JP2010118396A - Optical filter and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter and a method of manufacturing the optical filter by which air bubbles are formed because of unevenness due to a metal pattern and the sectional shape of the pattern and then remaining air bubbles make transparency and antireflection effect insufficient, even when laminating is carried out with an adhesive layer, serving as a flattening layer, of an antireflective film with the adhesive layer. <P>SOLUTION: The method of manufacturing the optical filter having electromagnetic shielding and optical mirror-surface antireflective properties includes: a metal pattern layer forming process of forming, on a transparent substrate, a metal pattern layer such that the area of a section cut with a virtual plane parallel to the transparent substrate is represented by a decrease function S(z) of the distance (z) from the transparent substrate; and an optical mirror-surface antireflective layer transfer process of preparing a transfer sheet formed by laminating an optical mirror-surface antireflective layer and an adhesive layer on a peelable base material, stacking the transfer sheet such that its adhesive layer side faces the metal pattern layer side and pressing it against the metal pattern layer, and peeling and removing the peelable base material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical filter, and more particularly to an optical filter having electromagnetic wave shielding properties and optical specular reflection prevention properties, and a method for manufacturing the same, which are suitable for being placed on the front surface of an image display device (display).

  Currently, electromagnetic wave shielding filters are used for applications such as disposing on the front surface of a display, and among them, there are typically plasma display (also referred to as PDP) applications. In an electromagnetic wave shielding filter for a plasma display, a mesh pattern is often used as a metal pattern that achieves both electromagnetic wave shielding performance and light transmittance. A metal pattern (EMI shielding 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 photolithography (Patent Document 1, Patent Document). 2).

As a metal material of the metal foil, there are many documents that are not particularly limited in Patent Documents (Patent Documents 1 and 2). Examples of metals include high conductivity, such as aluminum (Patent Document 2), in addition to copper. However, in actuality, the EMI shielding mesh of the electromagnetic shielding filter distributed on the market uses only copper, specifically, copper foil, and does not use aluminum foil and has not been put into practical use.
In the present invention, the term “electromagnetic wave” means an electromagnetic wave in the vicinity of the KHz to GHz band whose frequency is centered on the above range. It does not include infrared rays, visible rays, ultraviolet rays, X-rays, etc. (for example, electromagnetic waves having a frequency in the infrared band are referred to as infrared rays).

In addition, the display filter is required to have an electromagnetic wave shielding property and an optical filter function such as antireflection of extraneous light. When an antireflection agent is applied to a transparent substrate on which a metal pattern is formed, the metal pattern layer and the transparent substrate are used. As a result, uneven coating of the antireflective agent and mixing of bubbles occur, and the antireflection effect becomes insufficient. In order to solve this problem, a transparent flattening layer for flattening the unevenness between the metal pattern layer and the transparent substrate is provided by coating, and an antireflection layer having a lower refractive index than the flattening layer is provided on the upper surface. It has been proposed to provide the film by coating or sheet lamination (Patent Document 3).
However, even in that case, the air in the concave portion of the metal pattern is already completely and quickly replaced with the flattening layer / adhesive layer when the adhesive layer itself that also serves as the flattening layer is coated on the metal pattern. The air bubbles stay in the recesses, and light transmission of the residual bubbles or [haze (fogging value) increase] reduces transparency, or the antireflection effect is insufficient. .

JP 2003-318596 A Japanese Patent No. 3388682 JP-A-11-337702

In recent years, in an optical filter having an electromagnetic shielding property and an optical specular reflection preventing property by a metal pattern layer, in the process of laminating the electromagnetic shielding layer and the optical specular reflection preventing layer, bubbles generated in the flattening layer and the adhesive layer cause haze. It has been regarded as a problem because it increases and obstructs transparency.
Therefore, we have intensively studied the cross-sectional shape that constitutes the convex shape of the metal pattern and the ease of air bubble removal when laminating the optical specular antireflection layer, and the tip side of the cross-section is tapered as it moves away from the transparent substrate. In some cases, it has been found that the bubbles in the metal pattern recesses are easily removed and hardly remain.
Further, in the past, expensive electromagnetic wave shielding filters have been a hindrance in promoting the spread of image display devices (displays), but since aluminum foil is cheaper than copper foil, electromagnetic wave shielding filters using this are: Contributes to cost reduction.
However, it has been found that the practical use of the aluminum pattern layer has the following problems to be solved. The following problems are not noticeable when the line width and thickness of the pattern are about 100 μm or more. It has also been found that the line width and thickness of the pattern are particularly manifested when the line width and thickness are reduced to about 10 to 20 μm or less in order to pursue transparency for high-quality display applications.

(A) Aluminum itself has high activity and an aluminum oxide film is present 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. In addition, as described above, the oxide film becomes a hindrance even when the aluminum pattern is stably tapered with good reproducibility in order to prevent residual bubbles.

  As a result, a fine pattern (for example, a line width of 10 to 20 μm and a pattern thickness of about 10 to 20 μm) required by the image display device cannot be obtained as compared with the copper foil. Giza leads to unevenness in the area ratio of the opening that realizes light transmittance, leading to unevenness in the surface of the display screen, disconnection leads to deterioration in electromagnetic wave shielding performance, and improvement in transparency due to residual bubbles is not improved. It was learned that it would be sufficient.

That is, the object of the present invention is to generate bubbles due to unevenness due to the metal pattern and the cross-sectional shape of the pattern even when laminating the optical specular antireflection layer through the adhesive layer also serving as a planarization layer, An object of the present invention is to provide an optical filter capable of preventing the transparency and antireflection effect from being insufficient due to light diffusion, and a method for manufacturing the same.
In addition, it eliminates poor pattern accuracy of the aluminum pattern formed by chemical etching, which occurs when the material of the metal pattern is changed from copper to inexpensive aluminum, and bubbles are generated due to the cross-sectional shape of the aluminum pattern. An object is to provide an optical filter capable of preventing the transparency and antireflection effect from becoming insufficient, and a method for manufacturing the same.

The present invention
(1) A metal pattern layer made of a transparent resin on one surface of a transparent base material, and an adhesive layer having a flat surface and a specular antireflection layer are laminated in this order. A method for producing an optical filter having an electromagnetic wave shielding property and an optical mirror surface antireflection property,
A metal pattern layer forming step for forming a metal pattern layer on the transparent substrate, in which the area cut by a virtual plane parallel to the surface of the transparent substrate is a decreasing function S (z) of the distance z from the transparent substrate. When,
After the metal pattern layer forming step, a transfer sheet is prepared by laminating an optical specular antireflection layer and an adhesive layer on a peelable substrate, and the transfer sheet faces the adhesive layer side to the metal pattern layer side. And having an optical mirror surface antireflection layer transfer step of peeling and removing the peelable substrate by overlapping and pressing on the metal pattern layer. A method for producing an optical filter having
(2) The method for producing an optical filter having electromagnetic wave shielding properties and optical specular reflection preventing properties according to (1), wherein the metal of the metal pattern layer is aluminum, and (3) a metal pattern layer made of the aluminum. The electromagnetic wave shielding property and optical specular antireflection property according to (2) above, wherein the thickness of the aluminum oxide film on at least the upper surface (the surface of the aluminum pattern layer far from the transparent substrate) is 0 to 13 mm A method of manufacturing an optical filter, and
(4) On the transparent substrate, a metal pattern layer made of aluminum whose area cut by a virtual plane parallel to the transparent substrate is a decreasing function S (z) of the distance z from the transparent substrate, and transparent An optical material having an electromagnetic wave shielding property and an optical specular antireflection property, in which an adhesive layer made of a resin, in which the unevenness of the metal pattern layer is buried and the surface thereof is flat, and an optical specular antireflection layer are laminated in this order A filter,
An optical filter, wherein the thickness of the aluminum oxide film on at least the upper surface of the metal pattern layer made of aluminum (the surface of the aluminum pattern layer far from the transparent substrate) is 0 to 13 mm,
I will provide a.

According to the present invention, the cross-sectional shape of the metal pattern layer is tapered, that is, the area cut by an imaginary plane parallel to the transparent substrate is a decreasing function S (z) of the distance z from the transparent substrate. Therefore, at the time of transfer of the optical specular antireflection layer, bubbles of the adhesive layer that also serves as a planarizing layer in the recesses (openings) of the metal pattern layer are easily removed, and bubbles are difficult to remain. The manufacturing method can be provided.
Furthermore, when an aluminum pattern layer having an oxide film thickness of 0 to 13 mm at least on the upper surface is formed, zigzag and disconnection of the line outline at the time of chemical etching formation are eliminated, pattern accuracy is improved, and electromagnetic wave shielding ( It is possible to stably obtain the above-mentioned tapered pattern in which variation in surface resistance value) and haze increase can be avoided, and the above-mentioned bubbles hardly remain, and an inexpensive electromagnetic wave shielding filter can be put into practical use.
Further, since the aluminum oxide film can be chemically etched as it is, an additional removal process of the oxide film is not required, and the manufacturing process is not complicated and the cost is increased.
In addition, according to the manufacturing method of the present invention, by providing the adhesive layer having the flat surface with the unevenness of the metal pattern layer and the optical specular reflection preventing layer, it has excellent electromagnetic shielding properties and excellent light An optical filter having specular antireflection properties and particularly suitable for a display can be provided.

FIG. 1A is a conceptual cross-sectional view showing a layer configuration of one form of an optical filter obtained by the manufacturing method of the present invention.
In the case of the figure, the metal pattern layer 2 is formed on one surface of the transparent substrate 1, and the lower surface of the metal pattern layer 2 is adhered and fixed to the transparent substrate 1 by the transparent adhesive layer 4. The transparent adhesive layer 4 is formed on the entire surface of the transparent substrate 1 including the opening of the metal pattern. Note that the adhesive layer 4 is not always essential, and an adhesive layer is not required when a metal thin film is formed on the transparent substrate 1 by vapor deposition or the like and a metal pattern is formed thereon.
The optical filter according to the present invention comprises, on the metal pattern layer 2, an adhesive layer 5 made of a transparent resin, filling the irregularities of the metal pattern and serving as a flattening layer whose surface is a flat surface, and optical specular reflection. The prevention layer 6 is laminated in this order. In FIG. 1, the upper side is the viewer (viewer) side, and the lower side is the image display apparatus side.

FIG. 1B is a conceptual cross-sectional view showing a layer configuration of another embodiment of the optical filter according to the manufacturing method of the present invention.
In the case of the figure, a metal pattern layer 2 made of aluminum (hereinafter sometimes simply referred to as “aluminum pattern layer”) is formed on one surface of the transparent substrate 1, and the aluminum pattern layer 2 is formed on the upper surface thereof. The surface of the aluminum oxide film 3 is provided on the surface (the surface on the side far from the transparent substrate 1) and the lower surface (the surface on the side close to the transparent substrate 1), and the thickness of the oxide film on at least the upper surface is in the range of 0 to 13 mm. It has become. And in the example of the figure, this aluminum pattern layer 2 is bonded and fixed to the transparent substrate 1 by the transparent adhesive layer 4 on the surface of the oxide film 3 on the lower surface side and laminated. The transparent adhesive layer 4 is formed on the entire surface of the transparent substrate 1 including the opening of the aluminum pattern layer.
The optical filter according to the present invention is a flattened layer which is made of a transparent resin on the aluminum pattern layer 2 having the oxide film 3 on at least the upper surface, and the surface of the aluminum pattern layer is filled with a flat surface. The adhesive layer 5 that also serves as the optical mirror reflection preventing layer 6 is laminated in this order. In FIG. 1B, the upper side is the viewer (viewer) side, and the lower side is the image display device side.
Hereinafter, the configuration of the optical filter manufacturing method of the present invention will be described in detail.

[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, such as glass and ceramics. 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 polypropylene and 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, potash glass, borosilicate glass, lead glass, and other transparent ceramics such as PLZT and quartz.

  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. In the case of using a resin or transparent inorganic plate, 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.
The transparent base material may be obtained by performing known easy adhesion treatment such as corona discharge treatment, primer treatment, and ground treatment on the surface.

[Metal pattern layer]
The metal pattern layer 2 is a layer having conductivity, and is a layer responsible for an electromagnetic wave shielding function. Further, even if the metal pattern layer 2 itself is opaque, the presence of openings in the shape of a mesh or the like, It achieves both electromagnetic shielding performance and light transmission.

The shape of the pattern is not particularly limited, and a mesh (network or lattice) shape, a stripe (parallel line group or stripe pattern) shape, a spiral (spiral or spiral) shape, or the like is used. In the mesh shape, the 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, or a circle or an ellipse. The pattern is typically a square, and the pattern has a plurality of openings having these shapes, and the openings are usually line-shaped lines having a uniform width, and usually the openings and the openings. For example, the width W of the line part between the openings is 100 μm or less, preferably 50 μm or less, in view of the aperture ratio and the invisibility of the mesh pattern. is there However, it is preferable to secure at least 5 μm or more to prevent the electromagnetic wave shielding effect and prevent breakage, and the opening width is expressed by (line pitch T− (line width W)). In the present invention, the width is set to 100 μm or more, preferably 150 μm or more, and the above-described line width T and frontage width TW are set such that the aperture ratio = [(TW) × (TW) / (T × T )] × 100% is preferably 60% or more from the viewpoint of light transmittance and the ability of bubbles to hardly remain in the opening during flattening with an adhesive layer, which will be described later. For sexual expression, the maximum is 3000 μm or less and the aperture ratio is 97% or less.
In consideration of the electromagnetic wave shielding function so that the electric resistance value of the metal is not increased and the electromagnetic wave shielding effect is not easily lost, the height of the line portion in the mesh region is preferably 5 μm or more.
On the other hand, in order to perform the etching process without being affected by the side etching, it is more preferable to set the thickness to 15 μm or less.
In addition, the bias angle of the pattern layer region (the angle formed between the mesh line portion and the outer periphery of the electromagnetic wave shielding sheet) 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. .
In addition, the above pattern is a solid pattern in which an opening is not provided for grounding continuity in the periphery of the four sides that does not affect the image display of the electromagnetic wave shielding filter in a display application, or even if the grounding area has a small occupied area ratio May be provided around an internal image display area having an opening.

  As a method for preparing such an electromagnetic wave shielding sheet in which at least a metal pattern layer is laminated, (1) after laminating a transparent substrate and a metal foil with an adhesive, the metal foil is mesh-patterned by a photolithography method. (2) A metal thin film is formed on one surface of a transparent substrate by sputtering or the like to form a conductive treatment layer, and a metal is formed thereon by electrolytic plating. A transparent substrate on which a layer is formed is prepared, and a metal layer and a conductive treatment layer of the metal-plated transparent substrate are meshed by a photolithography method (for example, Japanese Patent No. 3502979, Japanese Patent Application Laid-Open No. 2004-241761). No. gazette).

Among them, in the present invention, in particular, the above (1), that is, after laminating a transparent base material and a metal foil with an adhesive from the point that it can be manufactured with good yield in a short process and at a low cost, It is particularly preferred to use the method of
Then, it demonstrates centering on the method of preparing the electromagnetic wave shielding sheet which has a metal pattern layer which forms the mesh-shaped area | region by the method of said (1).

(Formation of metal pattern layer)
The formation of the metal pattern layer is performed by bonding a conductive metal to the transparent substrate 1 via the transparent adhesive layer 4.
As the conductive metal, it is possible to use a metal such as copper, aluminum, nickel, iron, gold, silver, platinum, tin, stainless steel, tungsten, chromium, titanium, or an alloy in which two or more of these metals are combined. it can. Copper is widely used because of its high conductivity, ease of mesh processing, and cost. Further, in order to further reduce the price, it is desirable to use aluminum.
The metal foil having a thickness of 5 to 15 μm is usually used. If the thickness exceeds 15 μm, it may be difficult to form a fine line width.

(Cross sectional form of metal pattern layer)
In the present invention, the cross-sectional area obtained by cutting the cross-section of each wire rod of the metal pattern layer with a virtual plane P parallel to the surface of the transparent substrate 1 is the reduction function S (z) of the distance z from the transparent substrate 1. It is characterized by a state (hereinafter, sometimes referred to as a “tapered state”). FIG. 2 is an explanatory diagram of the cross-sectional area of the metal pattern layer cut along a virtual plane parallel to the transparent substrate 1. In the present invention, the metal pattern layer 2 after the etching process has a cross-sectional area cut along a virtual plane P parallel to the surface of the transparent base material 1 to a decreasing function S (z) of the distance z from the transparent base material 1. To be. As shown in FIG. 2 (B), the distance z from the transparent substrate 1 is a direction away from the surface of the transparent substrate 1 (upward in FIG. 2 (B)). The distance measured. The cross-sectional area S (z) is compared with the cross-sectional area in the range of the predetermined length y in the line direction of the metal pattern layer 2. Actually, for example, as shown in FIG. 2A, a measurement sample piece 30 cut out from an electromagnetic wave shielding material within a predetermined length y (for example, 50 μm) is embedded in a hardened polishing resin, and FIG. As shown in Fig. 2, the sample is polished so as to be parallel to the transparent substrate 1 after curing, and the cross-sectional area at the virtual plane P is measured by a microscope and evaluated. In the case of FIG. 2B, the width of the cross section perpendicular to the line direction of the metal pattern layer 2 also decreases as the distance z increases, and becomes z = 0, that is, the maximum value W on the lower surface side. The value W is defined as the line width W of the wire flange portion.

  FIG. 3 is a specific example of a cross-sectional shape when a metal pattern layer is formed in the manufacturing method of the present invention. As a cross-sectional shape orthogonal to the line direction of the metal pattern layer 2, as shown in FIG. 3, a trapezoidal quadrangular shape (FIG. 3A), a triangular shape (FIG. 3B), or a trapezoidal shape. Polygons such as pentagons [FIG. 3C]], hexagons [(FIG. 3D)], semi-elliptical shapes [FIG. 3E], parabolic shapes [FIG. 3F], sinusoidal shapes [FIG. 3 (G)], normal distribution curves (not shown), and any one selected from similar shapes can be cited, and each of these shapes is an imaginary parallel to the transparent substrate 1. The cross-sectional area cut by the plane P is a decreasing function S (z) of the distance z from the transparent substrate 1.

For example, in the trapezoid shown in FIG. 3A, the angles of the base side angles α and α ′ are 20 ° to 85 °, and the upper side angles β and β ′ are 95 ° to 160 °. A trapezoid can be illustrated. In addition, the triangle shown in (B) can be exemplified by a triangle having both angles α and α ′ on the base side of 20 ° to 75 ° and an apex angle β image of 30 ° to 140 °. Further, in the pentagon shown in (C), both the angles α, α ′ on the base side are 20 ° to 85 °, the angle β at the top is 30 ° to 170 °, and both angles γ, γ ′ between them are A pentagon having an angle of 105 ° to 170 ° can be exemplified. In addition, in the hexagon shown in (D), the angles of the base-side angles α and α ′ are 20 ° to 85 °, and the angles β and β ′ of the upper-side angles are 95 ° to 160 °. An example is a hexagon having both angles γ and γ ′ of 105 ° to 170 °. In the semi-elliptical shape shown in (E), when the horizontal coordinate of the cross section is x and the vertical coordinate is y, (x ² / a ² ) + (y ² / b ² ) = 1. A semi-elliptical shape represented by the formula can be exemplified. The flatness of the ellipse is about 1/5 ≦ b / a ≦ 5/1 when evaluated by b / a. In addition, in the parabola shown in (F), when the horizontal coordinate of the cross section is assumed to be x and the vertical coordinate is assumed to be y, a parabola represented by the equation y = ax ² can be exemplified. Further, in the sinusoidal shape shown in (G), a curve represented by the equation y = a sin (bx) can be exemplified when the horizontal coordinate of the cross section is x and the vertical seat is y.
Further, the normal distribution curve shape (not shown) is represented by N (μ, σ ² ) in the probability density function expressed by the mathematical formula (1), while the normal distribution of mean μ and variance σ ² is represented by μ = 0. The shape of a standard normal distribution when σ ² = 1, and the shape of a normal distribution curve when μ = 0 and σ ² = 0.2 to 1.0 can be exemplified.

  The present invention is not limited to the specific example of the cross-sectional shape shown in FIG. 3, and may have a cross-sectional shape having other angles. Also, α and α ′, β and β ′, and γ and γ ′ may be the same angle or different angles. When the same angle is used, it is advantageous in terms of the ease of manufacturing the plate and the effect of making the viewing angle uniform. When different angles are used, the angle α, It is advantageous in that peeling can be easily performed by peeling from the side having a smaller angle. In addition to the normal distribution curve, examples of cross-sectional shapes other than those shown in FIG. 3 include a hyperbola, a hyperbolic sine (or hyperbolic cosine) curve, an elliptic function curve, a cycloid curve, a Bessel function curve, etc. Part).

  The metal pattern layer 2 having such a cross-sectional shape is formed when the adherend having the adhesive layer 5 also serving as a planarizing layer is laminated on the metal pattern layer 2 due to the shape characteristics. Between the adhesive layer 5 and the adhesive layer 5 is easy to escape and bubbles are less likely to remain. As a result, the metal pattern layer having the metal pattern layer 2 is bonded to the adherend. However, since the so-called “air fringing” is not generated as much as possible, there is an effect that an optical filter for a display excellent in image transparency can be obtained.

  When the metal pattern layer 2 having such a tapered cross-sectional shape is formed by etching the metal mesh pattern layer by photolithography, the resist film material and thickness, the composition of the etching solution (corrosion solution), It can be formed by controlling the side etching by controlling the concentration, spray pressure, temperature and time.

In the method for producing an optical filter of the present invention, preferably, the metal pattern layer can be a metal pattern layer made of aluminum.
[Metal pattern layer made of aluminum]
The metal pattern layer made of aluminum, that is, the aluminum pattern layer 2 shown in FIG. 1B is a pattern layer formed of aluminum, and the layer itself is opaque, but non-formed portions of the layer such as openings are provided. By using a pattern, the layer achieves both electromagnetic wave shielding performance and light transmittance. The aluminum pattern layer 2 of the present invention has an aluminum oxide film 3 having a specific thickness range of 0 to 13 mm on at least the upper surface thereof. Note that 1Å = 0.1 nm.

  Aluminum in the aluminum pattern layer is mainly composed of aluminum, and may be aluminum alloy in addition to aluminum pure metal, and these are collectively referred to as aluminum in the present invention. Higher is preferable in terms of shielding performance, and aluminum having a purity of 99.0% or more is preferable. Such an aluminum pattern layer using aluminum having a purity of 99.0% or more is a foil conforming to the aluminum foil defined by JIS H4160 (aluminum and aluminum alloy foil) and JIS H4170 (high purity aluminum foil). It can be formed by using

  The aluminum pattern layer is not formed from an aluminum foil, but may be formed from an aluminum vapor deposition film formed on a transparent substrate by vapor deposition, for example, vacuum vapor deposition.

  The thickness of the aluminum pattern layer may be appropriately selected from the viewpoints of electromagnetic wave shielding performance, workability, mechanical strength, and the like, specifically 1 to 100 μm, preferably 5 to 20 μm, and 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.

  The pattern shape and dimensions in plan view of the aluminum pattern layer are as described above, and detailed description is omitted.

(Aluminum pattern layer formation)
In order to form the pattern of the aluminum pattern layer, it is possible to form the pattern by chemical etching after laminating an aluminum layer before pattern formation, such as an aluminum foil, on a transparent substrate.
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.

(Cross sectional shape of aluminum pattern layer)
To make the cross-sectional shape of the aluminum pattern layer tapered, as described above, the material and thickness of the resist film, the composition of the etching solution (corrosion solution), concentration, spray pressure, temperature, and time are adjusted, and the side Etching needs to be controlled. In particular, it is necessary to determine the etching conditions while paying sufficient attention to the thickness of the oxide film described later.

As an etchant for chemically etching the aluminum pattern layer, a known etchant may be appropriately selected and used. For example, an acidic etching solution containing ferric chloride.
The etching is performed including the 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 layer 2.

[Aluminum oxide film]
An aluminum oxide film is a layer containing aluminum oxide, and is usually made of the aluminum oxide alumina (Al ₂ O ₃ ). When the aluminum pattern layer is formed using an aluminum foil, aluminum oxide films are present on both the top and bottom surfaces of the foil, but in the present invention, when the pattern is formed by chemical etching, the side to be etched first That is, the thickness is defined for the upper surface side. The upper limit of the thickness of the aluminum oxide film on at least the upper surface of the aluminum pattern layer is 13 mm, preferably 12 mm, more preferably 10 mm, and still 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 is still present, and copper is changed to inexpensive aluminum. The pattern accuracy failure can be avoided, and the pattern can be processed into a tapered shape with good reproducibility.

  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, but 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 layer is 0 (zero), that is, the oxide film does not have to be present from the viewpoint of not inhibiting the chemical etching.
However, the aluminum oxide film is said to be a passive film, and during the process of processing, transporting and storing the aluminum foil, oxidation or corrosion progresses (inadvertently or undesirably) 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.

  In addition, the aluminum pattern layer in which the aluminum oxide film does not exist on the upper (lower) surface is formed by forming the aluminum layer before pattern formation on the transparent substrate in vacuum and in an inert gas, and forming the aluminum layer before forming the oxide film. This is possible by coating the upper surface of the resin with a resin to block the oxidation reaction. Then, if a predetermined pattern is formed by chemical etching, an aluminum pattern layer having no aluminum oxide film on the upper (lower) surface is obtained.

  There are various ways to reduce the thickness of the aluminum oxide film as described above, but when using aluminum foil for the aluminum pattern layer, the aluminum foil is made by rolling, and then annealed and manufactured. However, it can be adjusted to the target thickness by adjusting the 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 is 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 layer, in the present invention, a specific thickness (thinness) is defined for at least the aluminum oxide film on the upper surface. In addition, the aluminum oxide film on the bottom surface usually has a negligible contribution to the generation of mesh shape burrs during chemical etching compared to the aluminum oxide film on the top surface, so it is not necessary to specify it from the point of pattern accuracy. Absent. However, if the film thickness is too large, the mesh shape due to the aluminum oxide film remaining in the opening may be adversely affected, 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 thickness of the aluminum oxide film on the lower surface is set to 0 to 13 mm as in the upper surface. As one 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 3). A transparent aluminum oxide film having a thickness of 13 Å) can be left to protect the transparent adhesive layer or transparent substrate exposed to the opening during chemical etching 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 treatment layer)
In addition, you may form a blackening process layer in the surface of an aluminum pattern layer.
The blackening treatment layer is a layer for improving external light absorption and image contrast by suppressing light reflection by the aluminum pattern layer and the oxide film on the surface thereof. The blackening treatment layer is provided when external light absorption and image contrast improvement are required. The blackening treatment layer is a layer that reduces the light reflectivity of the aluminum pattern layer by providing it on the surface of the aluminum pattern layer, if there is an oxide film on the surface.

  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 requirements, such as only the upper surface, the upper surface and both side surfaces, only the lower surface, and all surfaces of the upper surface, both side surfaces, and the 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 the lower surface on the image display element side. A blackening treatment layer is preferably formed.

  As the blackening treatment layer, any known electromagnetic shielding filter may be employed 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.

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

  As the transparent adhesive layer, a transparent adhesive may be used as long as it does not impair the light transmission through the opening of the aluminum pattern layer, 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. The polyisocyanate compound is, for example, an aromatic isocyanate compound such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, etc. Examples thereof include aliphatic to alicyclic isocyanate compounds. These isocyanate compounds can also be used in the form of multimers or adducts. A plurality of polyols and polyisocyanate compounds 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 with an adhesive interposed therebetween. The forming method includes a coating method and a printing method.

[Adhesive layer that doubles as a flattening layer]
The metal pattern layer (including the aluminum pattern layer) has an uneven surface (the opening is concave and the wire hook is convex). And, since the material for forming the optical specular antireflection layer is generally poor in performance to fill the unevenness and flatten the surface, when the optical specular antireflection layer is formed directly on the metal pattern layer, When the optical specular antireflection layer does not completely fill the unevenness of the metal pattern layer, the unevenness remaining on the surface of the optical specular antireflection layer scatters image light. Further, even when the optical specular antireflection layer is completely filled with the unevenness of the metal pattern layer, the air in the recesses of the metal pattern layer remains without being sufficiently replaced and becomes bubbles. The image light is scattered to cause the image to become cloudy, and to reduce the image quality such as a decrease in the contrast of the image and a blurring of the outline at the edge of the image. In order to prevent this, an adhesive layer also serving as a planarizing layer is interposed between the metal pattern layer and the optical specular reflection preventing layer.

The adhesive layer also serving as a planarization layer is a layer that fills the unevenness of the metal pattern layer and has a flat surface, and is made of a transparent resin. The resin is appropriately selected from thermoplastic resins, thermosetting resins, ionizing radiation curable resins, and the like.
As the thermoplastic resin, acrylic resin, thermoplastic polyester resin, vinyl chloride-vinyl acetate copolymer, cellulose resin, polyolefin resin, and the like are used.
Here, examples of the acrylic resin include polymethyl (meth) acrylate, polybutyl (meth) acrylate, methyl (meth) acrylate-ethyl (meth) acrylate copolymer, and methyl (meth) acrylate-butyl (meth) acrylate copolymer. Coalesced, methyl (meth) acrylate-styrene copolymer, methyl (meth) acrylate-2hydroxyethyl (meth) acrylate copolymer, methyl (meth) acrylate-2hydroxy 3-phenyloxypropyl (meth) acrylate copolymer, Examples include methyl (meth) acrylate-2hydroxyethyl (meth) acrylate-styrene copolymer (in addition, (meth) acrylate means acrylate or methacrylate).
Examples of the thermoplastic polyester resin include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and 1,4 cyclohexane dimethanol, and many such as terephthalic acid, isophthalic acid, maleic acid, fumaric acid, and adipic acid. Examples include those obtained by condensation polymerization with a basic acid.
Examples of the vinyl chloride-vinyl acetate copolymer include a vinyl chloride-vinyl acetate copolymer having a vinyl acetate content of about 5 to 20% by mass and an average degree of polymerization of about 350 to 900. If necessary, it may further be copolymerized with carboxylic acids such as maleic acid, fumaric acid and (meth) acrylic acid.
Examples of the cellulose resin include nitrocellulose (nitrified cotton), cellulose acetate, and cellulose acetate propionate.
Examples of the polyolefin resin include polyethylene, polypropylene, polymethylpentene, and cyclic polyolefin.
As the thermosetting resin, for example, a thermosetting urethane resin, a thermosetting unsaturated polyester resin, an epoxy resin, or a phenol resin is used.
Here, as the urethane resin, for example, (polyvalent) polyol and (polyvalent) isocyanate are reacted. Examples of the (polyvalent) polyol include acrylic polyol, polyester polyol, polyether polyol, polyurethane polyol and the like. (Polyvalent) isocyanates include 2,4 tolylene diisocyanate, xylene diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate and other aromatic isocyanates, 1,6 hexamethylene diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate aliphatic (or fat Cyclic) isocyanates.
As the ionizing radiation curable resin, a monomer (monomer) that is polymerized and cured by a reaction such as crosslinking with ionizing radiation, or a prepolymer or an oligomer is used. As the monomer, for example, a radical polymerizable monomer, specifically, 2-ethylhexyl (meth) acrylate, diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) Examples thereof include various (meth) acrylates such as acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. Examples of the prepolymer (or oligomer) include radically polymerizable prepolymers, specifically, urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, triazine (meth) acrylate, and the like. (Meth) acrylate prepolymers, polythiol prepolymers such as trimethylolpropane trithioglycolate, pentaerythritol tetrathioglycolate, and unsaturated polyester prepolymers. Other examples include cationically polymerizable prepolymers such as novolac epoxy resin prepolymers and aromatic vinyl ether resin prepolymers.
These monomers or prepolymers may be used alone or in combination of two or more types of monomers, two or more types of prepolymers, or one type of monomer, depending on the required performance, coating suitability, etc. A mixture of the above and one or more prepolymers can be used.
As the photopolymerization initiator, in the case of a radically polymerizable monomer or prepolymer, a benzophenone-based, acetophenone-based, thioxanthone-based, benzoin-based compound, etc., or in the case of a cationic polymerization-based monomer or prepolymer, , Metallocene-based, aromatic sulfonium-based and aromatic iodonium-based compounds are used. These photopolymerization initiators are added in an amount of about 0.1 to 5 parts by weight with respect to 100 parts by weight of the composition comprising the monomer and / or prepolymer.
The ionizing radiation is typically ultraviolet rays or electron beams, but in addition, electromagnetic waves such as visible rays, X rays and γ rays, or charged particle rays such as α rays and various ion rays are used. You can also.

  In the constituent material of the adhesive layer also serving as the flattening layer, an additive can be appropriately added as necessary. Examples of the additive include a heat stabilizer, a radical scavenger, a plasticizer, a surfactant, an antistatic agent, an antioxidant, an ultraviolet absorber, an infrared absorber, a dye (colored dye, colored pigment), and an extender pigment. And a light diffusing agent.

  The thickness of the adhesive layer also serving as a flattening layer is the thickness of the metal pattern layer, which is the maximum thickness, in order to fill the unevenness of the metal pattern layer and make the surface flat. More preferably, the thickness is set to be about 1 to 20 μm thicker than the thickness of the metal pattern layer.

(Method of forming an adhesive layer that also serves as a flattening layer)
Flattening layer in the present invention, to form an adhesive layer serving as a planarizing layer on the uneven surface of the metal pattern layer. As a forming method, a liquid composition capable of forming the adhesive is directly applied on a metallized pattern layer, and then the composition is solidified, or the adhesive layer formed in advance is transferred. To form. In the case of the transfer method, a transfer sheet having a configuration in which an adhesive layer serving also as a flattening layer as a transfer layer is formed on a release substrate in advance is prepared. Next, the transfer sheet is pressure-bonded onto the metal pattern layer in such a direction that the surface on the adhesive layer side of the transfer sheet is in contact with the metal pattern layer side. If the adhesive layer has fluidity at that time, it remains in that state, and if the adhesive layer does not have fluidity at that time, the flat adhesive layer is heated to soften or Fluidize by a method such as melting. Next, the fluid adhesive layer is filled into the irregularities of the metal pattern layer to replace the air in the irregularities. During this process, the side surface opposite to the metal pattern side of the adhesive layer is in contact with the flat surface of the release substrate and the deformation is restricted, so that the flat surface is maintained. Thereafter, the adhesive layer is left on the metal pattern layer side, and only the peeling substrate is peeled off.
In this transfer mode, an optical mirror surface antireflection layer is also formed on the release substrate as a transfer layer; an adhesive layer that also serves as a release substrate / optical mirror surface antireflection layer / flattening layer. If it is used as a transfer sheet, an optical specular antireflection layer can be formed on the metal pattern layer simultaneously with the flattening layer made of an adhesive. In this transfer mode, the adhesive layer has a function of bonding the transfer layer to the transfer target and a function of a flattening layer for flattening the metal pattern layer.

[Optical mirror antireflection layer]
One of the following antiglare layers or antireflection layers is selected. Alternatively, both can be provided in combination.

(Anti-glare layer)
An anti-glare layer (Anti Glare layer, abbreviated as AG layer) is used to roughen the light incident surface or disperse light diffusing particles in the layer in order to scatter or diffuse extraneous light. It will be. For this roughening treatment, a method of forming a rough surface directly on the surface of the layer by a sandblasting method or an embossing method to roughen the surface; a light diffusion in a resin binder cured by radiation or heat or a combination thereof To provide a coating film having a rough surface with a coating film in which fine irregularities corresponding to the filler are projected on the coating film surface containing inorganic filler such as silica or organic filler such as resin particles as conductive particles And a method of forming a porous film having a sea-island structure on the surface of the coating film. As the resin of the resin binder, a curable acrylic resin, an ionizing radiation curable resin, or the like is preferably used in the same manner as the hard coat layer described below because surface strength is desired as the surface layer.
In the case where the light diffusing particles are dispersed in the layer, a refractive index difference (preferably 0.14 or more) is provided between the filler dispersed in the coating and the coating binder resin. Select materials to have. In the case of this form, the coating surface may be a flat surface (smooth surface).
The thickness of the antiglare layer is not particularly limited, but is preferably 0.07 μm or more and 20 μm or less.
Further, when the average interval between the irregularities of the antiglare layer is Sm, the average inclination angle of the irregularities is θa, and the ten-point average roughness of the irregularities is Rz, Sm is 60 to 250 μm and θa is 0 It is preferable that the angle is 3 ° to 1.0 ° and Rz is 0.3 to 1.0 μm.
In addition, said Sm, (theta) a, and Rz are based on JISB06011994, for example, can be measured with a surface roughness measuring device ["SE-3400" by Kosaka Laboratory Ltd.].

(Antireflection layer)
The antireflection layer (Anti Reflection layer, abbreviated as AR layer) is a single layer of a low refractive index layer, or a low refractive index layer and a high refractive index layer, and the low refractive index layer is positioned in the uppermost layer. A multilayer structure in which the layers are alternately laminated is generally used, and can be formed by a dry film formation method such as vapor deposition or sputtering, or by using a wet film formation method such as coating.
Here, the high (low) refractive index layer means that the refractive index of the layer is relatively high compared to a layer adjacent to the layer (for example, a planarization layer or a low (high) refractive index layer) ( Means low).
When the antireflection layer is further provided with an abrasion resistance function, it is formed by appropriately using a material having high hardness as described in the section of the following abrasion resistance function (hard coat) layer.

In order to improve the antireflection effect, in principle, the refractive index of the low refractive index layer is preferably set to the square root of the refractive index of the layer immediately below. For example, if the layer immediately below has a refractive index of 1.50, the refractive index of the low refractive index layer is 1.23, and if the layer directly below has a refractive index of 2.10, the refractive index of the low refractive index layer is 1.45. It is. Even if this value cannot be completely matched, it is designed to be as close to this value as possible.
Examples of the material having such a low refractive index include LiF (refractive index n = 1.36), MgF ₂ (refractive index n = 1.38), 3NaF · AlF ₃ (refractive index n = 1.4), AlF ₃ ( Refractive index n = 1.37), Na ₃ AlF ₆ (refractive index n = 1.33), NaF (refractive index n = 1.33), CaF ₂ (refractive index n = 1.44), Na ₃ AlF ₆ (Refractive index n = 1.33), inorganic materials such as SiO ₂ (refractive index n = 1.45), or inorganic low reflection in which these inorganic materials are finely divided and contained in an acrylic resin or an epoxy resin Examples thereof include organic low-reflective materials such as materials, fluorine-based and silicone-based organic compounds, and other low refractive index thermoplastic resins, thermosetting resins, and radiation curable resins.

  Further, fine particles having voids may be used for the low refractive index layer. The fine particles having voids form a structure in which fine particles are filled with gas and / or a porous structure containing gas, and are in inverse proportion to the gas occupancy ratio in the fine particles compared to the original refractive index of the fine particles. It means fine particles having a reduced refractive index. The present invention also includes fine particles capable of forming a nanoporous structure inside and / or at least part of the surface depending on the form, structure, aggregation state, and dispersion state of the fine particles inside the coating film. It is. The fine particles having voids may be either inorganic or organic, and include, for example, those made of metal, metal oxide, and resin, and preferably silicon oxide (silica) fine particles.

Furthermore, a material obtained by mixing a sol obtained by dispersing ultrafine silica particles of 5 to 30 nm in water or an organic solvent and a fluororesin-based or silicon-based film forming agent can be used. The sol in which the ultrafine silica particles of 5 to 30 nm are dispersed in water or an organic solvent is obtained by a method of dealkalizing alkali metal ions in alkali silicate salt by ion exchange or the like, or neutralizing alkali silicate salt with mineral acid. A known silica sol obtained by condensing active silicic acid known by the method, etc., a known silica sol obtained by condensing alkoxysilane with hydrolysis in an organic solvent in the presence of a basic catalyst, and the above-mentioned An organic solvent-based silica sol (organosilica sol) obtained by substituting water in the aqueous silica sol with an organic solvent by a distillation method or the like is used. These silica sols can be used in both aqueous and organic solvent systems. In producing the organic solvent-based silica sol, it is not necessary to completely replace water with the organic solvent. The silica sol contains solids 0.5 to 50 wt% concentration as SiO _2. Various structures such as a spherical shape, a needle shape, and a plate shape can be used for the structure of the ultrafine silica particles in the silica sol. As the film forming agent, alkoxysilane, metal alkoxide, hydrolyzate of metal salt, or fluorine-modified polysiloxane can be used. According to a preferred embodiment of the low refractive index layer, “fine particles having voids” are preferably used.

  The low-refractive index layer is formed by diluting the above-mentioned materials in, for example, a solvent, and using a wet coating method such as spin coating, roll coating, printing, etc. In the case of forming a specular antireflection layer in the case of (1), after being provided on a predetermined layer and dried, it is obtained by curing with heat or radiation (in the case of ultraviolet rays, the above-mentioned photopolymerization initiator is used) or the like. it can. Alternatively, the low refractive index layer can be provided by a vapor phase method (or dry coating method) such as vacuum deposition, sputtering, plasma CVD, or ion plating.

As a material used for the high refractive index layer, either an inorganic material or an organic material such as a resin can be used. As for the high refractive index resin, any resin can be used as long as it is a transparent material having a refractive index relatively lower than that of the low refractive index layer. Thermosetting resin, thermoplastic resin, ionizing radiation ( A curable resin (including ultraviolet rays) can be used. Thermosetting resins include phenolic resin, melamine resin, polyurethane resin, urea resin, diallyl phthalate resin, guanamine resin, unsaturated polyester resin, amino alkyd resin, melamine-urea cocondensation resin, silicon resin, polysiloxane resin, etc. A curing agent such as a crosslinking agent and a polymerization initiator, a polymerization accelerator, a solvent, a viscosity modifier and the like can be added to these resins as necessary.
As an inorganic material having a high refractive index, for example, ZnO (refractive index n = 1.9), TiO ₂ (refractive index n = 2.3 to 2.7), which can also obtain an ultraviolet shielding effect, CeO ₂ (refractive index n = 1.95), can also be antistatic effect to prevent adhesion of dust are granted, SnO ₂ (refractive index n = 1.95) doped with antimony or ITO ( Cs _0.33 WO ₃ (cesium-containing tungsten oxide (refractive index n = 2.5 to 2.6), which can also obtain an effect of shielding near infrared rays, with a refractive index n = 1.95). Al ₂ O ₃ (refractive index n = 1.63), La ₂ O ₃ (refractive index n = 1.95), ZrO ₂ (refractive index n = 2.05), Y ₂ O ₃ (refractive index n = 1.87), etc. When these inorganic materials are used as fine particles, they are used alone. Are mixed and used in a colloidal form dispersed in an organic solvent or water in terms of dispersibility. The particle size is preferably 1 to 100 nm, and preferably 5 from the transparency of the coating film. The high refractive index layer can also be formed by applying a coating composition in which ultrafine particles having a high refractive index are added to a binder resin. The refractive index of is preferably in the range of 1.55 to 2.70.

In order to provide a high refractive index layer, for example, the high refractive index inorganic material described above is made into fine particles, dispersed in a binder resin and diluted in a solvent, and then wet coating such as spin coating, roll coating, printing, etc. After being provided on the substrate and dried, it may be cured by heat or radiation (in the case of ultraviolet rays, the above-mentioned photopolymerization initiator is used). Alternatively, the high refractive index layer can be provided by depositing and forming the above-described high refractive index inorganic material by a vapor phase method (or dry coating method) such as vacuum deposition, sputtering, plasma CVD, or ion plating.
The thickness of the low refractive index layer is not particularly limited. Usually, the product of the refractive index and the thickness of the low refractive index layer is the wavelength of visible light (specific wavelength in the range of 380 nm to 780 nm) whose reflectance should be minimized. About 1/4 (95 to 195 nm).

(Abrasion resistant functional layer)
The scratch-resistant (hard coat) layer preferably exhibits a hardness of “H” or higher in a pencil hardness test specified by JIS K5600-5-4 (1999). Resin) The material is not particularly limited as long as the same transparency as that of the substrate can be realized.
The scratch-resistant (hard coat) layer is usually formed as a cured resin layer. As the position and form to be formed, either one of the constituent layers of the optical specular antireflection layer is used, or it is formed as an independent separate layer between the optical specular antireflection layer and the flattening layer.
As the curable resin to be used, an ionizing radiation curable resin, other known curable resins, or the like may be appropriately employed according to required performance. Examples of the ionizing radiation curable resin include acrylate-based, oxetane-based, and silicone-based resins. For example, acrylate-based ionizing radiation curable resins are, for example, polyfunctional (meth) acrylate prepolymers such as polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, or trimethylolpropane tri (meth) ) Trifunctional or higher polyfunctional (meth) acrylate monomers such as acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc., alone or in combination of two or more selected from these It can be formed as a coating film using an ionizing radiation curable resin.
The scratch-resistant function (hard coat) is obtained by diluting the above-mentioned material with a solvent as necessary, on the flattening layer, or on the transfer sheet particularly when an optical specular antireflection layer is formed by a transfer method described later. It can be formed on the optical mirror surface antireflection layer by a wet film forming method such as coating.
The thickness of the scratch-resistant functional layer is not particularly limited, but is preferably 1.0 μm or more and 20 μm or less, more preferably 3.0 μm or more and 5 μm or less.

[Method of forming optical mirror antireflection layer]
In order to form an optical specular antireflection layer on the adhesive layer that also serves as a planarization layer, a transfer method in which the optical specular reflection prevention layer is transferred from the transfer sheet through the planarization layer, optical specular reflection prevention A method of directly applying a layer-forming paint or a method of adhering and laminating a sheet having a preliminarily formed optical specular antireflection layer on the surface can be employed. However, the transfer method is preferable in that the unevenness of the light reflectance is small and the thickness and the number of layer structures are small. Thus, it is possible to obtain a filter with an optical specular reflection preventing layer in which the adhesive layer also serving as a planarizing layer is embedded in the unevenness of the metal pattern layer.

(Transfer sheet)
In the present invention, a transfer sheet is used in which at least an optical specular antireflection layer is peelably laminated as a transfer layer on a peelable substrate. More preferably, a transfer sheet having an adhesive layer that also serves as a planarizing layer in addition to the optical specular antireflection layer is used as the transfer layer. Hereinafter, a transfer sheet mainly including both the optical specular reflection preventing layer and the adhesive layer will be described as an example (however, the present invention is not limited to this embodiment).
(Peelable substrate)
It consists of an appropriate base material sheet. If necessary, it is preferable to form a release layer on the transfer layer side in order to ensure releasability (also referred to as releasability) from the transfer layer.
As the substrate sheet, a sheet having high strength and dimensional stability (elastic modulus) with respect to stress, heat resistance (especially when heating during transfer), and high surface smoothness is selected. A resin sheet having a thickness of about 20 to 100 μm or a paper having a basis weight of 20 to 100 g / m ² is used. Examples of the resin include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and polyolefin resins 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 base sheet itself has insufficient peelability from the optical specular reflection preventing layer (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.

(Transfer layer)
It is a layer transferred from the peelable substrate side to the metal pattern layer side. It consists of at least an optical specular antireflection layer, and further contains an adhesive layer and other transfer layers as necessary.
The adhesive layer as one element of the transfer layer is made of a material having adhesiveness to both the optical specular antireflection layer and the metal pattern layer.
Examples of the material for the adhesive layer include, as a thermoplastic resin, an acrylic resin, a vinyl chloride-vinyl acetate copolymer, a thermoplastic polyester resin, and the like selected from those exemplified as the adhesive layer that also serves as a planarizing layer. Can be used. In addition, thermosetting resins or ionizing radiation curable resins can also be used.
The thickness of the adhesive layer is usually not less than the height of the metal pattern layer, and is generally about 1 to 30 μm.
In addition, the formation form of an adhesive bond layer forms the adhesive bond layer (flattening layer and adhesive layer combined layer) which can function also as a planarization layer as a transfer layer previously on a transfer sheet. On the other hand, no planarization layer is formed on the metal pattern layer. In this state, the adhesive layer is transferred from the transfer sheet onto the conductive pattern layer. At the time of bonding, the adhesive layer is given fluidity by heating or the like, and the adhesive layer is filled in the unevenness of the conductive pattern layer, and the surface of the adhesive layer is flattened, and then the adhesive layer Solidify. Thus, the formation of the planarizing layer is completed simultaneously with the formation of the adhesive layer on the conductive pattern layer. Even in this form, if both the adhesive layer and the flattening layer combined layer and the optical specular antireflection layer are formed as a transfer layer on the transfer sheet, the flattening layer is formed in one transfer step. The formation of the adhesive layer and the formation of the optical specular reflection preventing layer can be performed simultaneously.
The other transfer layer provided as necessary is, for example, a layer containing a near-infrared absorbing agent, an ultraviolet absorbing agent, a neon light absorbing agent, various coloring dyes, an antistatic agent, etc. in a resin as appropriate. Functions as an infrared absorbing layer.

  Such a transfer sheet can be in the form of a single sheet cut into a desired size or shape, or in the form of a continuous band wound up by winding.

  The optical filter obtained by the production method of the present invention can be used for various applications. In particular, television receivers, display units for various measuring instruments and instruments, display units for various office equipment and computer equipment, plasma displays (PDP), cathode ray tube displays (CRT), liquid crystal displays (LCDs) used in telephones, etc. It is suitable for a front filter of an image display device such as, and particularly suitable for a plasma display. In addition, it can also be used for applications such as windows for buildings and windows for microwave ovens.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples.

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 layer. 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 photolithographic method, and 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 layer having a grounding region with no opening was formed.
The etching process corresponds to the mesh opening after applying a photosensitive etching resist on the entire surface of the aluminum foil of the aluminum foil laminate sheet, exposing the desired mesh pattern, developing, hardening, and baking. After forming a resist pattern in which the resist layer is not formed on the area to be etched, the aluminum foil in the resist layer non-formed part is removed by etching by immersing it in an acidic aqueous etchant containing ferric chloride. Then, an aluminum pattern layer having a mesh-shaped opening was formed, and then water washing, resist peeling, washing, and drying were sequentially performed.
The mesh shape of the mesh area (image display area) is such that the opening in plan view has a square shape, and the line width of the linear line portion that is a non-opening portion is 20 μm, and the line interval (pitch) is 300 μm. The height of the part is 12 μm, and the cross-sectional area cut by a virtual plane P parallel to the surface of the transparent substrate is a decreasing function S (z) of the distance z from the surface. More specifically, the trapezoidal shape is shown in FIG. 3A, where α is 75 °, α ′ is 75 °, β is 105 °, and β ′ is 105 °. When the sheet was cut into a rectangular sheet, 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 intermediate of electromagnetic shielding filter is continuously supplied to the blackening device by roll-to-roll, forming a nickel compound blackening treatment layer on the aluminum pattern layer surface of the intermediate And wound up to obtain an electromagnetic wave shielding filter.
As for the pattern accuracy of the obtained aluminum pattern layer, the variation in the line width of the mesh wire ridge is 4.5 μm, and the surface unevenness is indistinguishable in appearance and there is no problem, and there is no disconnection of the wire ridge, as described below. There was no decrease in electromagnetic shielding properties due to a decrease in surface resistance.

(Preparation of transfer sheet including optical mirror antireflection layer and adhesive layer)
Preparation of peelable substrate:
A long biaxially stretched polyethylene terephthalate (PET) film having a width of 1000 mm and a thickness of 100 μm having a melamine resin release layer formed on one side was prepared.
Formation of transfer layer:
On the release layer of this polyethylene terephthalate film, an optical specular antireflection layer was formed. As a composition for forming a low refractive index layer constituting the antireflection layer, 1.95 parts by mass of pentaerythritol triacrylate (PETA), 1-hydroxy-cyclohexyl-phenyl-ketone [Ciba Specialty as a photopolymerization initiator, -0.1 part by mass, trade name “Irgacure 184” manufactured by Chemicals Co., Ltd., and then treated silica sol-containing solution [fine particles having voids (average particle size 60 nm), silica sol solid content 20% by mass, solvent; methyl isobutyl ketone ] 12.3 parts by mass and a solution containing silica particles [manufactured by Nacalai Tesque, trade name “sicical”, giant particles (average particle size 100 nm), solid content of silica particles 20% by mass, solvent: methyl isobutyl ketone] 1.23 After mixing parts by mass, add 83.5 parts by mass of methyl isobutyl ketone, A coating solution for forming a low refractive index layer in the form of a curable resin composition was prepared.
Release layer of the PET film The coating solution for forming a low refractive index layer was applied with a dry weight of 0.1 g / m ² (bar coating) and then dried at 40 ° C. for 60 seconds. Thereafter, using a UV irradiation device made of high-pressure mercury vapor, the film was cured by UV irradiation at an irradiation dose of 200 mJ / cm ² to form a low refractive index layer, and an antireflection layer was continuously formed.
The film thickness after curing of the low refractive index layer was 90 nm and the refractive index was 1.44.
Next, 100 parts by mass of a mixed composition of a urethane acrylate prepolymer and 1,6 hexanediol diacrylate monomer, 5 parts by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator, and 300 parts of methyl cellosolve are formed on the optical mirror antireflection layer. A mass part was mixed and a uniform coating agent was applied by a roll coater method, dried at 80 ° C., and then irradiated with an 80 W high-pressure mercury lamp to form a hard coat layer having a thickness of about 3 μm.
A solution comprising 10 parts by weight of a thermoplastic polyester resin, 40 parts by weight of toluene, and 50 parts by weight of methyl ethyl ketone is continuously applied at a rate of 50 m / min by a reverse roll coating method on the hard coat layer of the optical specular antireflection layer and dried. Then, an adhesive layer having a thickness of 25 μm was formed to obtain a transfer sheet (hereinafter, also simply referred to as “antireflection transfer sheet”) including an optical mirror antireflection layer and an adhesive layer.

(Transfer of adhesive layer and optical specular antireflection layer on aluminum pattern layer)
The antireflection transfer sheet thus obtained was transferred onto the aluminum pattern layer by a thermal transfer method. As the thermal transfer step, first, a commercially available hot stamp transfer machine is prepared, the electromagnetic wave shielding filter is placed on the substrate mounting table of the transfer machine, and the reflection is further reflected on the aluminum pattern layer of the electromagnetic wave shielding filter. The transfer sheet for prevention was placed with its adhesive layer side facing. Next, in the transfer machine, a roller whose surface of an iron shaft core is coated with silicon rubber is heated to a surface temperature of 170 ° C. The transfer sheet described above is rotated while rotating the roller around the shaft core. While pressing the peelable substrate side with a pressure (set value) of 1 g / cm 2, the feed rate of the mounting table was sent at 1 m / min. After that, the transfer sheet surface (peelable substrate side) was cooled to room temperature (23 ° C.), and the polyethylene terephthalate film was peeled off together with the release layer to complete the transfer process. Thus, an optical filter composed of an aluminum pattern layer with an optical specular antireflection layer was produced.
In the aluminum pattern layer with the antireflection layer produced in this way, no air bubbles formed by enclosing air during thermal transfer were found.
Example 2
As an aluminum foil, an optical filter of Example 2 was obtained in the same manner as in Example 1 except that an oxide film having a thickness of 13 mm on the upper and lower surfaces was used.

Comparative Example 1
Except for changing the etching conditions, the mesh shape of the mesh area (image display area) is the same as in the embodiment, and the line shape is a linear line portion where the shape of the opening in a plan view is a square and a non-opening portion. The line width is 20 μm, the line interval (pitch) is 300 μm, the height of the line part is 12 μm, and the cross-sectional area cut by a virtual plane P parallel to the surface of the transparent substrate increases the distance z from the surface. More specifically, the function is S (z), and more specifically, the inverted trapezoidal shape shown in FIG. 4, where α is 90 °, α ′ is 90 °, β is 90 °, and β ′ is 90 °. An aluminum pattern layer having a simple cross section was produced. In addition, the control of the cross-sectional shape according to the etching conditions changed the concentration and temperature of the etching solution as compared with the example, and sprayed the etching solution while rotating the aluminum foil laminated sheet.
Next, in the same manner as in the example, an optical filter composed of an aluminum pattern layer with an optical mirror surface antireflection layer was produced.
In the obtained filter, bubbles were observed between the aluminum pattern layer and the adhesive layer bonded on the aluminum pattern layer with the antireflection layer after the thermal transfer treatment.

Comparative Example 2
As an aluminum foil, an optical filter of Comparative Example 2 was obtained in the same manner as in Example 1 except that an oxide film having a thickness of 15 mm on the upper and lower surfaces was used.
As for the pattern accuracy of the obtained aluminum pattern layer, the variation in the line width of the mesh wire ridge was 20 μm, and the surface unevenness was distinguishable in appearance. In addition, disconnection of the wire rod part was also observed in part.

[Evaluation]
(Transparency evaluation)
When the optical filters of the example and the comparative example were compared by visual observation, the white turbidity was not recognized in the openings in the examples 1, 2 and 2, but the comparative example 1 In white turbidity was observed. The transparency as a filter was lowered, and the antireflection effect was insufficient.
(Evaluation of electromagnetic shielding properties)
In an anechoic chamber compliant with the VCCI 3m method, vertical polarization and horizontal polarization were measured in the range of 30 MHz to 1000 MHz. The produced optical filter was placed on a turntable with a height of 80 cm. A dipole antenna was used as the antenna, and the measurement was performed at a height of 1 m for vertical polarization, and at a height of 2 m for horizontal polarization.
Regarding the optical filters according to Example 1, Example 2, and Comparative Example 1, the standard value of VCCI class B could be stably satisfied in the entire measurement range. About the display which concerns on the comparative example 2, the standard value of the class B of VCCI cannot be satisfy | filled in all the measurement ranges, and electromagnetic wave shielding performance was not stabilized.

It is typical sectional drawing which shows an example of the optical filter of this invention. It is explanatory drawing of the cross-sectional area of the metal pattern layer cut | disconnected by the virtual surface parallel to a transparent base material. It is a schematic diagram of the specific example of the cross-sectional shape of the wire hook part of the metal pattern layer in this invention. It is a schematic diagram of the cross-sectional shape of the wire hook part of the metal pattern layer by a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base material 2 Metal pattern layer, metal pattern layer which consists of aluminum 3 Oxide film of aluminum 4 Transparent adhesive layer 5 Adhesive layer which also serves as a planarization layer 6 Optical mirror surface antireflection layer

Claims (4)

A metal pattern layer and a transparent resin are formed on one surface of the transparent base material, and the metal pattern layer is filled with the unevenness of the metal pattern layer, and the adhesive layer having a flat surface and the optical specular antireflection layer are laminated in this order. A method for producing an optical filter having electromagnetic wave shielding properties and optical mirror surface antireflection properties,
A metal pattern layer forming step for forming a metal pattern layer on the transparent substrate, in which the area cut by a virtual plane parallel to the surface of the transparent substrate is a decreasing function S (z) of the distance z from the transparent substrate. When,
After the metal pattern layer forming step, a transfer sheet is prepared by laminating an optical specular antireflection layer and an adhesive layer on a peelable substrate, and the transfer sheet faces the adhesive layer side to the metal pattern layer side. And an optical specular antireflection layer transfer step for peeling and removing the releasable substrate by overlapping and pressing on the metal pattern layer. The manufacturing method of the optical filter which has these.   The manufacturing method of the optical filter which has the electromagnetic wave shielding property of Claim 1, and optical specular reflection prevention property of Claim 1 whose metal of the said metal pattern layer is aluminum.   The electromagnetic wave shielding property and light according to claim 2, wherein the thickness of the aluminum oxide film on at least the upper surface of the metal pattern layer made of aluminum (the surface of the aluminum pattern layer far from the transparent substrate) is 0 to 13 mm. A method for producing an optical filter having specular antireflection properties. On the transparent substrate, a metal pattern layer made of aluminum whose area cut by a virtual plane parallel to the transparent substrate is a decreasing function S (z) of the distance z from the transparent substrate, and a transparent resin An optical filter having an electromagnetic wave shielding property and an optical specular antireflection property, in which an unevenness of the metal pattern layer is filled and an adhesive layer having a flat surface and an optical specular antireflection layer are laminated in this order. And
An optical filter, wherein the thickness of the aluminum oxide film on at least the upper surface (the surface of the aluminum pattern layer far from the transparent substrate) of the metal pattern layer made of aluminum is 0 to 13 mm.

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