JP2000250420A - Front plate for image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a front plate having not only an antireflection function but a function to shield against near IR rays, a function to shield against electromagnetic waves and a proper color compensation function by forming a visible ray filter layer which contains dyes and a polymer binder and which absorbs visible rays. SOLUTION: This front plate of an image display device is equipped with one or two transparent supporting bodies 4, 6, a visible ray filter layer 5 which contains dyes and a polymer binder and which absorbs visible rays, a shielding filter layer 2 having either a function to shield against IR rays or a function to shield against electromagnetic waves or both of the functions, and an antireflection layer 1 having an antireflection function against visible rays. Base coating layers are preferably formed between the plastic transparent supporting body 4 and a hard coating layer 3 and between the plastic transparent supporting body 4 and the filter layer 5 so as to obtain enough adhesion strength. The filter layer 5 and the glass transparent supporting body 6 can be easily adhered by using, for example, a commercially available acrylic adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antireflection layer having a filter layer, a transparent support, a near-infrared shielding layer, an electromagnetic wave shielding layer, and a low refractive index layer. In particular, the present invention relates to a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescent display (ELD), a cathode ray tube display (CRT), a fluorescent display tube,
The present invention relates to a front panel attached to a display of an image display device such as a field emission display for antireflection, near-infrared shielding, electromagnetic wave shielding, and color reproducibility improvement.

[0002]

2. Description of the Related Art In recent years, various types of image display devices (displays) such as a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode ray tube display (CRT), a fluorescent display tube, Field emission displays have been developed and devices incorporating them have been put into practical use. These image display devices have various problems, for example, a problem that the color purity and color separation of the display element are insufficient, a problem that the contrast is reduced due to the background being reflected on the display, and a problem of infrared and electromagnetic waves caused by the display element. There is a problem of external leakage. For each of these problems, it has been proposed to use, for example, a visible filter for color separation, an antireflection film, an infrared shielding filter, an electromagnetic shielding filter, or the like on the front surface of the display. However, each of these filters requires various tasks depending on the type of display. For example, a visible light filter for color separation needs to form a sharp absorber according to the characteristics of the display element. In addition to this, heat resistance such as kneading in glass and enhancement of physical properties are required. In addition, the antireflection film needs to be multilayered in order to obtain an ideal reflectance in all visible light regions,
Forming a multilayer film by a vapor deposition method or a coating method involves problems of process difficulties and high costs. Therefore, if the front panel of the display is to have many functions, in addition to the characteristics required for the filter of each function, there is a restriction that one function must not interfere with the other functions. Therefore, a multifunctional front panel has not yet been put to practical use.

[0003]

In developing a multifunctional front panel, it is necessary to solve various problems depending on the functions to be combined. As an example, a case where a reflection prevention function is combined with a visible filter for color correction will be described as an example. Attempts have been made to impart the function of a visible filter by coloring a member constituting the antireflection film, for example, a transparent support or a hard coat layer. However, in this case, the dye or pigment that can be added to the transparent support or the hard coat layer is
The types are very limited. The reason is that the transparent support is made of plastic or glass (usually plastic)
Manufacture from. Therefore, dyes and pigments to be added to the transparent support are required to have extremely high heat resistance enough to withstand the temperature during the production of the support. On the other hand, the hard coat layer
Generally, it is a layer containing a cross-linked polymer. The crosslinking reaction of the polymer is performed by heating or irradiating light or the like after the application of the layer. The reaction conditions for this crosslinking are due to the fact that there are many dyes and pigments that fade. Furthermore, dyes or pigments used for color correction are required to have various absorption spectrum characteristics depending on the type of image display device. If the types of dyes and pigments used for color correction are limited for the above reasons, it is difficult to perform appropriate correction.

[0004] In order to avoid the above-mentioned restrictions, it is easily considered that a dye is added to a polymer layer which can be formed under mild conditions, instead of a transparent support or a hard coat layer, and a colored layer is provided as an independent visible filter layer. . However, unlike the hard coat layer, the colored polymer layer has a low affinity for the transparent support (plastic or glass) and the low refractive index layer in the antireflection film, and has a disadvantage that a failure such as peeling is likely to occur. As described above, it is necessary that the material of the multifunctional front panel is restricted, and that the arrangement of the filter layers for each function be devised. Accordingly, an object of the present invention is to provide a multifunctional front panel having excellent manufacturability and high mechanical strength, and particularly, in addition to an anti-reflection function, a near-infrared shielding function, an electromagnetic wave shielding function, and appropriate color correction. It is to provide a front plate having a function.

[0005]

The object of the present invention has been attained by the following front plate. (1) One or two transparent supports, a visible filter layer for absorbing visible light containing a dye and a polymer binder, a shielding filter layer having one or both of an infrared shielding function and an electromagnetic wave shielding function, visible light A front plate for an image display device provided with an anti-reflection layer having an anti-reflection ability against the image. (2) The front plate for an image display device according to item 1, wherein the infrared ray shielding function is a near infrared ray shielding function. (3) The electromagnetic wave shielding function has a frequency of 10 MHz or more and 20
3. The front plate for an image display device according to claim 1, wherein the front plate has a function of shielding electromagnetic waves in a range of 0 MHz. (4) The antireflection layer includes one or more layers having a refractive index lower than the refractive index of the support.
A front plate for an image display device according to any one of the above. (5) The visible filter layer has a wavelength of 500 to 550.
The absorption maximum with a transmittance of 50 to 85% is in the range of nm, and the transmittance is 5 to 60 in the range of 560 to 620 nm.
Item 5. The front plate for an image display device according to any one of Items 1 to 4, which is a visible filter having an absorption maximum of 5%. (6) at least one of the transparent supports is glass;
Item 6. The front plate for an image display device according to any one of Items 1 to 5, wherein another one is a transparent plastic plate. (7) The transparent plastic plate according to any one of items 1 to 6, wherein the transparent plastic plate is a transparent support having at least one surface provided with an undercoat layer containing a polymer having a glass transition temperature of 60 ° C or lower and -20 ° C or higher. A front plate for an image display device according to any one of the above. (8) The undercoat layer provided on the transparent plastic plate,
Item 8. The transparent support according to item 7, wherein the first undercoat layer adjacent to the transparent support is made of a styrene-butadiene copolymer, and the second undercoat layer is made of an acrylic resin layer. A front plate for an image display device, characterized in that: (9) The front plate for an image display device according to any one of (1) to (8), wherein the shielding filter layer has a silver transparent thin film layer. (10) The front plate for an image display device according to any one of items 1 to 9, wherein the front plate has antireflection layers on both sides thereof. (11) The front plate for an image display device according to any one of items 1 to 10, wherein the front plate has at least one layer among a hard coat layer, an antifouling layer, and an antiglare layer. (12) The front plate has a configuration in which an antireflection layer, a shielding filter layer, a glass plate, a visible filter layer, a transparent plastic plate, and an antireflection layer are laminated in this order from the observation side. A front plate for an image display device according to any one of claims 11 to 11. (13) The front plate for PDP according to any one of Items 1 to 12, wherein the front plate is used for a plasma display device.

[0006]

The present inventor has proceeded with the research, and has provided an undercoat layer between the transparent support and the filter layer and between the transparent support and the antireflection layer or the hard coat layer to thereby form the transparent support and the filter layer. Further, it was studied to enhance the adhesive strength between the transparent support and the antireflection layer or the hard coat layer. However, the provision of the undercoat layer must not impair the optical function of the antireflection layer. As a result of further studies by the present inventors, the glass transition temperature of the transparent support surface on which the filter layer is applied and the transparent support surface on which the antireflection layer or the hard coat layer is applied is 60 ° C. or lower.
The undercoat layer containing a polymer having a temperature of at least ℃ is controlled by controlling the refractive index and film thickness of each undercoat layer, without affecting the optical function of the antireflection film. Succeeded in enhancing the adhesive strength between the antireflection layer and the hard coat layer. As a result of eliminating the problem of adhesion between the transparent support and the filter layer, various types of dyes can be used for the filter layer. For example, in the field of silver halide photography, various photographic dyes have been developed. The absorption spectral properties of photographic dyes have also been studied in detail. It has been difficult to add a photographic dye to a transparent support or a hard coat layer by a conventional method. According to the present invention, various photographic dyes can be used for the antireflection film. In addition, as a result of eliminating the problem of adhesive strength between the transparent support and the antireflection layer or the hard coat layer, layers having various functions can be laminated, and in addition to the antireflection property, visible light selective absorption It has become possible to produce a front plate for an image display device having various functions such as characteristics, near-infrared shielding characteristics, electromagnetic wave shielding characteristics, and scratch resistance. As a result, in the front plate of the present invention, in addition to the anti-reflection function, a near-infrared shielding function, an electromagnetic wave shielding function, and an appropriate color correction function according to the type of the image display device can be obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical layer structure of a front plate for an image display device according to the present invention will be described with reference to the drawings. The layer structure when used as a front panel for a cathode ray tube display (CRT) and a plasma display panel (PDP) or as a part thereof will be described. FIG. 1 is a conceptual cross-sectional view when a front plate D of the present invention is used on the front surface of a main body A of a cathode ray tube display (CRT) or a plasma display panel (PDP). FIG. 1-1 shows a case where the main body A and the front plate D are in close contact with each other and various filter layers and antireflection layers are provided only on one surface (front surface) of the support of the front plate.
FIG. 1-2 is a conceptual diagram in the case where there is a space between the main body A and the front plate D, and various filter layers and antireflection layers are provided on both surfaces of the support of the front plate. FIG. 2 is a schematic sectional view of the layer configuration of the antireflection film. FIGS. 2-1 and 2-2 are examples of the layer configuration of the front plate corresponding to the arrangement of FIG.
FIGS. 2-3 and 2-4 are examples of the layer configuration of the front plate corresponding to the arrangement of FIG. 1-2. In FIG. 2A, it is preferable to provide an undercoat layer between the plastic transparent support and the hard coat layer and between the plastic transparent support and the filter layer in order to obtain a sufficient adhesive strength. In FIG. 2-2, it is preferable to provide an undercoat layer between the transparent plastic support and the filter layer in order to obtain a sufficient adhesive strength.
The filter layer and the glass transparent support can be easily adhered using, for example, a commercially available acrylic pressure-sensitive adhesive. In FIGS. 2-3 and 2-4, it is preferable to provide an undercoat layer between the plastic transparent support and the filter layer and between the plastic transparent support and the antireflection layer in order to obtain a sufficient adhesive strength.

Hereinafter, each material constituting the front plate of the present invention and its structure will be described. (Transparent plastic plate) Examples of the material forming the transparent support include cellulose esters (eg, diacetyl cellulose, triacetyl cellulose (TAC), propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, nitrocellulose), polyamide, polycarbonate , Polyester (eg, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, poly-1,4-cyclohexane dimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4′-dicarboxylate, polybutylene terephthalate) , Polystyrene (eg, syndiotactic polystyrene), polyolefin (eg, polyethylene, polypropylene, polymethylpentene), acrylic (polymethylmethacrylate) Acrylate, polysulfone, polyethersulfone, polyetherketone, polyetherimide and polyoxyethylene. Preferred are triacetyl cellulose, polycarbonate, polymethyl methacrylate, polyethylene terephthalate and polyethylene naphthalate. The transmittance of the transparent support is 8
It is preferably at least 0%, more preferably at least 86%. The haze is preferably at most 2%, more preferably at most 1%. The refractive index is preferably from 1.45 to 1.70. An infrared absorber or an ultraviolet absorber may be added to the transparent support. The amount of the infrared absorbing agent added is 0.1% of the transparent support.
It is preferably from 0.01 to 20% by weight, more preferably from 0.05 to 10% by weight. Further, as a slipping agent, particles of an inert inorganic compound may be added to the transparent support. Examples of inorganic compounds include SiO ₂ , Ti
_{O 2, BaSO 4, CaCO 3} , talc and kaolin. The transparent support is preferably subjected to a surface treatment in order to further enhance the adhesiveness with the undercoat layer. Examples of surface treatment include chemical treatment, mechanical treatment, corona discharge treatment, flame treatment, ultraviolet irradiation treatment, high frequency treatment, glow discharge treatment, active plasma treatment, laser treatment, mixed acid treatment,
And ozone oxidation treatment included. Glow discharge treatment, ultraviolet irradiation treatment, corona discharge treatment and flame treatment are preferred, and corona discharge treatment is more preferred.

(Undercoat layer) In the present invention, the glass transition temperature between the transparent support and the filter layer is 60 ° C. or lower.
An undercoat layer containing a polymer at 0 ° C. or higher or an undercoat layer having a rough surface on the filter layer side is provided. Further, in the present invention, two undercoat layers including a polymer layer having a glass transition temperature of 60 ° C. or lower and −20 ° C. or higher are provided between the support and the antireflection layer. This improves the adhesive strength between the transparent support and the filter layer and between the transparent support and the antireflection layer. In this case, the thickness and the refractive index of the two-layer undercoat layer between the antireflection layer and the transparent support satisfy both the following formulas (I) and (II) so as not to impair the function as the antireflection layer. It must be provided with a film thickness and a refractive index value. (I) 140 nm ≦ t ₁ + t ₂ ≦ 200 nm (II) 1.50 ≦ n ₁ ≦ 1.60, 1.45 ≦ n ₂ ≦ 1.5
5 Here, t ₁ : film thickness of the first undercoat layer in contact with the transparent support, t ₂ : _second film thickness
Film thickness of undercoat layer n ₁ : refractive index of first undercoat layer in contact with transparent support, n ₂ :
This is the refractive index of the second undercoat layer. The thickness of the undercoat layer between the transparent support and the filter layer is preferably 20 nm to 1 μm, and 50 to 70 μm.
0 nm is more preferred. The undercoat layer may be composed of two or more different layers. An undercoat layer containing a polymer having a glass transition temperature of 60 ° C. or lower and −20 ° C. or higher adheres the transparent support and the filter layer due to the tackiness of the polymer.
Polymers having a glass transition temperature of 60 ° C or lower and -20 ° C or higher are obtained by polymerization or copolymerization of vinyl chloride, vinylidene chloride, vinyl acetate, butadiene, neoprene, styrene, chloroprene, acrylate, methacrylate, acrylonitrile or methyl vinyl ether. Obtainable. Glass transition temperature is not higher than 60 ° C.-2
The temperature is preferably 0 ° C or higher, more preferably 55 ° C or lower and -15 ° C or higher, and most preferably 50 ° C or lower and -10 ° C or higher. The undercoat layer having a rough surface adheres the transparent support and the filter layer by forming a filter layer on the rough surface. The undercoat layer having a rough surface can be easily formed by applying a polymer latex. Glass transition temperature of 60 ° C or less -20
An undercoat layer containing a polymer having a glass transition temperature of not higher than 60 ° C. and not lower than −20 ° C. and having a rough surface on the filter layer side may be formed by using a polymer latex having a temperature of not lower than 60 ° C. The average particle size of the latex used for the undercoat layer between the filter layer and the transparent support and between the antireflection layer and the transparent support is preferably 0.02 to 3 μm,
More preferably, the thickness is from 1 to 1 μm. As the undercoat layer composed of two layers between the antireflection layer and the transparent support, a configuration in which the first layer is composed of a styrene-butadiene copolymer and the second layer is composed of an acrylic resin layer can be preferably used. Such undercoat layers are described in JP-A-10-166.
The embodiment described in JP-A-517-517 can be preferably used. The undercoat layer may contain a solvent for swelling the transparent support, a matting agent, a surfactant, an antistatic agent, a coating aid, and a hardener.

(Second Undercoat Layer of Filter Layer) A second undercoat layer may be provided between the undercoat layer and the filter layer. As the second undercoat layer, a polymer having a high affinity for the binder polymer of the filter layer (for example, acrylic resin,
It is preferably formed using a cellulose derivative, gelatin, casein, starch, polyvinyl alcohol, soluble nylon, or polymer latex. A solvent for swelling the transparent support, a matting agent, a surfactant, an antistatic agent, a coating aid, a hardening agent, and the like can be added to the second undercoat layer.

(Anti-reflection layer) As the anti-reflection layer, it is essential to provide a low refractive index layer on the outermost surface. The refractive index of the low refractive index layer is lower than the refractive index of the transparent support. The low refractive index layer preferably has a refractive index of 1.20 to 1.55, more preferably 1.30 to 1.55. The thickness of the low refractive index layer is preferably from 50 to 400 nm, more preferably from 50 to 200 nm. The low refractive index layer is a layer made of a fluoropolymer having a low refractive index (JP-A-57-34526, JP-A-3-130103, JP-A-6-115023, and JP-A-8-15023).
Nos. 13702, 7-168004).
Layer Obtained by Sol-Gel Method (Japanese Unexamined Patent Publication (Kokai) No. 5-2088811)
, JP-A-6-299091 and JP-A-7-168003), or a layer containing fine particles (JP-B-60-59).
No. 250, JP-A-5-13021, JP-A-6-56478
No. 7, No. 7-92306, and No. 9-288201). In the layer containing fine particles, voids can be formed in the low refractive index layer as microvoids between the fine particles or in the fine particles. The layer containing the fine particles preferably has a porosity of 3 to 50% by volume, more preferably 5 to 35% by volume.

In order to prevent reflection in a wide wavelength range,
It is preferable that a layer having a high refractive index (medium / high refractive index layer) is laminated on the low refractive index layer. The refractive index of the high refractive index layer is 1.6
It is preferably 5 to 2.40, and more preferably 1.70 to 2.20. The refractive index of the middle refractive index layer is adjusted to be an intermediate value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably from 1.55 to 1.70. During·
The thickness of the high refractive index layer is preferably from 5 nm to 100 μm, more preferably from 10 nm to 10 μm, and most preferably from 30 nm to 1 μm. The haze of the middle / high refractive index layer is preferably 5% or more, more preferably 3% or less, and more preferably 1%.
It is most preferred that: The middle / high refractive index layer can be formed using a polymer binder having a relatively high refractive index. Examples of high refractive index polymers include:
Polystyrene, styrene copolymer, polycarbonate,
Included are melamine resins, phenolic resins, epoxy resins and polyurethanes obtained by reacting cyclic (alicyclic or aromatic) isocyanates with polyols. Other polymers having a cyclic (aromatic, heterocyclic, alicyclic) group and polymers having a halogen atom other than fluorine as a substituent also have a high refractive index. A polymer may be formed by a polymerization reaction of a monomer capable of radical curing by introducing a double bond.

In order to obtain a higher refractive index, inorganic fine particles may be dispersed in a polymer binder. The refractive index of the inorganic fine particles is preferably from 1.80 to 2.80. The inorganic fine particles are preferably formed from a metal oxide or sulfide. Examples of metal oxides or sulfides include titanium dioxide (eg, rutile, rutile / anatase mixed crystal, anatase, amorphous structure), tin oxide, indium oxide, zinc oxide, zirconium oxide, and zinc sulfide. Titanium oxide, tin oxide and indium oxide are particularly preferred. The inorganic fine particles contain oxides or sulfides of these metals as main components and may further contain other elements. The main component means a component having the largest content (% by weight) of the components constituting the particles. Examples of other elements include Ti, Zr, Sn, Sb, Cu, Fe, Mn,
Pb, Cd, As, Cr, Hg, Zn, Al, Mg, S
i, P and S are included. Inorganic materials that are film-forming and can be dispersed in solvents or are themselves liquid, such as alkoxides of various elements, salts of organic acids, coordination compounds (eg, chelate compounds) combined with coordination compounds, activity The middle / high refractive index layer can be formed using an inorganic polymer.

The anti-reflection layer can provide the surface with an anti-glare function (a function of scattering incident light on the surface to prevent a scene around the film from shifting to the film surface). For example, by forming fine irregularities on the surface of a transparent film, and forming an antireflection layer on the surface, or after forming the antireflection layer, by forming irregularities on the surface with an embossing roll, an anti-glare function is obtained. be able to.
An antireflection layer having an antiglare function generally has a haze of 3 to 30%.

(Electromagnetic Wave and Infrared Shielding Layer) In order to impart an electromagnetic wave shielding effect in the present invention, it is preferable to use a transparent conductive layer so as not to lower the transmittance of the front plate. Examples of the transparent conductive layer include metal-containing layers such as a noble metal thin film layer and a metal oxide thin film layer. Examples of the metal forming the noble metal thin film layer include gold, silver, palladium and alloys thereof, and preferably an alloy with silver and gold. In the case of an alloy, the silver content is preferably 60% or more. Examples of the metal oxide forming the metal oxide thin film layer include SnO ₂ and Zn.
O, ITO, In ₂ O _{3 and the} like can be mentioned. Further, it is preferable to laminate a transparent dielectric layer in order to protect the metal layer, prevent oxidative deterioration, and increase the transmittance of visible light. Examples of the transparent dielectric layer include thin films of oxides of divalent to tetravalent metals, zirconium oxide, titanium oxide, magnesium oxide, silicon oxide, aluminum oxide, and metal alkoxide compounds. When the transparent dielectric layer is provided on both the surface side and the substrate side of the metal layer, both may be the same substance. The thickness of the metal layer is 4 to 40 nm
Is preferably 5 to 35 nm, more preferably 6 to 30 n
m is most preferred. If the film thickness is less than 4 nm, the electromagnetic shielding effect is poor, and if it exceeds 40 nm, the transmittance of visible light decreases. The thickness of the transparent dielectric layer is desirably 20 to 300 nm. Within this range, visible light can be sufficiently transmitted. Preferably it is 40 to 100 nm. The method for forming the metal layer and the transparent dielectric layer is not particularly limited, and an arbitrary processing method can be selected. For example, any known technique such as a sputtering method, a vacuum evaporation method, an ion plating method, a plasma CVD method, or a PVD method can be used. To impart a near-infrared shielding effect, a method of mixing a near-infrared absorbing compound with a transparent plastic support can be used. For example, a resin composition containing a copper atom (JP-A-6-118228) and a resin composition containing a copper compound and a phosphorus compound (JP-A-62-128228)
No. 5190), a resin composition containing a copper compound and a thiourea derivative (JP-A-6-73197), and a resin composition containing a tungsten-based compound (US Pat.
29) can easily be manufactured. A method of forming a silver film on a transparent material is inexpensive and preferable as a method of providing an infrared shielding effect in addition to the electromagnetic shielding.

(Filter layer) The thickness of the filter layer is 1
It is preferably from 15 to 15 μm. The filter layer is
A wavelength range of 500 to 550 nm (green) and a wavelength of 56
It has an absorption maximum both in the range of 0 to 620 nm (between green and red). The transmittance at the absorption maximum in the wavelength range of 500 to 550 nm is preferably in the range of 50 to 85%. The absorption maximum in the wavelength range of 500 to 550 nm is set to adjust the emission intensity of the green phosphor having high visibility. It is preferable that the emission region of the green phosphor be cut smoothly. The half width at the absorption maximum in the wavelength range of 500 to 550 nm (the width of the wavelength region showing half the absorbance of the absorbance at the absorption maximum) is 30 to 300 nm.
Is preferably 40 to 300 nm, more preferably 50 to 150 nm, and most preferably 60 to 150 nm.

The transmittance at the absorption maximum in the wavelength range of 560 to 620 nm is preferably in the range of 5 to 50%. The absorption maximum in the wavelength range of 560 to 620 nm is set to selectively cut a sub-band that reduces the color purity of the red phosphor. In the PDP, unnecessary light emission near 595 nm emitted by excitation of neon gas is also cut. By separating the absorption maximum according to the present invention, light can be selectively cut without adversely affecting the color tone of the green phosphor. In order to further reduce the effect on the color tone of the green phosphor, it is preferable to sharpen the peak of the absorption spectrum. Specifically, the half width at the absorption maximum in the wavelength range of 560 to 620 nm is preferably 15 to 200 nm, more preferably 20 to 100 nm, and more preferably 22 to 80 nm.
Most preferably, it is nm.

In order to provide the above absorption spectrum,
A visible filter layer is formed using a dye (dye or pigment, preferably a dye). Wavelength 500-550n
As the dye having an absorption maximum in the range of m, a squarylium-based, azomethine-based, cyanine-based, oxonol-based, anthraquinone-based, azo- or benzylidene-based compound is preferably used. As azo dyes, GB539
No. 703, No. 5,756,691, US Pat. No. 2,956,879 and Hiroshi Horiguchi, "Review Synthetic Dyes", and many azo dyes described in Sankyo Publishing Co., Ltd. can be used. The general formula (a
The azo dyes represented by 6) are preferred. Examples of the dye having an absorption maximum in the wavelength range of 500 to 550 nm are shown below.

[0019]

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[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or a monovalent group, M represents a metal atom, and m ¹ , m ² and m ³ each independently represent 1 to
Represents an integer of 4. As a metal atom represented by M,
Transition metals are preferred, Fe, Co, Ni, Cu, Zn,
Cd and the like can be mentioned, and Cu is particularly preferred. As the dye having an absorption maximum in the wavelength range of 560 to 620 nm, cyanine, squarylium, azomethine, xanthene, oxonol or azo compounds are preferably used. 560 to 620 nm wavelength
Examples of dyes having an absorption maximum in the range of are shown below.

[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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A dye having an absorption maximum in both the wavelength range of 500 to 550 nm and the wavelength range of 560 to 620 nm can be used for the filter layer. For example, when the dye is in an aggregated state such as a fine particle dispersion, the wavelength generally shifts to the longer wavelength side, and the peak becomes sharp. For this reason, some dyes having an absorption maximum in the wavelength range of 500 to 550 nm have an aggregate having an absorption maximum in the range of 560 to 620 nm. When such a dye is used in a state of forming an aggregate partially, the wavelength is in the range of 500 to 550 nm and the wavelength is 560.
It is possible to obtain an absorption maximum in both the range from 620 nm to 620 nm. Examples of such dyes are shown below.

[0032]

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[0033]

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[0034]

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In the filter layer, two or more kinds of dyes as described above can be used in combination.

(Other Layers) The front plate of the present invention may be provided with a hard coat layer, a lubricating layer, an antistatic layer or an intermediate layer. The hard coat layer preferably contains a cross-linked polymer. The hard coat layer can be formed using an acrylic, urethane, or epoxy polymer, oligomer, or monomer (eg, an ultraviolet curable resin). The hard coat layer can also be formed from a silica-based material. A lubricating layer may be formed on the outermost surface of the front plate, for example, on the outermost surface of the antireflection film. The lubrication layer is
It has the function of imparting slipperiness to the antireflection film surface and improving scratch resistance. The lubricating layer is made of a polyorganosiloxane (eg,
Silicon oil), natural wax, petroleum wax, higher fatty acid metal salt, fluorine-based lubricant or a derivative thereof. The thickness of the lubricating layer is 2 to 20
It is preferably nm.

The anti-reflection layer (low-refractive index layer), visible filter layer, near-infrared or electromagnetic wave shielding filter layer, undercoat layer, hard coat layer, lubricating layer, and other layers are formed by a general coating method. Can be. Examples of the coating method include a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, and an extrusion coating method using a hopper (described in US Pat. No. 2,681,294). Is included. Two or more layers may be formed by simultaneous coating. For the simultaneous coating method, see US Pat.
No. 791, No. 2941898, No. 3508947,
No. 3,526,528, and in “Coating Engineering”, page 253, published by Asakura Shoten in 1973, by Yuji Harazaki. As the method for forming the antireflection layer in the present invention, a sputtering method, a vacuum evaporation method, an ion plating method, a plasma CVD method, or a PVD method may be appropriately selected in accordance with the improvement of the heat resistance of the transparent support. However, a coating method is more preferable.

(Use of Front Plate of the Present Invention) The front plate of the present invention is used for a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode ray tube display (CRT), and the like. Used for image display devices. Particularly when the front panel of the present invention is used as a front panel of a plasma display panel (PDP) and a cathode ray tube display (CRT), a remarkable effect is obtained. A plasma display panel (PDP) includes a gas, a glass substrate, an electrode, an electrode lead material, a thick-film printing material, a phosphor, and a front plate that protects a main body. There are two glass substrates, a front glass substrate and a rear glass substrate. An electrode and an insulating layer are formed on two glass substrates. A phosphor layer is further formed on the rear glass substrate. Two glass substrates are assembled, and gas is sealed between them. The front plate is located on the front surface of the main body so as to protect these plasma display main bodies. The front plate is made of a tempered glass or plastic plate (such as acrylic) having sufficient strength to protect the main body. The front plate of the present invention,
In addition to the usage of the existing front panel, it is also possible to use the front panel by directly attaching it to the plasma display body. Plasma display panels (PDPs) are already commercially available. Regarding the plasma display panel, see
JP-A-205643 and JP-A-9-306366.

[0039]

EXAMPLES Example 1 (Formation of Undercoat Layer) After a corona treatment was applied to both sides of a transparent polyethylene terephthalate film having a thickness of 100 μm,
A latex made of a styrene-butadiene copolymer having a refractive index of 1.55 and a glass transition temperature of 37 ° C. (manufactured by Zeon Corporation, LX407C5) was applied to both surfaces to form an undercoat layer. The film was dried so as to have a thickness of 300 nm on the surface on which the filter layer was to be provided and a thickness of 150 nm on the surface on which the low refractive index layer was to be provided.

(Formation of Second Undercoat Layer) A gelatin aqueous solution containing acetic acid and glutaraldehyde is applied on the undercoat layer on the surface on which the filter layer is to be provided to a thickness of 100 nm after drying, and the antireflection layer is formed. An acrylic latex (HA16, manufactured by Nippon Acrylic Co., Ltd.) having a refractive index of 1.50 and a glass transition temperature of 50 ° C. was applied on the undercoat layer on the surface to be provided so as to have a thickness of 20 nm after drying. An undercoat layer was formed.

(Formation of Low Refractive Index Layer as Antireflection Layer)
1.3 g of t-butanol was added to 2.50 g of a reactive fluoropolymer (JN-7219, manufactured by Nippon Synthetic Rubber Co., Ltd.)
The mixture was stirred at room temperature for 10 minutes and filtered with a 1 μm polypropylene filter. The obtained low-refractive-index layer coating solution is applied on one surface of a transparent support (a surface having a styrene-butadiene copolymer latex of 150 nm and an acrylic latex of 20 nm as an undercoat layer) using a bar coater to a dry film thickness of 96 nm. And dried and cured at 120 ° C. for 15 minutes to form a low refractive index layer.

(Formation of Filter Layer) In 180 g of a 10% by weight aqueous solution of gelatin, 0.05 g of dye (c1) and 0.15 g of dye (a6-1) were dissolved.
After stirring for minutes, the mixture was filtered with a 2 μm polypropylene filter. The obtained coating liquid for a filter layer was applied onto the second undercoat layer on the opposite side of the transparent support on which the low refractive index layer was applied, so that the dry film thickness was 3.5 μm.
After drying for 0 minute to form a filter layer, a support provided with an antireflection layer and a filter layer was prepared.

When the spectral transmittance of the support was examined,
It has absorption maximums at 535 nm and 595 nm, and the transmittance at the absorption maximum is 69% at 535 nm, and 595 n
m was 23%. The half width of the absorption maximum is
The absorption maximum at 535 nm was 63 nm, and the absorption maximum at 595 nm was 30 nm.

(Coating Electromagnetic Wave and Infrared Shielding Layer and Antireflection Layer on Transparent Glass Support) Silver was sputtered on the surface of a colorless transparent glass plate having a thickness of 3 mm, and the surface resistance was 2.
A film having a thickness of about 12 nm was applied so as to be 5 Ω / square cm. The optical film thickness (product of the refractive index and the film thickness) becomes 130 to 140 nm on the thus coated silver film in the order of MgF ₂ , then SiO ₂ , TiO ₂ , and MgF ₂ using a vacuum evaporation method. Was deposited as follows. When the reflectance of this antireflection film was measured, the surface reflectance was 0.6%. (Preparation of Front Plate) An acrylic pressure-sensitive adhesive was applied to a thickness of 30 μm on the filter layer surface of a polyethylene terephthalate film coated with a low refractive index layer and a filter layer, and the reflection of the glass plate on which the antireflection layer was deposited was performed. The front plate of the present invention was produced by attaching the protective layer to the surface opposite to the surface on which it was deposited.

Example 2 (Formation of Undercoat Layer) After a transparent polyethylene terephthalate film having a thickness of 100 μm was corona-treated on both sides,
A latex made of a styrene-butadiene copolymer having a refractive index of 1.55 and a glass transition temperature of 37 ° C (LX407C5, manufactured by Zeon Corporation) is provided on the surface on which the filter layer is provided.
Is applied so as to have a thickness of 300 nm, and the opposite surface on which the low refractive index layer is provided has a refractive index of 1.58 and a glass transition temperature −
A latex made of vinylidene chloride-acrylic acid-methyl acrylate copolymer at 10 ° C. was applied to a thickness of 145 nm.

(Formation of Second Undercoat Layer) A second undercoat layer was formed in the same manner as in Example 1.

(Formation of Low Refractive Index Layer as Antireflection Layer)
A low refractive index layer was formed in the same manner as in Example 1.

(Formation of Filter Layer) Dye (a6-1)
A filter layer was formed in the same manner as in Example 1 except that 0.15 g of the dye (a5) was used instead, and a support provided with an antireflection layer and a filter layer was produced.

When the spectral transmittance of the above support was examined,
It has absorption maximums at 534 nm and 594 nm, and the transmittance at the absorption maximum is such that the absorption maximum at 534 nm is 65%, 594 n
m was 21%. The half width of the absorption maximum is
The absorption maximum at 534 nm was 78 nm, and the absorption maximum at 594 nm was 28 nm.

(Preparation of Front Plate) Polyethylene coated with an antireflection layer and a filter layer in the same manner as in Example 1 on a glass transparent support provided with an electromagnetic wave and infrared shielding layer and an antireflection layer in the same manner as in Example 1. A terephthalate film was stuck to produce a front plate.

Example 3 (Formation of Undercoat Layer) An undercoat layer was formed in the same manner as in Example 1.

(Formation of Second Undercoat Layer) A second undercoat layer was formed in the same manner as in Example 1.

(Formation of Low Refractive Index Layer) A low refractive index layer was formed in the same manner as in Example 1.

(Formation of Filter Layer) Dye (a6-1)
A filter layer was formed in the same manner as in Example 1 except that 0.05 g of the dye (a1) was used instead, and a support provided with an antireflection layer and a filter layer was produced.

When the spectral transmittance of the support was examined,
It has absorption maximums at 533 nm and 594 nm, and the transmittance at the absorption maximum is 63% at 533 nm and 594 n.
m was 22%. The half width of the absorption maximum is
The absorption maximum at 533 nm was 63 nm, and the absorption maximum at 594 nm was 29 nm.

(Fabrication of front plate) Polyethylene having an antireflection layer and a filter layer coated thereon in the same manner as in Example 1 on a glass transparent support having an electromagnetic wave and infrared shielding layer and an antireflection layer coated thereon in the same manner as in Example 1. A terephthalate film was adhered to produce a front plate of the invention.

(Evaluation of Filter Function) Plasma Display Panel (PDS4202J-H, Fujitsu Limited)
Was removed, and the front plates prepared in Examples 1 to 3 were attached to the main body such that the filter layer faced the image display surface of the plasma display panel. The electromagnetic wave and near-infrared shielding layer are connected to the metal ground on the back of the plasma display panel, and the electromagnetic wave radiated from the plasma display panel conducts the voltage induced in the electromagnetic wave and near-infrared shielding layer to the ground to evaluate the function. Carried out. As evaluation items, measurement of electromagnetic wave and infrared shielding ability, contrast of a displayed image, and evaluation of color reproducibility by visual observation were performed. The electromagnetic wave shielding ability was 10 MHz to 200 MHz in any of Examples 1 to 3.
A minimum of 9 dB or more was obtained in the range of MHz, and the external leakage level of electromagnetic waves regulated by information processing devices and the like was achieved. In addition, the line spectrum shielding ability in the near infrared region,
It is about 8% at 800 nm, 3% or less at 850 nm,
Interference with the infrared remote control device installed in the surrounding area was prevented. Contrast and visual color reproducibility were significantly improved in all of Examples 1 to 3. The contrast is 10: 1 before replacing the front panel
However, in each of the examples, the ratio was 15: 1. Before replacing the front panel, it was confirmed that red with orange was improved to pure red, greenish blue to vivid blue, and yellowish white to pure white.

[Brief description of the drawings]

FIG. 1 is a conceptual cross-sectional view when a front plate of the present invention is used on a front surface of a main body A of a cathode ray tube display (CRT) or a plasma display panel (PDP). FIG. 1-1 is a conceptual diagram when the main body A and the front plate D are in close contact with each other, and FIG. A CRT or PDP B Support C Various filter layers and antireflection layers D Front plate

FIG. 2 is a schematic sectional view of a layer configuration of a front plate. Fig. 2-1
And FIG. 2-2 correspond to FIGS. 2-3 and 2-4 of FIG.
Is an example of a layer configuration corresponding to the arrangement of FIG. DESCRIPTION OF SYMBOLS 1 Anti-reflection layer 2 Electromagnetic wave and infrared shielding layer 3 Hard coat layer 4 Plastic transparent support 5 Filter layer 6 Glass transparent support

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02F 1/1335 G02F 1/1335 H01J 11/02 H01J 11/02 E 29/88 29/88 F term (reference) 2H048 AA09 AA12 AA16 AA18 AA25 2H091 FA01X FA37X FB02 FB12 LA03 LA08 5C032 AA07 EE01 EE03 EF01 EF02 5C040 MA02 MA08 5G435 AA16 BB02 BB05 BB06 BB12 DD12 FF14 GG12 GG31 GG33

Claims (8)

[Claims] 1. One or two transparent supports, a visible filter layer for absorbing visible light containing a dye and a polymer binder, a shielding filter layer having one or both of an infrared shielding function and an electromagnetic wave shielding function, A front plate for an image display device, comprising an antireflection layer having antireflection capability for visible light. 2. The visible filter layer has an absorption maximum having a transmittance of 50 to 85% in a wavelength range of 500 to 550 nm, and has a transmittance of 5 in a wavelength range of 560 to 620 nm.
The front plate for an image display device according to claim 1, wherein the front plate is a visible filter having an absorption maximum of about 60%. 3. The front plate for an image display device according to claim 1, wherein at least one of the transparent supports is made of glass, and the other is a transparent plastic plate. 4. The transparent support according to claim 1, wherein the transparent plastic plate is a transparent support having an undercoat layer containing a polymer having a glass transition temperature of 60 ° C. or lower and −20 ° C. or higher on at least one side. 4. The front plate for an image display device according to any one of items 3. 5. The front plate for an image display device according to claim 1, wherein said front plate has an anti-reflection layer on both sides thereof. 6. The front plate, comprising: a hard coat layer, an antifouling layer,
The front plate for an image display device according to claim 1, wherein the front plate has at least one of anti-glare layers. 7. The anti-reflection layer comprising:
The front plate for an image display device according to any one of claims 1 to 6, wherein the shielding plate layer, the glass plate, the visible filter layer, the transparent plastic plate, and the antireflection layer are laminated in this order. 8. The PDP front plate according to claim 1, wherein the front plate is used for a plasma display device.