JP2000193820A - Optical filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter having a color correction function appropriate to a display image. SOLUTION: In this optical filter with a transparent carrier laminated with a filter layer, the filter layer has absorption maxima in both wavelength ranges of 500-550 nm and 560-620 nm, and a transmittance range of 40-85% at the absorption maximum in the wavelength range of 500-550 nm and a transmittance range of 0.01-80% at the absorption maximum in the wavelength range of 560-620 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an optical filter having a transparent support and a filter layer. In particular,
The present invention relates to a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode ray tube display (CRT), a fluorescent display tube, and a surface of an image display device such as a field emission display. The present invention relates to an optical filter attached for improving color reproducibility.

[0002]

2. Description of the Related Art A liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode ray tube display (CRT),
2. Description of the Related Art An image display device such as a fluorescent display tube or a field emission display displays a color image by a combination of light of three primary colors of red, blue and green in principle. However, it is very difficult (practically impossible) to make light for display ideal three primary colors. For example, in a plasma display panel (PDP), it is known that light emitted from three primary color phosphors contains extra light (wavelength is in a range of 500 to 620 nm). Therefore, it has been proposed to perform color correction using a filter that absorbs light of a specific wavelength in order to correct the color balance of display colors. Japanese Patent Application Laid-Open No. 58-153904 discloses color correction using a filter.
No. 61-188501, JP-A-3-231988
No. 5,205,643, No. 9-145918, No. 9-306366, and No. 10-26704.

[0003] The image display device also needs to prevent reflection in addition to color correction. In other words, there is a problem that the contrast is reduced due to the background being reflected on the display. As means for solving this problem, various antireflection films have been proposed. The antireflection functional layers of the antireflection films proposed so far can be classified into vapor deposition layers and coating layers. Although the vapor deposition layer is superior from the viewpoint of optical functions, the coating layer has an advantage that it is easy to manufacture. The vapor deposition layer has been used for a long time as an antireflection film for lenses such as glasses and cameras. The deposition layer is formed by a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, or a PVD method. The coating layer is generally formed by applying fine particles and a binder. The coating layer is described in
Nos. 9-49501, 59-50401, 60-5
No. 9250 and JP-A-7-48527.

It is also conceivable to incorporate an antireflection function into the optical filter. The above-mentioned JP-A-61-188.
No. 501, JP-A-5-205643 and 9-1459
No. 18, No. 9-306366, and No. 10-26704 disclose optical filters having an antireflection function incorporated therein. JP-A-61-188501, JP-A-5-205643, JP-A-9-145918 and JP-A-9-145918
In the optical filter described in each publication of 306366,
A dye or a pigment is added to the transparent support so that the support functions as a filter. JP-A-10-26704
In the optical filter described in the publication, a hard coat layer (surface hardened layer) provided between the transparent support and the antireflection layer
And the hard coat layer functions as a filter.

[0005]

If the transparent support or the hard coat layer of the antireflection film is colored, the transparent support or the hard coat layer functions as a filter. However, the types of dyes and pigments that can be added to the transparent support and the hard coat layer are very limited. The transparent support is made from plastic or glass (usually plastic). 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. The hard coat layer is generally a layer containing a crosslinked polymer. The crosslinking reaction of the polymer is carried out after the application of the layer. Under the reaction conditions for crosslinking, there are many dyes and pigments that fade. 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, it is difficult to perform appropriate correction. The present inventor has tried to make a layer different from a transparent support or a hard coat layer, which has many restrictions on the types of dyes and pigments that can be used, function as a filter layer, and perform appropriate color correction for an image display device. An object of the present invention is to provide an optical filter having an appropriate color correction function for a display image.

[0006]

The object of the present invention has been attained by the following optical filters (1) to (9), an image display device (10) and a plasma display panel (11). (1) An optical filter in which a transparent support and a filter layer are laminated, wherein the filter layer has a wavelength of 500
550 nm and a wavelength range of 560 to 620 nm, and has an absorption maximum and a wavelength of 500 to 550 nm.
The transmittance at the absorption maximum in the range of nm is 40 to 85%, and the transmittance at the absorption maximum in the range of 560 to 620 nm is 0.01 to 80%. Optical filter. (2) The optical filter according to (1), wherein the transmittance at the absorption maximum in the wavelength range of 500 to 550 nm is larger than the transmittance at the absorption maximum in the wavelength range of 560 to 620 nm. (3) The optical filter according to (1), wherein the half-width at the absorption maximum in the wavelength range of 500 to 550 nm is larger than the half-width at the absorption maximum in the wavelength range of 560 to 620 nm. (4) The half width at the absorption maximum in the wavelength range of 500 to 550 nm is 30 to 300 nm, and the wavelength is 56
The optical filter according to (1), wherein the full width at half maximum at the absorption maximum in the range of 0 to 620 nm is 5 to 300 nm. (5) The optical filter according to (1), wherein the filter layer contains a dye and a binder polymer.

(6) The filter layer comprises a dye having an absorption maximum in the wavelength range of 500 to 550 nm and a dye having a wavelength of 56
A dye having an absorption maximum in a range of 0 to 620 nm. (7) A dye having an absorption maximum in a wavelength range of 500 to 550 nm is in a non-associated state, and has a wavelength of 560 to 620.
The optical filter according to (6), wherein the dye having an absorption maximum in a range of nm is in an associated state. (8) A low refractive index layer having a refractive index lower than that of the transparent support is further provided, and the filter layer, the transparent support, and the low refractive index layer are laminated in this order (1).
An optical filter according to item 1. (9) The low-refractive-index layer having a refractive index lower than that of the transparent support is provided, and the transparent support, the filter layer, and the low-refractive-index layer are laminated in this order. Optical filter. (10) An image display device in which the optical filter according to any one of (1) to (9) is mounted on a front surface of a display. (11) A plasma display panel in which the optical filter according to any one of (1) to (1) is mounted on a front surface of a display.

[0008]

By using a layer different from the transparent support or the hard coat layer as a filter layer, there is no restriction on the dye or pigment to be used, and an appropriate color correction function can be provided to the optical filter. became. The present inventor has also conducted research on an image display device (especially a PDP). As a result, extra light (wavelength in the range of 500 to 620 nm) included in light emission from the three primary color phosphors is more accurately determined at a plurality of wavelengths. Region (500-550 nm and 560
６620 nm). Therefore,
It is more appropriate to perform color correction in both wavelength ranges by dividing the wavelength range from 500 to 550 nm and the wavelength range from 560 to 620 nm, which is more appropriate for the image display device. Therefore, in the optical filter of the present invention,
The filter layer has an absorption maximum having a transmittance of 40 to 85% in a wavelength range of 500 to 550 nm, and a wavelength of 560.
An absorption maximum at which the transmittance becomes 0.01 to 80% is given in the range of from 620 nm to 620 nm. As a result, the optical filter of the present invention has an appropriate color correction function for an image display device.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The optical filter of the present invention has a transparent support and a filter layer. The optical filter may further have an arbitrary layer (eg, a low refractive index layer, a medium refractive index layer, a high refractive index layer, a hard coat layer, and an undercoat layer). When the optical filter has a layer other than the transparent support and the filter layer, there is a preferred layer configuration (layer arrangement order). FIG. 1 is a schematic cross-sectional view illustrating a layer configuration of the optical filter. The embodiment shown in (a1) of FIG. 1 has a layer structure in the order of the filter layer (2), the transparent support (1), and the low refractive index layer (3). The transparent support (1) and the low refractive index layer (3) have a refractive index satisfying the following relationship. Refractive index of low refractive index layer <refractive index of transparent support In the embodiment shown in FIG. 1 (a2), the filter layer (2), the transparent support (1),
It has a layer structure in the order of the hard coat layer (4) and the low refractive index layer (3). The embodiment shown in (a3) of FIG. 1 includes a filter layer (2), a transparent support (1), a hard coat layer (4),
It has a layer structure in the order of the high refractive index layer (5) and the low refractive index layer (3). The transparent support (1), the low refractive index layer (3) and the high refractive index layer (5) have a refractive index satisfying the following relationship. The refractive index of the low refractive index layer <the refractive index of the transparent support <the refractive index of the high refractive index layer In the embodiment shown in FIG. 1 (a4), the filter layer (2), the transparent support (1), the hard coat layer ( 4),
It has a layer structure of a middle refractive index layer (6), a high refractive index layer (5), and a low refractive index layer (3) in this order. The transparent support (1), the low-refractive-index layer (3), the high-refractive-index layer (5) and the medium-refractive-index layer (6) have a refractive index satisfying the following relationship. Refractive index of low refractive index layer <refractive index of transparent support <refractive index of medium refractive index layer <refractive index of high refractive index layer

The embodiment shown in FIG. 1 (b1) has a transparent support (1), a filter layer (2), and a low refractive index layer (3). The relationship between the refractive index of the transparent support (1) and the refractive index of the low refractive index layer (3) is the same as that of (a1). FIG.
In the embodiment shown in (b2), the transparent support (1), the filter layer (2), the hard coat layer (4), and the low refractive index layer (3)
In the following order. The embodiment shown in (b3) of FIG. 1 has a transparent support (1), a filter layer (2), a hard coat layer (4), a high refractive index layer (5), and a low refractive index layer (3). Having a configuration. The relationship between the refractive indices of the transparent support (1), the low refractive index layer (3) and the high refractive index layer (5) is (a)
Same as 3). The mode shown in (b4) of FIG. 1 includes a transparent support (1), a filter layer (2), a hard coat layer (4), a medium refractive index layer (6), a high refractive index layer (5), and a low refractive index. It has a layer configuration in the order of layer (3). The relationship between the refractive indices of the transparent support (1), the low refractive index layer (3), the high refractive index layer (5) and the middle refractive index layer (6) is the same as that of (a4).

(Transparent support) Examples of materials for forming the transparent support include cellulose esters (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose propionate, cellulose nitrate). , 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), polymethyl methacrylate, Syndiotactic polystyrene,
Includes polysulfone, polyethersulfone, polyetherketone, polyetherimide and polyoxyethylene. Cellulose triacetate, polycarbonate and polyethylene terephthalate are preferred.

The transmittance of the transparent support is preferably at least 80%, 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 absorber added is preferably 0.01 to 20% by weight of the transparent support, more preferably 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 , TiO ₂ , BaSO ₄ ,
CaCO ₃ , talc and kaolin are included. The transparent support may be subjected to a surface treatment. Examples of the 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. Glow discharge treatment, ultraviolet irradiation treatment, corona discharge treatment and flame treatment are preferred, and glow discharge treatment and ultraviolet treatment are more preferred. Further, an undercoat layer for strengthening the adhesion with the upper layer may be provided.

(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 in the range of 40 to 85%, 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 at the absorption maximum) is preferably 30 to 300 nm,
The thickness is more preferably 40 to 300 nm, further preferably 50 to 150 nm, and 60 to 1 nm.
Most preferably, it is 50 nm.

The transmittance at the absorption maximum in the wavelength range of 560 to 620 nm is in the range of 0.01 to 80%;
It is preferably in the range of 0.02 to 75%,
More preferably, it is in the range of 0.05 to 70%.
It is more preferably in the range of 2 to 65%, still more preferably in the range of 1 to 60%, and most preferably in the range of 5 to 50%. Wavelength is 56
The absorption maximum in the range of 0 to 620 nm is set in order to selectively cut the sub-bands that reduce 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 wavelength is 560 to 62
The half width at the absorption maximum in the range of 0 nm is from 5 to 300 n.
m, more preferably 10 to 200 nm, still more preferably 10 to 100 nm, still more preferably 10 to 80 nm, and most preferably 15 to 50 nm. The transmittance at the absorption maximum in the wavelength range of 500 to 550 nm is preferably larger than the transmittance at the absorption maximum in the wavelength range of 560 to 620 nm. Further, the half width at the absorption maximum in the wavelength range of 500 to 550 nm is preferably larger than the half width at the absorption maximum in the wavelength range of 560 to 620 nm.

Dye (dye or pigment, preferably dye)
Is used to impart the above absorption spectrum to the filter layer. As the dye having an absorption maximum in the wavelength range of 500 to 550 nm, a squarylium dye, an azomethine dye, a cyanine dye, an oxonol dye, an azo dye or a benzylidene dye is preferably used. Wavelength 500
Examples of dyes having an absorption maximum in the range of from 550 nm to 550 nm are shown below.

[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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[0022]

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As the dye having an absorption maximum in the wavelength range of 560 to 620 nm, a cyanine dye, a squarylium dye, an azomethine dye, a xanthene dye, an oxonol dye or an azo dye is preferably used. Wavelength 5
Examples of dyes having an absorption maximum in the range of 60 to 620 nm are shown below.

[0024]

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[0025]

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In the filter layer, two or more kinds of dyes as described above can be used in combination. Further, the wavelength is in the range of 500 to 550 nm and the wavelength is 560 to 6 nm.
Dyes having absorption maxima in both the 20 nm ranges can be used in 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 that 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 partially forming an aggregate, a wavelength of 500 to 5
50 nm range (non-association state) and wavelength 560-62
Absorption maxima can be obtained in both the 0 nm range (association state). Examples of dyes having an absorption maximum in both the wavelength range of 500 to 550 nm and the wavelength range of 560 to 620 nm are shown below.

[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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Further, a non-associative dye is used as a dye having an absorption maximum in a wavelength range of 500 to 550 nm, and another dye in an associated state is used as a dye having an absorption maximum in a wavelength range of 560 to 620 nm. You may. The non-associative dye having an absorption maximum in the wavelength range of 500 to 550 nm is preferably an oxonol dye, a merocyanine dye, an arylidene dye, an azo dye, an azomethine dye or an anthraquinone dye. As the associated dye having an absorption maximum in the wavelength range of 560 to 620 nm, a cyanine dye is particularly preferably used. In addition,
In this specification, the absorption maximum of the dye in solution is 50 n
The state where the absorption maximum moves to the longer wavelength side by m or more is called an association state. Then, a state in which the movement of the absorption maximum is less than 50 nm is referred to as a non-association state. In the dye in the association state,
The movement of the absorption maximum is preferably 60 nm or more,
It is more preferably at least 70 nm, most preferably at least 80 nm. For non-associative dyes,
The movement of the absorption maximum is preferably less than 40 nm,
More preferably, it is less than 30 nm, most preferably less than 20 nm.

The filter layer preferably further contains a polymer binder. As the polymer binder, natural polymers (eg, gelatin, cellulose derivatives,
Alginic acid) or a synthetic polymer (eg, polymethyl methacrylate, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl chloride, styrene-butadiene copolymer, polystyrene, polycarbonate, water-soluble polyamide) can be used. Particularly preferred are hydrophilic polymers (the above-mentioned natural polymers, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl alcohol, and water-soluble polyamide).

An anti-fading agent may be added to the filter layer. Examples of anti-fading agents that function as dye stabilizers include hydroquinone derivatives (US Pat. No. 3,935,016).
Nos. 3,982,944), hydroquinone diether derivatives (described in U.S. Pat. No. 4,254,216 and JP-A-55-21004), phenol derivatives (described in JP-A-54-145530),
Derivatives of spiroindane or methylenedioxybenzene (UK Patent Publications Nos. 2077455 and 2062888)
And the derivatives of chroman, spirochroman or coumaran (U.S. Pat. Nos. 3,432,300 and 3,573,050).
Nos. 3574627 and 3764337 and JP-A Nos. 52-152225 and 53-20327.
Nos. 53-17729 and 61-90156), hydroquinone monoether or paraaminophenol derivatives (UK Patent 1347556,
Nos. 2066975 and JP-B-54-12
337, JP-A-55-6321) and bisphenol derivatives (described in US Pat. No. 3,700,455 and JP-B-48-31625).

In order to improve the stability of the dye to light or heat, a metal complex (described in US Pat. No. 4,245,018 and JP-A-60-97353) may be used as an anti-fading agent. In order to further improve the light fastness of the dye, a singlet oxygen quencher may be used as an anti-fading agent. Examples of the singlet oxygen quencher include a nitroso compound (described in JP-A-2-300288), a diimmonium compound (described in US Pat. No. 4,656,612), a nickel complex (described in JP-A-4-146189), and antioxidant. Agent (European Patent Publication 820057A1)
Description).

(Undercoat layer) It is preferable to provide an undercoat layer between the transparent support and the filter layer. The undercoat layer is formed as a layer containing a polymer having a glass transition temperature of −60 to 60 ° C., a layer having a rough surface on the filter layer side, or a layer containing a polymer having an affinity for the polymer of the filter layer. An undercoat layer is provided on the surface of the transparent support on which the filter layer is not provided to improve the adhesion between the transparent support and a layer provided thereon (for example, an antireflection layer or a hard coat layer). Is also good. The undercoat layer may be provided to improve the affinity between the optical filter and an adhesive for bonding the optical filter and the image forming apparatus. The thickness of the undercoat layer is preferably 2 nm to 20 μm, more preferably 5 nm to 5 μm, and 20 nm
To 2 μm, more preferably 50 nm to 1 μm, and most preferably 80 nm to 300 nm.

An undercoat layer containing a polymer having a glass transition temperature of -60 to 60 ° C. adheres the transparent support and the filter layer due to the tackiness of the polymer. Glass transition temperature is -6
Polymers at 0 to 60 ° C. include vinyl chloride, vinylidene chloride, vinyl acetate, butadiene, neoprene, styrene,
It can be obtained by polymerization or copolymerization of chloroprene, acrylate, methacrylate, acrylonitrile or methyl vinyl ether. The glass transition temperature is preferably 50 ° C. or lower, more preferably 40 ° C. or lower, further preferably 30 ° C. or lower, further preferably 25 ° C. or lower, further preferably 20 ° C. or lower. Is most preferred. The elastic modulus of the undercoat layer at 25 ° C. is preferably from 1 to 1000 MPa, more preferably from 5 to 800 MPa, and most preferably from 10 to 500 MPa. 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. The average particle size of the latex is preferably from 0.02 to 3 μm, more preferably from 0.05 to 1 μm. Examples of polymers having an affinity for the binder polymer of the filter layer include acrylic resins, cellulose derivatives, gelatin, casein, starch, polyvinyl alcohol, soluble nylon, and polymer latex. Two or more undercoat layers may be provided. 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.

(Anti-Reflection Layer) An anti-reflection layer may be provided on the optical filter to give the optical filter an anti-reflection function. As the antireflection layer, a low refractive index layer is essential. The refractive index of the low refractive index layer is lower than the refractive index of the transparent support. The refractive index of the low refractive index layer is 1.20 to 1.5
5, and more preferably 1.30 to 1.50. The thickness of the low refractive index layer is preferably 50 to 400 nm, and 50 to 200 nm.
Is more preferable. The low refractive index layer is a layer made of a fluorine-containing polymer having a low refractive index (JP-A-57-345).
No. 26, JP-A-3-130103, and JP-A-6-11502
3, No. 8-313702, and No. 7-168004), and a layer obtained by a sol-gel method (Japanese Unexamined Patent Application Publication No.
Nos. -2088811, 6-299091 and 7-16
No. 8003) or a layer containing fine particles (JP-B-60-59250, JP-A-5-13021, JP-A-6-56478, JP-A-7-92306, and 9-288).
No. 201). 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 to laminate a layer having a high refractive index (middle / high refractive index layer) in addition to the low refractive index layer. The high refractive index layer preferably has a refractive index of 1.65 to 2.40.
More preferably, it is 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 1.50 to 1.90, more preferably from 1.55 to 1.70. The thickness of the middle / 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 less, more preferably 3% or less, and most preferably 1% or less. 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 copolymers, polycarbonates, 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) among 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%.

(Other Layers) The optical filter may be provided with a hard coat layer, a lubricating layer, an antistatic layer or an intermediate layer. The hard coat layer has an altitude higher than the hardness of the transparent support. The hard coat layer preferably contains a cross-linked polymer. The hard coat layer is made of acrylic, urethane, or epoxy polymer,
It can be formed using an oligomer or a 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 surface of the antireflection layer (low refractive index layer). The lubricating layer has a function of imparting lubricity to the surface of the low refractive index layer and improving scratch resistance. The lubricating layer can be formed using polyorganosiloxane (eg, silicone oil), natural wax, petroleum wax, higher fatty acid metal salt, fluorine-based lubricant or a derivative thereof. Lubricating layer thickness is 2-20n
m is preferable.

The filter layer, undercoat layer, antireflection layer (medium-refractive-index layer, high-refractive-index layer, low-refractive-index 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. The simultaneous coating method is described in U.S. Pat.
No. 41898, No. 3508947, No. 3526528
Issue specifications and Yuji Harazaki, "Coating Engineering" 2
It is described on page 53 (published by Asakura Shoten in 1973).

(Use of Optical Filter) The optical filter is applied to an image display device such as a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display (CRT). . When the low refractive index layer is provided, the low refractive index layer is disposed such that the surface on which the low refractive index layer is not provided faces the image display surface of the image display device. When the optical filter of the present invention is used as a filter of a plasma display panel (PDP), a particularly 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, and a phosphor. 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. Assemble two glass substrates,
Meanwhile, gas is sealed. Plasma display panels (PDPs) are already commercially available. The plasma display panel is described in JP-A-5-205643 and JP-A-9-306366. In an image display device such as a plasma display panel, an optical filter is disposed in front of a display. An optical filter can be attached directly to the surface of the display. When a front panel is provided in front of the display, an optical filter can be attached to the front side (outside) or the rear side (display side) of the front panel.

[0047]

[Example 1] (Formation of undercoat layer) After 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 was applied on one side to a thickness of 130 nm to form an undercoat layer.

(Formation of Second Undercoat Layer) On the undercoat layer,
A gelatin aqueous solution containing acetic acid and glutaraldehyde was applied to a thickness of 50 nm to form a second undercoat layer.

(Formation of Low Refractive Index Layer) Reactive Fluoropolymer (JN-7219, manufactured by Nippon Synthetic Rubber Co., Ltd.) 2.50
1.3 g of t-butanol was added to the resulting mixture, and the mixture was stirred at room temperature for 10 minutes and filtered with a 1 μm polypropylene filter.
The obtained coating liquid for a low refractive index layer was coated on a surface opposite to the undercoat surface of the transparent support with a dry film thickness of 1 using a bar coater.
It was applied to a thickness of 10 nm, dried at 120 ° C. for 30 minutes and cured 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 (b4) and 0.05 g of dye (a1) were dissolved and stirred at 40 ° C. for 30 minutes. And filtered. The obtained coating solution for a filter layer was applied onto the second undercoat layer so that the dry film thickness became 3.5 μm.
After drying at 20 ° C. for 10 minutes to form a filter layer, an optical filter was produced.

When the spectral transmittance of the optical filter was examined, it had absorption maximums at 530 nm and 594 nm, and the transmittance at the absorption maximum was 70% at 530 nm and 59%.
The absorption maximum at 4 nm was 30%. As for the half width of the absorption maximum, the absorption maximum at 530 nm was 110 nm, and the absorption maximum at 594 nm was 35 nm.

Example 2 (Formation of Undercoat Layer) On one side of a transparent cellulose triacetate film having a thickness of 80 μm, gelatin dispersed in methanol and acetone was applied to a thickness of 200 nm, and dried to form an undercoat layer. Formed.

(Formation of Hard Coat Layer) 25 parts by weight of dipentaerythritol hexaacrylate (DPHA,
Nippon Kayaku Co., Ltd.), 25 parts by weight of a urethane acrylate oligomer (UV-6300B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 2 parts by weight of a photopolymerization initiator (IRGACURE-
907, Ciba-Geigy) and 0.5 parts by weight of a sensitizer (Kayacure-DETX, manufactured by Nippon Kayaku Co., Ltd.)
It was dissolved in 0 parts by weight of methyl ethyl ketone. The obtained coating solution was applied to the surface of the transparent support opposite to the undercoating surface using a bar coater, dried, and irradiated with ultraviolet rays to form a hard coat layer (layer thickness: 6 μm).

(Formation of Low Refractive Index Layer) On the hard coat layer, a coating liquid for a low refractive index layer containing the reactive fluoropolymer used in Example 1 was applied in the same manner as in Example 1 to obtain a low refractive index layer. A rate layer was formed.

(Formation of Filter Layer) 0.05 g of the dye (c1) was dissolved in 180 g of a 10% by weight aqueous solution of gelatin, stirred at 40 ° C. for 30 minutes, and filtered with a 2 μm polypropylene filter. The obtained coating solution for a filter layer was applied onto the undercoat layer so that the dry film thickness became 3.5 μm, and dried at 120 ° C. for 10 minutes to form a filter layer, thereby producing an optical filter. FIG. 2 shows the spectral transmittance of the produced optical filter. As shown in FIG. 2, it has absorption maxima at 527 nm and 596 nm,
The transmittance at the absorption maximum is 80 when the absorption maximum at 527 nm is 80.
%, The absorption maximum at 596 nm was 25%. The half maximum width of the absorption maximum is such that the absorption maximum at 527 nm is 90 nm and 596.
The absorption maximum in nm was 30 nm.

[Example 3] (Formation of undercoat layer) In the same manner as in Example 1, an undercoat layer (a) and a second undercoat layer (a) were formed on one surface of the transparent support. A latex made of vinylidene chloride-acrylic acid-methyl acrylate copolymer was applied to a thickness of 120 nm on the surface of the transparent support on which the undercoat layer was not provided, to form an undercoat layer (b).

(Formation of Second Undercoat Layer) On the undercoat layer (b), an acrylic latex (HA16, manufactured by Nippon Acrylic Co., Ltd.) was applied to a thickness of 50 nm to form a second undercoat layer (b). Was formed.

(Formation of Filter Layer) A filter layer was formed on the second undercoat layer (b) in the same manner as in Example 1.

(Formation of Hard Coat Layer and Low Refractive Index Layer) On the filter layer, a hard coat layer and a low refractive index layer were formed in the same manner as in Example 2, to produce an optical filter. When the spectral transmittance of the manufactured optical filter was examined, it had absorption maximums at 530 nm and 594 nm, and the transmittance at the absorption maximum was 70% at 530 nm.
The absorption maximum at 594 nm was 30%. The half width of the absorption maximum is such that the absorption maximum at 530 nm is 110 nm and 594 n.
m had an absorption maximum of 35 nm.

Example 3 Dyes (b4) and (a1)
In place of, 0.08 g of the dye (c13) and (a6)
An optical filter was produced in the same manner as in Example 1 except that 0.10 g was used. When the spectral transmittance of the manufactured optical filter was examined, it had an absorption maximum at 532 nm and 593 nm, and the transmittance at the absorption maximum was 72% at 532 nm and 4% at 593 nm. The half width of the absorption maximum is 95 at the absorption maximum at 532 nm.
The absorption maximum at nm and 593 nm was 33 nm.

Comparative Example 1 (Formation of Filter Layer) 10% by weight aqueous solution of gelatin 1
Dissolve 0.05 g of dye (b3) in 80 g,
, And filtered through a 2 μm polypropylene filter. An optical filter was prepared in the same manner as in Example 1, except that the obtained coating solution for a filter layer was used. When the spectral transmittance of the optical filter was examined,
It had an absorption maximum only at 96 nm, the transmittance at the absorption maximum was 25%, and the half width of the absorption maximum was 35 nm.

Comparative Example 2 (Formation of Filter Layer) 10% by weight aqueous solution of gelatin 1
Dissolve 0.05 g of dye (a4) in 80 g,
, And filtered through a 2 μm polypropylene filter. An optical filter was prepared in the same manner as in Example 1, except that the obtained coating solution for a filter layer was used. When the spectral transmittance of the optical filter was examined,
It had an absorption maximum only at 27 nm, the transmittance at the absorption maximum was 80%, and the half width of the absorption maximum was 90 nm.

(Evaluation of Filter Function) Plasma Display Panel (PDS4202J-H, Fujitsu Limited)
Film) on the outermost surface of the front plate of the optical filter (the surface on the side where the low refractive index layer is not provided) produced in Examples 1 to 4 and Comparative Examples 1 and 2 instead of an adhesive. Pasted. The displayed images were evaluated for contrast and visually evaluated for white light and red light. The results are shown in Table 1.

[0064]

[Table 1] Table 1 光学 Optical filter Contrast White light Red light ──────────────────────────────────── Example 1 15: 1 White (improved) Red (improved) Example 2 15: 1 White (Improved) Red (Improved) Example 3 15: 1 White (Improved) Red (Improved) Example 4 15: 1 White (Improved) Red (Improved) Comparative Example 1 14: 1 Green Tinged white red (improved) Comparative Example 2 14: 1 white (improved) orange tinged red without filter 10: 1 green tinged white orange tinged red ───────────────────────

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a layer configuration of an optical filter.

FIG. 2 is a graph showing the spectral transmittance of the optical filter manufactured in Example 2. DESCRIPTION OF SYMBOLS 1 Transparent support 2 Filter layer 3 Low refractive index layer 4 Hard coat layer 5 High refractive index layer 6 Medium refractive index layer

Claims (11)

[Claims] 1. An optical filter comprising a transparent support and a filter layer laminated on each other, wherein the filter layer has a wavelength in the range of 500 to 550 nm and a wavelength in the range of 560 to 62.
It has an absorption maximum in both the range of 0 nm and a transmittance of 40 to 8 at the absorption maximum in the wavelength range of 500 to 550 nm.
An optical filter having a transmittance of 5% and a transmittance of 0.01 to 80% at an absorption maximum in a wavelength range of 560 to 620 nm. 2. The optical filter according to claim 1, wherein the transmittance at the absorption maximum in the wavelength range of 500 to 550 nm is larger than the transmittance at the absorption maximum in the wavelength range of 560 to 620 nm. 3. The optical filter according to claim 1, wherein the half width at the absorption maximum in the wavelength range of 500 to 550 nm is larger than the half width at the absorption maximum in the wavelength range of 560 to 620 nm. 4. A half-width at an absorption maximum in a wavelength range of 500 to 550 nm is 30 to 300 nm, and a half-width at an absorption maximum in a wavelength range of 560 to 620 nm is 5 to 300 nm. An optical filter according to item 1. 5. The optical filter according to claim 1, wherein the filter layer contains a dye and a binder polymer. 6. The filter layer having a wavelength of 500 to 55.
6. The optical filter according to claim 5, comprising a dye having an absorption maximum in a range of 0 nm and a dye having an absorption maximum in a range of 560 to 620 nm. 7. The optical device according to claim 6, wherein the dye having an absorption maximum in a wavelength range of 500 to 550 nm is in a non-associative state, and the dye having an absorption maximum in a wavelength range of 560 to 620 nm is in an associated state. filter. 8. The method according to claim 1, further comprising a low refractive index layer having a refractive index lower than that of the transparent support, wherein the filter layer, the transparent support, and the low refractive index layer are laminated in this order. An optical filter according to item 1. 9. The method according to claim 1, wherein a low refractive index layer having a refractive index lower than that of the transparent support is provided, and the transparent support, the filter layer, and the low refractive index layer are laminated in this order. The optical filter as described. 10. An image display device comprising the optical filter according to claim 1 arranged on a front surface of a display. 11. A plasma display panel in which the optical filter according to claim 1 is arranged on a front surface of a display.