JP2011013628A - Optical filter and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter for an image display device, the optical filter having high contrast under the presence of external light and near infrared absorbance.SOLUTION: The optical filter 100 includes an image contrast-improving filter 30 and a near infrared absorption layer 90, and optionally includes a front surface film 40 and an electromagnetic wave shield film 50. The filter 30 includes: dark color parts 10 that are formed on one surface S1 of a transparent substrate 4, are linear and arranged in parallel in the in-plane direction, and have a trapezoidal cross-sectional shape in a direction orthogonal to the extension direction thereof; and a light-transmitting area 20 between the adjacent dark color parts. The dark color part 10 is made by filling dark color particles 1 and a transparent resin 2 in a groove-like recessed part 3. In the light-transmitting area 20, a surface of the transparent substrate 4 is covered with a transparent protective layer 2L made of the transparent resin 2. The relation of t<dmin<dmax<W and t<dmin<dmax<H is satisfied among the minimum particle size dmin and the maximum particle size dmax of the dark color particles 1, the thickness t of the transparent protective layer 2L, and the maximum width W and the depth H of the groove-like recessed part 3.

Description

  The present invention relates to various image display devices (displays), and more particularly to an optical filter suitable for being arranged on a display surface of a plasma display, and an image display device including the optical filter.

  In image display devices such as a plasma display, a liquid crystal display, a cathode ray tube display, and an electroluminescent display, studies have been made to improve the image quality.

  In particular, as an example of improving the image quality by providing a functional member on the display surface side of the image display device, for example, Patent Document 1 discloses a mesh film in which strands are knitted and crossed vertically and horizontally to prevent image flickering. It has been proposed to arrange on the display surface. This reticulated film is thought to be effective in preventing flickering of the image, but when external light such as sunlight or electric light (also referred to as extraneous light) is incident on the screen, the image contrast is lowered. There is. For such a problem, for example, it is conceivable to use a black fiber having light absorption performance as the strand. However, external light is incident from an oblique direction of the screen, while image light is emitted in a direction orthogonal to the screen, so that only the external light is absorbed with high efficiency without improving the image contrast. In order to achieve this, external light incident from an oblique direction of the screen is increased by increasing the length of the black fiber in the depth direction (that is, the direction connecting the image display device and the viewer, in other words, the orthogonal direction of the screen). Must be received over a large area. However, in order to increase the length of the fiber in the depth direction, it is necessary to increase the fiber diameter, and as a result, the width (direction parallel to the screen) is inevitably increased and the image light transmitted to the viewer side is increased. The problem of being disturbed by black fibers arises.

  For example, Patent Document 2 proposes a micromesh type antireflection filter for preventing reflection on the screen of a color cathode ray tube display. This antireflection filter is made of a micromesh in which nylon single fibers are plain-woven into a mesh shape, and the micromesh is in a constant pitch range with respect to the horizontal pitch and vertical pitch of the dot pitch of the fluorescent film, and The micromesh weft is in a certain angle range with respect to the horizontal scanning line. Such an antireflection filter is considered to be effective in preventing the occurrence of moire, but the problem that the image contrast is lowered when external light such as sunlight or electric light enters the screen cannot be solved.

  In order to solve the problem of improving the image contrast, for example, in Patent Document 3, as a contrast improving layer constituting a front filter for a plasma display to be bonded to a screen, it is connected in a straight line in a predetermined direction along the surface direction of the layer. The cross section perpendicular to the extending direction has a trapezoidal shape with the wide bottom base facing the viewer side, and is linear in a direction parallel to the lens portion that transmits light and the lens portion. The cross-section perpendicular to the extending direction has a wedge shape with the wide lower base facing the display surface side of the plasma display, and a number of light absorbing parts that absorb light alternately mesh with each other. It proposes what is arranged. This front filter is intended to improve image contrast in a mode that also has an electromagnetic wave shielding function.

Japanese Patent Publication No.34-8069 JP-A-62-136741 JP 2007-272161 A JP 2006-154516 A

  The front filter proposed in Patent Document 3 has insufficient points for further practical use and higher quality, and the solution is required. That is, the front filter proposed in Patent Document 3 has a light-absorbing portion formed by filling a wedge-shaped groove with a paint made of dark resin, and the light-absorbing portion has a wedge-shaped groove portion arranged in parallel. It is formed by applying a paint made of dark resin on the surface, and then scraping with a doctor blade or the like. However, when scraping with a doctor blade or the like, dark resin remains in the translucent region (appears as a convex portion with respect to the groove-shaped recess) which is the surface of the transparent base other than the groove, and the translucent property There is a drawback that the light transmittance of the region is lowered and the display image becomes dark. The reason why the dark resin remains in the translucent area is that the flatness of the translucent area is incomplete unlike flat rigid bodies such as glass plates and metal plates, and it is deformed by pressing a doctor blade or the like. This is due to the fact that it is impossible to scrape completely due to, for example, bending and the dark resin paint being liquid and oozing into even a small gap.

  Although it is possible to wipe or polish the dark paint remaining in the translucent area with a cloth soaked with an organic solvent, the number of steps is increased and the translucent area is added with the organic solvent. May become cloudy due to swelling / elution, or scratches may accompany the polishing, and the display image may become cloudy due to these factors.

  On the other hand, various image display devices, especially plasma displays, in principle, emit near infrared rays from their display surfaces. In particular, near infrared rays in the wavelength range of 800 to 1100 nm are known to cause malfunctions in the remote control of home appliances. For example, Patent Document 4 proposes a near infrared absorption filter provided on the display surface of a plasma display. (Patent Document 4).

  However, there has been no optical filter that can absorb near infrared rays and realize high contrast on the display surface of the plasma display.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical filter for an image display device having high contrast and near-infrared absorption ability in the presence of external light. Another object of the present invention is to provide an image display device having such an optical filter on a display surface.

An optical filter according to the present invention for solving the above-mentioned problems is a linear cross-section orthogonal to the extending direction, which is arranged in parallel to the in-plane direction of the transparent substrate on one surface of the transparent substrate. A dark color portion having a wedge shape, a trapezoidal shape or a substantially trapezoid shape, and a translucent region between the adjacent dark color portions, and the dark color portion has a dark color in a groove-shaped concave portion having a wedge shape, a trapezoidal shape or a substantially trapezoidal cross section. The transparent region is covered with a transparent protective layer made of a transparent resin, and the minimum particle size dmin and the maximum particle size dmax of the dark color particle and the transparent protection are filled with particles and a transparent resin. An image contrast enhancement filter in which a relationship of “t <dmin <dmax <W” and “t <dmin <dmax <H” is established between the layer thickness t and the maximum width W and depth H of the groove-shaped recess. ,
A layer or film having near infrared absorption ability.

  According to the present invention, the cross-sectional shape is a wedge-shaped, trapezoidal or substantially trapezoidal groove-shaped recess filled with dark particles and a transparent resin, and a transparent protective layer whose surface of the transparent substrate is made of a transparent resin. Covered translucent regions are alternately arranged in parallel in the in-plane direction of the transparent substrate, and the minimum particle size and the maximum particle size of the dark color particles, the thickness of the transparent protective layer, and the groove-shaped recess Since the maximum width and depth of the light are configured as described above, dark particles are not present in the translucent region, and the light transmissivity of the light passing through the translucent region is not deteriorated. As a result, the display image becomes dark and the visibility of the display image is not impaired, and the dark color portion effectively absorbs external light, so that the contrast of the image can be improved.

  A conventional front filter is basically in an exposed state although dark resin remains in the translucent region. Eventually, the translucent area is covered with some kind of member (for example, a front plate), but the exposed translucent area is exposed during various processing steps, transport steps, or storage steps. As a result, there is a problem that the quality of the display image is deteriorated. However, according to the present invention, the translucent region of the transparent substrate is covered with the transparent protective layer made of a transparent resin. Certain translucent areas are not contaminated or scratched. As a result, it is possible to display a high-quality image without degrading the image quality of the display image.

  Furthermore, according to this invention, since it has a layer or film having near-infrared absorptivity, it is provided on the display surface of the image display device, so that there is a risk of causing malfunctions in the remote control of home appliances due to near-infrared radiation radiated from the display. Absent.

  In the optical filter according to the present invention, the layer or film having the near-infrared absorbing ability contains a near-infrared absorber in the transparent base material or the transparent protective layer constituting the image contrast improving filter, Or the layer or film containing a near-infrared absorber is provided in the one surface side or the other surface side of a front image contrast improvement filter.

  According to this invention, the near-infrared absorbing ability can be given to the optical filter by including the near-infrared absorber in any layer or film constituting the optical filter.

  The optical filter according to the present invention further includes an electromagnetic wave shielding film having a conductive mesh, and the electromagnetic wave shielding film is bonded to the image contrast improving filter via an adhesive layer. In this case, the adhesive layer can be configured to contain a near infrared absorber.

  According to the present invention, a high-contrast optical filter having electromagnetic wave shielding ability and near infrared absorption ability can be provided.

  The optical filter according to the present invention further includes a front film having a functional layer, and the front film is bonded to the outermost surface via an adhesive layer. In this case, the adhesive layer can be configured to contain a near infrared absorber.

  According to the present invention, a high-contrast optical filter having a surface protecting ability and a near infrared absorbing ability can be provided.

  In the optical filter according to the present invention, a transparent support is further laminated on the surface of the transparent substrate constituting the image contrast improving filter on the transparent protective layer non-forming side.

  In the optical filter according to the present invention, the layer or film having near-infrared absorption ability is one or more near infrared rays selected from diimonium compounds, phthalocyanine compounds, cyanine compounds, and cesium tungsten composite oxide fine particles. Contains absorbent.

  According to this invention, various near-infrared absorbers having different absorption wavelength ranges, absorptive powers and light transmittances are contained alone or in combination, so that an optical filter having good near-infrared absorptivity and transparency can be obtained. Can be provided.

  An image display device according to the present invention for solving the above-described problems is characterized in that the optical filter according to the present invention is arranged on the display surface of the image display device.

  According to the present invention, since the optical filter according to the present invention described above is provided on the display surface side, it is possible to improve the quality and contrast of the display image, and image display in which near infrared rays are not emitted from the display surface. An apparatus (particularly a plasma display) can be provided.

  According to the optical filter of the present invention, dark particles are not present in the translucent area, and the light transmissivity of the light passing through the translucent area does not decrease. Visibility is not impaired. Moreover, since the dark color portion effectively absorbs external light, the contrast of the image can be improved. Furthermore, since the transparent region of the transparent base material is covered with a transparent protective layer made of a transparent resin, the transparent region that is the transmission region of the image is also present during various processing steps, transport steps, and storage steps. It will not be contaminated or scratched. As a result, it is possible to display a high-quality image without degrading the image quality of the display image. Furthermore, since it has near-infrared absorptivity, by providing it on the display surface of the image display device, there is no possibility of causing malfunctions in the remote control of home appliances.

  According to the image display device according to the present invention, the quality and contrast of the display image can be improved, and an image display device (particularly a plasma display) that does not emit near infrared rays from the display surface can be provided.

They are a typical sectional view (A) showing an example of an image contrast improvement filter which constitutes an optical filter concerning the present invention, and a top view (B) which looked at this from the dark color part side. It is a perspective view of the image contrast improvement filter provided with the transparent support body. It is typical sectional drawing which shows the basic structural example of the optical filter which concerns on this invention. It is typical sectional drawing which shows the specific example of the optical filter which concerns on this invention. It is typical sectional drawing which shows the other specific example of the optical filter which concerns on this invention. It is typical sectional drawing which shows the other specific example of the optical filter which concerns on this invention. It is typical sectional drawing which shows the other specific example of the optical filter which concerns on this invention. It is typical sectional drawing which shows the other specific example of the optical filter which concerns on this invention. It is typical sectional drawing which shows the other specific example of the optical filter which concerns on this invention. It is a process flow figure showing an example of a manufacturing method of an image contrast improvement filter. 1 is a schematic perspective view illustrating an example of an image display device according to the present invention.

  Hereinafter, an optical filter and an image display device according to the present invention will be described with reference to the drawings. The technical scope of the present invention is not limited to the following embodiments.

[Optical filter]
As shown in the basic configuration example of FIG. 3 and the specific examples of FIGS. 4 to 9, the optical filter 100 according to the present invention includes an image contrast enhancement filter 30 and a layer or film having near-infrared absorptivity (hereinafter, For convenience, it is referred to as “near infrared absorption layer 90”.

  The image contrast enhancement filter 30 is one of the characteristic configurations of the optical filter 100 according to the present invention. As shown in FIGS. 1 and 2, the transparent substrate 4 has a transparent substrate 4 on one surface S1. 4 and the light-transmitting region between the adjacent dark-colored portions 10 and 10 and the dark-colored portion 10 having a linear cross-sectional shape parallel to the in-plane direction 4 and perpendicular to the extending direction thereof. 20. The dark-colored portion 10 is configured by filling the groove-shaped concave portion 3 having a wedge-shaped, trapezoidal or substantially trapezoidal cross-section with the dark-colored particles 1 and the transparent resin 2. Moreover, the translucent area | region 20 is transparent protective layer 2L in which the surface S1 of the flat part 8 (the part in which the groove-shaped recessed part 3 is not formed, see FIG.10 (C)) of the transparent base material 4 consists of the transparent resin 2. It is covered with. In the present invention, between the minimum particle diameter dmin and the maximum particle diameter dmax of the dark color particle 1, the thickness t of the transparent protective layer 2L, and the maximum width W and depth H of the groove-shaped recess 3, t < The relationship is dmin <dmax <W and t <dmin <dmax <H.

  The near-infrared absorbing layer 90 is also one of the characteristic structures of the optical filter 100 according to the present invention. As shown in FIG. 4, the front film 40, the image contrast improving filter 30, and the electromagnetic wave shielding film 50 are bonded to each other. It is provided by including a near infrared absorber in any adhesive layer of the adhesive layers 60 and 70 and the adhesive layer 80 that bonds the optical filter 100 to the plasma display 200. Alternatively, as shown in FIGS. 5 to 9, the near-infrared absorbing layer 90 is provided on one surface of the front film 40, the image contrast improving filter 30, or the electromagnetic wave shielding film 50.

  As shown in FIG. 3, the optical filter 100 according to the present invention has one or more functional layers or functional films (hereinafter referred to as “function”) on one surface and / or the other surface of the image contrast enhancement filter 30. "Film") may be provided. FIG. 3A shows an example in which a front film 40 is provided on the surface on which the dark color portion 10 and the translucent region 20 are formed. FIG. 3B shows the dark color portion 10 and the translucent region 20. This is an example in which the electromagnetic wave shielding film 50 is provided on the opposite surface S2 on the side where is formed, and FIG. 3C is an example in which both are provided. In particular, when the optical filter 100 according to the present invention is used as an optical filter for the plasma display 200, a front film 40 and an electromagnetic wave shielding film 50 are further provided as shown in the specific examples of FIGS. Is preferred.

  Hereinafter, each component of the optical filter according to the present invention will be described in detail.

<Image contrast enhancement filter>
As shown in FIG. 1, the image contrast enhancement filter 30 has a dark color portion 10 and a translucent region 20 on one surface S <b> 1 of the transparent substrate 4. More preferably, as shown in FIG. 2, the transparent support 6 is laminated on the surface S <b> 2 on the transparent protective layer non-forming side of the transparent substrate 4.

(Transparent substrate)
As the transparent base material 4, various kinds of resin materials such as ionizing radiation curable resins, thermosetting resins and thermoplastic resins, or inorganic transparent materials such as glass can be used. Usually, a resin material is preferably used in that it is easy to form the groove-like recess 3, can be light and thin, and is excellent in flexibility. About ionizing radiation curable resin and thermosetting resin, it can select from the thing similar to what was illustrated by the description location of the transparent resin mentioned later, and can be used. Examples of the thermoplastic resin include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, polypropylene, cyclic polyolefin, and polymethylpentene, polyvinyl chloride, and polyvinylidene chloride. Styrenic resins such as halogen resins, polystyrene, acrylonitrile-styrene copolymers, cellulose resins such as triacetyl cellulose, diacetyl cellulose, and acetate butyrate cellulose, thermoplastic polyurethane resins, polycarbonate resins, polyamide resins, and the like can be used.

  Since the groove-like recess 3 is formed in the transparent base material 4, the thickness thereof needs to be thicker than the depth H of the groove-like recess 3, and is usually in the range of about 20 μm to 5000 μm. That is, the transparent substrate 4 can take various forms of a so-called film, sheet, or plate depending on its thickness.

(Dark part)
As shown in FIGS. 1 and 2, the dark color portion 10 is formed on one surface S <b> 1 of the transparent substrate 4, and is a straight line arranged in parallel to the in-plane direction of the transparent substrate 4, and The cross-sectional shape orthogonal to the extending direction has a wedge shape, a trapezoidal shape, or a substantially trapezoidal shape. The dark color portion 10 is configured by filling the groove-shaped concave portion 3 having a wedge-shaped, trapezoidal or substantially trapezoidal cross-section with the dark-colored particles 1 and the transparent resin 2.

  First, the shape of the groove-shaped recess 3 will be described. As shown in FIGS. 1 and 2, the groove-shaped recess 3 has a wedge shape, a trapezoidal shape, or a substantially trapezoidal cross-sectional shape. Here, the cross-sectional shape refers to a cross-sectional shape orthogonal to the extending direction of the groove-shaped recess 3 extending linearly. Further, as shown in FIG. 10A, the trapezoidal groove-like recess has a wide width W on one side S1 side (lower base) of the transparent substrate 4 and a side on the other side S2 ( The width of the upper bottom) is configured in a narrow manner. The substantially trapezoidal groove-shaped recess includes a shape having a small width difference between both sides (upper and lower bases), that is, a shape close to a rectangle or a square. Moreover, as a wedge-shaped groove-shaped recessed part, as typically shown in FIGS. 4-9, the shape close | similar to the triangle which the top part (tip | tip) was pointed or a triangle was included. The groove-shaped recess 3 is not limited to such a wedge shape, trapezoid or substantially trapezoid, but may be a square such as a square or a rectangle, or a polygon such as a triangle or a pentagon. Or it is a substantially trapezoid.

  In particular, in terms of compatibility with the effect of improving the image contrast in the presence of external light, the brightness (brightness) of the image, and the high viewing angle of the image, the groove-shaped recess 3 has a wedge-shaped or trapezoidal cross-sectional shape, and What has a significant difference in the width | variety of the opposing both sides (upper bottom and lower bottom) is preferable. The wide side (lower base) and the narrow side (upper base or top) may be on the display surface side of the image display device and on the viewer side, but in either case, the groove depth H is The width (maximum width) W of the wide side (lower base) is preferably larger.

  Thus, unlike the black fiber of the prior art, the groove-like recess 3 can set the maximum width W and the depth H independently, so that the maximum width W is reduced, and if necessary, further grooves The side portion (the depth H direction) of the dark color portion 10 that absorbs most of the external light incident from the oblique direction by increasing the repetition period between the concave portions, increasing the aperture ratio, and increasing the depth H. It is possible to increase the surface area of the side surface. As a result, it is possible to achieve both a high light transmittance of image light and a high light absorption rate of external light, which were impossible with a black fiber mesh. Here, the aperture ratio is the ratio of the area of the opening (the portion where the dark color portion 10 is not formed, that is, the translucent region 20) to the total area viewed from the normal direction of the image contrast enhancement filter 30. Say.

  An angle θ between the inclined surface 5 formed by the interface between the groove-shaped recess 3 and the transparent substrate 4 and the normal line of the light exit surface (line P parallel to the normal incident light with respect to the image contrast enhancement filter 30) is formed at a predetermined angle. For example, θ is preferably in the range of 3 ° to 15 °. This angle range is a range in which a wide side (lower base) and a narrow side (upper base or top) are preferable on the display surface side or the viewer side of the image display apparatus. When θ is 3 ° or more, the display light from the image display device sufficiently reaches the observer side, and an effect of improving luminance can be obtained. In addition, external light that is incident on the screen in an oblique direction can be absorbed by the dark portion 10 having a sufficient slope area (the area of the slope 5), so that reflection of external light is suppressed and image contrast is improved. Can do. Further, if θ is 15 ° or less, the area of the light-transmitting region (dark color portion non-forming region) through which the image light passes can be kept high while maintaining the slope area of the dark color portion 10 that absorbs external light. The intensity (luminance) of image light can be kept high.

  The length of the larger base of the groove-shaped recess 3 (that is, the maximum width W) is preferably about 10 μm to 100 μm, and the length of the smaller base is preferably about 5 μm to 50 μm. The length H is preferably about 10 μm to 200 μm, the period (pitch) of the groove-shaped recess 3 is preferably about 10 μm to 900 μm, and the aperture ratio is preferably about 50% to 90%.

  Next, a material constituting the dark color portion 10, that is, a material filled in the groove-like recess 3 will be described. The dark color portion 10 preferably absorbs most of the visible light wavelength region and absorbs incident visible light (external light) at a high rate. As a result, the external light reflected by the dark color portion 10 is inconspicuous. Even if the reflected light is mixed into the image light, the decrease in the image contrast becomes inconspicuous. Therefore, it is desirable to set the dark color portion 10 to a color that exhibits such an effect. The black color of the dark color portion 10 is ideally ideal, but it is not necessary to be completely black for practical use, and may be a chromatic color as long as it exhibits the above action. Specifically, it may be an achromatic color such as black or dark gray, or a low-lightness chromatic color such as brown, rosy, dark blue, dark green, or dark purple.

  As the dark color particles 1 constituting the dark color portion 10, particles of each color having a predetermined particle diameter can be used. For example, as black particles, black pigments such as carbon black (black) and black iron oxide, resin particles obtained by staining transparent particles such as acrylic with black pigments such as carbon black, and the like are used.

  The dark particles 1 may be pigment particles that are achromatic by mixing various pigments of blue, purple, yellow, and red other than black particles, or resin particles that are dyed with these pigments. Also good. Copper phthalocyanine blue, indanthrene blue, cobalt blue, ultramarine blue, etc. are used as blue pigments, dioxazine violet, etc. are used as purple pigments, and disazo yellow, isoindolinone yellow, yellow lead are used as yellow pigments. As the red pigment, chromophthal red typel, quinacridone red, petal or the like is used, and as the green pigment, copper phthalocyanine green, patina or the like is used. Further, it may be a dark particle 1 having a chromatic color with low brightness, and as an example, one or more of the above-mentioned blue, purple, yellow, red, or green pigments are appropriately mixed and dispersed. If necessary, it may be a colored pigment further mixed with a black pigment, or resin particles obtained by coloring transparent particles such as acrylic with these pigments. Among these dark particles 1, black particles are preferable because they have the highest light absorption and do not affect the hue of the image contrast enhancement filter 30 itself.

  As the particle diameter of the dark particles 1, it is necessary that the minimum particle diameter dmin and the maximum particle diameter dmax satisfy the relationship described later. That is, at least the maximum particle diameter dmax of the dark color particles 1 needs to be smaller than the maximum width W of the groove-shaped recess 3 and smaller than the depth H thereof. On the other hand, the minimum particle diameter dmin of the dark color particles 1 needs to be larger than the thickness of the transparent protective layer 2L. Accordingly, the particle size of the dark particles 1 is arbitrarily selected and used as long as it satisfies such conditions, but is usually arbitrarily selected from the range of 0.1 μm to 100 μm. The minimum particle size dmin and the maximum particle size dmax of the dark color particles 1 can be measured by observing the dark color particles 1 to be used with an electron microscope.

  Various materials such as ionizing radiation curable resin, thermosetting resin, and thermoplastic resin can be used as the transparent resin 2 constituting the dark color portion 10 together with the dark color particles 1. The ionizing radiation curable resin means a resin that is cured by crosslinking or polymerization reaction by irradiation with electromagnetic waves or charged particle beams such as ultraviolet rays or electron beams. Examples of such an ionizing radiation curable resin include an ionizing radiation polymerizable prepolymer and / or an ionizing radiation polymerizable monomer.

  Examples of ionizing radiation polymerizable prepolymers (including oligomers) include polyester (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, polyol (meth) acrylates, silicon (meth) acrylates, Cationically polymerizable functional groups in molecules such as unsaturated polyester-based polymerizable oligomers having radically polymerizable functional groups in the molecule, or novolak-type epoxy resin prepolymers, aromatic vinyl ether-based resin prepolymers, etc. Examples thereof include a polymerizable oligomer having a group. These ionizing radiation polymerizable prepolymers may be used singly or in combination of two or more. Here, “(meth) acrylate” means “acrylate or methacrylate”.

  The ionizing radiation polymerizable monomer (monomer) is preferably a polyfunctional (meth) acrylate which is a polymerizable monomer having a radical polymerizable functional group in the molecule, specifically ethylene glycol di (meth). Acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, etc. It is done. Examples of the monomer having a cationically polymerizable functional group include alicyclic epoxides such as 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate, and glycidyl ethers such as bisphenol A diglycidyl ether, Examples include vinyl ethers such as 4-hydroxybutyl vinyl ether, oxetanes such as 3-ethyl-3-hydroxymethyl oxetane, and the like. These ionizing radiation polymerizable monomers may be used alone or in combination of two or more, or may be used in combination with the ionizing radiation polymerizable prepolymer.

  When an ultraviolet curable resin is used as the ionizing radiation curable resin, it is desirable to add about 0.1 to 5 parts by mass of the photopolymerization initiator with respect to 100 parts by mass of the ionizing radiation curable resin. The initiator for photopolymerization can be appropriately selected from those conventionally used and is not particularly limited.

  As an initiator for photopolymerization, benzoin, benzoin methyl ether, acetophenone, dimethylaminoacetophenone, 2-hydroxy-2-methyl- for a polymerizable monomer or polymerizable oligomer having a radical polymerizable functional group in the molecule 1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, benzophenone, p-phenylbenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal Etc. In addition, for polymerizable monomers and polymerizable oligomers having a cationic polymerizable functional group in the molecule, aromatic sulfonium salts, aromatic diazonium salts, aromatic iodonium salts, metallocene compounds, benzoin sulfonate esters, etc. It is done. Moreover, as a photosensitizer, p-dimethylbenzoic acid ester, tertiary amines, a thiol type sensitizer, etc. can be used, for example.

  Thermosetting resins include phenolic resins, phenol-formalin resins, urea resins, urea-formalin resins, melamine resins, polyester-melamine resins, melamine-formalin resins, alkyd resins, epoxy resins, epoxy-melamine resins, unsaturated polyesters. Examples thereof include resins, polyimide resins, acrylic resins, polysiloxane resins, polyurethane resins, general-purpose two-component curable acrylic resins (acrylic polyol cured products), and the like.

(Translucent area)
The translucent region 20 is as shown in FIGS. The surface S1 of the transparent base material 4 is located between the adjacent dark portions 10 and 10 and covered with the transparent protective layer 2L. In this transparent protective layer 2L, only the transparent resin 2 that fills the groove-shaped recess 3 together with the dark color particles 1 is a groove-shaped recess non-formation portion (also referred to as a convex portion or a translucent opening) of the transparent base material 4. That is, the light-transmitting region 20 is covered. The thickness t of the transparent protective layer 2L is defined by the relationship between the minimum particle size and the maximum particle size of the dark color particles 1 to be used, and is in a range of 0.1 μm to 30 μm as long as the relationship described later is satisfied. It is preferable. When the thickness t of the transparent protective layer 2L is less than 0.1 μm, the transparent protective layer 2L formed on the convex portion which is the flat portion 8 other than the groove-shaped concave portion 3 of the transparent base material 4 is polished or wiped in a normal manufacturing method. It is difficult to realize without the use, and it is insufficient as a protective layer mainly from contamination and scratches on the surface of the translucent region 20. On the other hand, when the thickness t of the transparent protective layer 2L exceeds 30 μm, it is not preferable because the surface protection function becomes excessive quality and unnecessary price increases. In protecting the transparent protective layer 2L from contamination and scratches, an ionizing radiation curable resin or a thermosetting resin having high hardness and excellent scratch resistance is preferable.

(Relationship between dark color and translucent area)
The image contrast enhancement filter 30 is characterized in that the components of the dark color portion 10 and the translucent region 20 are configured as follows. That is, t <dmin <dmax <between the minimum particle diameter dmin and the maximum particle diameter dmax of the dark color particle 1, the thickness t of the transparent protective layer 2L, and the maximum width W and depth H of the groove-shaped recess 3. It is characterized in that it is configured so that the relationship of W and t <dmin <dmax <H is satisfied.

  When the image contrast enhancement filter 30 satisfies such a relationship, the dark color particles 1 exist only in the groove-shaped recess 3 and do not exist in the translucent region 20. On the other hand, the transparent resin 2 exists over both the dark color portion 10 and the translucent region 20, and the translucent region 20 is covered with a transparent protective layer 2 </ b> L made of only the transparent resin 2. Here, the fact that the dark particles 1 are present only in the groove-shaped recesses 3 includes, strictly speaking, those in which a part of the dark color particles 1 are hung in the groove-shaped recesses 3 as shown in FIG. . In particular, in the relationship between the minimum particle size dmin and the thickness t, it is more preferable that dmin / t = 1.5 to 10, and in the relationship between the maximum particle size dmax and W to H, W / dmax = More preferably, it is 2-50, and it is more preferable that H / dmax = 2-100. Note that it is more preferable that H> W from the viewpoint of further improving contrast by absorbing external light.

(Transparent support)
As shown in FIG. 2, the transparent support 6 can be provided on the surface S <b> 2 on the transparent protective layer non-forming side of the transparent substrate 3 as necessary. In the present application, the image contrast enhancement filter provided with the transparent support 6 shown in FIG. 2 is denoted by reference numeral 30B, and the filter not provided with the transparent support 6 shown in FIG. 1 is denoted by reference numeral 30A. The transparent support 6 supports the transparent substrate 4 and reinforces the mechanical strength of the transparent substrate 4, or forms a layer of the transparent substrate 4 and forms the groove-shaped recess 3 on the transparent substrate 4. It is preferably provided for the purpose of providing processing suitability in processing steps such as filling the groove-shaped recess 3 with the composition for forming the dark color portion, forming the transparent protective layer 2L, and laminating the image contrast improving filter 30 on other members. It is what The material of the transparent support 6 can be appropriately selected and applied from the materials described for the transparent substrate 4 described above in light of the purpose of providing the transparent support 6. Further, the thickness of the transparent support 6 may be appropriately selected in view of the purpose of providing the transparent support 6.

  In the example of the perspective view of FIG. 2, a large number of dark color portions 10 are arranged in parallel in the in-plane direction of the transparent substrate 4, are formed in a straight line shape, and the extension direction (y in FIG. 2). The cross-sectional shape orthogonal to (direction) has a trapezoidal shape or a substantially trapezoidal shape.

  When the image contrast enhancement filter 30 is supplied as a continuous belt-like sheet and laminated with the electromagnetic wave shielding film 50 that is also supplied as a continuous belt-like sheet, the extending direction of the dark color portion 10 is the y-axis (image contrast enhancement filter in FIG. It is preferable to incline by a predetermined angle (bias angle) α with respect to the long side direction of 30 and the long side of the optical filter 100.

  With such a configuration, it is possible to prevent the occurrence of moire fringes between the pixels of the image display device and the dark color portion 10 or the conductive mesh 52 of the electromagnetic wave shielding film, and it is possible to improve the mass productivity of the lamination process of each layer. In other words, it is assumed that the angle formed between the extending direction of the dark color portion 10 that can minimize the moire fringe with the pixel and the pixel (horizontal) arrangement direction is α. In the image contrast enhancement filter 30 supplied as a continuous belt-like sheet, when the extending direction of the dark color portion 10 is inclined by a predetermined angle α with respect to the y-axis in FIG. 2, the continuous belt-like image contrast enhancement filter 30 and the continuous belt-like electromagnetic wave. As shown in FIGS. 4 to 9, the shielding film 50 and the continuous belt-like front film 40 are laminated with the long sides of each layer aligned in parallel to form the optical filter 100, and then cut for each screen. . At that time, the continuous belt-like optical filter 100 only needs to be cut parallel or perpendicular to the long side and the short side, and the direction of the cutting blade can be fixed. By doing so, it is not necessary to change or adjust each time according to the bias angle α. This is because the sides (long side and short side) of the optical filter 100 coincide with the sides of the image display device.

  As shown in FIG. 2, when a continuous belt-like sheet in which the extension direction of the dark color portion 10 is formed in parallel with the long side direction of the image contrast enhancement filter 30 is used, the bias angle between the dark color portion 10 and the pixel is set to α. Needs to be cut diagonally so that the long side of the punched rectangle (for one screen) is at an angle α with the long side of the continuous bowl-shaped sheet. In that case, it becomes inevitable that an unusable area to be discarded is generated between the punched screens. On the other hand, from the beginning, if the extending direction of the dark color portion 10 is set to the angle α with the long side direction of the image contrast improving filter 30, the long side of the punched rectangle (one screen) is the length of the continuous bowl-shaped sheet. Since it is flat or perpendicular to the side, it is possible to prevent such an unusable area from occurring between the screens. The bias angle α is preferably 0 ° <α <45 °, particularly preferably 0 ° <α <5 °.

  In order to make the extension direction of the dark color portion 10 form an angle α with the long side direction of the image contrast enhancement filter 30, the groove-like concave portion 3 that is the basis of the dark color portion 10 is formed by the continuous belt-like transparent base material 4 or further What is necessary is just to shape so that the long side of the continuous belt-shaped transparent support body 6 may cross at an angle α. For example, when the groove-shaped recess 3 is formed on the transparent base material 4 with a cylindrical mold (plate), the convex surface corresponding to the groove-shaped recess 3 is cut by screw cutting on the cylindrical surface using a lathe. . At this time, the convex portion may be cut so that the extending direction of the convex portion forms an angle α with both end faces (bottom surface of the cylinder) of the cylinder.

  According to the image contrast enhancement filter 30 described above, the dark particles 1 are not present in the translucent area 20 and the light transmissivity of light passing through the translucent area does not deteriorate, so the display image becomes dark. Therefore, the visibility of the displayed image is not impaired. Moreover, in the dark color part 10, since the dark color particle | grains 1 absorb external light effectively, the contrast (defined by the ratio of the brightness | luminance of a white part and a black part of an image, a difference, etc.) can be improved. Further, since the translucent region 20 is covered with the transparent protective layer 2L, the translucent region 20 that is the transmission region of the image is contaminated or scratched during various processing steps, transport steps, and storage steps. It is possible to display a high quality image without being attached and without degrading the image quality of the display image.

<Electromagnetic wave shielding film>
The optical filter 100 according to the present invention may further include an electromagnetic wave shielding film 50 having a conductive mesh 52. In particular, when the optical filter 100 according to the present invention is used for a plasma display, an electromagnetic wave shielding film 50 is preferably provided. The electromagnetic wave shielding film 50 has at least a transparent substrate 51 and a conductive mesh 52 provided on the transparent substrate 51.

(Transparent substrate)
The transparent substrate 51 may be selected from various thicknesses of various materials in consideration of required transparency such as desired transparency, mechanical strength, and adhesion to the conductive mesh 52. The transparent substrate 51 is preferably a film based on an acrylic resin (here, used as a concept including a methacrylic resin), a polyester resin, or the like, but is not limited thereto. Specific examples of the material for forming the transparent substrate 51 include cellulose resins such as triacetyl cellulose, diacetyl cellulose, and acetate butyrate cellulose, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and ethylene glycol-terephthalic acid. -Polyester resins such as isophthalic acid copolymer, terephthalic acid-ethylene glycol-1,4 cyclohexanedimethanol copolymer, polyester thermoplastic elastomer, polyolefin resins such as polyethylene, polypropylene, polymethylpentene, cyclic polyolefin, polychlorinated Halogen-containing resins such as vinyl and polyvinylidene chloride, polyethersulfone resins, polyacrylic resins, polyurethane resins, polycarbonate resins, styrene resins such as polystyrene , Polyamide resins, polyimide resins, polysulfone resins, polyether resins, polyether ketone, (meth) acrylonitrile and the like can be used. Among them, the biaxially stretched PET film is preferable in that it has excellent transparency and durability, and has heat resistance that does not cause thermal deformation even when subjected to ultraviolet irradiation treatment or heat treatment in the subsequent steps.

  The thickness of the transparent substrate 51 varies depending on the material, but in the case of a PET substrate that is preferably used, it is usually preferably about 100 μm to 188 μm. An easy-adhesion layer (not shown) may be provided on the surface of the transparent substrate 51, or surface treatment such as corona discharge treatment, plasma treatment, or flame treatment may be performed as necessary. The easy adhesion layer is appropriately selected from resins such as urethane resin, epoxy resin, polyester resin, acrylic resin, and chlorinated polypropylene.

(Conductive mesh)
A conductive mesh 52 is provided on the transparent substrate 51. The aspect of the electroconductive mesh 52 is not specifically limited, The thing of various aspects can be mentioned. For example, the conductive mesh 52 may be formed by (1) forming a metal layer on the entire surface of the transparent substrate 51 and then patterning, or (2) an electroless plating catalyst paste on the transparent substrate 51. May be a conductive mesh 52 formed by performing silk screen printing with a mesh pattern and electrolessly plating a metal layer thereon, or (3) intaglio offset printing on a transfer body with a conductive ink composition in a mesh pattern. The conductive mesh 52 formed by transferring the mesh pattern on the transfer body onto the transparent substrate 51 and electroplating the metal layer on the mesh pattern on the transparent substrate 51 may be used. A conductive mesh 52 formed by intaglio printing a conductive ink composition directly on a transparent substrate 51 in a mesh pattern and electroplating a metal layer on the mesh pattern on the transparent substrate 51 (5) The printing plate having a predetermined pattern of recesses filled with an uncured conductive composition, which the applicant has already proposed in the pamphlet of WO2008-149969, and a transfer target of the conductive composition Is bonded to one surface of the transparent base material through a primer layer that can maintain fluidity until it is cured, and then at least the primer layer is cured in a state in which the pressure bonding is retained, and then the transparent group A conductive mesh 52 formed by a specific intaglio printing method in which the material and the primer layer are peeled off from the plate surface and the conductive composition is transferred to the one surface of the transparent substrate through the primer layer in the predetermined pattern. It may be.

  Although the conductive material constituting the conductive mesh 52 differs depending on the forming means exemplified in the above (1) to (5), it cannot be generally stated, but good materials such as gold, silver, platinum, copper, tin, palladium, nickel, aluminum, etc. An electroconductive metal may be sufficient, those alloys may be sufficient, and the electroconductive material which consists of those particle | grains (electroconductive particle) and binder resin may be sufficient.

  In addition, when applying the electromagnetic wave shielding film described in the pamphlet of WO2008-149969 already proposed by the present applicant, silver is interposed on the transparent substrate 51 through a primer layer made of a thermoplastic resin or an ionizing radiation curable resin. A conductive mesh 52 made of a conductive composition in which conductive metal particles such as those are dispersed in a resin is formed. In this embodiment, the printed and solidified conductive composition (conductive mesh 52) is brought into contact with water or an acid such as hydrochloric acid or sulfuric acid, in particular, in order to reduce the resistivity of the conductive mesh 52 (increase the conductivity). Thus, it is preferable to perform a process of fusing and bonding the metal particles in the conductive mesh 52 together. When the treatment is performed in a heated state of about 30 ° C. to 80 ° C., the resistivity reduction effect is good. By such treatment, for example, the surface resistance of the conductive mesh 52 can be reduced from about 1.5Ω / □ to about 0.5Ω / □.

  When the surface resistance of the conductive mesh 52 can be lowered to a sufficient value by such treatment, a sufficient electromagnetic wave shielding property can be exhibited without any metal plating on the surface. If a lower surface resistance is desired, a highly conductive metal such as copper is plated on the conductive mesh. In addition, when the surface resistance value of a desired value or less can be realized by the printed conductive mesh 52 itself, the surface resistance of the conductive mesh 52 at the time of printing may be increased by performing this process. The amount of expensive conductive metal added in the conductive composition can be reduced.

  The pattern of the conductive mesh 52 is a general pattern such as a mesh (mesh or lattice), a stripe (parallel line group or stripe pattern), a spiral (or spiral), or a line segment group as an electromagnetic wave shielding pattern. . Specifically, for example, the line width can be 5 to 200 μm, the line pitch can be 100 to 1000 μm, and the aperture ratio (occupying the total area of the openings in the total area of the conductive mesh pattern) The ratio) is usually about 50 to 95%. The thickness of the conductive mesh 52 varies depending on the resistance value of the conductive mesh, but is usually 2 μm or more and 50 μm or less, and preferably 5 μm or more and 20 μm or less.

  In order to reduce the reflection of external light on the surface of the conductive mesh 52 when external light (electric light, sunlight, etc.) is incident, to improve the image contrast and to sharpen the image, the external light incident on the conductive mesh 52 It is preferable to form a black layer with low light reflectance on the surface on the side. The blackening layer is preferably black, but may also be a low-lightness color (dark color) such as dark gray, brown, amber, dark green, rosy, or dark purple. The material of the blackening layer includes metals such as silver, platinum, copper, metal oxides such as cuprous oxide, cupric oxide, iron tetroxide, silver oxide, silver chloride, silver sulfide, copper sulfide, etc. Metal sulfides, alloys such as copper-cobalt alloys, carbon and the like are used. These materials may be formed as a continuous film having a certain thickness when the iron tetroxide itself is dark, such as black, but when the metal copper itself is not dark. The surface is roughened to form a (light) random surface or fine particles.

  As a method for forming the blackened layer in the case of the conductive mesh 52 formed by printing and solidifying a conductive composition in which silver particles are dispersed in a binder resin, for example, in a hydrochloric acid solution in which tellurium is dissolved. There is a method of immersing the conductive mesh and forming a blackened layer made of silver chloride on the surface of the conductive mesh (the surface of the silver particles) by a chemical reaction.

  As described above, one or both of the conductive mesh 52 of the electromagnetic wave shielding film 50 having the line ridges and the groove-like recesses 3 of the image contrast enhancement filter 30 are used to prevent a decrease in image visibility due to the occurrence of moire fringes. It is preferable to define the angle of the wire hook part. Specifically, the angle α formed by the groove-shaped recess 3 of the image contrast enhancement filter 30 with respect to the long side of the optical filter 100 (corresponding to the horizontal arrangement direction of the pixels of the image display device), the conductive mesh of the electromagnetic wave shielding film 50. For example, the angle β formed by the 52 ridges is preferably 0 ° <α <5 °, 40 ° <β <55 °, and 0 ° <β−α <50 °.

    In order to prevent moiré fringes, in addition to defining the angle of the wire hook part, the outline of the wire hook part of the conductive mesh 52 of the electromagnetic wave shielding film 50 is not a perfect straight line, but a ZIGZAG or wavy broken line, protruding and retracting It is also effective to make the shape of a wavy curve or the like that repeats alternately.

  As illustrated in FIGS. 3 to 9, the electromagnetic wave shielding film 50 is preferably bonded to the image contrast enhancement filter 30 via an adhesive layer 70. By providing the optical filter 100 having such an electromagnetic wave shielding film 50 on the display surface of a plasma display in which unnecessary electromagnetic waves in the 30 MHz to 1 GHz band leak to the outside, the leaking electromagnetic waves are shielded and other devices (for example, remote control) It can be preferably used because it can prevent the influence on the equipment, information processing apparatus, etc.).

<Front film>
As shown in FIG. 3, the optical filter 100 according to the present invention may further include a front film 40 provided on the outermost surface of the optical filter 100 on the viewer side. As illustrated in FIGS. 4 to 9, the front film 40 is provided on the outermost surface of the optical filter 100 on the viewer side, and any one of the antireflection function, the antiglare function, and the scratch resistance function or One or two or more functional layers 42 having two or more functions are provided. The front film 40 has at least a transparent substrate 41 and a functional layer 42 provided on the transparent substrate 41.

(Transparent substrate)
The transparent base material 41 may be selected from various thicknesses of various materials in consideration of required transparency such as desired transparency, mechanical strength, and adhesion to the functional layer 42. The transparent substrate 41 is preferably a film based on an acrylic resin (here, used as a concept including a methacrylic resin), a polyester resin, or the like, but is not limited thereto, and the transparent base of the electromagnetic wave shielding film 50 is not limited thereto. A resin material similar to the material 51 can be used. Among these, a biaxially stretched PET film is preferable because it is excellent in transparency and durability.

  The thickness of the transparent substrate 41 varies depending on the material, but in the case of a PET substrate that is preferably used, it is usually preferably about 100 μm to 188 μm. An easy-adhesion layer (not shown) may be provided on the surface of the transparent substrate 41, or a surface treatment such as corona discharge treatment, plasma treatment, or flame treatment may be performed as necessary. The easy adhesion layer is appropriately selected from resins such as urethane resin, epoxy resin, polyester resin, acrylic resin, chlorinated polypropylene, ionomer, silane coupling agent, alkyl titanate, and isocyanate compound.

  Such an easy-adhesion layer is provided only on one side or both sides of the transparent substrate 41 depending on the required adhesion to the adjacent substrate. Moreover, when providing an easily bonding layer on both surfaces of the transparent base material 41, if the material of the layer adjacent to the front and back surfaces and the adhesiveness required on the front and back surfaces are the same, the easily bonding layers on both the front and back surfaces are the same. Should be used. On the other hand, when the materials of the layers adjacent to the front and back surfaces are different or the adhesiveness required for the front and back surfaces is different, the materials of the layers adjacent to the front and back surfaces are classified into the types of easy-adhesion primers on the front and back surfaces. Depending on the required adhesion, the optimum one may be selected separately.

(Functional layer)
A functional layer 42 is provided on the transparent substrate 41. The functional layer 42 is a layer having one or more functions selected from an antireflection function, an antiglare function, and a scratch resistance function. The functional layer 42 may be a single layer or a multilayer in which a plurality of layers are stacked.

  The antireflection layer having an antireflection function (Anti Reflection layer: AR layer) is a layer particularly for suppressing the reflectance of external light, and has a single-layer structure composed of a functional low refractive index layer or a low refractive index layer. It has a two-layer structure in which a high refractive index layer is arranged so that the low refractive index layer becomes a surface layer or a multilayer structure in which the low refractive index layer is alternately laminated so that the low refractive index layer becomes a surface layer. Such an antireflection layer can be formed on the transparent substrate 41 by a dry film formation method such as vapor deposition or sputtering or a wet film formation method such as coating. Examples of the material for forming the low refractive index layer include silicon oxide, magnesium fluoride, and fluorine-containing resin. Examples of the material for forming the high refractive index layer include titanium oxide, zinc sulfide, zirconium oxide, and niobium oxide. . Here, the high refractive index layer and the low refractive index layer are expressions in the relative relationship of the refractive index between adjacent layers. For example, if the refractive index is higher than a certain layer, the higher side is the higher refractive index layer. It is. The lower side becomes a low refractive index layer. In addition, when providing an anti-scratch function further to an antireflection layer, it can form using the material with high hardness demonstrated in the scratch-resistant function (hard-coat) layer mentioned later suitably.

  An anti-glare layer (Anti Glare layer: AG layer) having an anti-glare function is a layer for preventing glare and is a layer having fine irregularities that irregularly reflect external light on its surface. Such an antiglare layer is formed by coating a transparent substrate 41 with a composition in which an inorganic filler such as silica is added to a binder resin, or by shaping the coated and formed layer surface with a shaping plate. Can be formed. As the binder resin, a curable acrylic resin, an ionizing radiation curable resin similar to the hard coat layer described later, or the like is preferably used because mechanical strength is desired as the surface layer of the front film 40.

  The hard coat layer having the scratch resistance function exhibits a hardness of “H” or higher in a pencil hardness test specified by JIS K 5600-5-4 (1999). The material is not particularly limited as long as such hardness and transparency similar to the transparent resin base material can be realized. Examples of the material for forming the hard coat layer include polyfunctional (meth) acrylate prepolymers such as polyester (meth) acrylate and urethane (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth). ) An ionizing radiation curable resin in which a trifunctional or higher polyfunctional (meth) acrylate monomer such as acrylate is used alone or two or more thereof are selected and blended can be used. Further, when the ionizing radiation curable resin is used as the ultraviolet curable resin, it is preferable to add a sensitizer as a photopolymerization initiator or a photopolymerization accelerator. Here, (meth) acrylate is a composite notation meaning acrylate or methacrylate. The hard coat layer can be formed on the transparent substrate 41 by a wet film formation method such as coating by diluting the above material with a solvent as necessary.

  As shown in FIGS. 3 to 9, the front film 40 having such a functional layer 42 is bonded so as to be the outermost surface of the optical filter 100 through the adhesive layer 60.

<Adhesive layer>
As shown in FIGS. 3 to 9, the optical filter 100 according to the present invention is provided with an adhesive layer as necessary. For example, the front film 40 is bonded to the surface side (observer side) of the image contrast improving filter 30 via the adhesive layer 60, and the adhesive is applied to the back side (plasma display side) of the image contrast improving filter 30. The electromagnetic wave shielding film 50 is bonded through the layer 70. Further, when the optical filter 100 is integrally bonded to the display surface of the plasma display 200, the optical filter 100 is bonded via the adhesive layer 80.

  Examples of the constituent material of the adhesive layer include acrylic resin, polyester resin, urethane resin, polyolefin resin, rubber resin, and vinyl chloride-vinyl acetate copolymer resin. These adhesive resins are used in the form of a thermoplastic resin, a thermosetting resin, or an ionizing radiation curable resin. Usually, an adhesive layer composition containing such a resin material is applied onto a target film to form an adhesive layer, and bonded to another film, and then according to the type of the adhesive layer composition. Glue by means.

  As the form of adhesion, when the resin composition for adhesive is a thermoplastic resin, the following two forms are used.

  (1) Form of heat-melt-type adhesive; the resin composition is heated to its melting point or melting temperature to be in a fluid state, and the image contrast enhancement filter 30 is interposed between the fluid resin composition layers. The front film 40 is laminated, and then the resin composition is cooled to a melting point or a melting temperature or lower and solidified to form the adhesive layer 60, thereby bonding the image contrast improving filter 30 and the front film 40 together. .

  (2) Form of pressure-sensitive adhesive; when the thermoplastic synthetic resin composition exhibits pressure-sensitive adhesive properties at room temperature, the image contrast enhancement filter 30 and the front film 40 are laminated with the resin composition interposed therebetween, The image contrast improving filter 30 and the front film 40 are bonded together only by applying pressure. Here, room temperature refers to the ambient temperature at which the optical filter of the present invention is stored, transported, or used. Usually, it is around 0 ° C to 35 ° C. Such an adhesive is also called a pressure-sensitive adhesive.

  When the adhesive resin composition is in the form of a thermosetting resin, the image contrast enhancement filter 30 and the front film 40 are laminated with the resin composition interposed therebetween, and then the resin composition is heated. Then, the image contrast improving filter 30 and the front film 40 are bonded together by solidifying by the crosslinking reaction, polymerization reaction or the like to form the adhesive layer 60.

  When the adhesive resin composition is in the form of an ionizing radiation curable resin, the image contrast improving filter 30 and the front film 40 are laminated with the resin composition interposed therebetween, and then the resin composition is added. The image contrast improving filter 30 and the front film 40 are adhered by being irradiated with ionizing radiation and solidified by a crosslinking reaction, a polymerization reaction or the like to form an adhesive layer 60. As such ionizing radiation, ultraviolet irradiation or an electron beam is usually used.

  The adhesive layer 60 may be formed on the image contrast improving filter 30 side, the front film 40 side, or both sides of the both sides.

  As shown in FIG. 3, when the adhesive layer 60 is located on the side of the image contrast enhancement filter 30 that is in contact with the dark portion 10 (the groove-like recess 3 filled with the dark particles 1), FIG. Although the surface of the groove-like recess 3 filled with the dark particles 1 (the upper surface in FIG. 3) is a recess, the adhesive layer 60 is filled in the recess. The adhesion is reinforced by the anchoring effect, which is preferable. In the case where the adhesive layer 60 is filled in the concave portion on the surface of the groove-like recess 3, the adhesive has a sufficiently low viscosity and good fluidity during bonding, such as an ionizing radiation curable resin or an adhesive. It is preferable to use a form that can contact the adherend.

  In order to make the surface of the groove-like recess 3 (the upper surface in FIG. 3) a recess, a thermosetting resin or ionizing radiation curable resin having a large shrinkage during curing of the transparent resin 2 in which the dark colored particles 1 are dispersed. The resin or the transparent resin 2 in which the dark particles 1 are dispersed is diluted with a volatile solvent, and then filled into the groove-shaped recess 3, and the solvent is dried to disperse the dark particles 1. This can be realized by shrinking the volume of the transparent resin 2 or controlling the scraping conditions of the doctor blade when the dark color particles 1 and the transparent resin 2 are filled in the surface of the groove-shaped recess 3.

  Although the thickness of an adhesive bond layer is not specifically limited, Usually, about 1-500 micrometers, Preferably it is the range of 2-40 micrometers. Further, such an adhesive layer may contain a near-infrared absorber described later and other functional materials as long as the adhesive properties are not impaired.

<Near infrared absorbing layer>
As shown in FIGS. 3 to 9, the optical filter 100 according to the present invention includes a layer or film having near-infrared absorption ability (referred to as “near-infrared absorption layer 90” for convenience). The near-infrared absorbing ability may be obtained by adding a near-infrared absorber to the layer or film constituting the optical filter 100 and / or newly adding a layer or film containing the near-infrared absorber. It may be provided and provided. “And / or” means that both the layer or film constituting the optical filter 100 contains a near infrared absorber and the layer or film containing the near infrared absorber is newly provided. It may be provided, or any one of them may be provided.

  As a layer or film constituting the optical filter 100 containing a near-infrared absorber, there is basically no limitation, and any one or more layers selected from all constituent layers may be used. For example, (1) the transparent substrate 4 constituting the image contrast improving filter 30 contains a near infrared absorber, and (2) the transparent support 6 constituting the image contrast improving filter 30 contains a near infrared absorber. (3) a transparent substrate 51 of the electromagnetic wave shielding film 50 containing a near infrared absorber, (4) a transparent substrate 41 of the front film 40 containing a near infrared absorber, 5) An adhesive layer 60 for bonding the image contrast improving filter 30 and the front film 40 containing a near infrared absorber (see FIG. 4), (6) Image contrast improving The adhesive layer 70 for bonding the filter 30 and the electromagnetic wave shielding film 50 contains a near-infrared absorber (see FIG. 4). (7) Close to the adhesive layer 80 for bonding the optical filter 100 to the plasma display 200. Examples include those containing an infrared absorber (see FIG. 4). These aspects (1) to (7) may be used singly or in plural.

  Of these, the adhesive layers 60, 70, and 80 need only contain a near-infrared absorber in the composition for the adhesive layer, so that it is not necessary to form a new layer or film, and cost is also reduced. It is an advantage. Among these, when the adhesive layer 70 contains a near-infrared absorber and serves as both the adhesive layer 70 and the near-infrared absorption layer 90, it is particularly preferable in terms of dye durability and adhesive properties as a filter.

  On the other hand, for example, (a) a near-infrared absorbing layer 90 between the transparent base material 41 and the functional layer 42 constituting the front film 40 is provided by providing a layer or film containing a near-infrared absorber. (See FIG. 5), (a) a near-infrared absorbing layer 90 provided on the back side of the front film 40 (image contrast improving filter 30 side, plasma display 200 side) (not shown), (c) A near infrared absorption layer 90 provided on the surface side (observer side) of the image contrast enhancement filter 30 (see FIGS. 6 and 7), (d) the back side of the image contrast enhancement filter 30 (electromagnetic wave shielding film 50 side, A plasma display 200 side) provided with a near-infrared absorbing layer 90 (see FIG. 8), (e) a back side of the electromagnetic wave shielding film 50 (plasma display 20 Those in which a near-infrared absorption layer 90 on the side) (see FIG. 9), and the like. These aspects (a) to (e) may be used singly or in plural.

  Among these, the above (A) and (D) are advantageous in terms of color and durability of the dye as a filter because the metal color is covered from the observer side as a filter.

  Near-infrared absorbers include diimonium compounds, aminium compounds, phthalocyanine compounds, dithiol organometallic complexes, cyanine compounds, azo compounds, polymethine compounds, quinone compounds, diphenylmethane compounds, triphenylmethane compounds, Examples thereof include organic near infrared absorbers such as oxole compounds. Further, a near-infrared absorber containing tungsten oxide fine particles and / or composite tungsten oxide fine particles having an average dispersed particle size of 800 nm or less as described in JP-A-2006-154516, such as CsWO (cesium tungsten oxide), ITO ( An inorganic near-infrared absorber such as indium tin oxide fine particles may be used. Alternatively, the phthalocyanine-based compound aggregate described in Japanese Patent No. 4038572, the cyanine-based compound aggregate described in Japanese Patent Laid-Open No. 2002-22935, and Japanese Patent Laid-Open No. 2001-228324 and Japanese Patent Laid-Open No. 2002-90521 are described. A dye aggregate such as a polymethine compound aggregate, an oxole compound aggregate described in JP 2009-109774 A, or various diimonium compound aggregates may be used. It is desirable to contain one or more selected from these near infrared absorbers according to the characteristics.

In the case where these near-infrared absorbers are contained in the adhesive layer, the blending amount thereof does not hinder the adhesion function and can exhibit a desired near-infrared absorbing ability, and further, transparency due to the near-infrared absorbers. The amount is preferably such that no reduction occurs. The blending amount varies depending on the type of the near infrared absorber, and since it may be blended and blended with the near infrared absorber, it cannot generally be said, but usually, the content after forming as a layer or film , 0.005 to 5.0 g / m ² .

On the other hand, when a near-infrared absorbing layer is provided as a new layer, the near-infrared absorbing agent is blended into an olefin resin such as acrylic resin, polyethylene or propylene, a resin material such as urethane resin, styrene resin or epoxy resin, and the front film. 40, can be formed by coating on either the image contrast enhancement filter 30 or the electromagnetic wave shielding film 50. The blending amount of the near-infrared absorber contained in the resin material is preferably an amount that can exhibit the desired near-infrared absorbing ability and does not cause a decrease in transparency due to the near-infrared absorber. The blending amount varies depending on the type of the near infrared absorber, and since it may be blended and blended with the near infrared absorber, it cannot be generally stated, but as described above, usually, after forming as a layer or a film As content, it exists in the range of 0.005-5.0 g / m < ² >.

(For plasma display applications)
By the way, in the case where the optical filter 100 according to the present invention is provided on the display surface (observer side surface) of the plasma display, it has a near-infrared absorbing ability that does not cause a malfunction in the remote control of home appliances and is transparent ( It must also be excellent in visible light transmission. When the optical filter 100 is provided on the display surface of the plasma display 200, the transparency of the entire optical filter is such that the total light transmittance in the visible light region with a wavelength of 380 to 780 nm is an average of 35% or more in the wavelength region of the range. Preferably there is. By setting the total light transmittance to an average of 35% or more, an image can be enjoyed with sufficient brightness. On the other hand, with respect to the near-infrared absorptivity, it is preferable that the near-infrared transmittance in the wavelength region of 800 to 1100 nm is an average of 30% or less in the wavelength region of the range. More preferably, the transmittance at a wavelength of 850 to 950 nm is 25% or less, which can prevent malfunction of the remote control of the home appliance.

  In selecting a near-infrared absorber, it is necessary to consider the total light transmittance in the visible light region and the near-infrared transmittance in the near-infrared region. Preferable near infrared absorbers are those having low absorption in the visible light region with a wavelength of 380 to 780 nm and high absorption in the near infrared region with a wavelength of 800 to 1100 nm. From this point of view, diimonium compounds, phthalocyanine compounds, cyanine compounds, dithiol organometallic complexes, and tungsten oxide fine particles and / or cesium tungsten composite oxide fine particles described in JP 2006-154516 A It is preferable to include one or more near infrared absorbers selected from infrared absorbers.

  The diimonium compound and the cyanine compound have a feature that they have sufficient near infrared absorption ability in the near infrared region and can easily set the total light transmittance in the visible light region having a wavelength of 380 to 780 nm. As a result, the optical filter 100 as a whole is advantageous in that the average of the total light transmittance in the visible light region is 35% or more.

  On the other hand, the phthalocyanine-based compound has a sufficient near-infrared absorbing ability in the near-infrared region, but has a feature that the average of the total light transmittance in the visible light region having a wavelength of 380 to 780 nm is lowered. For this reason, when a phthalocyanine compound is used alone, its content needs to be reduced. Preferably, a phthalocyanine compound is used in combination with the above-mentioned diimonium compound or cyanine compound. In such a case, the total light transmittance in the visible light region and the near infrared transmittance in the near infrared region are used. Both of them can be easily adjusted within the above-mentioned transmittance range.

  In particular, the phthalocyanine compound has a good absorption ability in the near infrared wavelength range of 800 to 900 nm, the diimonium compound has a good absorption ability in the near infrared range of 900 to 1100 nm, and cesium tungsten has a near infrared absorption range of 800 to 1100 nm. There is a characteristic that the absorption capacity is good in the whole area. Therefore, in consideration of these characteristics and transmittance in the visible light region, blending a phthalocyanine compound and a diimonium compound, or adding cesium tungsten, to obtain a desired near infrared absorber. preferable.

  In addition, such a near-infrared absorber may deteriorate with the ultraviolet-ray in external lights, such as sunlight. Therefore, it is preferable that the layer or film according to the above aspects (1) to (8) or the above (a) to (e) containing a near infrared absorber contains an ultraviolet absorber. Or it is preferable to make the layer or film of the front side (observer side) or film containing a near-infrared absorber contain an ultraviolet absorptivity. Examples of the ultraviolet absorber include organic compounds such as benzotriazole compounds and benzophenone compounds, and inorganic compounds such as fine-particle zinc oxide and cerium oxide. Examples of the binder resin used for the independent layer include a polyester resin, a polyurethane resin, an acrylic resin, and an epoxy resin. Examples of the ultraviolet absorbing film include “Tetron Film HB Type” (trade name) manufactured by Teijin Limited.

  In addition to the ultraviolet absorber, additives such as a radical scavenger and a light stabilizer may be added. Examples of the light stabilizer include hindered amine light stabilizers (such as TINUVIN 111 and 144 manufactured by Ciba) and benzoate light stabilizers. These additives are contained in the near-infrared absorbing layer, or added to the same layer in combination with the ultraviolet absorber.

  In order to improve the durability of each material of the near infrared absorbing layer, a rust inhibitor such as benzotriazole, an antioxidant, and a metal deactivator (for example, Ciba IRGANOX MD1024) may be added.

  Near-infrared absorbers are particularly susceptible to dye deterioration in adhesives. In particular, organic dye systems such as diimonium dyes and cyanine dyes vary depending on the material. In order to improve these durability, a layered clay mineral is added in order to stably hold each pigment in the resin (adhesion / adhesion).

  The layered clay mineral may be a natural product or a chemical compound, or a material having lithium ions, sodium ions, calcium ions, etc., or a substituted or derivative thereof, or a mixture thereof. Especially, smectite functions. Highly preferable. Among the smectites, a smectite purified to remove impurities is preferable, and a lipophilic smectite having a high affinity with a polymer binder resin or an organic solvent is more preferable. By removing the impurities, the pigment mixture is less likely to aggregate when it is produced. Further, a clay mineral or the like in which a quaternary ammonium ion or the like is introduced between the layers of the swellable layered silicate and subjected to a lipophilic treatment is preferable. Examples of the smectite clay include natural or chemically synthesized materials such as hectorite, saponite, stevensite, beidellite, montmorillonite, nontronite, bentonite, and the like, substitution products, derivatives, or mixtures thereof. .

  As the smectite, commercially available ones can be used, including Lucentite STN, STN-A, SPN, SEN, SAN, SAN2C, SAN210, STF, SSN, SSN-A, SAN312-A, SAN2C-A, SAN210-A (lipophilic smectite: manufactured by Corp Chemical), Kunipia T, Kunipia D-36 (montmorillonite; manufactured by Kunimine Industries), Sven N-400, Sven N-400FP (montmorillonite: manufactured by Hojun Co.), Benton (East Shin Kasei Co., Ltd.). Among them, STN-A, SSN-A, SAN312-A, SAN2C, and SAN210 purified to remove impurities are preferable because they hardly aggregate when mixed with a dye compound.

  When these clay minerals are added, the dye durability is improved, but the haze of the near-infrared absorbing layer tends to be improved. Therefore, it is preferable to contain the near-infrared absorbing pigment and the clay mineral in a weight ratio of 1: 0.01 to 1: 1, and more preferably, the weight ratio is 1: 0.001 to 1: 0.5. It is. When there is too much addition amount, the haze of the adhesion layer will be 2.5% or more, and it will become white as a whole. If the added amount is small, the effect is not seen. The haze is preferably within 0.9 to 2.5%.

  As described above, the optical filter 100 in which any layer or film constituting the optical filter 100 contains a near-infrared absorber, or a layer or film containing a near-infrared absorber is newly provided is (1 ) The near infrared ray radiated from the display surface of the plasma display 200 can be efficiently shielded (the average of the near infrared transmittance in the near infrared wavelength region of wavelength 850 to 1100 nm is 30% or less), (2) visible light High transmission performance (average of total light transmittance in a visible light region having a wavelength of 380 to 780 nm is 35% or more) and (3) high image contrast in the presence of external light such as natural light. For example, the electromagnetic wave shielding film 50 and the contrast improving filter used in such an optical filter 100 are members that have a lower transmittance of the member alone than that of the transparent substrate and influence the transmittance of the optical filter 100. By having a near-infrared absorbing layer with high transmittance, high transmittance can be maintained even in combination with these members that lower the transmittance.

<Other functions>
The optical filter 100 according to the present invention requires one or more layers or films selected from, for example, neon light absorption ability, toning function, ultraviolet absorption ability, anti-contamination function, antistatic function, etc. It may be configured to be included depending on Such a layer or film may be provided as a single layer, or a plurality of layers or films may be provided. Further, such a layer or film may be carried on each of the transparent substrates 4, 41, 51 and the transparent support 6 described above, or may be carried on the adhesive layers 60, 70, 80 described above. For these layers or films, those described in paragraphs 0064 and after of JP-A-2007-272161 can be applied.

  Moreover, as a layer which expresses another function, the interruption | blocking layer of a photoinitiator initiator is mentioned as one of the important layers.

  That is, in the optical filter 100 according to the present invention, for example, as shown in FIG. 6A, the layer (or film) containing the near-infrared absorber (the near-infrared absorbing layer 90 in FIG. 6A) is a dark portion. 10 and the transparent protective layer 2 </ b> L (see FIG. 1) that constitutes the light-transmitting region 20. The near-infrared absorber is made of an organic near-infrared absorber such as a diimonium compound, and the transparent resin 2 constituting the transparent protective layer 2L is a photopolymerization initiator such as 1-hydroxy-cyclohexyl-phenyl-ketone. In the case of comprising an ultraviolet curable resin, the photopolymerization start in the transparent protective layer 2L and the organic near-infrared absorber in the layer adjacent to the transparent protective layer 2L chemically react to produce a near-infrared absorbing function. Decreasing phenomenon is likely to occur.

  In order to prevent such deterioration of the near-infrared absorbing function, as shown in FIG. 6B, a transparent protective layer 2L and a near-infrared absorbing layer 90 (a layer or film containing a near-infrared absorber) adjacent to the transparent protective layer 2L, In the meantime, it is preferable to form a blocking layer 35 of the photopolymerization initiator.

  The blocking layer 35 blocks transmission of both a photopolymerization initiator typified by 1-hydroxy-cyclohexyl-phenyl-ketone and an organic near-infrared absorber typified by a diimonium compound and also blocks contact. And a layer having sufficient transparency is not particularly limited. Examples of the material of the blocking layer 35 include acrylic resins such as poly (meth) methyl acrylate, thermoplastic polyester resin resins, thermoplastic urethane resins, thermoplastic resins such as vinyl chloride-vinyl acetate copolymers, polyols and isocyanates. Examples thereof include thermosetting resins such as two-component curable urethane resins, epoxy resins, and melamine resins obtained by reaction with compounds. The thickness of the blocking layer 35 is about 1 to 10 μm.

  In addition, although the various functional layers which comprise the optical filter 100 illustrated above illustrated the form laminated | stacked centering on the transparent base material 41, in order to reduce the number of structural layers, total thickness, and material cost, a transparent substrate The material 41 may be omitted, and a multilayer coating may be formed by applying multilayer coating on the electromagnetic wave shielding film 50, the image contrast enhancement filter 30, or both layers. In the case of multi-layer coating, a predetermined planar view such as a rectangular shape is formed on the conductive mesh 52 of the electromagnetic wave shielding film 50 so as not to form each functional layer on the ground contact area of the peripheral portion for performing ground processing in a subsequent process. It is preferable to apply intermittently in the shape. Intermittent coating is based on coating methods such as die coating and slide coating. In addition, when various functional layers are laminated in a predetermined plan view shape, the layers are applied so that the positions of the layers in the plane are not misaligned (the positions in the plane match).

  When coating each functional layer, it is necessary to make the surface of the coating film smooth and flat so as not to distort the image. For this purpose, it is preferable to adjust the surface tension of the coating film by adding a surfactant, a diluting solvent, or the like in the coating film forming each functional layer. In particular, in the case of a coating film coated on a surface having irregularities such as the electromagnetic wave shielding film 50 and the image contrast improving filter 30, especially a surface made of a cured product of an ionizing radiation curable resin, polyether-modified polydimethylsiloxane, etc. It is preferable to add a dimethylsiloxane-based surface tension adjusting agent (surfactant). Such a coating surface preferably has a contact angle with water of 79 ° or more. Such a coating film surface is laminated with a release film having a smooth surface on the coating film surface when the coating film is uncured, and the coating film is cured with a smooth surface (mirror surface) on the coating film surface, Thereafter, it can be realized by a method of peeling the release film.

[Method for producing image contrast enhancement filter]
Next, an example of manufacturing the image contrast improving filter 30 constituting the optical filter 100 according to the present invention will be described. FIG. 10 is a process flow diagram illustrating an example of a method for manufacturing the image contrast enhancement filter 30.

  First, as shown in FIG. 10 (A), a linear groove arranged parallel to the in-plane direction of one surface S1 and having a cross-sectional shape perpendicular to the extending direction is wedge-shaped, trapezoidal or substantially trapezoidal. A transparent substrate 4 in which the recess 3 is formed is prepared. The groove-shaped recess 3 can be processed by various methods. For example, a hot pressing method in which a heated shaping mold is pressed against a thermoplastic resin, a casting method in which a thermoplastic resin composition is injected onto the shaping mold and solidified, an injection molding method, an ultraviolet curable resin composition It can be formed by arbitrarily selecting a method such as a UV casting method in which it is injected into a mold and UV-cured. Among these methods, the UV casting method excellent in mass productivity is more preferable. The UV casting method can be produced by using a roll-shaped mold and continuously embossing the groove-shaped recess 3 while supplying a continuous sheet. An example of a roll-shaped mold is one in which a copper layer is laminated on the surface of a hollow iron cylinder and the inverted shape of the groove-shaped recess 3 to be formed in the copper layer is formed.

  Next, as shown in FIG. 10B, a liquid resin composition 7 having dark particles 1 and a transparent resin 2 is applied to the surface S1 on the side where the groove-shaped recess 3 is formed. Application can be performed using the nozzle 71 or the like. The liquid resin composition is prepared by arbitrarily selecting the dark color particles 1 and the transparent resin 2 described above, and blending a solvent as necessary to obtain a predetermined viscosity. In addition, in order to improve the ease of manufacture, you may add additives, such as a defoaming agent and a leveling agent, to a liquid resin composition.

  Next, as shown in FIG. 10 (C), the applied liquid resin composition 7 is scraped, and the groove-like recesses 3 are filled with the dark particles 1 and the transparent resin 2, and other than the groove-like recesses. Only the transparent resin 2 is left with a predetermined thickness t ′ without the dark particles 1 being present on the flat portion 8. The scraping can be performed, for example, by a wiping method using a doctor blade, a wiping roll or the like (hereinafter referred to as a doctor blade 72 or the like). In this case, a predetermined gap between the doctor blade 72 or the like and the flat portion 8 is used. This is done by forming a gap. The predetermined gap at this time is such that the thickness t ′ of the transparent resin 2 remaining on the flat portion 8 after scraping is equal to or greater than the thickness t of the transparent protective layer 2L formed by the next solidification step. It forms so that the relationship mentioned later may be satisfy | filled.

  Finally, as shown in FIG. 10 (D), the transparent resin 2 is solidified so that the groove-shaped recess 3 is a dark color portion 10 and the flat portion 8 is covered with a transparent protective layer 2L having a predetermined thickness t. The sex region 20 is assumed. Thus, the image contrast enhancement filter 30 can be manufactured.

  The image contrast improving filter 30 (30A) is manufactured through these steps, and manufacturing conditions are set so that the obtained image contrast improving filter 30 has the following relationship. That is, between the minimum particle diameter dmin and the maximum particle diameter dmax of the dark particles 1, the thickness t ′ of the transparent resin 2 remaining in the flat portion 8, and the maximum width W and depth H of the groove-shaped recess 3 The relationship of t ′ <dmin <dmax <W and t ′ <dmin <dmax <H is established. Therefore, the specifications for the maximum width W and depth H of the groove-shaped recess 3 formed in the transparent substrate 4 to be prepared should satisfy the above relationship, and also satisfy the above relationship when preparing the liquid resin composition. When the dark particle 1 is selected and the liquid resin composition is scraped off by the doctor blade etc. 72, the gap between the doctor blade etc. 72 and the flat portion 8 is adjusted so that the thickness t ′ is obtained.

  As described above, according to the method for manufacturing the image contrast enhancement filter 30, the dark particles 1 are not present in the predetermined thickness t ′ remaining on the flat portion 8 after the liquid resin composition 7 is scraped off, and the transparent resin There are only two. After that, the transparent resin 2 is solidified to manufacture a filter in which the groove-like recess 3 is a dark color portion 10 and the flat portion 8 is a translucent region 10 covered with a transparent protective layer 2L having a predetermined thickness t. it can. The image contrast enhancement filter 30 manufactured in this way does not have the dark color particles 1 in the translucent region 20, and thus the light transmissivity of the light passing through the translucent region 10 does not deteriorate and the display image is dark. Thus, the visibility of the displayed image is not impaired. In addition, since the dark color portion 10 effectively absorbs external light, the contrast of the image can be improved. Furthermore, since the transparent region 20 is covered with the transparent protective layer 2L, the transparent region 20 that is the transmission region of the image is contaminated or scratched even after various processing steps, conveyance steps, storage steps, and the like. Does not stick. As a result, it is possible to display a high-quality image without degrading the image quality of the display image.

[Plasma display]
FIG. 11 is a schematic perspective view showing an example of a plasma display according to the present invention. As shown in FIGS. 4 to 9 and 11, the plasma display 200 is formed by arranging the optical filter 100 according to the present invention on the display surface. By providing the optical filter 100 according to the present invention, the image contrast in the presence of external light can be improved, and the near infrared rays emitted from the plasma display main body can be absorbed.

  As shown in FIGS. 4 to 9, the optical filter 100 may be bonded to the display surface of the plasma display 200 via an adhesive layer 80 or may be fixed without using an adhesive layer. Good. The so-called “adhesive layer” is also a form of “adhesive layer” in the present application.

  In addition, the optical filter 100 is an image contrast enhancement filter 30 having a wedge-shaped, trapezoidal, or substantially trapezoidal dark color portion 10 in which the base of the larger width is arranged toward the viewer (see FIG. 6). Alternatively, it may be arranged toward the plasma display 200 (see FIG. 7). In any direction, the dark color portion 10 can effectively absorb external light.

  As shown in FIG. 7, in the form in which the base of the dark color portion 10 having the larger width is directed toward the plasma display 200, the front film 40 itself is attached to the transparent support 6 of the image contrast enhancement filter 30. By using both, the transparent support 6 and the adhesive layer 60 can be omitted. In this case, for example, a front film 40, which is manufactured in advance from the observer side and is formed by laminating the functional layer 42, the transparent base material 41, and the near-infrared absorbing layer 90, is used as the transparent support. The transparent resin 4 and the groove-like concave portion 3 (dark color portion 10) are formed on the surface of the film 40 on the near infrared absorption layer 90 side by the method as described above.

  Moreover, as shown in FIGS. 4-7, when laminating | stacking the image contrast improvement filter 30 and the front film 40 on the electroconductive mesh 52 of the electromagnetic wave shielding film 50, the following can be illustrated as a preferable form on a manufacturing process. . That is, a heat-melt adhesive made of a thermoplastic resin is used as the adhesive layer 70, and the adhesive layer 70 is heated and melted to correspond to one screen of the image display device on the conductive mesh 52 of the electromagnetic wave shielding film 50. The coating is formed intermittently (partially) only in the area to be applied. Next, a laminate of the image contrast enhancement filter 30 and the front film 40 (both layers are laminated in advance via the adhesive layer 60) is laminated on the molten adhesive layer 70, and then the adhesive layer. 70 is cooled and solidified to complete the bonding. Next, on the region where the adhesive layer 70 is not formed between the intermittently formed adhesive layers 70, the laminate of the electromagnetic wave shielding film 50, the image contrast enhancement filter 30, and the front film 40 is cut into a single sheet to make one screen. Minute optical filter 100 is obtained. Note that the adhesive layer 70 is not formed in the vicinity of both ends of the electromagnetic wave shielding film 50, and the image contrast enhancement filter 30 and the front film 40 are in a non-adhesive floating state on the conductive mesh. Therefore, by grounding up the image contrast enhancement filter 30 and the front film 40, the grounding treatment at both ends can be easily performed.

  As described above, according to the plasma display 200 according to the present invention, since the optical filter 100 according to the present invention is provided on the display surface side, the quality and contrast of the display image can be improved, and near-infrared Radiation can be prevented.

  In the above, the use form which installed the optical filter of this invention in the image display surface of a plasma display (PDP) exclusively was demonstrated. However, the optical filter of the present invention can be installed on the image display surface of other various displays, and can achieve the effects of improving the display image quality and contrast and preventing near-infrared radiation. Examples of other displays include a cathode ray tube display (CRT), a liquid crystal display (LCD), and an electroluminescent display (ELD). In addition, the plasma display and the above-mentioned various displays include a television receiver, a display unit for measuring instruments and instruments, a display unit for office equipment and computer equipment, a display unit for telephones, a display unit for game machines, an advertising medium, and a guide. Used for guidance display boards. Or in addition to full-screen filters for displays, various home appliances such as windows for buildings such as houses, schools, hospitals, offices, stores, vehicles, vehicles, airplanes, ships, etc. It can also be used for electromagnetic shielding and infrared shielding materials such as windows.

  Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. These descriptions do not limit the present invention. In addition, unless otherwise specified, a part represents a weight part (synonymous with a mass part) in an Example.

<Production of image contrast enhancement filter>
First, a 100 μm thick polyethylene terephthalate (PET) sheet (manufactured by Toyobo Co., Ltd .; product name A4300) subjected to easy adhesion on both sides is prepared as a transparent support 6, and an ultraviolet curable resin comprising a urethane acrylate prepolymer is prepared thereon. The resin was applied to a thickness of 300 μm to form an uncured transparent base material. A metal shaping roll that can form a groove-shaped recess 3 having an opening width of 20 μm and a depth of 120 μm on the side where the groove-shaped recess 3 is formed with a pitch of 70 μm is pressed against the surface of the uncured transparent substrate. The transparent resin 4 was cured by irradiating ultraviolet rays from the back side while carving a desired groove-like recess shape. Thus, the groove-shaped recess 3 having an opening width of 20 μm and a depth of 120 μm on the side where the groove-shaped recess 3 was formed with a pitch of 70 μm was formed. In addition, since the groove-shaped recessed part 3 is formed in the circumferential direction, the shaping type | mold roll forms the groove-shaped recessed part 3 so that it may extend in the longitudinal direction of a sheet member by rotating on a sheet member. be able to.

  Next, in 100 parts by mass of a transparent acrylic ultraviolet curable prepolymer, 50 parts by mass of black spherical bead-like particles having a minimum particle size of 2 μm and a maximum particle size of 3 μm, 1-hydroxy-cyclohexyl-phenyl-ketone (product (Name: Irgacure 184, manufactured by Ciba Specialty Chemicals) 2 parts by mass were mixed to prepare a liquid ultraviolet curable resin composition 7. This liquid resin composition 7 was applied onto the groove-like recess forming surface side of the transparent substrate 4 having the groove-like recesses formed as described above, and then wiped with a doctor blade 72. At the time of wiping, the transparent resin 2 which is an ultraviolet curable resin was cured by irradiating ultraviolet rays from the back side simultaneously. In the wiping, the gap between the flat portion 8 of the transparent substrate 4 and the doctor blade 72 was set to 1.5 μm, and the wiping was repeated twice. As a result, the groove-shaped recess 3 is filled with the UV resin as the transparent resin 2 and the black spherical beads as the dark particles 1, while only the transparent resin 2 remains on the flat portion 8 with a thickness of 1.5 μm. The transparent resin 2 was cured by simultaneous UV irradiation to form a transparent protective layer 2L having a thickness of 1 μm. In this way, an image contrast enhancement filter 30 was produced. In the above, [refractive index of transparent resin] − [refractive index of spherical beads] = − 0.003.

<Preparation of electromagnetic shielding film>
A biaxially stretched PET sheet (manufactured by Toyobo Co., Ltd .; product name A4300) having a thickness of 100 μm that has been subjected to double-sided easy adhesion treatment is prepared. The resulting conductive mesh was formed by a copper foil photoetching method. Thus, an electromagnetic wave shielding film 50 was produced.

<Preparation of front film>
A biaxially stretched PET sheet (product name: A4300, manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm subjected to double-sided easy adhesion treatment is prepared, and a refractive index of 1 μm thickness made of an acrylic resin in which zirconium oxide fine particles are dispersed. After forming a 1.93 high refractive index layer by a gravure roll coating method, a 0.138 μm thick refractive index 1.39 made of an acrylate resin in which hollow silica fine particles are further dispersed on the high refractive index layer. A low refractive index layer was formed by a gravure roll coating method to form an antireflection layer. Thus, the front film 40 was produced.

<Preparation of pressure-sensitive adhesive (adhesive) layer A1>
Acrylic adhesive (Toyo Ink Co., Ltd., pressure-sensitive adhesive "Olivein" (trade name: BPS6271), solid content 27%) and curing agent BXX5627 (Toyo Ink Manufacturing Co., Ltd.) as a near infrared absorbing compound Phthalocyanine compound “IR12” (trade name, Nippon Shokubai Co., Ltd.) 0.05 wt%, phthalocyanine compound “IR14” (trade name, Nippon Shokubai Co., Ltd.) 0.02 wt% and diimonium compound “IRG” -068 "(trade name, Nippon Shokubai Co., Ltd.) was added in an amount of 0.01 wt%. Further, 0.01 wt% of a neon light absorbing compound “TAP2” (trade name, Yamada Chemical Co., Ltd.) was blended. Further, 4 wt% of CyasorbUV24 (Cytech) as a UV absorber, 2 wt% of TINUVIN 144 as a light stabilizer and a toning pigment (KAYASET (manufactured by Nippon Kayaku Co., Ltd.)), and Kunipia D36 as a clay mineral are 0.00. An acrylic pressure-sensitive adhesive containing 05 wt% was sufficiently stirred to prepare a pressure-sensitive adhesive layer composition.

This pressure-sensitive adhesive layer composition was applied on a release film having a thickness of 38 μm so as to have a thickness of 25 μm, dried at 100 ° C. for 2 minutes, and then laminated with a release film of 38 μm to release the pressure-sensitive adhesive layer A1. A pressure-sensitive adhesive layer-forming film provided between the mold films was produced. The pressure-sensitive adhesive layer A1 is a phthalocyanine compound "IR12" is 0.05 g / ^{m 2,} phthalocyanine compounds "IR14" is 0.02 g / ^{m 2,} diimmonium compounds "IRG-068" is 0.01 g / ^{m 2} Included to be. Further, the neon light absorbing compound “TAP2” is contained so as to be 0.01 g / m ² .

<Preparation of pressure-sensitive adhesive (adhesive) layer A2>
Acrylic adhesive (Toyo Ink Co., Ltd., pressure-sensitive adhesive “Olivein” (trade name: BPS6271), solid content 27%), near infrared absorbing compound, phthalocyanine compound “IR12” (trade name, Japan) 0.05 wt% of the catalyst (Corporation), 0.1 wt% of the phthalocyanine compound “IR14” (trade name, Nippon Shokubai Co., Ltd.) and the phthalocyanine compound “IR915” (trade name, Nippon Shokubai Co., Ltd.) 0.05 wt% was blended. Furthermore, the neon light absorbing compound “TAP2” (trade name, Yamada Chemical Co., Ltd.) is 0.01 wt%, CyasorbUV24 (Cytech) is 4 wt% as a UV absorber, and TINUVIN 144 is a 2 wt% compound as a light stabilizer. A toning dye (KAYASET (manufactured by Nippon Kayaku Co., Ltd.)) was blended, and an acrylic pressure-sensitive adhesive blended with these compounds was sufficiently stirred to prepare a pressure-sensitive adhesive layer composition.

  This pressure-sensitive adhesive layer composition was applied on a release film having a thickness of 38 μm so as to have a thickness of 25 μm, dried at 100 ° C. for 2 minutes, and then laminated with a release film of 38 μm to release the pressure-sensitive adhesive layer A2. A pressure-sensitive adhesive layer-forming film provided between the mold films was produced.

<Preparation of pressure-sensitive adhesive (adhesive) layer A3>
An acrylic adhesive (Soken Kagaku Co., Ltd., pressure sensitive adhesive SK Dyne SK2094 (trade name), solid content 25%, and curing agent E-5XM), as a near-infrared absorbing compound, cesium tungsten oxide Cs _0.33 WO ₃ 6 g of a particle dispersion (Sumitomo Metal Mining Co., Ltd. YMF-02 (20 wt%)) and 0.01 wt% of a neon light absorbing compound “TAP2” (trade name, Yamada Chemical Co., Ltd.) 4% by weight of CyasorbUV24 (Cytech), 2% by weight of TINUVIN 144 as a light stabilizer and a toning dye (KAYASET (manufactured by Nippon Kayaku Co., Ltd.)) The acrylic adhesive containing these compounds was sufficiently stirred. Thus, a composition for the pressure-sensitive adhesive layer was produced.

This pressure-sensitive adhesive layer composition was applied on a release film having a thickness of 38 μm so as to have a thickness of 25 μm, dried at 100 ° C. for 2 minutes, and then laminated with a release film of 38 μm to release the pressure-sensitive adhesive layer A3. A pressure-sensitive adhesive layer-forming film provided between the mold films was produced. The pressure-sensitive adhesive layer A3 is contained so that Cs _0.33 WO ₃ particles are 1.2 g / m ² . Further, the neon light absorbing compound “TAP2” is contained so as to be 0.01 g / m ² .

<Preparation of pressure-sensitive adhesive (adhesive) layer A4>
Thickness 38 μm, which is a mixture of acrylic adhesive (Toyo Ink Co., Ltd., pressure-sensitive adhesive “Olivein” (trade name), solid content 27%) and 1,2,3-benzotriazole 0.1 wt% The film was coated on the release film to a thickness of 25 μm, dried at 100 ° C. for 2 minutes, laminated with a 38 μm release film, and an adhesive layer A3 containing no near-infrared absorber was placed between the release films. The provided adhesive layer forming film was produced.

<Preparation of pressure-sensitive adhesive (adhesive) layer A5>
Acrylic adhesive (Toyo Ink Co., Ltd., pressure-sensitive adhesive “Olivein” (trade name), solid content: 27%), CyasorbUV24 (Cytec) 4 wt%, 1, 2, 3 as an ultraviolet absorber -Benzotriazole 0.1wt% was mixed and applied on a release film with a thickness of 38µm to a thickness of 25µm, dried at 100 ° C for 2 minutes, then laminated with a 38µm release film, and a near infrared absorber. A pressure-sensitive adhesive layer-forming film was prepared in which a pressure-sensitive adhesive layer A3 containing no was provided between release films.

  In any adhesive, the additive is dissolved in a mixed solution of MEK (methyl ethyl ketone) and toluene and mixed with the adhesive.

<Preparation of adhesive layer A6>
Acrylic adhesive (Toyo Ink Co., Ltd., pressure-sensitive adhesive “Olivein” (trade name), solid content 27%), 1,2,3-benzotriazole 0.1 wt%, toning dye (KAYASET ( Nippon Kayaku Co., Ltd. (several types) and neon light-absorbing dye “TAP2” (trade name, Yamada Chemical Co., Ltd.) 0.01 wt%, UV absorber, CyasorbUV24 (Cytech) 4 wt%, light 2 wt% of TINUVIN 144 was added as a stabilizer, mixed and coated onto a release film having a thickness of 38 μm to a thickness of 25 μm, dried at 100 ° C. for 2 minutes, then laminated with a 38 μm release film, A pressure-sensitive adhesive layer-forming film in which a pressure-sensitive adhesive layer A3 not containing an infrared absorber was provided between release films was produced.

<Preparation of adhesive layer B1>
UV curing resin beam set 575 (Arakawa Kagaku Kogyo Co., Ltd.), near infrared absorbing compound, 24 g of cesium tungsten oxide dispersion (Sumitomo Metal Mining Co., Ltd. YMF-02 (20 wt%)), and tetrane as a neon light absorber. An azaporphyrin-based compound “TAP2” (trade name, Yamada Chemical Co., Ltd.) was blended in an amount of 0.01 wt% and sufficiently stirred to prepare an adhesive layer composition.

The adhesive layer B1 was obtained by applying the composition for an adhesive layer on an arbitrary film, pasting other films together, and then irradiating with ultraviolet rays to bond both films. The adhesive layer B1 formed to a thickness of 25 μm with the adhesive layer composition is included so that Cs _0.33 WO ₃ particles are 1.2 g / m ² .

<Preparation of coating layer C1>
BR-52 (Mitsubishi Rayon Co., Ltd.) was dissolved in an acrylic resin in a mixed solution of 1: 1 weight ratio of MEK: toluene to prepare a 30 wt% solution. As near-infrared absorbing compounds, 0.1 wt% of phthalocyanine compound “IR12” (trade name, Nippon Shokubai Co., Ltd.), 0.05 wt% of phthalocyanine compound “IR14” (trade name, Nippon Shokubai Co., Ltd.), and Diimmonium compound “IRG-068” (trade name, Nippon Shokubai Co., Ltd.) was blended in an amount of 0.03 wt%. Further, 0.01 wt% of a neon light absorbing compound “TAP2” (trade name, Yamada Chemical Co., Ltd.) was blended. Further, a coating solution was prepared by blending 4 wt% of CyasorbUV24 (Cytech) as an ultraviolet absorber and 2 wt% of TINUVIN 144 as a light stabilizer and a toning dye (KAYASET; manufactured by Nippon Kayaku Co., Ltd.). It coated so that the dry film thickness might be set to 10 micrometers on the base-material surface of a functional material.

[Example 1]
From the observer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A5, the image contrast improving filter 30, the adhesive layer A2, the electromagnetic wave shielding film 50, and the adhesive layer A1 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 4 was comprised. At this time, as shown in FIG. 4, the image contrast improving filter 30 is arranged so that the wide side of the wedge-shaped groove-like recess 3 is on the viewer side, and the electromagnetic wave shielding film 50 is also conductive as shown in FIG. The mesh 52 was placed on the viewer side. The pressure-sensitive adhesive layer A1 was transferred from the pressure-sensitive adhesive layer forming film onto the electromagnetic wave shielding film 50.

[Example 2]
From the viewer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A4, the image contrast improving filter 30, the adhesive layer A2, the electromagnetic wave shielding film 50, and the adhesive layer A4 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 4 was comprised. At this time, as shown in FIG. 4, the image contrast improving filter 30 is arranged so that the wide side of the wedge-shaped groove-like recess 3 is on the viewer side, and the electromagnetic wave shielding film 50 is also conductive as shown in FIG. The mesh 52 was placed on the viewer side. The pressure-sensitive adhesive layer A2 was transferred from the pressure-sensitive adhesive layer forming film onto the electromagnetic wave shielding film 50.

[Example 3]
From the observer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A4, the image contrast improving filter 30, the adhesive layer A5, the electromagnetic wave shielding film 50, and the adhesive layer A3 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 4 was comprised. At this time, as shown in FIG. 4, the image contrast improving filter 30 is arranged so that the wide side of the wedge-shaped groove-like recess 3 is on the viewer side, and the electromagnetic wave shielding film 50 is also conductive as shown in FIG. The mesh 52 was placed on the viewer side. The pressure-sensitive adhesive layer A3 was transferred from the pressure-sensitive adhesive layer forming film onto the electromagnetic wave shielding film 50.

[Example 4]
From the viewer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer B1, the image contrast improving filter 30, the adhesive layer A6, the electromagnetic wave shielding film 50, and the adhesive layer A4 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 4 was comprised. At this time, as shown in FIG. 4, the image contrast improving filter 30 is arranged so that the wide side of the wedge-shaped groove-like recess 3 is on the viewer side, and the electromagnetic wave shielding film 50 is also conductive as shown in FIG. The mesh 52 was placed on the viewer side. The pressure-sensitive adhesive layer A4 was transferred from the pressure-sensitive adhesive layer forming film onto the electromagnetic wave shielding film 50.

[Example 5]
From the viewer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A4, the image contrast enhancement filter 30, the adhesive layer B1, the electromagnetic wave shielding film 50, and the adhesive layer A6 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 4 was comprised. At this time, as shown in FIG. 4, the image contrast improving filter 30 is arranged so that the wide side of the wedge-shaped groove-like recess 3 is on the viewer side, and the electromagnetic wave shielding film 50 is also conductive as shown in FIG. The mesh 52 was placed on the viewer side. The pressure-sensitive adhesive layer A4 was transferred from the pressure-sensitive adhesive layer forming film onto the electromagnetic wave shielding film 50.

[Example 6]
From the viewer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A4, the image contrast improving filter 30, the adhesive layer A6, the electromagnetic wave shielding film 50, and the adhesive layer A4 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 5 was comprised. In Example 6, as the front film 40, the adhesive layer C1 was formed as the near-infrared absorbing layer 90 on the transparent base material 41, and the high refractive index layer and the low refractive index layer were formed thereon in that order. A front film 40 was used. As in the above embodiment, the image contrast enhancement filter 30 is arranged so that the wide side of the wedge-shaped groove-like recess 3 is on the viewer side as shown in FIG. 5, and the electromagnetic wave shielding film 50 is also shown in FIG. As shown, the conductive mesh 52 was placed on the viewer side, and the pressure-sensitive adhesive layer A4 was transferred onto the electromagnetic wave shielding film 50 from the pressure-sensitive adhesive layer forming film.

[Example 7]
From the observer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A5, the image contrast improving filter 30, the adhesive layer A4, the electromagnetic wave shielding film 50, and the adhesive layer A4 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 7 was comprised. In Example 8, as the image contrast enhancement filter 30, the image contrast enhancement filter 30 in which the adhesive layer C1 was formed as the near infrared absorption layer 90 on the transparent support 6 was used. As shown in FIG. 7, the image contrast enhancement filter 30 is arranged so that the wide side of the wedge-shaped groove-shaped recess 3 is the display surface side of the plasma display 200, and the electromagnetic wave shielding film 50 is as shown in FIG. The conductive mesh 52 was placed on the viewer side, and the pressure-sensitive adhesive layer A4 was transferred onto the electromagnetic wave shielding film 50 from the pressure-sensitive adhesive layer forming film.

[Example 8]
From the observer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A5, the image contrast improving filter 30, the adhesive layer A4, the electromagnetic wave shielding film 50, and the adhesive layer A4 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 8 was comprised. In Example 9, as the image contrast enhancement filter 30, the image contrast enhancement filter 30 in which the adhesive layer C1 was formed as the near infrared absorption layer 90 on the transparent support 6 was used. As in the above embodiment, the image contrast enhancement filter 30 is arranged so that the wide side of the wedge-shaped groove-shaped recess 3 is on the viewer side as shown in FIG. 8, and the electromagnetic wave shielding film 50 is also shown in FIG. As shown, the conductive mesh 52 was placed on the viewer side, and the pressure-sensitive adhesive layer A4 was transferred onto the electromagnetic wave shielding film 50 from the pressure-sensitive adhesive layer forming film.

[Example 9]
From the viewer side toward the display surface side of the plasma display 200, the front film 40, the adhesive layer A4, the image contrast enhancement filter 30, the adhesive layer A5, the electromagnetic wave shielding film 50, and the adhesive layer A4 are laminated in this order. The optical filter 100 of the aspect shown in FIG. 9 was comprised. In Example 10, as the electromagnetic wave shielding film 50, the electromagnetic wave shielding film 50 in which the adhesive layer C1 was formed as the near infrared absorption layer 90 on the transparent substrate 51 was used. As in the above embodiment, the image contrast enhancement filter 30 is arranged so that the wide side of the wedge-shaped groove-like recess 3 is on the viewer side as shown in FIG. 9, and the electromagnetic wave shielding film 50 is also shown in FIG. As shown, the conductive mesh 52 was placed on the viewer side, and the pressure-sensitive adhesive layer A4 was transferred onto the electromagnetic wave shielding film 50 from the pressure-sensitive adhesive layer forming film.

[Comparative Example 1]
In Example 1, instead of the spherical bead-shaped particles, black spherical bead-shaped particles having a minimum particle diameter of 0.2 μm and a maximum particle diameter of 3 μm were used, and an adhesive layer A3 was used instead of the adhesive layer A1. Otherwise, the filter of Comparative Example 1 was obtained in the same manner as in Example 1.

[Measuring method]
(Total light transmittance)
The total light transmittance of the optical filters of Examples 1 to 10 and Comparative Example 1 was measured using a Nippon Denshoku Industries Co., Ltd. haze meter (NDH2000).

(Near infrared transmittance)
Using a spectrophotometer (trade name: “UV-3100PC” manufactured by Shimadzu Corporation), a test piece having a size of 50 mm × 50 mm cut out from each optical filter was measured.

(Image contrast)
The existing optical film was removed from the front substrate of a commercially available PDP display device (product name “W42P-H8000” (42 inches), manufactured by Hitachi, Ltd.), and the optical filters of Examples 1 to 10 and Comparative Example 1 It abuts on the display surface and is stuck by applying pressure with a rubber roller. And six 40W white fluorescent lamps (product name “Neoline White FL40S-W”, manufactured by Toshiba Corporation) in the direction 30 ° diagonally above the PDP with the optical filter attached (horizontal distance 1570 mm, vertical distance 907 mm) , And with the ambient light set so that the illuminance at the center of the surface of the PDP display is 100 lux and 1000 lux as measured by the luminance meter, the contrast sensation is visually observed from the front of the PDP (horizontal distance 1570 mm). Evaluation was performed. In contrast evaluation, the image quality (brightness, contrast, etc.) of the PDP is set to the “standard” mode, and the image data of the highest density of the achromatic color (complete black) and the lowest density of the achromatic color (complete white). The image data of a pattern in which grids (rectangular grids) are alternately arranged in two colors are displayed, and whether or not the black-and-white boundary of the pattern is clearly visible is judged.

  In the optical filters of Examples 1 to 9, the black-and-white boundary was clearly visible, but the optical filter of Comparative Example 1 was not clearly visible.

DESCRIPTION OF SYMBOLS 1 Dark particle 2 Transparent resin 2L Transparent protective layer 3 Groove-shaped recessed part 4 Transparent base material 5 Slope 6 Transparent support 7 Liquid resin composition 8 Flat part 10 Dark color part 20 Translucent area | region 30, 30A, 30B Image contrast improvement filter 40 Front film 41 Transparent substrate 42 Functional layer (AR layer, AG layer, etc.)
50 Electromagnetic wave shielding film (back film)
DESCRIPTION OF SYMBOLS 51 Transparent base material 52 Conductive mesh 60,70,80 Adhesive layer or near-infrared absorber containing adhesive layer 90 Near-infrared absorption layer or film 100 Optical filter 200 Plasma display

dmin Minimum particle size of dark particles dmax Maximum particle size of dark particles t Thickness of transparent protective layer t 'Thickness of transparent resin on flat portion H Depth of groove-shaped recess W Maximum width of groove-shaped recess P Normal θ Angle between slope and normal

Claims (9)

On one surface of the transparent substrate, a linear cross-sectional shape arranged in parallel to the in-plane direction of the transparent substrate and perpendicular to the extending direction is adjacent to a dark color portion having a wedge shape, a trapezoidal shape, or a substantially trapezoidal shape. A translucent region between the dark color portions, and the dark color portion is filled with dark particles and a transparent resin in a groove-shaped recess having a wedge shape, a trapezoidal shape or a substantially trapezoidal cross section. The area is covered with a transparent protective layer made of a transparent resin, and the minimum particle diameter dmin and maximum particle diameter dmax of the dark particles, the thickness t of the transparent protective layer, the maximum width W of the groove-shaped recess, and An image contrast enhancement filter satisfying a relationship of “t <dmin <dmax <W” and “t <dmin <dmax <H” with the depth H;
A layer or film having near infrared absorption ability;
An optical filter comprising:   The near-infrared absorbing layer or film contains a near-infrared absorber in the transparent base material or the transparent protective layer constituting the image contrast improving filter, or a previous image contrast improving filter. The optical filter according to claim 1, wherein a layer or a film containing a near-infrared absorber is provided on one surface side or the other surface side.   The optical filter according to claim 1, further comprising an electromagnetic wave shielding film having a conductive mesh, wherein the electromagnetic wave shielding film is bonded to the image contrast enhancement filter via an adhesive layer.   The optical filter according to claim 3, wherein the adhesive layer contains a near infrared absorber.   The optical filter according to claim 1, further comprising a front film having a functional layer, wherein the front film is bonded to the outermost surface via an adhesive layer.   The optical filter according to claim 5, wherein the adhesive layer contains a near infrared absorber.   The optical filter according to any one of claims 1 to 6, wherein a transparent support is further laminated on a surface of the transparent substrate constituting the image contrast improving filter on the transparent protective layer non-forming side.   The layer or film having near infrared absorption ability contains one or more near infrared absorbers selected from diimonium compounds, phthalocyanine compounds, cyanine compounds, and cesium tungsten composite oxide fine particles. The optical filter according to any one of 1 to 7.   An image display device comprising the optical filter according to any one of claims 1 to 8 arranged on a display surface of an image display device.

Images