as a vacuum vapor deposition method may be used.

  The thickness of the aluminum pattern may be appropriately selected from the viewpoints of electromagnetic wave shielding performance, processability, mechanical strength, and the like, specifically 1 to 100 μm, preferably 5 to 20 μm, more preferably 8 to 15 μm. If the thickness is thin, electromagnetic wave shielding performance, mechanical strength and the like are lowered, and if the thickness is thick, workability is lowered.

  As for the shape of the aluminum pattern in plan view, for example, a mesh (mesh or lattice) shape, a stripe (stripe or parallel line group) shape, or a stripe (spiral) shape, etc., is compatible with electromagnetic wave shielding performance and light transmittance. This is a known pattern. Among them, a mesh shape and a square lattice shape are typical, and in addition, examples of the lattice shape include a rectangular lattice, a rhombus lattice, a hexagonal lattice, and a triangular lattice. The mesh has a plurality of openings having these shapes, and the openings are line portions (line portions or line portions) that define the openings. The line portions are usually line-shaped with a uniform width, and usually the openings and the spaces between the openings are all the same shape and the same size.

  In addition, in the display application, the above pattern is a solid pattern that does not have an opening for grounding continuity around the four sides that do not affect the image display of the electromagnetic wave shielding filter, or grounding that has a small occupied area ratio. An area may be provided around an internal image display area having an opening.

  The line width of the line portion of the pattern is, for example, 5 to 50 μm, and the upper limit is 30 μm, particularly 20 μm, from the point that the effect of the present invention is more conspicuous. The lower limit of the line width can be adjusted as appropriate from the viewpoints of heavy electromagnetic wave shielding and mechanical strength, but is preferably 10 μm or more. The line interval (pitch), which is a line repetition period, is, for example, 100 to 500 μm. The aperture ratio (area ratio of the opening to the total area of the mesh pattern formation region) is 50 to 95%.

  In order to form the pattern of the aluminum pattern, it can be formed by chemical etching after laminating an aluminum layer such as an aluminum foil on the transparent base material before pattern formation. For pattern formation of the resist pattern during chemical etching, a known pattern formation method such as a photolithography method (pattern exposure method) or a printing method may be appropriately selected. Among these, the photolithography method is a preferable method compared to the printing method in that a highly accurate pattern such as a line width required for the electromagnetic wave shielding filter and its uniformity can be stably formed.

  A known etching solution may be appropriately selected and used as an etching solution for chemically etching the aluminum pattern. For example, an acidic etching solution containing ferric chloride. Etching is performed including an aluminum oxide film in the resist pattern non-formation portion on the upper surface of the aluminum layer. It is not particularly necessary to remove the aluminum oxide film on the upper surface as a pretreatment for etching. Then, the aluminum oxide film 3 on the upper and lower surfaces corresponding to the resist pattern forming portion remains as the oxide film 3 on the upper and lower surfaces of the aluminum pattern 2.

<Oxide film of aluminum>
The aluminum oxide film is a layer containing aluminum oxide. When an aluminum pattern is formed using an aluminum foil, the aluminum oxide film exists on both the top and bottom surfaces of the foil. When the pattern is formed, the thickness of the etched side, that is, the upper surface side is defined. The upper limit of the thickness of the aluminum oxide film on at least the upper surface of the aluminum pattern is 13 mm, preferably 12 mm, more preferably 10 mm, and even more preferably 8 mm. By setting the upper limit of the thickness of the aluminum oxide film on at least the upper surface as described above, stable chemical etching is possible even if the oxide film remains present, and a line generated when an aluminum layer is used. It is possible to prevent jaggedness and disconnection of the part outline, and to avoid pattern accuracy defects caused by changing copper to inexpensive aluminum.

  By the way, normally manufactured aluminum foil is manufactured by a rolling method, and manufactured and stored at normal temperature (20 ° C., around 50% RH), such as aluminum ingot rolling process, foil manufacturing process through annealing process, and subsequent storage in air. By doing so, an active aluminum irreversibly forms an oxide film of aluminum on the surface. However, it does not become a thin oxide film as in the present invention, but is thicker than 15 mm, usually about 20 to 100 mm. It becomes an oxide film.

  Further, the lower limit of the thickness of the aluminum oxide film on the upper surface of the aluminum pattern is 0 (zero), that is, no oxide film may be present from the viewpoint of not inhibiting chemical etching. However, the oxide film of aluminum is said to be a passive film, and during the process of processing, transporting and storing the aluminum foil, oxidation or corrosion (inadvertently or undesired) proceeds inside the aluminum foil. In this respect, an oxide film as a dense aluminum passivating film having a thickness of about 2 to 3 mm may be formed.

  For aluminum patterns that do not have an aluminum oxide film on the upper surface, the aluminum layer before pattern formation is formed on a transparent substrate in vacuum and in an inert gas, and the upper surface of the aluminum layer is coated with a resin before forming the oxide film. This can be achieved by blocking the oxidation reaction. Thereafter, if a predetermined pattern is formed by chemical etching, an aluminum pattern having no aluminum oxide film on the upper surface is obtained.

  There are various ways to reduce the thickness of the aluminum oxide film as described above, but when aluminum foil is used for the aluminum pattern, the aluminum foil is made by rolling, and then manufactured by annealing. However, it can adjust to the target thickness by adjusting rolling conditions and annealing conditions.

  For example, when removing the rolling oil adhering to the surface of the aluminum foil after rolling during annealing, the gas composition of the annealing atmosphere is controlled so that the surface is not oxidized (the oxygen concentration is lowered), aluminum There are methods such as removing the aluminum oxide film on the foil surface with chemicals. Although there is a method of not annealing, rolling oil is not preferable because it adversely affects the photolithography method.

  The thickness of the aluminum oxide film can be measured by X-ray photoelectron spectroscopy (XPS), which is a kind of Hunter Hall method and X-ray fluorescence analysis.

  The aluminum oxide film is usually formed on both the front and back surfaces of the foil, that is, both the upper surface and the lower surface, from the foil manufacturing process. Among these, since it is the oxide film on the upper surface that affects the chemical etching for pattern formation of the aluminum pattern, the present invention defines a specific thickness (thinness) for at least the aluminum oxide film on the upper surface. Note that the aluminum oxide film on the bottom surface does not need to be specified in terms of pattern accuracy because the contribution to the generation of mesh-shaped burrs during chemical etching is usually negligible compared to the aluminum oxide film on the top surface. . However, if the film thickness is too thick, an adverse effect on the mesh shape due to the aluminum oxide film remaining in the opening may occur, and the transparency of the opening may be reduced. For this reason, it is recommended that the aluminum oxide film on the lower surface is preferably less than the minimum visible light wavelength of 380 nm, more preferably 200 nm or less. For example, the film thickness of the aluminum oxide film on the lower surface is set to 0 to 13 mm similarly to the upper surface. As an embodiment of the present invention, by adjusting the thickness of the aluminum oxide film on the lower surface before chemical etching and the processing conditions for chemical etching, the pattern opening has a minimum wavelength of visible light of less than 380 nm (for example, 3 to 13 mm). A transparent aluminum oxide film having a thickness of) is left, and the transparent adhesive layer or the transparent substrate exposed to the opening during chemical etching can be protected from coloring by the corrosive liquid.

  However, if the lower surface aluminum oxide film has the same thickness as that of the upper surface oxide film, the thickness of the lower surface aluminum oxide film is defined to be the same as the thickness of the upper surface aluminum oxide film. be able to.

<Blackening layer>
The aluminum pattern may have a blackened layer on the surface. The blackening treatment layer is a layer for improving external light absorption and image contrast by suppressing light reflection by the aluminum pattern and the oxide film on the surface. The blackening treatment layer is provided when external light absorption and image contrast improvement are required. When there is an oxide film on the surface or surface of the aluminum pattern, the blackening treatment layer is a layer that is provided on the surface of the film to reduce the light reflectance.

  Here, the surface refers to a surface such as an upper surface, a lower surface, or a side surface. The surface on which the blackening treatment is performed to form the blackening treatment layer may be surfaces according to demand, such as the upper surface only, the upper surface and both side surfaces, the lower surface only, the upper surface, both side surfaces, and the entire lower surface. This is the same as a known blackening process. Among these, the surface in contact with the transparent adhesive in the presence of the transparent adhesive layer is the lower surface. Further, in order to use the electromagnetic wave shielding filter with the upper surface side of the observer side, it is preferable to form a blackening treatment layer on at least the upper surface, more preferably on both side surfaces, and on the lower surface on the image display element side described later. Also, a blackening treatment layer is preferably formed.

  As the blackening treatment layer, any known electromagnetic shielding filter may be adopted as appropriate. For example, as the blackening treatment layer, an inorganic material such as a metal, an organic material such as a black resin, or the like can be used. The inorganic material is, for example, a metal compound such as a metal or an alloy, a metal oxide, or a metal sulfide, and can be formed by a known blackening process such as a plating method. Moreover, as black resin, it can form as a layer which contained the black coloring agent in resin, for example.

<Adhesive layer>
The pressure-sensitive adhesive layer 7 has a function of bonding the electromagnetic wave shielding filter to another optical member, and also has a function of filling the unevenness of the conductive pattern layer and flattening, and an impact resistance (impact absorption) function. The thickness of the pressure-sensitive adhesive layer is formed so that the thickest portion of the layer, that is, the opening portion in FIG. 1 is 40 μm or more. As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, acrylic resin, vinyl chloride-vinyl acetate copolymer, thermoplastic polyester resin, rubber and the like can be used. In addition, thermosetting resins and ionizing radiation curable resins can also be used.

  In addition, the pressure-sensitive adhesive layer has a near-infrared absorbing agent, an ultraviolet absorbing agent, a neon light absorbing agent, various coloring pigments, an antistatic agent, etc. for correcting the color tone of the display device or absorbing near infrared rays. Can be contained.

  The pressure-sensitive adhesive layer is formed by directly applying a fluid pressure-sensitive adhesive so as to fill the irregularities of the conductive pattern layer. Alternatively, a transfer sheet in which a pressure-sensitive adhesive layer is previously formed on a release substrate is prepared, the pressure-sensitive adhesive layer surface of the transfer sheet is adhered onto the conductive pattern layer, and then the release substrate is peeled off. The pressure-sensitive adhesive layer may be formed using a method. The fluidity is not limited to Newtonian viscosity, but may be dilatancy or thixotropic non-Newtonian viscosity. The viscosity may be a viscosity sufficient to fill the unevenness of the conductive pattern layer, and is appropriately adjusted according to the processing conditions and the degree of unevenness during coating or transfer (when the pressure-sensitive adhesive layer is formed by transfer).

  As a method for applying the pressure-sensitive adhesive, roll coating, gravure roll coating, bar coating, curtain flow coating, die coating, comma coating, spray coating, and the like can be suitably employed.

  Also, when forming the pressure-sensitive adhesive layer, if the pressure-sensitive adhesive layer formed on the conductive pattern layer has fluidity at that time, it remains in that state, and the pressure-sensitive adhesive layer has little fluidity at that time , The pressure-sensitive adhesive layer is heated and fluidized by a method such as softening or melting. Next, the fluid pressure-sensitive adhesive layer is filled in the irregularities of the conductive pattern layer, and is replaced with the air in the irregularities. During this process, the side opposite to the conductive pattern side of the adhesive layer is the flat surface of the release substrate of the transfer sheet in the case of the transfer method, and a separately prepared mirror in the case of the direct coating method. A flat surface such as a face plate is brought into contact with and pressed to regulate deformation of the adhesive layer.

The release substrate used for the transfer sheet is not particularly limited, but has dimensional stability (elastic modulus) against moderate strength and stress, heat resistance (especially when overheating during transfer), and surface smoothness. It is preferable to select one having a high value. Further, in order to ensure releasability (also referred to as releasability) from the transfer layer, it is preferable to form a release layer on the transfer layer side. For example, a resin sheet having a thickness of about 20 to 100 μm or paper having a basis weight of 20 to 100 g / m ² is used. Examples of the resin sheet include polyester resin sheets such as polyethylene terephthalate and polyethylene naphthalate, and polyolefin resin sheets such as polypropylene and polymethylpentene. As the paper, high quality paper, parchment paper, glassine paper, sulfuric acid paper or the like that is as uniform as possible is used.

  The release layer is formed when the release substrate itself has insufficient peelability from the transfer layer. For the release layer, a material having high adhesion to the base sheet and high releasability from the transfer layer is selected. As a material for the release layer, melamine resin, silicon resin, polyolefin resin, or the like is used. If necessary, a release agent made of wax, fluororesin or the like is added thereto. The thickness of the release layer is usually about 0.1 to 5 μm.

<Transparent adhesive layer>
The transparent adhesive layer 4 is a layer for fixing the aluminum pattern to the transparent substrate. For example, when the aluminum pattern is formed from an aluminum foil, the transparent adhesive layer 4 is used for bonding and fixing the aluminum foil to the transparent substrate. . In addition, a transparent adhesive bond layer can be abbreviate | omitted when forming from the aluminum layer which laminated | stacked the aluminum pattern directly on the transparent base material by aluminum vapor deposition.

  The transparent adhesive layer may be a transparent adhesive so as not to impair the light transmission through the openings of the aluminum pattern, and a known transparent adhesive may be used as appropriate. For example, urethane adhesive, acrylic adhesive, epoxy adhesive, rubber adhesive, and the like. Among these, urethane adhesives, for example, two-component curable urethane adhesives are preferable in terms of adhesive strength. As the two-component curable urethane-based adhesive, an adhesive using a polyol as a main agent and a polyisocyanate compound as a curing agent can be used. Examples of the polyol include acrylic polyol, polyester polyol, polyurethane polyol, polyether polyol, and polyester polyurethane polyol. Examples of the polyisocyanate compound include tolylene diisocyanate, xylylene diisocyanate, and hexamethylene diisocyanate. A plurality of polyols and polyisocyanates may be used.

  The transparent adhesive layer can be formed by applying a transparent adhesive to one or both of an aluminum foil and a transparent substrate by a known forming method, and then laminating them through the adhesive. Examples of the forming method include the coating method and the printing method described above.

<Multi-function filter>
FIG. 4 is a cross-sectional view showing one embodiment of the multifunction filter. The multi-function filter 20 is a filter having an optical filter function as well as an electromagnetic wave shielding function by further laminating an optical filter on the above-described electromagnetic wave shielding filter. FIG. 4 is a cross-sectional view showing one embodiment of such a multifunction filter 20, which is a filter having a configuration in which the optical filter 5 is directly laminated on one surface of the electromagnetic wave shielding filter 10.

  The laminated surface may be either one or both sides of the electromagnetic wave shielding filter 10, but when the laminated surface is a single side, a so-called direct-attached multifunction filter is provided by providing it on the surface on the upper surface side of the adhesive layer. Can do. In this case, since the pressure-sensitive adhesive layer has a predetermined thickness as described above, it can also have impact resistance.

  By making a multi-function filter in which an optical filter is further laminated on an electromagnetic wave shielding filter, the multi-functionality is provided with an optical filter function as well as an electromagnetic wave shielding function, making it possible to share a transparent base material and reduce the thickness of the filter. Cost reduction is also possible.

<Optical filter>
As the optical filter 5, a known optical filter having an optical filter function may be appropriately selected. Optical filter functions include, for example, a near-infrared absorption function that absorbs near-infrared light, an ultraviolet absorption function that absorbs ultraviolet light, a neon light absorption function that absorbs neon light from a plasma display, and color correction that corrects the display image to a desired color tone. A thin film having a specific light transmission function such as a function, an antireflection function (any of antiglare, antireflection, antiglare and antireflection), or a contrast enhancement function by antireflection of external light described in JP-A-2007-272161 It is a minute louver.

  The optical filter 5 has one function or two or more functions among various optical filter functions such as the above-described near-infrared absorption function, antireflection function, and contrast enhancement function.

  These various optical filter functions, for example, near infrared absorption function, neon light absorption function, color correction function, etc., using dyes corresponding to these functions (near infrared absorption dye, neon light absorption dye, color correction dye), The ultraviolet absorbing function can be realized by a known material / method such as using an ultraviolet absorber. For example, a resin layer in which these materials are dispersed in a resin can be formed as an optical filter layer by a known coating method, extrusion method, or the like. In addition, the resin layer can be used for a plurality of functions depending on a single layer or a multilayer structure.

  Further, the optical filter layer having an optical filter function including an antireflection function may be appropriately laminated on a transparent substrate to form an optical filter. In addition, as a transparent base material here, the material listed with the transparent base material of the above-mentioned electromagnetic wave shielding filter can be used.

<Other layers>
The electromagnetic wave shielding filter and the multi-function filter described above include other layers such as a flattening resin layer for flattening the unevenness on the upper surface side of the aluminum pattern, a surface protective layer for protecting the surface, a hard coat layer, and a contamination prevention function. In these filters, known layers such as a layer, an antistatic functional layer, and an adhesive layer can be laminated. These layers can be combined.

<Image display device>
The image display device of the present invention is an image display device in which the above-described electromagnetic wave shielding filter or multi-functional filter is disposed on the front surface, and more specifically, the above-described electromagnetic wave shielding filter or multi-functional filter is disposed on the observer side of the image display element. It is the display device arranged in. The front surface is the observer side of the image display device. Moreover, arrangement | positioning should just follow a well-known form.

  By using such an image display device, the cost can be reduced, and the spread of the image display device can be promoted.

  Examples of image display elements include plasma display panels (also referred to as PDPs), cathode ray tubes (also referred to as CRTs), liquid crystal display elements (also referred to as LCDs), electroluminescent elements (also referred to as ELs), and display elements that generate electromagnetic waves. is there. For example, in PDP, unnecessary electromagnetic waves in a band of 30 MHz to 1 GHz are generated.

  The arrangement form in which the electromagnetic wave shielding filter or the multi-function filter is arranged on the observer side of the image display element is roughly divided into the electromagnetic wave shielding filter or the multi-function filter on the observer side surface of the image display element without a space, However, usually, a configuration in which layers are directly laminated via an adhesive layer (FIG. 5A), and a configuration in which an electromagnetic wave shielding filter or a multifunction filter is disposed on the observer side of the image display element through a space [ FIG. 5 (b)].

  The image display device 40 in the form of being directly laminated as shown in FIG. 5A directly connects the electromagnetic wave shielding filter 10 or the multi-function filter 20 without leaving a gap on the surface of the image display element 30 on the viewer side. It is a laminated display device. The electromagnetic wave shielding filter 10 or the multifunction filter 20 can be obtained by directly pasting the image display element 30 on the surface on the viewer side. In that case, it laminates | stacks through a transparent adhesive agent as needed. The adhesive (including the pressure-sensitive adhesive) may be a known one such as an adhesive layer provided as a part of the electromagnetic wave shielding filter 10 or the multi-function filter 20, or an adhesive layer applied between the layers. As the transparent adhesive, the adhesive listed in the transparent adhesive layer described above can be used.

  On the other hand, in the case of the image display device 40 arranged in a space shown in FIG. 5B, a plate-like laminate in which the electromagnetic wave shielding filter 10 or the multifunction filter 20 is once laminated directly on the surface of the transparent substrate 6. 21 is arranged with a space on the viewer side of the image display element 20.

  As shown in FIG. 5B, in the form in which the electromagnetic wave shielding filter 10 or the multi-function filter 20 is disposed with a space therebetween, the electromagnetic wave shielding filter 10 or the multi-function filter 20 is not a rigid plate-like body but a sheet or When the film shape is flexible and the shape cannot be maintained, the plate-like laminate 21 laminated with the transparent substrate 6 is preferable in that the shape can be maintained. Further, in the plate-like laminate 21, in the form illustrated in FIG. 5B, the electromagnetic wave shielding filter 10 or the multifunction filter 20 is laminated on the surface on the viewer side with respect to the transparent substrate 6. Further, it may be laminated on the surface on the image display element side.

<Transparent substrate>
As the transparent substrate 6 interposed between the electromagnetic wave shielding filter 10 or the multifunction filter 20 and the image display element 30, a plate-like body capable of maintaining the shape, for example, an inorganic plate such as glass or ceramic, a resin plate, or the like is used. it can. Examples of the resin for the resin plate include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acrylic resins such as polymethyl methacrylate, polyolefin resins such as cycloolefin polymers, cellulose resins such as triacetyl cellulose, and polycarbonate. Resin, polyimide resin and the like. In the resin of the transparent substrate, known additives such as an ultraviolet absorber, a colorant, a filler, a plasticizer, and an antistatic agent can be appropriately added as necessary.

  The electromagnetic wave shielding filter according to the present invention is suitably used as a front filter of an image display device, but it goes without saying that it can be applied to other applications. For example, in windows where buildings such as houses, offices, stores, hospitals, schools, etc., windows of various household appliances such as microwave ovens, and windows of vehicles such as vehicles, ships, aircrafts, etc. where light transmission is required It can also be used for electromagnetic shielding applications.

  The electromagnetic wave shielding filter according to the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Production Example 1
First, a continuous strip-shaped rolled aluminum foil having a thickness of 12 μm was prepared as a metal foil for an aluminum pattern. When the thickness of the oxide film on the surface of this aluminum foil was measured, it was 8 mm on both the upper and lower surfaces. Further, as a transparent substrate, a continuous belt-like uncolored transparent biaxially stretched polyethylene terephthalate film having a polyester resin primer layer formed on one side was prepared.

  Next, the primer layer surface of the transparent substrate and the glossy surface of the aluminum foil are cured with respect to 12 parts by mass of a transparent two-component curable urethane resin-based adhesive (polyester polyurethane polyol having an average molecular weight of 30,000 as a main component). (Including 1 part by mass of xylylene diisocyanate-based prepolymer as an agent) and then cured at 50 ° C. for 3 days to form a continuous strip of aluminum having a 7 μm thick transparent adhesive layer between the aluminum foil and the transparent substrate. A foil laminated sheet was obtained.

  Next, the aluminum foil of the aluminum foil laminated sheet is subjected to a chemical etching process using a photolithography method to form a mesh-like region composed of an opening and a line portion, and a frame shape on the outer edge surrounding the mesh-like region. An aluminum pattern having a grounding region with no opening was formed.

  Specifically, the etching was consistently performed from masking to etching on the continuous belt-like laminated sheet using a production line for a color TV shadow mask. That is, after applying a photosensitive etching resist on the entire surface of the aluminum foil of the laminated sheet, a desired mesh pattern is closely exposed, developed, hardened, and baked to form a resist on the area corresponding to the mesh opening. After forming the resist pattern in which the layer is not formed, the aluminum foil in the resist layer non-formed part is removed by etching with an acid aqueous etchant containing ferric chloride to have a mesh-like opening. An aluminum pattern was formed, and then washing with water, stripping of the resist, washing, and drying were sequentially performed.

  The mesh shape of the mesh area (image display area) is such that the line width of the linear line portion whose opening is a square and non-opening is 20 μm, the line interval (pitch) is 300 μm, and the height of the line portion. When cut into a rectangular sheet of 12 μm, the bias angle defined as the minor angle formed by the line portion and the long side of the rectangle was 49 degrees.

  Thus, the intermediate body of the electromagnetic wave shielding filter of width dimension 605mm was obtained, and it wound up in roll shape. The obtained roll-shaped electromagnetic shielding filter intermediate is continuously supplied to the blackening device using rolls, tows, and rolls, and a nickel compound blackening layer is formed on the aluminum pattern surface of the intermediate. did.

  Subsequently, an adhesive layer was provided on the aluminum mesh surface on which the blackening treatment layer was formed so as to fill the irregularities of the mesh pattern. First, a 25 μm, 40 μm, and 50 μm thick adhesive layer (product name: TD06A, manufactured by Yodogawa Paper Mill) formed on a release film made of PET film is fixed between a rubber roll and a metal roll, each fixed with a certain gap. Then, an electromagnetic wave shielding filter was obtained by pressing and pasting onto the aluminum mesh pattern layer obtained above.

<Evaluation of filling degree of adhesive layer>
About the obtained electromagnetic wave shielding filter, embedding evaluation of the adhesive layer was performed. The light of the fluorescent lamp was observed through an electromagnetic wave shielding filter, and the transparency of the electromagnetic wave shielding filter was visually evaluated. Further, arbitrary three rows each in the vertical and horizontal directions of the mesh pattern of the A4 size electromagnetic wave shielding filter were observed with a microscope (100 times magnification).
The results were as shown in Table 1 below.

  As shown in Table 1, in the visual evaluation, the electromagnetic wave shielding filter having a pressure-sensitive adhesive layer thickness of 10 μm that does not satisfy T ≧ H appeared to be clouded and the transmitted light was blurred, whereas the thickness was 50 μm. The entire surface of the electromagnetic wave shielding filter using the pressure-sensitive adhesive layer was transparent (in the comprehensive evaluation, this state was indicated as ◯). Further, as a result of microscopic observation, the presence of bubbles could not be confirmed, and the adhesive was uniformly filled (in the comprehensive evaluation, this state is indicated as “◯”).

  Further, the electromagnetic wave shielding filter using the adhesive layer having a thickness of 25 or 40 μm has a part of cloudiness in visual evaluation (this state is expressed as Δ), and in microscopic observation, along the mesh pattern lattice. Although air bubbles seemed to be unfilled parts were found, all were judged to be practically acceptable (this state is expressed as Δ).

  On the other hand, in the electromagnetic wave shielding filter using the 10 μm thick adhesive layer, white turbidity is recognized on the entire surface in visual evaluation (this state is expressed as “X”), and bubbles are distributed on the entire surface in microscopic observation, and The unfilled part of the adhesive was continuously distributed along the line part (this state is expressed as “x”), and it was determined that it was practically unacceptable.

Production Example 2
An electromagnetic wave shielding filter was obtained in the same manner as in Production Example 1 except that an electromagnetic wave shielding filter having a pressure-sensitive adhesive layer thickness of 50 μm was used with a surface oxide film of aluminum foil having a thickness of 15 mm.
As for the pattern accuracy of the aluminum pattern of the electromagnetic wave shielding filter of Production Example 1, the variation in the mesh line width was 4.5 μm, the surface unevenness had no problem in appearance, and there was almost no variation in the surface resistance value. On the other hand, in the electromagnetic wave shielding filter of Production Example 2, breakage occurred frequently in the mesh lines (line width variation of 20 μm or more), surface unevenness was conspicuous visually, and the surface resistance value varied greatly.

Sectional drawing which shows one form of the electromagnetic wave shielding filter by this invention. Sectional drawing explaining the cause which a pattern precision defect produces at the time of etching an aluminum pattern. The top view which illustrates the pattern accuracy defect of an aluminum pattern notionally. Sectional drawing which shows one form of the multifunction filter by this invention. Sectional drawing which shows the example of a form of the image display apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base material 2 Aluminum pattern 3 Oxide film 4 Transparent adhesive layer 5 Optical filter 6 Transparent substrate 7 Adhesive layer 10 Electromagnetic wave shielding filter 20 Multifunctional filter 21 Plate-shaped laminated body 30 Image display element 40 Image display apparatus 51 Etching liquid 52 Resist pattern 53 Aluminum layer 54 Aluminum foil 55 Aluminum foil laminate (sheet)
56 Corrosion preceding part

Claims (6)

An electromagnetic wave shielding filter comprising a transparent substrate, a metal mesh layer provided on the transparent substrate, and an adhesive layer provided on the metal mesh layer so as to fill the irregularities of the mesh pattern,
An electromagnetic wave shielding filter, wherein the pressure-sensitive adhesive layer is provided so as to satisfy T ≧ H, where H is the thickness of the metal mesh layer and T is the thickness of the thickest portion of the pressure-sensitive adhesive layer. .   The electromagnetic wave shielding filter according to claim 1, wherein a metal oxide film having a thickness of 0 to 13 mm is formed on at least one surface of the metal mesh. The electromagnetic wave shielding filter according to claim 1 or 2, wherein the metal is aluminum and the metal oxide is aluminum oxide.   The electromagnetic wave shielding filter according to any one of claims 1 to 3, wherein the transparent base material and the metal mesh layer are laminated via an adhesive layer.   The multifunction filter which laminated | stacked the electromagnetic wave shielding filter as described in any one of Claims 1-4, and the optical filter.   The image display apparatus which has arrange | positioned the electromagnetic wave shielding filter as described in any one of Claims 1-4, or the multifunction filter of Claim 5 in the front surface.

Images