JPWO2007037329A1 - Electromagnetic shield filter - Google Patents

Abstract

The main object of the present invention is to provide an electromagnetic wave shielding filter having a blackening treatment surface that has a sufficient degree of blackening and has an excellent antireflection effect even when used in a configuration that exhibits a wet color. To do. In the electromagnetic wave shielding filter having at least a conductive mesh layer on a transparent substrate, the present invention is such that at least one of the front and back surfaces of the conductive mesh layer is blackened, The total light reflectance (RSCI) measured in accordance with JIS Z8722 is 12% or less, and the ratio (RSCE / RSCI) of diffused light reflectance (RSCE) to total light reflectance (RSCI) is 0.8 or more. The above-described problems have been solved by an electromagnetic wave shielding filter that is characterized.

Description

  The present invention relates to an electromagnetic wave shielding filter having optical transparency that shields (shields) electromagnetic waves generated from a display such as a CRT or a PDP.

  In recent years, with the advancement of functions and increased use of electrical and electronic equipment, electromagnetic noise interference (EMI) has increased, and electromagnetic waves are also generated in displays such as cathode ray tubes (referred to as CRT) and plasma display panels (referred to as PDP). appear. In order to shield this electromagnetic wave, an electromagnetic wave shielding filter disposed on the front surface of the display is known. In the electromagnetic wave shielding filter used for such an application, light transmittance is required in addition to the electromagnetic wave shielding performance. Therefore, there is known an electromagnetic wave shielding shield filter in which a transparent substrate such as a resin film or a glass plate is used as a substrate, and a conductive mesh layer is formed on the transparent substrate by etching a metal foil or metal plating. It has been.

  As described above, when the mesh layer is formed using a copper foil, a copper plating layer, etc., unnecessary light such as external light is reflected by the mesh layer, and the reflected metallic luster reduces the bright room contrast of the fluoroscopic image. . Therefore, normally, the mesh layer has a blackened surface that has a black appearance, such as a structure in which the surface is covered with a blackened layer to prevent light reflection (Patent Documents 1 and 2). . At that time, it is said that the surface roughness should be regulated in that the blackened surface has a high degree of blackening and improved light reflection prevention performance. For example, Patent Document 1 defines a surface roughness Ra of 0.10 to 1.00 μm. In Patent Document 2, the arithmetic average roughness Ra defined in JIS B0601 is specified in a range of 0.02 to 1.00 μm.

JP 2000-286594 A JP 2003-318596 A

The electromagnetic shielding filter rarely has a structure in which the mesh layer is directly exposed to the air. Usually, a transparent resin layer is provided so as to cover the mesh layer in order to protect the mesh layer and add an optical filter function. There are many cases. For this reason, the blackened surface on the transparent resin layer side of the mesh layer is in a state in which the transparent resin layer is closely adhered and wetted by the transparent resin layer. For this reason, the blackened surface has an appearance different from that when exposed to air (this is referred to as “wet color” after the surface is wetted with liquid). The phenomenon of appearing wet color is the same even in a configuration in which a mesh layer having the transparent substrate side as a blackened surface is laminated on the transparent substrate.
Therefore, in the configuration that is normally used, the appearance of the blackened surface is directly affected by the wet color. If the arithmetic surface roughness Ra is defined as in the prior art, the blackened surface is blackened. In some cases, the degree of conversion could not be sufficiently obtained.

  The present invention has been made to solve the above problems, and even when used in a configuration exhibiting a wet color, the blackening treatment surface has a sufficient degree of blackening and has an excellent antireflection effect. It aims at providing the electromagnetic wave shielding filter which has this.

In order to solve the above problems, an electromagnetic wave shielding filter according to the present invention is an electromagnetic wave shielding filter having at least a conductive mesh layer on a transparent substrate, and at least one surface of at least front and back surfaces of the conductive mesh layer. Is blackened, the total light reflectance (R _SCI ) measured according to JIS Z8722 of the blackened surface is 14% or less, and the diffused light reflectance (R _SCI ) relative to the total light reflectance (R _SCI ) _SCE ) ratio ( _RSCE / _RSCI ) is 0.8 or more.
The electromagnetic wave shielding filter according to the present invention wets the blackened surface of the blackened conductive mesh layer by setting the total reflectance and the ratio of the diffuse reflectance to the total reflectance within the specific range. Even when it is used in a configuration that exhibits color, it can have a blackening treatment surface with sufficient blackening degree and excellent anti-reflection effect, and improve the visibility of the image on the display Can do.

  In the electromagnetic wave shielding filter according to the present invention, when the blackened surface has minute irregularities, and a roughness curve is adopted as the contour curve of the minute irregularities, the ten-point average roughness RzJIS ( Since JIS B0601 (1994 edition) is 2 μm or more, it can have a blackening treatment surface with a sufficient blackening degree and an excellent antireflection effect, and can improve visibility. It is mentioned as a preferred embodiment.

  The electromagnetic wave shielding filter according to the present invention may have a configuration in which a transparent resin layer is laminated on the blackened surface of the conductive mesh layer having the blackened surface. In the case of such a configuration, the blackened surface under the transparent resin layer can be protected from corrosion and scratches by the transparent resin layer. Furthermore, the blackened surface of the mesh layer under the transparent resin layer becomes a wet color when in contact with the transparent resin layer. This is because it is excellent in terms.

  The electromagnetic wave shielding filter according to the present invention wets the blackened surface of the blackened conductive mesh layer by setting the total reflectance and the ratio of the diffuse reflectance to the total reflectance within the specific range. Even when it is used in a configuration exhibiting a color, it can have a blackening treatment surface with a sufficient blackening degree and an excellent antireflection effect. As a result, according to the electromagnetic wave shielding filter according to the present invention, the reflection of light is reduced, and the visibility of the image on the display can be improved by giving a sense of contrast.

It is sectional drawing which shows the example of the electromagnetic wave shield filter which concerns on this invention. It is sectional drawing which shows the example of a combination of the blackening process surface in the mesh layer of the electromagnetic wave shield filter which concerns on this invention. (A) is a contour curve (roughness curve R), (B) is a probability density function ADF and a load curve BAC, and (C) is a graph obtained by rotating (B) so that the probability density is positive on the vertical axis. FIG. An example of an upward convex curve shape suitable for the present invention is (A) and a downward convex curve shape example is (B), which shows a (probability density) curve adc obtained by smoothing the probability density function ADF.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base material 2 Mesh layer 21 Mesh-like conductor layer 22 Blackening layer 3 Transparent resin layer 4 Adhering body 10 Electromagnetic wave shielding filter ADF Probability density function Adc Probability density curve BAC Load curve ML Average line R Roughness curve Rp (Coarse Maximum peak height (of roughness curve) Rv Maximum valley depth (of roughness curve)

In order to solve the above problems, an electromagnetic wave shielding filter according to the present invention is an electromagnetic wave shielding filter having at least a conductive mesh layer on a transparent substrate, and at least one surface of at least front and back surfaces of the conductive mesh layer. Is blackened, the total light reflectance (R _SCI ) measured according to JIS Z8722 of the blackened surface is 14% or less, and the diffused light reflectance (R _SCI ) relative to the total light reflectance (R _SCI ) _SCE ) ratio ( _RSCE / _RSCI ) is 0.8 or more.

The blackening treatment surface in the present invention is provided at least on the side where the observer views the electromagnetic wave shielding filter in the form in which the electromagnetic wave shielding filter is used for a display. Further, the total light reflectance was measured in accordance with JIS Z8722 blackening surface in the present invention _{(R SCI)} is in conformity with JIS Z8722, spectrophotometer (e.g., Konica Minolta Sensing Co., Ltd., CM -3600d) is set to the reflection mode, the light source is the standard light D65, and the field of view is 2 °, and the detector uses the total reflection light (integral of both the diffuse reflection light and the specular reflection light in the reflection light). ) The Y value (Y of the tristimulus values XYZ) is measured by setting the SCI (Special Component Include) mode to measure the intensity. The diffusion light reflectance was measured in accordance with JIS Z8722 of blackening treatment surface (R _SCE) is similarly using spectrophotometer, the light source and the field of view is the same as above, a detector, the reflected The Y value (Y of tristimulus values XYZ) is measured by setting the SCE (Special Component Exclude) mode in which the (integral) intensity of only diffuse reflected light in the light is measured.

  The electromagnetic wave shielding filter according to the present invention optimizes the blackened surface so as to have the specific reflection characteristics as described above, so that it looks black even in wet color and does not shine black, and is conductive. It is possible to prevent the black level of the fluoroscopic image from being reduced due to reflection of external light on the mesh layer surface, and to improve the black level. Therefore, when the electromagnetic wave shielding filter according to the present invention is provided, the visibility of the image on the display can be improved by providing a bright room contrast feeling of the fluoroscopic image.

〔Layer structure〕
First, FIG. 1 is a cross-sectional view illustrating a basic form of an electromagnetic wave shielding filter 10 according to the present invention.
FIG. 1A shows a configuration in which a conductive mesh layer 2 (hereinafter also simply referred to as “mesh layer”) is laminated on a transparent substrate 1. FIG. 1B shows a configuration in which a conductive mesh layer 2 is laminated on the transparent substrate 1 and a transparent resin layer 3 is further laminated on the conductive mesh layer 2. Moreover, the adherend layer 4 may be laminated on the transparent resin layer 3 as shown in FIG. 1C, or the adherend layer may be placed on the transparent substrate 1 side as shown in FIG. 4 may be laminated. In FIG. 1, the conductive mesh layer 2 includes a mesh-like conductor layer 21 and a blackened layer 22, and the blackened surface of the mesh layer is formed on the surface of the mesh-like conductor layer. 22 faces are formed. In addition, FIG. 1 is explanatory drawing in the form which formed the blackening process surface in the surface (drawing upper part) and both sides | surfaces of the filament part (line part) of the conductor mesh layer 2. FIG. The blackening treatment surface is provided on at least one of the front and back surfaces of the conductive mesh layer, and there are various combinations of treatment surfaces as will be described later with reference to FIG. The adherend layer 4 is, for example, a sheet-like, plate-like, or coating-like, various optical filters such as an antireflection filter and a near-infrared absorption filter, a protective film, or a component of the display itself. It is a layer having an arbitrary function such as a front substrate.

  In addition, as an electromagnetic wave shielding filter, you may provide another layer suitably as needed. For example, when there is a concern about the rust of the conductive mesh layer, various layers and treatments in a conventionally known electromagnetic wave shielding filter, such as coating with a rust prevention layer, are added within a range not departing from the purpose and effect of the present invention. Also good.

  Here, in the present invention, the “front side” and “surface” are the side on which the conductive mesh layer is formed with respect to the transparent substrate as “front side” (also the side facing upward in the drawing), and the conductive mesh layer is formed. A surface (also an upper surface in the drawing) that has the same orientation as the formed side is referred to as a “surface”. The “back side” and “back side” refer to the side (also the side facing the lower side of the drawing) or the side (also the lower side of the drawing) opposite to the “front side” and “front side”.

Further, when applied to a display application or the like, the surface on the observer side may be the back surface instead of the surface defined in the present invention.
The above illustration does not limit the aspect of the electromagnetic wave shielding filter of the present invention. Any device that has substantially the same structure as the technical idea described in the claims of the present invention and that exhibits the same effect can be included in the technical scope of the present invention. .

Hereinafter, the electromagnetic wave shielding filter of the present invention will be described in order from the transparent substrate for each layer.
[Transparent substrate]
The transparent substrate 1 is a layer for reinforcing a copper mesh layer having a low mechanical strength. Therefore, as long as it has light transmittance as well as mechanical strength, it may be selected and used depending on the application, taking into account heat resistance, insulation, etc. as appropriate. Specific examples of the transparent substrate include, for example, a plate and sheet (or film, the same applies hereinafter) made of an organic material such as a transparent resin, and a plate made of an inorganic material such as glass.

  Examples of the transparent resin include polyethylene resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, terephthalic acid-isophthalic acid-ethylene glycol copolymer, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, and nylon. 6, polyamide resins such as polypropylene and polymethylpentene, acrylic resins such as polymethyl methacrylate, styrene resins such as polystyrene and styrene-acrylonitrile copolymer, cellulose resins such as triacetyl cellulose, Examples thereof include imide resins and polycarbonate resins.

In addition, these resins are used as a single or a plurality of types of mixed resins (including polymer alloys) as a resin material, and as a layer, they are used as a single layer or a laminate of two or more layers. In the case of a resin sheet, a uniaxially stretched or biaxially stretched sheet is more preferable in terms of mechanical strength.
Moreover, you may add additives, such as a ultraviolet absorber, a filler, a plasticizer, an antistatic agent, in these resins suitably as needed.

  Examples of the glass include quartz glass, borosilicate glass, and soda lime glass. More preferably, the glass has a low coefficient of thermal expansion, excellent dimensional stability and workability in high-temperature heat treatment, and does not contain an alkali component in the glass. Examples include alkali-free glass and the like, which can also be used as an electrode substrate used as a front substrate of a display.

  The thickness of the transparent substrate is not particularly limited as long as it depends on the application. When the transparent substrate is made of a transparent resin, it is usually about 12 to 1000 μm, preferably 50 to 500 μm. On the other hand, when a transparent base material is a glass plate, about 1-5 mm is usually suitable. In any material, when the thickness is less than the above, the mechanical strength is insufficient and warping, loosening, breakage, and the like occur. When the thickness exceeds the above, the cost is increased due to excessive performance and it is difficult to reduce the thickness.

  The transparent substrate may also be used as a front substrate, which is a component of the display body. However, in the form of using an electromagnetic wave shielding filter as a front filter disposed in front of the front substrate, the thin and light points are used. Thus, the sheet is superior to the plate, and the resin sheet is superior to the glass plate in that it is not broken.

  In this respect, a resin sheet is a preferable material for the transparent substrate, but among the resin sheets, in particular, polyester resin sheets such as polyethylene terephthalate and polyethylene naphthalate have transparency, heat resistance, cost, and the like. In view of this, a biaxially stretched polyethylene terephthalate sheet is more preferable. In addition, although the transparency of a transparent base material is so good that it is high, Preferably the light transmittance which becomes 80% or more by visible light transmittance | permeability is good.

In addition, a transparent substrate such as a resin sheet is appropriately coated on the surface thereof with known easy processes such as corona discharge treatment, plasma treatment, ozone treatment, flame treatment, primer treatment, pre-heat treatment, dust removal treatment, vapor deposition treatment, and alkali treatment. An adhesion treatment may be performed.
The transparent substrate may be colored with a pigment or the like. By coloring, near infrared absorption, neon light absorption, color adjustment, prevention of external light reflection, and the like can be achieved. For example, various conventionally known dyes such as a near-infrared absorber, a neon light absorber, a color adjusting dye, and an external light reflection preventing dye may be added to the transparent substrate of the resin.

[Conductive mesh layer]
The conductive mesh layer 2 is a layer responsible for the electromagnetic wave shielding function and is itself opaque, but by providing an opening with a mesh shape, both electromagnetic wave shielding performance and light transmittance are achieved. Is a layer. In the conductive mesh layer of the present invention, at least one of the front and back surfaces is a blackened surface by blackening treatment, and the total light reflectance (R) measured in accordance with JIS Z8722 of the blackened surface. _SCI) 14% or less, more preferably 12% or less, and those specific _(R SCE _{/ R SCI)} is 0.8 or more diffuse light reflectance to the total light reflectance _{(R SCI) (R SCE)} is there. In the present invention, in order to give the specific reflection characteristics to the blackened surface, a necessary surface of the conductive mesh-like conductor layer 21 usually formed from a metal foil or the like as the main body of the conductive mesh layer. In addition, the blackening layer 22 is formed by blackening treatment, and the exposed surface of the blackening layer is used as the blackening treatment surface. In addition to the blackening layer, other layers such as a rust preventive layer, which will be described later, may be appropriately provided as a constituent layer of the conductive mesh layer in that the mesh shape, which is a shape characteristic of the mesh layer, is maintained. When other layers such as the rust preventive layer are formed on the outermost surface on the side where the observer views the electromagnetic shielding filter in the form in which the electromagnetic shielding filter is used for the display, the outermost layer is blackened. It becomes a surface and needs to have the specific reflection characteristic.

(Mesh conductor layer)
The mesh-like conductor layer 21 is typically formed by etching a metal foil, but other mesh layers are also significant in electromagnetic shielding performance. Therefore, in the present invention, the material and forming method of the mesh-like conductor layer are not particularly limited, and various mesh-like conductor layers in a conventionally known light-transmitting electromagnetic wave shielding filter can be appropriately employed. is there. For example, a mesh-like conductor layer is formed from the beginning on a transparent substrate using a printing method, a plating method, or the like, or initially, the entire surface is formed on a transparent substrate by a plating method. After forming the body layer, it may be a mesh-like conductor layer formed into a mesh shape by etching or the like.

  For example, when the mesh shape of the mesh-like conductor layer is formed by etching, it can be formed by patterning the metal layer laminated on the transparent base material by etching and opening the openings to form a mesh. To laminate a metal layer on a transparent substrate, the metal layer prepared as a metal foil is laminated to the transparent substrate with an adhesive, or the metal layer is deposited, sputtered, plated, etc. without using a laminating adhesive It can also be laminated on a transparent substrate using one or two or more physical or chemical forming methods. In addition, the mesh-like conductor layer by etching can also be formed into a mesh-like mesh-like conductor layer by patterning a single metal foil before lamination on a transparent substrate by etching. This single-layer mesh conductor layer is laminated on a transparent substrate with an adhesive or the like. Among these, the metal foil is made of a transparent base material with an adhesive so that the mesh-like conductor layer having a low mechanical strength can be easily handled and is excellent in productivity, and a commercially available metal foil can be used. A mesh-like conductor layer that is formed into a mesh-like shape by etching and then laminated on a transparent substrate via an adhesive is representative. As the adhesive in this case, a known adhesive such as a non-sticky adhesive or a pressure-sensitive adhesive (pressure-sensitive adhesive layer) may be employed.

  The mesh-like conductor layer is not particularly limited as long as it is a substance having sufficient conductivity to exhibit electromagnetic wave shielding performance, but usually a metal layer is preferable in terms of good conductivity, and the metal layer is as described above. Further, it can be formed by vapor deposition, plating, metal foil lamination or the like. Examples of the metal material of the metal layer or the metal foil include gold, silver, copper, iron, nickel, and chromium. The metal of the metal layer may be an alloy, and the metal layer may be a single layer or multiple layers. For example, in the case of iron, low carbon steel such as low carbon rimmed steel and low carbon aluminum killed steel, Ni-Fe alloy, Invar alloy, and the like are preferable. On the other hand, when the metal is copper, the metal material is copper or a copper alloy. There are rolled copper foil and electrolytic copper foil as the copper foil, but the thinness and uniformity thereof, the adhesion with the blackened layer, etc. Is preferably an electrolytic copper foil.

  In addition, the thickness of the mesh-shaped conductor layer by a metal layer is about 1-100 micrometers, Preferably it is 2-20 micrometers. If the thickness is too thin, it will be difficult to obtain sufficient electromagnetic shielding performance due to an increase in electrical resistance, and if the thickness is too thick, it will be difficult to obtain a high-definition mesh shape, which will reduce the uniformity of the mesh shape. .

In addition, the front and back surfaces of the metal layer to be the mesh-like conductor layer are rough when the adhesion with the adjacent layer such as a transparent adhesive layer for adhesion and lamination with the transparent base material is required. good.
In addition, when the surface of the metal layer that becomes the mesh-like conductor layer is additionally formed with a blackened layer on the surface, it is easy to have the desired micro unevenness and low reflection characteristics even if the blackened layer is thinner. In terms of surface roughness, when a roughness curve is adopted as the contour curve of the surface of the metal layer that becomes the mesh-like conductor layer, the ten-point average roughness RzJIS (JIS B0601 (1994 version) of the contour curve. ) Is preferably 1 μm or more.

(Blackening treatment)
The blackening treatment is for preventing light reflection on the surface of the conductive mesh layer, and the black level of the fluoroscopic image due to reflection of external light on the surface of the conductive mesh layer by the blackening treatment surface formed by the blackening treatment. Is reduced, the black level is improved, and the bright room contrast of the fluoroscopic image is produced, thereby improving the visibility of the image on the display. The blackened surface is preferably provided on all surfaces of the line portion (striated portion) of the conductive mesh layer, but in the present invention, at least one of the front and back surfaces is a blackened surface. The electromagnetic wave shielding filter according to the present invention is installed on the front surface of the display as the side on which the observer sees the side having the blackened surface.

  The blackened surface may be the single conductive mesh layer surface itself. That is, if the conductive mesh layer is a single layer and the surface of the single layer has the specific reflection characteristics, the surface does not need additional blackening treatment. In the present invention, even if there is no such additional blackening treatment, as long as the surface has the above-mentioned specific reflection characteristics, the resulting surface has the same physical properties. It will be included in the present invention.

  However, normally, a conductive layer such as a metal layer is employed for the conductive mesh layer in terms of conductivity necessary for the electromagnetic wave shielding function, and the surface color of such a conductive layer is usually a metallic color. In many cases, it is not black and does not become the blackened surface in the present invention. Therefore, in such a case, a blackening treatment such as forming a blackening layer to be described later is performed on the surface, and a blackening treatment surface is realized on the surface of the formed blackening layer. Further, providing a blackened layer on the surface means that the surface is formed from the surface to the inside by etching or the like in addition to providing the layer (mesh-like conductor layer or the like) constituting the surface by plating or the like. The layer itself may be changed to a blackened layer. Therefore, normally, the conductor mesh layer 2 is a layer in which a blackened layer 22 is provided on at least one of the mesh-like conductor layer 21 that bears an electromagnetic wave shielding function due to conductivity and at least the front and back surfaces thereof ( (See FIG. 2).

  Therefore, when the target surface of the blackening treatment surface having specific reflection characteristics according to the present invention is exemplified by the formation surface of the blackening layer 22, both the front and back surfaces of the line portion of the conductive mesh layer 2 (FIG. 2A) , Only the front surface (Fig. 2 (B)), only the back surface (Fig. 2 (C)), only the front and side surfaces (both sides or one side), only the back surface and side surfaces (both sides or one side), the entire surface (both sides and both sides) FIG. 2D) and the like. However, this is shown for the blackened surface having the specific reflection characteristics, and in addition to the blackened surface shown above, it normally falls within the category of the blackened surface, but the desired reflective characteristics. You may have the blackened surface which does not have. For example, the entire surface normally falls within the category of a blackened surface, but only the surface is a blackened surface having desired reflection characteristics defined in the present invention.

(Blackening surface)
The blackened surface of the conductive mesh layer in the present invention exhibits black or a color close to black (brown, amber, deep green, etc., including black) and conforms to JIS Z8722. measured total light reflectance _{(R SCI)} 14% or less, preferably 12% or less, and the total light reflectance diffuse light reflectance for _{(R SCI)} ratio _{(R SCE) (R SCE /} R SCI) is The optical property is 0.8 or more.

  By optimizing the blackened surface so as to have the specific reflection characteristics as described above, it looks black even in wet color, and it is transparent through external light reflection on the conductive mesh layer surface without blackening A reduction in the black level of the image is prevented, and the black level can be improved. These can be achieved even in a wet color in which a transparent resin layer is further laminated on the blackened surface. When the electromagnetic wave shielding filter according to the present invention is provided, the visibility of the display image is improved by providing a bright room contrast feeling of the fluoroscopic image. Can be improved.

The total light reflectance of the blackened surface in the present invention is 14% or less, preferably 12% or less, more preferably 8% or less. The lower the total reflectance, the more preferable because it can appear black in wet color. The total reflectance of the blackened surface is usually 0.1% or more because it is difficult to achieve technically.
The ratio of total light reflectance of the black oxide treatment surfaces according to the present invention diffuse light reflectance for _{(R SCI) (R SCE)} (R SCE / R SCI) is less than 0.8, preferably, 0 .9 or more, more preferably 0.95 or more. The ratio of the total light reflectance diffuse light reflectance for _{(R SCI) (R SCE)} (R SCE / R SCI) , the more components of diffuse reflection at the total reflection is increased closer to 1, the components of the specular reflection is reduced In this respect, the black level can be improved without so-called black light.

In order to make the reflection characteristic of the blackened surface according to the present invention the above-mentioned specific reflective characteristic, it is preferable to adjust the blackening color and the shape of the micro unevenness by appropriately adjusting the conditions of the blackening process.
As an aspect for setting the reflection characteristics of the blackened surface according to the present invention to the above-mentioned specific reflective characteristics, it is preferable that the blackened surface has fine irregularities from the viewpoint of increasing the diffuse reflection component. The specific reflection characteristic depends on various characteristics of the minute unevenness on the blackened surface.

  Among the minute irregularities, as one form of a preferable shape for obtaining the specific reflection characteristic, when a roughness curve is adopted as the contour curve of the surface of the blackened surface, the ten-point average roughness of the contour curve RzJIS (JIS B0601 (1994 edition)) is preferably 1 μm or more, more preferably 2 μm or more. Here, the contour curve of the blackened surface includes a cross-section curve, a roughness curve, and a waviness curve. In the present invention, a roughness curve R obtained by subtracting the waviness curve from the cross-section curve is employed. As described above, when the blackened surface has a ten-point average roughness RzJIS (JIS B0601 (1994 edition)) of the contour curve of 2 μm or more, the specific reflection characteristics are likely to be obtained. The ten-point average roughness RzJIS (JIS B0601 (1994 version)) of the contour curve is more preferably 2 to 5 μm. In addition, from the viewpoint of ensuring the strength of the conductive mesh layer and the electromagnetic wave shielding property, the value of RzJIS is preferably set to a value of about half or less of the thickness of the conductive mesh layer.

In addition, as a form of a preferable shape for obtaining the specific reflection characteristic among the minute unevenness, a probability density function [JIS B0601 (JIS B0601) of the contour curve when a roughness curve is adopted as the contour curve of the minute unevenness. 2001))), the shape near the peak of the probability density is a curve obtained by smoothing the probability density function, and the probability density is taken on the vertical axis and taken upward (the horizontal axis is the roughness curve). (Amplitude value of unevenness), and a case of an upwardly convex curve shape. Note that “upwardly convex” means that the probability density is on the vertical axis and the upward direction is a positive value of the probability density.
If FIG. 3 demonstrates, FIG. 3 (A) will show the roughness curve R as a contour curve, and code | symbol ML is an average line in the figure. In addition, although there exist a cross-sectional curve, a roughness curve, and a waviness curve as a contour curve, the roughness curve R which subtracted the waviness curve from the cross-sectional curve is employ | adopted by this invention. FIG. 3B shows a probability density function ADF of the roughness curve and a load curve BAC (cumulative curve) of the roughness curve calculated from the contour curve of the roughness curve R of FIG. In the figure, Rp represents the maximum peak height of the roughness curve, and Rv represents the maximum valley depth of the roughness curve. FIG. 3C is a graph obtained by rotating FIG. 3B by 90 degrees in the counterclockwise direction so that the probability density becomes the vertical axis in the positive direction on the upper side of the drawing. In FIG. 3C, the horizontal axis between Rp and Rv and the vertical axis of the probability density are true scales and not logarithmic scales. Since the shape indicated by the probability density function ADF is finely uneven as shown in FIG. 3C, the probability density curve Adc is a smooth curve as shown in FIG. 4A. Since the probability density function ADF obtained by measuring the surface becomes a jagged graph such as a bar graph as shown in FIGS. 3B and 3C, it is measured as a smooth probability density curve by the least square method or the like. Capturing the features of minute irregularities on the surface. Note that smoothing the probability density function means that if the surface measurement is repeated an infinite number of times, the jagged graph will be averaged, and the probability density function will eventually approach a smooth curve. This corresponds to approximately obtaining from the result of the number of times or a small number of measurements. Then, like the probability density curve Adc shown in FIG. 4 (A), the blackening treatment surface in which the shape in the vicinity of the peak of the probability density curve is a convex curve shape is as shown in FIG. 4 (B). A blackening process in which the shape of the shape near the peak is pointed and has a cusp, and the curve located on the left and right of the straight line passing through the peak vertex and parallel to the vertical axis has a convex downward curve shape. Gives better anti-reflection performance than surface.
The curve shape of the probability density function as described above is often obtained, for example, when fine irregularities are superimposed on rough irregularities.

  In order to make the micro unevenness of the blackening treatment surface into the specific micro unevenness as described above, the conditions of the blackening process when forming the blackening layer as described later are appropriately adjusted, or the blackening process is performed. The fine unevenness of the surface of the lower surface of the target surface, that is, the blackened surface is adjusted. In addition, when the base surface has a fine uneven surface rather than a mirror surface, when a blackened layer is additionally formed, it is easy to have desired fine unevenness and reflection characteristics even if it is thinner. A preferable shape as the minute unevenness of the lower ground is as described above. Preferred conditions for the blackening treatment when forming the blackened layer will be described later.

  Moreover, the preferable black density of the blackened surface is 0.6 or more. In addition, the measurement method of black density was set to the density standard ANSIT as an observation viewing angle of 10 degrees, an observation light source D50, and an illumination type using GRETAG SPM100-11 (trade name, manufactured by Kimoto Co., Ltd.) of COLOR CONTROL SYSTEM. The specimen is measured after calibration.

(Blackening layer)
The blackening layer 22 is a layer provided for imparting the above-described blackening treatment surface. The blackening layer 22 may be any layer as long as it exhibits a dark color such as black and satisfies basic physical properties such as adhesion. It can be adopted as appropriate.
Therefore, as the blackening layer, an inorganic material such as a metal, an organic material such as a black colored resin, or the like can be used. For example, as the inorganic material, a metal, an alloy, a metal oxide, a metal compound of metal sulfide, It is formed as a metal-based layer. As a method for forming the metal layer, various conventionally known blackening methods can be appropriately employed. Especially, the blackening process by a plating method is preferable at adhesiveness, uniformity, ease, etc. As a material for the plating method, for example, a metal such as copper, cobalt, nickel, zinc, molybdenum, tin, or chromium, a metal compound, or the like is used. These are superior to the case of cadmium or the like in terms of adhesion and blackness.

  When the mesh-like conductor layer is made of copper, such as copper foil, a preferable plating method for the blackening treatment for forming the blackened layer is a mesh-like conductor layer made of copper (because it is performed before forming the mesh shape). There is a cathodic electrodeposition plating method in which, if present, the previous conductor layer) is subjected to cathodic electrolysis in an electrolytic solution made of sulfuric acid, copper sulfate, cobalt sulfate or the like, and cationic particles are deposited. According to this method, the rough surface can be obtained simultaneously with the black color by the adhesion of the cationic particles. Copper particles and copper alloy particles can be adopted as the cationic particles. The copper alloy particles are preferably copper-cobalt alloy particles, and the average particle size is preferably 0.001 to 1 μm. A blackened layer composed of a copper-cobalt alloy particle layer is obtained by the copper-cobalt alloy particles. The cathodic electrodeposition method is also preferable in that the average particle diameter of the cationic particles to be adhered is adjusted to 0.001 to 1 μm. When the average particle diameter exceeds the above range, the density of the adhered particles is reduced, blackness is reduced and unevenness occurs, and particle falling off (powder falling) is likely to occur. On the other hand, even if the average particle diameter is less than the above range, the blackness is lowered. In the cathodic electrodeposition method, when the treatment is performed at a high current density, the treated surface becomes cathodic, and activated by reducing hydrogen generation, the adhesion between the copper surface and the cationic particles is remarkably improved.

  Moreover, as a blackening layer, black chrome, black nickel, a nickel alloy, etc. are preferable, and as this nickel alloy, they are a nickel-zinc alloy, a nickel-tin alloy, and a nickel-tin-copper alloy. In particular, the nickel alloy has a good degree of blackness and conductivity, can also impart a rust prevention function to the blackened layer (becomes a blackened layer and a rustproof layer), and can omit the rustproof layer. In addition, since the particles of the blackened layer are usually needle-like, the appearance is likely to change due to external force, but the blackened layer made of nickel alloy is difficult to deform and the appearance is difficult to change in the post-processing step. Benefits. In addition, the formation method of a nickel alloy as a blackening layer may be a known electrolytic or electroless plating method, and the nickel alloy may be formed after nickel plating.

  Alternatively, in the case where the mesh-like conductor layer is copper, there is a method in which this is oxidized by reacting with an alkaline solution to easily precipitate copper oxide fine particles on the surface. For example, as described in JP-A-2002-9484, a method of immersing a copper mesh layer in a mixed solution of a copper pyrophosphate aqueous solution, a potassium pyrophosphate aqueous solution, and an ammonia aqueous solution, and the like can be mentioned.

In the present invention, in order to make the blackened surface particularly have the above-mentioned reflection characteristics, a method for forming the blackened layer is appropriately selected according to the surface state of the mesh-like conductor layer.
For example, when the surface roughness of the mesh-like conductor layer made of copper is relatively large and RzJIS is 1 μm or more, it is preferable to form the blackened layer by black nickel plating. Further, when the surface roughness of the mesh-like conductor layer is relatively small and RzJIS is less than 1 μm, a cathodic electrodeposition method using copper particles or copper-cobalt alloy particles having an average particle diameter of about 1 nm to 1 μm, Alternatively, the blackened layer is preferably formed by forming copper oxide fine particles having an average particle diameter of about 1 nm with an alkaline solution.

(Mesh shape)
In addition, the shape of the mesh layer 2 as a mesh shape is not particularly limited, but a square is typical as the shape of the opening of the mesh. The plan view shape of the opening is, for example, a triangle such as a regular triangle, a square such as a square, a rectangle, a rhombus, or a trapezoid, a polygon such as a hexagon, a circle, an ellipse, or the like. The mesh has a plurality of openings having these shapes, and the openings are usually line-shaped line portions having a uniform width. Usually, the openings and the line portions have the same shape and the same size on the entire surface. As an example of a specific size, the width of the line portion between the openings is preferably 5 to 25 μm in terms of the aperture ratio and the invisibility of the mesh. The size of the opening is [line interval or line pitch] − [line width]. In terms of this [line interval or line pitch], the aperture size is 150 μm to 500 μm, and the aperture ratio (total area of openings / mesh portion) The total area) is preferably 80 to 95% from the viewpoint of compatibility between light transmittance and electromagnetic wave shielding properties.
Note that the bias angle (the angle formed between the mesh line portion and the outer periphery of the electromagnetic wave shielding filter) may be appropriately set to an angle at which moire is difficult to occur in consideration of the pixel pitch of the display and the light emission characteristics.

The mesh layer 2 may have a mesh shape over the entire surface of the electromagnetic wave shielding filter. However, a portion requiring light transmission is used as a mesh-shaped mesh portion, and other portions (for example, all four sides are surrounded in a frame shape). It is good also as a non-mesh part. The non-mesh portion is a portion other than the mesh portion, and is a region where light transmittance is not required as a surface. Usually, a non-mesh part is provided on the outer periphery of the mesh part. The non-mesh part is usually used for grounding. The non-mesh part used for grounding is usually framed around all four sides. In addition, the frame-like non-mesh portion is an external image that enhances the appearance of the image seen through the mesh portion such as a display image by surrounding the image with a frame shape (for example, a black frame) to enhance the image. It can also be used as a frame. The non-mesh portion preferably exposes the conductor layer in at least a portion of the ground when it is grounded.
Although the specific size of the non-mesh part depends on how it is used, when the frame is in the shape of a ground part or outer frame, the width of the frame is about 15 to 100 mm, and in particular, it is generally 30 to 40 mm. It is.

(Rust prevention layer)
As the mesh layer 2, other layers may be appropriately formed or processed as necessary. For example, when the durability against rust is insufficient, a rust prevention layer may be provided. The rust preventive layer is also the blackened layer described above, but as long as it maintains the mesh shape that is the geometric feature of the mesh layer, the present invention regards it as a constituent layer of the mesh layer included in the mesh layer. .
The rust-proof layer may be applied to the surface of the mesh layer that is easily rusted, but if it is further applied to the blackened surface, the blackened surface after being applied (actually the rust-proof layer surface) In the present invention, at least one of the front and back surfaces is a surface having desired reflection characteristics. The coating surface of the mesh layer by the rust preventive layer includes only the front surface, only the back surface, both front and back surfaces, only the side surfaces (both sides or one side), the front surface and both side surfaces, the back surface and both side surfaces, the front and back both surfaces and both side surfaces, and the like.

  The rust preventive layer is not particularly limited as long as it does not rust more easily than the mesh-like conductor layer coated with the rust preventive layer, such as an inorganic material such as metal, an organic material such as resin, or a combination thereof. In some cases, the blackened layer is also covered with a rust-preventing layer, so that the particles of the blackened layer can be prevented from dropping or deformed, and the blackened layer can be increased in blackness. In this respect, when the mesh-like conductor layer is formed of a metal foil, when the blackened layer is provided on the metal foil on the transparent substrate by the blackening treatment, the blackened layer is prevented from falling off or being altered. In terms of meaning, it is preferably provided before lamination of the transparent substrate and the metal foil.

  A conventionally well-known thing should just be employ | adopted for a rust prevention layer suitably, for example, is a metal thru | or alloys, such as chromium, zinc, nickel, tin, copper, or the layer of a metal compound of a metal oxide. These can be formed by a known plating method or the like. Here, if it shows an example of a rust prevention layer preferable at points, such as a rust prevention effect and adhesiveness, the chromium compound layer obtained by carrying out a chromate process after galvanization will be mentioned.

In the case of chromium, chromate (chromate) treatment or the like may be used. Note that the chromate treatment is performed by bringing a chromate treatment solution into contact with the treatment surface.
In the chromate treatment, galvanization before the treatment is preferable in terms of adhesion and rust prevention effect. In addition, the rust preventive layer may contain a silicon compound such as a silane coupling agent in order to improve acid resistance during etching or acid cleaning.
In addition, the thickness of a rust prevention layer is about 0.001-2 micrometers normally, Preferably it is 0.01-1 micrometer.

[Transparent resin layer]
As illustrated in the cross-sectional view of FIG. 1 (B), the transparent resin layer 3 fills the surface irregularities of the conductive mesh layer 2 and flattens the surface on the mesh layer side, thereby adhering the adherend on the mesh layer side. This is a layer provided as necessary in order to prevent air entrapment or the like and to protect the mesh layer from external force when laminating with an adhesive or the like. In terms of protection, this transparent resin layer is also a surface protective layer. As shown in FIG. 1C, the transparent resin layer 3 can also be used as an adhesive layer that is interposed between the adherend 4 and the conductive mesh layer 2 and adheres both. Such a transparent resin layer 3 can be formed by applying a liquid composition containing a resin to the concavo-convex surface of the conductive mesh layer 2 laminated on the transparent substrate 1 by coating or the like. The liquid composition is not particularly limited as long as it contains a transparent resin, and a known resin may be appropriately employed. For example, a thermoplastic resin, a thermosetting resin, an ionizing radiation curable resin, or the like. For example, as the thermoplastic resin, acrylic resin, polyester resin, thermoplastic urethane resin, vinyl acetate resin, etc., and as the thermosetting resin, thermosetting urethane resin, epoxy resin, thermosetting acrylic resin, etc. The ionizing radiation curable resin is an acrylate resin that is cured by ultraviolet rays or an electron beam. Among these, an ionizing radiation curable resin that can be coated and formed in a solvent-free or solvent-free state is a preferred resin in that it easily fills irregularities due to the mesh layer.

  Note that the transparent resin layer only needs to fill the opening of the conductive mesh layer for the purpose of planarization, but may be formed including the line portion of the mesh layer as shown in FIG. When the transparent resin layer is provided including just above the line part, when the surface of the mesh layer in contact with the transparent resin layer is a blackened surface, the transparent resin layer gives a wet color. In particular, in the present invention, even in the case of this wet color, since the light reflection preventing effect is high, the configuration in which the transparent resin layer is formed including the portion directly above the line portion is one suitable configuration.

[Other layers: adherend, optical filter layer, surface protective layer, transparent adhesive layer, etc.]
The adherend is, for example, an optical filter layer (film, sheet, plate), a surface protective layer (film, sheet, plate) or the like. The optical filter function of the optical filter layer includes near-infrared absorption, antireflection (including antiglare), color tone adjustment (neon light absorption, improved color reproducibility), and external light antireflection. Further, the functions of the surface protective layer are contamination prevention, scratch resistance, and the like. These may be appropriately selected from conventionally known ones. In addition, the optical filter layer and the surface protective layer may be formed on the mesh layer, the transparent resin layer, or in the case of the optical filter layer on another optical filter layer by coating or the like, not as an adherend of the transparent resin layer. it can.

  Moreover, the adherend 4 may be laminated | stacked on the transparent base material 1 side like FIG.1 (D) contrary to FIG.1 (C). When the transparent substrate and the adherend are not adhesive to each other, they are appropriately laminated with a transparent adhesive layer interposed therebetween. As the transparent adhesive layer, a known adhesive such as a non-sticky adhesive or a pressure-sensitive adhesive (pressure-sensitive adhesive layer) may be employed. The transparent adhesive layer can be said to be one form of a transparent resin layer. Further, the adherend may be laminated on both the front and back surfaces of the electromagnetic wave shielding filter for display. In that case, the type (function) of the adherend can be properly used on the front and back sides.

[Others]
In addition, in the resin constituting the electromagnetic shielding filter such as a transparent substrate, transparent resin layer, transparent adhesive layer, and adherend, an external light reflection preventing dye, a neon light absorber, a color adjusting dye, etc. You may add a well-known pigment | dye suitably in an electromagnetic wave shield filter.

  Further, FIG. 1 for explaining the details of the mesh layer and FIG. 2 for explaining the blackening treatment surface are examples and do not limit the form of the electromagnetic wave shielding filter of the present invention. Any device that has substantially the same structure as the technical idea described in the claims of the present invention and that exhibits the same effect can be included in the technical scope of the present invention. .

Hereinafter, the present invention will be specifically described with reference to examples. These descriptions do not limit the present invention. In the examples, parts represent parts by weight unless otherwise specified.
<Example 1>
First, as a transparent base material 1, an electrolytic copper foil having a thickness of 10 μm is bonded to a surface of a continuous belt-like uncolored transparent biaxially stretched polyethylene terephthalate film (thickness: 100 μm) with a two-component curable urethane resin. A continuous strip-shaped copper-clad laminate sheet was prepared by dry lamination using an agent.
Next, the copper foil of the copper-clad laminate sheet is processed into a mesh shape by etching using a photolithography method, thereby creating a mesh laminate sheet in which the mesh-like conductor layer 21 is formed on the transparent substrate 1. did.
Next, the surface of the mesh laminated sheet is subjected to a blackening treatment for forming a blackened layer 22 by black nickel plating on the surface on the mesh-like conductor layer side, and the surface (and both side surfaces) of the conductive mesh layer 2 is applied. An electromagnetic wave shielding filter 10 as shown in FIG. 1A having a blackened surface having the reflection characteristics shown in Table 1 was produced. Note that the formed mesh has a square opening, a line width of 25 μm, and a line pitch of 150 μm. Further, the entire circumference of the four sides of the mesh portion was a frame-shaped non-mesh portion.

  Further, as a transparent resin layer 3 that also serves as an adhesive layer with respect to the mesh layer side surface of the electromagnetic wave shielding filter 10, a part of the inner periphery of the acrylic resin coating liquid is exposed so that the non-mesh portion is partially exposed. Including intermittent coating on the mesh layer by the intermittent die coating method. Next, an 80 μm-thick triacetyl cellulose film is used as a substrate and a fluororesin-based low refractive index layer is formed as an antireflection layer on the surface of the coating film after the solvent of the coating liquid is dried. The antireflection film was laminated with the base material side facing the mesh layer side (the antireflection layer was exposed on the outermost surface), and a desired electromagnetic wave shielding filter with an antireflection function was produced.

<Examples 2 to 5>
An electromagnetic wave shielding filter 10 as shown in FIG. 1 (A) having a blackened surface having the reflection characteristics shown in Table 1 was produced in the same manner as in Example 1 except that the electrolytic copper foils were changed in Example 1. . Next, in the same manner as in Example 1, an electromagnetic wave shielding filter with an antireflection function was produced.

<Example 6>
Instead of changing the electrolytic copper foil in Example 1 and forming the blackened layer 22 by black nickel plating, copper particles having an average particle diameter of 1 nm are attached by the cathodic electrodeposition plating method to form the blackened layer 22. Other than the formation, an electromagnetic wave shielding filter 10 as shown in FIG. 1A having a blackened surface having the reflection characteristics shown in Table 1 was produced in the same manner as in Example 1. Next, in the same manner as in Example 1, an electromagnetic wave shielding filter with an antireflection function was produced.

<Example 7>
In Example 1, the electrolytic copper foil was changed and, instead of forming the blackened layer 22 by black nickel plating, copper-cobalt alloy particles having an average particle diameter of 0.1 μm were adhered by cathodic electrodeposition plating. Except that the blackening layer 22 was formed, an electromagnetic wave shielding filter 10 as shown in FIG. 1A having a blackening treatment surface having the reflection characteristics shown in Table 1 was produced in the same manner as in Example 1. Next, in the same manner as in Example 1, an electromagnetic wave shielding filter with an antireflection function was produced.

<Example 8>
Instead of changing the electrolytic copper foil in Example 1 and forming the blackened layer 22 by black nickel plating, copper-cobalt alloy particles having an average particle diameter of 0.2 μm were adhered by cathodic electrodeposition plating. Except that the blackening layer 22 was formed, an electromagnetic wave shielding filter 10 as shown in FIG. 1A having a blackening treatment surface having the reflection characteristics shown in Table 1 was produced in the same manner as in Example 1. Next, in the same manner as in Example 1, an electromagnetic wave shielding filter with an antireflection function was produced.

<Example 9>
In Example 1, the electrolytic copper foil was changed, and instead of forming the blackened layer 22 by black nickel plating, copper particles having an average particle diameter of 1 μm were attached by cathodic electrodeposition plating, and then further cobalt plating was performed. An electromagnetic wave shielding filter 10 as shown in FIG. 1A having a blackening treatment surface having the reflection characteristics shown in Table 1 was produced in the same manner as in Example 1 except that the blackening layer 22 was formed in the same manner. Next, in the same manner as in Example 1, an electromagnetic wave shielding filter with an antireflection function was produced.

<Example 10>
First, as the transparent substrate 1, a continuous belt-shaped uncolored transparent biaxially stretched polyethylene terephthalate film having a thickness of 100 μm and a polyester resin primer layer formed on one side was prepared. On the primer layer of this transparent base material, a nickel-chromium alloy layer having a thickness of 0.1 μm and a copper layer having a thickness of 0.2 μm were sequentially provided by sputtering to form a conductive treatment layer. On the surface of the conductive treatment layer, a copper plating layer having a thickness of 2.0 μm is provided by an electrolytic plating method using a copper sulfate bath, and the conductive layer composed of the conductive treatment layer and the copper plating layer is an adhesive layer on the transparent substrate. A copper-clad laminate sheet was directly formed without any interposition. Next, the copper foil of the copper-clad laminate sheet is processed into a mesh shape by etching using a photolithography method, thereby creating a mesh laminate sheet in which the mesh-like conductor layer 21 is formed on the transparent substrate 1. did. Next, copper oxide fine particles having an average particle diameter of 0.1 μm are formed on the surface of the mesh laminated sheet on the mesh-like conductor layer side by oxidation using a mixed solution of copper pyrophosphate aqueous solution, potassium pyrophosphate aqueous solution, and aqueous ammonia. An electromagnetic wave shielding filter 10 as shown in FIG. 1A having a blackening treatment surface having the reflection characteristics shown in Table 1 on the surface (and both side surfaces) of the conductive mesh layer 2 is applied. Produced. Otherwise, an electromagnetic wave shielding filter with an antireflection function was produced in the same manner as in Example 1.

<Comparative Example 1 and Comparative Example 2>
An electromagnetic wave shielding filter was produced in the same manner as in Example 1 except that the electrolytic copper foil was changed in Example 1.

[Performance evaluation]
First, Table 1 shows the characteristics of the blackened surface and the performance evaluation results for the electromagnetic wave shielding filters of Examples and Comparative Examples.
The reflection characteristics and minute irregularities of the blackened surface were evaluated on the blackened surface of the mesh layer surface of the non-mesh part located on the outer periphery of the mesh part of the mesh layer. In addition, the anti-reflection performance can be eliminated at the non-mesh part (however, the inner part where the anti-reflective film is laminated through the transparent resin layer and has a wet color) because the influence of the opening of the mesh part can be eliminated. It was.

(1) Reflection characteristics of the blackened surface The total light reflectance (%) measured in accordance with JIS Z8722 on the blackened surface is a spectrocolorimeter (for example, CM-3600d manufactured by Konica Minolta Sensing Co., Ltd.). Is set to the reflection mode, the light source is the standard light D65, and the field of view is 2 °, and the (integral) intensity of the total reflection light combining both the diffuse reflection light and the specular reflection light of the reflected light is used as the detector. Was set to the SCI mode to measure the Y value (Y of tristimulus values XYZ). Further, the diffused light reflectance (%) according to JIS Z8722 of the blackened surface is similarly obtained by using a spectrocolorimeter, and using the same light source and field of view, and absorbing and blocking specular reflection light with an optical trap. The detector was set to the SCE mode in which the (integral) intensity of only the diffuse reflected light out of the reflected light was set, and the Y value (Y of tristimulus values XYZ) was measured.

(2) Light reflection prevention performance The light reflection prevention performance of the electromagnetic wave shielding filter was evaluated by measuring the total light reflectance on the blackened surface side in a state of a wet color after laminating the transparent resin layer and the light reflection prevention film. (%) Was measured from the antireflection film side (“AR” in the table). The measuring method of the total light reflectance was the same as the measuring method of the total light reflectance in (1). The total light reflectivity (AR) in the wet color state is preferably small, and the case where the total light reflectivity is less than 5% is an allowable range for the light reflection preventing performance.

(3) Ten point average roughness of the blackened surface RzJIS, Ra
The micro unevenness of the blackened surface was evaluated by the ten-point average roughness RzJIS (JIS B0601 (1994 edition), unit: μm) of the contour curve when a roughness curve was adopted as the contour curve of the micro unevenness. As a reference value, the center line average roughness Ra (JIS B0601, unit is μm) of the fine irregularities was also measured.

(4) Probability density curve Regarding the minute unevenness on the blackened surface, the probability density function [JIS B0601 (2001 version) rule] of the contour curve when the roughness curve is adopted as the contour curve of the minute unevenness is the probability density. When the shape near the peak (top) of the curve is a curve obtained by smoothing the probability density function, the probability density is plotted on the vertical axis and taken upward (the horizontal axis is the amplitude value of the unevenness of the roughness curve) Whether or not the shape is composed of an upwardly convex curve was examined. And when the shape near the peak is an upward convex curve as shown in FIG. 4 (A), the shape near the peak is a sharp shape as shown in FIG. 4 (B). A case where a curve having a cusp and a left-right curve with respect to a straight line passing through the peak vertex and parallel to the vertical axis is abbreviated as “convex downward”.

<Summary of results>
As shown in Table 1, the total light reflectance (R _SCI ) measured according to JIS Z8722 on the blackened surface is 14% or less, and the diffused light reflectance (R _SCI ) relative to the total light reflectance (R _SCI ) _In each of the examples in which the ratio (S _SCE / R _SCI ) of _SCE ) is 0.8 or more, the total light reflection in a wet color state as compared with the comparative examples that do not satisfy these reflection characteristics. The rate (AR) was small, and more excellent antireflection performance was obtained. In Examples and Comparative Examples other than Examples 8 to 10, the arithmetic average roughness Ra of the surface is in the range of 0.2 to 1.0 μm, and all of them have been conventionally good. It was found that there was a difference in performance depending on the reflection characteristics. Further, Examples 8 to 10 reveal that good antireflection performance can be obtained even if the surface is outside the range of the arithmetic average roughness Ra, which has been considered good in the past.

Claims (3)

In an electromagnetic wave shielding filter having at least a conductive mesh layer on a transparent substrate, at least one of the front and back surfaces of the conductive mesh layer is blackened, and the blackened surface conforms to JIS Z8722 and the total light reflectance was measured _{(R SCI)} is not more than 14%, and the total light reflectance diffuse light reflectance for _{(R SCI)} ratio _{(R SCE) (R SCE /} R SCI) is 0.8 or more An electromagnetic wave shielding filter characterized by being.   When the blackened surface has minute irregularities and a roughness curve is adopted as the contour curve of the minute irregularities, the ten-point average roughness RzJIS (JIS B0601 (1994 version)) of the roughness curve is 2 μm or more. The electromagnetic wave shielding filter according to claim 1, wherein The electromagnetic wave shielding filter according to claim 1 or 2, wherein a transparent resin layer is laminated on the blackened surface of the conductive mesh layer having the blackened surface. .

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